NEI mold challenge

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Tom Acheson posted this 3 weeks ago

I have a 3-cavity mold #379315. At the casting bench it doesn't quite close 100%. Just enough faint light between the cavities resulting in slightly bullets. It could be that I'm not using the correct handles.

Is there a preferred brand of mold handle?

Thanks!

Tom

 

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Tom Acheson posted this 3 weeks ago

.....finned bullets....

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John Alexander posted this 3 weeks ago

My NIE molds always worked fine with Lee handles.  Mine are all before Walt died. I don't know if they were different afterward.

If you can get those fins lined up just right they act just like a smart bomb.

John

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OU812 posted this 3 weeks ago

You may have a small piece of lead splatter in between mould halves...preventing closing . It can be hard to see. Or a burr at female alignment pin hole. I have never seen a pair of handles prevent closing.

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BudHyett posted this 3 weeks ago

The items I check when this happens: 

  • The fit of the handles as they close and are the handles not touching the mold on the inside. The handles should only touch the pins and not the mold halves. I've had to slightly trim the inside of the mold handles due to them twisting under pressure and preventing closure. This is best done in a room with subdued light by shining the light into the slot.
  • Deburring the alignment holes, both mail and female. Sometimes the male pin has a slight burr where it exits the mold half and this prevents closure. This is not always easy to see..The female side can develop a burr with the first few closings due to tight fit and will need the slightest touch to free up.
  • Lead splatter on the mold face. Brass wool and scrub. Scrub away from the mold cavity in long gentle strokes. Check each vent line for lead splatter or a burr at the cavity, best done with magnification.
  • Deburr the outside of the mold, all corners and edges and the sprue plate. A slight breaking the edge technique is sufficient. Sometimes the sprue plate sliding across the mold halves creates a slight burr each time it closes. .
  • With a problem mold, I sometimes add a thin split lock-washer to the sprue plate and tension the sprue plate down. This is most common on older RCBS molds with the thin sprue plates.  . 
  • Warp in the usage.We are dealing with metal that is precision machined where the slightest change in dimension becomes easily seen. I take two small c-clamps and press the mold halves tight together, gently place them on a hot plate at full temperature and leave them for twenty minutes. Take them off, let them cool to where they are warm to the touch and do it again three more times. This is as close to stress relief as I can get with my current setup. This has worked several times, but is an extreme last resort measure.   

Country boy from Western Illinois, living in the Magical Pacific Northwest

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Ross Smith posted this 3 weeks ago

I can add one more hint. On one mold the alignment pin(1 of 3) stuck out too far and had to be tapped in a hair.

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Tom Acheson posted this 3 weeks ago

Bud,

Good punch list....thanks!

Took the blocks out of the handles and examined the faces, no lead splatter and touched-up the female pin holes with a round Swiss Pattern file but felt no burr. When the mold is out of the handles and the halves are put together....no light. The handles are doing something to allow the light gap to appear. I don’t have any Lee handles but a couple of RCBS. The tongs of Saeco handles are too thick to fit in the slots on the mold.

Tom

 

 

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BudHyett posted this 3 weeks ago

File the inside edge of the handles along the edge for the entire length so there is no chance of the handle touching the mold Do this carefully, but the inside edge needs to only be strong enough to pull the mold apart.

RCBS handles are not necessarily square to the screw holes. My early RCBS handles show edges suggesting they were sheared rather than profile machined. This causes the mold to be pressed in some point that the mold faces are not able to close completely. Lee handles are thin which allows the mold to align as it pleases until full closure. Today, the RCBS handles have better profiles.

 

Country boy from Western Illinois, living in the Magical Pacific Northwest

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rhbrink posted this 3 weeks ago

Get a set of the Lee six cavity - universal mold handles they work great and fit just about every mold made with the exception of the Saeco's they do require their own handle. Cheap too! Or at least they were the last time I bought a set!

RB

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boatswainsmate posted this 3 weeks ago

Every NEI mold I have uses RCBS handles. 

 

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OU812 posted this 3 weeks ago

Wood handles will slip off over time and should be pinned.

Tightening some brands mould screws too tight will warp mould halves.

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TRKakaCatWhisperer posted this 3 weeks ago

Lee handles fit the best.  Alternately, I've drilled the holes slightly larger to accommodate alignment or clearance issues.

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Tom Acheson posted this 2 weeks ago

Don’t know how to indicate that this subject has been concluded but it has. I did find a pair of RCBS handles that work better than the Saeco handles that I had been using. 

Thanks to everyone who offered suggestions.  The consideration to use large Lee handles is the back-up plan.

Tom

 

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