lucite/plexiglass

[Tin Falcon]

For multiple reasons have not completed n engine in a while.Long commute to work , busy at work ,trying to paint my house ......
Well today decided to start a somewhat modified version of Rudy K's "Steam Engine" Pg 100 shop wisdom 1.
I have a piece of 7/8 lucite I think ,salvaged from a shower.
Drew it upon allbre Ok no problem. drilled and reamed the cylinder bore a bit rough but have dealt with similar issues before not a BIG deal. then drilled for the valve got the bright Idea of using litle fine plastic polish for lubing the drill worked nice. then ran the reamer through was pleased with the finish . Spent way too much time trying to polish /smooth /lap the cylinder.finally decided to clean it up and call it quits for the evening. I had already used IPO to clean the glue from some tape off the outside not problem poured a bit in the cylinder and what the ?????
Looks like a piece of heat shocked glass cracks all over the place so nothin made tonight aaarg.
Tin

 

[ghart3]

Darn, hate it when that happens. Have had something like that happen to me. Drilled and tapped a bunch of small holes is some clear mystry plastic. A day or two latter there was cracks all over the place.

Done some reading and guessing that the wrong lube was used. Read petroleum based cutting fluids can cause stress cracking.

Also from reading learned too much heat from machining such as using dull drill can cause stress.

Couple good links with info on plastic machining and annealing are.
http://www.boedeker.com/fabtip.htm
http://www.boedeker.com/anneal.htm
gary