21st century lathe setup question

[Linko]

The first photo shows one side of the shoulder and the second the opposite side.


I have a new 21st century neck turning Lathe that I am setting up.

My cut on the shoulder is uneven. Could somepne tell me how to correct this.

Also the instructions don't discuss the cutting tool assembly alignment screw. Is it just snug?

 

[Medic505]

What caliber? Do you have the right cutter installed? How many .001's was your cut? What lube? What was your power supply and rpm?

Inquiring minds want to know..... FWIW I cut 100 pieces of new brass this morning with mine and it worked great.

 

[Linko]

What caliber? Do you have the right cutter installed? How many .001's was your cut? What lube? What was your power supply and rpm?

Inquiring minds want to know..... FWIW I cut 100 pieces of new brass this morning with mine and it worked great.

I will start by saying I never turned a neck before.

This is 308 Lapua Palma small primer.
I purchased the 21st century lathe setup for this caliber.
I am using imperial wax
Using a battery drill running as slow as possible

 

[ckaberna]

Moving the brass too fast or too much removal at one time? How much are you taking off with one pass?

 

[BP1]

Never seen that with mine.

 

[Linko]

I first cut .001 then .002

 

[SG4247]

Set up the mandrel depth first with the cutter retracted slightly using a dummy case that fits the mandrel just snug, and has the length trimmed to the desired case OAL. Adjust the manderel in or out until the cutter just gets close to the shoulder junction on the case and then lock the mandrel down.

The cutter depth should be adjustable, by just turning the dial. Start with a real light skim cut and watch that your mandrel stops the case, just before you cut into the shoulder. Adjust mandrel depth as needed, so the cutter stops the neck at exactly the right place.

Make a small cutter depth adjustment like .001” and then make another cut across the neck.

Repeat the cutter adjustment, until you get the wall thickness you desire.

Dont feed the case neck in too fast, or you will get threads!

Dont try and cut too much depth off the neck or you will chip the cutting tool!

 

[SG4247]

Couple of notes on turning with this lathe for best results.

1. Brass Neck ID must be snug on the mandrel. Neck size with a bushing if needed.
2. I trim the brass lengths before turning on the lathe within .002”.
3. I use 30w motor oil as cutting fluid, since its cheap and helps with wear on the mandrel.
4. If you chip the cutter, it will leave an uneven cut on the neck.
5. My drill tool is variable speed 0-500 rpm. 400 rpm works very well.
6. I dont cut into the shoulder taper, just up to the junction where the radius to the shoulder begins.

 

[Linko]

Set up the mandrel depth first with the cutter retracted slightly using a dummy case that fits the mandrel just snug, and has the length trimmed to the desired case OAL. Adjust the manderel in or out until the cutter just gets close to the shoulder junction on the case and then lock the mandrel down.

The cutter depth should be adjustable, by just turning the dial. Start with a real light skim cut and watch that your mandrel stops the case, just before you cut into the shoulder. Adjust mandrel depth as needed, so the cutter stops the neck at exactly the right place.

Make a small cutter depth adjustment like .001” and then make another cut across the neck.

Repeat the cutter adjustment, until you get the wall thickness you desire.

Dont feed the case neck in too fast, or you will get threads!

Dont try and cut too much depth off the neck or you will chip the cutting tool!

I set the cutting depth at .0005
Ran the rpm as slow as possible and the same with the feed rate. (No threads)
Still getting the same uneven shoulder cut.

 

[Linko]

What is the correct adjustment on the hex screw in this photo .

 

[SG4247]

Either the mandrel is loose.
Or
Cutter is loose.
Or
Neck is loose on the mandrel.
Or
Cutter is chipped.

 

[BP1]

The isso lubricant and cleaner works well also.

 

[mikeeg02]

Could be an irregularity in the neck. Only one case did that?

Also, I always run the trimmer up and down the neck twice. The first cuts most of it. The second pass makes them consistent. If you measure 5 cases with single pass cuts, you will see a difference in thickness. The second pass before adjusting definitely makes things more consistent.

I learned this after my first 100 cases

 

[SG4247]

That hex orients the cutter.

Too tight and it wont adjust with the dial.

Too loose and it may chatter.

Just snug should work.

 

[Bob L.]

Do you see any variation in the neck wall thickness that corresponds to the variation in the shoulder cut?
I also have to say that, using the 21st Century lathe, I have seen the same thing in some of the 6BRX brass I have turned. I attributed that to some existing variation in shoulder profile or thickness and used the brass anyway. It didn't seem to affect accuracy in my mid range F Open rifle. In fact, in the past few weeks, I have shot personal records using it.
I would load some up and give it a try.

 

[Linko]

Do you see any variation in the neck wall thickness that corresponds to the variation in the shoulder cut?
I also have to say that, using the 21st Century lathe, I have seen the same thing in some of the 6BRX brass I have turned. I attributed that to some existing variation in shoulder profile or thickness and used the brass anyway. It didn't seem to affect accuracy in my mid range F Open rifle. In fact, in the past few weeks, I have shot personal records using it.
I would load some up and give it a try.

I have tried 20 cases and all the same. I don't know if there is variation in shoulder thickness.

 

[Dos XX]

Is the cutter head loose enough to wobble some? Not the cutter blade, the whole cutter head assembly where it attaches to the lathe. It is the bolt in that curved slot. It should have a rubber washer on it, too.

 

[Linko]

Is the cutter head loose enough to wobble some? Not the cutter blade, the whole cutter head assembly where it attaches to the lathe. It is the bolt in that curved slot. It should have a rubber washer on it, too.

I have it snug but not tight. I just backed it off more and tried to recut a case. No change

 

[Dos XX]

Can you wiggle it in the slot by hand?

 

[ClassCat]

Is the case locked into the turner and spinning consentrically ?