My reject rate way to high! why

[gregg]

Been fighting this for a few years but getting good bullet this last deer season put me over the top. I got down to useing a bag of mag shot. I was useing WW up to that time. Now I went as far as useing 4 oz of tin in 10 lbs now going to try 8 Oz tin to 10 lbs of mag shot. Have a idea from Harry-O of putting my mold on the lead pot to wait for the sprue to harden? Been hard to keep the mold hot enough waiting for the sprue to harden. Lee 10 lb pot turned on hottest settting BTW. . Is it the WW is it I have not cleaned the pot enough when switching to the mag shot. Am I just gettting to old to cast at 54. Pulling what hair i got left out in SD

[Billwnr]

First thing, check your temperature as your alloy may be too cool. If it's in the 700+ range then your problem is something else. Do you oil your mould for storage?

[454PB]

The most frequent cause is temperature too low or an oil contaminated mould as Billwnr has said. The first thing I'd suggest is to clean the mould with brake cleaner or Gunscrubber. My Lee pots cast best with the thermostat set between 7 and 7.5 using WW alloy. That translates to around 725 to 750 degrees. It's possible your thermostat needs adjustment, there have been a few reports of Lee pots needing some tweaking of the thermostat. Zinc contaminated WW alloy is another possibility, how old are your wheelweights? Zinc seems to be showing up more frequently in the last few years. Do you flux the melt, and what do you use?

If you could post a picture of your defective boolits, it would make it easier to analyse.

[Billwnr]

My first thought was the thermostat was not doing it's job.

[gregg]

I bought one of the HF temp meters you all had talked about here. Think its running over 700 deg.
I should check again
Wheel weights are fairly new. I also was starting to blame them darn 6 cav lee group buys but the same thing going on with Lyman single cav molds I should get pictures your right. Its just not filling out in sharp corners just here and there. Do you all think more tin? Like I have said been casting for 34 years. Use to just use just WW alone. Have went thru many 5 gal bullets full in my life.
Oh ya flux Yup . Bullet lube . Felix lube.

[Buckshot]

...........All you should need is about 2% tin. Rounded edges sound like too low a temp for the alloy. Assuming the blocks are clean there shouldnt be an issue otherwise.

Bring your alloy up to temp, say 750 degrees. Set the blocks into the alloy, Since you said you had a 10lb pot, they'll be angled in kind of steep. Lift them out every now and then. When the lead no longer sticks to them our you pull up a bunch of half solidified lead, you are good to go.

Pour a boolit, and be prepared to wait some little bit till the spruepuddle sets up then drop the boolit and refill. Your dropped slug should be fully filled out, sharply and cleanly. Maintain a comfortable casting cadence and the blocks will cool off some so the sprue doesn't take so long to solidify.

If the boolits begin to show rounded features again, step up your casting speed or move the temp up another notch. Also, inspect the mating surfaces of the blocks. Make sure the vent lines are clean and complete. You can also put a tiny bevel on one block edge on the mating side (top-inside edge).

If the blocks are clean, and the alloy and blocks are in the correct temp range, there is no reason you should NOT get good boolits with each drop. You might also try having the lead stream his the edge of the chamfer for the sprue hole so it kind of swirls into the cavity.

..............Buckshot

[gregg]

...........All you should need is about 2% tin. Rounded edges sound like too low a temp for the alloy. Assuming the blocks are clean there shouldnt be an issue otherwise.



Blocks are clean



Bring your alloy up to temp, say 750 degrees. Set the blocks into the alloy, Since you said you had a 10lb pot, they'll be angled in kind of steep. Lift them out every now and then. When the lead no longer sticks to them our you pull up a bunch of half solidified lead, you are good to go.

Yup that how i do it. Speeds thing up preheating the mold

I'm going to recheck alloy temp?



Pour a boolit, and be prepared to wait some little bit till the spruepuddle sets up then drop the boolit and refill. Your dropped slug should be fully filled out, sharply and cleanly. Maintain a comfortable casting cadence and the blocks will cool off some so the sprue doesn't take so long to solidify.



Here I think could be the rub! I just read tonight about O-Harry resting his molds on the lead pot to wait for the sprue puddle to set up. It seems like it takes so long to harden the sprue?
But as we all know it we cut it to soon it pulls alloy right out of the base of the bullet. This seems to slow me down and makes it hard to keep the mold temp up. I have even tried to use a lead
ingot and or flat iron as a heat sink on the sprue.


If the boolits begin to show rounded features again, step up your casting speed or move the temp up another notch. Also, inspect the mating surfaces of the blocks. Make sure the vent lines are clean and complete. You can also put a tiny bevel on one block edge on the mating side (top-inside edge).

