Lost some out of roundness .....

[Jack Stanley]

I've been fooling with a used mold I bought , it had a bit of out of round the sizer wasn't cleaning up and left a small flat where the sizer wasn't really getting . Down in the dungeon with it tonight I was taking a break from other things and got to looking at the ogive of a sized bullet . I ran my fingernail over it and found a very slight step or catch that I thought was a misalignment of the halves .

So just looking for answers to the round problem i wondered if the locating pins were snug enough . Taking the blocks off the handles and trying to turn the halves opposite directions show some movement . Hmmmm I thought I knew they were better than that last time I used this . So , I got out the brass punch and bumped them into the other block even more . I went to far on one and it made the blocks sticky on opening so I had to bump it back and try again .

After several minutes of trial and error I got the blocks so there was no "chucking " when I tried to rotate the blocks . And , there was no sticking when I opened them .

Casting with them showed an improvement with the little "step" on the ojive almost gone . Measuring with a one inch micrometer showed it was better and checking when they came out of the size die was visably better .

Maybe tomorrow I can fool with it a little more and see if I can get it better .

Jack

[geargnasher]

I have four Lyman POS single-cavity moulds that have the cavities cut with the halves shifted somehow and results in about .003" misalignment although the outside of the blocks aligns perfectly and the pins are correctly seating. I have made some offset pins for some of them, but it's difficult to get them just right. One of the many reasons they don't get my business anymore.

Gear

[Jack Stanley]

Gear , I'm just barely competent with my micrometer and a caliper so I couldn't really tell you how much misalignment I have with this one . Someone else has used it quite a bit so I can't say how much is wear or lack of adjustment either . In a case like your molds there is no excuse for quality control to let that out the door ..... I'm starting to wonder if Lyman is becoming the LEE mold of the iron mold makers . No offense intended to LEE , I understand they are trying to clean up their act .

Jack

[a.squibload]

Jack:

Good job Mold Technician!

I had similar alignment pin problem on a Lyman 429421, 2C, got it recently on the Swap & Sell forum.
Without handles I could rotate the halves slightly around one alignment pin.
Probably why it was for sale.
Did same as you, adjusted the other pin in & out 'til it fit better.

There's a thread or 2 here about stippling the pins for tighter fit, might help to keep it in place
once you find a good adjustment.

Basically remove pin, squeeze with vice grips, or otherwise deform pin surface for tighter fit,
tap back in hole.

[Jack Stanley]

Thank you sir !! I'm pleased I was able to get this far with it without resorting to the five pound drilling hammer I keep in the other room for "difficult" molds .

After making the last adjustment on it and pouring about a hundred casts or so I let the mold cool down and checked it again last night . It had a very slight rattle on one of the pins so I thought I'd try to measure the amount I was moving it .

I set the mold half with the pins on a nylon bench block after measuring with a caliper . The caliper jaws went across both flats of the block rather than in the handle groove . This time , the energy to tap the punch was from a small brass hammer against the brass punch instead of the lead hammer I normally use . I was able to move the pin four thousanths and that cleaned up the rattle .

Now the question I have to answer is , did my use the last time move the pin back or did the pin just wear over a burr or something that was in the hole . I'm very carefull to line the mold halves up before closing so this will be interesting for me to find out . Now they are cool from last nights casting I think I'll go check them out .

Jack

[Jack Stanley]

I went back and checked the length again and the pins hadn't moved . So , with time to work on it today I tapped it out another ten thousanths . The mold was quite sticky trying to open them without the handles but with the handles on and warm I didn't notice them sticking at all .

I pulled a page out of someone elses play book and tried to lap the cavities a little . Both cavities were pretty much equal in measurments and both had a spot where as cast diameter went down to .451" . Even after sizing this "flat" spot was there and I think is contributing to leading in the pistol .

So , I dug around in the sprue box and found a couple wrinkled and nasty looking rejects and drilled a hole in the base . A self tapping screw was turned in tight and a file was used to make a flat on four sides of the bullet . The mold was closed on that to see if I could wiggle the bullet back and forth and more was filed off the bullet untill it would . Then a little LBT bore lap paste was put on two of the flats and the mold closed on it and clamped with a padded bar clamp . I used a nut driver to twist the screw untill it would turn all the way around then turned it several times untill the cutting felt slowed . Several times I stopped and opened the mold and wiped any residue that got between the blocks before continuing .

Both cavities were done and I'd guess each took about twenty minutes to do . When I thought I'd done enough damage I used a "Q-tip" and laquer thinner to wash the grit out and Kroil after that then wiped dry . The "flat" spot was mostly gone and where it was measured .4525" , odd thing is the rest of the mold didn't really change all that much . It started at .4555" and it isn't much different now , just that it's better polished now . The parting line on the mold is now almost invisible compared to where it was . Bullets come out of the mold with almost no persuasion at all now and weigh in at two hundred twenty-four grains .

I sized and lubed twenty bullets , they were nice and round with no flat spot like the others . So , I loaded them over a charge of five point three grains of SMP-231 hopefully tomorrow I can try them and see if my leading problem has gone away .

Jack

[MtGun44]

A little bit of well thought out hand fitting and lapping can many times improve
certain types of precision machinery. Sounds like you are really tuning up that
mold. I'll bet the boolits will work better.

Bill

[Jack Stanley]

I intend to try them after lunch today . The goal is to have a hardball like load that doesn't lead the barrel using this Lyman version of round nose .

Jack