Lyman Sprue Problem

[BeemerMark]

I have an old Lyman 452 4 cavity mold that has worked fine for thousands of boolits. Last night every time I dropped four the pivot screw on the sprue plate would become so loose that the next pour would flash between the sprue plate and mold block. Finally ended up tightening the screww every pour. The screw is backing out two or three turns evertime I drop.

??? Help???

[oldhickory]

There should be a set screw on the side that holds the plate screw. It could have loosened allowing the plate screw to loosen. On the old Ideals it's a slotted screw, on newer molds, an Allen type. It runs at 90 degrees to the plate screw.

BTW-the Allen head set screw takes the same wrench as RCBS reloading dies. I hope that's the only problem.

[old turtle]

Some of the old Lyman set screws are no.8 screws with 36 thread which is difficult to find. The newer set screws are 32 thread.

[casterofboolits]

The old split washer used by Lyman can dig into the sprue plate and cause the pivot screw to turn. Put a thin spring steel washer under the split washer, adjust tension and lock the pivot screw with the side screw and this will help eliminate the problem.

[leadman]

I have found the holes for the lock screws for the sprue plate screw are not tapped all the way thru. They threads are tapered smaller diameter near the end so find a bottom tap and chase them out . I file the leading edge of the split lock washer for the sprue plate so it does not grab.

[CJR]

Ditto what Leadman said. I had the same problem on my Lyman moulds. I removed the lock screws, measured the thread size, re-tapped the holes and the problem went away. Now when I tighten the lock screws, they stay tightened and the sprue plate screw doesn't back out/loosen up.

Best regards,

CJR

[runfiverun]

iv'e had to lightly file the burr off the sprue plate before.
and adding a piece of shot has helped with the set screw on occasion.
i had a stop screw for the sprue plate come loose annoyingly before and had to lock-tite it in place.

[Grapeshot]

My spru plate screws come loose all the time. I decided to take out the set screw and using a small diameter awl I scratched the screw thru the set screw hole. When I took out the spru plate screw I filed a flat spot where the scratches were and replaced all the screws. Now the spru plate screw does not move as the set screw is butted up against the flat spot on the spru plate screw.

[94Doug]

Grapeshot's method was written up in Handloader some time ago.....I believe they filed a mark on the screw head at the location of the setscrew for reference on where to file the flat spot.


Doug

[old turtle]

Good idea to replace the old lock washer with a wave washer and a flat washer. 6MM washers work well. Good luck.