Lessons with a scale

[Mike W1]

Don't know how valid statistically these little sessions are going to be but have done 8 or 10 short runs so far and am seeing some consistency in results. 80-100 casts with a Lyman DC 452370 mould each time and separating the bullets by cavity. Bottom pouring with stock steel sprue plate and also aluminum sprue plate alternately. Preheated the mould on a hot plate at 380° F for the the roughly 20 minutes it takes to get the pot up to temperature. Both units PID controlled. Have figured the Avg. weight and then the percentage that are within ± 1 gr. of that weight. Recorded the number of Highs & Lows of that average but only recorded the extremes of each category. There might have been 7 Higher than average and 2 Lower out of say 90 bullets. That would give me a 90% figure of that ± 1 gr variation which is what is recorded. Might not be the best way I suppose but can easily compare success in percentages. What seems apparent to me so far.

1. First cast bullets weigh right in the average per cavity for that session. 100%
2. Average weight seems to vary a couple tenths of a grain from session to session.
3. Bullets cast with the aluminum sprue plate are generally about a grain lighter than with the steel.
4. Better consistency with the Rear Cavity. 95-100 per cent of them are ± 1 grain of average and the Highs and Lows generally are real close.
5. Front cavity bullets have run from 75-92 % in that ± 1 grain spread but the highs and lows extreme are higher.
6. Generally there'll be more heavier bullets than average on that front cavity by sometimes as much as 2 grains.
7. Can't see anything this far proving the aluminum sprue plate does any better than the steel quality wise but sprues drop off easier and can cast just a bit more rapidly. Obviously the aluminum plate doesn't tend to get lead smears as easily either.
8. Have always adjust sprue plates so they will open of their own weight when mould is turned 90° but it is starting to appear than the aluminum ones could be adjusted a bit tighter than that. Have not reached a conclusion on that as of yet.
9. Use beeswax before I pour from the pot to mould. Lower pot is refilled from another up top which also gets that treatment. Would have to think the alloy has been pretty thoroughly mixed by that time but does make me wonder when I get 1 or 2 bullets sometimes that are that 2 grain heavier than average. Don't really think my method is THAT inconsistent but not going to try to separate bullets in order they're cast. Separating by cavity is pain enough.

Thoughts????

 

[JSH]

Do you pour the same cavity first each time?
I used to try and keep some seperate for each cavity for a project some years back. Shortly after that episode of testing multi cavity molds I got one of my first semi customs. That spoiled me.
I have all but quit with the molds made for the masses and went custom and semi custom. I still some variance but not near as much never ran one though. Concept looked good.

I still stir my melt every so often no matter what I am casting.
I have an RCBS pot. On anything over about a 180, I only cast till it is about half full, then refill and heat up to temp, I keep ingots on a hot plate.
Your system should all but eliminate that issue I have.

I had something similar with a 225415 SC mold. If I used my big pot I got ugly bullets. Then when it did start to cast weights were all over the place. I adjusted flow and did a bunch of tinkering to no avail. Dug out my old 10lb drip o matic. Mixed up a batch of alloy and all has been well since.
I still suspect with the big pot just to much pressure and flow of some sort.
Jeff

 

[Rick]

When bottom pouring as the level of lead in the pot goes down the flow and pressure of alloy into the mold also decreases. In addition with any non PID controlled electric pot as the level of alloy in the pot decreases the pot temperature increases, just the nature of the beast.

You can very simply eliminate many of these problems by ladle casting. If you goal is more consistent bullet weights the ladle is your friend.
.

 

[Mike W1]

No offense intended but a ladle isn't in my future. But will keep plugging away until I get something more figured out to improve what I use. So far the only change I've made in my procedure is I don't fill the pot as full as I used to but am still emptying it to about the same level. Think I'll try refilling before I get down that far for one thing. I use a pot above to refill the lower and everything is PID controlled so temperature is really not an issue. Always fill the rear cavity first so possibly that'd be something to reverse at a later time. Maybe I'll have to draft my wife someday and have her stack bullets in the order cast and then weigh them but that's task I'd really rather not get into. BTW, both pots are the 10# ones. Besides I don't even know anyone that shoots well enough to detect a weight variation that small. Certainly not me!

 

[Rally Hess]

If I might ask Mike, if you are using two pots, why fill one with the other? Why not just cast from each pot? I use two 20 lb. Lees and never run out of alloy. I start with two pots at temp and add sprues back to the pot. I'm casting with a thermometer in the pot I'm pouring from and keep track of temperature. If I add back all my sprue to one pot, I just pour from the other pot until the first one gets back to temp. When one pot gets low I refill it and pour from the other. When the second pot is empty the first is back to temp. Do you get a drop in alloy temp pouring from one pot to the next?

