Lyman Case trimmer question..

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calvin5673

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Hey,

Got a used lyman universal case trimmer. It looks like its seen some use/probably a little abuse.

When I go to change the trim length I noticed the coarse and fine adjustment are both real sticky/ hard to turn. So i took it apart and noticed that the set screws have pushed nylon at the bottom of the set screw hole out of place and it now jams the fine adj. threads or catches on the rod (coarse adj.).

Could I carefully drill these holes out so that the set screw bears directly on the fine adj. threads/rod, or will that just damaged the fine adj. threads.

Any thoughts would be appreciated. Let me know if I'm not making sense.

Calvin
 
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I have had my Lyman case trimmer since the mid 1970s, I replaced the set screws and replaced the cutter with the upgrade carbide unit.

The trim adjustment knobs are just like die lock rings with a set screw and can make adjustments hard to make.

When I replaced the set screws with a better design the adjustments became easier.

Bottom line, the adjustment knobs were always hard to break free and make adjustments. For the same reason why many people change the lock rings on their dies to the split ring type.
 
I would not drill out the set screw holes as I would not want to risk boogering up the threads in the holes.

I assume that you have the Lyman trimmer disassembled. Carefully run the set screws all the way through the holes to try to get those threads clear. Run the set screws right through so that they fall out of the bottom of the holes.

Then smooth away the burrs at the bottom of the set screw holes with a needle file if you have one and some fine grit wet/dry sandpaper. File and sand gently and carefully to make sure you're just getting the burrs and are not cutting a groove and making the ring out of round.

Sanding and filing may push metal back into the holes. You may need to run the set screws through the holes again to push things out and then file or sand again.

When you get the holes cleaned up, put things back together.

Put some lead shot into the set screw holes. I put a few pellets of #7 or #8 target shot in mine as soon as I got mine. Secure the set screws down on the lead shot.

The shot will deform and you can tighten down the set screw without damaging the fine threads.

I do the lead shot-in-the-set-screw-hole trick for any mechanism that has a set screw bearing down on threads.

Hope this helps. Good luck with your fix.
 
What seems to help when trying to readjust the adjustment settings is back off the set screws a couple of turns and the give the adjuster ring a hard wack with a good screwdriver handle (or two) that seems to displace the nylon ball back into the screw knob enough to allow free movement of the adjuster. I had the same problem with my Lyman case trimmer and this works most of the time.

the nylon ball will get flattened out after a while and will need to be replace every once and a while.
 
calvin5673 said:
What did you use as a replacement set screw? I'll be upfront my knowledge with set screws is not very advanced.
Click to expand...

My original hex head socket set screws were enlarged/stripped and could not be tightened correctly. I went to the hardware store and bought longer set screws and new allen wrenches that fit properly. I also made sure the set screws were cupped shaped on the bottom to grip the shaft.

All I can say after doing much of what MDF stated above and replacing the set screws with longer ones my adjustments became easier. This may have just been the ability to see the top of the set screw better and making sure the allen wrench was pushed deeply into the set screw. But the longer set screws helped a good bit and less tightening effort was needed to stop any slipping.
 
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