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Old 02-11-2008, 07:57 PM   #1
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Ive been looking for detailed info about using tire truers, but have not found much. Anyone know of a good thread for this.
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Old 02-11-2008, 08:56 PM   #2
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Check this out from Xtreme
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Old 02-13-2008, 08:59 PM   #3
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My camera is charged, so I'm off to get some pics and do a quick tire truer tutorial... I'll be taking photos of my Hudy truer for this, but since most truers are somewhat similar in design and operation I think it will be useful to owners of other brands of truers as well... Watch this space in the next day or so for it.

The article in Xtreme was pretty informative as far as different things to do to the the tires themselves, I'm looking to focus more on the truer itself and get it set up properly and how to best use it... there are some small details that make a difference that nobody seems to mention in the manuals...
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Old 02-13-2008, 11:53 PM   #4
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Okay, here's the quick and dirty truer thing... I'd have had this done sooner but I fell asleep and only woke up a little while ago...

The pics and words apply to Hudy truers, but other truers I've seen (Ofna, Integy, etc.) are all similar enough in principle that it should apply to them as well. Not all of the adjustments may be present on some brands/models of truer, or they may be located in different spots than pictured here.

One word of warning... A tire truer can be a dangerous tool. Always exercise extreme caution around power tools, and be sure to unplug or disconnect from any power source before making adjustments or getting your hands/fingers near any sharp or rotating parts. Wear eye protection when working with a truer, and remove any rings, jewelry or loose clothing items before proceeding. Better safe than sorry.
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Old 02-14-2008, 12:00 AM   #5
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Here's the first pic... this illustrates some of the parts we'll need to deal with during the initial setup of the truer.



I wish I had a buck for every time I've seen someone at the track truing rear tires without removing the front wheel sleeve from their arbor knob... I don't know if everyone's 1/12 scale arbors have that little black sleeve, but most Hudys have it. It's there for the front wheels only... remove it and put it in a safe place when you're working with rear wheels. Here it is:



Place a wheel in your truer tighten the arbor and locate the taper adjustment. Here it is on a Hudy:



Some truers have a knob for this adjustment, on a Hudy you'll get it with an allen wrench.

Take a light pass with the truer, then remove the wheel and see if the truer cut straight across or made a tapered cut. If it's too close to tell by eye, roll the tire on a flat surface and see if it goes straight ir turns. If it turns, it's tapered. Adjust the taper adjustment until you can take a cut and the truer is cutting without a taper. Once that's good, we're ready to calibrate the depth scale.
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true tires-hudy001.jpg   true tires-hudy003.jpg   true tires-hudy004.jpg  
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Old 02-14-2008, 12:12 AM   #6
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I guess this would be a good time to mention backlash... I've never seen this covered in any instruction manual, so here it is:

When you set the taper adjustment, turning the knob or adjustment screw one way pulls the slide/carriage toward you, turning it the other way pushes the slide/carriage away from you. Always set this adjustment turning the screw to push the slide away from you (toward the tire). If you have to bring the carriage toward you, go a half turn or so beyond what you think you need, then push the carriage back away that half turn to finalize the setting. There is always going to be a tiny bit of slop in these adjusters, so by making the adjustment in the push direction we're not leaving any slop for the roating tire to be able to push the carriage back toward us.

The same applies to making a depth adjustment when taking a cut... Say you've just cut a set of fronts to 42mm, and now you need to cut a set of rears to 44mm. Don't just turn the depth knob to 44, bring it out to 45 or so, then go back in to 44 with the knob.

If you're a machinist, this is basic "yeah duh" stuff, but I'm not a machinist and I didn't figure it out for a while...
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Old 02-14-2008, 12:41 AM   #7
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Okay, now we've got the truer cutting straight, now it's time to get the depth scale to match the actual cut size.

Here's a pic:



The numbers on the scale represent tire diameter in millimeters. Every mark between the numbered mark represents 2 millimeters of diameter. The number on the knob get subtracted from the number on the scale to get the reading. In the picture above, you look first at the scale. Since the indicator line is between the 48mm and 50mm marks, we read the HIGHER number on the scale, then look at the knob... Each mark on the knob represents a tenth of a millimeter in diameter. The knob is right on the 1.3 mark in the picture, so we subtract 1.3mm from 50mm, to get a reading of 48.7mm. In a perfect world, a tire cut with the machine set like this would come off the machine at exactly 48.70mm diameter. Your machine might come out of the box perfect, I've yet to see it happen.

Here's how to calibrate that scale and knob so the number you see is the result you'll get. Grab your calipers and a big oversized new tire. I like to do the calibration close the the depth I'll be using most often. I run 1/12 scale, and I start a new set of tires at 44.5mm in back and 42mm up front. I do the calibration on my lathe at 43mm so it's right near where I'm working most often. If you're a touring car racer, you might be better off doing the calibration at 56mm or so (most of the TC guys I know are cutting their tires somewhere between 55 and 57mm or so) In a perfect world, you'd be able to do the calibration anywhere on the scale and have it hold true across the full range, but it doesn't always work out that way.

