Piston Lapping

[rick41]

I am building a "Flame Licker" engine and am ready to lap the piston and cylinder.  I am looking for experienced advice.  What to use for lapping compound and procedure.  I have several choices available:  Jewelers Pumice Powder, TimeSaver (4 Grades),  Toothpaste, & Fine Clover Valve Grinding Compound.  I am leaning towards the pumice or Timesaver (very fine).  Thanks in advance.
Rick

[fumopuc]

Hi Rick,
may be this will help you to find your way.
http://www.modelenginemaker.com/index.php/topic,1908.0.html

[Ramon Wilson]

Depends on the materials involved but if a combination of steel and/or cast then no hesitation - Time Saver. I don't have any nor have ever used it but if I had it it would be my first choice. It has excellent properties and breaks down into finer particles as lapping proceeds.

Just lapped three cast/steel piston/liners with silicon carbide - would have loved some Time Saver but a much too expensive an outlay with all the carborundum I have to hand 

Good luck with your project Rick

Tug

[crueby]

I have used Timesaver on most of my engines, great results, and the way it breaks down and stops grinding is very handy. You can buy sample tin packs that are enough for many models.

[Chipmaster]

I also recommend Timesaver for piston/cylinder lapping, excellent results every time. A few years ago I bought two small plastic pots green for ferrous and yellow for non ferrous. I remember doing a lot of net surfing to find a source for small quantities at reasonable price but I can't recall who I bought it from. Looks like it's sold for £22.95 for a 3oz pot on eBay at the moment.

<a href="https://www.youtube.com/watch?v=w1p7C5fhZjk" target="_blank">http://www.youtube.com/watch?v=w1p7C5fhZjk</a>

Andy

[rick41]

Thanks for the input.  I do have timesaver.  I bought a sample pack of 8 tins from McMaster Carr about 20 years ago.  Four tins for ferrous and four tins for non[ferrous.  I have used them for both steam and hit and miss with very good results.  Since this is my first vacuum engine, I was concerned about piston fit.  O=Rings can make up for a lot of mistakes with steam and combustion engines, but with vacuum engines????  By the way, I think I paid about $35 for the timesaver sampler.  It will last me until my modeling days are over.
Rick

[b.lindsey]

Pricing seems to vary a lot based in supplier, but this seems to be the best deal...4 3oz. Tins of yellow and 4 3oz. Tins of green for $59.50.

https://ws2coating.com/timesaver-lapping-compounds/

Bill

[Jo]

Personally I don't use a compound on my pistons I use an oil stone. 

For larger diameters I use my external hone that I made - see pic. For smaller ones I was going to make another external hone but find I can very easily hold a bit of stone in my fingers while honing.

Jo

[Mosey]

I have some Timesaver, 2 grades and since I'm out of machining now I'd like to find a good home for this. Just let me know if you want it.
Mosey
Tons of other stuff also.

[Jasonb]

On my "Chuky" flame licker I use a brake cylinder hone on the cylinder and then lapped the piston into that with SiC powder & oil see this thread

http://www.modelenginemaker.com/index.php/topic,7193.msg151390.html#msg151390

For the Woody after honing the bore I also gave it a quick lap on a solid aluminium tube and then sized the piston with Wet & dry on a flat stick before finally lapping it into the bore after covering the lathe bed