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Re: Making A Lap!

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Posted by Robert May on August 9, 1999 03:17:14 UTC

Well, there's all kinds of testing to check for the proper viscosity of a lap but the dirty little secret is that it's mostly for an individual to test for what he likes for a lap hardness. Just pour the lap and try it out. Some people prefer to work with a hard lap and others do thier best work with a soft lap. If you have pitch from one of the mirror kit makers and it's fairly fresh (only a couple of years old at the most) then it's probably just about right for most people. Pour the lap and hot press the grooves in while it's still hot that you need and make sure that they are off-centered on the tool. Perfectly centered and square precision laps tend to have problems with zoning and rings. It's one of those times where crude workmanship in the placement of the lines is the best thing. Pressing the lap before polishing for a few minutes is usually required and is no problem if you first wet the mirror and lap in warm water. You can go fast with your strokes in the initial polishing but after you get it almost polished out, you need to slow down to about 1 stroke in 2 seconds. Out (1 thousand 1) and in (1 thousand 2) is about the right timing for figuring. I've gone a lot faster than that but the process can quickly produce a turned down edge if you're not careful. Watch and see where the polish starts and look at that area and see what it looks like compared to the other parts of the mirror and you will see the various degrees of polishing as you go. Remember that this is the first mirror of yours and you will enjoy the discovery of seeing the mirror finish up as you go along. Just be patient and enjoy the process. After you've done several mirrors then you will learn the fast ways of doing things, mostly fast as hou know how much you need to do. Start testing with the Foucault tester just as soon as you are mostly polished out and follow the results of the test in your subsequent polishing. It will help in getting you familiar with the testing of a mirror and what does what in the figuring of the mirror before you really have to learn. Also remember that zones happen from being repetitive in what you're doing. It's going to take a while for the figuring but it's a time to just settle back and watch the process happen and remember that professionals all have been where you are going to go. Have fun and don't be a stranger.

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