Has anyone experimented with VexPro 3 CIM Dog Shifter on the KOP? I’m aware that VexPro has a guide to installing the ball shifter on the kit of parts chassis, but nothing regarding interfacing the 3 CIM Dog Shifter. Interested to hear how people dealt with the different mounting holes on the gearbox and KOP plate and any other concerns with using this gearbox on the KOP chassis.
Here’s the power point I plan to use tomorrow for the presentation (literally - I’m going to download from this post to do the presentation). I also have a bunch of hands-on pieces parts, including a KoP chassis robot that I mostly assembled yesterday by myself. I had already cut the chassis frame members, but the square deal parts and the belts were delivered at 11:30 yesterday, and I was driving it at 2100 (9pm), using AndyMark’s Quick and Dirty control system. My goal with this was simple - to make the smallest robot I could from the KoP chassis that included an FRC-legal battery stowed inside the chassis similar to the 14U battery tray. This robot is 15.3" long and 16" wide (before “minor protrusions”). I expect that I’ll do an update afterward, with photos and notes from the workshop.
OBTW - the original powerpoint brief includes speaker notes on some slides. I’ll figure out how to add them someday soon.
Bayou-Workshop-2018-KoP-Chassis.pdf (297 KB)
This is exactly how we’ve done it for many years.
This is great, Gus. Thanks for putting it together and making it available.
Have you been able to replace the motors by accessing the mounting screws through the holes in the outer plate? Would the 10-32’s drop into the gearbox?
When you print the PowerPoint slides, the print dialog box will open. In PowerPoint 2007, there is a menu box in lower left quadrant that says “Print what:” with a default of “slides”. Select “Notes Pages” in that menu then print.
If you are doing a “Save As”, select “pdf”. This opens the “Options” dialog box. Under “Publish what” on the left side, select “Notes pages” then “OK”.
With 4" wheels, no; you’d have to go through the tread. It looks like 6" or 8" hi-grips should work; I’ll try a test of this in coming days. Yes, an 8" 2010 wheel has plenty of clearance, and AM’s drawings show even more space on the 6" and 8" hi-grips. Note that you need a 5/32" allen wrench about 5" long to reach all the way through; this is definitely longer than many. The only one I have which reaches is the Eklind 51610 which I purchased at the local Ace Hardware, but is also available from MSC and others.[/edit] If you turn the gearbox sideways so the CIMs extend upward, it is possible to remove the CIM screws and lower them through the access holes in the shaft plate, then re-insert them the same way. (In both cases, put one screw in/out halfway, do the other, and finish up the first.)
Thanks, this is what I was planning to do.
Also, the demo robot I brought. with my size 10-1/2 foot for scale. The versaframe channels are there as a “stub” to show how to attach VF to the chassis. Also made a good example for Curtis’ bumper and inspection talk. I also discovered that Home Depo’s piano hinge is highly compatible with the kit chassis and versaframe. OBTW, I’m considering making this into a gear runner, and at least mocking up a legal control system as an exercise in the art of the possible. I’ll likely switch to a bottom-access battery as I add stuff on top.
Note - in order to fit the CIM at the far left, I had to trim a bit from the outer sheet at that end. I trimmed all the way back to the outer row of holes, but I could have removed much less and have the motor fit, but I figured with a 9" span, I could make do with less material.
Not also that if you made this a bit wider (1.5"?), you could do a 4 mini-CIM drive.
I have attached the brief as notes pages with a few updates.
Bayou-Workshop-2018-KoP-Chassis-post.pdf (2.01 MB)
Sorry for reviving, but I was wondering, what benefit did the tube axle have over the 3/8 inch bolts that are normally used, and do you have pictures of this setup? Also, how did you ensure that the panel nuts were aligned properly before you riveted?
The benefit is that you don’t have to try to align spacers - they already sit on the tube axle (or if you are really fancy, do away with spacers completely and cut circlip grooves in the tube axle). You still have to fight a little against belt tension, but it makes the job of wheel swaps slightly less painful.
The panel nuts actually have a bit of float in them, so it isn’t super critical. But alignment is pretty easy: just install a short bolt through the inner plate, into the nut first, before riveting.
That’s super neat! Did you use 9/64 rivets, or did you drill the holes out for something larger?
Drilled out for 1/8 steel rivets.
We’ve also used these which have the self alignment and big tabs for drilling. https://www.mcmaster.com/90955a129
What do they mean when they say the threads “float” inside the housing?
It’s two pieces. The inner piece is threaded, and can float a bit (but not rotate) in the outer piece
Oh I see. Thank you! Do you have any other modifications you found worked well on the kitbot, or any good general practices when working with it?
Do you have some photos showing the spacers on the tube axles and where the panel nuts are installed? Did you use anything to keep the spacers on the tube axles?
No photos sadly. We used shaft collars actually, but the wheels slid around on us. You could use anything to hold spacers on, even a bit of hot glue.
Oh, that was what I was thinking about doing, since we don’t have a lathe. Do you think using thunderhex instead of round tube might work better?
We swapped the 4" DuraOmnis onto the corners of our 2015 bot and left the traction wheels in the center. It still has the center drop, but overall those made low speed turning so much smoother, especially when it was carrying a full stack.
The hole in thunder hex fits a #10 bolt. I think that’s a little thin for the job of supporting the wheel (although you might get away with it).
Vex’s 1/2" round tube axle stock has a hole for a quarter inch bolt, which would be stronger. https://www.vexrobotics.com/shaft-stock.html
Would the shaft collars stay in place on the tube stock? Also, I was thinking about boring it out to 3/8, to fit the holes already on the kitbot.