If the blocks are clean, and the alloy and blocks are in the correct temp range, there is no reason you should NOT get good boolits with each drop. You might also try having the lead stream his the edge of the chamfer for the sprue hole so it kind of swirls into the cavity.

..............Buckshot

Thank you all for the replys. Seems so simple ;-( so helps to review thur you guys .

[testhop]

...........All you should need is about 2% tin. Rounded edges sound like too low a temp for the alloy. Assuming the blocks are clean there shouldnt be an issue otherwise.

Bring your alloy up to temp, say 750 degrees. Set the blocks into the alloy, Since you said you had a 10lb pot, they'll be angled in kind of steep. Lift them out every now and then. When the lead no longer sticks to them our you pull up a bunch of half solidified lead, you are good to go.

Pour a boolit, and be prepared to wait some little bit till the spruepuddle sets up then drop the boolit and refill. Your dropped slug should be fully filled out, sharply and cleanly. Maintain a comfortable casting cadence and the blocks will cool off some so the sprue doesn't take so long to solidify.

If the boolits begin to show rounded features again, step up your casting speed or move the temp up another notch. Also, inspect the mating surfaces of the blocks. Make sure the vent lines are clean and complete. You can also put a tiny bevel on one block edge on the mating side (top-inside edge).

If the blocks are clean, and the alloy and blocks are in the correct temp range, there is no reason you should NOT get good boolits with each drop. You might also try having the lead stream his the edge of the chamfer for the sprue hole so it kind of swirls into the cavity.

..............Buckshot

buckshot tell me if this is wrong
the way i heat up a mould is use a bigger dipper and keep on pouring even when the mould is full till the sprue is malted down to normal
is yhis right or wrong and will it harm the moulds

tom

[Misfire99]

I would like to ask why you reject you bullets. Are they not filling the mold? Do they have voids at the base. Do they have lines running over them? What is the reason you reject your bullets?

You said you use a Lee pot but is it a bottom pour or are you using a ladle?

It might be as simple as your temp isn't high enough even though you have your pot set as high as it will go. Can you borrow a thermometer or another pot to test it out?

I think you have enough tin in it already. Adding more will just raise the cost and not solve the problem.

[Buckshot]

buckshot tell me if this is wrong
the way i heat up a mould is use a bigger dipper and keep on pouring even when the mould is full till the sprue is malted down to normal
is yhis right or wrong and will it harm the moulds

tom

..............If the alloy isn't hot enough no amount of pouring into the cavity or pouring and maintaining a huge sprue puddle will make any difference.

If your alloy is ultra hot it can fill a cold mould cavity and give a good boolit. The heat just cannot escape fast enough into the blocks. But we don't cast at temps that high. The alloy temp has to be hot enough to remain fluid long enough to fill the small detail areas. The blocks have to be cool enough to absorb the heat and begin radiating it so that the sprue doesn't remain liquid for too long a time.

I have a photo of 3 boolits (Lee 358-158RF). They were all cast with the pot set as high as it would go, which was right at 900 degrees. I was using a Lee 6 cavity mould. I cast 3 ways with this very hot alloy.

1) Filled after the mould was to temp required a substantail (comparatively) time for the sprues to set up enough to be struck and the boolits dumped. The boolits had a surface that looked like electro-galvanizing which is the best way I know to describe it.

2) Next was to have a small folded bit of towel (I used a shop rag) in a saucer of water. The mould was filled, and as the sprues began to solidify the mould was inverted and the sprueplate was laid on the damp rag for maybe a second and a half, then struck over and the boolits dumped. The appearance of these slugs was an even dull frosting all over. They were also VERY well formed.

3) As in #2 above, but after dumping the base of the mould blocks were dragged across the damp towel, and then refilled. The sprueplate DID NOT get laid on the towel. But was ready to be struck over in the time it took to turn from filling at the furnace to being over the sprue box. When dumped these boolits looked like they'd been cast of mercury. They were mirror bright. For the most part they were well filled out. But they did have more culls then the other 2 ways.

The above shows that mould temp has a very definet effect on how a particular alloy will cast. The alloy temp remained the same (sufficiently for our non-labratory test) only the mould temp was altered. Test #3 with the coolest blocks gave very nice boolits, but there were more culls. All the slugs tossed were due to minor detail items. Maybe 1/4 of the circumfrence of a drive band was rounded, or the edge of the crimp groove.

No major features were affected. This is a BB design and none were rejected due to issues with the base. Large amounts of lead flow to an area maintained a good fill.

