Bench Grinder/ Polisher

[MerlinV12]

Hi all, can anyone give some constructive advice on a suitable wattage bench grinder that I can convert to a polisher, for example would an 8" wheel be better than a 6".
Any advice gratefully apprerciated.

John

[mickwinf]

Hi John I have two set up for polishing, one cheapo one from aldi and a newish hilka one. The main problem is if you put too much pressure on the mop they will slow down and overheat, so you should limit the time to about 10 mins then let it cool down. I guess the higher wattage motor the better, but the bigger the mop the more it will slow, so i use 4 inch mops which enable me to put a bit more pressure on. Hope this helps, regards Mick

[sweetpeauk]

Bigger wattage the better. 4-6" disc's should be ample for a converted bench grinder, also 1/2 thick discs will slow down less when putting a bit of pressure on. When I was living in India I got hold of a 1HP dedicated polisher and that is just about OK with a 10" mop. also use good face mask and have some old sheets to use as a catch net for when that small bit gets ripped from your hands and fired at the floor at 300mph.

[sweetpeauk]

Other tip is that don't be in to much off a hurry to use the polisher. I always use wet and dry and Garryson black/blue abrasive blocks to get rid off all corrosion and pits before polishing, this also aids in keeping the surface as flat as possible and edges true. then a quick buff on a converted grinder should give great results. Also with great care you can polish some plastic's to remove light scratches and put a gloss back, I have done light lens and even the sides of the black idiot light console on my 400. 

[MerlinV12]

Thanks for your advice guy's, all I've found so far is:

http://www.ebay.co.uk/itm/261153864602?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649

http://www.ebay.co.uk/itm/250456774734?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649

or convert this old AC motor with an arbour, what do think

http://www.ebay.co.uk/itm/130837773354?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649

[UK Pete]

I am not sure but have heard you need 2500 to 3000 revs for a decent polish speed

[K2-K6]

That old 1hp motor looks the most suitable if you are comfortable converting it.

A bench grinder doesn't need so much grunt as the inertia in the wheel once spinning contributes a lot to the intended use which is things like dressing and shaping machine tools and you don't use much heavy pressure in this as you try to avoid heating up the work piece too much.

Used with a mop, then that inertia wieght is not there AND you often slow the wheel more with pressure so they are not ideal for polishing.

You need to get an approx linear speed as a bigger motor will turn a larger mop and you won't be forced to get a higher spindle speed.

That 300mph comment made me laugh as I remember polishing our ashtray projects at school and having them rattle round the sheild and zing across the workshop when you caught an edge.

[MerlinV12]

K2, that remark about metal work classes brought a smile and a few memories of my school days too, happy days.

[MerlinV12]

Ok, so a week or so has passed and I've aquired a 1HP motor and the polishing bits have turned up today but I have a query. The motor shaft rotates clockwise, should the adaptor be left or right handed. The second question for those that have done this before whats the easyest way of removing the paint that manufactures use on crank cases.

[Mitchv60]

The second question for those that have done this before whats the easyest way of removing the paint that manufactures use on crank cases.

I haven't done it yet but I'm getting mine vapour blasted.

[MerlinV12]

Thanks for the input guys I'll take everything on board and see how we go.

Many Thanks

[K2-K6]

Not sure I understood your question about left or right handed.

Most that I've used have had the top of the wheel coming toward me in use, so that would mean having the motor in front of you with the shaft pointing to the left side if that's what you mean....hope that helps but don't know if I've answered it for you.

post again if not.

[MerlinV12]

Not sure I understood your question about left or right handed.

Most that I've used have had the top of the wheel coming toward me in use, so that would mean having the motor in front of you with the shaft pointing to the left side if that's what you mean....hope that helps but don't know if I've answered it for you.

post again if not.

K2, what I meant was the arbour or adapter for the motor shaft that screws into the polishing mop is quoted as being right or left handed. My motor revolves clockwise ( I was sent a right handed adapter ) but even though I tighten the mop onto the shaft it sometimes flies off only to disappear to the other end of the garage and sometimes it stays on, go figure.

[K2-K6]

Yes, that's clear now....and I think you should need a left hand thread arbor so that when you tighten the wheel onto there,  it's by turning in the opposite direction of shaft rotation.....as the other way it's more by luck that the friction keeps it on some of the time and natuarally unwinds when this is overcome.