[ZipSnipe]

Ok here's my project for an air rifle I have. The c02 valve currently has a delrin plastic rear seal that the hammer pin slides thru. I want to replace that with aluminum. The hammer pin is .107 I have a .1085 drill bit for the aluminum.
The c02 pretty much freezes everything in its path. How much shrinkage am I looking at?

The reason I want to replace is the delrin is about .111 and I want to reduce how much c02 escapes out the back thus giving us a lil more uuumph in the shot

[txcncman]

Expansion will vary slightly by grade and prior treatment. The average is 12.3 microinches per inch per degree Fahrenheit. Just do the math.

[underthetire]

I just got out of the pool !

[ZipSnipe]

Uummm I thought expansion occurs when metals get heated? Also where would the starting point in Fahrenheit?

I guess I need to look up the stable temperature of the metal ?


And good for you underthetire now get your ass in the shop and back to work!! What ya think ur in the Olympics?

[keebler303]

Zipsnipe

Say you have a piece of aluminum and you measure it at 70 degrees and it is 1.000000" long. If you measure it again at 71 degrees, it will be 12.3 microinches longer (1.0000123"). If you measure it again at 69 degrees, it will be 12.3 microinches shorter (0.9999887").

A 2" bar will change 24.6 microinches per degree
A 1/2" bar will change 6.15 microinches per degree

Clear things up at all?
Matt

[uli12us]

Not really, if you measure it with a steel micrometer, who have roundabout the half of heatshrinkage you get only the half of the "desired" value.