Dimples Bases

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Castaway
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Dimples Bases

Post by Castaway »

Tried to post pics but not able to. Casting from a Hoch, nose pour mould with 20:1 alloy. After the mould came up to temp, I was casting good bullets with crisp bases. Technique is to lift my dipper through the melt three times and pour, leaving a generous puddle. In the middle of the pot, the bases started having dimples, much like a golf ball. The rest of the bullet could be used on a for sales advertising pic of what the mould can do. No dimples anywhere else. Some dimples larger than others. The dimples aren’t scrapes from the sprue plate nor are they dross, simply dimples. I fluxed, no help. Tried to pour faster, no help. Let mould cool between pour, no help. No specific pattern but I scraped the bottom spruce plate with a hard, dry piece of bamboo. No help.
bobw
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Re: Dimples Bases

Post by bobw »

How many degrees are you running the melt? are your bullets frosted as well? Nose pour hochs are large molds. Hold heat well.. bobw
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Woody
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Re: Dimples Bases

Post by Woody »

I have a 550 grain .45 cal Hoch "Style" nose pour. I too cast around 20/1 alloy. I must cast fast and furious to obtain good results. My melt is 800 degrees and If I slow my casting cadence, the mould cools too much.

I don't know why you are " lift my dipper through the melt three times", The melt is not stratified by alloy or temp. Fluxing the melt doesn't do anything to improve the melt. It just returns some of the oxides in the dross back to metal.

My thought is to cast hotter and faster and see what that does for you. I have not experienced the "Dimples" you are.

Good luck,

Woody
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powderburner
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Re: Dimples Bases

Post by powderburner »

When those happen there is a bit of contamination on the plate in my limited experience.
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Castaway
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Re: Dimpled Bases

Post by Castaway »

I don’t know the temp but the melt flows very freely. Bullets aren’t frosty. Why dip three times? It can’t hurt anything and at the risk of Kenny’s wrath, I think I remember where he advised that. Apologies if I remember wrong. Forgot to mention, it’s a 520 grainer. As far as contamination on the plate, before seeing this, I had just pulled the plate off and polished it and the block. Cleaned with rubbing alcohol when done. If conditions are right tomorrow, I’ll fire up the pot and try again in the morning. Thanks for the suggestions
gunlaker
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Re: Dimples Bases

Post by gunlaker »

My nose pour Hoch molds are all for lighter bullets for my schuetzen rifles, but I have the same experience as Woody does. Fast and furious to get good bullets. I literally fill the mold, wait for the sprue to harden then cut the sprue and dump the bullets with no wait time in between any of the stages.

With my BACO molds my tempo is much slower, maybe 20-25 seconds between sprue cut and opening the mold depending on the air temperature in my casting shack. When the temperatures are near freezing I wouldn't even try my Hoch nose pour molds because I don't think the bases would ever fully fill out.

With that said, I haven't seen dimples in my bases either, just rounded edges on the base if I don't cast fast enough.

Chris.
Geologist
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Re: Dimples Bases

Post by Geologist »

I have seen dimples when the mold is not venting properly or if the melt is still de-gassing after fluxing or if the sprue plate (bottom side) has for example oil on it.
Castaway
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Re: Dimples Bases

Post by Castaway »

Geologist, by talking to an avid casting friend, he suggested something similar. I will clean the vent cuts as a first step. I may also be “dumping” too much melt at one time and trapping air below a column of lead. Thinking about the dimples, they were symmetrical and rounded at the bottom. I should get back to casting in a few days and see.
gunlaker
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Re: Dimples Bases

Post by gunlaker »

When you figure it out, please let us know what fixed it.

Chris.
Castaway
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Re: Dimples Bases

Post by Castaway »

Geologist had it right. I cleaned the vent lines and poured a bit slower this morning, the bullets came out they way they’re supposed to. Thanks to all for the input.
gunlaker
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Re: Dimples Bases

Post by gunlaker »

Castaway wrote: Mon Nov 28, 2022 9:23 am Geologist had it right. I cleaned the vent lines and poured a bit slower this morning, the bullets came out they way they’re supposed to. Thanks to all for the input.
Thanks for posting the solution. That knowledge might come in handy one day :-).

Chris.
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Re: Dimples Bases

Post by JonnyV »

I’m late to the party but I had the same problem last year getting ready for the Quigley. The dimples are probably caused by air being trapped in the mold. Good cleaning really helps. I even used the backside of a razor blade point to drag out the vent cuts (gently) and now no more dimples.
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