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I need advice on forming a 0.47” OD with 1/16” stainless wire

DanBrub

Aluminum
Joined
Feb 14, 2019
Location
Tennessee
Have a project that requires a closed loop of 1/16” 304 stainless wire that has a finished OD of 0.47 on the end of a straight length of the wire that is 10” long. The end of the wire loop needs to be within .020 of touching the straight section. I have attempted a mandrel that is .305” and tightly wrapped about 1-3/4” turns around it which after spring back is pretty close to the desired measurement but requires cutting the tag end and trying to hand bend the loop back into into the same plane while keeping the end within the .020” gap. I know wire bending machines are probably the solution but the quantity of these needed don’t warrant the investment in a wire machine.

Any suggestions on how to do this efficiently?

Thx
Dan
 

jscpm

Stainless
Joined
May 4, 2010
Location
Cambridge, MA
The loop you are describing is called an "eye" in the bending trade. The easiest, simplest method is to use an eye bender. An eye bender is metal plate with two cylindrical posts in it, the diameter of the larger of which determines the size of the eye.

This video shows the basic idea: Making Hardware From Wire - YouTube

Note that this guy has pretty bad eye bending technique because he is over bending and cutting off, which you do not need to do. To see better technique, watch this guy use a hossfeld bender to make a proper eye: Hossfeld Bender: Eye Bolt Setup & Other Basics - YouTube

Notice how he reverses the bend to make the junction of the eye.

If you want to one off it, you can do a progressive bend. This requires a hammer, an anvil and a certain amount of skill, so if you have never done it, you would need to practice before your circles would be good. Here is a video of a blacksmith demonstrating his progressive arc skills:

Backsmithing - Back To The Basics - B1E3 - Bending Eyes - YouTube
 

DanBrub

Aluminum
Joined
Feb 14, 2019
Location
Tennessee
Thank you for the reply jscpm but the item I'm trying to form is a bit different than the "eye" in the videos. Here is an Image of the loop I'm talking about.
Wire Loop.jpg

My concern using the anvil approach is that even if the hammer was brass the anvil may leave impact marks plus trying to get the end of the eye right up against the straight section would pretty much require using something almost chisel shaped and thus need to be hard enough not to deform so another potential tooling mark on the loop.

Gripping the wire to "pull" it along the circular path is another challenge. If I use a hole and run the wire deep enough into the hole to ensure it doesn't pull out then after the loop has been formed the end of the wire in the hole must be cut so adds another challenge. A slot will allow you to slide the wire loop off along with the end that was trapped in the slot but it too must be trimmed without damaging the loop. The stainless is pretty hard to nip and this also leaves a sharp end so not desirable.
 

4GSR

Diamond
Joined
Jan 25, 2005
Location
Victoria, Texas, USA
Just about any spring vendor can make that loop on a end of a piece of wire.

Talking about one piece or several hundred?

Katy Spring Company in Houston is one vendor I deal with. We have several others in the Houston area that can do this, too.
 

jscpm

Stainless
Joined
May 4, 2010
Location
Cambridge, MA
The shape you show is even easier than a normal eye. You just put the wire in the bending posts and wrap it around. I have shown below an example of a bending post that will do this bend:

loop-bender.jpg

Note that this setup uses a wedge to pinion the end. This allows the bend to be done in one move. However, it can also be done with a round pinion. In that case you just do half the bend, the turn the wire in the post a little bit to finish it.
 

DanBrub

Aluminum
Joined
Feb 14, 2019
Location
Tennessee
I like your drawing. I have tried the round pinion and could never get the end to form but didn’t try it in two steps as you indicate. To make sure I’m understanding your design am I correct in thinking the wedge moves around the bend post forming the wire as it rotates around or is the wedge holding the tip during the bend? The stainless has considerable spring back and I had to “over-rotate” the wire thus when relaxed the end was close to the straight section. Do you think that is because I was not adequately forming the tip into the circular shape.
 








 
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