To lap or not to lap

[T Bredehoft]

glass is a super-cooled liquid, and never stops flowing.

True to a point. for all practical purposes, glass is a solid below 900ºf. Window glass that is thicker at the bottom of the window was put that way on purpose, it didn't 'creep.' Anything else is old wives' tales.

 

[Mini lathe owner]

Mini lathe owner
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Yesterday at 9:16 PM

• #1

Can anyone give me advice on the best lapping compound grit to use when lapping the cross slide and compound slide on my mini lathe.

I have heard that Timesaver is a good brand. Timesaver has a Yellow and Green line. The Green line is what is used on steel. My question is of the 4 grits that they offer,

Coarse: 40 grit
Medium: 80 grit
Fine: 220 grit
Very Fine: 320

Which grit would you recommend?

If not Timesaver brand, what compound and grit would you recommend?

 

[Watchwatch]

Time saver is non embedding and breaks down quickly.

Very fine. It might take longer but better safe than sorry. I have no idea if what you are doing is a “good idea”. It’s what I’d use if I had to pick.


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[addertooth]

I probably would not bother trying to rehabilitate the factory Gibs. I would buy higher quality Brass Gibs from Little Machine Shop and use them. They start out flat and true from LMS, and brass is a lower friction material than the factory iron/steel gibs. As for the dovetails and ways. I would not use lapping compound, but rather KNOWN flat stones on the surfaces. The use of bluing compounds, as suggested earlier is spot on. Chances are the dovetails and ways have errors that are much bigger than hundreds of a thousandth of an inch. Lapping does amazing things when the error is extremely small. Known flat stones are probably a better choice for removing larger errors found on Chinese lathes and mills. The usual cautions apply when using any abrasive on a mill/lathe.