Bad Joo Joo. I think???

[mustanggt]

I'm at my wits end with my casting. I have been doing really well with my casting, no issues to deal with till now. I have a BACO Creedmoor mould that cast excellent boolits till now. Also a new BACO Money boolit. No matter how hot the melt or mould 700-800, the bases don't fill out and are wrinkled. Melt is 20-1 clean alloy from rotometals, I've fluxed and fluxed and fluxed, cleaned and cleaned and cleaned the moulds, pot ladle. I changed out the alloy and still am having the problem. I preheat the moulds on a hot plate. I gave up after two hours yesterday and two hours today. When the pot cooled it looked like the desert after a rain and it has all dried up and had holes and fissures running through it, not the smooth surface I've always gotten. I decided to move on to another pot and a lyman 44 mould and an rcbs 357 mould. I had problems there too. I was casting along happy to finally get something for my efforts and all of a sudden one of the cavities in the rcbs mould the bases wouldn't fill out either. Front cavity made beautiful bullets as usual as well as the back one then all of a sudden the back one wouldn't fill out to save my butt. I'm doing everything like I always do the only variable is the Money bullet and I can't see that being the problem. The only thing I can think of is I accidently touched the ladle to a towel not made of cotton and some of it melted on it so naturally I cleaned it real well even sanding it as it left some residue on it that took some elbow grease. Could it have been the culprit? By the way I only ladle the big bullets from one pot and bottom pour the rest from another pot. Hope I gave enough info. Thanks

[JIMinPHX]

What do you lube your mold with & how much do you use?

[chris in va]

I like to approach problems by elimination.

Think back to what point everything changed. What did you do differently? Alloy, mold, procedures the same?

Might be that towel melting to the ladle, or something else the other guys can suggest. I've only been using Lee molds, but every time I get wrinkles, it's because the mold isn't up to temp. Even if my WW alloy is on the cool side, it still makes great boolits.

[Harter66]

I've been afraid to try to pour. Our temps have been all over 1 day last week was 22/36 today is to be 40/61.

I've had my own run of bad luck/joo joo/karma(?)of late myself.

I'd bet its the outside temps giving you fits,or different air movement around your work area. Both would give you cold spots it happeneds to me every time we get a due east low instead of the usual from northwest to southeast . The wind blows from the wrong way and the air swirls right up under my pot and across my molds its a pia to keep it all hot. I'd even be suspect of a cold window if your outside temps are more than say 55* colder than inside. Even w/double pains.

My .02.

[home in oz]

sounds too cold

[Rocky Raab]

Always keep your joo-joo in a cool dry place, out of direct sunlight.



(Sorry. I couldn't resist.)

[JSnover]

700-800 is minimal for me (45-70, 500gr). I get better results at 800-900.

[onondaga]

I can give you some tips that should help, but in general, I find that people who heat bullet alloys to 800 degrees for any reason just don't get it or are too stubborn to believe they could possibly be incorrect. First, if you are casting outdoors or in an unheated area where the temperature is near freezing or lower, wait till a much warmer day.

If you brought your alloy up to 800 and didn't immediately bring it down a couple hundred degrees and re- flux the tin back into the alloy, you ruined your alloy unless you wanted to cast with no tin in it. The tin will stay on the top of overheated alloy and continually oxidize at a rapid rate.. The popular sawdust on top of your melt does nothing to keep the tin in your alloy unless you first have the metal at a temp that does not separate the tin from your alloy and you have properly fluxed the alloy below the separation temperature of tin.

Alloys with no tin don't fill out molds very well even if casting technique is perfect. If you have to use your no tin alloy you will need to do something to vent your mold a lot more than the manufacturer normally does and you might get it to work. That could involve loosening your sprue plate or beveling the top of your mold blocks a few thousands of an inch so they form a small V channel at the top to let air out under a tight sprue plate. Pressure casting may help, ladle casting may help. bottom pour casting will be difficult with that alloy unless your pour spout is immaculate and slightly enlarged and you use the maximum flow rate with a full pot.

You could fix your alloy by adding 2 -3 % tin and fluxing at a temp that does not separate the tin from it. Tin lowers the temperature needed to melt bullet alloys and increases the flow quality of the alloy.Learn how to cast at more moderate temperatures with tin in your alloy and try to isolate your problems one at a time instead of cranking up the temperatures to extremes. 675 degrees is a reasonable maximum. If that doesn't work for you something else is very wrong.

Excellent casting is an harmonious balance of metallurgy, thermodynamics and physics. Pushing one aspect of those three aspects of balance to get acceptable bullets is only getting acceptable bullets, not excellent bullets.

Gary

[mdi]

Walk away for a day or two. Then start from the beginning. Clean the mold as if it were new and you just got it; a complete and thourough cleaning. If you use any lube on your molds, wait untill after you try it again. Empty your pot and scrub/wire brush all the junk out of it. Go with virgin alloy. Double check your temps and method. There's a lot of "mebbes" that could apply, but you need to have some "known good" factors (you know you mold is good, you know your alloy is good, etc)

When I run into a wall I use this method and most of the time it works for me...

[dragonrider]

Check your vent lines, may be blocked.

[RobS]

I find that people who heat bullet alloys to 800 degrees for any reason just don't get it. Gary

Well I guess Veral at LBT just “doesn't get it” as he tests his molds out at 800 degrees. He does say that it would be better for cooler alloy if you continue to read on though but if not then.......................Post #2 on the page

http://www.go2gbo.com/forums/index.php?topic=197264.0

Now I'm not saying one way or the other and your comments do have good merit, but coming across in the manner that you do really does make a whole lot of good folks look like incompetent fools when they simply are not.

