The Shop > Finishing

sourcing 600 & 800 grit carborundum in the UK

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pipemakermike:
I just remembered that I have a pot of rouge - no idea if it will work - I use it for polishing violin varnish

Bluechip:
I seem to remember from my early days at work, the firm used either powdered pumice or rottenstone as a non-embedding abrasive.

Ground up in oil. Can't really remember which it was though.

( It was last century, or the last millenium if you want to really rub it in ... )

Otherwise there is a proprietory US(?) compound called 'Timesaver' ... excellent, but I don't know that it is available in UK anymore.
Never cheap, but just the dogs gonads etc.

There are several grades depending on what you're lapping..

Once had some ( green tin ? ) .. long gone ..

BC

75Plus:
Timesaver is still available but, as BC noted, it is priced right up there with Mother's Milk.  :jaw: 
$72 dollars per lb.

http://www.newmantools.com/lapping/time.htm

Joe

Fergus OMore:
Mike,
           Apologies if there is the 'teaching people to suck eggs' thing. It is certainly not intended!

However, I recall 2 quite important references. One is the freebie of the Holzapffel books and apart from a seemingly myriad of information, describe different abrasive and how to sort out- what you create. Great stuff but there is the classic Amateurs Lathe by Sparey who, if my memory is holding out, described using powdered brick dust at some point or other.

Both are well worth a place in anyone's shelf.

Regards

Norman

PekkaNF:
I haven't lapped much cylinders, but pretty much all I read about powder laps has basically fallen into two groups:

1) Diamond seems to be used such way that the lap is "charged" i.e. the diamond dust is forced into lap with hardened roller or plate and all extra is brushed away. I don't recall it used "loose". I think that the idea is to use trough as a single grit.

2) Softer abrassives seems to be used loose, often in oil or such paste, where the idea is in amateur use that the particles breaks down to new smaller and sharp particles. Can't remember exactly, but I think it was GEO Thomas who said that the amateur will get away with a single grit.

Laps must be much softer the part and you should never use the working part as a lap. Once I tried to make one taper fit better to boss and just tried to cut corners using a fine valve grinding paste and "couple of go's". It didn't improve. Two wrongs don't make one right in this sphere.

PekkaNF

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