Lee mold manufacturing

[stubshaft]

Does anyone know when LEE changed their production method of making moulds? I have been using them from the 1970's and at that time they made a hardened steel mold (copy of the bullet desired). Then mounted the mould halves in a press and clamped them onto the bullet mold, producing the finished mould. I have over 25 LEE moulds and just never took the time or realized that they had gone to a lathe bored system.

[pdawg_shooter]

News to me, I thought they always bored them!

[stubshaft]

I may have been mistaken. But I seem to remember an old pamphlet from Lee showing this process. The groove pattern in their RB molds indicates that they could not have been lathe bored as an assy. If they were bored they would have to have beeen cut in seperate assy's or halves or if a cherry was used it would have been in one half of the mold at a time (grooves run parallel to the sprue hole).

[Ranch Dog]

They have been bored for at least 10 or so years. Couldn't tell you before that.

[mooman76]

You wouldn't be thinking of Lyman would you? The pictures in the Lyman load manual. I have some old lee moulds and as far as I know they have always been aluminum and lath cut.

[Bent Ramrod]

I heard that the Lee roundball moulds were made by swaging the aluminum blocks around a hardened ball. The grooved moulds for regular boolits, as far as I remember, were all CNC-cut.

[Willbird]

I have some Lee Molds that are over 35 years old, and the cavities have chatter marks in them from being cut. I could not imagine they would bother using a steel mandrel that had chatter marks on it anyway.

[stubshaft]

Maybe I was thinking about the roundball mould. Thanks for the responses.

Stub

[theperfessor]

IIRC Lee used to use a advertise that their molds were formed around a hard mandrel to obtain final shape and size.

I imagine that the cavities would be bored/drilled/milled to a fairly close size before forming the cavities. I just don't think you can make aluminum flow that much and the more metal you have to move around the more wear and tear on the die/mandrel.

[hdugan]

I just don't think you can make aluminum flow that much

http://www.metacafe.com/watch/yt-qAgSU6BCpsY/making_a_scuba_tank/

[longbow]

The Lee site says the moulds are lathe bored.

I think the perfessor has it right though at least from what I remember when Lee moulds were first on the market.

I recall Lee adds from many years ago saying they machined the cavities slightly undersized then pressed them around a polished steel form of the bullet to finish the cavity.

They may have been cherry cut in those days and it was certainly before the very accurate CNC machines we have now so they may not be doing that now.

A question to Lee would surely get definitive answer.

Longbow

[Echo]

I remember Lee advertising that they used a process called 'hobbing' for their RB molds, which is what the Perfesser indicated. They would machine the mold close, then mush a round ball in for the final step. I don't remember them saying they used this process for their boolit molds...

[Cap'n Morgan]

If you look at the pics in the "Lee quality control" thread, it's obvious the cavities in the 356-120TC are milled. The longitudinal chatter marks can only come from a full-profile cutter - and probably a new-ground one, as they are more prone to chatter.

The 312-185 is another matter. The burr between the nose and the front band indicates the cavity has been cut with two different cherries, one for the nose and one for the grooves, and, judging from the smear on the surface, the cherries were far from new.

All in all I don't think the molds are too bad. How Lee can produce them at the price they do and still make a profit is beyond me.