Lulzbot Mini / Prusa Mini Hybrid: Update #2: Marlin Updates, Novel Bed Mount, Octoprint, PrusaSlicer and Ultimaker Cura.

So it has been awhile since I worked on this project, but I am happy to report that after a few weeks of minor frustration with marlin hiccups I have now started to make big progress again.

First test prints with Lulzbot mini / Prusa Mini Hybrid Mod. Print is obviously not centered on the new bed but my z-axis did not crash!

My top objectives are:

1. To get a Lulzbot Mini 1 modded (with minimal effort) to have a Prusa Mini removable bed plate system. Done!

2. To continue to use the original stock Rambo Mini 1.1b electronics board, but with a new up-to-date (custom) marlin firmware. Done!

3. To be able to print like I did before with everything centered and adjusted to the correct height for printing on the new removable print bed. And to be able to print with the old Lulzbot Cura 21.08 or the newer PrusaSlicer. Done-ish, but needs tweaking!

Other future modifications may be: An upgrade to a newer Rambo Einsy with trinamic stepper drivers for ultra quiet use. Possible z-axis modifications to be more like a Lulzbot Mini 2. A new extruder design with possible automatic bed leveling sensor pinda probe. Add an LCD screen!

I was testing with the marlin 2.0 bugfix branch

The first major hurdle lately has been trying to update to Marlin 1.9 or Marlin 2.0 with the configuration settings to work correctly with the Lulzbot Mini. I got pretty far along when i decided i wanted to center my new prusa mini bed plate when a print begins.

I ran into a weird Marlin bug where the manual_y_home_pos setting would invert the y-axis stepper motor and crash the machine! I tried reporting the bug to the marlin code people, but no one would help. They just kept asking the same annoying question over and over whether I was testing with the bug fix branch, which i replied multiple times that i was.

The “fix” for this came from a helpful tip from my friend who suggested i use the “Drunken Octopus” Marlin fork which was originally being maintained by lulzbot before the awful situation where they nearly went bankrupt, fired over 100+ employees illegally, and eventually got bought out and moved to North Dakota. It worked, so I’m thinking it must come down to some overlooked configuration setting I must have missed??

The Drunken Octopus fork is now maintained for lulzbot-type machines by that same former employee and is now also used for the new SynDaver Axi Desktop Printer which is a 70-80% clone of the Lulzbot Taz 6 / Pro series. The SynDaver Axi printer is not entirely open source being a hybrid of open source and proprietary, which is an interesting mix, but I don’t necessarily have a problem with that as long as the original source is available (which is).

In an ideal world I do think some licences like the new CERN-OHL-S Licence are what open source hardware and software should aspire to be. Basically the idea that if you use open source that the whole product from then on and forever will be open source. That would mean no mixing of open source and proprietary. But we do not live in an ideal world (yet). I personally think creative commons licences with non-commercial, no-derivatives, and other restrictive licences are insulting and are NOT true open source. I personally do not honor them because of their inherit hypocrisy. If you want to share your work with the world then do so in it’s entirety or don’t do so at all. I’m not the only one with this opinion, in fact the OSHWA says so as well.

Why aren’t non-commercial restrictions compatible with open source hardware?

There are a few reasons. If you place a non-commercial restriction on your hardware design, other people don’t have the same freedom to use the design in the ways that you can. That means, for example, that if you and someone else both release designs with non-commercial licenses, neither of you can make and sell hardware that builds on both of your designs. Rather than contributing to a commons of hardware designs for everyone to build on, you’re limiting others to a very narrow range of possible uses for your design. In particular, because making hardware invariably involves money, it’s very difficult to make use of a hardware design without involving some commercial activity. For example, say a group of friends wanted to get together and order ten copies of a hardware design – something that’s often much cheaper than each person ordering their own copy. If one person places the order and the others pay him back for their share, they’d probably be violating a non-commercial restriction. Or say someone wants to charge people to take a workshop in which they make and keep a copy of your hardware design – that’s also commercial activity. In general, there are just very few ways for someone to use a hardware design without involving some sort of commercial activity.

Good for SynDaver for swooping in and hiring a bunch of Lulzbot’s former abandoned employees, a hilarious move I must say. You can see why I no longer am supportive of Lulzbot as a company, and Jeff Moe in particular. Funny how Lulzbot created their own competition. Up to this point it was perfectly conceivable that a Chinese (or any) company could clone the Lulzbot series completely like they have the Prusa printers, but up to this point no one ever had.

Anyway, back to the modification project. Things are going well. I have successfully test printed a few times. At first the prints were not centered on the bed, but I finally figured that out. I now am testing manual mesh bed leveling code in the marlin firmware and despite not having an automatic bed leveling probe it seems I can get this to work without one. I have not yet enabled memory saving so as of now i need to level the bed every time I use it, and this slows the whole process down a lot. I probably will enable that next so i can use octoprint again and just click “send print to printer”.

Eventually I want to replace the extruder assembly with one that has a pinda probe. I’m actually thinking I may want to use a Prusa MK3S printhead to keep things compatible with my other build. Not sure whether i will need to make other mods to accommodate that or not. I will at the very least need a cable adapter. If / when I do that I will most likely swap out the Rambo Mini for the Rambo Einsy (that i bought from Ultimaker) for the trinamic drivers and LCD support.

I came up with what I think is a pretty clever mounting system that still is fast, easy, and a complete drop-in replacement with no major modifications to either the prusa hardware or the lulzbot hardware. The only modifications needed were a small adapter for the heatbed cable and thermistor wires, and some countersunk holes on the bottom side of the prusa mini bed plate. The rest were 4 3D-printed ninjaflex corner mounts that hold things together quite well. I have posted the files on Thingiverse & soon to YouMagine.

I am happy with how this mod has been turning out. I have tried to do it step by step with as few mini mods as possible so that it could perhaps be done by anyone, with any version of a Lulzbot Mini (1 or 2). I have tried not to stack the mods so that if one person wanted to repeat my process and only do just the bed replacement on a really old Lulzbot Mini 1 without changing the electronics or the extruder print head then that would work. On the other hand if someone wanted to do this on a Lulzbot Mini 2 or in combinations with other mods, those could probably work fine too. The firmware does need to be replaced regardless though as the bed height is higher than the old one and no bed leveling probe is currently installed so major z-axis crashing would occur.

