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Hello from Thailand

I bought gramophone needle sharpener but o-ring rubber is lost. I don’t know about size of it (inside and outside). Someone can help me about it?

I give the typical tyre sizes on this page of the BCN website: http://www.burmesecolourneedles.com/spares

IM Pointmasters can vary slightly more than other sharpeners in the size of tyre they need - and/or the height (thickness) of the cardboard strip can vary slightly - unlike other designs of sharpener, these two dimensions need to be roughly in correct relationship to each other. Most o-rings nowadays seem to be 60 or 70 degrees Shore hardness (softer is better as it's more compressible) - I'm pretty certain the original tyres were softer.

I also believe that original o-rings made for Pointmasters were softer than o-rings, and I also suppose they were of a "custom" gauge.

If my memory doesn't fail, I experimented with 9x3 mm and 9x4 mm gauges. The 3mm is definitely too small, to the point of being unusable. The 4mm is a bit too thick and the resulting tips look more sleek than those originally provided by Orchorsol. The flatness of the sandpaper strip also gets very critical, with some areas effectively resharpening the tip, while others remain out of reach. However, it can be used with success.

I know that the intermediate 9x3,5 size exists, however I can't find it at retail: I've only seen it coming from China in 1K units bags, which completely put off any willingness to experiment with them. I ignore if o-rings are also available in inches, which may possibly result in some other intermediate gauge.

Unused old stock rings and sandpaper strips sometimes appear on eBay. Some people fit the rubber tyres used on older Dinky Toy cars, which I believe are still being manufactured for the diecast model collecting hobby.
Emery boards used by ladies to file their nails can be modified to fit the IM sharpener.

In my opinion (and I know also in Orchorsol's) the original sandpapers are way too grainy for the task, and they also get scraped down to the cardboard very quickly. Personally I craft my own strips by re-cutting a circle of 240 gauge tissued sandpaper for eccentric grinding machines.

Would these be any good? Appears to be the dimensions Marco is suggesting although I have not idea how hard the rubber is.
eBay item number:183999899892
Iain

I never really tested it, though! It may not work at all, just as the 3mm.

The dinky (or Corgi if you prefer!) tyre method works very well. They’re cheap too.

According to this list:

https://player.slideplayer.com/76/12713 ... lide_2.jpg

there are many sizes of tyres for Dinky Toys cars. Which are the ones that are reported working so well? Frankly, I have some concerns abot these tyres not being flat but treaded. Also, being the 17mm type already 4,75mm thick, it doesn't seem that any of them really has the appropriate size.

Check Orchosol’s post out with the website link. The sizes are the.

Don’t get the ones with tread on- you can order smooth ones.