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lapping compound

the thing is, timesaver is not available over here and im reluctant to pay over 3x the price including shipping. they say non-embedding and garnet, so i thought it might be an alternative.
 
I strongly suspect that Timesaver is also garnet based. Yes they do have two versions, but even the version for iron is very soft.

I got some Timesaver from here in the UK. It is expensive and their shipping to Ch is also expensive. I would be tempted to try the Brownells product on a piece of scrap brass/bronze and then use that if it were ok. I would certainly have used the Brownells product for my (cast iron) job if I had known about it!
 
Feldspar family based, rather, which see. Why "suspect" when you can easily "just know"?

ANY abrasive used in industry must be of known composition.
Too many potential unwanted side effects, otherwise.
Not just embedding.

Toothpaste is usually "micro" Silica. Different mineral.

Feldspar (which is just below quartz on the Mohs scale) could work, but Feldspar may be too hard for Bronze, and too soft for steel. But it's easy to just try.

The Mohs Scale of Hardness for Metals: Why It Is Important


However, that's not what's in Timesaver lapping compounds, according to their Safety Data Sheets.

Green (for hard metals) is basically powdered crystalline quartz plus detergent. So, ordinary household cleanser, like Ajax, could work.

Yellow (soft metals) is half crystalline quartz and half Barium Sulfate, also plus detergent.

Barium Sulfate is 3 to 3.5 on the Mohs scale, same as bronze, and is available cheap on Amazon.
 
Garnet lapping compound is known to be non embedding. It is apparently used for lapping valves on brass instruments. This thread gives some more info: I neded lapping compound -- Is US Products Co still in business?

US Products Co manufactures Garnet lapping compound and references it as non embedding:
GK-10 | United States Products Co.

I have personally used Garnet to lap two hardened steel pieces together without any embedding issues. Embedding can be an issue with many lapping materials anytime your lap is not significantly softer that than the material. It can be pretty easy to embed diamond compound in 60RC steel surface if it is driven in with another 60RC part.
 
Timesaver ingredients are:

Green label for hard metals:

Almandite and Pyrope Garnet - 60%

barium sulphate, natural - 20%

Quartz (SiO2) - 20%

Sodium dodecylbenzenesulphonate 1%


Yellow label for soft metals:

Quartz (SiO2) - 50%

barium sulphate, natural - 30%

Sodium dodecylbenzenesulphonate - 10%

Sodium Sulphate - 10%


This is off an old sheet that came with timesaver I bought many years ago. I have every grit of both green and yellow. Although not cheap, a can lasts forever. I still have a can of yellow I bought in the 1970's.
 
If you have ever examined a lapped surface under magnification, you would never lap anything except a taper fit. The surface looks like the rocky mountains.

The double taper hard bearings on a watchmakers lathe, when new or unworn, should not appear polished. They need a matte, frosted surface for oil retention. The polished look is the result of wear, or wearing in.
 
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Timesaver ingredients are:

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This is off an old sheet that came with timesaver I bought many years ago. I have every grit of both green and yellow. Although not cheap, a can lasts forever. I still have a can of yellow I bought in the 1970's.

I wonder if the formula has changed since then. The SDS sheets I was looking at were circa 2013.

 
its a good point that brownells might be referring to q+t steel when mentioning "non embedding". scrubbing powder works to a certain extend, but removes sub micron amounts (at least in realistic time frames).

as to msds sheets, you find all kinds of weird stuff in there, sometimes not even declaring 20% of the composition. but it doesnt really matter. abrasives are not produced in a lab, where given proportions of chemicals would get mixed. they originate from natural resources. the minerals have very complicated and differing structures depending where they come from.

recently i had an interesting conversation with the owner of a company, that sells an abrasive somewhat similar to timesaver. hes been doing it for decades and used to get the raw material from an vucanic island in sicily, a kind of pumice stone. later the area was placed under conservation and now hes importing stone from the u.s. that gets mined by navajos somwhere in northern arizona mountains. it would be futile to make a chemical analysis of the material, because its exact structure is where its abrasive properties come from. its not just size (grit) and hardness but much more that matters.
 








 
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