[onondaga]

I didn't say foolish at all. I hope I got his attention although. He sure is asking for help and I definitely want to learn him away from 800 degrees. I have been called on for telling people that they have ruined their alloy before. I know that is hard to take and accept, but I hope it can be taken as a learning experience and not an insult. I am sure the man wants to make good boolits. He said he got the alloy from Rotometals, they are not cheap. I bet a call to Roto's metallurgist in charge saying something like-- I might have overheated your alloy, at what temperature does the tin separate from this particular alloy? Possibly a more authoritative answer than mine would help.

I have looked at samples of cast over heated alloys in an electron microscope to verify to customers that they have overheated alloys when I was a casting analyst for a precious metal manufacturer in their education department. The structure difference is evident. This is the same with lead alloys and easy to prove--but you need a metallurgy department with an electron microscope as I had, but I am retired now.

Gary

[RobS]

Gary:
Its the approach in which you deliver that makes people feel foolish or makes them feel offended. Reconstructing the way you write in a more settle means will relay a much better approach to what you hope or want others to understand.

[felix]

I thought Gary did a very good job, Rob. In my opinion, it is more offensive to quote others in your defense, unless the 'others' are also active participants in the conversation (thread). ... felix

[geargnasher]

Baahhh. Here we go again.

Gary, your'e spot on with everything I know about boolit casting and non-ferrous metallurgy. I have been beating this same drum for some time now and if people want to get butt-hurt, so be it. Maybe they'll learn something. I found nothing offensive at all in your posts, only your desire to help out and share your valuble knowledge.

Binary lead/tin alloys are most particularly susceptable (sp) to tin "burnout" from alloy overtemp because there is no antimony present to form the tin/antimony intermetallic. That intermetallic somewhat preserves the tin, but anything over 750* still causes it to dross out. 20:1 will dross out most of the tin in a matter of a few minutes at 800*, I know this very well. I was miffed until I read the Metals Handbook and looked at some phase charts for Pb/Sn/Sb alloys, then the old lightbulb came on. My casting temps went way down (75-125* over full liquidus) and I'm much happier, in fact I can drain a 20-lb pot in an hour and barely have any dross form at all on the surface.

Gear

[mpmarty]

Heck I pour at 800 degrees with my LEE molds all the time and have no problems. Boolits fall free and shine as long as I touch the wet towel with the mold often enough to keep the mold temperature down. I cast 175gr 30 cal and 350 - 450 gr 45/70 stuff as well as 230gr 45acp.

[montana_charlie]

Gary:
Its the approach in which you deliver that makes people feel foolish or makes them feel offended. Reconstructing the way you write in a more settle means will relay a much better approach to what you hope or want others to understand.

Making a person feel foolish, or slightly offended, will often get his attention when 'false kindness' won't.

If the person admitted to a method, or routine, which is considered to be 'unhelpful', making a point of berating that part of the procedure is sure to get the questioner to thinking about it.
If you are sure you are right (and Gary seems to be sure) then say it straight out...without the kind of 'buttering' this PC society has made people think they deserve.

CM

[geargnasher]

Felix, you posted while I was typing, my fingers are cold this morning!

Gary, there is a "backyard metallurgy" method for proving how much tin you've lost from overheating a binary alloy, skim off all the dross that formed after the last good flux, then remelt the dross into a solid form with a propane torch and reduce it as much as possible with candle wax (I used a deep spoon for this), then use the water-displacement method to determine specific gravity of the metal, compare to known specific gravities of the two metals in question, and do the math to figure the proportions. I've found as much as 90% tin in dross from binary alloy.

CM, it's never my intent to give information in an insulting manner, but raw facts and data delivered as such are often lacking "touchy-feelie" qualites.

Gear

[RobS]

Well people, what I am trying to covey here is that by saying a person doesn’t have a clue if they cast at 800 degrees is absurd. I stated that Gary’s post had good merit, never said it didn’t.

Casting at 800 degrees, and many people do, I guess produce boolits which are junk if I understand the logic of this conversation……………This of course is not the case as there are different alloys as well as pure lead which require heat for proper mold fill out...... Anyway, people cast at different temps for different reasons, whatever the case, but to make a statement that if a person doesn't cast at a lower temp that they "just don't get it" is narrow minded and flat out not right. I will not be talked out of the fact that making statements as such isn’t right and that my thought in the matter would place me in the back seat in regards.

Felix, I was referencing Veral’s Post and the thread on the other forum in which it came from as the member there was having a similar experience with mold fill out as it relates to alloy temp/mold temp. I never once quoted anything he wrote. I left the link here on this forum for others here at CB to read for themselves. Referencing Veral is not offensive in the least as it pertains to this thread with similar content. Think of all the research that has been done with reference to other peoples work in the field.

montana charlie, I don't give false kindness nor do I post negative comments either. It should be about providing help to people who are not of teenager mindset (for the most part members here are not like this). The OP is definitely not of such nature, he does not need to feel foolish or be slighly offended in order to learn. Most people here don't require it either and will learn just fine without the negative orientation.

[JIMinPHX]

I generally don't cast anywhere near 800 unless I am using pure lead. For something like drive key shotgun slugs, I can't seem to get good results much below that temperature & I might go to 825 or even a hair above that if it seems to help. I sometimes cast pure lead round balls around that temperature too. Most of my other casting is done in the 650-720 range, depending on the mold & the alloy. I do notice a goldish skin develop on the surface of the melt if I run the temperature of a rich alloy much more than 50 or 75 degrees above where I need it to be to cast well. I believe that goldish color = lost tin. In general, if your boolits aren't frosty looking yet, you are not even close to being too hot. Even frosty is OK, but then you need to start watching that you don't go much higher.

At least that's my humble opinion in simple terms from what I have seen so far in what casting I have done to date.