Behold: The Unbender!

As I wrote at the beginning of my making kitchen knives project (oh my, is it over a year already?), the steel bars often need straightening before a knife can be made out of them. The method I used then was not particularly time-consuming, but it was very annoying, with the screws constantly falling off to the ground and me cursing all the time. So I have decided to build a jig to help with the job. And here it is.

© Charly, all rights reserved. Click for full size.

This simple thingie took me a ridiculous amount of time to make. Like, three or four times more than it probably should. It might even have cost me more time to build it than I will ever save by using it, depending on how many knives I will make in the future.

The principle is simple, there are three rollers made from old piping and some ball bearings. Two are fixed to the base plate and one is on a plate sliding on two columns opposite them and center between them. A screw in the center can push the upper roller down between the two stationary ones and thus it can bend steel.

© Charly, all rights reserved. Click for full size.

The use is easy. Put the end of a flat bar between the rollers with the concave side down, tighten the central screw a bit and pull the steel back and forth end-to-end through the rollers (but careful not to pull it out completely, because that would mean starting over). Then check for straightness, eventually tighten the screw a fraction, pull, check again, rinse and repeat until the bar is straight.

It works actually very well. I have straightened all my bar stock in minutes and to a better degree than I was able to achieve previously. But still…

Well, hopefully, the finishing works on the forge will go a bit faster, because without the forge I can’t do squat.


  1. says

    Wow, that’s impressive!
    I use two pieces of copper wire and my blacksmith’s vise. One piece is in a ‘U’ shape and the other is straight, so I can position the bend and bend factor by adjusting the width of the ‘U’. Even the width of a 12-ga copper wire is enough to snap some blades.

  2. says

    Many years ago I needed a strip bender (sort of the opposite of what you need) so I built a similar machine where the two lower rollers were fitted with spur gears driven off a central shaft that turned them both. A big crank handle made feeding the strip easy.

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