I at least have a fairly up to date version of Marlin working decently well now. It uses the Drunken Octopus fork and is fairly up to date with Marlin 2.0 and other upstream changes. So in many ways this firmware is an upgrade to what was on my mini before I started and can only improve. I want to double check motor settings for speeds and feedrates to make sure I have things optimized as best I can. But otherwise it seems to be working well with a properly tuned slicer.

A bad print before manual mesh bed leveling was attempted.

I have also officially abandoned the Lulzbot Cura 21.08 slicer. I was using the old Lulzbot Cura 21.08 instead of the newer Lulzbot Cura 2 because the older software just ran so quick compared to the new one and frankly I thought the new one sucked and looked like crap. I still do if i’m honest. But since I no longer have a stock Lulzbot machine anyway I figured I would give the newest version of the Ultimaker Cura a try. I was pleasantly surprised!

A better print after manual mesh bed leveling. I accidentally bumped the raspberry pi running octoprint, so that is why the print is only half finished.

Not only is the Ultimaker Cura more up to date and more polished than the Lulzbot fork, it comes in a better Linux package than the Lulzbot version that is not up to date with needed dependencies on my newer PopOS 20.04 laptop. So I literally could not even install the Lulzbot skinned version of Cura 2 on my Linux machine. Once I set up a custom printer in Ultimaker Cura I was pleased to find it worked great! It even made the motors twice as quiet! I tinkered around with trying to use PrusaSlicer to slice and control the lulzbot mini, but i have not figured out the best settings for the motors quite yet. I got it to work once, then it reverted to it’s default motor settings and sounded terrible. Since Ultimaker’s Cura worked flawlessly with no motor adjustments and the motors were so quiet compared to the old Lulzbot Cura 21.08 and PrusaSlicer (for now), I will be using Ultimaker’s Cura until I am ready to tinker with PrusaSlicer again.

Lulzbot-Prusa Mini Hybrid: First Test Print

Today i finally had some time to try and get my Lulzbot-Mini Prusa Hybrid bed working. I made some adapter cables to connect the Prusa Mini heat bed to my Lulzbot Mini electronics. They work great. The bed heats up very fast, probably better than the original Lulzbot heat mat. And it has a really awesome red indicator LED to let you know when it is heating. Really Cool!

Making good progress on it. Decided that with removing the bed levelling washers i needed to flash custom marlin firmware. I grabbed Marlin 2.0 and got nearly everything configured and even got a test print (although it needs some tuning). The problems arose when i tried to follow this guide to center the print on the new print bed.

When i went to uncomment the //#define MANUAL_X_HOME_POS & the //#define MANUAL_Y_HOME_POS i ran into really weird problems. I was able to get the x-axis to center although instead of being a negative value it was positive. But when i went to put in the values for Y i got some weird grinding sounds as if the stepper motor was running the wrong way. I tried switching the y value to the opposite since the y axis is flipped, but either way it does not work. Additionally when inputting a G00 X90 command sometimes the Y-Axis will move too! This should not be happening! And only seems to cause issues when the #define MANUAL_Y_HOME_POS is uncommented. I’m wondering if i encountered a weird bug in Marlin 2.0. Some have suggested that Marlin is more stable.

Anyway, any suggestions? Comments on my project? This is the first time i have dug into marlin on my own.

At the moment i am choosing to get it working with minimal changes to the electronics including using the original Rambo Mini 1.1b. Eventually i will change it to the the new Rambo Einsy board with a pinda probe an LCD screen. But i want it to work as is to start.


LulzbotMini-PrusaMini Hybrid: Update #1

Lulzbot Mini – Prusa Mini Hybrid 3D Printer Mod

The flexible metal build plate mod for my old scratch-built lulzbot mini 1 is well underway. I had to order some countersunk metric screws and binding posts from Amazon. I also had to countersink a few holes on the bottom for this to fit together flush like i want it to. Other than that though there has not been much modding at all really. I do still have to mesh the wires together or replace some connectors, but i expect that to be very minor.

Prusa Mini heat bed plate mounted on a Lulzbot Mini

The new ninjaflex mounting pads (that i printed on my new Prusa Mini) seem to be nearly perfect. The Prusa Mini bed plate sits very well and is surprisingly a very clean and nearly drop in replacement for the old crappy glass bed that Lulzbot uses. I think i may need to drill a few new holes in the prusa base plate on the bottom to secure this down solid, but as of now this thing probably could be wired up and tested. And to be honest i probably will.

Modified Prusa Mini bed plate to have countersunk holes
Prusa Mini Bed Plate for Lulzbot Mini Modification

I’m thinking that the major change would be the z-offset height. If the z-offset height were adjusted properly and the lulzbot nozzle cleaning routine deleted i would foresee no major problems. Sure, bed levelling via washers will no longer be automatic, but who really cares that much. I’ve seen the old Lulzbot Taz 5 machines and they have no automatic bed levelling and they seem to work fine. This would be the fastest and easiest way to implement this mod. No changes in firmware, electronics, or extruder mods other than the bed itself.

Lulzbot Mini with metal bed plate

I do however have some more plans for my Lulzbot 1 machine. The first is that i do plan on making an extruder mod that will implement the bed levelling sensor that Prusa uses on it’s machines. This will need to be done in concert with replacing the whole board with a new Einsy board. In my case ii have chosen to go with the Prusa version, the Einsy Rambo 1.2b from Ultimaker with the Prusa Bootloader, rather than the Einsy Retro that the Lulzbot Mini 2 uses.

Lulzbot Mini with metal bed plate

I decided on this route for several reasons. First I’m planning on making my own Prusa i3 MK3S clone from scratch and I’d like these two printers to have compatible electronics hardware and firmware. The second is that the Einsy Retro does not have the correct connector for the metal bed plate leveling sensor. I could probably hack together an adapter cable if i had to, but i don’t want to. Simplicity and swapability is what i want.

Previewing a possible LCD Mod for the Lulzbot Mini

Another plan i have for this machine is to finally give this machine an LCD screen. Something the original Lulzbot Mini was not capable with the mini rambo board that my machine used without some extensive hacking. I have again decided to use the Prusa i3 MK3S LCD screen from Printed Solid rather than use the same size that the Lulzbot Mini 2 is using.

Previewing a possible LCD Mod for the Lulzbot Mini

Why? Because of swapability and firmware sameness, but also because the Lulzbot Mini 2 LCD screen is $125!! No way is that LCD screen and 3D printed plastic worth that. None. I can go the Prusa route for much cheaper hands down. Besides, if I’m aiming for firmware compatibility with the Prusa i3 MK3S then i don’t want the same LCD screen that Lulzbot uses anyway.

