Burnishing Machine Rotation Speed

[Geoff]

I am considering either buying a  machine  (https://www.ebay.co.uk/i/153186676769?chn=ps)

Or, possibly converting a bench grinder that I have. The question I am asking, is about the RPM. Both options have a RPM of about 3000, which I thought was a bit high.

Is it possible to burnish safely, without generating too much heat with 3000RPM? I notice that the Cobra machine has a speed of 2-3000RPM

Can the high speed be compensated for by reducing the pressure applied?

[Matt S]

I've been using that since they same out but saved a few beer tokens and provided my own motor (cheapest bench grinder I could find). Still using the burnisher and motor to this day but the sanding drum sits in the dark corner where I threw it in a couple years ago.

The burnishing wheel is fine -- well balanced and works as advertised. My motor is pretty fast, about 2,900 RPM, which yes is close to the maximum you'd want at that diameter. (The issue is surface speed, rather than rotation speed alone.) There's an increased risk of burning the leather at this speed compared with a slower speed. Yes pressure can be reduced to compensate a little but you need a certain amount of pressure to get the edge to conform to the shape of the groove so there's a limit to how little you can apply and still be effective. After some initial issues and talking with Nigel himself I've found the the edge should be quite wet, which makes it less likely for the edge to burn. If you can obtain one a slower motor (1400 RPM for instance) would probably be safer.

As to the sander... it has a few issues. Biggest for me is that there is no facility for dust extraction. My lungs don't enojThere's also no rest or stop so you're relying on your eyes and hands to keep anything aligned, perpendicular or flat that needs to be. The abrasive is also an issue. It's fairly hard to get hold of for starters, and expensive when you can. You can cut it down from normal sheets I guess. There's a knack to getting the paper to sit flat and taught on the wheels but I couldn't crack it -- it uses an odd system with a bar which rotates inside a slot which simultaneously tensions and locks the paper. Never could get the hang.

[OLDNSLOW]

the safest is about 1700 rpm and slower, the slower the better without fear of burning the leather, you can always get a speed reducer at Harbor freight that is made for routers and use it on the motor to reduce speed.  I recently picked up a speed reducer to use on a car buffer that is being used a pool ball polisher and it works great.

[Geoff]

I have just seen this

https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.co.uk%2Fulk%2Fitm%2F183418944943

What do you think?

[Matt S]

3 hours ago, Geoff said:

I have just seen this

https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.co.uk%2Fulk%2Fitm%2F183418944943

What do you think?

I think I wouldn't touch it with a pole. Turns way too fast, same issues as the Nigel Armitage design, questionable electrical safety, and we have no knowledge of what the burnishing wheel is made from or what it's finished with -- or in fact that it works effectively.

More importantly perhaps: what do you think of it?

[Geoff]

1 hour ago, Matt S said:

I think I wouldn't touch it with a pole. Turns way too fast, same issues as the Nigel Armitage design, questionable electrical safety, and we have no knowledge of what the burnishing wheel is made from or what it's finished with -- or in fact that it works effectively.

More importantly perhaps: what do you think of it?

According to the machine description, it has s variable speed function.

That's what interested me. But it does seem to be too cheap to be any good??

[JLSleather]

Get a drill press, put whatever burnishing wheel you prefer in it.  I like mine (about 1" dia) running 500-600 rpm. That's HUNDRED, not thousand.  Harbor freight bench model is about $75, last for years.

[Matt S]

6 hours ago, Geoff said:

According to the machine description, it has s variable speed function.

That's what interested me. But it does seem to be too cheap to be any good??

Variable or not, the top speed of that motor is around 8,000 RPM, which is about twice as fast as the maximum I would recommend in that wheel size. To me that says that this machine was designed and sold by people who don't work leather -- what else will be inappropriate? What's the wheel made from and how's it finished? What are the sizes and shapes of the grooves -- and are they going to be suitable for actual use?

Yes it may be fitted with a variable speed control but my experience is that these sorts of things tend to rob all the power out of the motor, especially on cheap machines. Speed control on a burnishing machine doesn't need to be nearly as precise as a drilling machine, lathe or even a tool grinder -- nor does it need to be variable if the wheel size is fixed.

If you have a bench grinder already just get a burnishing wheel from Just Wood/Nigel Armitage -- £78 isn't cheap but it's good quality, designed by a very experienced leatherworker and cheaper than this piece of questionable Chinesium.

@JLSleather gives another sensible source of motive power -- a drill press. This allows variable speed with no loss of power.

[Geoff]

Thanks for your helpful replies.

I am going to go along with the drill press suggestion.