MTFCA Forum

It is time to put the brass trim on the firewall. How to bend the pictured sold brass half oval at a 90 degree? I have read several places to do not heat it that it will break. I am thinking of just putting it into a vise and bending it, will that work? Is there a better way?

I think you would be better off cutting it and mitering the ends.

Cut it, miter the ends, and silver solder it.
The joint will be undetectable if you do a good job fitting it.
A friend of mine is a jeweler, and I asked him to repair some cracks in some brass lamps. The first thing he did was run a jeweler's saw down each crack, through the crack and into the parent metal. Then he silver soldered the gap. When he was done, he polished it, and I couldn't even see where the repairs had been done.
So now I have a goal to shoot for.

Older post on ways of doing it cold, one-piece , with notching the underside for the 90 degree bends.

One used a mill, the other hand tools.

http://www.mtfca.com/discus/messages/17 ... 1320824601

Brass becomes brittle at low red heat. Some alloys work well cold, others need to be annealed to work cold, sometimes several times depending on what you're trying to do. Good info here on this particular problem ! Good luck, we learn by doing !

Notching the underside of flat brass stock and then bending it is not the same as notching half oval stock.

You can easily notch flat stock as the depth of the notch would be uniform across the piece.

However, with half oval, you would need to vary the depth of the notch and, even if you had the talent to vary the depth, I don't believe the corner would be nice and crisp after you bent the piece 90 degrees.

Frankly, I would cut the half oval stock, miter the ends, drill countersunk holes in the resulting trim and attach it with oval-head screws to the firewall. I wouldn't silver solder it. The joint should be snug enough without needing to solder it.

Use a Cut off wheel from the back side carefully removing the area for a 90 degree bend, heat and cool about 4 to 5 times, bend to your liking. Polish to perfection! DONE!

Hank

The shallow U shaped capping is easy to bend by by filing a V in the legs of the U and pulling the strip around. This technique is fraught with difficulty with solid crescent shaped material. I'd be more inclined to radius the top corners of the wooden firewall so the moulding can be drawn around it.

Allan from down under.

So I don't have a miter box but I do have a cut off wheel. I figured if I mess it up I would be able to salvage it and it WORKED! Looks really good too. Thanks for the tip. I did the flat screws on top and the round screws on the sides.

Henry K. Lee wrote: ↑

Sat Sep 04, 2021 4:15 pm

Use a Cut off wheel from the back side carefully removing the area for a 90 degree bend, heat and cool about 4 to 5 times, bend to your liking. Polish to perfection! DONE!

Hank

Very Nice Job!

Hank

Looks great. Wondering if you used heat or just cold bent it with that dead blow mallet?
Super looking.

Nice work. Thanks for sharing your experience with this project.

DanTreace wrote: ↑

Sun Sep 05, 2021 10:34 am

Looks great. Wondering if you used heat or just cold bent it with that dead blow mallet?
Super looking.

How bout a description of how you did it?
Inquiring minds want to know.

You don't want to bend brass while hot. Heating and cooling it will anneal it so that it can be bent cold without cracking.
The process of rolling the shape causes the brass to work harden, that's why you want to anneal it prior to bending. Heating it to a dull red and air cooling will anneal it. Best to heat it in a darkened area so you can easily see the color.

Just a guess, but suspect the new piece of brass half round stock was already in a soft annealed condition to start with. Most pieces like normally are soft, and bend some what easy.

I heated it cooled it 3 times before bending with a MAPP gas torch. I never saw it turn red. I just got it 'real hot'. I notched it once, bent the two parts together until they kissed then notched again to get to 90 degrees.