Casting temperature? Help, please!

[patsher]

Hi, everyone![smilie=s:

I'm fairly new to this boolit-casting thing, but have REALLY been enjoying it -- I had no idea it could be such a peaceful thing to do!

My question has to do with the fact that after having cast probably 3K or 4K boolits, I only recently bought an electronic scale and started researching the weights I was producing, and began to suspect that variations in casting temperature might have a lot to do with the wide spread in weights I was seeing.

So. Are there temperature standards for casting? We live at 5000 ft. elevation, and water boils at 196+ degrees here, so does elevation have any significant effect on the temperatures at which I should be casting?

Info: I pour for 38 special, 9 mm, 40 S&W, 45 acp so far. Recently bought a casting thermometer, but have no clear idea at what temp I should be casting.

Thanks for any input you can give me!

Pat

p.s. It's taken me two days to get this question sent, because I keep finding so much info on all the posts. What a great site!

[45&30-30]

Welcome to the site. I have just recently started using a thermometer to cast. I have been casting at 750 to 775 with wheel weight alloy. I go up this high for water dropping the bullets so I get a good sizzle sound when they drop. Generally If I go higher I start to see a lot of coloration in the alloy. Gold, purple, blue... I don't know if bullets are more consistent in weight because of temperature. Someone here will be able to tell you.

Sometimes I have had to base temperature on the alloy, if it seemed to need to be hotter or cooler I changed it. I based it on my results and what the alloy looked like. Consistent fluxing helps to. Of the ones I throw back it is based on visual inspection first. I grab each bullet and look at the base first. If their is the slightest bit of roundness to the edge it goes back. Then I check the rest of the bullet for fill out.Then I sort by weight for rifle. Pistol I don't weigh and just use the visual inspection. Good luck.

[Southern Son]

Pat, Welcome to the forum, this is the place to learn what ever you need to know about casting, swaging, loading, shooting or whatever.

About the casting temperature, I think alloy will make a bigger difference than altitude. Your mold will help you figure out what temperature it likes. I have a Brooks mold that likes 750-775 when I use 20/1. If I am casting with a CBE brass mold and using 50/50 WW/Pb, it seems to like 775-800. There are not any real hard and fast rules for temperature of melt or of mold. Use your thermometer and monitor the temperature of the melt during the casting session. If that fluctuates, then so will your boolit weight. As you find temperatures that work well for the alloy and mold you are using, write them down so you can do it all over again. Others will chime in with thier ideas and what works for them.

[runfiverun]

if your weights are waay wide like 3-4 grains your casting technique is at suspect, if you are talking a grain or maybe two it's fluctuation in alloy temp and mold temp.
look for a mold temp of 350-375 and alloy temp of 700-750.
these temps will change depending on mold size and composition and of course your alloy content.
i have cast boolits with my alloy as low as 625* and as high as 800*
but a hot mold,consistent alloy,and alloy temp,along with an even cadence will produce good results.
something as small as how close to the spout you hold the mold or where the stream hits the sprue hole can make a difference too.

[44man]

Some pots have a wide swing from turn on to shut off and the reverse. Watch the thermometer during pot cycle.
My Lyman was the worst for a wide swing and my Lee seems to be the best.
Best gauge for casting is to look at your boolits. You don't want wrinkles or full frosted. Too hot can drop smaller boolits just like a cold mold.
Adjust for pretty, filled out boolits, just short of frosting and enjoy shooting them. Change the speed you spend filling the mold from boolit to boolit to hold a mold temp range.
Don't go make a sandwich or a cup of coffee between boolits! [smilie=l:
I am guilty of stepping outside to make yellow spots in the snow though. [smilie=s:

[blikseme300]

+1 for what runfiverun wrote



but a hot mold,consistent alloy,and alloy temp,along with an even cadence will produce good results.
something as small as how close to the spout you hold the mold or where the stream hits the sprue hole can make a difference to

The important word here is "consistent".