New Electronics Einsy Rambo 1.2b Board for Lulzbot Mini with Prusa Bootloader from Ultimaker

I chose to get my electronics, the Einsy Rambo 1.2b and the LCD screen from U.S. sources rather than China because for me i not only wanted these quickly, but because i want peace of mind. I dont want to worry that the chinese engineers have replaced the trinamic stepper drivers with something cheaper or other cheap components and hope that they do not fail after 30 days of use. Plus the trinamic stepper drivers is one reason i wanted to upgrade the mini rambo board in my Lulzbot Mini in the first place. I want all my 3D printers to be as quiet as possible, and that is why i want trinamic stepper drivers.

Prusa Mini: First Prints with Ninjaflex

Since getting my new Prusa Mini I’ve been using it mostly for printing with ninjaflex, believe it or not. My homemade lulzbot mini was able to print nylon but i was never able to use ninjaflex (without buying or making another printhead capable of doing so). I do plan to do that at some point, but the new Prusa Mini was advertised as being FLEX capable. And that is one of the main reasons i chose it. That and the flex build plate. And because Prusa is a trusted brand, and it was cheap, and Lulzbot let me down and went down in flaming ball of smoke more or less. Thanks Jeff Moe.

Some have said that a bowden-style printer, which is what the Prusa Mini has, are generally not friendly when it comes to printing flexible rubber filaments. I can now see why, as they are harder to feed through the long tube without the filament having issues. Despite this i have been printing very well with flexible filament, and using clear Ninjaflex specifically.

The Prusa Mini does not have a dedicated filament profile for ninjaflex, presumably because ninjaflex is on the very stretchy side of the TPU filament line and is the one most likely to cause issues. Despite this i have figured out how to use it without major issues. The only issues i had were when i was first feeding the filament into the extruder and setting the layer height on the first layer. In the prusa slicer i just picked the most detailed setting and the slowest setting possible under the generic FLEX filament settings. These seem to work okay actually.

In order to feed the Ninjaflex into the extruder i had to first take off my filament sensor module. With the filament sensor removed i fed the nijaflex through it first and then proceeded to insert it directly into the bowden motor. Once the motor had grabbed onto the ninjaflex i was then able to press the filament sensor back on and finish calibrating the first layer. I did run into an issue when i was trying to purge the PLA. At one point the ninjaflex got pushed too far past the feed screw and got stuck. I had to back it off and try again once i noticed it stopped feeding properly. Other than that the only other issue was calibrating the layer height properly so it would stick to the bed. Early on i had it set too far away from the bed to stick fully.

The first layer calibration for a smooth PEI plate for PLA was -0.650, and -0.875 for Ninjaflex on a textured bed plate. I heard the textured bed plate was designed specifically for flexible filaments and eliminating glue sticks so i got myself one. It seems to work really well, so i have no complaints. Way easier than the glass bed with PEI on my Lulzbot Mini. The fact that i have a smooth bed and a textured bed is not a bad thing since i will be upgrading / modding my Lulzbot Mini soon to have the exact same build plate the Prusa Mini is using. In fact, some of these Ninjaflex parts are for that exact Lulzbot Mini modification.

The reason I’m using clear ninjaflex material is because i am also modifying a bumble ball toy for my new 5 month year old daughter. I am planning on recreating something similar to the toy found in Star Trek Voyager: Friendship One. The one that lights up and plays a child rendition of Vivaldi’s Spring. After printing one test bumper and then tweaking my model i think the new print has come out very well. My prints for the prusa mini bed plate adapter for the lulzbot mini have also come out well, i am just waiting on some threaded standoffs so i can proceed with that mod / project. More updates on that to follow soon.

All in all I’m happy with my new Prusa Mini. The bed size is great, i have no stupid leveling washers to worry about, the bed is flexible to remove prints easily, and the machine is very capable for a decent range of filaments. Nylon would be nice, but with the almost inability to print with ninjaflex i probably wont push my luck.

Coming Soon! Post Preview: Lulzbot Mini – Prusa Mini Hybrid flexible bed upgrade!

This is a preview for an upcoming post and likely a series of posts about my progress for upgrading my slightly broken, slightly defunct home built Lulzbot Mini into a Lulzbot Mini – Prusa Mini Hybrid!

The short version is this: 1. I have an out of tune Lulzbot mini with a cracked glass bed with PEI. 2. Honestly i’m over the glass bed and would prefer a bendable bed like the new Prusa Mini. 3. Lulzbot left my city because of near bankruptcy and poor management leaving behind a lot of people without jobs. So I’m a little miffed at that. 4. It costs less to buy the spare parts for a Prusa Mini bed system and ship it here from Europe, than a new modular glass bed from Lulzbot. Sad. And 5. Lulzbot literally wont sell me a new aluminum bed plate so i can upgrade my mini to a Lulzbot Mini 2 (not sure i really need it, but i want it).

So, Yeah.

I got my new Prusa Mini 2 days ago. 🙂

I got my Prusa Mini spare parts bed today. 🙂 This IS happening. I don’t know how it will all go, but it WILL happen. I built my Lulzbot Mini from scratch. I’m fairly certain i’m one of two, maybe three people who have attempted to do so. If anyone can pull this off, i can. My name is Andrew Barney, I live in Loveland, Colorado, and I’m the random dude on the internet who is going to stick it to Lulzbot and basically more or less convert my Lulzbot Mini into a Prusa Mini.

p.s. here is the response i got from Lulzbot after waiting patiently since November 17th, 2019 for a reply!

Here is my original question:

Is there anyway to buy the aluminum build plate for a lulzbot mini 2? It is not currently listed on your website as a part for sale. I am still interested in possibly upgrading the build plate of my mini series 1 to have the new flipable PEI / bare glass bed.

This is the reply i got back on Apr 30, 2020, 12:23 PM:

John (LulzBot)

Apr 30, 1:23 PM CDT

Hello Andrew,

Unfortunately no.

Best Regards,


LulzBot Customer Care

Literally the worst customer service ever. I used to really like lulzbot. I really did. I never thought they were the best, but they were pretty good and open source and local, and a top leader in the 3D printing community. Sadly Jeff Moe ran it into the ground and left many people here in my town high and dry and without jobs or compensation or proper notice. And that is breaking the law when they knew for months they were treading water. Shady shady practices. Jeff Moe, you should be ashamed of yourself.

