Zinc melting techniques

[Cannon Cocker]

l need some ideas for melting zinc.  I have been using a dutch oven with a turkey burner to melt both lead and zinc for years.  Melting lead is a snap especially with a lid on the cast iron dutch oven.  Now I have switched to casting mostly zinc, and it takes forever to melt this way, and uses a lot of propane.  What kind systems do you guys use for melting zinc.  I'd like to be able to quickly melt 25 or more pounds. 

[Zulu]

I use a propane crawfish burner.  I made a pot out of a piece of 10" pipe.  Works great!
Zulu

[Cannon Cocker]

Thanks Zulu.  I'll research and see if a crawfish burner is hotter than my turkey burner. 

If anyone knows of any products that are designed for this I would like to know.  I feel like I've done ok with the jury rig method but would be willing to pay for a good system.

[Victor3]

 I only do lead but I have an old unit somewhat similar to this design...


http://www.ebay.com/itm/Propane-Lead-Melting-Furnace-/130832391609?pt=LH_DefaultDomain_0&hash=item1e7637ddb9


 Mine's all one iron casting except for the burner, valve and sheet metal surrounding the pot. I'm pretty sure zinc could be done in mine since it melts ~30# of lead quickly without running the burner anywhere near max.

[seacoastartillery]

     Several years ago, rampa room artillery (Rick) put up a post on his zinc casting operation on his farm in Virginia.  It looked like a really nice outfit to me.  I'm pretty sure it had a bottom pour device as well.  He used it for volume production as he competed in NSSA Cannon matches.  You might want to PM him for information.

Tracy and Mike

[Cannon Cocker]

Thanks for the info everyone.  I'll pm Rick and look into his old posts.

[KABAR2]

Years ago before my move to Virginia someone gave me a plumbers pot it worked great for casting bullets lead and zinc,
your dutch oven has a flat bottom and way too much surface area to heat and get stuff melted, a lead pot concentrates the heat on a rounded surface and allow the heat to melt the stuff faster.... I would get rid of the dutch oven infact I would break it up so nobody poisons themselves thinking it's food safe.....
Here are a few links from a quick search I did on "plumbers pot"
http://constructionmanuals.tpub.com/14265/css/14265_81.htm
http://www.theantimonyman.com/furnace.htm
http://www.circlemfg.com/plmbers_melting_furnaces.htm

[KABAR2]

     Several years ago, rampa room artillery (Rick) put up a post on his zinc casting operation on his farm in Virginia.  It looked like a really nice outfit to me.  I'm pretty sure it had a bottom pour device as well.  He used it for volume production as he competed in NSSA Cannon matches.  You might want to PM him for information.

Tracy and Mike

T&M
I didn't remember Rick posting anything of melting lead or zinc... so I went through his posts....
I think you are thinking of eyes of death and this thread:
http://www.gboreloaded.com/forums/index.php/topic,198850.msg1099020255.html#msg1099020255
 

[seacoastartillery]

     Allen, you live in Virginia, right?  Why don't you just run over there after work and knock on his door?  Ask to see his zinc melter, take a few pics and then post them later tonight?  It was him, alright.  He had a whole bunch of elongated rifle projos and a some kind of sliding mold where one side opened and the other stayed where it was as the zinc bolt rolled out and down to a collection box.  I think his bolts were either 2.25" or 3.00" dia.  Allen, don't just sit there slack-jawed; get moving!  Chop-chop!    Maybe he showed his zinc melter/caster on someone else's thread?

Tracy and Mike

[Cannon Cocker]

Years ago before my move to Virginia someone gave me a plumbers pot it worked great for casting bullets lead and zinc,
your dutch oven has a flat bottom and way too much surface area to heat and get stuff melted, a lead pot concentrates the heat on a rounded surface and allow the heat to melt the stuff faster.... I would get rid of the dutch oven infact I would break it up so nobody poisons themselves thinking it's food safe.....
Here are a few links from a quick search I did on "plumbers pot"
http://constructionmanuals.tpub.com/14265/css/14265_81.htm
http://www.theantimonyman.com/furnace.htm
http://www.circlemfg.com/plmbers_melting_furnaces.htm

I'm getting some good info here.  I think you're on to something with the shape of the pot.  I also think after studying the plumbers furnaces that the heat shield has a lot to do with containing all that flame that I see going up and around my pot even though it's fairly wide.  I'm impressed with evil eye's rig, but that looks like a little too much to confront.  I'm going to look into the plumbers furnace rigs and try to be done with it.  If I get one, I'll post pics and results.  Thanks for the help.

