My implementation of Teeeman's Wheel Weight Wonder

Discussions on race planning, preparations and how to run a "fair" and fun race.
Post Reply
User avatar
Vitamin K
Master Pine Head
Master Pine Head
Posts: 980
Joined: Sat Apr 20, 2013 7:26 pm
Location: Montgomery County, MD
Contact:

My implementation of Teeeman's Wheel Weight Wonder

Post by Vitamin K » Thu Jan 01, 2015 7:22 pm

I built a copy of Teeeman's rig (with 3 Cub Dad's modifications) and made a video of its use.

I realized that I mounted the clamps in an inverted position that actually is less advantageous when you consider gravity and mounting the car. It works, but I think it would be easier to use if I changed the orientation, which I might do.

Anyhow, here's the video. Hope it is possibly useful.




ngyoung
Master Pine Head
Master Pine Head
Posts: 234
Joined: Thu Apr 03, 2014 6:36 pm
Location: Eyota, Minnesota

Re: My implementation of Teeeman's Wheel Weight Wonder

Post by ngyoung » Thu Jan 01, 2015 10:31 pm

So you're doing this for every car at inspection or just ones you have suspicion of being shaved lighter? I know some pull a wheel of the finalist cars to weigh before anouncing the winners. This looks like a good setup since a lot of building tip sources tell scouts to glue their axles in.



User avatar
Stan Pope
Pine Head Legend
Pine Head Legend
Posts: 6888
Joined: Sat Jul 05, 2003 7:01 pm
Location: Morton, Illinois
Contact:

Re: My implementation of Teeeman's Wheel Weight Wonder

Post by Stan Pope » Thu Jan 01, 2015 10:46 pm

Cool! Are you doing anything special to make the axle vertical? If not, how far off vertical does it work reliably?


Stan
"If it's not for the boys, it's for the birds!"

User avatar
Vitamin K
Master Pine Head
Master Pine Head
Posts: 980
Joined: Sat Apr 20, 2013 7:26 pm
Location: Montgomery County, MD
Contact:

Re: My implementation of Teeeman's Wheel Weight Wonder

Post by Vitamin K » Fri Jan 02, 2015 12:17 am

Our plan is to weigh a single rear wheel of every car that enters our Pack's derby. We wanted to be able to enforce a limit on lightened wheels, but didn't want to have to remove anything from any cars...especially if, as you mentioned, axles were glued in.
ngyoung wrote:So you're doing this for every car at inspection or just ones you have suspicion of being shaved lighter? I know some pull a wheel of the finalist cars to weigh before anouncing the winners. This looks like a good setup since a lot of building tip sources tell scouts to glue their axles in.



User avatar
Vitamin K
Master Pine Head
Master Pine Head
Posts: 980
Joined: Sat Apr 20, 2013 7:26 pm
Location: Montgomery County, MD
Contact:

Re: My implementation of Teeeman's Wheel Weight Wonder

Post by Vitamin K » Fri Jan 02, 2015 12:20 am

At this point, the only thing I'm doing is getting the car on its side, the bottom roughly 90 degrees to the ground. The car I tested in the video had a 3 degree canted rears, so those seemed to work fine.

It probably would be good to incorporate some kind of leveling mechanism for the base, so I could make sure that the surface the scale rests on is level. Not certain what can be done about the axle angles, though. I might try shimming the car at different degrees to see how far I can go before I get an off reading, though.
Stan Pope wrote:Cool! Are you doing anything special to make the axle vertical? If not, how far off vertical does it work reliably?



User avatar
Stan Pope
Pine Head Legend
Pine Head Legend
Posts: 6888
Joined: Sat Jul 05, 2003 7:01 pm
Location: Morton, Illinois
Contact:

Re: My implementation of Teeeman's Wheel Weight Wonder

Post by Stan Pope » Fri Jan 02, 2015 2:03 am

Insensitive to 3 degree camber ... sounds great! Wonder if less play in the axle-bore would hurt sensitivity?


Stan
"If it's not for the boys, it's for the birds!"