Anyway, sorry about the rant and the strong feelings i have towards a company i used to like A LOT. Oh well. They did not leave my town amicably anyway. As a former leader in the open source hardware arena, Lulzbot you really let us down.

But for those of you who already have a Lulzbot Mini, stay tuned for an exciting and much needed upgrade (or multiple upgrades)! When companies refuse to make the product you really want and keep ignoring what their customers really want, then time to hack and build it yourself!

Peas 2020 and other musings

So it seems that i have not updated my blog in quite awhile. Which is a shame really because a lot has happened and is still happening. Plenty of things people would find interesting. So rather than update you on everything I’ll plan on making little posts for each topic / update. (especially because i don’t have all my pictures on the computer yet).

For all you gardening / plant breeding enthusiast i will have a lot of interesting updates for you this year. Some interesting happenings include me working with a lab at Colorado State University. We are working hard to develop low cost open source soil sensors and a system for automatic garden / farm monitoring and irrigation use. VERY cool! I’ll probably put a post about that next!

For you 3d Printer enthusiasts i will have some interesting updates as well. I’ve got my new Prusa Mini on it’s way and should be delivered this week! In addition i have decided to fix / upgrade my half broken Lulzbot mini into a Lulzbot Mini 2 / Prusa Mini hybrid! I’ve already ordered the parts for a prusa mini flexible metal print bed to replace my broken glass print bed on my Lulzbot Mini. I will also be working to build my own Prusa i3 MK3S as well.

And for you computer, techie, and robotics enthusiasts you are in for a sneak peak of what i am doing at my day job. Should be a really treat. So stay tuned you guys. 🙂

As for Peas, Beans, and Gardening things: I have built myself 2 okay-ish raised beds here at the rental property. I’ve planted 8 rows of peas in half of the tall one, tomatoes, peppers, lettuce, and purple basil in the other half.

10 plantings of watermelon / citron-watermelon hybrids (and one heirloom cantaloupe from texas Charley’s Pride Melon) in the short bed. And Purple Snow Peas and my Red Podded Peas and heirloom beans in the other tiny garden spot. I will be breeding the red podded peas (that don’t taste good but look great) with the purple snow peas that taste amazing. I also wanted to select the red podded peas that had the hyper-tendril (semi-leafless) as well so i planted my red podded peas in a root trainer. Sadly i see zero hyper-tendrils. So i will probably just have to select which plants look the healthiest and plant those.

Mini Antique / Vintage Style South Bend Lathe in CAD and future DIY build

So life is busy. VERY busy. I start a new job on Monday as a CNC Machinist. Which is good. I need a job. and the money. And i shouldn’t hate it. I’m actually qualified, but i don’t feel qualified, and no idea what to really expect. Nervous. I guess you could say i’m nervous.

And i’m getting married in a month. yep. scary. Way scary. I guess i shouldn’t be freaked out, but i’m more than freaked out. It’s freaky. yeah. it is. And the worst part? People don’t really advertise that it might be normal to freak out. ‘Cause i mean, it could be normal. But i don’t feel normal. I feel weird. like i’m the weirdo in the room. Bleh, It’s terrible. argh.



So yeah. In other news, i really want my own machine tools. But i don’t exactly have a ton of cash to spend. I’m thinking about trying to build my own gingery inspired mini lathe. I mean, honestly, a Chinese made mini 7″x14″ Grizzly brand lathe is pretty affordable as lathes go and at least usable for the money. And most people would argue that if you make your own lathe from scratch you don’t really save much money and the machine you end up with is crap and has terrible runout and tolerance. And you know what? they’d be right on all counts. But you know what? I’m probably going to attempt it anyway for a few reasons. 1. i don’t exactly have the permission of my fiance to spend that much right now, and 2. i think i can sufficiently cut enough corners to get some sort of working machine. Which is really all i want so i can scratch this itch. Plus making things like this yourself really teaches you a lot you can’t get otherwise. Like when i build my own 3d printer from scratch. It actually cost me a bit more than just buying one, but in the end i know my printer inside and out. And i learned a lot along the way. Like A LOT!

And recently I’ve been greatly inspired by the Makercise videos by Cressel Anderson. It just goes to show you that it IS possible. All thanks to this dude who is not afraid to fail or give up or listen to the nay sayers.


So, yeah. I’m currently designing my own gingery hybrid lathe. I don’t have pictures of it yet, but i may come back and edit this post when i do. It incorporates some gingery simplicity with some better design ideas i picked up from the vintage south bend lathe blueprints i modeled up in Solidworks recently. It was actually really fun to draft up a lathe from scratch. I even posted it on GrabCAD for those of you who are interested.



large (1)

Exploring “Crazy” Watermelon Genetics

The other day there was an interesting discussion about watermelon genetics that started on the Alan Bishop Homegrown Goodness plant breeding forum from a fellow who lives in Australia. Turns out Watermelon genetics are sort-of complicated, but interesting.


Approx. Watermelon Flesh Color Spectrum, from most dominant to most recessive.

The discussion started by asking about which traits in watermelon were dominant, mostly referring to flesh color but also open to other traits as well. The original poster mentioned that he started his own mass cross of over 30 watermelon varieties together (a grex) in preparation to developing his own landrace adapted watermelon to his Australian climate. He said this past season he planted only the seed for any F1 hybrids from any yellow fleshed watermelons he had but got about 90% red fleshed watermelons and concluded that obviously red-fleshed watermelons were dominant. The interesting thing is they are BOTH dominant AND recessive at the same time! Yes, watermelon genetics is a little complicated to say the least, lol.

Wait… what??!… haha yes, you did read that last sentence correctly. Red-fleshed watermelons are both dominant to yellow-fleshed watermelons AND recessive to yellow-fleshed watermelons. Turns out there are actually TWO different kinds of yellow-fleshed watermelons.

Watermelon Flesh colors range from various forms of red, pink, yellow, orange, and white. So how does one figure out what is recessive and/or dominant over what? Turns out most of these have already been studied and we can interpret that data. I’ve recently resurrected my old website domain and turned it into a plant breeding wiki of sorts. Feel free to check it out @ The main resource i am using is the wonderful watermelon genetics info posted online by the Cucurbit Genetics Cooperative hosted by North Carolina State University and in particular Todd C. Wehner part of the Department of Horticultural Science at North Carolina State University.


