I think this is the right forum

[DonRecardo]

At least I hope its the right forum.
A short while back on a forum ( hopefully this one) someone
posted a way of making a tool for turning round copper wire into D shaped wire
by drawing it through like a draw plate, but if I remember right this draw plate was made in 2 pieces.
One part has a hole drilled in it which was then milled down to leave just a semi circle and the other part was flat
and was bolted across the bottom of the semi circle to make the D shape

Was it on this forum that I saw it and if so can anyone point me to it please?

Cheers
Don

[Frank S]

I don't remember one in the past 1 1/2 years but thyat is no tto say that someone hasn't done what you are thinking about
But I think if I were wanting to reform copper wire from round to a "D" shape I would look for an older wire feed drive unit from a mig welder one of the industrial use size with 4 roller drive . machine the first 2 rollers to the diameter of the wire with 1 of them only slightly flattening the second pair would be shaped to the final contour of the desired shape and size. in any case if this is to be used as magnetic or electrical wire it will have to be re shellacked
If you are wanting to just re form the ends or short sections of wire then you would only need to make a pair of swedging dies one with a grove the desired diameter of the wire used about 60% in depth of the diameter the other only being flat

[DonRecardo]

I don't remember one in the past 1 1/2 years but thyat is no tto say that someone hasn't done what you are thinking about
But I think if I were wanting to reform copper wire from round to a "D" shape I would look for an older wire feed drive unit from a mig welder one of the industrial use size with 4 roller drive . machine the first 2 rollers to the diameter of the wire with 1 of them only slightly flattening the second pair would be shaped to the final contour of the desired shape and size. in any case if this is to be used as magnetic or electrical wire it will have to be re shellacked
If you are wanting to just re form the ends or short sections of wire then you would only need to make a pair of swedging dies one with a grove the desired diameter of the wire used about 60% in depth of the diameter the other only being flat

Thanks for replying, I wonder where it was I saw it ?
I want to make the D section to go around the edge of a model loco cab so
I will take your advice and make swage dies

Cheers
Don

[mklotz]

On the rare occasion where I've needed half round brass wire, I wind some (round) wire tightly on a mandrel, stick it in the lathe and machine away half the wire diameter. Works well in brass and probably steel too but copper might be problematic depending on the grade of copper.

[DonRecardo]

Thanks Marv I shall give it a try

Don

[mklotz]

Given the application, I would think brass, especially one of the harder grades, would be a better choice than copper. It wouldn't dent easily and mar the appearance of the finished loco.

[Frank S]

I really like Marv's suggestion for your application.
Adding a little to it though. since you will be re bending the wire in the opposite direction after machining to a fix it on the model use as large of a cylinder mandrel as you can make the wraps as he stated tight and close together even soft copper would be machinable but you must hone your cutting tool till it is as sharp as you have ever made one just as if you were cutting neoprene to make hydraulic piston seals take very fine cuts at medium high to high RPM. And try not to allow it to heat up as you are machining it as it will expand and become loose on the mandrel
For copper you could even do this on a wood lathe or drill press and use a file like you would dressing any final cut

[owen moore]

I don't how much D wire you need, but for a short quantity, I would probably use the lathe method. If I needed a large amount, I would use the roll form method. This is is much more efficient than doing a wire draw, unless you wanted to make miles of it.

[ncollar]

when I worked for a living we would use a grade of wire to form staples to hold books together and if we put too much pressure on the pusher bearings it would make the wire flat like a desk stapler uses. I would think you could adapt that theory and with a sleeve over a bearing with a groove cut in it to the depth and width of what you want the round to be, then put pressure with the second bearing pressing the wire to make a flat or a D shaped wire. All you would need to do is pull the wire between the two surfaces. My 2 cents out of the box

[Metalmuncher]

You could also mill the desired shape, so long as the width of the flat side of the D is less than the diameter of the wire. I'm talking relatively short pieces here, as the length of the drill bit matching the wire diameter will limit how deep you can bore into the holding material. *

Drill a hole lengthwise (like a tunnel) through some sacrificial material (I like to use UHMW Polyethylene, because it is cheap and mills very easily, but you could probably use any easily milled material) and put the wire in, leaving some stick out on each end. Bend the ends over to hold the wire in place. For example, to do 12 AWG copper, a piece of material 1/2 or 1 inch thick. You would stand it up so the narrow dimension is clamped in the vise. Now, chuck the piece up in a mill vise and mill the surface of the narrow edge of the material parallel to the wire, down until you get deep enough to contact the wire, and flatten it on one side. As long as you don't go too deep, the wire should remain held in the channel you drilled. Once you get it flat on that side, unbend the ends and pull the wire out.

* If the hole you drilled is snug enough, but allows the wire to slip through it, you "might" be able to pull some of the wire through, mill a length of it, pull it through more to expose the un-milled wire, and repeat. If this works, you could theoretically do any length of wire with the block you drilled. But I have not tried doing this.

I used this technique when I needed to mill a flat for a setscrew on the main shaft of an RC electric helicopter. The main shaft is steel rod 3mm in diameter. I was able to mill across it as it lay inside a piece of UHMW, and get a nice tiny flat for the setscrew, without bending the shaft.