A good alloy free of any contaminants like copper, alluminum, iron and zinc (the worst) will cast superb boolits with from 1/2 to 2% tin. Any contaminants will alter how an alloy has to be cast. Adding tin just won't remedy the situtation as it has more to do with how the allow flows and it's fluidity. This is how well it flows into sharp corners and other detail features.

All the difficulties normally associated with poor fillout stem from a contaminated cavity, too cool and alloy, too cool blocks, insufficient venting, or a contaminated alloy.

The best way to find out what you need to do if there is a problem, is to start with clean cavities and begin casting with alloy as hot as your lead pot will provide, and blocks of similar temp. A thermometer is a big help. If you don't get good slugs then, your cavities are contaminated still, or your alloy is in question.

................Buckshot

[Bret4207]

There are a couple other tricks. Get the alloy HOT. Get the mould CLEAN and HOT. Those are the 2 biggies. Some moulds like contact with the dipper or spout, others needs a "pressure pour" with the lead falling into the sprue hole from a distance. That seems to force the alloy into the cavity and provide a good fill out. A big sprue puddle is almost always a good thing IME. Frosted boolits may not look as sexy as shiney ones, but they do tend to be filled out better.

[Bass Ackward]

I'd say the problem has to be common since it affects all his molds.

Thermostat has already been identified. Contaminated mix is another.

What has not been mentioned is the rate of flow into the mold. This is controlled from the spout and the regulator. If the flow rate is is too low (slow), then the spout is cooling the mix too much and the pot temperature has very little effect. All the tin in the world won't correct it.

My high level cut off is 750 degrees with 2% tin. If I can't mold perfect bullets with near zero rejects, then I need to investigate why. The two biggest causes are that I need to improve the venting of my mold which is a one time fix or adjust flow rate. My 20 lb RCBS needs to have the flow rate adjusted about three times per pot as the quantity of lead gets lower.

When I forget to monitor this, my reject rate goes up. If I do follow it, my reject rate is virtually zero.

I have only one mold, which is a single cavity LBT, that simply requires 800 (high side 825) degrees because the 230 grain slug isn't enough heat to keep the big blocks warm. But that's it, everything else works flawlessly at 750 degrees which puts the high side on my thermostat at about 775 degrees for that temp.

[Calamity Jake]

All good info above, one thing that has not been brought up is smoking the cavities, most all
alum. molds need to be smoked to cast a good boolet and some iron molds too, I have a lyman 311041 that will not cast a good boolet if it is not smoked.

[44man]

This is a hard question for me to answer because I get zero rejects from the first to the last boolit, whether 100 or 500.
Only 4 reasons for a bad boolit; contaminated mold, contaminated lead, wrong temperature and a partially plugged ladle or bottom pour spout.
Everyone has given right answers but it still boils down to these reasons.
Keep adding tin and you keep wasting money!

[gregg]

I would like to ask why you reject you bullets. Are they not filling the mold? Do they have voids at the base. Do they have lines running over them? What is the reason you reject your bullets?

You said you use a Lee pot but is it a bottom pour or are you using a ladle?

It might be as simple as your temp isn't high enough even though you have your pot set as high as it will go. Can you borrow a thermometer or another pot to test it out?

I think you have enough tin in it already. Adding more will just raise the cost and not solve the problem.

================================================== ===================

Bottom pour pot. I do like bullshop says and run the lead little off center to the hope of letting
more air out of the cav. It seems to help.

I have a HF dig temp meter. Its going to be couple weeks but going to check temp again. I'm thinking 700 something is as high as the pot goes on high heat? I'm going to try pictures saturday and try to post them.
Bull shop do you fear the damp towel on the sprue plate will warp it?

[jeff223]

when i had poor boolit fill out and alot of rejects all i did was make sure all the mold vent lines were open.i took a scribe and ran it down every one of them.doing this it made them alittle deeper so the mold could vent.the last time i cast some boolits i poured about 500 and i had a hard time finding a reject and i was just using straight wheel weight lead with no tin added.get yourself a magnafine glass to see the vent lines better.with the magnafine glass you will be able to see small burrs on each hole too.make sure you remove those burrs,that will help with boolit drop out and with the small burrs removed the mold can vent .if a burr is blocking a vent line the mold will not vent like it should.

it sure is nice getting A NUMBER ONE boolits from Lee six banger molds now with no tin

[Buckshot]

.............The consensus of answers to the issue of pour quality booits is pretty well revolving around your alloy and as a consequence, mould tempurature. Having to do with this, and not mentioned until Calamity Jake mentioned:

"...................one thing that has not been brought up is smoking the cavities, most all alum. molds need to be smoked to cast a good boolet and some iron molds too, I have a lyman 311041 that will not cast a good boolet if it is not smoked. "

Smoking the cavities slows the heat transfer into the blocks.