From the data available we can come up with a rough basic pictorial based diagram. I like pictures; they help me understand things better. Basically there are at least two types of red-fleshed known as “Scarlet Red” and “Coral Red” in addition to two forms of yellow-fleshed known as “Canary Yellow” and “Salmon Yellow”. Turns out Canary Yellow is dominant to all other forms of color. Scarlet Red is dominant to Coral Red, Orange, and Salmon yellow. Coral Red is dominant to Orange and Salmon Yellow. Orange is dominant to Salmon Yellow. You get the point. And basically seems to work in a cascading effect of “more color” to “less color”.

I personally prefer the taste of the Canary Yellows over most red/pink, though there are still some good red ones out there! What i don’t like are the Salmon Yellows (and maybe orange). To me and in my climate the Salmon-Yellow watermelons have a weird mealy and/or mushy texture and have a muted / poor flavor. By contrast the Canary Yellows seem to be really sweet and might even get sweeter more easily / earlier in a northern and colder climate like mine. That is just my personal preference, your taste buds and soil conditions may differ.

Now this is a general simplified version. There are a few caveats however. Such as the fact that there is a Canary Yellow inhibitor gene that when present will turn a Canary Yellow back into a red that is hiding underneath. Also the fact that there may be a few other minor colors that have not been studied yet such as “dark red“, “rose” , and “pink“. It is possible that these colors are just minor variations of the former reds and function the same way from “more color” to “less color” in terms of dominance. It is also possible that if these are indeed separate shades of color that they may buck this trend and function in completely different ways from different biochemical pathways. Hard to say at this point. But i will leave the possibility open either way in case new studies in the future address these watermelon flesh colors.

Oh, and what about white-flesh?! Yes that’s right, we have completely forgotten to talk about white fleshed watermelons. Oh, you didn’t know there were white-fleshed watermelons? Yeah there are. They are not generally as common but there are white fleshed watermelons out there. Turns out white-fleshed is a little more weird. Let me explain.


F2 Generation of White-Fleshed Watermelon Genetics


White-fleshed watermelons are currently being studied more in depth in China and a new paper is due any time in the near future. But until then all we have is the data gathered already from a past study on it. According to that study: white-flesh were found to be dominant over all color. In an F2 (Second Filial) Generation the ratio is: (12 white : 3 canary-yellow : 1 red).

Pretty interesting huh? Yeah, basically if i interpret this information correctly is that for whatever reason white flesh overrides color. In the wild, watermelons were originally thought to be white fleshed and low in sweetness. This is certainly the case in the wild citron melon (Citrullus lanatus var. citroides) which has hard white flesh and bland flavor. The bitter apple melon too (Citrullus colocynthis) but it obviously is very bitter.

The genetics for watermelon at this point captured my interest so i decided to find out what i could about seed coat colors. If you thought watermelon flesh genetics was complicated, you’ll find the genetics for watermelon seeds is a nightmare. Nevertheless i waded knee deep into the confusing data and came up with some generic info that i think can give us a basic trend that we can use.


Approx. Watermelon Seed Coat Color Genetics

The genetics for watermelon seed colors and patterns is a nightmare. Truly it is. Partly because the studies we have don’t all agree and we don’t have examples of what these old researchers were really studying. One person’s “tan” might be another persons “light brown”, etc. You get the point. Very subjective. But based on the studies we have it basically looks like in general there are three genes working together and we can come up with a basic trend that we can follow.

Basically black seeds are dominant to other colors. Brownish or greyish seeds with a particular black mottling striping with black dots is next in line. Tan or brown seeds are probably next in line. Green seeds (not pictured here and rare) are dominant over red. Red seeds are the most recessive except for white. White seeds are the most recessive and recessive for all three gene combinations. This is a very simplified interpretation and there are probably actually more than three genes. In my population i have grey seeds which is not a color that has been studied. Also i have no idea what “tan” actually is so i lumped it in with brown. Brown too has not been studied, nor has “reddish-brown” among others.


Watermelon Fruit Shape is Co-dominant. Elongate (OO), Oval (Oo), and Spherical (oo).

Watermelon Fruit shape is relatively simple however. Yay! Simple co-dominance at work. Two long genes (OO) give you long fruit. One long gene and one round gene (Oo) or heterozygous gene pairs give you medium oval shaped fruit. And two copies of the other round gene (oo) gives you round spherical fruit. Easy peasy!

Golden-rind fruit are easy genetics too. Simple recessive (go). This is a trait more common now as it helps people identify when a watermelon is ripe. They turn bright yellow when ripe.


Yellow-rind fruit are recessive (go). Fruit become golden yellow as they mature.

And the last trait i will mention is the “explosive rind” trait.

Haha, it’s not as scary as it sounds, but it’s not particularly a trait you want in your watermelons. Fortunately it is recessive and hopefully you wont encounter it in many varieties. I’ve seen it in the unusual striped variety but fantastic tasting ‘Osh Kirgizia’ watermelon, but otherwise not that much. Officially explosive rind (e) causes the fruit rind to burst or split when cut. This is true, but i also find that often when this trait is present the fruits themselves have a higher rate of splitting open while ripening on the ground and even when you lightly grab one to harvest. Not a trait that a market grower would want. For a small backyard gardener it’s not a huge deal as you can eat them right away, but still a slight inconvenience, especially if they split in the field and ants get to them. Black ants really do love sweet watermelon flesh.

Watermelon split

The recessive explosive rind trait (e) causes watermelon fruit rind to burst or split


Wild Galapagos Island Tomatoes and the Secrets of Diverse Wild Tomato Species


Solanum Cheesmaniae, “the” Galapagos Island Tomato.

Like Corn (Maize) and it’s ancestor Teosinte, Tomatoes have wild relatives as well. And what a variety of species they have too! My love and interest in growing, observing, and breeding with these wild tomatoes, like tesosinte, is only continuing to grow.

The wild tomato that I learned about first, and led me down this path, was the almost mythical “Galapagos Island Tomato”. From the same famous islands visited by Charles Darwin in his expedition to catalog biological diversity in all it’s forms. And what better place to start learning about wild tomatoes than from the Galapagos Islands (Ecuador), an enchanting place steeped in biological diversity.

There are actually two main species of native Galapagos Island tomatoes, Solanum cheesmaniae and Solanum galapagense, and they are closely related. Originally, S. galapagense was thought to just be a subspecies of S. cheesmaniae, but was later discovered to be a separate species fairly recently by Sarah Darwin, the great great granddaughter of Charles Darwin. Interesting to see a family legacy of scientific inquiry passed down, but also somehow fitting.


