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G&S Tire Grinder


MrFlippant

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G&S Tire Grinder
A new kind of tire truing machine, suitable for most kinds of 1/32 and 1/24 wheels and axles.
 
20230421_213034_HDR.thumb.jpg.f7d62633708501cba7a375abeb5ec7c6.jpg
 
First, the name. G is for Gaub, or Greg, whichever you prefer. S is for Samson, as in Dennis Samson. His original design for a rotating sanding drum machine for whole axles (e.g. pressed on wheels) inspired this design to a great extent. It was with his input and feedback, along with others in the community, that this machine was finally realized as shown. I also owe thanks to Giacomo Verlini, aka JamieG from Sweden, for his design for the sanding sleeve drums that I have used for this machine. You can find his Tyre Truer MKIII for slot cars 1/32 and many other great models on his Thingiverse page.
 
This machine is intended to be a "good enough" machine to get casual racers started with their tire truing needs. It is not intended to replace or compete with precision milled machines for high level competitions. As it's designed to facilitate tire truing on a variety of 1/32 and 1/24 size tires on pressed-on plastic wheels, it's not meant for racers who are using precision metal wheels, though it can also be used for those kinds of wheels/tires. Someone who has no cars with pressed on wheels should probably look elsewhere for a more precise machine, if they don't already have one.
 
This machine will be provided free to download, print, and build your own. The license is Creative Commons, Attribution, Non-Commercial, Share-Alike. From a practical standpoint, that just means no one else is allowed to market or sell the files, plans, prints, or completed machines without my express permission. Credit to my project must be given any time the machine is shown or shared. Since I'm releasing it as open source, the "Share-Alike" part of the license means that if you design a machine that is derived from this design, you must also share it as open source with the appropriate credit to me. If you are contacted by someone to print the parts as a printing service, you have my permission to do so, but you cannot advertise that you are printing the parts for sale. I reserve the right to market and sell prints and/or machines until I am no longer able to do so. Pricing for prints/kits/machines TBD.
 
All of the parts are designed to be printed on any FFF (filament) 3d printer with no need for supports. PLA can be used, and is preferred, for the majority of parts due to its rigidity. Parts that are subject to heat, such as the pulleys and sanding drums, should be printed in PETG, or similar high temperature material. The largest piece, the base plate, measures 168x120mm, and so should be able to be printed on most machines, even many of the "mini" printers.
 
 
BOM
  • 15x - M3x10mm Socket Head Cap Screws
  • 12x - M3x6mm Socket Head Cap Screws
  • 2x - M3x6mm countersunk screws
  • 2x - M3x4mm set screws
  • 15x - M3 Square Nuts
  • 1x - 1/4-20 x 4.5" Hex Head Bolt, fully threaded
  • 2x - 1/4-20 x 2" Hex Head Bolt, fully threaded
  • 3x - 1/4-20 x 7/32" Hex Nuts
  • 1x - 1/4-20 Nylon Lock Nut
  • 1x - 1/4-20 Acorn Hex Nut
  • 1x - 1/4x3/8x1/2" steel spacer
  • 1x - RS550 DC motor
  • 1x - 1x7 20x53x13mm Conical Spring
  • 4x - R188 bearings
  • 3x - 1-1/2" ID, 1-11/16" OD, 3/32" Width O-Rings
  • 2x - 1"x1" spiral band sanding sleeves, 80 grit
 
Printing instructions:
 
Most parts can be printed in PLA, but there should be at least 4 perimeters (1.6mm thickness) and most parts should have a strong and dense infill, such as 30% Cubic.
 
The round/pulley parts should be printed in PETG or other high temp material, with a random seam position to reduce a “lump” from an aligned seam.
 
The small pulley for the motor, and the split pulley for the slot car axle should be printed 100% infill because they need set screws to stay in place and will split easily if not solid.
 
Review the photos and STEP file to confirm assembly.
 
Assembly guide and/or video will be forthcoming.
 
 
Edited by MrFlippant
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Key Features of the G&S Tire Grinder

  • One motor turns all axles
  • Only two screws to remove/replace the entire grinding assembly for different grits
  • Screws beneath the ball bearings to adjust parallel
  • Spring loaded axle carrier to allow "grind and release" truing methods with ease
  • Indicator knob for precise repetition of tire diameters as needed
  • Consistent tension of o-rings due to double-pulley design
  • O-rings can easily be moved side to side to accommodate various axle configurations
  • standard 1/32 bushings snap into axle carrier, but V-shape still allows smaller or larger bushings or bearings to stay in place
  • Distance between sanding drums accommodates most 1/24 and 1/32 wheels/axles
  • sanding surface cannot contact axle pulley/o-ring
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  • 1 month later...