For quite some time the consistent alloy and alloy temp drove me nuts. The alloy I was using was from recycled WW's and other unknown sources. I have since switched to just purchasing alloy from Rotometals and Missouri Bullet Company. I also invested in building a PID unit to control the alloy casting temp. Results are now where I want it, consistent.

Bliksem

http://bliksemseplek.com/boolits.html

[patsher]

Well, I see there are several things I need to do differently. Yes, I was getting a wide spread of maybe 5 grains, with maybe 75 percent of them within 2 grains. That was after I pulled out all the wrinkled and non-filled-out ones for remelting.

I was getting pretty, well-filled-out boolits most of the time, until the other day when I suddenly started getting wrinkled ones. So I changed to a different mold which was well-smoked and began dropping beautiful boolits again. I looked at the previous one and found some of the smoking had worn off or something because I could see little shiny places here and there. Do these molds need to be re-smoked or something? And if so, how often?

Okay, two more questions: How do you tell the temperature of the mold itself? Do you leave the thermometer in the pot all the time or just check the temp from time to time? And three, what is a PID unit? (Sorry--that's three questions)

[theperfessor]

I'm working on some of these issues. For am explanation of a PID controller you might want to check my post in Casting Equipment titled Dual PID Controller.

[dragonrider]

You don't mention what molds you are using, Aluminum or Steel?? it does matter. I find with a steel mold alloy temps can run about 750, with aluminum I need to run about 850-900.

[Cloudpeak]

Hi, everyone![smilie=s:

My question has to do with the fact that after having cast probably 3K or 4K boolits, I only recently bought an electronic scale and started researching the weights I was producing, and began to suspect that variations in casting temperature might have a lot to do with the wide spread in weights I was seeing.

So. Are there temperature standards for casting? We live at 5000 ft. elevation, and water boils at 196+ degrees here, so does elevation have any significant effect on the temperatures at which I should be casting?

Info: I pour for 38 special, 9 mm, 40 S&W, 45 acp so far. Recently bought a casting thermometer, but have no clear idea at what temp I should be casting.

Thanks for any input you can give me!

Pat

Welcome to Cast Boolits, Pat. Nice to see another Wyoming guy join up. Adds lots of class to the place:smile:

I cast lots of 9mm and 45's and a few 38's. I guess I've cast around 50,000 bullets by now through my Lee 4-20. I've never weighed any bullets and don't own a thermometer. I just let the bullets "speak to me".

One thing I've found to be very helpful is to pre-melt lead in on a hotplate and pour it into my bottom pour. Even if you're ladle casting, melting lead in a separate both will help you keep your casting pot at the proper temp. Dropping cold ingots into the casting pot does not make for a consistent melt temperature. The hotplate is also very useful for pre-heating molds. Once you have the temp. dial "dialed-in" your mold will be up to temp and you'll be able to drop useful bullets right off the bat. You'll also be able to open your sprue cutter with a gloved hand which saves pounding on the sprue cutter.

[Trapshooter]

When I first started casting, I inspected the bullets, then weighed them too. I saw what I thought was an unreasonable weight variation, so looked at a few of the lighter ones under magnification. Most of them had slight rounding on the bands or on the base, instead of good sharp corners. If I looked first with the glass, the weights were a lot more consistent, (but the reject pile was bigger). Now, with the glass and good light, and a bunch more practice, very few are tossed because of extreme weight variations.

Trapshooter

[Greg in Malad]

Pat,
There aren't any set rules on alloy temp. I use the same alloy for almost everything and my casting temp varies from 700 to 850, depending on the size of the bullet. 500 grain bullets cast at a lower temp than 50 grain bullets. The mould material will determine casting temp as well, aluminum uses higher heat than steel. Don't take the thermometer's reading as gospel, I have 2 thermometers and they read 30 degrees apart. I have also found that 6 cavity moulds cast at a lower temp than 2 cavity moulds.
Regarding bullet weight variation, In Veral Smith's book, he advocates casting at high temp, and filling the mould slow, to give trapped air more time to escape. It works for me.

