pic: A little CAD practice

After the GREAT season of Logomotion has ended, I have decided to cad a 6WD (due to a little robot hangover). But after leading CAD this year I think I have come along way since the start of this year (from Nov.
http://www.chiefdelphi.com/media/photos/35965) Please critique and comment on this!! I love all the help I can get!!

why make the wheel base so short?

Do you have any tensioning plans on the outside wheels? I can’t really tell, but that is important. It looks very nice, everyone always gets better after the season is over, keep it up.

It’s 37in?

Yes but I donut know how I should go about it, have any ideas?

With smaller wheels, you can distance your wheels more, giving you a longer wheelbase. Note: wheelbase in this case is distance between wheels, not overall length of the drive.

Ahhhh ok, Sorry i was a little confused at first, but ill put it on my todo list.

Floating tensioner (2 lexan strips + 2 bolts+ 2 nylon spacer/rollers)

Nice drawing. Now time to add some holes for mounting bumpers and add bumper supports between the wheels.

Nice Chassis drawing. I am also the leader of CAD on my team. I have seen an improvement on my skills from start of the season to the end. Now, just add more to it. the wheel size is interesting. I have hardly seen small wheels like that on the past robots, but it seems to be a good idea. Keep going.

Since you are already making bearing plates, it wouldn’t be too difficult to slot their mounts in the frame rails and make a true “West Coast Drive” tensioner. Loosen mounting hardware, slide bearing block until chain/belt is tight, re-tighten (works even better with cam bolts or some sort of lead-screw to help keep the block in place once tensioned).

My team has never made a chassis that has the wheels on the other side of the frame. I was wondering how you do this? Is it using a hex shaft or what? Could you possibly explain all of this or maybe put up a CAD design to download or even a close up picture. That way i could see how it works and maybe use a drivetrain like this in the future.

Thanks :slight_smile:

There are a lot of great tensioning systems you could use. Obviously the easiest set-up would be just adding the kop tensioning system. But interesting systems are also around you could look at cam tension systems for the outside wheels. Making the center wheel direct driven would allow only the outside wheels that would need tensioning. I came up with a lot of crazy systems that would all yield the same result. My favorite one used surgical tubing to move the outside wheels farther out. In the end there is no true answer but a endless supply of them. You have all summer, I would say to experiment a little and find a unique solution that is your design. Keep it up.

Stupid question, Theres a KoP tensioning system? because if there is, I would be a very happy man.

I used a 1/8keyed shaft in the picture and I put an E-clip on the end of the wheel to keep it in place.

Do you still want up close pictures?

I actually was thinking of it while sleeping… and noticed that u can use the key slots. Is everything key slot or no. Also how do you make the slot for the E-clip, is it just done on the lathe?

And is the only thing holding the shaft straight the brace on the side of the tubing + the tube?


These came in the KOP I beleive last year I have no idea if they are still included. The design is from RC he is from team 1323 Madtown robotics. I know there are still some issues with them but these may work for you, they are a great design.

Ahhhh those, i did have a few of those laying around the shop for awhile but someone (that is pretty good with had tools) got a hold of it and “changed” it a bit so…i can use them. But i can always ask some of our friends to 3D print some of these.

yes, yeas and… yes!

you can easily lathe a slot for an E-clip (shaft collars and retainer clips work just as good)

The way the wheel and axle set up is laid out like this E-eclip W-wheel S-sprocket T-tubing B-bearing mount


I would recommend the center wheels be directly driven from the gearboxes.
Also I would suggest you may want to experiment with no tensioners and even eliminate the use of the bearing blocks on the outer wheels. It will reduce the machine time to fab the frame rails and eliminate the time used to fabricate at least 8 semi complicated parts. Simplifications like these help free up time that we have used to build a 2nd/practice robot. Good luck and keep up the CAD practice, it will really come in handy during build season.
mike d

E-clip slots would be made on a lathe

All shafts are keyed

There are two braces on the tube, on on the out side and one on the inside, and yes that is the only thing supporting the shaft.

If you or anyone else wants these CAD files I would be more than willing to send them to you. (seriously don’t be shy I would love some one to take a close look at this).