Need help! Lyman molds scratching.

[Tom Herman]

Hi Folks,

I need some advice. Here's what's happening: I cast outside, and apparently I think I must have transferred some dirt or sand from a 2x4 that I was using as a mallet to a couple of my four cavity Lyman molds. The 2x4 has been replaced with a rubber mallet to eliminate a possible source of contamination.
The sand particles apparently got between the sprue cutter and the mold, embedded themselves somewhere, and this caused drag marks across the mold and sprue cutter.
I took both molds apart, and tried to lightly file where appropriate, and then worked to buff out the scratches with 220, 400, and 1500 grit sandpaper respectively, cleaning with alcohol before proceeding to the next smaller size grit.
This seemed to help somewhat, but now I'm to the point where I have sprue cutters that have some pretty big grooves in them, and no matter what I seem to do, even just opening and closing them a few times after sanding and cleaning starts more scratches.
It seems that the sprue cutters are softer than the molds. If I just notice a scratch on the mold, I check the cutter and it already has a huge area of galled metal.
Am I sunk? I have new sprue plates coming, but that's not a full solution as I still need to figure out what to do with the molds themselves.
Thanks as always for your advice and help.

Happy Shootin'! -Tom

[stubshaft]

Drop down to the bottom of the page and go to the Bullshop site. Look under lubes and get the sprue lube.

[montana_charlie]

I'm to the point where I have sprue cutters that have some pretty big grooves in them, and no matter what I seem to do, even just opening and closing them a few times after sanding and cleaning starts more scratches.

The existing 'grooves' in the sprue plate will remain until the plate is replaced, or it is 'resurfaced' entirely.

But if new scratches are appearing, there is only one source...and that is the mould top. Examine the tops of both mould halves with strong magnification. If you know where the scratch exists on the sprue plate, you know about where to look at the mould.

A jeweler's file, or a stone, can be used to remove burrs or 'high spots' that are scratching the sprue plate.

CM

[Tom Herman]

Appreciate the advice, MC & Stub Shaft!

I have the Bullplate order form printed out, will get the sprue cutter lube.
And I will examine the mold under a 30X stereo microscope, and treat accordingly.

Happy Shootin'! -Tom

[RayinNH]

Tom at this point you want to find the source of the scratching and eliminate that from further happening. As far as the scratches they probably won't hurt anything and may even help venting...Ray

[stocker]

Tom: Check the outer edges of the mould block that the plate passes over. Also the top edges where the mould halves meet.Look for little dings or burrs on the edge. Remove them if you find any using a hard Arkansas stone. You can stone a slight bevel on the outer edges as well. Doesn't have to be large a bevel. If the block edges get bumped against a hard object it's pretty easy to throw a gall or burr up which will drag on the sprue plate.

[Phil]

Don't have the sprue plate screw too tight do you? You want the sprue plate to close on its own when you tip the mold. Big +1 on the Bullshop Sprue Plate Lube too. You'll wonder how you ever got along without it.

Cheers,

Phil

[runfiverun]

good advice right up there.
and a learning experience too.
i dont knock open my molds except for the first 2-3 when getting sprue up to temp the rest i open by hand.

[Tom Herman]

I have checked the top of the mold and the sprue cutter under 30X magnification... It's unreal how stuff shows up!
The sprue cutters are history... The new ones should be in by the weekend. I'll save the parts....
The molds themselves do have scratches on top. the edges look good, but some stuff looks embedded in the tops. I have work to do on them.
Lesson learned on not over tightening the cutter screws. Bull Plate will be on order shortly.
I can't physically cut the sprues on four cavity molds with my hands... I did that up to two cavity sizes. If you can cut the sprue on a four banger by hand, I salute you! I may try that once the molds warm up.
Otherwise, a smart tap with the mallet cuts the sprue. Sometimes the bullets stick in the molds, then a rap to the sides releases them.

Happy Shootin'! -Tom

[anachronism]

I use a hammer handle as a mould mallet. Mine is a new one & never had a head on it, it's always been used as a mallet. I hold it at the small end. It seems to be sized just right for casting. If worse comes to worst, you could always have the tops of the mould blocks surfaced at a machine shop. I can't break sprues on a 4 cavity mould either, and I'm bigger 'n you.

[WHITETAIL]

Tom, +1 I also had that problem when I first started.
Then the boys here set me straight.
Use a new hammer handle, It works great!

[JIMinPHX]

My first mold was a brand new Lyman. Within two days, I had galled up the top of it with circular gauges. I had been using a pencil to lubricate the sprew plate. Apparently this didn't work as well as one would have liked. After cleaning up the tops of the blocks, I got some hi temp grease from the auto parts store. This worked out much better. Bullplate lube is probably better than that, although I haven't used it myself yet. It's a shame that good molds need to get damaged for people to learn things like this.

[Le Loup Solitaire]

Some folks in an effort to ensure that bullet bases are sharp and cut clean, will sometimes tighten the controlling screw or bolt a little too much. The sprue cutter should swing freely on/by its own weight....but not be a sloppy fit (move up and down in relation to the tops of the blocks). As such it also helps with proper venting. As for how to move the cutter plate around, a hardwood mallet, a hammer handle, a section of hickory handle from a sledge, maul or even a porch rail will work fine. I have used those and also a plastic mallet. I thought that the plastic would not last, but after many years and knocks it is still fully intact. Galling is avoided by dusting the tops of the blocks with powdered graphite if necessary. Casting too fast and too hot will invariably cause lead smears on the underside of the sprue cutter and/or across the tops of the blocks. Getting rid of those can be done by rubbing them with a pointy corner of an ingot with enough pressure applied; the ingot surface will pick up/absorb the smear. Enjoy casting. LLS

[cuzinbruce]

For the sprue plate, disassemble the mould and stone the bottom of the plate, flat on a ceramic or Arkansas stone. I use a large bench stone and just work it on the flat. If there are burrs or whatever on the top of the blocks, you can gently touch them up the same way, unless they are near the stop pin. It also helps to stone a slight bevel or just break the edge on the outside edges of the sprue plate, also the outside edges of the mould blocks, just around the perimeter, not where the two halves meet up. Even badly galled blocks and sprue plates can usually be saved.