'Ridge' around cavity?

[bootsnthejeep]

Been going thru my moulds giving some much needed TLC. Was getting a lot of lead buildup from sloppy casting (those H&G moulds deserve, much, much better) so between the kroil and Frontier Metal Cleaner they've been getting some much needed pampering. Also treating the cavities with Kroil so I can experience the joy everyone's discussing from its use.

ANYWAY, dug out a mould I'd set aside because of lack luster results with it and think I've found the problem. Lyman 2 cav 429421(BW, whatever that means). Casted with a definite ridge at the parting line, not a fin but a noticeable ridge. Both sides and the nose. Just miked the storage slugs I left in it and they're a huge .435. Well, huge by my standards. I'd prefer to shoot as cast.

So, on closer inspection and after some scrubbing with the kroil, I see this faint ridge around the cavity. Just on the 'front' side (opposite the handles) of the mould. Can definitely catch a fingernail on it. On both cavities, both on the forward side of the cavity. The rear cavity has a much less pronounced ridge on the rear side of the cavity, but I can't catch a fingernail on it. Squeezing the blocks together I can still see light between them.

So, how to get rid of these? Flat whetstone? 600 grit on glass? Fine file? What's gonna be my safest bet to get rid of these?

I'll try to get a decent picture of it to post, my phone takes lousy pictures and no digital camera currently. But you get the idea.

Any thoughts?

Boots

[Bret4207]

Do you by anychance have anything like a Cratex abrasive polishing bob? Dremel sells them for their tools. Something like that would probably work if you just rubbed it back and forth along the like a couple times. So would a fine stone or even abrasive paper.

[Calamity Jake]

Use an X Acto knife, run the cutting edge vertical(standing like you were going to shave with it) along the outline of the cavity paying close attension to the corners, make severial light passes now stone the mould faces and check for closure, repeat is needed.

[theperfessor]

From your description it sounds like a dull cutter was used that raised a bur on the edge as the mold halves were closed on the cherry. If you put enough pressure on the halves when you close the vise you can sometimes push the bur flat where the cutter will cut it off, but not when it gets really dull. If this is the case the bur will show up on one side of one half and the other side of the other mold half. Has to do with cutter rotation and which edge is entering the material (no bur) and which is exiting (bur).

I have a Lyman 358477 that is like this, can see light around edges when closed. I was going to dress it off but this mold is right on minimum size and round and stoning off the bur will make it too small in one axis and out of round to boot. It casts and shoots OK and so I'm going to leave it alone.

If I was going to fix it I would press out the pins, rub it in a figure-8 motion on some oily 600 grit paper laying on a flat surface, and then put pins back in. If the halves close tighter I'd have to adjust the pins anyway.

[Springfield]

A fine file always works for me with steel moulds, with the LEE aluminum I use a very sharp knife blade and mostly scrape it off, not cut. Cutting can dig in and make a divot.