Reducing Colson Wheel Diameter
 

How would one go about reducing colson wheel diameter? This would be done so that a center drop would not be need to be made.

Re: Reducing Colson Wheel Diameter
 

It's funny you ask, all you need is a Lathe, File, and caliper!

http://i.imgur.com/i1vMoVE.jpg

http://i.imgur.com/UbcVnva.jpg

All you do it stick a piece of hex shaft into the lathe, slip a locking collar on, put the wheel in, turn the lathe on and hold a file to it.

We did this for ~100 wheels, they where turned from 3" to 2.9" and 2.7"

Re: Reducing Colson Wheel Diameter
 

Does the colson have a hex built into it? If so just take a 1/2 shaft with some sort of bolt/snap ring on the end. And just use a lathe to reduce the diameter.

Re: Reducing Colson Wheel Diameter
 

I'm not sure if you've had different results, but for us normal lathe tooling didn't work very well and found that a file worked the best.

Re: Reducing Colson Wheel Diameter
 

We used super small radius/sharp carbide insert that we normally use for aluminum. Works pretty well but I can see a file working pretty good as well or some misc HSS tool.

Re: Reducing Colson Wheel Diameter
 

If your wheels are spinning at the same RPM, wouldn't this cause issues with the actual contact speeds of the wheels being different? It seems to me that the larger center wheels would lose traction often and cause your drivetrain to "skip" or at least decrease the smoothness of the drive.

Re: Reducing Colson Wheel Diameter
 

I wonder if a file would add a tread pattern onto the colson, or if a better effect can be achieved with a knurling tool.

Re: Reducing Colson Wheel Diameter
 

I don't think a knurling tool will work in a soft material such as colson tread

Re: Reducing Colson Wheel Diameter
 

We worried about that in 2007, with an extra layer of tread affixed on the center wheels of our six-wheel-drive (it didn't have a drop on the axle). If anything, it made the robot drive more smoothly. We never decided exactly why that was.

Re: Reducing Colson Wheel Diameter
 

You need to use a very sharp tool to avoid just ripping up the wheel, but it can be done. For this case, I'd just use a file since you are taking off so little and you want to take off *just* enough for smooth turning but no more than you need to.

The very, very small diameter changes required to make this work would have a negligible effect on speed - seriously, this is taking about around 1/16th of an inch off the diameter of a wheel, maybe 1/8 if you're pushing it.

Re: Reducing Colson Wheel Diameter
 

I'll hazard a guess:

The larger wheels spin faster, and exert more traction force because they support more of the robot's weight. That means a slight drag at the smaller wheels, which will be toward the rear in a 6WD because the front smaller wheels are lifted by torque. Rear drag opposes turning, making the robot feel smoother to driver.

Re: Reducing Colson Wheel Diameter
 

Get that man some safety glasses! Not that I've never been guilty of doing the same thing in a hurry.

Re: Reducing Colson Wheel Diameter
 

Ok, thank you for the explanation.