cello bending iron

[ravenhome777]

Hello,

I am trying to cast a very large piece of copper into a cello bending iron. (Well, in the end it will be a large piece of copper. Currently it's just scrap.) I have made a form out of refractory cement for the bending iron. Now what I'm planning to do is make a forge out of old bricks, and coat the bricks with cement to keep the heat in. I think it will look a little bit like an igloo when I'm done. The base of the forge is a very large piece of granite. I'm hoping granite will not crack under the heat. I'm planning on leaving two small entrances at the bottom of the forge to blow air into from a leaf blower. I was also thinking about making two additional openings for propane torches. Originally, I was thinking that I would feed in charcoal through the top, and then put a metal car hood on top of the forge to keep in the heat. The car hood would have a hole in it to let the heat out, but I'm not sure if this will melt. Maybe I should make a cover out of refractory cement?

I was originally thinking that I would heat the forge with charcoal, but I began to become concerned that it would not get hot enough to melt the copper and tin. This is a LARGE amount of copper to melt. So then I began thinking that I might need to use coal to heat the forge. I think coal might be the only material hot enough to get the copper to melt. Then I began to worry that the refractory cement form might crack. I double reinforced it with cement and it's within a large steel pot, so it should have a fighting chance at least.

I'll post some pictures tomorrow because I think my description may be lacking clarity.

Anyway, I was hoping to get this done right the first time around, because I may only have one shot at this due to the cost of the materials (and time). I was hoping to get some advice from the experts.  :-)   All help/advice is much appreciated. Thank you kindly!

Edited April 26, 2018 by Mod34
Moved to proper section

[Steve Sells]

Is your life insurance paid up ? it needs to be if you are doing this with out any training or any other casting experience, as it seems you are as you didnt even mention degassing

[JHCC]

Welcome to IFI! If you haven't yet, please READ THIS FIRST!!!

I'm no casting expert by any means, but when I worked in the violin repair shop, the bending iron we used was made from aluminum. Any particular reason you wanted to use copper, and wouldn't it be easier (and safer!) to buy a chunk of copper rod (or aluminum, for that matter) and file it into shape?

[ThomasPowers]

Real charcoal can get hot enough to melt steel; briquettes are mainly NOT charcoal and should be avoided----(Why won't an item engineered to burn slowly at a fairly low temperature not burn hot????)

Molten metal is actually much more dangerous than steel that may be even hotter but is still a solid.  Reading your description I feel you are very likely to have a catastrophic accident as it appears you have no experience with melting and casting metal.  If you want to go forward LEARN FROM SOMEONE WHO KNOWS WHAT THEY ARE DOING!  IF you are trying to save money remember the proper safety gear will cost quite a bit.  Trying it without the proper safety gear and education in foundrywork you might bankrupt your family paying hospital bills if you are in the USA.

I learned casting in an "out of hours" class taught at the Fine Arts Department of a local College. The class fee has payed for itself 100 times over!

BTW alloyavenue.com, (used to be backyardmetalcasting.com), might be a better place to start learning some of the necessary things to do this---including that Copper is a pain to cast as it's affinity for oxygen is so high---see fluxing and degassing.

Probably MUCH cheaper and faster to find a basement machinist to machine one from billet.

[JHCC]

10 minutes ago, ThomasPowers said:

Probably MUCH cheaper and faster to find a basement machinist to machine one from billet.

Or simply buy one. A decent bending iron can be had for under $200, and a copper billet could easily cost that. Aluminum would be cheaper and would still work, but either way you'd still have to figure out the heating system.

[Frosty]

Don't try this. The list of things you pretty obviously don't know about casting let alone casting a high temperature metal is too long for me to go into and I'm not a caster. Please hire it out, take some classes, just buy a cello bender, ANYTHING BUT try this with as little knowledge as you have. 

This is about as trivial a project as hot wiring a F 18 and taking it for a joy ride.

Frosty The Lucky.

[ravenhome777]

I'm not going to be pouring the metal. The metal will stay in the concrete form which is the correct shape for the bending iron. The metal will melt inside the form, and I will never touch it or interact with it until it is cold. I do not see a high level of danger here.

To summarize, I will put the scrap copper and brass into the concrete mold. Then I will build a beehive shaped forge of bricks around the concrete mold. The bricks will then be covered by a layer of concrete. There will be two air inlets in the bottom of the forge to blow air into from two leaf blowers. I will pack the inside cavity of the beehive forge with coal or charcoal. Ignite the coal or charcoal. Turn on the two leaf blowers for air intake. Let it burn for 5-6 hours. Once the burn is done. I'll leave it be for an entire day for it to cool off. Disassemble the forge the following day when everything is cooled down. See if the metal within the concrete form has melted.

Seems pretty safe to me. I'm not planning on taking the form out of the forge while it is molten metal and then try to pour it into something. I agree. That would be dangerous.

[JHCC]

So what you’re thinking is a combination of crucible (container for melting the metal) and mold (container for giving shape to the molten metal and holding it as it cools), yes?

I’ll leave it to those with more knowledge of casting to say whether or not this is a good idea or what kind of results one could expect, but even if it might work, you still haven’t answered a key question: why bother? Why go to the time, trouble, and expense of making such an item when you could buy a perfectly serviceable bending iron for less than you’ll spend on this casting project?

[Smoggy]

You are taking a number of different processes from differing aspects of casting different materials and cobbling them together and expecting them to work. I sincerely hope they do not for the simple reason that you are also introducing the potential for a number of potentially lethal situations which you could not control even if you understood it. Moisture entrapment being the obvious candidate.

