Power Tool speed reducer

[Fallingup]

Hi. I'm thinking about getting a mains sander like the one below and using it for polishing. To do this I would need to be able to reduce it's speed considerably. Ones with speed control seem to be very expensive and not worth it for my use. What I would like to know is if it is possible to buy some kind of off the shelf adjustable voltage/power reducer to slow the machine down. Thanks.

[Promised Land]

I have this version but I guess they’re all generic inside and they just put their own branding on it but they don’t rotate very quickly at all, certainly not angle grinder rpm, I’d say the belt is about 70-80 rpm.

[Fallingup]

Are you sure? The Sealy disc sander is 2850 rpm and the belt is 440 rpm according to their website. It's the disc that I would be using the most.

Edited by Fallingup on Friday 17th May 20:54

[Caddyshack]

Surely there are purpose made polishers?

[Fallingup]

Caddyshack said:

Surely there are purpose made polishers?

I want to try my hand at lapping watch cases. A purpose built one is over a grand.

[Caddyshack]

Could you use an orbital car polisher as they have variable speed and polishing attachments. I have put mine in a workmate before and used the locked on trigger button, I polished up alloy tubes like that.

[Caddyshack]

Screw fix titan is £45 and has 6 speeds

[Fallingup]

Pity. I was hoping there was some simple adapter with a speed control knob that the sander could be plugged into. Thanks for the replies.

[Caddyshack]

Fallingup said:

Pity. I was hoping there was some simple adapter with a speed control knob that the sander could be plugged into. Thanks for the replies.

You can buy voltage regulators / adapters but I think the motors might not be infinitely adjustable and I guess they stall at some point.

[hidetheelephants]

The disc/belt sander has an induction motor, you could use a speed control but they have poor torque and are reliant on a not very efficient fan on the motor shaft for cooling and slowing it down and applying a lot of load at a reduced speed is quite likely to cause overheating unless you take a lot of care.

[Fallingup]

Yes. It would be a bit heath Robinson and may cause damage but I'm willing to give it a go. It's just a hobby. Would something like this be a possibility?
MaxEarn Electronic Voltage Regulator 4000W 220V, SCR Adjustable Electric Thermostat Regulator, UK Plug Power Regulator, Variable Motor Fan Speed Temperature Controller https://amzn.eu/d/fOjFAOR

[Caddyshack]

Fallingup said:

Yes. It would be a bit heath Robinson and may cause damage but I'm willing to give it a go. It's just a hobby. Would something like this be a possibility?
MaxEarn Electronic Voltage Regulator 4000W 220V, SCR Adjustable Electric Thermostat Regulator, UK Plug Power Regulator, Variable Motor Fan Speed Temperature Controller https://amzn.eu/d/fOjFAOR

I think that would do it but I would look for a U.K. plug and spend a bit more, it worries me that they didn’t even translate things like Temperature Correctly etc…I suppose you wouldn’t leave it running unattended but I think too cheap might fail

[Fallingup]

Caddyshack said:

I think that would do it but I would look for a U.K. plug and spend a bit more, it worries me that they didn’t even translate things like Temperature Correctly etc…I suppose you wouldn’t leave it running unattended but I think too cheap might fail

Thanks
I can easily change plugs and the Chinese are not renowned for their English instructions. I'll give it a go. What could possibly go wrong! Cheers.

[Simpo Two]

Lowering the speed won't turn it into a polisher, you need to change the sandpaper for something much finer.

There must be something like a small bench polisher with a range of mops for way under £1,000.

eg a quick hit from Amazon: https://www.amazon.co.uk/Polisher-Polishing-Machin...

Edited by Simpo Two on Friday 17th May 22:14

[finlo]

I slowed down a cooker extractor with a dimmer switch many years ago pre electronic dimmers don't know if it would work now with these modern things.

[hidetheelephants]

Simpo Two said:

Lowering the speed won't turn it into a polisher, you need to change the sandpaper for something much finer.

There must be something like a small bench polisher with a range of mops for way under £1,000.

eg a quick hit from Amazon: https://www.amazon.co.uk/Polisher-Polishing-Machin...

Turn a sanding belt inside out and daub some rouge on it.

[GT9]

The word 'considerably' is the salient one.
I'd say that just reducing voltage without reducing the frequency won't give you the speed reduction you are looking for if it's an induction motor.
The motor will possibly just stall, even under no load, or you'll burn out the windings.
Using a frequency converter is a lot more expensive, as you've already discovered.

[Fallingup]

Well I'm willing to give it a try just so I know for sure. Thanks all.

Edited by Fallingup on Saturday 18th May 07:33

[akirk]

I use polishing mops on my lathe giving me speed adjustment from about 200 rpm to 1200 (mop rating not lathe capability)

You could probably buy a cheap second hand lathe and mops for less…

[Fallingup]

akirk said:

I use polishing mops on my lathe giving me speed adjustment from about 200 rpm to 1200 (mop rating not lathe capability)

You could probably buy a cheap second hand lathe and mops for less…

Apologies. I didn't make myself clear. It's lapping I'm trying to do which is a kind of polishing. Thanks.