Can I fix this mould?

[CanoeRoller]

I have a mold that is now about 25 years old, thousands of boolits have been dropped from it. For the first time, the last time I went to use it, there is a bit of rust on it. I buffed it gently with some steel wool, and that took car of the rust. Then, when I went to cast with it. The mould was sticky, sticky to open and sticky to close. It took a great deal of force to close the mold so that boolits would not fin, and took quite a bit of force to open the mould to drop a boolit. I do not see anything that has changed in the alignment holes or pins, though some must have changed somewhere. I took the iron mold off the handles, and placed the halves together. They took a very hard squeeze to close, and a rather heavy tug to pull apart again.

Any ideas on where I ought to look to see what has happened to take great mould and turn it into a problem?

[williamwaco]

I guess alignment pins

You buffed some rust from the face of the mold into one of the alignment holes.

Next time forget the steel wool and try CLR with a que tip.

[ubetcha]

Check for a slight build up of rust in the alignment pin holes. May be causing binding

Dang! Williamwaco can type faster than me

[country gent]

With a q-tip clean the holes and pins then with a pencil eraser lightly "polish" the edges of the pin holes. You may have rolled a small slight burr into them with the buffing steel wool. Also check to insure the sprue plate isnt putting things into a bind. Although not probable check mount screws to holes to insure blocks are floating like they should. A pencil eraser will lightly polish and remove tarnish light burrs from the pins and holes quickly and easily. Look at these areas under a magnifing glass the tight areas may show up as bright spots where they are rubbing.

[runfiverun]

after a bakillion times of opening and closing molds do wear down.
I had to work one of mine over a while back, I had to re-adjust the pins and lap the cavity's, I also put a new sprue plate on it.
the vent lines were also worn down a bunch so I worked them over with a razor blade.

[masscaster]

Hi CanoeRoller,
This is from metal rolling over from the mould faces into the pin holes.
An easy fix for pins sticking is to get some Oil based lapping compound from an automotive store.
Use a cotton swab to put some compound on the pins. Now simply work the mould as if you were casting.
Open it a slight amount, then close gently. Remove all of the compound from the pins and holes with a Swab.
Repeat until the mould no longer sticks.
Be sure to use a little lube on the pins.

Jeff

[Bad Andy]

Lock Tite Naval Jelly takes surface rust off really well, put it on and let soak for no more than 10 min and wipe/rinse off with water then dry and oil it well if putting it back in stoage.

[Maven]

CR, You may want to check the protrusion of the alignment pins with a caliper and then adjust, if necessary to make them equal. A minor chamfer of the holes where those pins fit may also help with opening & closing the mold. Check each mold face for flatness: burrs, especially near the cavity: alloy: metal that doesn't belong.

[detox]

Lightly chamfer alignment pin holes with brass case chamfering tool.