paper: Belt Driven VersaChassis WCD - Step by Step guide

[lamk]

Thread created automatically to discuss a document in CD-Media.

Belt Driven VersaChassis WCD - Step by Step guide by lamk

[safiq10]

I am going to start this thread cause I can't believe this... We have been planning on making a WCD drive for the upcoming season but had no clue on how to do it. This just simplified and explained the proccess to us amazingly. Wow great job. If any other teams are planning on making a WCD drive and were stumped like us check this out might give you a few ideas on how to start.

[ryanh]

Very good job on this Ken. Thanks for letting me know about this paper. It was nice meeting you tonight.

[Mike Marandola]

Thanks. This is really useful. Does anyone have any experience using the 2 CIM ballshifters with the Versachassis?

[tr6scott]

Very Nice write up. Thanks for sharing.

[R.C.]

Originally Posted by Mike Marandola

Thanks. This is really useful. Does anyone have any experience using the 2 CIM ballshifters with the Versachassis?

You can do it if you make your own mounting hardware (adaptor plate similar to the 3 CIM ball shifter).

[AdamHeard]

Originally Posted by R.C.

You can do it if you make your own mounting hardware (adaptor plate similar to the 3 CIM ball shifter).

You can also just not put the 3rd cim in the 3 cim ones.

[thatprogrammer]

Thanks! My team already knew the basics of a WCD, but didn't know things like spacer sizes and other minor details. This has really made it easy to start making a WCD.


Question: Any reason you chose not to use a CNC to cut the holes for wheels at exact c-c distance?

[KamalRC]

Originally Posted by thatprogrammer

Question: Any reason you chose not to use a CNC to cut the holes for wheels at exact c-c distance?

They made it so that every team would have the resources to make it, not every team has access to a CNC. If your team has those resources, that would only help to make the process faster.

[thatprogrammer]

Originally Posted by KamalRC

They made it so that every team would have the resources to make it, not every team has access to a CNC. If your team has those resources, that would only help to make the process faster.

Sorry, I don't think I was very clear in my last post. I apologize for not communicating myself well.

My question was more along the lines of "why didn't you mention the possibility of using a CNC to make the c-c distance exact for teams that have access to one?" My question was there just in case a team had a CNC, but didn't really know that you could take advantage of c-c distance, and remove the need of a tensioner.

One again, apologies for not clearly asking my question.

[FrankJ]

Originally Posted by Mike Marandola

Thanks. This is really useful. Does anyone have any experience using the 2 CIM ballshifters with the Versachassis?

We use the 2 cim ball shifters. It was mounted on the top channel. It drives the center wheel with a 15mm belt. The outboard wheels are driven by the center wheel with 7mm belts.

[lamk]

Originally Posted by thatprogrammer

Sorry, I don't think I was very clear in my last post. I apologize for not communicating myself well.

My question was more along the lines of "why didn't you mention the possibility of using a CNC to make the c-c distance exact for teams that have access to one?" My question was there just in case a team had a CNC, but didn't really know that you could take advantage of c-c distance, and remove the need of a tensioner.

One again, apologies for not clearly asking my question.

The versablock is designed so that one can slides it up and down the frame tubing. One can position it to the desire C-C distance with or without CNC capability.
If one have the CNC capability one can mill a slot and use the vex bearing block (P/N 217-3436) for a more compact solution:


The question that begs for an answer is the necessity for a chain tensioner.
This year's kit chassis AM14U is belt driven and has no belt tensioner.
From what I read timing belt usually does not stretch and theoretically if you have the optimum C-C then you just set it and you're done. But what is the optimum C-C distance? Is it the distance that the WCP calculator spits out using the pulley size and belt size?? I felt that there is more to that. When I build the prototype the belt tension has a significant influence on binding and the ability to rapidly go backward and forward without slop. Too tight and things bind, too loose and there is slop.
Right now we are using the Cam belt tensioner to adjust the tension until we have a smooth drive train that is also responsive to rapid change in direction.
My guess is once I find the right tension than I can leave it alone but what is the best way to find the optimum C-C distance for the optimum belt tension without using a CAM tensioner. Does anybody have a good formula for the optimum C-C distance?

Ken Lam

[asid61]

Originally Posted by lamk

The versablock is designed so that one can slides it up and down the frame tubing. One can position it to the desire C-C distance with or without CNC capability.
If one have the CNC capability one can mill a slot and use the vex bearing block (P/N 217-3436) for a more compact solution:


The question that begs for an answer is the necessity for a chain tensioner.
This year's kit chassis AM14U is belt driven and has no belt tensioner.
From what I read timing belt usually does not stretch and theoretically if you have the optimum C-C then you just set it and you're done. But what is the optimum C-C distance? Is it the distance that the WCP calculator spits out using the pulley size and belt size?? I felt that there is more to that. When I build the prototype the belt tension has a significant influence on binding and the ability to rapidly go backward and forward without slop. Too tight and things bind, too loose and there is slop.
Right now we are using the Cam belt tensioner to adjust the tension until we have a smooth drive train that is also responsive to rapid change in direction.
My guess is once I find the right tension than I can leave it alone but what is the best way to find the optimum C-C distance for the optimum belt tension without using a CAM tensioner. Does anybody have a good formula for the optimum C-C distance?

Ken Lam

From what I've read, you should put in tensioners regardless because of the tolerances required for belt engagement. Adding a cam tensioner is less than 0.1lbs anyway, so there's no reason not to have one.

[Gregor]

This is an incredible resource, thank you for sharing.

[Oblarg]

Originally Posted by asid61

From what I've read, you should put in tensioners regardless because of the tolerances required for belt engagement. Adding a cam tensioner is less than 0.1lbs anyway, so there's no reason not to have one.

There is a reason not to have one, in that they cost money and can be safely skipped provided you have some other way of keeping the block from sliding.

The easiest way to do this is to simply assemble the thing without the cam, pull the versa-block until the belt is properly-tensioned, and then match-drill from one of the holes in the versa-block through the framing member and bolt it in place. You will then never have to worry about belt-tension again, and can save money on the cams. We did this last year at 449, and it worked perfectly. If your pulley is too close to the framing member to fit a nut on the other side of the versa-block, you can even tap one of the holes and just screw it into the versa-block itself.

I would not recommend doing this with chain.