Electric Annealing Furnace-For Copper!!!

[Aaron Moss]

Hi All,

I’m looking to build an annealing furnace for copper, I know, the copper guy invading an Iron forum, but the copper guys don’t have a forum…

First of all I do this professionally; I make custom copper products, bronze, brass and such.  I’m looking to make an annealing furnace for copper, primarily bar stock .25 x .75, ¾” and 1” pipe.  The length is the killer; bar stock is typically 36” long.  I’ve been doing it on the BBQ, but I’m looking to get away from that, has some down sides.

So, copper anneals and about 800-1000F so it’s fairly cool, so I was considering using 2 pieces of stove pipe  maybe 10” ID 12” OD 48” long, fill the gap with perlite, pretty straight forward.  I am considering building it VERTICAL and putting an 8” stove burner on the bottom with an Amazon temp controller.  8" burner runs a little over 2000 watts, a little over 6000BTU and they are only $15 with free delivery 4.5 stars too.  The temp controller is about $40, and I've used those before, fairly easy.  and have to put a mesh type material on the bottom so the copper doesn't rest on the element.

 I’ll have to make some steel stands to make best use of the vertical space, maybe some shelves, or something of that nature.  But overall, vertical saves a ton of floor space.  Maybe I’ll base the entire design on a harbor freight dolly!

Might even be able to control the atmosphere better, add argon or something to reduce the oxidation.

So does anyone have any reason it won’t work, or maybe some ideas to go along the way.

Thanks in Advance

Aaron

BTW, I tried to attach a few burnt copper/BBQ pics but it didn't like it.  So if someone knows the trick let me know, prove with photographic evidence you CAN anneal copper on a BBQ.  Covering it in aluminum foil it the key to success!

[Frosty]

Welcome aboard AAron, glad to have you. If you'll put your general location in the header you might be surprised how many of the gang live within visiting distance. 

No flaws in your plan I can see as described. Argon is spendy though you probably have it on hand for mig and tig welding so no big deal. However a little charcoal or even paper in the oven will scavenge oxy just fine but you get smoke. 

I've annealed copper in my gas forge but that was a while ago, no problems though. I was forging some decorative doo dads. It's fun to work under the hammer once you get a handle on how abruptly it work hardens. Fun stuff copper.

 Frosty The Lucky. 

[ThomasPowers]

Vertical ovens tend to have heat stratification if sealed; where will your thermal couple(s) be located?

[Steve Sells]

I would do horizontal to avoid the stratification problem.

[ThomasPowers]

One heating element for a 36+ inch long horizontal furnace?

[Aaron Moss]

I was going to put the thermal couple on the TOP, in the cap area more than likely.  I was going to use 48" length pipe, gives a little headroom.

So it needs a fan or something, like a convection oven.  I can do that, just run a 2" piece of exhaust pipe down the side, I could put a fan in that, motor on the outside of that.  That's a really good point.  It needs to circulate a little.  Make the fan blade out of steel! 

OR

Leave the side pipe un-insulated and it will thermo-syphon form a basic heat engine, but I will lose quite a bit of BTU, not a good idea, but simple.

Yes, one 8" 6k BTU on the bottom, that should be plenty, plus it will be somewhat insulated, 2" of perlite, should be fine.

Still can't upload picks, but my BBQ does it now, we're talking 80-100# at a time.  It's a lot.

 

[Irondragon Forge ClayWorks]

To upload pictures they need to be resized by 50%.

[Aaron Moss]

Hey, That's a winner, Thanks.

There are some tricks, covering with foil is the technical part, poke a few holes in the top let it vent through.  But then, crank it on high for about 3 hours.  I live in a condo, with a very small back yard, so my neighbors must absolutely love it.    For the first 30 minutes it burns everything clean, after that for the next 2.5 hours it just has that really hot grill smell.  Shut it off when done, leave the lid closed, let it cool until morning.

As you can imagine, it's really hard on the grill, and everything has a great metallic taste the next time you use it.

But, it does get the job done and I already have the grill.

Thanks

[ThomasPowers]

Have you looked into buying your stock in annealed condition?

[Aaron Moss]

No, I get the pipe from Home Depot, 10 pieces to get the discount, plus I'm a Vet so that's another 10%, so it's pretty cheap, plus convenient. 

The bar stock, is called "Bus Bar" order that from Industrial Metal Supply, they don't anneal, plus I need to cut it first.  Hard copper is a fairly straight forward to cut.

Plus if it's pre-annealed, you go out an bend it twice and it'll harden up. 

I make a bunch of equipment special for what I do, it's no big deal once I get the basic plan down.  Just need to think about it a little, get the ideas right and then I'll build it over a few weekends.  The way the world is right now, I run hard production for 4 days a week and get the orders out the door, 2 days shop improvement projects (Fri/Sat), Sunday is a little rest, do the computer work, but I don't go to the shop on Sunday.  So once I get the ideas worked out, it just becomes a Fri/Sat project, do it over a few weeks and now the 4 production days are easier.

Been working this way for for a while, I like routine.

Plus with this, I'll figure out a way to control the atmosphere, I'll cook it and it'll come clean as a whistle.  As it sits now I have to spend time running it through the tumbler with ceramic polishing spheres and citric acid.  Let a batch run for 4 hours and it looks polished, but it's annealed and ready to bend.  A pipe cook takes a few batches to clean.  The Bus Bar I run through a bender before I clean it, but it makes one heck of a mess.