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  #1  
Old 01-22-2010, 03:02 PM
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Ryma10 Ryma10 is offline
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Default Tire truing machines or methods

What are some of the methods used for truing tires other than purchasing a pricey truing machine? Are there old school tricks or homemade machines guys and gals are using?
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  #2  
Old 01-22-2010, 03:23 PM
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For me the basic methods are:

1) turn the car in the reverse direction on the track and slide some sandpaper under it.
Then hold the car lightly on the paper while running up the power with the controller.
Three hands sometimes helps

2) If you have alloy wheels I have used a largish electric drill held horizontally in a bench vice with a suitably size axle locked in the chuck. Then fit your hub/tyre,to be trued,to the axle.
Use sandpaper glued to a flat block to hold against the tire.

3) Use a dedicated tire truing machine...I prefer the hudy.


or this....


I saw this at a race meet.The owner told me the big brass bars were handles!!!

regards
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  #3  
Old 01-22-2010, 03:34 PM
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i built my own tire truing machine as well as a sanding station. they both work great:

tire truer:
http://www.slotcarillustrated.com/po...ad.php?t=34305

sanding station:
http://www.slotcarillustrated.com/po...ad.php?t=36128
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  #4  
Old 01-22-2010, 04:43 PM
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boopiejones very cool tire truing machine. Thanks for the info and pics.
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  #5  
Old 01-22-2010, 05:45 PM
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I like the tire truing chassis with handle.

My old school technique revving my car on a drywall spatula covered with a 50 and/or 200 grit sandpaper taped to either side with the car pointed the wrong way on a power base:





Eventually I bought a pricey truing machine: the RSMII from Germany.







It allows me to mount a stock rear axle assembly and true it. I have yet to find an assembly that is actually round. Works great for most rubber and urethane tires. Not so much on silicone tires .
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  #6  
Old 01-22-2010, 07:01 PM
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This has trued silicones for me:



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  #7  
Old 01-22-2010, 07:27 PM
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Default Nice looking wheels there RL

Yeah, I've been using a similar setup to Robert's recently - basically a Slot.it inline pod with a motor glued into it and crown gear set up so that it can't move laterally along the axle. That way, you can just attach your glued wheel/tire set onto the axle and sand away. I use a 9v power source from some Chinese rechargeable device that don't work no more to spin the motor.

I'm too cheap to buy a Hudy, and besides that, I can't afford to take six weeks off work to get the job done with it, like those guys in New Hampshire and Connecticut.

But I can afford to buy a selection of 60~1600 grit sandpaper from the hardware and model shop stores ...
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  #8  
Old 01-22-2010, 07:27 PM
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Robert,

Are you getting your downward pressure just via the weight of the assembly and gravity? Also, what grit paper do you use to sand the Silly's? Do you sand them wet or dry?

Thanks,

David

Quote:
Originally Posted by Robert Livingston View Post
This has trued silicones for me:


Last edited by pukplyr; 01-22-2010 at 09:57 PM.
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  #9  
Old 01-22-2010, 08:28 PM
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IF you have perfect wheels and you buy new Slot Car COrner wheels about the only thing you need to do is to profile the sides some AND IF you do get any tire chatter put soem Parfix 3410/3416 Adhesive betwen the tires and wheels...No more tire chatter. Remember that IF you are serious about balance set your crown gear setscrew and tire setscrews all equal distance (120 degrees) apart. Line them all up nice and pretty and you will get some out of balance issues that can be noticed at top end...

Last edited by lindseyangell; 01-22-2010 at 10:12 PM.
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  #10  
Old 01-22-2010, 09:08 PM
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It looks like Mr. Livingston uses the brass screws located behind the axle to apply downward pressure to true the tires.
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  #11  
Old 01-22-2010, 09:11 PM
chouinam chouinam is offline
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I've noticed a lot of racers true their tires running them in reverse. Is there a speacial reason for this? Or is it just a personal preference?

Marc
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  #12  
Old 01-22-2010, 09:16 PM
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running in reverse seems easier to hold the car. especially if you are doing it one handed.
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  #13  
Old 01-23-2010, 05:27 AM
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My tire truer has four screws that pull down on the pod, and a fulcrum under the motor (the length of HO brass rail). The chassis actually bends at the fulcrum, and behind the motor, because the screws are tight. I tighten the two screws at the tail of the pod about 1/8 turn at a time, to pull the tires down onto the sand paper. For rubber tires, the process goes fast, but for Super Tires sillies , it takes much longer, and I have to cool the tire with water dripped onto it as I go. Thus, I use wet or dry sandpaper.

I tighten down the rear screws until the tires' high spots just touch the paper. I let it skip along for 10 minutes or so, adding water, then I give it a 1/8 turn down, then about 10 more minutes, etc. until the high spots are all gone and the whole tread is flat. It is tedious and I only bother truing Super Tires for cars that will go into proxy races.

About one in four Super Tires gets discarded around here, due to out of round. The rest are nearly, but not quite concentric out of the box. The best ones are glued to their rims, then sanded to perfection, or as near as I can get.

I typically run the sander at about 4 to 6 volts, with 3.1:1 reduction, and a 19k/12v motor. Sanding (tire) speed is less than 3,000 RPM. I don't think the imbalance caused by set screws is a problem, especially since the axle is held firmly in place.

Direction of rotation is forward, if the motor pod was in a car.

Grit is 220; Norton wet-or-dry from the automotive store. I put a final finish on the tires by running hundreds of laps on the wood track. Incidentally, I believe a rougher grit like 220 provides cooler and faster cutting than a finer grit, as less pressure is needed. The use of 1600 (or any very fine grit) does not seem necessary, as all sanding marks disappear as the tire runs laps. Since the tire does finish itself by running, it is clear that the tire does indeed wear, and does deposit particles of silicone on the track. This would explain the visible, black "groove" laid down by sillies , and would explain why Ortmann and rubber tires pick up a glaze that destroys their grip.

Last edited by Robert Livingston; 01-23-2010 at 07:55 AM.
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  #14  
Old 01-23-2010, 03:14 PM
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Robert,

Thanks for the additional information! Sounds like yet another great application for that elusive material known as "Patience"!

David
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  #15  
Old 01-29-2010, 08:06 PM
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Geez, you guys are clever! Robert's and Boopie's setups are very, very smart.

My RSM II just arrived today, giving a great excuse to stop studying for a bit and check in with y'all.

Instruction sheet is in German!
:-O

Dr. V., do you use those brass bearings on every axle you're truing with the RSM II? And if another grit of sandpaper were to be used, I assume it'd be adhesive backed?

More things I hadn't thought of.
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