Tube Bending
To bend tubing it needs to be filled with some material that will help keep the shape of tubing round as it is bent.
Pitch or soap and water mixture are a couple of options. The soap/water controls the freezing so that the tubing does not collapse. The formula is three parts dawn soap to one part water. AND it must be frozen to -80 Fahrenheit. Dry ice will get you down to about -120 F; anything lower and you'll need liquid nitrogen.
When using pitch, the small end of the tube is plugged. The pitch is heated and poured in? Bending can commence after it hardens. Once the bending is done, the pitch is reheated with the torch and cooked out.
Sand is another option. If it is tightly packed (and both ends of the tube tightly sealed) it should keep the tubing stable to prevent kinks.
Another option is a special low melting-point alloy called Cerrobend. Cerrobend is hard to bend.
Lead is another option, but it is very hard to bend.
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Tube Bending
If the jig is highly polished, it can manage without anything in-between. Bit a thin layer of felt, leather will do. Cork could tend to break when it is not supposed to break...
Inside, I still use lead, or rather a metal called easy bend. But it contains lead as well. If the melting in and melting out goes on in free air, or with proper exhaust from the melting pot, it is not a big problem.
On raw brass instruments the lead can be prevented from sticking to the surface if you draw a cloth trough the tube , the cloth being wet with Vaseline oil.
When the tube is heated by the lead, it will smoke a lot, and oil remains eventually catch fine, so beware. Another reason for doing it in the open air.
With silver plated instruments, there is a higher risk of melting the lead onto the surface. Use a thicker oil and use as little heat as possible for melting in and out the lead.
I suspected that the cork would break too. Felt sounds like a good idea.
Is there a reason you choose easy-bend over pitch? Or is it just that it is what you are used to using?
Reply #4 - Feb 19th, 2006,
I use lead or easy bend because i have got used to it. And have sufficient air exchange in my workshop for using it without danger.
If the jig is highly polished, it can manage without anything in-between. Bit a thin layer of felt, leather will do. Cork could tend to break when it is not supposed to break...
Inside, I still use lead, or rather a metal called easy bend. But it contains lead as well. If the melting in and melting out goes on in free air, or with proper exhaust from the melting pot, it is not a big problem.
On raw brass instruments the lead can be prevented from sticking to the surface if you draw a cloth trough the tube , the cloth being wet with Vaseline oil.
When the tube is heated by the lead, it will smoke a lot, and oil remains eventually catch fine, so beware. Another reason for doing it in the open air.
With silver plated instruments, there is a higher risk of melting the lead onto the surface. Use a thicker oil and use as little heat as possible for melting in and out the lead.
I suspected that the cork would break too. Felt sounds like a good idea.
Is there a reason you choose easy-bend over pitch? Or is it just that it is what you are used to using?
Reply #4 - Feb 19th, 2006,
I use lead or easy bend because i have got used to it. And have sufficient air exchange in my workshop for using it without danger.