Loose mold alignment pin

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Last Post 26 June 2020

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John Alexander posted this 23 June 2020

Just discovered that one of the three alignment pins on my most used mold had backed back into its hole and wasn't engaging the alignment hole in the other block when the blocks were closed. When examined, I discovered that I could push the pin in and out with finger pressure -- just the opposite of some of my mold where the pins seem immovable.

After casting a few bullets it had backed out of contact again.

What is the best way to tighten things up so the pin will do its share. The other two pins are doing about the same job that three did earlier (.001" misalignment of blocks.)

I thought a bit of judicious peening should work and I might be able to improve the block alignment but nervous about monkeying with the block faces.

Suggestions?

John

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Bud Hyett posted this 23 June 2020

Peening will work, but will soon wear and you are back to the same condition. The ideal solution is reaming the hole and using a new pin, possible two step diameter, one to fit the over-sized hole and one step to fit the original align hole. By the time you do this, you have the cost of a new mold,

You need to be able to set the pin and glue it. A high temperature glue on the outside will work. If the pin is recessed enough to be able to simply add the glue within the hole, you are in good shape. When the glue wears out, you can redo it without changing the dimensions.

Be very patient in doing this.

Farm boy from Illinois, living in the magical Pacific Northwest

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RicinYakima posted this 23 June 2020

An alternative to "glue" would be a Loc-tite "bearing retainer" fluid. They have several kinds, and you need the high temperature stuff. #620 is preferred but #290 may work. The pin has to be adjusted exactly right and cleaned spotlessly but will work. Stuff isn't cheap, but about the best there is, so you may just have to beg for help from a machine shop. HTH, Ric

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billwnr posted this 24 June 2020

send it back to the mfgr for rebuild.

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Boschloper posted this 24 June 2020

A trick that I have used on manufacturing tooling is to take a ball bearing (just the ball) that is 3 to 4 times the diameter of the hole, lay it over the the hole and hit it with a hammer. This peens the perimeter of the hole in very uniformly. I have done this meany times with good success. I keep a 15mm ball in my desk at work and another on my bench here at home. Good luck.

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ray h posted this 24 June 2020

John would it be possible to roll the pin between a hard surface and a sharp fine tooth file, trying to raise a fine knurling on the pin. Not sure how hard the pins are, it may not take the knurling if hard.

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Bud Hyett posted this 24 June 2020

When I saw John's question today, I thought of my mold reclaim project for today. I offer this as a similar situation and how it was solved.

Today's Project; reclaim a NOE brass four-cavity mold. The bullets are .002+ out-of-round and the tow inner cavities have fins varying in size with each fill. When you close the empty mold and hold to the light, there is strong light shining through. I am not sure how this happened, my thought is the usage caused warping or it was dropped.

First step: Try different handles. RCBS, NOE and Lee were tried with the exact same result. The handles are not the problem.

Second step: Clean the faces. There is trace lead at the bottom of the two inner cavities. Heat and bronze wool, scrub along the vent lines. No change, the light coming through does not lessen. When held to the light, the sunlight came streaming through.

Third step: Check inner faces for flatness. Not having a surface table, I set them in a vise and used a (new) flat file to dress the surface. There was a few high spots on the first and second pass. However, on the third stroke the mold surface was slightly touched across the face on both inner surfaces. I moved the alignment pins back flush with their surface such that the file had a clean sweep across the surface. This time, the sunlight was blocked across the entire mold. Major change.

Fourth step: Reset the alignment pins. The mold was set on an inch-thick brass piece to allow structured hammering. (I have done this before with iron molds and a person can hear a different tone when the alignment pin first hits the alignment hole.) First I marked the alignment holes with a red Sharpie to have witness marks and see the contact points as the pins moved forward. Next, the pins were driven with medium hammer blows to see how far the pins would move. After eighteen blows, the pins went in the alignment holes, the witness marks showed they were even. And these blows sounded different.

Fifth step: Use the mold. The mold was back to its flawless behavior; no fins, out-of-roundness within .001. bullets drop easily from the mold. The alignment pins are tight, there should be no movement. However, I will check this mold each time it is used for alignment and pin migration either forward or backward.

Farm boy from Illinois, living in the magical Pacific Northwest

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Tom G posted this 24 June 2020

John, One thing you might try is to make the pin a little larger by peening it with a prick punch.

Take it out and lay it in a vee block so that it is backed up. Take a prick punch and grind it to a nice sharp point. Then peen some small dimples onto the pin to raise some welts on it. Try to get the peen marks the same all the way around it like in 4 lines end to end. This will make it slightly bigger in diameter. Keep trying it in the mold hole to see when it gets to be an interference fit when you try to re install it in the mold block.

Tap it in per Bud's method and see if it will stay put when the mold gets hot. If it moves when it gets hot, try raising bigger welts with the prick punch.

Another method may be to put a couple of set screws in from the side to keep it in the hole. Use the ones that are hardened with the hex wrench drive sockets. You can grind a couple of little flats on the pin to give the set screws more purchase.

I use lots of Lee six cavity pistol bullet molds and the hold down plate screws tend to come loose. I simply drill and tap a set screw hole in from the side on them and that keeps the hold down screws from backing out of adjustment.

Tom