Viberating The Mold While It Is Being Filled

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  • Last Post 19 July 2022
mashburn posted this 16 July 2022

Several years ago,a friend of mine had two molds, a Lyman and a Lee that would not cast bullets anywhere near the same weight. Both molds were of the same caliber which I can't remember what the caliber was, but both were large caliber molds.

We got the idea to apply vibration to the molds as they were being filled. We found an old electric shaver that did produce a pretty good rate of vibration. It was a two- man job, one to hold the razor against the mold and the other man to hold and fill the mold. We cast several bullets from each mold and after a cool down we began our weighing. The bullets from the Lyman mold were terrific, hardly varying in weight at all. We then weighed the bullets from the Lee mold, they were horrible in weight variation. I have never experimented with this technique since and wonder if anyone else has tried such an experiment.

Mashburn

David a. Cogburn

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RicinYakima posted this 16 July 2022

Yep, it works if there is a problem with displacing air in the cavity, i.e.. Lyman mould not vented well. The Lee has excess venting and the alloy runs into the "unused" space. This was written up in the 1970's in one of the NRA books. 

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Wm Cook posted this 16 July 2022

Lots of variables in that scenario. The fluctuating temperatures of iron versus aluminum molds, the cadence for letting the alloy set up, cadence for cool down etc. It would be a handful to control. That said filling the cavity is the goal. I hope you do wel and keep digging for answers.

The best I’ve found to do that was with a consistent mold temperature. And to do that I had to eliminate variables wherever possible. Right now I am blockheaded (narrow minded, fixated) enough to limit accuracy casting to Linotype, ladle cast, single cavity brass molds. Easy for me to say since I’m locked into .30 cal accuracy with a bolt gun for now.

One casting session I tried bumping the mold after the pour and at first glance it showed a difference in weight. Nope.

I wonder what practices commercial casters use.

What was the vibrating weight loss thing that was advertised 30 years ago by Suzanne Summer’s?

Ya think……

Thanks, Bill.

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mashburn posted this 18 July 2022

Hello Wm cook

We don't try to vibrate molds anymore. that was years ago and we were just playing to see if it would work.

Mashburn

David a. Cogburn

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Eutectic posted this 18 July 2022

As Rick said, vibration during fill has been tried. I have tried bumping to improve base fill which worked somewhat but adjusting fill rate worked better. 

I frequently run two molds at the same time. This allows time for the sprue to cool while you are filling the other mold. I get increased production and better quality because the cooling time is more constant. 

What I have not been able to do is run an aluminum mold and a iron mold simultaneously. The requirements for alloy temperature and casting rate (mold temperature) are so different I never could get it to work. 

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Wm Cook posted this 18 July 2022

Eutectic wrote: What I have not been able to do is run an aluminum mold and a iron mold simultaneously. The requirements for alloy temperature and casting rate (mold temperature) are so different

I'm curious if you could place a numeric value on alloy/mold temperature on Iron/aluminum mold temperature.  You mentioned running two molds so I assume you immediately pour after dropping the cast.  Maybe the # of cavity variable makes this impossible to answer.  Thanks, Bill Cook.

 

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mashburn posted this 19 July 2022

I run three molds at a time with cooling sessions.

Mashburn

David a. Cogburn

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