Mold hard to close

[Ringer]

I put a new RCBS .378-312BPS mold into service yesterday. I first treated the sprue plate and line up pins and holes with Brownells Action Magic, as I have treated other molds. When I assembled the mold to a new set of RCBS handles, which were crudely finished, with burrs in the pivot area, the mold would only close all the way by squeezing the handles to the point where the handles flex.
Both the line up pins and the correesponding holes measure the same diameter with my Dial Caliper. Cleaning the mold again with Brakekleen hasn't helped the fit. I can see no buildup of any kind on the area. Ideas, Comments ?
Thanks, Ringer:oops:

[Char-Gar]

First of all, remove the blocks from the handles and see if the handles close freely. Sometimes the nut on RCBS handles is too tight and that can make them hard to close.

If the handles open and close freely, then look at the blocks, holding them up to the light to see if you can see any light between them when held together. If you can there is a high spot or burr that needs to be removed.

If all of that doesn't cure your problem, I would guess that one of the alighment pins in the block is too far out. Find out which one it is and set it back into the blocks a smidge.

[XBT]

I think Charger’s advice will solve your problem, but I thought of one more thing. Run the mold almost closed, but open enough that each side of the mold is free to move. Then turn each side to make sure that they have enough freedom of movement to line up properly. I have seen a poor fit between the blocks and the handles cause similar problems.

[44man]

XBT most likely has the right answer. Part of the inner portion of the handles is touching the blocks. Put that part of each handle on the grinder and remove some metal.

[montana_charlie]

I think the handles you describe as 'crudely made' is where your answer lies.
Are the jaws parallel, looking from the side - not the top?
Are the mould screw holes equal distance from the pivot bolt?

If the handles are holding the mould halves slightly out of alignment, and you are squeezing hard enough to flex the handles, that mould is being stressed in ways it never expected...
CM

[Ringer]

Thanks, helpful ideas-Not the handles, at least I dont think so. I had them apart, stoned mating surfaces smooth, lubed and reassembled,blocks are free on the handles, and holes are equidistant. Mold faces won't close all the way out of the handles. One pin protrudes about .004 more than the other. Are these press fit?
Thanks, Ringer

[beagle]

Now, this will sound crude and I shuddered the first time I saw it done but there is a way to adjust the tension on RCBS handles.

Petey would take a set and place them on an anvil. He'd hit the pivot bolt lightly with a ball peen hammer. If they were loose, he's hit the bolt head. If tight, he'd hit the nut side.

Now, I know I'll get all kinds of comments on this but it works.

Other than handles, the holes in the handles are often missaligned just a bit in drilling causing binding for the first 25 or so casts but that loosens up. Occasioanlly, there are burs on the milled slots that accept the handles but this can be taken iout with a flat file.

If the blocks fit together nicely, you shouldn't have a problem other than mentioned above./beagle

[Ringer]

Looks like Chargar had the right idea. Before I took the hammer to the blocks, I called RCBS, so as not to mess up my warranty. Guess what? They said use a hammer. They call it break-in. After this didn't bring sucess, I took a hammer and a brass drift,pin and tapped on the alinement pins. First go round I could feel the pins move slightly. Reassemble-perfect fit. Hope the casting goes as well later.
Thnks again to all who offered help. Ringer

[44man]

BREAK IN! It should not have left the factory with pins out too far.

[Ringer]

My thoughts exactly,Ringer

[Jon K]

This is typical of RCBS molds in the last year or 2, I have had to work on a few before they became useable. That's what happens when production rate goes up,QC slips downhill.
When you are going to buy, if you have a chance to look first, open the sprue plate, holding the blocks closed, and look for daylight between the halves. If you make sure everything is well fitted before using, it saves a lot of frustration.

Jon
:castmine:

[Buckshot]

.............Ringer, now that you have driven in an alignment pin, and before mounting the blocks to the handles, test them. Pinch the blocks together and then try to twist them back and forth. If they move relative to each other it's no bueno por ca-ca. Or words to that effect. :-)

..............Buckshot