Did I ruin my mold

[basti0076]

I did a fairly long 5 hour production run with my MP molds .360 170 gr Keith on Saturday. Prior to casting I lubed it with very little 2 stroke oil. The casting session went good so far except a minor lead built up toward the end. But that was my fold because I casted pretty fast.
After my casting was done, I went over to the work bench to clean and lubricate the mold for storage.
While preparing it for storage I noticed pretty hard and rough running marks at the pivot point of the sprue plate. I tried to smooth it out because I noticed a fairly large gap between the mold body and the sprue plate.

I’m gonna attach a picture of the mold body’s top just to point it out in a clear way.
Maybe someone can tell me if it is ruined or not. I’m a rookie in the casting business and not sure about this.

Thank you so much and have a good day.

Cheers

Sebastian

[Recycled bullet]

Heat the mold with propane flame then use the oily rag to wipe and when it is got enough to steam the two cycle synthetic oil the smears should come off. After it cools polish the top of the mold and bottom of the sprue plate with a strop glued to a flat piece of wood and the lead will not stick so easily in the future.

[imashooter2]

Galling at the sprue pivot is pretty common with aluminum molds. Get a fine file and draw file off just the high points. Then apply a small amount of high temperature anti seize compound and continue casting for many years.

[justindad]

I’ve used a knife sharpening stone to remove galling from the top of the mold block. Aluminum can gum up your stone, so pay attention. And wait a little longer before opening your sprue plate.

[pworley1]

Your mold should polish up ok. You need to slow down your casting.

[Bazoo]

No, its not ruined. You can remove those circular ridges easily with a light touch. I would use a fine file to start, very carefully. You have to make sure you do not get over into the edge of the cavity. Once you get it 95% with a file, you can use a stone or a piece of sticky backed sandpaper on a flat stick to get the last 5%.

If the mould top gets damaged in such a way that the mould is "ruined", do not fret as the mould is not actually ruined. You can always have a few thousands removed from the top of the mould and bring it back into service. Eric Ohlen, hollowpointmold.com has repaired a mould top for me.

[bosterr]

I use a single edge razor blade and hold it at a very low angle and it takes lead build-up right off the top of the mold. If I remember to keep a cotton swab handy dampened with synthetic 2 stroke oil this lead build-up never happens.

[basti0076]

First of all, thank you so much for helping me out.

I managed to smooth out the surface of the mold body quite good. I took a file and wrapped it in 400 sand paper, like I learned during my mechanics education. During that process I checked the height quite often with a square.
After the galling was solved I cleaned the surface from the lead. I used the method suggested by Recycled bullet and what should I tell, it worked pretty good. Yes there a few markings noticeable but it’s perfectly smooth by the finger touch.

There is still a bit of space ( it’s hard to get a sheet of paper in) between the mold body and the sprue plate, but that’s caused buy the construction, at least in my eyes.

[Wheelguns 1961]

I keep a rag with a little 2 stroke oil handy while casting. If lead is sticking to the top of my mold, I will wipe the top of the mold, while the cavities are filled with lead, and the bottom of the sprue plate. This stops lead from building up. The mold must be hot and up to temp beforehand. A tiny bit goes a long way.

[405grain]

Now that you got the mold cleaned up, lets address what caused the problem. You weren't waiting long enough before opening the sprue plate. When you cast your bullets, first the alloy will solidify, then the solid alloy will change from being shiny and will take on a duller shade. This is when the alloy has fully solidified. You can actually see when the puddle on the top of the mold changes color and goes from shiny to dull. Once the alloy turns dull it is OK to open the sprue plate. If you have lead smears on the top of the mold blocks, you'll likely also have them on the bottom of the sprue plate as well. You will also need to remove that lead from the sprue plate. A good trick to help prevent lead from sticking to the sprue plate is to take an ordinary pencil and scribble graphite (from the pencil) all over the clean surface of the bottom of the sprue plate. Lead generally won't stick to this.

[Bazoo]

I use graphite on the top of my moulds, in the form of a carpenter pencil. Then if I have any buildup, i scrape it off with the pencil.

[stubshaft]

Looks fine! I wouldn't worry about it.

[Cap'n Morgan]

I use graphite on the top of my moulds, in the form of a carpenter pencil. Then if I have any buildup, i scrape it off with the pencil.

It sounds like a good idea. Molykote powder or paste would probably do the same. The idea is to get the surface "contaminated" so the galling wont happen.
The lead smear is wetting the mold surface like when soft soldering. The molecules of the two metals will actually combine in a very thin layer, which is probably why the galling often will come back.

My dad told me how he used steel-on-steel bushings on the front fork of his JAPP speedway bike. He gave the fork legs a good rubbing with molykote powder and a leather strap and never had problems with excessive wear or any galling. Normal bronze bushing, on the other hand, would wear down fast from the cinder dust.

[45DUDE]

I have taken the spring off a few of mine and replaced with a flat washer. I do like post #3 and file a bit if it effects anything. Yours doesn't look bad enough to file yet. Maybe just a touch up. I drill my Lee molds and install a set screw for the sprue plate screw but tension needs to be set when the mold is at operating temperature. I wish the Lee molds came factory with a set screw. As a matter of fact I bought a belt sander that does a better job than a file for smoothing a mold.