Threads in acrylic and chipping.

[alexkuzn]

Guys,

do you experience chipping when tapping acrylic?
My outside threads look perfect but inside threads(M8.4x0.75) have some chipping.
My threading die is adjustable so I cut threads in three passes gradually decreasing the die diameter. Taps can't be adjusted so they cut threads in a single pass. That probably puts too much stress on acrylic and causing chipping.
I use Moly-Dee tapping liquid.

Do you guys experience any chipping when tapping acrylic?

 

[ldb2000]

For acrylics and tru-stone I find that Pam butter flavored (I actually use generic A&P brand) cooking spray works great for a lubricant . Several others have tried different types of lubricants but found the cooking spray works best .