Wheels Wobble on Mandrel

[1reason]

This year I ran into a new issue. All my wheels are wobbling on the mandrel when I try to sand etc..

I bought another mandrel and tried many different wheels and the same. I'm embarrassed (but desperate) to ask what could cause that?

Have the new wheels changed since last year?

Any suggestions on an alternative solution?

 

[GravityX]

If time permits, purchase some lathe cut wheels to avoid this problem.

Many potential issues to the mandrel problem and one may not even be the mandrels fault, but a bad chuck on the drill motor could be the fault.

 

[pony express]

You have come across one of the keys to wheels. Keeping everything straight-level. The hubs need to be flat and level- or at least symmetric. What you're seeing is a poorly made mandrel or like Gravity said a bad chuck. A hand drill is not the perfect chuck for precision work on these areas. A good drill press chuck helps, but you still need to have the wheel rotate without wobble if you're going to sand the wheel. John's wheels are perfectly concentric so nothing needs to be done. I've tried sanding them lighly with mixed results. I've gone back to letting John do the precision work and then using a foam polishing bob to polish the wheel's critical surfaces. The polishing bob I use is one of those Mother's sells for the auto wheels shaped like a cone. The cone conforms to John's surface and only polishes the surface. I've tried the light sanding and its easy to screw the wheel up even with 2500 grit.

 

[1reason]

If time permits, purchase some lathe cut wheels to avoid this problem.

Many potential issues to the mandrel problem and one may not even be the mandrels fault, but a bad chuck on the drill motor could be the fault.

No time for this year, but for next year....

Still, it seems strange that only the wheels wobble and the mandrel appears to rotate straight (maybe time for new glasses)

 

[1reason]

You have come across one of the keys to wheels. Keeping everything straight-level. The hubs need to be flat and level- or at least symmetric. What you're seeing is a poorly made mandrel or like Gravity said a bad chuck. A hand drill is not the perfect chuck for precision work on these areas. A good drill press chuck helps, but you still need to have the wheel rotate without wobble if you're going to sand the wheel. John's wheels are perfectly concentric so nothing needs to be done. I've tried sanding them lighly with mixed results. I've gone back to letting John do the precision work and then using a foam polishing bob to polish the wheel's critical surfaces. The polishing bob I use is one of those Mother's sells for the auto wheels shaped like a cone. The cone conforms to John's surface and only polishes the surface. I've tried the light sanding and its easy to screw the wheel up even with 2500 grit.

I've ruined more than my fair share of wheels with sandpaper, but at least I'm improving. I will try it in the drill press and see if the same problem is there. maybe just my hand drill

 

[Guest]

It may be that you are not centering the wheel on the mandrel.

before you snug down the screw you want the wheel to kind of "find" the middle.

Don't just screw it on and assume. if you keep it a little loose until the last turn or so, and hold the mandrel so the wheel will balance you should be able to get it on there fairly straight.

Not sure if this is it. Just tossing it out there.

 

[Kinser Racing]

No offence intended here but STOP using the derby worx junk. I'd be totally surprised if that stuff makes you faster then out of the box stuff. Your other thread said you flattened the axles. The stuff really is junk, designed to make them money and nothing more. Purchase stuff designed to make you faster @ DerbyDad4Hire.com /images/boards/smilies/smile.gif

 

[1reason]

It may be that you are not centering the wheel on the mandrel.

before you snug down the screw you want the wheel to kind of "find" the middle.

Don't just screw it on and assume. if you keep it a little loose until the last turn or so, and hold the mandrel so the wheel will balance you should be able to get it on there fairly straight.

Not sure if this is it. Just tossing it out there.

Thanks, I will try that. I didn't have this issue until this year.

 

[1reason]

No offence intended here but STOP using the derby worx junk. I'd be totally surprised if that stuff makes you faster then out of the box stuff. Your other thread said you flattened the axles. The stuff really is junk, designed to make them money and nothing more. Purchase stuff designed to make you faster @ DerbyDad4Hire.com /images/boards/smilies/smile.gif

No offense taken and I appreciate any and all help. I'm going to order the silver bullet and other stuff so I will follow your advice also.

 

[Kinser Racing]

No offence intended here but STOP using the derby worx junk. I'd be totally surprised if that stuff makes you faster then out of the box stuff. Your other thread said you flattened the axles. The stuff really is junk, designed to make them money and nothing more. Purchase stuff designed to make you faster @ DerbyDad4Hire.com /images/boards/smilies/smile.gif

No offense taken and I appreciate any and all help. I'm going to order the silver bullet and other stuff so I will follow your advice also.

A lot of people have learned the hard way including Derby Dad, so don't be ashamed. /images/boards/smilies/thumb.gif

 

[1reason]

No offence intended here but STOP using the derby worx junk. I'd be totally surprised if that stuff makes you faster then out of the box stuff. Your other thread said you flattened the axles. The stuff really is junk, designed to make them money and nothing more. Purchase stuff designed to make you faster @ DerbyDad4Hire.com /images/boards/smilies/smile.gif

No offense taken and I appreciate any and all help. I'm going to order the silver bullet and other stuff so I will follow your advice also.

A lot of people have learned the hard way including Derby Dad, so don't be ashamed. /images/boards/smilies/thumb.gif

Ha, learning the hard way is SOP for me. Life would be so much easier if it wasn't true, but I fear less interesting.

Have a great weekend!

 

[Guest]

As usual Kinser is right on the mark. Don't wait until last minute though. Keep the derby fresh in the boy's mind, and yours as well. Get the stuff now so next year you know how it works.

 

[DerbyDad4Hire]

By the wheels I am working with now try and find #2 or #3's. They will be better out of the box than trying to do them yourself with that setup. The only thing that is good for is lightning the wheel up but you are getting it more out of round.

 

[1reason]

Thanks for all your answers.

I'm not really sure what the problem is. My high quality drill press (HF $89) and hand drill both are displaying the same wobble. BUT this is the fourth year and clearly the worst, not sure why.

I use power tools more in the one week of building PWD car(s) than the other 51 week combined. Maybe that has something to do with it...

 

[EggHead Racing]

I stopped using a Mandrel on my tires because of the scratches that I'd get inside my hubs. I just use a qtip shaft inside the hub to lightly polish and sand wheels.

 

[chromegsx]

It could just be the wheel is that bad. You didn't say how much wobble. Some runout is just obvious, but once it gets down to a certain point you need to place a stationary object next to the wheel to see how much the gap between the object and wheel fluctuate. do the same thing with your mandrel or a pin gage in the chuck and see how far they are off. If its the same between pin gage/mandrel and a wheel, it likely your wheel isn't "that" bad. but only way to know for sure is to mount wheel on a pin in the chuck and have a dial indicator to measure as you spin wheel on pin. There are about as many ideas on how to mount and measure runout on wheels as there are ways to skin a cat, but the best methods are best explained by machinsts with lathes (that's not me). It doesn't sound like that is an option for you, so that is why I offer a slight lesser elegant solution to check them. As others said even if you do get it close, there still may be runout in the chuck or drill spindle itself although not likely to be enough to call it "wobble". hand drills are worse than drill presses which are worse than lathes...on the average. I only mention this as you indicated you like to learn the hardway. /images/boards/smilies/wink.gif I like to think I'm forced to learn the hard way, via lack of funding for the "right" tools.