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Many, many years ago, I used automobile finish rubbing compound to lap some slides. It worked nicely. You have to be able to judge when to stop, wash everything out, and see what you have. You either stop at that point or go again. What method do you use and why?

TJ

Tim Jackson wrote: ↑Sat Nov 16, 2024 1:51 pm Many, many years ago, I used automobile finish rubbing compound to lap some slides. It worked nicely. You have to be able to judge when to stop, wash everything out, and see what you have. You either stop at that point or go again. What method do you use and why?

TJ

I've tried coarse and fine rubbing compound for car finishes as well as stuff sold by repair supply houses as piston lapping compound.
For pistons, rotors, and slides, I prefer Lava soap suds (created by hand), rubbed off into a bowl, and then mixed with something about the consistency of mineral oil. (I've thinned out 30-weight a bit with gasoline before. It's just as good as mineral oil.)

My very old school repairman uses pumice powder mixed with lard.

arpthark wrote: ↑Sat Nov 16, 2024 2:44 pm My very old school repairman uses pumice powder mixed with lard.

not much different from what I use (explained above).
I have a jar of pumice power, and do the same if I use up my bar of Lava soap, and don't wish to run to the store.
I prefer to use oil/grease which is petroleum-based as solvents (again: gas is the cheapest) chase them out of instruments very quickly (rather than having to scrub with Dawn)...

...a few drops of gas - and a little bit of Dawn - is cheaper than the considerably higher amount of Dawn required to chase saturated fats out of instruments...

' personal choices...

post script:
The last thing I did was a (used) Miraphone rotor (junk box) which (thank the Lord) was slightly too large for the casing from which a trashed rotor (music-store ruined) had to be discarded. I was extremely pleased with the results (as I typically am using pumice-bearing soap suds and a petroleum-based lubricant - again, thankfully). The other three rotors' fit (I would rate) are "very good", but the scrounged rotor's fit ended up being particularly excellent...rivaling (ok...I'm not claiming that I can MAKE rotors, so don't think I have the "big head") the fit of new ones.

All the above is good. I’ve used Lava in various capacities.

As far as prepared stuff out of a jar, I like the HETMAN UNI-LAP. Easy to use, doesn’t embed, and washes out pretty easily. I had some for a long time, but have since run out. I’ll probably buy some more.

I’d also like to add for the unfamiliar that sometimes people (ok, “techs”) try to fix badly aligned slides or damaged valves that actually need other attention first by lapping them into oblivion. You’ll only know that this has happened until after the deed has been done. Lapping permanently removes material. It’s the last step in the process, not the first.

With regard to cleaning petroleum products with Dawn. Before using Dawn add a bit of cooking oil to the petroleum and rub it in. It will mix with petroleum then when using Dawn the cooking oil enzymes lock better to Dawn than the petroleum enzymes so the dawn cleans better and faster. I learned this from auto mechanics.

I stick with garnet lapping compounds. Supposedly other types tend to embed into metal surfaces, continuing the lapping process, even after cleaning. My two cents.

My lap does not have a tuning slide.

Grainy surfaces that are formed from this procedure - regardless of the fine abrasive that's used - are going to hold on to whatever's on them within the grainy surface, and to get them off is going to require using a solvent and a rag and maybe even some pretty aggressive rubbing in a bunch of different directions multiple times. When I finish fitting slides, pistons, or rotors, I take them back out several times over a period of a couple of days of playing them in, clean them off each time, and - eventually - they quit showing black.

When when rebuilding messed up trombone playing slides, if the job is done well they feel particularly good if the interiors of the outside slide tubes are polished. The trade off for doing this is having to clean those surfaces over and over until the polishing media is all gone from them.

bloke wrote: ↑Sat Nov 16, 2024 2:01 pm

Tim Jackson wrote: ↑Sat Nov 16, 2024 1:51 pm Many, many years ago, I used automobile finish rubbing compound to lap some slides. It worked nicely. You have to be able to judge when to stop, wash everything out, and see what you have. You either stop at that point or go again. What method do you use and why?

TJ

I've tried coarse and fine rubbing compound for car finishes as well as stuff sold by repair supply houses as piston lapping compound.
For pistons, rotors, and slides, I prefer Lava soap suds (created by hand), rubbed off into a bowl, and then mixed with something about the consistency of mineral oil. (I've thinned out 30-weight a bit with gasoline before. It's just as good as mineral oil.)

I’ve got rubbing compound obviously with all the cars here and I do have lava soap mineral oil etc. My question is: do you use the lava soap because it’s cheaper than rubbing compound or another reason such as less abrasive? I have a couple slides I’ve been thinking of lapping.

I think I like it because the soap suds around the pumice - from me creating the suds with my hands - seem to be a good suspension for the pumice particles.

Timesaver Yellow (for non ferrous metal)

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

DOES NOT IMBED