Lyman Sprue Plate Stop Bolt

[oley55]

I have a four cavity Lyman mold that when I barely snug down the sprue plate stop bolt, the head of the bolt sits too low and will not let the sprue slide fully into the closed position. When I back the bolt out enough to allow the sprue to close, the threads are so loose that the bolt will loosen further as the sprue plate is opened and closed.

I am reluctant to take any material off the sprue plate's stop notch or the bolt head. So I made a one and a half wraps around the threads with a strip of aluminum foil and that seems to have tightened the threads enough to keep it from backing out on it's own.

My question/concern is whether the dissimilar metals (steel, aluminum, cast iron) when repeatedly subjected to mold temperatures could become an issue over the long term. I'm thinking not, but.........

[country gent]

Look at the seat area and the bolt face for wear or indentation. The shoulder bolt as very little surface between the thread and shoulder dia.

You might measure the shoulder bolt and find the same new at McMaster carr, graingers, MSC, or on line they arnt overly expensive.Maybe contact lyman for one.

The only issue with facing the underside of the head will be the shoulder bolts are harder than hens teeth, definitely a job for carbide in the lathe. If the wear is on the blocks surface then a new bolt may not cure it. But a fix can be done by milling a shallow counter bore in the top face .125 deep and pressing a washer in then cutting to the needed height.

One other way that would work and be adjustable would be a set screw in the block and a tube id threaded to fit the set screw od of the dia of the shoulder bolt with thread above sprue plate then a self locking nut to set tension. This would also be adjustable for any wear that occurred.

[Taterhead]

This seems to be the way Lyman makes 4 cavs now. It is either a design or production flaw. 2 out of 2 of mine were like that. An easy remedy would be to use a set screw. I sent mine down the road since I couldn't find a satisfactory way to keep the bolt from turning.

[Ed_Shot]

Had that issue with one of my Lyman 4 cav's. A couple of wraps of thin copper wire fixed the problem. I do not see and do not anticipate any ill effects.

[DHDeal]

The permanent fix is to drill and tap the same size allen headed stop screw that is on the sprue plate pivot screw. Did I say that right? Anyway, an allen head stop screw will lock that that thing down.

I've modified most of my MP Molds to have a stop bolt/screw instead of the roll pin. That modification also includes a blind head allen screw to lock the sprue plate stop bolt. Tedious, but permanent and the molds cast even better. Personally I feel Accurate Molds (and one's like them) have the best sprue plate stops out there.

[oley55]

This is not a new mold, but no idea how old it really is. I picked it up used a couple years ago (7 molds with handles for $25) in anticipation of casting bullets someday and I am finally getting around to it. Is there a secret date code on these Lyman molds? (Lyman 358 91, 199/199, W 5) Pretty sure the 199 on each half is the production number to keep matching halves together. The W and spaced 5 on the lower left front block may have some date meaning(???).

Drilling and tapping a set screw in cast iron pretty easy so I'll do that. And thanks for the responses.

[DHDeal]

Since you're D&Ting the mold now, here is another trick I do. I cut a very small piece of 12/2 copper wire (same length as diameter or so) and drop it in the hole under the allen screw. That will protect the threads on the sprue plate screw and stop screw. As the mold gets hot as Hades, it will mold itself to the threads in time. Buggered up threads are a minor PITA in an iron mold, they are really a PITA in a aluminum or brass mold. This isn't my trick at all as I read it probably on here some time back.

Another mousetrap are allen screws with a brass tip from McMaster-Carr. I use these when I modify my MP Molds. More expensive for sure and they don't do much more than the piece of copper.

[oley55]

well I didn‘t have a set screw of the same 32 tpi and I didn’t have a tap for the 36 tpi screw I had,so I ended up making a few wraps with some thin copper wire where the threads meet the shoulder. I was able to crush the copper down when snugging to the right height. If it doesn’t work long term I’ll try the wire across the threads suggestion. Thanks to all for your help.

[beagle]

Good tip. I keep a piece of beaded chain in the drawer and when I'm having this problem, I cut off a bead and drop it in under the set screw. These are brass and squish down easy and protect the threads./beagle


Since you're D&Ting the mold now, here is another trick I do. I cut a very small piece of 12/2 copper wire (same length as diameter or so) and drop it in the hole under the allen screw. That will protect the threads on the sprue plate screw and stop screw. As the mold gets hot as Hades, it will mold itself to the threads in time. Buggered up threads are a minor PITA in an iron mold, they are really a PITA in a aluminum or brass mold. This isn't my trick at all as I read it probably on here some time back.

Another mousetrap are allen screws with a brass tip from McMaster-Carr. I use these when I modify my MP Molds. More expensive for sure and they don't do much more than the piece of copper.