Case Trimming Problems

[GregLaROCHE]

Today I started trimming down a dozen or so .45/70 Starline cases that needed to be done. Several of them developed what I would call a chatter. There was a deeper cut on part of the circumference. They made a sound of tap with each revolution of the handle. I was using a Lyman manual case trimmer. I just bought it maybe two years ago to replace an ancient RCBS trimmer I had. I don’t think I trimmed 500 cases with it. It can’t be dull. I figure I was a little too aggressive and applied too much force. I tried to clean up those cases, but I couldn’t. They just kept skipping at the bad part. I figure they’re good enough for plinking rounds, but still don’t like things that aren’t right.

[country gent]

Greg, How does the pilot fit in the case? some pilots are sized for formed brass some for sized brass. Chatter in a case trimmer is most like from a loose fit on the pilot. Another might be a to sharp of a cutter or improper geometry on the cutter. The cutter angles to cut brass are closer to carbide than steel. These shallow angles help stop the grab and pull in in the softer material. WHile the steeper angles make a sharper feeling cutter they also allow the grab and pull.

[ReloaderFred]

My guess would be the pilot not fitting correctly, and possibly too much pressure. Check the fit, as country gent suggests, and also apply a small amount of case lube to either the pilot or the inside of the case, making sure there's some on the case mouth to act as a cutting agent.

Hope this helps.

Fred

[jmorris]

There is a fellow selling LE Wilson trimmers for $25 and the holders for $5 here.

https://www.thehighroad.org/index.php?threads/wts-l-e-wilson-case-trimmers-25-and-case-holders-5-in-michigan-detroit-area.875630/#post-11672266

I bought two from him and 3 holders, got them in a few days. You won’t find a better deal on a great trimmer.

Using the case holder, you don’t need a pilot with them.

[toallmy]

Brass galling on the pilot gives me a problem occasionally making it grabby but chatter on the mouth of the case sounds like a dull cutter .

[MostlyLeverGuns]

I use a chunk of parafin to lube my brass cutting tools, trimmers, pilots, primer pocket uniformers, flash hole reamers. The hard parafin does not migrate but does smooth cutting and prevents grab. I just wipe the chunk against the cutting edge or pilot.

[GregLaROCHE]

Brass galling on the pilot gives me a problem occasionally making it grabby but chatter on the mouth of the case sounds like a dull cutter .

The trimmer is almost new. One of the reasons I replaced my old one, was because it was dull.

[GregLaROCHE]

Thanks for all the ideas. I’ll try them when I have more brass to trim.

[BK7saum]

Take a file and knock down the high spot.

This has happened to my by being too aggressive and pushing the cutter in too hard. Most time I can get it to cut out the chatter by turning fast with very light pressure.

[EDG]

Any even numbered set of cutting edges will produce chatter if turned too fast because each cutting edge can bounce into the divot caused by the previous cutting edges. In manufacturing they often use odd numbers of flutes with irregular spacing of the cutting edges to eliminate the harmonics that cause chatter to start. To avoid chatter with the .45-70 turn the cutter slower with a heavier feed rate. Once chatter starts it tends to reinforce itself with a really sharp 4 flute cutter. A dull cutter has less tendency to chatter when end cutting.

[Bazoo]

When my Lyman trimmer does that I give it a couple turns backwards and it helps. I also will reset the case in the holder and that helps cause it cuts slightly out of square. I have a new carbide cutter on mine.

[MGySgt]

Deburr/champher inside and outside the case next and try again. Normally that stops it for me