Re: Simple 2-Speed 6WD for teams with few manufacturing resources
 

It doesn't work like that.
You need a CAD program as Madison said.
Try this thread: http://www.chiefdelphi.com/forums/sh...hlight=CAD+MAC

Re: Simple 2-Speed 6WD for teams with few manufacturing resources
 

Try ida-step. Its not fantastic, but it does let you view universal .stp CAD data on a mac.

Re: Simple 2-Speed 6WD for teams with few manufacturing resources
 

This may be of some interest.
http://www.andymark.com/product-p/am-0273.htm

Re: Simple 2-Speed 6WD for teams with few manufacturing resources
 

1114's KoS is essentially 6wd, 6in plactions, with toughboxes or Supershifters from AM. We used it in 2011 and loved the power it had over other robots. I feel like yours takes it to another level of steroids. It reminds me a lot of 2056's 2008 drivebase which I have been looking at a lot this off-season. http://www.2056.ca/photos.php?id=197...7440&offset=25

Are there any major differences in the supershifters over regular shifters?
Is there a reason for the double tensioners on the front chain run?
Any closer pics of the tensioner assembly?
Do you have an estimated speed?

Looks very clean simple! I love the simple mounting for the transmissions as that is my one peeve with COTS transmissions is getting them secured and still remain easy to work on!

Re: Simple 2-Speed 6WD for teams with few manufacturing resources
 

I may have done calculations wrong, but this thing looks like it's gonna go REALLY fast, like 22 fps. Is it supposed to be like that, or did I do my calcs wrong? (Most likely got those wrong, but I did it twice and got the same answer)

Re: Simple 2-Speed 6WD for teams with few manufacturing resources
 

What are you calculating the ratio with (What reductions in each stage, and what motor free speed, and speed loss constant?)

I get 3.86 and 9.86 ft/sec with no speed loss and 5310 CIM free speed, for reference.

The stages of reduction are:
12:40 CIM->cluster shaft
15:48 OR 28:35 cluster shaft->shift shaft
16:36 chain

It seems like a lot of chain reduction with 4" wheels. The ratio chosen seems to be perfect for 6" wheels (5.79 and 14.83 ft/sec with no speed loss, 4.69 and 12.01 with speed loss, 46 amp wall-push in low gear)

Re: Simple 2-Speed 6WD for teams with few manufacturing resources
 

Well that seems kinda low. My 22 fps is definitely wrong, and I've unfortunately lost the paper I used to calculate it (off to clean my room now!).

Madison, is Apalrd right? This looks like one of the best kitbots I've seen, but 10 fps and 3 fps are not my cup of tea. :|

Re: Simple 2-Speed 6WD for teams with few manufacturing resources
 

Madison won't cater to what speed each person prefers. The speed is up to you with your reductions.

I prefer the speeds Madison has this at.

Re: Simple 2-Speed 6WD for teams with few manufacturing resources
 

I am clueless with calculating speed, so can anyone tell me how to calculate speeds from gearbox reductions and the motors and things? :confused:

Re: Simple 2-Speed 6WD for teams with few manufacturing resources
 

3 FPS is definitely too slow. It's well below traction limited.

Re: Simple 2-Speed 6WD for teams with few manufacturing resources
 

http://ewcp.org/calculators/gearbox/single/ Might help you see what effect different reductions have on your output speed.

Re: Simple 2-Speed 6WD for teams with few manufacturing resources
 

Thanks!

Re: Simple 2-Speed 6WD for teams with few manufacturing resources
 

Great design! But I have 1 question.....in your bill of materials, why is there only 1 of the 2 kinds of spacers (1.25 and 2.5)? I count 8 1.25 and 4 2.5?
Thanks for posting!
EDIT: NVM silly me thought McMaster would sell 1 spacer for 8 dollars :D

Re: Simple 2-Speed 6WD for teams with few manufacturing resources
 

Thanks for pointing that out! I didn't know it existed at all.

The SuperShifters have a third stage of gear reduction inside that makes them better suited for directly driving wheels. They share many common parts.

The double tensioner was mostly to get the chain away from the floor and offer ground clearance. You could probably use just one in many cases.

See below for speed.

He is right.

Alternatively, you could use the AM Shifter with a 4:1 spread between high and low. This puts it into the 11.7 ft/s and 4.6 ft/s range. That might be more in line with current sensibilities about drive speeds.

It might also be possible to use a 22 tooth sprocket on the Shifter output instead of a 16, but I'm not sure if that'd cause any interference issues. You can't go any smaller than 36 tooth on the wheels, really, because the chain will interfere with the spacers. That maybe isn't as much of a concern with the VexPro wheels as it is with the AM Plaction wheels.

Remember, the intent here is to provide a simple, robust platform for teams to use or reference. Frequently, beggars can't be choosers and so, by minimizing manufacturing complexity, you limit available choices for things like drive ratios.

I believe they're sold in packages of ten.

Re: Simple 2-Speed 6WD for teams with few manufacturing resources
 

That's more my style. :) I like where this is going. By using some final staged gearing, from output shaft to wheel sprocket, do you think a speed of maybe 13 to 14 fps is achievable?

I love your simple, robust platform! It made up for not having a game hint released today. 488 never ceases to amaze me with their creations, and I can't wait to see what you come up with this season! Thanks a bunch! :D