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This is how you true tires...


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#1 Garry S

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Posted 11 January 2017 - 11:45 PM

I wasn't happy with the Hudy and always wanted a Unimat anyway. It's not as portable, but it works better and has a lot more uses!

 

unimat2.jpg

 

unimat1.jpg


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#2 MarkH

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Posted 12 January 2017 - 06:42 AM

When I had access to a surface grinder my tires were ground down to size. Dead flat and turned with a spin fixture. A couple of guys in our club do this same thing as you have set up.


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Mark Horne

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#3 Bill from NH

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Posted 12 January 2017 - 06:50 AM

Garry,

 

That looks like the model I've had since 1970. At one time, you could find Unimat tooling and accessories in the Sears tool catalog, but that was a few years ago. There is/was a Unimat users group on Yahoo, but I haven't been there in awhile.

 

Because it hasn't been imported in years, you'll probably find Unimat parts selling at high prices. Over the years, I'll repack the headstock bearings, but I've not had maintenance issues with mine.


Bill Fernald
 

How old should a highway be before you tell it, that it has been adopted?


#4 triggerman

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Posted 12 January 2017 - 07:21 AM

I use my MicroMark Mini Lathe with almost the same set-up to rough grind all of my 'recaps.' It saves wear and tear on my Hudy tire truer.

Maybe later today I'll post some photos of my process.


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#5 airhead

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Posted 12 January 2017 - 08:02 AM

How do you use a surface grinder to turn down wheels?
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#6 MSwiss

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Posted 12 January 2017 - 08:20 AM

You motorize something like the below, put your axle in the proper size collet, and while on/spinning, you feed it underneath the spinning grinding wheel.

Speaking of collets, the set-up in the first post would probably be more precise, using a collet to hold the axle, instead of the three (?) jaw chuck.

Also, hanging that much axle out of the chuck, unsupported on the other end, to cut two tires at once, is less than ideal,
with doing two 3/32" tires, of course, more iffy than two 1/8" tires.

5CSpinIndexFixturePinko.jpg


Mike Swiss
 
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#7 wbugenis

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Posted 12 January 2017 - 09:56 AM

Speaking of collets, the set-up in the first post would probably be more precise, using a collet to hold the axle, instead of the three (?) jaw chuck.

 
Using a three-jaw chuck will introduce several thousandths runout to whatever you are grinding.
 
My USA-made Hardinge collets are certified to only  0.0007" - good for tires, but not good enough for your commutators.
 
The Hudy, when new, will do better.  The V-blocks on the comm lathe will wear.


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William Bugenis

#8 MSwiss

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Posted 12 January 2017 - 09:58 AM

The device below is a better example of what you would use with a surface grinder.

A mere $1,800 plus the prices of 3/32" and 1/8" collets.

nj60-120-100.png


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Mike Swiss
 
IRRA® Components Committee Chairman
Five-time USRA National Champion (two G7, one G27, two G7 Senior)
Two-time G7 World Champion (1988, 1990)
Eight-time G7 King track single lap world record holder
17B West Ogden AveWestmont, IL 60559, ( 708) 203-8003
mikeswiss86@hotmail.com (also my PayPal address) 
Note: Send all USPS packages and mail to: 5858 Chase Ave., Downers Grove, IL 60516
Make checks out to Chicagoland Woodworking, Inc.


#9 wbugenis

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Posted 12 January 2017 - 10:34 AM

A little pricey for tires, but this is what you need to grind your armature stacks.
 
They do get out of round, especially on the open motors.
 
You still have to deal with collet runout.
William Bugenis

#10 Steve Deiters

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Posted 12 January 2017 - 10:42 AM

Interesting set-up. What speed do you run the tires and the grinder? 

I bought an Unimat on eBay expressly for this purpose.

#11 Garry S

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Posted 12 January 2017 - 12:58 PM

I'm running the lathe at its slowest speed and the grinder at its fastest. They still turn into each other (like the Hudy), so it's not ideal but does work fine. The grinder is canted about ½° clockwise to ensure an even cut. The axle extends 1.25" from the chuck, and runout at the far end is less than .001".
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#12 Steve Deiters

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Posted 12 January 2017 - 01:17 PM

Many thanks for the info.



