Avoiding overtightening lube pressure plug on Lyman Lube and sizers

[gunnerasch0]

About 30 years ago, to my intense shame and frustration, I managed to overtightened the pressure plug on my Lyman Lube and sizer which ruined the screw. No problem I thought as I dug out my tap and die set only to find it wasn't a standard threads per inch.
I ordered a new screw from Lyman and after a month or so was able to resume lube and sizing resolving to be more careful in future.

So more recently took my lube and sizer apart to clean out old lube. Somebody told me that savvy casters put a 1/2 inch piece of PVC
pipe over the screw to slide down bottom so that if the screw is overtightened then the pvc will break before the screw or cast iron.

Does this work?
What size PVC pipe?

Larry Murray

[snuffy]

Which one? 45, 450, 4500? On the 450, the pressure screw and piston will bottom out when the lube is gone. Further tightening would strip the threads either inside the piston or the screw threads. Putting something on the screw to prevent the piston from bottoming out will only prevent the lube cavity from getting completely empty.

Better bet is to simply be careful, and remember how long ago you replenished the the lube.

[Ed_Shot]

I got a Lyman pressure piston/screw rebuild kit for my 450 and it came with a plastic sleeve that prevents the piston from bottoming out, however, I remain sensitive to the pressure required to turn the handle. Am inch long piece of PVC in the bottom reservoir sounds like a good idea too. Over 40 years ago I broke the screw in this same 450 when I tried Lyman ALOX lube when it first came out....toooo stiff.... never did that again.