One form of Solanum cheesmaniae leaves and growth pattern.

Both forms are said to be quite salt tolerant (S. galapagense in particular) and may posses some disease resistance. But they also still retain many traits in common with domestic tomatoes and are easily crossbred with them. This salt tolerance is one reason why these tomatoes are so sought after for introgression into modern tomato varieties. Crops that can survive in the harshest of climates and that could be watered with sea water rather than the worlds increasingly limited supply of fresh water is one high area of worldwide interest.


Solanum galapagense, small orange hairy fruits.

Both S. cheesmaniae and S. galapagense are very different in appearance and traits despite both originally thought to be the same species, though similar in many respects. I find the scent of S. cheesmaniae leaves to be of a mild lemony scent but with a strange overtone along with it. The smell of S. galapagense is much stronger with still a sort of lemony smell but a very pugent after odor as well. One person i talked to went to the extreme as saying it smelled like “burning garbage”. Haha, i wouldn’t go that far, but it is an odd smell indeed. Not exactly pleasant.


one example of typical S. galapagense leaf shape and typical sickly yellow appearance.

S. galapagense is of particular interest because not only does it have salt tolerance as well (if not more so that S. cheesmaniae), but it also has unique pest resistance to the common whitefly, a major domestic tomato pest that can spread disease and decimate tomato crops. Solanum cheesmaniae however does not contain this resistance to whitefly, nor do many of the other wild tomato species either. And of those rare few accessions that do, S. galapagense beats them hands down. This is due in part by two factors. One is that it is densely covered in type IV glandular trichomes, or hairs, while simultaneously producing volatile acyl sugars which help repel insects. A sort of bug repellent and/or insecticide. Pretty cool, huh?


Additionally S. galapagense is the more interesting species anyway, by way of genetic diversity and divergence from domestic tomato DNA / genomes. According to one study, that compared to the DNA of S. galapagense, S. cheesmanie, and domestic tomato S. lycopersicum, they found that S. cheesmaniae shares 71.5% of DNA markers with domestic tomatoes, while S. galapagense only shares 57.6% of it’s DNA markers with domestic tomatoes. With only of about 50% DNA markers being shared between S. cheesmaniae and S. galapagense.



Distribution map for S. cheesmaniae and S. galapagense on the Galapagos Islands.

A map of the distribution of S. cheesmaniae and S. galapagense shows that S. galapagense is not present on the eastern islands. This has led to speculation and conflicting data about the origins of both species and evolutionary distribution on the islands. One study suggests a colonization from east to west , from older to younger islands, supported also by the fact that ocean currents average an east-west direction. If the colonization of Galapagos Islands was east to west, then S. cheesmaniae could be an older species than S. galapagense, and could even be an ancestor to it.

However, high diversity in the S. cheesmaniae group and its correlation with the islands of origin were also suggested. This indicates a possible influence of the movement of the islands, from west to east, on the gene flow, which is the opposite direction. And the lower genetic variation in S. cheesmaniae found in the older islands could possibly be due to a founder effect, and colonization could have happened from west to east. If this was the case, S. cheesmaniae and S. galapagense could have diverged around the same time from the same ancestor. So in short, while that is all fascinating speculation about whether S. cheesmaniae is descended from S. galapagense, or S. galapagense is descended from S. cheesmaniae, or whether they both diverged from a common ancestor we just don’t know. I personally am inclined to believe based on the evidence (until further studies come forth) that both diverged from a common ancestor and moved east to west. Older populations of S. galapagense could possibly have been eradicated on the eastern islands from continual volcanic eruptions and S. cheesmaniae could have been reintroduced onto the eastern islands by traveling animal species. We just don’t know.

One word of caution though if you decide to go looking for seeds for these Galapagos Island tomatoes. You almost certainly wont find pure S. cheesmaniae or pure S. galapagense seeds out there except direct from a seedbank. There are a LOT of snake oil salesmen out there that claim to have them, but while it is possible that they have some wild galapagos tomato heritage, these varieties are almost certainly not pure. Some may very well have S. cheesmaniae ancestry, but are not pure. I have yet to grow out many accessions of S. cheesmaniae and access the genetic diversity in the species, but one that set fruit this last season was about the size of about the nail of my ring finger. Super tiny. One way you can tell if they might be authentic is if the seeds themselves are incredibly small. But if they are the same size as regular tomato seeds they are not pure.

Both S. cheesmaniae and S. galapagense seem to be day length sensitive and only set fruit for (like some of the other wild tomatoes and hybrids) at the very end of the season in August-September. Some did not set fruit at all. A common myth of the Galapagos tomatoes is that they are hard to germinate with the reason being that they evolved to pass through the stomach of a tortoise before germinating. It is true that they are some-what hard to germinate, but they are not impossible to germinate without treatment with bleach or acetic or tartartic acid.

Germination is variable in this regard, and considering that not all islands where S. cheesmaniae and S. galapagense are found, don’t even have tortoises that visit them makes this supposition seem dubious at best. There could be some adaption to the islands in regards to germination, but i am inclined to believe at this point in time that it is an adaption to the soil with high volcanic ash (and thus high pH). After all, many if not most of the accessions of these from the TGRC directly mention that they were growing out of cracks in lava flows. A coincidence? I think not. Recommended seed treatment 50% bleach 50% water does indeed help germination a bit, but it is also recommended to prevent disease and seed borne pathogens. I suspect even soaking the seeds in plain water or soaking in lemon juice may also help germination, but i have yet to do an experiment that tests this idea.

It is obvious that the Galapagos continues to amaze us with it’s fantastic contributions to biological diversity, but what about some of the other wild tomato species? What secrets do they hold for the future of tomato breeding and future tomato varieties? It turns out a lot. Quite a lot actually.


LA1777, Solanum habrochaites fruit, photo by Joseph Lofthouse.

Solanum habrochaites is the next species that researchers are paying attention to. It is from Ecuador and Peru in South America. It is hard to cross with domestic tomato lines, though not impossible, generally through one-way crosses by using the wild parent as the pollen donor and the domestic parent as the pollen recipient. It turns out lots of domesticated plants work this way, having lost the pickiness of their pollen receptors, while wild species are very picky about what pollen they accept.



Solanum habrochaites, bold floral display. Photo by Joseph Lofthouse.

