G&S Tire Grinder

Kevan · 8th-Mar-24, 07:53 PM

(9th-Jun-23, 04:15 PM)MrFlippant Wrote: 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.

à la Prusa so must be a good idea Thumbup

MrFlippant · 8th-Mar-24, 07:59 PM

(8th-Mar-24, 07:53 PM)Kevan Wrote:
(9th-Jun-23, 04:15 PM)MrFlippant Wrote: 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.
à la Prusa so must be a good idea

Yep! Using embedded square nuts for most of the machine assembly was definitely inspired by Prusa's methods.
The trick with the pulley was using a different angle so that it fit in the small space available. :)

Kevan · 8th-Mar-24, 08:29 PM

Might work with printed wheels too...might need one each side to balance it though Thumbup

MrFlippant · 17th-Mar-24, 05:14 PM

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.

MrFlippant · 18th-Mar-24, 09:35 PM

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-Gri...nd-Use.pdf

MrFlippant · 21st-Mar-24, 07:56 PM

I've added a video tutorial on replacing the bands:

dazee · 8th-May-24, 08:36 AM

Awesome work! Even with those olde world sizes which over this side the globe took some collecting together :)

I think I will go a little less aggressive than the 80 grit.

MrFlippant · 8th-May-24, 02:01 PM

(8th-May-24, 08:36 AM)dazee Wrote: Awesome work! Even with those olde world sizes which over this side the globe took some collecting together :)

I think I will go a little less aggressive than the 80 grit.

Very nice! Looks great.
Yeah, I ship them with 120 now. It's a good middle ground between fast cutting and smooth surface. Not a perfect surface, but better than with 80.
Feel free to post your make on Printables. :)

dazee · 9th-May-24, 04:11 AM

I have posted the same on Printables now. Next job for me will be to make a little on/off switch and voltage controll to go next to it.

MrFlippant · 9th-May-24, 04:15 AM

(9th-May-24, 04:11 AM)dazee Wrote: I have posted the same on Printables now. Next job for me will be to make a little on/off switch and voltage controll to go next to it.

Much appreciated!

Did you see Geoff's Remix? He added a whole bunch of stuff and made it a standalone unit. Pretty impressive.