Lyman lathe case trimmer (Orange one)


March 30, 2010, 07:34 AM

We all got a good laugh (at me) yesterday in another thread. Now let's try to make fun of me again..and at the same time, resolve a little annoying predicament that I am suffering.

I already reported this issue here but I could not resolve it.

I am using a Lyman lathe case trimmer with a Dewalt drill instead of my elbow to power the trimmer. I run the drill at about 1/4 of the top speed. That means it will run 1-3 seconds max. Often, when I see material is removed, I run it more carefully so the material does not get in the way of the trimming.

I set the trimmed Case Length between 1.751-1.752 as measured with my caliper. When I chamfer and deburr, it brings the case very close to 1.750 (sometimes 1.7505 or 1.7495).

Of course, often, there are cases that are under 1.750 and the bit just runs on nothing. But I still do a little bit of chamfer/deburr just in case.

My problem now....:banghead:

I need to measure at every 5-10 cases I trim because MOST OF THE TIME the trim length shorten. Then I have to reajust the bit. At first, I simply use the "micro ring") and do a 1/8 turn. But within 200-300 cases, I need to adjust the main ring.

Sometimes, the countrary happen. I need to adjust because the length of the case gets longer. It is very rare, but it happened a few times.

I am thinking the main ring is moving on the main shaft beeing pushed when I resize and have to push in the drill on the case. I tried to put a nut with a set screw in it behind the main ring, but I could not make it work.

Hit me with your ideas now... :D

Thank you

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March 30, 2010, 08:18 AM
You might be banging the trimmer into the case instead of slowing pushing it. 200 little jolts could slide the collar maybe?

March 30, 2010, 08:22 AM
Sorry about yesterday. Are you tighting both set screws? Is your cutter head sharp so you dont have to push hard on the cutter shaft? I would turn the micro adjustment and the main adjustment tight into each other so that all adjustment is made with the 2 units as one. Then make the set screws on both tight. I think you are just pushing to hard on the cutter shaft and the cutter head is dull. Lyman sells new cutter heads. The Dewalt drill could be making Vibration, acting on the 2 set screws. Put some Loctite or nail polish on them.

March 30, 2010, 08:31 AM

Don't be sorry about yesterday. I got a good laugh at myself. My dad always said: "If you are not worth a laugh at you, you are not worth much." And trust me, I goof often.

About your questions:
- I changed the cutter head a few months ago for a new one.
- Yes, after thinking about it, I do push in and hit the cutter on the brass because I am not as careful as I should be. I will as of now be more careful and proceed slower.
- When I set up the collets, I put the micro collet half screw on the main collet. I tighten the set screw. Then I set the main collet to the best I can to get the right trim length and then I adjust a little bit the micro collet.
- The set screws don't get loose at all in both collets.

I have plenty of brass to trim, tonight I'll be more careful when I insert the bit into the case mouth not to hit each time. We'll see if that it simply that.

Thank you

March 30, 2010, 11:10 AM
I would be of the thinking that you are hitting the adjustment stop harder than the set screws are capable of holding. I would check the set screws themselves to see if the cupped ends are still good, if not replace them with good hard ones with the cupped ends. Not all set screws are made the same, there is some soft junk out there.

Jimmy K

March 31, 2010, 12:52 PM

Trimmed 200-300 yesterday. Went very carefully. Still had to adjust 2 times the main ring and many times the micro-ring....

I am positive, I did not slam in and I went slow and carefully...

Thank you

March 31, 2010, 09:11 PM
Maybe try a new set of set screws with a little removable locktite

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