Bench grinder to polisher

[colin hamiltonParticipant @colinhamilton16803]

So I'm looking to convert my bench grinder to a polisher. I see you can buy tapered spindles that go onto the grinder spindle.

Are these any good?

Are they held on by the grub screw or do they screw on?

Is it possible to make on my lathe if I don't have a taper turning attachment?

Thanks

[colin hamiltonParticipant @colinhamilton16803]

[Frances IoMParticipant @francesiom58905]

mine screw on (they come as a handed pair)
Bought them years ago from Axminster as part of a polishing kit – not expensive and probably not worth making yourself

[roy entwistleParticipant @royentwistle24699]

They usually screw on but note that the left hand side has a left handed thread. it's possible to mount the wheel as one would grinding wheels but not as easy to change as those on tapers

[noel shelleyParticipant @noelshelley55608]

The idea works ! You have a lathe so buy the solid tails and bore and thread to fit your grinder shafts but note that they are handed so one is left hand thread, not a problem just buy a L/H tap. Another sorce of good polishing motors is a .55 0r .75 watt pump motors, they will be 2 pole so 2800 RPM ! Strip the pump off, unscrew the impellor and fit a mop tail. If flange mounted, make a mount or weld a lump of 4" channel iron on the outside with 4 holes in to screw down. You will need to wire it up, if you take this route come back and I will help there. Good luck Noel.

[Ex contributorParticipant @mgnbuk]

How sucessful this will be will depend upon how powerful your grinder is & how much polishing you wish to do.

Most budget grinders are not very powerful – typically 250-375W. This isn't an issue with a tool grinder as, generally, you don't apply much pressure when grinding. But it is easy to stop one when attempting other operations – I have a 6" wire wheel on one end of my bench grinder for general derusting & deburring & it is very easy to stop the machine while using it. I have not managed to stop it while grinding.

For polishing I have a 0.75KW single phase motor with a suitably parallel bored "pigtail" attached. It is clamped in a Workmate by the feet when used. I can't recall the size of the mops I have without a measure-up, but think they may be 8" & I can stop this machine as well if I get too enthusiastic.

Be aware that polishing is a hot & dirty business !

Nigel B.

[Gary WoodingParticipant @garywooding25363]

Mine are attached by grub screws.

If you've never done polishing with a mop before then take great care not to catch an edge in the mop. It can snatch the workpiece out of your hands in an instant – throwing it with great force at anything in its way and causing damage and possibly injury.

[peak4Participant @peak4]

Posted by Gary Wooding on 02/01/2022 11:42:38:

Mine are attached by grub screws.

If you've never done polishing with a mop before then take great care not to catch an edge in the mop. It can snatch the workpiece out of your hands in an instant – throwing it with great force at anything in its way and causing damage and possibly injury.

I'd go along with that; I think there's one or two items I've still to find.

My spindle, with a wire brush one end, and mop(s) the other, now rotates the opposite way to a conventional bench grinder, and I only polish/brush, on the top of the wheel, so that if anything does catch it heads away from me.
I'm not set up with dust extraction (yet), but have a cardboard box behind the contraption; I use one of the shallow trays from the fruit & veg section of my local supermarket.
It catches most of the dust, along with errant workpieces.

Bill

[Steve355Participant @steve355]

Posted by Gary Wooding on 02/01/2022 11:42:38:

Mine are attached by grub screws.

If you've never done polishing with a mop before then take great care not to catch an edge in the mop. It can snatch the workpiece out of your hands in an instant – throwing it with great force at anything in its way and causing damage and possibly injury.

I agree, my polisher is by far my most dangerous machine tool, having ripped numerous lumps of metal out of my hands and fired them across the workshop at the speed of a bullet. The trick it to stay away from edges that might catch… still seems to happen though. I have a Sealey polisher, it’s well made and one of my most used and best investments.

[VicParticipant @vic]

I bought my Pigtails from these folks at very reasonable cost.

**LINK**

[colin hamiltonParticipant @colinhamilton16803]

Thanks everyone, great advice as always. I would have never guessed it was one of the more dangerous evolutions!!

[SandgrounderParticipant @sandgrounder]

Posted by mgnbuk on 02/01/2022 11:28:53:

How sucessful this will be will depend upon how powerful your grinder is & how much polishing you wish to do.

For polishing I have a 0.75KW single phase motor with a suitably parallel bored "pigtail" attached. It is clamped in a Workmate by the feet when used. I can't recall the size of the mops I have without a measure-up, but think they may be 8" & I can stop this machine as well if I get too enthusiastic.