I think we've all have answered from the point of conceeding your cavities are clean.

Bass Ackward and 44man:Have both brought up flow:

" What has not been mentioned is the rate of flow into the mold. This is controlled from the spout and the regulator. "

"Only 4 reasons for a bad boolit; contaminated mold, contaminated lead, wrong temperature and a partially plugged ladle or bottom pour spout."

1) Contaminated cavities
2) Contaminated alloy
3) Improper alloy heat, too low (and therefore mould blocks)
4) Poor venting
5) Poor alloy flow (volumn)
6) Alloy delivery to cavity
7) Insufficient sprue puddle

Back to tempurature, Gregg says: " I have a HF dig temp meter. Its going to be couple weeks but going to check temp again. I'm thinking 700 something is as high as the pot goes on high heat?"

It's been so long since I've had my 10lb Lee I don't recall how high it will go. In fact I might not even have had a thermometer then. My Lee 20lb pot when full will maintain a temp of 775-800 degrees. When half full it will run up into the high 900's.

Accepting a couple things, I'm leaning toward insifficient heat as it can look like several other problems. Yet improper flow can also do the same. With a suitable container under the nozzle, lift the delivery handle and while alloy is flowing insert a suitably bent paperclip into the nozzle from below. Work in a circular pattern and up and down. See if it makes a difference to what you're used to seeing.

I don't recall how the 10 lb pot valve is setup, but the 20lb pot's valve sits in a well. Since I pour a lot of 58 cal Minie' boolits, a good alloy stream is very important. Due to that boolit's hollowbase, you have a relatively thin area of the skirts. Heat is withdrawn not only outward into the blocks but also inward into the core pin. A poor delivery won't be able to supply enough hot lead fast enough to reliably cast good skirts.

I ended up drilling out the hole in the spout. At first I was afraid I'd gone a bit too far in opening the hole, but that didn't last long and the first impression was because I just wasn't used to the new volumn. I think the original hole is fine for most boolit's, I think my modification has helped produce more good Minie' boolits.

.................Buckshot

[gregg]

As we all know every mold a law of its own. I have found some molds will not seem to keep up with a fast flow. Its like the venting will not keep up to the flow. Seems like some will take a direct
flow well and some you have to use the bullshop of

"lead stream hit the edge of the chamfer for the sprue hole so it kind of swirls into the cavity."

AND I think lets the base vent better.

Thinking I need more heat. So many good tips here. I have own 3 lee 10lb lead pots First one Mom and Dad gave me to get me off there cooking stove. That one started leaking so Wife gave me a new one. Found the fix is running a screw thru top rim to hold the pot liner up so the valve can seal the opening. So now GF gave me a new pot last Xmas. Both these ladys love casting.
Not before I go I have had trouble with both of these pots. So its not a new problem. I cannot remember wich one I have done the temp test on? Yes I have tried smoking the cavs. No help for me. Have taken a 5/8 bolt . what ever fits a 4.5 grinder cup wire brush and cut the head off of the bolt and turned it down to fit a 1/2 drill and used it to clean the pot liner out of all the crud that builds up there.

[montana_charlie]

I have not figured out what is the correct answer to Greggs question, but almost everybody else has mentioned increasing temperature.

In his opening post, he said...

Have a idea from Harry-O of putting my mold on the lead pot to wait for the sprue to harden? Been hard to keep the mold hot enough waiting for the sprue to harden. Lee 10 lb pot turned on hottest settting BTW. .

If 'waiting for the sprue to harden' takes up as much time as his words indicate, does anybody really believe he is running too cold?
CM

[454PB]

Yes, it seems he has a strange problem. The melt does not get hot enough, yet he has to wait too long for the sprue to harden????

As to Buckshots post on 10 pounder versus 20 pounder Lee pots: I have both AND an RCBS lead thermometer. Both size pots attain the same temperatures, and the thermostat settings even match on both units. Yesterday I was smelting a small batch of dental X-ray backers in one of my Lee 10 pounders. I stuffed it full and went about another project. I checked it about 15 minutes latter and in the subdued lighting, the bottom 1/3 of the pot liner was glowing red.

Re-reading this and all the responses, it's beginning to look like a flow restriction problem, easily cleared as Buckshot mentioned.

Since gregg doesn't own a lead thermometer, the next process of elimination would be to try dipper casting with the same bottom draw pot. That will tell you if it's an alloy or temperature problem rather than flow.