Thanks for your suggestions! I am "compound challenged" and need all the input possible. I will say that originally I lapped the removable part of the valve using figure eight motion on plate glass and installed it in the motor after cleaning the part. The valve still leaked a lot of steam. I failed to see how I could reduce the uneven machining ridges without some sort of mini milling machine. I thought of using a Dremel with stone, but figured any hand guided attempts to smooth out the high spots would be prone to failure due to hand shake, lack of precise control, or the stone catching and jumping across the surface leaving divots no crowd of volunteers could stomp back into position. That is when someone suggested simply lapping the two surfaces using grit and air for short periods of time until the leak was acceptable.
Regarding the need for some machined grooves to carry steam oil . . . My observation is that steam with steam oil seeps all over the motor because the springs holding the oscillating valves are weak enough to ensure steam pressure and motion combined promote some leakage with lubricant. The pistons seem to be pretty smooth as well as the cylinders. No rings for these pistons. Next time I will use emery paper, probably tacked to plate glass with some spray adhesive to help it not to wrinkle or curve up and round off parts. So, would spray temporary sticky film be ok for helping emery paper lay flat? ~ Gary - Steaming over Terror Trestle http://community.webshots.com/user/raltzenthor http://www.angelfire.com/or/trainguy/ Subject: [SSLiveSteam] Valve grinding compound At 11:41 AM 9/26/05 -0700, you wrote: >Yes, I used the finest grit auto supply stores offered for valve grinding >car valves. I can imagine your shocked tone of voice in your typing. Gary, Hmm . . . well I tried not to sound too shocked. (The crackling noise you heard in the background was just me . . . being defibrilated.) What I didn't want to do was jump to conclusions because "lapping compound" could have been anything, every ultra-micro-diamond compound, so I had to ask first. I'm surprised you had any success with such a coarse grit although as Geoff points out, it worked and further demonstrates how forgiving a steam engine can bem but I wanted to suggest more appropriate alternatives. A much better and more convenient choice would be emery paper, say a 600 grit or. The valve shouldn't be lapped into the cylinder or vice versa, especially brass or bronze parts. Lay the emery paper on a dead flat surface, a piece of plate glass will do, and stroke the valve and/or cylinder across this. [News Flash - Mike Chaney's post has just now appeared and his instructions are highly recommended.] Also, most Aster kit instruction booklets have excellent explanations of how to do a two-stage emery paper lap and this information should probably be spread around as a guideline arouind which people might work. (A two-stage lap might not always be necessary.) Although automotive lapping compounds (like Clover Brand) can be had in ultra-fine (1200gr) you usually can't find that grit off-the-shelf and then only in 1/4 & 1lb tins, enough to last the entirety of the garden rwy live steam world the rest of its life! The Clover automotive valve grinding "sets" (two connected tins) usually have half-60gr and half-260gr (at best) which hardly qualify it as a "lapping" compounds in the usual sense of the word. Much too coarse. On the other hand, high quality emery papers of at least up to 2000gr can be had in individual sheets at almost any decent auto paint & body supply (Sherwin-Williams, PPG, etc). I hope this is of some use. Regards, Harry Wade Nashville Tennessee _______________________________________________ SSLiveSteam mailing list Send messages: [email protected] Cancel subscription: http://postfix.45mm.com/mailman/listinfo/sslivesteam Rules: http://www.45mm.com/sslivesteam_guide.html _______________________________________________ SSLiveSteam mailing list Send messages: [email protected] Cancel subscription: http://postfix.45mm.com/mailman/listinfo/sslivesteam Rules: http://www.45mm.com/sslivesteam_guide.html