[GGaskill]

Some of the old plumbers heat sources were gasoline fired.  Gasoline is a higher heat source and probably cheaper for the same heat and more available.

[Double D]

Here is the set up we used to cast at my house.



Home made pot, Metal 5 gallon can  around te burner and pot to shield from wind and hold heat.



This is the turkey burner set up.  Cast Iron pot on the burner and a weed burner for the high heat.

I have pretty much given up doing my own zinc casting.  I have sent my moulds off to Rotometals to have my cannonballs moulded.  They supply new clean metal and charge what I consider a reasonable price for the end product.  Cast zinc with a meltling pot is a lot of work.

 

[cannonmn]

A friend has an automatically temperature-controlled propane melting furnace.  If you want high-quality castings witout voids etc. you keep the casting temp. very constant, I forget what the magic number is.  I had him cast some studded bolts for a 3-groove steel m/l mountain gun and they came out great.

[Zulu]

I had some problems when I was casting lead or zinc.  My crawfish burner worked good with the 10" pipe pot I made. 
The first couple of balls poured into the mold had to go back in the pot because the mold was not hot enough.  Then I could pour about six balls before the mold became too hot.  The propane was going full blast, so I was dumping the balls pretty quickly after pouring.  They are 3" balls.
After about six good ones, when I dumped the ball, it would sag on the concrete.  They needed to be left in the mold longer for cooling before dumping.  But with the propane burning full blast, it is hard to wait for the ball to set up enough to dump.
The mold takes a long time to cool, so i would have to turn off the propane.  I would pour about six good ones a day and just start over next day.
This is my mold with a concrete ball in it.  I don't have pictures of my lead or zinc melting process.
 
Anyone else have the "mold too hot" problem?
Zulu
 

 

[little seacoast]

I use a high output propane burner of the turkey type, works very well . A wind screen will cut your time significantly, the drum from an old washer or dryer works well. I found a round bottomed cast iron 1 gallon pot at a flea market that works well and you can't beat it for cheap.

[rampa room artillery]

seacoast  who we are looking for is artilleryman  he is the one that has a great way to cast zinc as i use a simple 200 lb iron pot and propane burner. takes a while but works great when it gets up to temp.


     Rick bryan

[armorer77]

I haven't done much zinc , but for lead the magic number is 350 degrees .  I drilled my mold for a Lyman pyrometer and watch the temp , too cool wait , I use a hot plate to pre warm the mold , too hot take a break . Ed

[Cannon Cocker]

 Zulu,  I have the same problem with heat control.  I solved the first part by using the weed burner to warm up the mold to what I think is about 4-500, but then eventually the mold gets too hot and they start coming out bad again.  I'ts a constant battle like you said, to get them out quick so they don't heat up the mold, but still leave enough time to solidify.  And the hotter the mold gets, the longer it takes to solidify and the hotter the mold gets....chasing your tail. All this while trying to keep the zinc pot at a good temp as John says.  When you first look at the melt temps of zinc and lead you think...no problem just a lil hotter and I'm in bidness. Taint that easy.  Whole new ball game with zinc. 
 
 I did come up with a good source for zinc I should share though.  When I first started looking I would by from scrap yards.  After my experiences I don't advise this. With all the other temperamental things going on with zinc, having a bunch of dirty, inconsistent, slag topped garbage makes it impossible to get good castings.  So I got some Zamak ingots from a zinc supplier and it eliminated at least some of the problems, but it was really expensive.  Then I got an idea to call an actual user (a big zinc casting mfg) instead of a supplier.  The suppliers don't care about a guy who wants to buy a few hundred pounds which is small potatoes.  So they gouge you if they will sell at all.  Googled zinc die casting and called and spoke to an owner who was willing to sell zamak ingots (18lb segmented) for 25 cents over spot metal prices.  Spot price is 1.10 right now and I paid 1.35 a pound cash for zamac 3.  I was paying 1.00 for scrap crap! The segmented bars are nice. You don't even have to cut them. I just hit the bar over an anvil with the segment hanging over the end and it snaps off.  I might have been lucky to find a guy who would sell to me, but I had a whole list of die casters and this was my first call. 
 
