View Full Version : Mold out of round
35isit
12-13-2020, 05:47 PM
RCBS 357-180 SIL. .360-.361 on high side. .356-357 on low side. measured with a micrometer not a caliper. It had always thrown round boolits at .358/.359. I had a lead deposit on the bottom band of the front cavity. I call myself using just enough heat to remove it with a light scraper. Can I make round boolits again?
country gent
12-13-2020, 05:58 PM
Use a magnifying glass and look at the faces for small buildups holding the blocks slightly open. look hard around pins an in pin holes for build ups. A build up in the cavities wont hold blocks open to make an out of round casting. Look for build ups of tin/lea. carbon, soot, burnt lube. Your only talking a .004 build up. Clean faces with a stiff brush and thinner then dish soap an water really working up a lather to float crud off. Use a bamboo skewer or fine awl in the vent lines and clear them also.
35isit
12-13-2020, 06:12 PM
Thanks
Bazoo
12-13-2020, 06:20 PM
Could be your alignment pins backed out a bit, causing the halves to close off center to the cavity. Might check for play there.
Conditor22
12-13-2020, 08:53 PM
After carefully inspecting the mold for any lead buildup on the face,
Removing the handles, I have clamped the mold in a vise to re-set the alignment pins.
Can you see light through the closed mold when you hold it up to a light source?
beagle
12-13-2020, 09:33 PM
Easiest way to set pins is to drill holes in a lead ingot and tap in and out with a brass drift of the right size. No stress at all on the blocks that way.
I'd check this first./beagle
35isit
12-17-2020, 09:22 AM
I got the mold out last night. There were several places with lead buildup on the face of the mold. I got my son to remove them for me. I have no "eye" for fine detail work. I'm going to try it again this weekend.
You guys on here are the best.
country gent
12-17-2020, 12:57 PM
A single edged razor bade laid flat along the blocks works well for shaving the deposits of. Next is a exacto knife. work slow and carefull
Bazoo
12-17-2020, 01:14 PM
I use a bronze toothbrush or even a choreboy for heavy stuff. Always scared around the cavity edges of rounding. But I mainly try to remove deposits with a pencil when the mould is hot.
gwpercle
12-17-2020, 07:06 PM
I got the mold out last night. There were several places with lead buildup on the face of the mold. I got my son to remove them for me. I have no "eye" for fine detail work. I'm going to try it again this weekend.
You guys on here are the best.
Just a speck of lead on a block face will keep them from closing and hard to see even with young eyes . Sounds like you found the problem ! Now it should do right .
Gary
onelight
12-27-2020, 04:55 AM
I use the flattened mouth of a cartridge case filed or belt sanded to the shape I need to scrape lead off iron molds.
Traffer
12-27-2020, 05:56 AM
I heat up the mold and use a toothpick or a soft stick like a small diameter dowel to scrape the surface. No chance of scratching that way.
RickinTN
12-27-2020, 11:25 AM
Bamboo skewers are great for this. Hard enough to remove what you want but not hard enough to damage a mold.
I save them every time I get the chance from restaurants.
Good Luck,
Rick
JWFilips
12-27-2020, 07:30 PM
Out of round bullets get round pretty fast once fired!
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