#13 Bill from NH

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Posted 12 January 2017 - 01:24 PM

Unimat sold a special headstock arbor for collets and collets, too. Forty years ago, I didn't have the need to spend the extra money, but I could have used them many times since. Never having done so has always been my biggest Unimat regret.

Bill Fernald
 

How old should a highway be before you tell it, that it has been adopted?


#14 airhead

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Posted 12 January 2017 - 03:49 PM

​ This an old tire machine sold at slot car raceways in the '60s. I was told that Unimat made them.

IMG_2920.JPG

IMG_2921.JPG


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#15 MarkH

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Posted 12 January 2017 - 05:22 PM

The Pinko spin fixture shown above is what I used. I would square and center the fixture to the wheel, 5c collet with 1/8" pin ground down to 3/32".

 

Plenty close enough for slot car tires. The spin fixture also has a slop/stop/locking screw on the top. Just some light pressure and everything ran true.


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#16 hiline2

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Posted 12 January 2017 - 07:34 PM

From the past. Used one like this, it did very well trimming!

tirtetool.JPG
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#17 Garry S

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Posted 12 January 2017 - 09:19 PM

I've seen that ad for the Modelmat hundreds of times, but often wondered if any were actually produced. Now I've seen a real one!
 
This also makes me wonder if I really need the grinder, and might be better off with just a strip of sandpaper like that machine uses. I think I'll give it a try.
Garry Stoner

#18 Mach9

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Posted 12 January 2017 - 09:54 PM

I trimmed/sized hundreds of tires (50 cents a pair) at my raceway years ago on a Taig lathe using nothing but  a 1/4" shank boring tool and radiused them after truing with an ignition points file.

I let the lathe go when I sold the raceway, but first thing I did was order another one. A very versatile little machine. Turned hundreds of ink pens on it and numerous other tasks. Have turned comms on it, but just never sprang for the diamond bit.

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#19 Phil Hackett

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Posted 13 January 2017 - 12:36 AM

Then there's this. You're not going to take it to the track: it's 5,500 pounds (2,500 Kilos for our decimal friends....) and won't run on 12v power supply...
 

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#20 Steve Deiters

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Posted 13 January 2017 - 12:38 PM

I always had visions of that X-Acto blade breaking and right into your eye!



#21 Pete L.

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Posted 13 January 2017 - 07:00 PM

Here's my vintage tire cutter by Rual Engineering Co. Inc. out of California (excuse the fuzzy pic)... and yes, it uses a  #11 X-Acto blade as a cutting edge.

 

I always use eye protection when I trim tires!!!

 

CARS DEC 2013 001.jpg


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#22 Bill from NH

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Posted 13 January 2017 - 08:13 PM

Pete,

 

On your tire cutter, how to you set the X-Acto blade to cut different diameter tires? After being cut, do the tires require any sanding other than rounding the tire edges?

 

I've never seen either machine shown in this thread, but I think Rick Thigpen has one of the American Edelstaal units.


Bill Fernald
 

How old should a highway be before you tell it, that it has been adopted?


#23 triggerman

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Posted 16 January 2017 - 07:58 PM

Sorry for the delay in posting pictures of my set up for rough grinding the tires I use for calibrating Knob Jobs on Tire Truers. I usually make a batch of a dozen pairs or more and store them in the freezer until needed. The donuts are Alpha Supernaturals and grind fairly easily.
The Dremel Sanding drum is mounted in a flex shaft which is held in a quick change tool holder. The orange object in the background is an attachment for a shop vacuum.
I'm having issues using my Photobucket account so I posted a quick video on YouTube.

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#24 anumber1

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Posted 25 January 2017 - 03:45 PM

Regarding the setup that started this thread:
 
What do you do about the runout in the moto-tool? My Dremel and B&D moto-tools have lots of slop in the shaft bearings. Wouldn't that runout negate any advantage of the Unimat's nice tight tolerance headstock?
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#25 Phil Hackett

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Posted 25 January 2017 - 06:37 PM

Sloppy bearings would make consistency problematic. I don't see a Dremel in any of the pictures and have no idea how good Proxxons are.

 

It looks like Gary isn't having any trouble.


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