 

[Double D]

Here is one other thing to figure in to the Zinc equation...you can use them over and over again with out having to recast them.  You can't do that with lead.

[GGaskill]

Excessive heat in casting moulds is a long standing problem, even for small arms bullets.  The usual process is to touch the mould against a wet sponge to absorb some of the heat.  For the large moulds we use, I would go with a spray bottle with water in it.  Never so much water as to cause a steam problem and generally under control and cheap.

[Cannon Cocker]

DD,  Yes the reusable factor is usually valid.  We have a lot of baseball sized rock in the berm/backstop we fire into, so they get pretty banged up. Also, I fire into the same area all the time so when I'm digging for them I can find some from previous shoots, as they accumulate in the same spot.  My bolts will go in sometimes 2 to 3 feet so if I shoot 15 shots in a day and dig out at the end, I may sometimes end up with 15 back or on a bad day only find a few.  I've found some of my old designs that I know I haven't shot for years. The pro is that I have a better chance of mining gold, the con is that they collide with each other.  When your talking about $5 and up worth of metal, I'd rather have a good chance of finding something every time than less of a chance of finding them but in good shape.

Gaskill,  Good Idea with cooling the molds off.  You made me think of a time when I did some copper plumbing with a friend who showed me how to wrap wet rags around pipes he didn't want to have heat conducted into while soldering connections.  I think I'll try the spray and the wet rags to see what works best.  Can't believe I didn't think of either of those before, rather than just waiting or quitting. 

[Cannon Cocker]

Here is a picture of the current rig and some of the Zinc (Zamak 3) I bought.

[GLS]

I also use a infrared thermometer ( no touch ) to keep track of the tempuratures.  At least on the surfaces but once you have the correct temp your good to go.  Just point and shoot and you know right away if your to hot and need to cool it down and then when it is just right to open.

[rampa room artillery]

Infrared. No touch therm is good for metal but no good for melted metal as you will only read the surface temp witch is a lot colder then the core temp.

[GGaskill]

Stir the pot just before measuring.

[Victor3]

After about six good ones, when I dumped the ball, it would sag on the concrete.

 I'd suggest not letting the balls fall onto concrete, especially if they're not solidified. Concrete soaks up water like a sponge and there's a chance it will cause a small explosion due to steam if exposed to high heat. Learned that at an early age watching my Dad torch cut steel over concrete.

[Cannon Cocker]

Came up with a solution and one I would recommend to all.  In studying the plumbers furnace, I noticed that although the rig is the same, in that it is a stand that shoots a flame straight up like a turkey/crab burner, it has a heat shield that the pot actually sits in.  With the plumbers furnaces the pot is tapered and rests about half way into the opening.  This allows no  heat to escape around the outside of the pot and also heats the entire bottom half of the pot evenly (I noticed that even with the bottom of the inside of my pot red hot, it was not melting zinc very fast).  I went to Menards on a quest for a heat shield and found a steel reducer that's made for air ducts (about $10).  The original opening was undersized, so I used a grinder with a cutoff blade to carefully enlarge the opening to the point that the iron pot hung half way into the opening.  I would say that it reduced the melting time to about a third, and I didn't have to buy the $160 plumbers furnace.  Also, I emailed the plumbers furnace seller and found that the BTUs on it were 65,000 which is the same as my turkey burner.  I may still get something better some day, but this makes production way faster. 

[VA Rifleman]

Cannon Cocker,
Great topic. I had stopped all cold weather casting due to quality issues.
I may move back to the 2.25" pellets this season.
The more I try to find a better short range design, the more I appreciate the pellet.