Author Topic: mold fillout (Read 826 times)

hiram · « **on:** June 17, 2004, 12:33:18 PM »

I have 2 lee 10# bottom pour pots. I just got an NEI 525 mold 348a. The hottest 1 pot gets is 700 according to my thermometer. The first band above the base does not always fillout sharp. It is rounded.

What can I do to avoid this???

The 2 pots have different size holes. Would you use the larger or smaller hole? The fillout appears to be about the same.

Thanks

Cat Whisperer · « **Reply #1 on:** June 17, 2004, 03:38:22 PM »

Two things that will help:

1. Get the mould (since you are maxed out on the alloy) hotter.
2. Smoke the mould - kitchen match, candle etc.
3. Add a little tin to the alloy.

(Three kinds of people in the world - those that can count and those that can't.)

hiram · « **Reply #2 on:** June 18, 2004, 09:00:08 AM »

The alloy I'm using is 20:1. The base fills out, the bands 2, 3, and 4 fill out, but not band 1, the first one in front of the base.

I have sprayed the mold with midway's mold release and on another casting occasion, with a moly spray--the results are the same.

Leftoverdj · « **Reply #3 on:** June 18, 2004, 01:20:04 PM »

Put a blanket around your pot. Aluminum backed fiberglass insulation cut to fit and wired in place should get you another 50 degrees. If that doesn't work, you may need a new thermostat. They are available from Lee for around $10.

dakotashooter2 · « **Reply #4 on:** June 18, 2004, 05:18:09 PM »

Or try letting the mould overflow. I have one mould that will only fill if I keep pouring after it appears filled. Messy but it works for me.

hiram · « **Reply #5 on:** June 19, 2004, 09:25:51 AM »

I tried the insulation and it worked. With the pot at least half full, I got 50-60 extra degrees. But still had some bottom band fillout problems. I notice most of the problems occurred in the cavity which is closest to the pivot screw of the sprue plate. There is some play in the plate to allow it to swing, but there is less space closest to the screw and more space as you move to the opposite end of the plate--a taper. I read in a Paul Matthews book that incomplete fillout is an effect of not getting the air out of the mold.

I have .002" stainless shims used in locksmithing. I re-adjusted the sprue plate with a shim near the pivot screw and one at the far end so I now have a parallel space across the top of the mold to let air out. I've eliminated the tapered air space. I'll cast more during the week hoping to see a difference. If results are better, I might need a little space more, maybe not, being careful not to create fins on the base because of too much space.

LAH · « **Reply #6 on:** June 19, 2004, 02:09:22 PM »

The place that doesn't fill out, does it appear different in color or texture?

Haywire Haywood · « **Reply #7 on:** June 19, 2004, 05:43:46 PM »

I got far fewer defects like you describe when I stopped using the Lee Bottom Pour and started using the Magnum Melter and a ladle with the spout drilled out to 3/16". Dan at Mountain Molds told me that the bottom pour doesn't have enough flow for the heavyweights. I still use it for 38s and the light 45s (160gr) that I shoot for SASS matches tho.

good luck,
Ian

hiram · « **Reply #8 on:** June 19, 2004, 06:27:32 PM »

Sometimes the band that doesn't fill out appears frosted.

I could drill out the spout to a larger size. First I'll cast and see if my .002" parallel spaced sprue plate makes a difference.

Leftoverdj · « **Reply #9 on:** June 20, 2004, 05:36:16 AM »

Hiram, you can also try casting with sprue hole jammed up against the pour spout. This puts the full weight of the alloy into pressing metal into the mould and gets the metal into the mould a little hotter.

I find that some of my moulds fill out better when I am using my 20 pound pot and attribute that to the greater head of alloy.

hiram · « **Reply #10 on:** June 22, 2004, 02:56:56 PM »

I bypassed the Lee thermostat and got 900+. Still no good.

The sprue plate holes are .152". Can they be too small?

John Traveler · « **Reply #11 on:** June 22, 2004, 04:42:01 PM »

Hiram,

My old metal shop teacher friend fabricated an aircraft aluminum alloy sprue plate for the SAECO 4-cavity .38 WC bullet mold we shared and it cast like a charm! The change included making for much larger (about 2x diameter) sprue holes. He stated that the greater flow made for better fillout. He must have been right because both quality and productivity increased greatly!

Leftoverdj · « **Reply #12 on:** June 22, 2004, 05:51:31 PM »

Vent lines?

Could it be that that one band is not vented properly? Exacto knife down those lines is worth a try.

LAH · « **Reply #13 on:** June 24, 2004, 04:18:07 AM »

I like sprue cutter holes a little larger than most come, as some of you do.

If you have a driving band not filling out and it appears "frosted" it's telling you, at least this place in your mould is too hot.

PA-Joe · « **Reply #14 on:** June 24, 2004, 04:48:30 AM »

Try filling in the opposite direction. Front to back or back to front.

hiram · « **Reply #15 on:** June 24, 2004, 06:40:22 AM »

the sprue holes now are .152".

I tried filling the cavities in different order. The cavity closest to me, or the nut on the handle (however you want to take that), most often gives me the problem.

hiram · « **Reply #16 on:** June 26, 2004, 04:47:51 AM »

I called NEI. I asked about the size of the sprue hole. The answer was .189----mine are .152. Joel measured a hole and said mine are .150. I asked where did .189 come from? Hid answer was that he use to make the holes .189, but the small bullet casters said that .189 was too large. He went down to .150. I opened the holes to .189. Results are much better with some occasional rounded off bands. Casting at about 750 degrees.

How many 45 cal rifle bullets (500 gr range) are throwbacks for you fellas?

Are all the castings keepers?
Thanks

LAH · « **Reply #17 on:** June 27, 2004, 01:59:05 AM »

When casting with a single cavity 458 mould, the bullets weighing 500 grs., our reject rate is appox. 1%.
We cast the Lyman 457406 in a 4 cavity mould and it's easy for the reject rate to go to 10% if one isn't careful, the cause being over heating. Four each 490 gr. bullets in the same mould builds a lot of heat and care must be taken to cast slowing, allowing the mould to cool enough to prevent frosting which leaves a void on the surface of the bullet.

You'll find once the "rate of speed" and temp. range are established for the mould that rejects are very, very few and most of the rejects are really only less than perfect. These will shoot as good as the other perfect bullets in field (hunting and plinking) conditions. I shoot lots of "rejects" from our business here in the hollow. I can hardly shoot well enough to tell the difference.

hiram · « **Reply #18 on:** July 02, 2004, 04:07:08 AM »

It seems a friend and I discovered the problem. I used a spray mould release. When it got into the corners of the bands, it either insulated the corner and the alloy hardened prematurely before it filled the band, or it built up in the corner and clogged it.

I cleaned the mould with acetone, brake degreaser, and bug and tar remover, brass brush and then a soft brush on a dremal tool. Seems to be good now.

I have used mold release on other aluminum moulds without this problem, but I might not use it again.

Thanks for all you guys offering insight.