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[MadMike]

For polishing the sort of small work found on a bike I reckon that you would need about a 1/3HP motor on the grinder. After all people make a passable job using electric drills of frankly dubious age and power.

[MadMike]

Sorry I forgot to add that many small lathes and milling which are used by hobbyists to cut metal have motors of less than 1 Imperial Horse.

[Mark M]

1 Horsepower equals just under 750 Watts.

REgards, Mark

[MadMike]

You are not wrong Mark. I knew that when I posted. My lathe has a 1HP motor and can swing 10" diameter and drill and turn just about anything in any material that size range. The point I was making was simply that a 1/3HP motor should easily cope with a bit of polishing.

[Mark M]

Agreed Mike but it's not just wattage. The motor winding type influences torque but maybe even more important the mass of the rotating parts of a lathe helps resist stalling. These small cheap grinders are ok for drill sharpening etc but just slow and stop under real pressure. Yes, I do have one unused under the bench!

REgards, mark

[jefrs]

I have tested the mains ('cos we had to for work) and found it to be 248VAC, don't do this at home UK mains is still 240-250 VAC even if Euro Volts is 220-230. Every country in Europe still uses their own old voltage (because it is too expensive to change the generators), just that the average is 220-230. For some reason southern countries use lower voltage, northern have higher ones. Problem is equipment now come rated for 230V and we shove nearly 250V into it. The Lick is rated at 240W at 230VAC, on 250VAC it will develop 260 Watts.

[Mark M]

Jefrs, European standard voltage is "harmonised" at 230 v but was executed in a typical Euro fudge, see here: http://coffeetime.wikidot.com/uk-eu-mai ... monisation Higher voltages read locally are not unusual and due to all sorts of reasons not interesting enough to list here! (I am basically an electrician.)

REgards, Mark

[Thack]

Mark M writes: "Rather sneakily our power supply has changed over the last few years to standardise with the rest of Europe and is now 230v."



I agree with jefrs. The UK voltage was not changed. Rather, the EU voltage was agreed as 230V plus or minus a fairly large margin. Our 240 volts lies well within that margin, as does the 220V used in some other parts of Europe.

[Thack]

jefrs writes: "Problem is equipment now come rated for 230V and we shove nearly 250V into it. The Lick is rated at 240W at 230VAC, on 250VAC it will develop 260 Watts."

Actually, no, the rating includes the tolerance margins built into the EU standard. So a nominal 230V rating includes both the 220V and 240V supplies used throughout Europe. All ratings have tolerance margins. In other words, our 240V does not in any way "overload" a nominal 230V power supply.



Of course, if the appliance runs straight off the mains, and has no internal switching power supply, then it will generate a bit more power than when it is connected to a 220V supply, as jefrs says.

[Gwilly]

Having done a bit of polishing over the years i can only speak as i find..

Namely don’t use anything cheap or Chinese when it comes to things like abrasive wheels, grinders, anything that can fly apart or disintegrate in normal use..

Google, "Chinese Escalators" if you want proof of their engineering prowess..

150-250 watt motors are fine for 3” polishers, Jewellery and small items but for 6” wheels a minimum 370watts and 8” something in the region of 500watts may be just enough..

Its surprising how easy it is to stall the machine, even when applying moderate pressure polishing something like a gearbox outer cover, or primary cover with a six inch wheel.

Add to this the length of time in continuous use, Even a 500 watt motor will get fairly hot given a hours work and you may have to stop operations or risk burning out a lower rated motor..

In this case a good biggun will always beat a good littleun..



http://www.metalpolishingsupplies.co.uk ... ng-kits-1/