[kingstrider]

Do these molds need to be re-smoked or something? And if so, how often?


You did not mention what type of molds you were running. I use the Lee 6-bangers more than anything else and usually have to resmoke when the boolits start to hang up in the mold, maybe every second or third time I use the mold. My iron molds do not seem to require this as often but then they don't cast hundreds at a time either.

[patsher]

Wow, thanks for the info! I've got a hotplate on my "shopping list", and I'll drag out my magnifying glass, and I'll pay attention to different temperatures when using my 2-cavity molds vs. my 6-bangers.

All my molds are aluminum. So far. (I did what several people had suggested: use 2-cav molds when starting to learn to cast, then 6-bangers later, after I figured out which bullets I liked best). I thought about selling the 2-cav molds, but then my grandson got interested in doing this, so .... LOL.

Pat

[cbrick]

Welcome to Castboolits patsher :cbpour:

Yep, temp will effect the weight of your boolits. The extent that this will effect your shooting depends a lot on the type of shooting you do. For the calibers you mentioned and the range and velocity they are typically shot at a bit of fluctuation in weight isn't nearly as important as say higher velocity, long range match or rifle boolits and not nearly as important as proper boolit fit "your" guns. You must be paying attention as a new caster, most new casters don't pick up on this as quickly.

I shoot mostly long range handgun, I cast clip-on WW at 700 degrees and pre-heat the mold. I don't flux or add anything to the pot until it's at 700 degrees (liquidus temp). The first 8-10 pours are rejects, even though I did pre-heat the mould it's still not at casting temp. Those first pours will be the lightest boolits cast during that session. Eliminating them from the get-go reduces the weight variation of that casting session. I don't weigh all boolits, only about 10-12 from each session. One reason is that these boolits should match closely the weight of previous casting sessions and if they don't I could have a variation in the alloy. I cast with iron moulds at 700 degrees, aluminum moulds and or 22 cal boolits about 725 and HP's at 750.

The purpose of adding tin to your alloy is to minimize oxidation. Tin is effective for this up to about 750 degrees, after that the tin itself oxidizes rapidly. For those that say they cast at 850-900 degrees I hope they aren't wasting money buying tin because what's left of it in their alloy cannot do it's job.

Smoking the mould? An old wives tale. If smoking your moulds nets any real bennefit it is simply covering up some other problem such as a bur or dirty mould etc. You shouldn't need to smoke them at all, keep them clean.

Mould temp can be taken with one of those infrared thermometers. An interesting experiment but not really needed. If your pot temp is correct and your boolits aren't either really shiny or really frosted mould temp is correct. I leave the thermometer in the pot when bottom pouring, when ladle casting it's in the way and I take it out.

Here's an article on alloys that should give you some info to get you started in the right direction: Cast Bullet Alloys (http://www.lasc.us/CastBulletAlloy.htm), for further reading - Cast Bullet Articles of Glen E. Fryxell (http://www.lasc.us/ArticlesFryxell.htm), complete article index (http://www.lasc.us/ArticleIndex.htm). There's enough reading there to keep you busy for awhile. :coffee:

Hope this helps, when more questions come up (and they will) feel free to ask. The only dumb question is the one not asked.

Rick

[lwknight]

Higher altitudes mean thinner air and will cool molds slower than lowlands air. 5000' is not really much different than 1000' I do however notice better fuel economy starting at 5000'.
I think its because my truck is soo unaerodynamic that thinner air means less drag.

[303Guy]

I'm now running my pot with the alloy visibly red hot, whatever that means but with my molds (unconventional) I still have to cast fast to keep the mold hot enough to avoid chill wrinkles (the chill wrinkles are in the form of even bands). I get nice shiney castings but the sprue frosts.

[lwknight]

I think you are casting brass.