S. habrochaites has lots of genetic diversity within it’s species clade. One, like the most commonly requested accession, LA1777, is a unique off-type. Compared to the rest of the species of S. habrochaites, accession LA1777 has been classified as unique and having genes that may be desirable for introgression into commercial tomatoes.

LA1777 tends to grow small delicate and wispy. The stems on LA1777 are thin and only a couple feet long. The stems on other habrochaites accessions are thick, and grow 4 to 6 feet long. The stem on LA1777 is fibrous. The stems on other accessions snap when bent, like one might snap a young green bean. The leaves on LA1777 are smaller than other accessions.

LA1777 has an unobtrusive floral display that gets lost in the foliage. The floral displays on the other accessions were bold and carried high above the foliage. LA1777 is reported as having better tasting fruits, and not as much brown coloration in the fruits. And though it is reported as being Self incompatible (SI), it somewhat behaves as if it is Self Compatible, at least to some degree. S. habrochaites has both Self-Incompatible and Self-compatible forms.

It is sort of ironic then that LA1777 is the most requested accession of S. habrochaites from the TGRC even though it does not represent the species very well as a whole. However this may be explained by the fact LA1777 has become sort of standard accession in university research and published articles reflect that. But also from the research being done by big seed companies as well. One of the big seed companies tested LA1777 and found one unique gene that nearly doubles production of commercial tomatoes when it is introgressed into breeding lines. Between the university research and the seed companies, LA1777 has become the standard variety for most research on this species of tomato.

But caution should be noted as there may be much more diversity and worthwhile genetics in S. habrochaites than in just accession LA1777. I find it to be poor research that most of these published university studies have ONLY used ONE accession in comparison to domestic tomato varieties, namely accession LA1777. Shame on them.


LA1777 on left, F1 hybrid on right. Solanum habrochaites outlier accession.


Solanum habrochaites, photo by Joseph Lofthouse.


Solanum habrochaites, photo by Joseph Lofthouse.


S. peruvianum illustration, year 1828.

Solanum peruvianum is a well known and highly interesting wild tomato species. It’s name obviously hints at it’s origins being from northern Peru and Chile. Solanum peruvianum was originally thought to be a very diverse species of wild tomato, and it still may have much diversity, however it recently has been reclassified into four separate species: Solanum peruvianum, Solanum corneliomuelleri, Solanum huaylasense, and Solanum arcanum.

Solanum peruvianum has purplish fruit when ripe, along with green stripes similar to S. habrochaites. The fruits are said to be fruity and pleasant tasting when fully ripe, but not before. S. peruvianum is said to be harder to cross with commercial tomatoes. However, by using a bridge species that is more readily able to cross with domestic / commercial tomatoes it is said to be possible to move the S. peruvianum genome into the domestic tomato genome.


S. peruvianum flowers, highly attractive to solitary bees in North America. Photo by Joseph Lofthouse.

S. peruvianum might have interesting genetics for it’s fruit characteristics and sugars. It also is said to contain some salt tolerance and ability to grow in harsh areas unhindered. It is also resistant to the tomato leaf curl virus. S. peruvianum is a mostly outcrossing species (Self-incompatible), with some Self-compatible accessions known and collected from isolated specimens. It seems to be fairly drought tolerant in my experience.


One of two species of bumble bees that loved Solanum peruvianum flowers in my garden, Colorado, USA.


S. chilense, flowering

Solanum chilense hails from the desert regions of southern Peru and Chile and hasn’t had much research attention paid to it, and thus i don’t have very much information about to share. However it has had some, and it has three main claims to fame. The first is that it is often cited as being a bridge species for S. peruvianum, and other distant species such as S. sitiens and S. lycopersicoides.

The second is that is said to be quite drought tolerant, having a unique root system unlike the other species that allows it to have a very deep root structure. In a desert environment having a deep root structure could be invaluable for surviving rough times.

The third is that this species supposedly has anthocyanin colored fruits and contains the “Aft” gene. The “A” gene being the gene that codes for anthocyanin production, and the “ft” referring to fruit. Haha, simple, but effective terminology.

The Aft gene has been introgressed from S. chilense into domestic tomato breeding lines and is directly responsible (in conjunction with other anthocyanin introgressed genes from S. cheesmaniae) for those new “Blue Tomatoes” you have been seeing on the market now. ‘Indigo Rose’ being the first official tomato variety of this kind. Indigo Rose, was developed from the Oregon State University tomato breeding program. The P20 blue tomato was a leaked breeding line from OSU that eventually became ‘Indigo Rose’. Indigo Rose was released after it was clear that many tomato breeders were already using P20 to breed better tasting blue tomatoes. ‘Indigo Rose’ does not have the best flavor as do most blue tomatoes at this time, but that is steadily being changed as more tomatoes are bred and crossed with each other for better flavor.


The ‘Aft’ tomato (LA1996), growing in N. Colorado in 2017.

This last year, i had the opportunity to grow one of the precursor blue lines to ‘Indigo Rose’, LA1996, which is a determinate tomato, bears fairly large fruit, and has the Aft gene for anthocyanin fruit. LA1996 however does not have blue tomatoes, but rather a dirty blue speckled appearance. I kind of like it though, and i found it to be one of the few tomato varieties to do well in my garden, so i am keeping it. A great tomato variety for me. I have simply just been calling it ‘Aft’. Haha, not very original, but i don’t care.


Solanum pennellii, a wild tomato species from Peru, with waxy leaves that help with drought tolerance.

The next species that holds great promise is Solanum pennellii from the dry regions of Peru. This species holds a wealth of potential genetics that domestic tomatoes could benefit from. The first is it’s small unique shaped leaves. These leaves also have a unique thick waxy coating on them that has been shown to help with conserving moisture and providing one form of drought tolerance. This is a completely different desert / drought tolerance adaption than S. chilense’s root structure, how exciting!


Solanum pennellii flower close-up view. Notice how it has loose anthers and a unique curved and exerted stigma.

The excitement for S. pennellii does not end there however. Next notice the flower structure of this species. S. pennelli has both Self-Compatible (SC) and Self-incompatible (SI) forms, though the SI forms are more common. Like, S. habrochaites and many of the other wild species, This self-incompatibility or mandatory-outcrossing nature helps to ensure maximum genetic diversity within the species as possible.

