SETTING UP A COLLET DIE

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  • Last Post 16 December 2023
4895 posted this 11 December 2023

I'M TRYING TO SET UP A LEE COLLET DIE, I'VE GOT A ROCK CHUCKER  PRESS AND PUZZLED

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Pentz posted this 11 December 2023

Simple.  The further the cartridge goes into the die the harder the sizing.  What is the diameter of the core rod/deprimer?  That determines the maximum squeeze.

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Glenn R. Latham posted this 11 December 2023

Evidently Lee presses don't "cam over" at the top of the stroke like most presses do.  Lee has different instructions for Lee and "non Lee" presses.  They want you to screw the die WAY down so the press can't cam over, but will stop when the collet forces the case neck against the mandrel.  I suppose this is OK if you're sizing the necks for jacketed bullets.  I just screw the die down a little at a time until I get the case neck I.D. that I'm looking for, all while running the ram to the top of the stroke.  CAUTION: don't run the shellholder up against the bottom of a collet die unless there is a case in the shellholder!  I also find they will run a little smoother if I put a little grease on the angled part of the top of the outside of the collet.

Glenn

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John Carlson posted this 12 December 2023

I use the dies as the instructions direct.  If I want more/less neck tension I use different sizes of mandrels.  You can buy them or make them.  Several use Glen's approach which apparently also works.  +1 for grease.

John Carlson. CBA Director of Military Competition.

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John Alexander posted this 12 December 2023

Glenn has it exactly right. Cut out his message and past in on your collet die box.

Lee's instructions (and a lot of other people's) will tell you that you must press the inside of the neck against the mandrel. But as Glenn says the mandrel is sized for jacketed bullets. You can make, or Lee will sell you larger mandrels -- total waste of money and steel, just back off the collet die.  Don't go wild. A few degrees of rotation of the die will change the neck diameter 0.001". 

Collet dies, used by the Latham method, make the OD of the neck uniform instead of the ID just as the expensive bushing type dies do. This is no problem with any one lot of recently manufactured brass.  Theoretically, this could be a problem if you are using a mixed lot of brass with wildly varying neck wall thickness.  However, collet dies make the brass last so much longer than conventional rifle dies that you can afford good brass.

John

 

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MP1886 posted this 12 December 2023

John, not exactly a waste of money. There are many things you can do in modifying the LLE collet dies. Aside from turning different size mandrels you can even turn a mandrel, plus modify the collet, to give you not only a sized neck to the diameter you want, but also flare the case mouth for easy cast bullet seating without shaving!!!  

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John Alexander posted this 12 December 2023

This seem like a worthwhile modification to try. I have been told that Lee is making this change before shipping.  Don't know if that's true. I believe that instructions for making that modification were first published in TFS by past CBA President Bob Sears about 15 years ago.

I don't want to be argumentative, but the change, at least as described by Sears, doesn't require a new mandrel.

John

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mashburn posted this 14 December 2023

I had a set of collet dies that gave me some trouble. I guess the collet got worn or lost it's spring temper or something. It was a .17 caliber die set. Sometimes the collet would stick closed and when you pulled the press handle down to withdraw the case, the collet would remain closed and stretch a 40 degree shoulder into and long case with out the 40 degree shoulder. That is the only collet die set that I ever had any trouble with.

Mashburn

David a. Cogburn

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Hornet posted this 14 December 2023

The actual collet portion on these dies does not seem to have a very spring temper on them. It is sometimes necessary to disassembly them and drive a tapered pin punch or a similar tool into the collet to expand it back out. Polishing the compressing taper on the collet closing sleeve and putting just a small dab of high pressure grease on the taper will help keep it from sticking in the compressed position. Doesn't need do be done often (every couple hundred cases or so) and the burnishing of the surfaces from use helps smooth them out. I have had case necks accordioned and even partially telescoped when the collet has not expanded back open. That's usually a good sign that you waited too long...

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mashburn posted this 14 December 2023

I did all of those things, basically, and it didn't solve the problem.  I gave up on them and now they set idle waiting on something to do.

Mashburn

David a. Cogburn

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4895 posted this 15 December 2023

i know how important neck tension is and having problems with the collet die i took a full size die and backed it off to just size the neck i hope my problem is solved

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Larry Gibson posted this 15 December 2023

4895 posted this 2 hours ago

 

i know how important neck tension is and having problems with the collet die i took a full size die and backed it off to just size the neck i hope my problem is solve.

Depending on the cartridge taper and amount of case expansion it probably will create another problem.  The FL die will push/size the expanded sides of the case inward.  That will push the shoulder forward causing hard chambering.  Best to just get a NS only die if you don't want to use the Lee Collet die.

LMG  

Concealment is not cover.........

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MP1886 posted this 15 December 2023

Neck sizing is pretty good, I've done it for decades.  Eventually if all you do is neck size you will have to full length resize to bring your cases back to more normal because they get tighter and tighter in the chamber. Now I haven't, so far, found this necessarily true with neck sizing with the Lee Collet dies.  

You have to maintain the collet dies like some of mentioned in here such as lubing the taper portion. Another thing you may look at is put the center section out of the die body and see if any debri is trapped in the slots cut into it. These won't let the fingers compress correctly. 

One thing Lee might have done to these collet dies is make the top cap out of steel instead of aluminum. If you have popped that aluminum cap out of the die stripping it, then you haven't messed with them as much as I have.  At least I admit I've done it. With a steel cap it would have been much harder to do. 

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Hornet posted this 15 December 2023

I believe the cap was made of aluminum to provide a cheap and easily replaceable part to act as a planned failure point for the cases where people might have become a little too exuberant in trying to tighten things up. Sometimes you have to readjust things for a change for thicker case necks. I've popped a couple of them and I usually keep a couple of spares on hand just in case. The shipping is much more than the part cost for them unless you include them on another order.

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joeb33050 posted this 16 December 2023

I'M TRYING TO SET UP A LEE COLLET DIE, I'VE GOT A ROCK CHUCKER  PRESS AND PUZZLED

I take out the mandrel, store or throw out mandrel, adjust the die to neck size properly. Deprime is first step. Worked for me with several / many ctgs. for years. Think about it, about what a collet is. The mandrel confuses a simple process.    

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MP1886 posted this 16 December 2023

My question is Joe, is the mandrel there to help shape the neck when you are squeezing it with the collet or there to have a stopping point as to not size the neck down too much.  Often fired brass had dented mouths and other irregularities from ejection from the firearm especially in semi auto ones and also from hitting objects when it lands from being ejected.  It's in my opinion that the mandrel is there for a few purposed. One would be to have the decapping pin. The other is to iron out the irregularities I spoke of with the help of the collet squeezing. The last is a stopping point in the whole sizing operation.  Here's the definition of mandrel:

a cylindrical rod around which metal or other material is forged or shaped.

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