User avatar
Vitamin K
Master Pine Head
Master Pine Head
Posts: 980
Joined: Sat Apr 20, 2013 7:26 pm
Location: Montgomery County, MD
Contact:

Re: My implementation of Teeeman's Wheel Weight Wonder

Post by Vitamin K » Fri Jan 02, 2015 6:57 am

Excellent question. I guess I should obtain some .092" aftermarket axles and try those, since there's less play between the axle and the bore, there.
Stan Pope wrote:Insensitive to 3 degree camber ... sounds great! Wonder if less play in the axle-bore would hurt sensitivity?



User avatar
Stan Pope
Pine Head Legend
Pine Head Legend
Posts: 6888
Joined: Sat Jul 05, 2003 7:01 pm
Location: Morton, Illinois
Contact:

Re: My implementation of Teeeman's Wheel Weight Wonder

Post by Stan Pope » Fri Jan 02, 2015 10:38 am

That should cover "binding."

Since accuracy requires that none of the wheel weight is carried by the axle, anything that causes the wheel to be suspended by the axle will affect accuracy. That could also include viscosity of lubricant.

Can operating procedures include a step which detects such? For instance, if scale is raised until weight is registered (W1), then raised further until weight increases (W2), then lowered 1/2 way between those two points, does weight return to initial weight (W1)? If so, then I think that means that the wheel moves freely on the axle (no binding, no adhesion, etc) and that the weight (W1) is reliable.

Is the scale height adjustment tight (no play)? With some of the tight gap tolerances (1/32" down to 1/64"), you might need to add a dial indicator to the scale platform to show "lower 1/2 way" if the height adjustment is "sloppy."

Is there any other possible way that the axle could carry part of the wheel's weight?


Stan
"If it's not for the boys, it's for the birds!"

User avatar
Vitamin K
Master Pine Head
Master Pine Head
Posts: 980
Joined: Sat Apr 20, 2013 7:26 pm
Location: Montgomery County, MD
Contact:

Re: My implementation of Teeeman's Wheel Weight Wonder

Post by Vitamin K » Fri Jan 02, 2015 1:19 pm

Yeesh, Stan, why didn't you ask these questions on Teeeman's original post? Then he would have had to solve the problems, not me! :D

The dial indicator's a good idea, though, I think. Would also provide a degree of feedback to the user.

One saving grace: None of the factors that come into play should ever make a wheel appear to weigh less than it actually does. Therefore, once you get an idea of the margin of error, you at least get a sense of what you're measuring. So if your limit is 2.4 grams, maybe a 2.2 gram wheel might slip past? But a 1.8 or a 1.4 is another matter entirely.
Stan Pope wrote:That should cover "binding."

Since accuracy requires that none of the wheel weight is carried by the axle, anything that causes the wheel to be suspended by the axle will affect accuracy. That could also include viscosity of lubricant.

Can operating procedures include a step which detects such? For instance, if scale is raised until weight is registered (W1), then raised further until weight increases (W2), then lowered 1/2 way between those two points, does weight return to initial weight (W1)? If so, then I think that means that the wheel moves freely on the axle (no binding, no adhesion, etc) and that the weight (W1) is reliable.

Is the scale height adjustment tight (no play)? With some of the tight gap tolerances (1/32" down to 1/64"), you might need to add a dial indicator to the scale platform to show "lower 1/2 way" if the height adjustment is "sloppy."

Is there any other possible way that the axle could carry part of the wheel's weight?



User avatar
Stan Pope
Pine Head Legend
Pine Head Legend
Posts: 6888
Joined: Sat Jul 05, 2003 7:01 pm
Location: Morton, Illinois
Contact:

Re: My implementation of Teeeman's Wheel Weight Wonder

Post by Stan Pope » Fri Jan 02, 2015 3:11 pm

Vitamin K wrote:Yeesh, Stan, why didn't you ask these questions on Teeeman's original post? Then he would have had to solve the problems, not me! :D
Good question! Sometimes I have to mull over these ideas for a while (a year or three) before I see the consequences!


Stan
"If it's not for the boys, it's for the birds!"

Post Reply