I don't want to cut a brand new rear to 43mm, so I'll do the calibration with a front tire. You touring car guys don't have to worry about this. Make sure the front wheel sleeve is in the arbor knob, and mount the front wheel in the truer and lock it down. Make sure the cutting bit is tightened securely in its holder. We don't want it to move after we do the calibration.

Parma 1/12 front tires come out of the box somewhere around 48mm. I don't want to take 5mm off in one pass, so the first cut I'll make I set the machine to 46mm. My habit is to not take off more than 2mm per pass, but I developed that habit using an autmatic truer with powerfeed. If your truer uses a feed knob to move the cutter across the tire (or if you can adjust the speed of your powerfeed) you can probably take bigger cuts, just move the cutter a lot more slowly for those big cuts.

With the depth set for a 46mm cut (the scale right at the 46mm mark, the knob on the zero mark) I'll make a pass. Take the tire out of the machine and measure it with the caliper. If your tire is right at 46mm, run right out and buy two lotto tickets. Everyone else will have to adjust the depth scale, the depth knob, or both. If your tire came off the machine at 48.0, or 44.0mm, all you need to do is loosen the two screws marked "depth scale adjustment" in the above picture. Loosen those screws, move the scale so the indicator mark lines up right on the "46" or "44" mark on the scale (if the tire measured 45.0mm), then snug the screws back down. They may need some fine tuning later. Everyone else will have to adjust the depth knob as well.
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Old 02-14-2008, 12:44 AM   #8
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More to come... gotta get some rest for now...
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Old 02-14-2008, 12:58 AM   #9
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Nice work. Thanks for puttin in the time.
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Old 02-14-2008, 03:58 AM   #10
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Don't mention it... I can talk about r/c/ cars till your ears bleed if I'm not careful...

Okay, the truer is cutting straight, the depth scale is set pretty close, now we'll get the depth knob dialed in (except you lucky lotto winners.)

In the last segment, we took the tire out of the machine and measured the actual size of the cut. The truer was set for 46mm. The actual size of the tire is most likely off somewhat. For the sake of this example, let's say the actual measured size of the tire after the test pass is 46.3mm. you'll notice a set screw in the depth knob. Loosen that set screw, and see if the knob pulls off easily. I've had some truers where it popped right off, I've also seen some where it didn't want to move. You want to get the knob off without turning the depth feed screw if you can. Also keep an eye out for a plastic washer that might come off with the knob. You don't want to lose that.

If the knob came right off with no hassle, then you'll just want to put it back on the shaft, only now instead of having the zero mark on the knob lined up with the little line, you'll want the "1.7" mark lined up there. The scale should be between 46 and 48mm, but closer to 46mm, with the knob at 1.7, the machine is set for 48mm - 1.7mm (46.3, just what we measured.)

Snug the setscrew in the knob down (we might have to readjust, so only snug it up at this point), and turn the knob to the zero mark. The 46mm mark on the scale should be in line with the indicator on the scale. Put the tire back on the arbor and do another test pass. When you take it out and measure it, it should be right at 46.0mm. If it's off by a hundredth or so, say 46.01 or 46.02 I wouldn't worry about it. Anything within a few hundredths of a mm is plenty close for me.

Check that the depth feed doesn't now have any in and out play to it. On the Hudy truers there's a plastic washer on each side of the post that the depth feed screw passes through. You want the post to be pinched between those washers enough that there's no real slop there, but not so tight that you're creating a bunch of friction in the knob. If everything looks good, go ahead and turn the depth right down to very close to the size you'll be using most often. Since I start my 1/12 tires at 44.5mm in back and 42mm up front, I do the final test pass at 43mm (scale between "42" and "44" marks, knob at "1".) Make a test pass, measure and you should be right on the money (or within a hundredth or two.) If so you're pretty much done. If not, you'll probably have to make a small adjustment to the knob.

Here's a pic of my truer set at 44.5mm (scale between 44 and 46, closer to 44 here, and knob at "1.5":




Here's the tire fresh out of the truer:



That's definitely good enough for me. It may seem like this is a lot to go through, but I find that it's a LOT easier on race day to true up a set of tires or two when I can just dial in the size and not have to stop and measure a lot during the process. It's also a lot harder to lose or misplace your caliper when you can leave it in the pitbox instead of taking it to the tire truing station.

I haven't really gotten into the tires themselves, I think the article in Extreme that FOXY923 mentioned does a good job covering that. I pretty much just cut tires to size and round the corners a bit. I haven't messed around with tapers or square edges versus round edges, so I can't offer any advice in that regard.

One last thing... If you can get an optional carbide cutter for your truer I think it's a good investment. The blades that come standard with most truers wear pretty quickly, you can go through this whole procedure and find the truer starts cutting bigger and bigger after what seems like a very short time.
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Last edited by Trips; 05-21-2010 at 01:47 AM.
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Old 02-14-2008, 04:25 AM   #11
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Just went back and edited some typos, so that about wraps it up... Hope it's helpful in some way.
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Old 02-15-2008, 05:17 PM   #12
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Very nice !
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Old 06-02-2010, 12:13 PM   #13
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Cool AWESOME!

I've got to bump this How To back into the limelight. Extremely helpful, thank you!
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