mould fill out

[Tag]

I have a problem with one of my accurate molds its a 9mm 147, Im sure its something I'm doing but I can't figure out what it is. so here is the problem it will not fill clear to the top of one of the cavities even with a puddle on top, any ideas

[williamwaco]

Perhaps -

I have seen this happen when the sprue plate was adjusted too tight to let the air escape from the top of the cavity. This was with a bottom pour spout tight up against the sprue plate.





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[1Shirt]

Yep, would bet it was to tight a sprew cutter.
1Shirt!:coffee:

[geargnasher]

Tom's mould blocks and sprue plates are so precisely machined and fit so well together that they are literally air tight. I had similar problems with the first (gen II believe) one I got from him, my fix was to take a very fine file and "break" the edges of the blocks at the top where they meet under the sprue plate, thus leaving a slight "vee" from the cavity bases to the front and rear ends of the sprue plate for air to escape.

More recently, the moulds he's made for me have this done already, in a similar manner to the outside edges that he "breaks" to prevent them from cutting the user when handling. The sprue plate on his current moulds is also adjustable as has been mentioned, but you don't want to make it too loose or you'll have problems with the bases being square.

One other thing that helps a lot with fillout when casting with a bottom pour is the "swirl pour" technique, where you tilt the mould slightly (about 10 degrees or so) toward you by lowering the handle end, then let the stream drop into the mould right at either the left or right edge of the sprue hole (depending on which hemisphere you live in) which sets up a spiraling effect of the alloy within the cavity and helps purge the cavity of air. Let the alloy drop about 1/4" from the spout to the sprue plate to give the stream of displaced hot air out of the mould some room to spiral around the stream of lead dropping into it like a double-helix. Pouring this way and setting up the vortices of alloy and purged air will actually create an ever-so-slight vacuum in the cavity at the end of the fill because of the inertia of the purge air stream spiraling upward. I've observed this effect several times when smoke from mould lube gets pulled into the cavity through the vent lines and is expelled by the next fill, the tiny wisp of smoke will corkscrew around the fill stream if you do it right. Of course if you apply mould lube correctly there won't be enough to gas-off and smoke the cavity where it can cause fillout problems, but I'm just mentioning this to back up my statements about the vortex from swirl-pouring.

Gear

[Tag]

Ok, so you guys think its air trapped under the spure plate keeping the lead from entering into the last part of the cavity. That at least gives me a starting point. Thanks a lot, you guys are great

[Wayne Smith]

The only real other reason would be a too cool mold. I assume you have ruled this out.

[Tag]

The mould is not to cold the other cavity throws a perfect boolit, I kept casting untill boolits started to frost then slowed a bit. I used bullplate to lube after the mould was good and hot so that should not be the cause either. going hunting tomorrow I'll have to try again when I get back

[Cadillo]

Consider everything mentioned above, and if nothing else works, you might try what I learned by chance that has helped me a lot. I cast with a ladle and all my moulds are four cavity types. With all my iron moulds the cavities fill OK by starting at the end farthest from the handles.

When I got my first Mihec brass mould, the first cavity(farthest from the handles) would never completely fill to create a base, regardless of how hot my mould was. But, if I start filling cavities at the handle end, everything works just fine. This is the case with each of my three Mihec moulds. The cavities must be filled from the handle end first, or things go awry. For me it's an easy fix that yields great results. I don't know why, but it just works.

[Tag]

Wow that is strange! if nothing else I'll defently try it...........Thanks

[williamwaco]

One other thing that helps a lot with fillout when casting with a bottom pour is the "swirl pour" technique, where you tilt the mould slightly (about 10 degrees or so) toward you by lowering the handle end, then let the stream drop into the mould right at either the left or right edge of the sprue hole (depending on which hemisphere you live in) which sets up a spiraling effect of the alloy within the cavity and helps purge the cavity of air. Let the alloy drop about 1/4" from the spout to the sprue plate to give the stream of displaced hot air out of the mould some room to spiral around the stream of lead dropping into it like a double-helix. Pouring this way and setting up the vortices of alloy and purged air will actually create an ever-so-slight vacuum in the cavity at the end of the fill because of the inertia of the purge air stream spiraling upward. I've observed this effect several times when smoke from mould lube gets pulled into the cavity through the vent lines and is expelled by the next fill, the tiny wisp of smoke will corkscrew around the fill stream if you do it right. Of course if you apply mould lube correctly there won't be enough to gas-off and smoke the cavity where it can cause fillout problems, but I'm just mentioning this to back up my statements about the vortex from swirl-pouring.

Gear


Gear:

I don't know about swirls or vortices, but I have discovered that troublesome molds will almost always get right in step if I let the metal drop about 1/2" and land on the sprue plate on the side of the conical cut in the sprue plate. Like pouring it down the side of a funnel, not directly into the sprue hole. I do not however tilt the mold. I will certainly try that next time.






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[geargnasher]

Try dropping the stream just at the edge of the hole without hitting it, or just barely grazing it. Imagine you're trying to drop the stream straight onto the ogive of the nose but with the mould at an angle so the stream deflects just enough to set up the spiral action, like filling a glass with water by holding it at an angle under the faucet and letting the water stream hit the side of the glass.

Gear

[WHITETAIL]

+1 on pouring it to the side.
Works for me.:bigsmyl2:

[williamwaco]

Try dropping the stream just at the edge of the hole without hitting it, or just barely grazing it. Imagine you're trying to drop the stream straight onto the ogive of the nose but with the mould at an angle so the stream deflects just enough to set up the spiral action, like filling a glass with water by holding it at an angle under the faucet and letting the water stream hit the side of the glass.

Gear


Made some Lee .309-170-F bullets with this method. It works really well and the bullets shoot really well.



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[jblee10]

I like gearnasher's post. Let the cavity vent out the sprue hole. Also. pre heat alum molds upside down on the sprue plate.