Machinist help needed

[joeb33050]

I have a new mold that won't cast many good bullets, 12 in an hour is
the record for good. I believe that there's too much metal in the sprue
plate and mold, and want to reduce the amount of metal in steps and
keep testing. I don't even have a vice here in the condo, so I need a
metal removal guy to help with this experiment. First step is to cut
down the sprue plate.
Is there anyone out there who will volunteer to help? I think a milling
machine would be needed to start taking metal off the mold.
Thanks;
joe b.

[kenjuudo]

PM sent.

jim

[redneckdan]

if'n you still need help, I know of a surface grinder on campus that needs some lovin.

[garandsrus]

Joe B,

Why do you think the problem is too much metal in the mold/sprueplate? The only way I could see that being a problem is that it doesn't retain enough heat while casting.

Do you pre-heat the mold before casting? I would suggest that you pre-heat it to pretty hot using a hot plate. You could also dip the corner of the mold in the molten lead until it's hot.

If the amound of metal is the problem, I would think that the hot mold would start out casting good boolits, at a normal pace of several per minute (for a new record!) for several minutes, and then the boolits would start to have fillout problems as the mold cooled down.

John

[cherok9878]

joeb33050, give us a little more info, what kind of mould are you using? Give name(maker) and number. Many here are experts in solving problems with moulds/casting...................larry

[Jon K]

Joe,

I also have to ask, why do you think hat you do? It has been my experience that the thicker sprue plate works better.
Grananrus has a point, what temp are you trying to pour at?
Also did you spray the inside of the mold with release agent? If you did, you may have clogged the vent lines on the face of the mold.
Another thing, that may help, is to open up the pour caity of the sprue or your ladle, so the alloy can flow easy, and create a generous sprue.

Often times 1st time out the mold isn't user friendly right away.

Lots of contributing factors to a good pour, List every detailed step you use, someone here will help you.

Jon :coffee: :castmine:

[joeb33050]

This is a Borton-Darr mold for a 185 gr. spire point buillet. I bought 50# of 25:1 as recommended, the mold doesn't fill out, mostly the point. Yesterday I cast 138 311299s of 25:1 in a Lee 20# ladle pot 4X inspection, 207.8-208.4 grains in 2 hours. Last time out in over an hour 87 bullets, 12 good with the Darr mold. As instructed I push the sprue plate open with a gloved hand, all molds are right handed, needing the mallet from time to time results in a big flurry of activity. I've whacked sprue plates open with plastic mallets since before Kennedy was inaugurated, without a problem.
The Darr mold has 13.2 in^2 of surface area, the Lyman 311299 has 7.98 in^2. Darr sprue plate 3 in^2, Lyman <1 in^2.
The Darr mold is too big, too much mass and too much surface area, it won't get or stay hot. It's heating on the pot now, I'll give it 2 hours to stabilize, then try again.
Replacing the sprue plate would be the first step. Then there's a lot of iron that could come off the Darr mold, reducing both mass and area.
Jim Borton tells me to get a thermometer. I tell him the mold is too big.
If reducing the mold size won't allow me to cast good bullets, I'll get a thermometer. (No I won't.)
So, I need a machinist's help. Or advice from anyone who's cast more rifle bullets than I have.
As an aside, I'm surprised that 311299s at 25:1 didn't weigh more, they weigh ~206 grains in WW. Can this be right? Is my $1+/lb 25:1 really 25:1?
joe b.

[Bass Ackward]

As an aside, I'm surprised that 311299s at 25:1 didn't weigh more, they weigh ~206 grains in WW. Can this be right? Is my $1+/lb 25:1 really 25:1?
joe b.


Joe,

Hard to tell, but you can. At 200 grains of bullet weight, 25-1 should be about 6.5 grains heavier than a WW bullet poured from the same mold. Pure lead should be about 7 grains heavier than WW. So subtracting and you get about .5 grain difference between pure lead and 25-1. So it depends on what standard you have to compare.

[Pilgrim]

The amount of metal in the mould and sprue plate are NOT your problem. Don't machine it!

Actually, the mass of metal will help you get good boolits, but will also result in a slower production rate because it holds more heat, which helps fillout as the metal won't set up as fast. On the other hand, by holding the heat longer it slows things down as you have to wait longer between pours to cut the sprue plate. Your alternative is the BruceB casting method for rapid boolit production. If'n you aren't familiar with his method, do a search on this forum as its has been discussed a number of times. It works very well by all accounts. Back to your problem....

