Lyman DC mould problem

[Shuz]

I just received a Lyman 257464DC mould that has a problem. When you hold the mould halves together and look down the cavities toward a bright light, the cavity furthest from the sprue plate screw, shows a little "daylight", the other cavity not so much. I installed 2 different sets of Lyman handles, an RCBS set and a Lee set, to see if a little pressure would eliminate the problem, but alas, it does not. I noticed that the right block, the one without the sprue plate screw, does not move easily on any of the handles, but is rather rigid. The other block swings freely as do most of my moulds.My thought WAS that the hole drilled thru that right block may not be in the correct location, preventing complete closure. BUT how does one explain that the two halves do not mate properly without the handles?

I tried twisting the halves to see if there was any pin slop and there is absolutely none! The mould surfaces also appear to be clean and free from any foreign matter.

Any suggestions on what's going on here and how to correct this problem?

The owner of this mould has given me permission to put a dimple on the nose of one cavity in order to distinguish which cavity a given boolit droppoed from. I'll take some measurements of the various diameters as cast and see what happens.

[poppy42]

Try carefully removing the alignment pins, hold both halves of the mold tightly closed and then shine a bright light to see if you see any daylight. Examine the pins closely making sure there is no bars on the pens or that they’re bent in anyway. If the pins are not damaged you might have to carefully stone the area with a fine abrasive stone or some Fine sandpaper. Just make sure you keep the mold half’s perfectly flat when stoning them.

[Tar Heel]

I once had a mold like that and was informed by the manufacturer to start casting with it. Low and behold, the halves aligned themselves after the mold got heated up. I never would have believed it had I not seen it myself. Heat them up and start casting to see if the heat aligns them.

291518 291519

[georgerkahn]

I had a similar challenge years back, and my "solution" was to remove pins and sandwich halves on a piece of window-pane glass (scrap from an old window) on which I smeared some valve grinding compound. A rubber band around ends of handles applied necessary pressure. It surprised me as it did not take all that much time, effort, or compound. When done, I used a toothbrush and a petroleum solvent -- don't recall which -- might have been white gasoline or lacquer thinner ?? -- followed by a dishwash detergent followup. I then chased the pin holes with a number drill and reinstalled. The mould worked!
geo

[Mk42gunner]

One pin may be protruding just a bit too far.

After close inspection with a magnifying glass, none of our eyes are getting any younger, I would tap the pin on that side back in a few thousandths of an inch and see if that fixes the problem.

Be advised, every Lyman alignment pin I have ever attempted to move took a pretty good tap with a three pound hammer driving the punch to get it started. I did do it with the mold cold.

Robert

[rintinglen]

One pin may be protruding just a bit too far.

After close inspection with a magnifying glass, none of our eyes are getting any younger, I would tap the pin on that side back in a few thousandths of an inch and see if that fixes the problem.

Be advised, every Lyman alignment pin I have ever attempted to move took a pretty good tap with a three pound hammer driving the punch to get it started. I did do it with the mold cold.

Robert

If I were to bet, I would put my money on what Robert has written. I also second the use of a magnifying glass to check the edges of the Alignment pin holes on BOTH sides to see if they are Peened up. I have a 4 cavity 311-419 that suffered from that malady and it took a bit of careful tapping with a ball peen hammer and some fine sand paper to get things to work right.

[Shuz]

I measured the pin protrusion and noted that there was only. 002 difference in them. I carefully sanded the area around the pins and pin holes. I then proceeded to cast a few boolits and then measured them. I could tell no significant difference between the boolit as dropped. The weight variance was in the 2/10th's of a grain area. That's good enuff for me. Now to see how they shoot. Any suggestions for the. 250 Savage and this boolit?

[rintinglen]

I tried 14.0 grains of 2400and it was "OK" but not spectacular. I keep meaning to get back to that project but I have too many other things that keep getting in the way.

[Cosmic_Charlie]

The suggestion to cast with it was a good one.

[zarrinvz24]

http://www.castpics.net/subsite2/MoldMods/LymanMoldTuneUp.pdf

I would suggest you read through this .pdf and see if it helps. My collection of Lyman molds is approaching 40 different designs. I've tuned each of them up as I get them, and I've been really surprised how well some of them can cast despite obvious flaws like light visible between the mold halves. Similar to a rifle with a pitted bore, it can still provide plenty of useable accuracy.