# RC Lawn Mower Progress



## CalgaryPT (Oct 5, 2019)

Slow, but at least _some_ progress, with my RC Lawn Mower.

I had originally hoped to automate the deck height on this mower. It took almost two months to get the HD actuator and RC transmitter to talk to one another properly, but I finally got it working. Sadly, as expected the geometry of the mower didn't work out the way I had hoped. The single lever adjustment on the mower I was attaching to the actuator is so far back it interferes with the wheelchair motors too much. In order to make the deck go up and down I have to move the batteries and motors (which are very heavy) behind the mower so far they will tip everything around the rear drive axles. RC deck height was just a cool thing I wanted to try. I feel satisfied that I got the mechanics and RC stuff to do what I wanted, even though it wasn't a practical mod in the end. I could move at least one battery to the front as a counter weight, but because the front wheels are free spinning stem casters on grass, I don't want a lot of weight up there. Also, the wheel base would be so long I couldn't spin around trees easily, which is the primary objective of the whole project.

The good news is that once adjusted, you really don't move the deck height too often of course. So the solution is simple hangers made from All-thread. These will go into 1/2" x 1" oblong punched holes in the angle iron frame to give me some minor horizontal alignment. Posilock nuts will allow for the actual deck height adjustment.

Next up is back to the ironworker for punching, then making the motor mounts. This should be fun as it looks like I will be bending 3/16" plate after plasma cutting. I have a bunch of rusty 1/16" sheet I may prototype with first.

I also may remove the magnetic brakes on the motors; I'm not sure. They are locked by default, so use an additional few amps to keep unlocked when the mower is operating. I had devised a Arduino sketch and a few HD 24VDC relays to auto unlock the brakes, wait a few millisecs, then power the motors, but this just uses up valuable amp hours I may need.  So I will cross that bridge when I come to it.


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## PeterT (Oct 5, 2019)

Move over Binford 9000 Destroyer. The TeslaMower is coming alive!


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## Alexander (Oct 7, 2019)

I have wanted make one of these for over a year. Just haven't found the time yet. I can't wait to see what you build.


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## CalgaryPT (Oct 19, 2019)

A little more progress...this weekend I'm working on the motor mount template.

I think I may punch a series of 1" holes in the sides of these and dimple die them. That will help keep weight down and add some strength. Once the battery tray and overhead support plate get added to tie together the mounts I'll have better rigidity, but I was surprized how strong the 1/8" plate is already, so I'm glad I didn't go heavier.

I love oval punches for the bolt holes—so easy to make adjustments.


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## YYCHM (Oct 19, 2019)

Oval Punches?  Let's see an image of these things and the punch (engine?) please.


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## PeterT (Oct 19, 2019)

Some serious fabbing going on there.
Maybe you mentioned already, but what kind of speed control have you settled on & how does the RC talk to it?


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## CalgaryPT (Oct 19, 2019)

As you wish...

The "punch engine" is a 25 ton Edwards Ironworker—the smallest one they make, but my favourite shop tool. It will do up to 1" in 5/16" A36 steel.


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## CalgaryPT (Oct 19, 2019)

PeterT said:


> Some serious fabbing going on there.
> Maybe you mentioned already, but what kind of speed control have you settled on & how does the RC talk to it?


Speed controller is a Sabertooth 2x60 Amp. It has several input modes, including an RC mode. So you can talk to it directly with a RC receiver. Sabertooths are used in a lot of Battlebots and industrial/military robots. The only thing I don't like about them is that the terminal strips back on to the heatsink, so if your wires/ferrules protrude you short it out and can toast a $250 controller. That's why you see electrical tape on mine as a temporary solution. I'll put something more permanent on eventually.


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## YYCHM (Oct 19, 2019)

What's one of those punch dies worth?


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## CalgaryPT (Oct 19, 2019)

About $50 USD per set (punch+ die). Those are the brand name punches, but you can get cheaper from other companies.


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## PeterT (Oct 25, 2019)

Thought you'd enjoy this picture. Came in the Home Made Tools newsletter. They usually include some picture from the past.


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## CalgaryPT (Oct 25, 2019)

Lol. Thanks.


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## TheLocalDrunk (Oct 28, 2019)

CalgaryPT said:


> About $50 USD per set (punch+ die). Those are the brand name punches, but you can get cheaper from other companies.


Would you trust the cheaper ones?
Scary amount of force in that.
And ironworks kick A$$!


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## CalgaryPT (Oct 28, 2019)

The distributor I bought my ironworker from told me many of the 3rd party manufacturers of punches/dies were just fine. Thinking back I seem to recall when I ordered my original sets, some sizes were unavailable and they sourced from a 3rd party. I think it was American Punch Co. They were about 1/2 the price and they worked fine. I will be ordering a couple of new ones soon as at least one size has 800+ punches on it.

WRT the force—mine will do 1" hole in 5/16" A36 steel. It can also bend 1/4" plate and shear angle, rod, etc. on its second punch station. That's nothing compared to the 12 other models or so they sell. As ironworkers go, mine is the smallest on the market. They make a 120 ton one that will punch a 1.5" hole in 1" steel. As amazing as that is, other manufacturers make bigger ones I think, but maybe not too much bigger, at least for punching. I think there is a physical limit—not in terms of power, but after you go over 1" material, I think you start have deformation issues in the surrounding material at room temperature. 

They are great machines and I am lucky to have one in a home shop. I love the raw simplicity of it: it makes a big snap when the material is punched and there are no computers or programs to go wrong (at least on my little machine). They last a lifetime, so when I downsize in a few years, someone will get a heck of a deal from me.


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