If you have problems with fillout of the bullet nose ONLY, then you need to SLIGHTLY increase the vent lines in the blocks at the boolit nose. If you have other areas of boolit fillout problems with the blocks, you will also have to work the vent lines in other areas of the blocks as well. Start out using a knife (like a fillet knife with a very thin sharp point) or very sharp pointed scribe. You want to be able to see that you are deepening the vent lines without actually seeing any metal being removed (no metal filings). You don't want to take too much metal out of the vent lines or you will get fins instead of lack of fillout. Don't ask...been there done that. The fins don't hurt anything as near as I can tell, other than your pride as being a boolit caster par excellance. You also will feel kinda dumb about screwing up the mould. Anyway...

In one extreme case I actually had to use a set of die makers files to both deepen and widen a set of vent lines to get good boolits from one particular mould. It gets a bit worrisome doing that because you can get real fat fins in a hurry if you screw up when using the file! You may have to work the vent lines over more than once, so don't get in a big hurry. Scrape them firmly with the scribe, heat the mould up and try it. If no good, repeat. In the worst case, you usually won't have to repeat more than a couple of times.

FWIW - Your casting method also can have a huge effect. One mould I have cast perfect boolits for the manufacturer. He ladle casts. I bottom pour from a Lyman furnace. I couldn't get good boolits for squat. It was about like your problem. I opened the vent lines a bit, and now get good bullets pretty much every cast. Ladle pouring apparently gave the blocks more time to vent is my guess. As a trial, you might slow down your pour speed with a hot mould so that the metal has more time to vent before set up. Or try ladle casting as another test. Make sure your put a fair amount of pour pressure directly over the sprue plate hole as the sprue forms. It seems to force the metal to fillout more while it is still plastic. Anyway...enough from the peanut gallery.........Pilgrim

[AZ-Stew]

In my experience, bullets having high percentages of lead and low percentages of tin or antimony (you're using 25:1 lead tin, which is close to 96 percent lead and 4 percent tin), require a lot higher temperature to cast good bullets. Do you know your pot temperature? That's where I'd start, rather than modify a good mould. Get your temp up to 800-850 and see if you don't get some good bullets.

Regards,

Stew

[omgb]

My vote is with those who say turn up the heat. Try this. Crank up the heat as high as it will go. When your alloy is so hot that it casts frosty bullets, you have reached the proper point. Now, pre-heat the mould for several minutes. Now cast some bullets at a brisk pace. use a plastic mallet to open the sprue. If you still get a high failure rate, try cleaning and degreasing the mould. Be sure to clean the vent lines. Now give it a go. If still no joy, PM me and we'll see if I can buy the mould from you and tinker with it.

[montana_charlie]

My vote is with those who say turn up the heat.
try cleaning and degreasing the mould.
Be sure to clean the vent lines.
I agree...
I agree...
I agree...
And I would add...inspect the mould faces to make sure there are no manufacturing burrs plugging the vent lines, right at the edges of the cavity.

Oh, yeah! Clean the mould...again...and be careful how you lube it.
CM

[KYCaster]

Joe asked:
'As an aside, I'm surprised that 311299s at 25:1 didn't weigh more, they weigh ~206 grains in WW. Can this be right? Is my $1+/lb 25:1 really 25:1?
joe b.'

BA replied:
'Hard to tell, but you can. At 200 grains of bullet weight, 25-1 should be about 6.5 grains heavier than a WW bullet poured from the same mold. Pure lead should be about 7 grains heavier than WW. So subtracting and you get about .5 grain difference between pure lead and 25-1. So it depends on what standard you have to compare.'


The few times I've had WW analyzed, it has been pretty consistant at 97 Pb, 2.5 Sb, .5 Sn. The 25:1 alloy is 96.15 Pb, 3.85Sn, so I would assume that the alloy with the higher Pb content (WW) would be heavier.

Sounds reasonable to me......
Jerry

[joeb33050]