G&S Tire Grinder Pricing (not including shipping)

$150 USD - Fully assembled and tested machine, ready to get to work.
$100 USD - Complete kit of parts including all printed parts and hardware.
$50 USD - Printed parts only.
$50 USD - Hardware only.
$25 - Complete Sanding Spindle (36, 80, 120, or 240 grit)

Power Supply is not included.
Shipping extra.
International orders welcome.

To place an order, PM me here, or email me at ggaub@ggaub.com

Edited by MrFlippant
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Small, but important update. I was asking too much of the all-plastic split pulleys for the slot car axles. After some adjustments, I was able to fit a square nut into the pulley. This gives the pulley a lot more holding power without the risk of stripping the plastic with the set screw. The model files on Printables have been updated, and all machines/kits shipped from today will come with these new pulleys. There is one for 3/32 axles, and another for 3mm axles, and both have identification markings on the model to more easily tell them apart before attempting to fit to the axle.

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  • 8 months later...
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I was asked to work out the actual change in dimension according to the indicator knob. Here's the math: 

The 1/4-20 bolt is 20 threads per inch, so thread pitch is 1/20" (0.05" or 1.27mm). 
The ratio of center points (axle and knob pivot) to the axle bracket pivot point is 1.226, so the wheels move that much more than the knob does.
Multiply 1.27mm by 1.226 and we get 1.55mm per full knob rotation, or 0.13mm per whole number. 
There are 72 notches, so each notch would be 0.0215mm.

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I've completed the G&S Tire Grinder Setup and Use document. Much of the same information as in the video I recently posted, but with the addition of instructions on how to replace the various rubber bands on it. Please feel free to offer feedback, whether it's a typo or suggestion for better instructions somewhere. I'll update the document as appropriate, but the link will remain the same.
https://www.ggaub.com/slots/GnS-Tire-Grinder-Setup-and-Use.pdf

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11 minutes ago, Vinno said:

Probably a good idea to point to the forum from Facebook to get more interest. Some good articles like yours are on here and the more interest the better.

As much as I'd like there to be "one source" that everyone goes to, or finds when searching, I know that's just not practical, let alone possible. So, I'm forced to cross-post everything to all the different places, including a half dozen web site forums and another dozen FB groups. Without spending every penny I earn on advertising, that's about the best exposure I can come up with. At least this way it doesn't look like I'm choosing favorites by linking to a single forum.

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4 hours ago, MrFlippant said:

As much as I'd like there to be "one source" that everyone goes to, or finds when searching, I know that's just not practical, let alone possible. So, I'm forced to cross-post everything to all the different places, including a half dozen web site forums and another dozen FB groups. Without spending every penny I earn on advertising, that's about the best exposure I can come up with. At least this way it doesn't look like I'm choosing favorites by linking to a single forum.

We appreciate your input, you put a lot into the hobby and the more reference material we have the better our forum is. It’s good to have some options on certain products. 

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53 minutes ago, Vinno said:

We appreciate your input, you put a lot into the hobby and the more reference material we have the better our forum is. It’s good to have some options on certain products. 

Yep. that's why I try to remember to share across all the forums and groups. Alas, there are WAY too many Facebook groups to account for, but I hit the high membership count ones I know about.

It would be nice if the bugs still plagueing this forum were resolved, though.

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1 hour ago, MrFlippant said:

Yep. that's why I try to remember to share across all the forums and groups. Alas, there are WAY too many Facebook groups to account for, but I hit the high membership count ones I know about.

It would be nice if the bugs still plagueing this forum were resolved, though.

What bugs are you seeing as I don’t have any issues on my end? It seems to depend on what browser people are using from what I have heard before.

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8 hours ago, Vinno said:

What bugs are you seeing as I don’t have any issues on my end? It seems to depend on what browser people are using from what I have heard before.

What browser should I be using? What do you use?

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7 hours ago, MrFlippant said:

What browser should I be using? What do you use?

I’m using Safari on an iPad in general. I know it shouldn’t come down to that but it seems a lot of software packages cater to one type of browser more than another. 

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I've tried various browsers, and I'm fairly confident that this issue is not browser related, as the forum software produces it's own error, not a browser error. My main problem is no longer being able to put video inline. It used to automatically parse video URLs into inline video, but now it just pops an error whenever you post a video URL, and it becomes a plain link. Not the end of the world, just an annoyance. I've found no other way to make it do the inline video thing any more. I believe there are other, minor annoyances hanging around as well.

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