The self-compatible species, including Solanum lycopersicum – the domestic tomato, Solanum pimpinellifolium, S. cheesmaniae, and S. galapagense, all have small uninteresting flowers with tight flower structures, non-exerted stigmas, and closed anther cones which make it hard for pollinating insects to visit them or make it worth their time.

This combination of large open flowers, exerted stigma, and unconnected anthers in S. pennellii make it very attractive to solitary bee species, including small Colletidae bees, Halictidae bees, and of course various species of bumble bees.

Solanum pennellii however has been praised in articles as being the most interesting species of wild tomato to work with because of unique acyl compounds. Basically the compounds that contribute to scent and flavor in fruit. Some Acyl sugars can be astringent and bitter, but some can contribute significantly to pleasant traits as well. Since S. pennellii differs from the common cultivated tomato quite significantly in this regard it is a highly interesting species to work with as it may lead to new tomato flavors and smells. I would regard S. pennellii to be the nicest smelling tomato species i have worked with yet because many of the F1 and F2 hybrids between [S. pennellii x domestic tomato] neither have the standard smell of domestic tomatoes, nor the sometimes stinky smell of some of the other species, instead on average S. pennellii hybrids smell quite like lemon-basil. A very nice smell for a tomato plant.


F1 hybrid [domestic tomato x S. pennellii]. HUGE monster plant with wide branching growth. Highly attractive to native pollinating bees.

But that is not all! S. pennellii has reported salt tolerance just like the Galapagos species. But unlike the Galapagos species, it has all the above going for it and the fact that it’s hybrids grow HUGE! I mean HUGE monster plants. The combination of domestic genes with various desert tolerance in S. pennellii in hybrids make it a formidable plant and a great one to use as rootstock. In my climate here in Northern Colorado, where most varieties of commercial tomatoes fail to thrive in my soil and dry atmosphere, S. pennellii hybrids THRIVE! a testament to their will to survive. A badly needed trait in my own tomatoes here.

And finally, the last two wild tomato species i am going to mention are Solanum sitiens and Solanum lycopersicoides, two tomato species unique within the tomato clade. These two species, while probably having other traits in common with other wild tomatoes such as possible drought or salt tolerance, or disease tolerance, or blue fruits (S. lycopersicoides), their real uniqueness lies in the scented flowers they carry.

In all the groups of the domestic and wild tomatoes, none, other than these two species carry scented flowers. Perhaps a trait lost long ago and never really needed. Whatever the case may be, these two distant species carry scented flowers to attract various pollinating insects. S. sitiens flowers are described as stinky and volatile, with a “mothball-like” odor. Presumably this scent works best at attracting flies or beetles which may prefer the stinky smell. S. lycopersicoides on the other hand has flowers which are described as sweet and nectar-like, presumably to attract various bee or moth species that collect nectar. Studies between these two species and the distinct pollinators that visit them would be quite fascinating, especially when put into the subject of adaption, diversification, and evolution.

Breeding domestic tomatoes with wild tomatoes is a slow process. But it is interesting and the amount of segregating diversity is endless. Here are some photos of F1 tomato hybrids, F2, and various Back-crosses and segregates.

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Oh, and p.s. before i end this post, please note that i have started an experimental plant breeding wiki on my test website. I don’t claim it to be very good, but i am working on posting good pictures of wild tomatoes so that i can have a good reference to look back on to identify specific tomato species and the traits they have. Nobody other than myself will probably find such a wiki useful or interesting, but if for nothing else i want it for myself. There is currently extreme outdated or spotty, or missing info about these tomato species on wikipedia currently and the web is scattered with various information in little nooks and crannies. I wanted a central location that was easy to find. Hence, my tomato wiki.

Feel free to create an account and add your own photos or corrected information or cited sources to the wiki. The more people that help, the better it will be. The more photographs of various diverse species and accessions and angles and growers will also help a tremendous amount as well. Thank you.

Calling all Electronics Wizards and Open Source Hardware enthusiasts to help me fix my Motor Controller…

Okay. So, i’m a little embarrassed that this thing is still not working. I’ve made cool progress on it over the years, but not the part that matters… that it actually works. This should not be that hard. Since it’s basically an HIP4081A beefy full h-bridge controller and an Arduino it should not be all that complicated. I think what i need to do is just spend some money on known good components and true schottky diodes and mosfets and just breadboard this thing out. Once i can get this reliably working on a breadboard i can come back to the PCB design stuff. I know last time i messed with it i had a few PCB wiring issues and when i was testing the h-bridge i could only get one side to turn on. The other side was shorting out somehow.


Having said that, i’m still pretty happy with the overall PCB design and direction that is heading. I really enjoy the two PCBs that plug into each other via male and female headers ans sockets. I just put up my files (in their old unkempt state) onto GitHub for version tracking and in true Open Source Hardware fashion for others to hopefully help collaborate with me on this. I really really really want to see this thing work someday and turn into a cool motor controller that people use all over to build cool robots and stuff with in the near future.


So, please… If you are good with electronics and electronic theory, especially motor control, if you are an open source enthusiast, if your good with git, if you are good with EagleCAD, if you have an interest in a cool Open Source motor controller based on MOSFETS, if you were a user of the old FIRST Robotics, VEX Robotics, or IFI Victor 884s or 885s that this design is based on (now a defunct product to my knowledge), if you’d like a motor controller you can hack, use I2C or add a CAN bus or some other device such as a current sensing circuit, or who knows what else, then PLEASE PLEASE Help Me! Help me get this thing working and ready for market and usability and hackability. I’m not ashamed to ask for help or to admit that i need it. I’m proud of how far i got with as little electronics knowledge as i do have, but concede that there are so many other people out there that can help!




I have uploaded the last freeze of this project onto a new github project for you all to easily get the source files here:

I’ve also designed a neat little 3d printable base to keep this thing from shorting out. And i will track down the other design files that are relevant or that this design is based on in the next couple days / weeks.



*Bonus Offer: I have several old PCBs of V. 1.0 laying around. For anyone willing to help me with this project i would be willing to send you up to 3 copies of the top and the bottom boards each to play with (while supplies last). There are i think at least two potential PCB trace errors (that i can’t remember what at the moment) that are on the boards, but hey, free boards and it’s not that hard to cut a trace or two and rewire if needed. You would just need to obtain the needed mosfets, diodes, arduino, and HIP4081A h-bridge driver chip to work on the project. Heck, i’m even willing to entertain replaccing the HIP4081A chip to a different one if there are any better or cheaper options that do basically the same thing. Please Help 🙂