Be aware that polishing is a hot & dirty business !

Nigel B.

I use almost exactly the same set up regards motor and mop size and like Nigel I can stall the motor if I press too hard on the mop.

John

[noel shelleyParticipant @noelshelley55608]

On a converted grinder DO NOT use wheels/Mops bigger than 6" Some cheep ones are only 150w, This is nowhere near powerful enough. I would be very wary of running in reverse, the casting may be in your hand but the mop and spindle could be anywhere.! ! ! When using a buffing machine it is quite an art and very dangerous in untrained hands. The buffing soap(compound) is quite aggresive and even fine grades will remove detail or cut grooves in the work if you use the wrong technique ! I use 6" mops on a 750w motor and it works well. To start with use 2mops, a sizal for first stage ie from rough or as cast then a stitched cotton as a second. For a really high polish then use an unstiched cotton. It is as Nigel has said a VERY dirty job, wear a hat and close fitting clothes or a T shirt . Good Luck Noel.

[AJAXParticipant @ajax]

Posted by colin hamilton on 02/01/2022 10:44:49:

So I'm looking to convert my bench grinder to a polisher. I see you can buy tapered spindles that go onto the grinder spindle.

Are these any good?

Are they held on by the grub screw or do they screw on?

Is it possible to make on my lathe if I don't have a taper turning attachment?

Thanks

I bought some cheap mops from eBay or Ali express and was able to mount them directly to the grinder spindle using the existing nuts. Quality was good. I may have turned some washers/spacers to provide a good clamping force. The only drawback of this method (as opposed to tapered spindles) is the mops are more difficult to swap over, if that's what you need to do.

I have previously bought some tapered spindles online from a UK supplier (manufactured in India) and they were absolute junk. Supplier name *roops *ros if you wish to avoid them.

[colin hamiltonParticipant @colinhamilton16803]

Posted by AJAX on 03/01/2022 17:26:51:

Posted by colin hamilton on 02/01/2022 10:44:49:

So I'm looking to convert my bench grinder to a polisher.

I bought some cheap mops from eBay or Ali express and was able to mount them directly to the grinder spindle using the existing nuts. Quality was good. I may have turned some washers/spacers to provide a good clamping force. The only drawback of this method (as opposed to tapered spindles) is the mops are more difficult to swap over, if that's what you need to do.

I have previously bought some tapered spindles online from a UK supplier (manufactured in India) and they were absolute junk. Supplier name *roops *ros if you wish to avoid them.

Thanks I made the same doert of spindle and mounted it in my 3 jaw. Worked well but I don't want to be polishing on my kathe for obvious reasons.

[Peter SansomParticipant @petersansom44767]

I converted an old 6" grinder, needed to polish brass handles. Have not had any issues of the grinder stalling but if you are not careful the item being polished will go flying. The grinder is a 30 y.o. Ryobi,

[Clive FosterParticipant @clivefoster55965]

Something to be said for starting out with a lower powered grinder. Especially if you have something to hand or if E-Bay, Facebook Marketplace, local free ad paper or just asking around can score something for beer money.

Lot safer from the ripping things out of your hand aspect if the power is low enough that you can stall it. Low power means low pressure so polishing takes much longer but you have time to see whats going on. As Noel says the buffing compounds can be disconcertingly aggressive. On a proper machine the job can get away from you in nothing flat.

When actually put to the test you may also find that you don't actually have enough polishing to do for a decent set-up to be worth it. Not to mention the mess. Did I mention that polishing is messy, really messy. Yup seriously messy. Frankly if you have enough to do that a decently powerful set up is worth it you will need a dedicated area with shields and extraction. Around 10 minutes of serious polishing with an open mop will turn the average shed size workshop into the sort of disaster zone that needs everything pulled out to clean up. (The gremlin colony living under the bench will not be amused by having their stash of lost parts repatriated!) Half an hour? best wear a hazmat suit.

Don't shove polishing dust and compound covered overalls in the washing machine! Mistakes like that can be fatal or at least seriously expensive from the "new appliance so we need a new kitchen to match" viewpoint. By bye next loco fund! Squoshing around in a bucket outside two or three times is a domestically safe cleaning method. Doesn't help that first time or three you will almost certainly use too much compound adn the excess has to go somewhere.

My personal motor'n mop has been sitting on the shelf for about a quarter of a century "just in case". Its done a few re-furbed piano keys for my tuner brother and thats it. I have used the proper thinga time or three, objectively quite enough thank you.

Clive

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