Tuesday, 10/17/06, I turned the pot on all the way up and put the B. Darr mold on the top lip of the pot at 10:30 AM. Started casting at 1:15 PM, cast until 2:50 PM. Made 52 bullets from 184.9 to 185.5 grains. I would have rejected 1/2 to 2/3 of these bullets after looking through the 4X magnifier, but wanted some to work with in the breech-seater design.
The mold has no vent lines.
I haven't used any mold-prep stuff for 30 years, NEI sends a bottle with their molds but I don't use it, haven't needed to.
Forrest: During my lengthy failure to get a 223 Rem to shoot tiny groups I bought an Eagan 65 grain SC mold and an NEI 80 grain DC mold. The NEI mold was/is slow but acceptable, it must be hot. The Eagan mold was VERY slow in making good bullets, it's a big heavy mold with a big sprue plate. I took a hacksaw to the sprue plate, took a lot off, and the mold cast a lot faster. I'll put a picture up on the CBA site.
If I can cast other molds with the same alloy and pot and technique, I think the delta is the Darr mold.
J. T. Britt on the Cast Boolits site helped a lot, he is correct in saying tha the least intrusive changes are best, and has volunteered to try to cast with the mold before doing anything. I'm too fast to saw stuff off.
So I'll mail the mold to him, and wait for his results.
Thanks to all, even BuckStix;
joe b.

[montana_charlie]

The mold has no vent lines.
That is interesting. Any mould needs to provide a path for air to exit the cavity as lead flows in. Are the block faces perfectly flat? Victory Molds are not flat, and that is how they vent.
CM

[Tom Myers]

Joe

If you are casting pure wheelweights with an alloy that assays out to Kentucky Caster's values of 97% Pb, 2.5% Sb, .5% Sn , then the Specific Gravity of the wheel weight alloy should be:

SG = 1 / (0.97 / 11.345 + 0.025 / 6.7 + 0.005 / 7.33) = 11.1218

The Specific Gravity of a 1:25 alloy ( 96.2% Pb, 3.8% Sn ) should be:

SG = 1 / ( 0.962 / 11.345 + 0.038 / 7.33) = 11.11367

So your wheelweight alloy should be heavier than your 1:25 alloy by:

11.1218 / 11.11367 = 1.00073

Wheelweight bullets of 206 grains divided by 1.0007 would indicate that 1:25 bullets should weigh 205.856 grains.

If the bullets from your supposed 1:25 alloy are weighing an average of 208.1 grains ([ 207.8 + 208.4] / 2 ) then your alloy bullets are weighing (208.1 / 206) = 1.0102 times as much as the wheel weight bullets.

If we multiply the Specific Gravity of your wheel weight alloy by 1.0102 X 11.1218 we get a Specific Gravity of 11.2352.

Now we can calculate the percentage of tin in a lead tin alloy if we know the Specific Gravity of that alloy with the following function:

%Tin = 100 * (1 - 2.82565 + [ 20.712 / SG ] ) = 1.784% Tin

Which is the same as 1 part tin and 56 parts lead

1 / 1.7824 * 100 = 56.1

If your wheel weight alloy is not diluted with tin and your weights are correct and I haven't made any math mistakes, you are probably trying to cast with almost pure lead, which, in my experience, does not cast worth a darn in anything except a round ball mold.

You could try adding about 6.5 ounces of lead-free solder to 10 pounds of your alloy and see if that improves the casting qualities of that mold.

Hope this helps:

Tom Myers
Precision Ballistics and Records (http://tmtpages.com)

[ron brooks]

Tom,

Are you saying that lead free solder is all tin?

Thanks,

Ron

[Jon K]

Lead free solder is 96% tin.

Jon

[ron brooks]

Close enough. :) What is the other 4 %?

[Tom Myers]

The other 4% varys according to the brand . I have seen some with antimony but most of what I have seen for sale around here had Silver in it. "Hi-Yo Silver Awayyyy - Who was that masked man??".

Tom Myers
Precision Ballistics and Records (http://www.tmtpages.com)

[LET-CA]

Tom,

Are you saying that lead free solder is all tin?

Thanks,

Ron


I have several one pound spools that are 96% tin and 4% antimony. It sells for about $10 a spool locally here in Sacramento.

[ron brooks]

I have several one pound spools that are 96% tin and 4% antimony. It sells for about $10 a spool locally here in Sacramento.


Thanks, this is great to know I went looking yesterday for 50-50 bar solder and the local hardware store didn't have any and couldn't order any. I saw spools of the lead free solder and was wondering what it was made of. This sounds great. Ought to be perfect for adding tin to wheel weights.

Thanks again,

Ron

[charger 1]

Joe B,

Why do you think the problem is too much metal in the mold/sprueplate?
John

Ya thats a new one on me. The LBT's I have sprue up enough metal to make another set of boolits ,yet not a prob

[Phil]

I've used a lot of Darr molds and never had that problem. It just has to be something else. Alloy not as advertised or something because I've cast down to 30:1 with nary a hitch. I can guarantee you that the thickness of the sprue plate or size of the blocks isn't it.

Cheers,

Phil