 

[Mike W1]

Suppose the reason I run that way might be merely that I've done it that way for years. Works fine for me and takes less than 2 minutes to fill the lower pot which gives me a little break time if nothing else. No temperature loss as they're both PID controlled. Also just casting from one pot slightly minimizes movement to where I dump sprues and bullets.

 

[JSH]

The dual pots I had seen had a linkage hooking both pots together. The top filled the bottom. The top was fed ingots,myths bottom had a consistent level, hopefully keeping a standard flow in that one.

 

[Mike W1]

Have pondered linking the pots, never figured out just how to do it though. Plus I'd envision 2 pots not up to temperature. Always have hot lead doing it this way. But maybe someday have to try that.

 

[KHornet]

For what ever it is worth, I crank my bottom pour RCBS up as high as it will go before
I start casting. I dip the mold in the melt until it comes up with no lead on the outside
before I start casting. I always cast the same cav first. I don't mind a little frost.
Good luck.

Paul

 

[quicksylver]

My 2c....Old lyman furnace ..guess it's suppose to be 10#'s ..usually go for 8#..I don't do large batches..

I've got a thermometer in it I adjust as alloy drops...I also ADJUST THE FEED as the pot drops...

Remember if you are using multi cavity molds the temp of the alloy drops the longer the spigot is open and the longer the drop is..

But this comes from a guy who generally only uses one cavity....(rear preferred)..(boy that doesn't sound good).....

Try letting one cavity flash before you pour the next..you might see quite a bit less in bullet weights...

 

[Mike W1]

I've got to compile my notes on my efforts and probably will go to my thread of awhile back on Scale Observations. My 10# Lees don't have a feed adjustment on them so it has to be "feel" which most of the time I get right. Did recently make a small depth indicator for the inside of the pot and that range keeps me only draining about 4 ingots before I refill. Seems to help a bit with the "feel". Results so far have been 90-98% of bullets from the Rear Cavity are ±1 grain of average and the extremes varying about 0.5 grain outside that. Couldn't detect any improvement by pouring front first instead of back first as I always have done. One session I didn't adjust the sprue cutter tightly enough and that definitely opened the spread up quite a lot. It did however make me suspicious that a better method of holding the sprue cutter down might make an improvement on the front cavity. Somebody posted a picture of the LBT mold with that little spring deal on it which is something I'd like to copy if I could figure out where to get a spring on that order. Can't imagine where to get something like that to try though.

 

[fiver]

I have used a couple of molds that have a stop screw at the back.
the screw has a head that the plate slides under.
once the front and rear screw are adjusted the plate lies dead flat and with the same tension on both ends every time the mold is closed.

 

[Kevin Stenberg]

Mike have you read Goodsteel's thread on consistent casting on the CB forum? After I read and started using his methods for consistency my bullet weight variation dramatically dropped.

 

[KHornet]

I consider all molds to be female, and not necessarily consistent from one casting
session to another. To many variables to consider. Ambient temps, humidity, mood
of caster, variables of the melt, etc.etc.etc. That said, as long as each batch of whatever
I cast shoots to close to the same point of impact, I am satisfied. Then again, I am by
no means as tech oriented as many on this forum.

Paul

 

[Mike W1]

I have used a couple of molds that have a stop screw at the back.
the screw has a head that the plate slides under.
once the front and rear screw are adjusted the plate lies dead flat and with the same tension on both ends every time the mold is closed.

This concept sounds interesting but I can't picture it in my head. Wouldn't happen to have a photo of it by chance?

 

[Mike W1]

Mike have you read Goodsteel's thread on consistent casting on the CB forum? After I read and started using his methods for consistency my bullet weight variation dramatically dropped.

Tried reading it once and "didn't soak" in. Guess that'd be a good rainy day project to give it another shot.

 

[300BLK]

I learned my lesson with a scale 20 years ago. Once I started ladle casting I never considered bottom pouring again. Both of my 20# and my 10# are plugged and linkage removed.

 

[fiver]

T----T
it's like this.
you can actually flip the plate around and it works either direction on the mold.
both screws have set screws in from the side of the mold to lock them in place.
you just run a wave washer on the swing/pivot screw.
the plate has a notch cut in it to swing in place under the back screw.

 

[Mike W1]

I learned my lesson with a scale 20 years ago. Once I started ladle casting I never considered bottom pouring again. Both of my 20# and my 10# are plugged and linkage removed.

Good for you. And that helped this thread just how?????

 

[Mike W1]

T----T
it's like this.
you can actually flip the plate around and it works either direction on the mold.
both screws have set screws in from the side of the mold to lock them in place.
you just run a wave washer on the swing/pivot screw.
the plate has a notch cut in it to swing in place under the back screw.

Thanks. Was kind of thinking there's got to be a slot in there somehow. Think I'll have to give that a try some of these days.