Let's Make Robots!

New laser cut robot chassis for GM series motors

test bed for GM motors - currently sonar / avoidance
ROUNDBOT7_17_08_with_reverse.BAS2.12 KB

Well, I got busy tonight and designed a chassis for the GM series of motors. The GM motors are really tops with price/performance... at $5.50 each, they are VERY hard to beat.

I thought you might like to see a video of the chassis being cut out, so it's included. The material is plexi .093 thick - it's clear, but has a blue protective plastic coating designed to protect it durring cutting and handeling - plexi scratches easily.

I designed this because there are absolutely no good chassis for the GM series motors, and that's a shame because they are so nice.

I've got to mount a few more parts, but it should be done over the weekend. Thanx to Fritz for sending me some code to build on :-)

Everything has a solid mounting point on the chassis (screws) and the servo is a fuill size JR ST47, mounted off center so the shaft is centerline preventing cone errors durring scanning.

I started out as a machinist so I try to make everything with extremely close fitting tolerances and built to last - the deck is screwed together, but the interlocking tabs would hold it together by friction alone. Motors are hard point mounted with screws and add to the rigidity of the chassis.

Just a few more tweaks and I gotta figure out the battery configuration...



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Congratulations great job with the chassis!!!

Regarding the slots that interlock the two pieces of plastic together (gm9 motor bracket and round baseplate) if let say the acrylic is 3mm thick what is the size of the hole to accept it? I assume that due to material tolerances it should be a bit bigger.

Is it possible to have a pdf drawing with dimensions of the chassis for referance? I am trying to do a frosted acrylic cube with interlocking pieces and I don't know how to do the connections? 


Thanks a lot


IT make my ping sensor works. I though I was under power with the 4AA recharchable battery but it work great. I want to put 2 ping sensor on my rc car and so how do I start with that? Do I put both ping on the same pin? or the second ping on pin1 and do high and low for pin1? any advice is greatly appreciated.
Very good. This project is great. It's very fast and the programation it's not too long.

Yep, your right. I need to look at that a bit more...

 I'll try and incorporate some of the code from Fritsl's "project II" robot dealing with the head position of the servo - that should straighten it out.

The current decision routine is rubbish.

what you need to do is just keep a record of the "ping" gosub you went through before. Example:

1- gosub ping 

2- record the ping value 

3- turn head

4- gosub ping

5- is this value bigger than the previous one? if yes we can just keep going this way!

6- record the ping value 

7- etc etc..

 but actually this code supposes that there is no or at least little movement in between those two gosubs.

hey Casca, there's something i don't really understand about your .bas file. it says:

gosub ping
gosub ping2
if W0>W1 then
gosub motor_reverse
gosub body_lturn
gosub motor_reverse
gosub body_rturn
end if


won't the two gosubs (ping and ping2) give the same results as the head hasn't moved between the 2 gosubs?

Great job on the entire thing!  Looks awesome, very sturdy and well though out.  You should be very proud.

BTW: If you are interested in selling a couple oif the SRF05 bracketrs, I would be interested in buying!  ;)

Through Fritsl's generosity, I'll have a web shop hosted on this site very shortly - I should have the text done in a few days. In the mean time, feel free to PM me and I'll be happy to get you some brackets :-)

That is amazing news. Your workmanship looks superb! All I need now is a design... 

Thanks so much for the compliment. Although it won't happen overnight, I'll also post some general guidlines for design, and I think that should help with the learning curve. I'd also be happy to check over a design and try to make sure it'll fit together.

 On a side note, I've been playing with google's "shetchup" over the weekend - there is a free version available, and it offers DWG (autocad) exports as well. The package is quite friendly and in just 2 days I'm starting to get the hang of it... for those who have invested time learning a new CAD package, this is a bold statement to be sure.