I can make a cello bending iron from many materials, tinned steel, copper, brass, aluminium without the need to cast anything. My limited woodworking skills and knowledge have allowed me not only to bend substansial timbers for boatbuilding but also thin strip when I've had my Luthering hat on. (guitars, banjos, mandolins and drums) by making a makeshift bending frames and jigs, usually from......scrap wood!

[JHCC]

Yes, the "But why?" question does need to be addressed. In the words of Chris Rock, "Just because you can do it doesn't mean it's to be done!"

[JustAnotherViking]

Is 'to see if I can' or 'for fun' a suitable answer?

I ended up buying an anvil, new shed, forge materials, etc, etc, all because I wanted a draw knife for some basic wood-working.... to date, it is the most expensive tool I own due to the investment in tools, materials, and time before I actually made one 

[Steve Sells]

your comment of "I dont see anything dangerous "is proof you are being foolish. Just wait for your concrete to explode then repeat that to the EMTs

  I give up, go ahead and kill yourself, we cant seem to stop you

[JHCC]

16 minutes ago, JustAnotherViking said:

Is 'to see if I can' or 'for fun' a suitable answer?

That's absolutely a suitable answer -- if indeed it's the answer. If the answer is "because I need a bending iron", then we need to talk.

10 minutes ago, Steve Sells said:

Just wait for your concrete to explode then repeat that to the EMTs

He did say "refractory cement" in his OP. If that's what he has in mind rather than concrete made with portland cement, the explosive issue may at least be mitigated (apart from whether or not refractory cement is an appropriate crucible/mold material, which I doubt).

[Steve Sells]

He  said concrete, so he is accountable for that

[JHCC]

And not merely in the abstract.

[Frosty]

He's said concrete a couple times. My last suggestion is you buy one of those medalert necklaces, one that calls EMS if you go horizontal quickly, you probably won't be able to dial 911 for thrashing around on fire.

Do this a couple hundred feet from flammable materials.

1 hour ago, Steve Sells said:

He  said concrete, so he is accountable for that

Accountable for all of it.

 

[ThomasPowers]

Remember these forums are see around the world by folks like the feckless teenagers all the way to renowned experts in the craft.  Only takes one guy thinking "I can use concrete in the forge!" to ruin a discussion....Frankly if it was my post I wouldn't mind a moderator correcting that to "refractory" cause I had had a cerebral glitch...(also doing things DANGEROUSLY wrong tends to keep folks of reputation from wanting to help you...)

[Charles R. Stevens]

I for one appreciate moderators coming along and fixing the worst of my brain lapses....

y’all have seen what happens wen my spelling and adaptive text get to gether!

[Steve Sells]

I just got told off for warning this guy that he is going to kill himself   so I edited my post to make it clearer since it seems to have been ambiguous and could be taken in many ways

He also said I need to explain why its dangerous. SO....

 

As little as ravenhome777 pays attention to wording  (maybe he did use concrete we dont know what he used), 

Casting with out training (doesnt know the potential dangers)

Unsafe practices (thinks he can bypass centuries of learned  safety practices to make it easier for him)

Dual leaf blowers, coal AND propane for heat ?

thinking his idea is harmless...(Concrete can explode in a forge at casting temperatures)

Where do we start?   I said he needed training before casting,  if that is too hard to understand  then there is no hope for him

 

,

[JHCC]

Building a fire on top of granite can be an issue as well.

[CMS3900]

How about we ask the OP to clarify, since he has only responded once to the original post.

Do you have any previous casting experience?

What exactly is the refractory being used ie - the brand name.

Standard concrete mixes trap moisture inside and when heated evaporate the moisture which then cannot escape, causing it to spall or explode. If you post your location in your profile someone might be able to give you some local sources or places to get help or instruction on a project like this.

Casting seems to be a taboo subject on IFI because the danger is real and high, to life and property.  Searching and reading the past casting threads is helpful. Also there are casting specific forums on the web that might give you additional knowledge on the subject.

[Frosty]

Right you are John, he did say refractory cement so maybe he won't get splashed with molten copper  thrown by exploding concrete. Rereading the OP has me thinking this is such a bad idea the authorities should get involved. I can't list everything wrong, long winded as I am. Steam exfoliation of granite has killed people, many people in a couple cases. 

We should move this thread to the prayer section he doesn't have one as it stands. I'm hoping his parents have put a stop to this project.

Frosty The Lucky.

[Glenn]

14 hours ago, CMS3900 said:

Casting seems to be a taboo subject on IFI because the danger is real and high, to life and property. 

Not taboo, it is that we are a blacksmithing site. Casting is a form of metalworking, and has it's own set of dangers that are very real. We do not feel that a person should just build a fire, melt some metal, and pout it in a mold without being warned that it is an unforgiving process. Without knowing the dangers, the individual can be in for a lifetime of hurt.Things can and do go wrong even for the experts.

[John in Oly, WA]

Aside from all the dangers pointed out, he's planning on using his mold for the crucible. Even if he has his copper in bead form, there's a lot of air between those pieces. So unless he's built up the mold with a large funnel top, I don't see him getting enough copper in the mold to get a successful cast. Not to mention little details like fluxing and skimming the dross.

[Frosty]

I just don't want to see him in the news. Casting is a terrific craft but it requires education and sequential practice. 

Frosty The Lucky.