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Re: Hand Bending Machine
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Posted by Chris Ray on August 08, 1998 at 17:03:35:
In Reply to: Hand Bending Machine posted by Bill Housden on August 08, 1998 at 14:43:32:
The following device is about as simple a thing to make and use for bending operations as you can get. I just made one yesterday as a matter of fact to assist in tweaking and fine tuning some bends on a project I'm now working on. It's a variation on a typical forged bending fork. This unit is designed to be held in a heavy duty machinists vise.
I'll describe a simpler set of bending forks than I just made for working 1/2" squares as follows:
For the base plate drill two holes in a bar 3/4" x 2" by length. Space the holes about 1 1/2" apart off the center punch mark. Drill off two 1/2" diameter holes through the metal.
Next cut two pieces of iron pipe with a 1/2" dia. opening then about 1" high or so then insert 1/2" bolts through each pipe. Secure these upright pins to the base plate with a nut and tighen firmly. It's important for strength and stability that the cuts in the pipes be accurately done so they are perpendicular to the length. Otherwise they will tilt giving you a twisted bend.
If you like, you may also drill off additional 1/2" holes spaced along the base plate. This will allow you to insert radius dies which you may either have or can make with laminated plywood drilled out for bending lightweight strip steel.
For a simple lever type of bending fork use something like solid 1" square bar. Cut a couple of lengths of 5/8" round bar stock and weld one bar near the end of the bar on one side. Back down the bar a bit (maybe 2" or so) and weld the other short bar on the opposite side of the bar. The bars then become the forks.
There you have it. A down and dirty pair of bending forks that can save the day for you. You can vary any of the dimensions to suit whatever material you have on hand that will be sturdy enough to hold up against the weight metal you are bending.
The set I just made up is a little more sophisticated than this but just as easy to make if you have the parts.
I used the same base plate as described above. For one pin located near the end of the plate I used a hardened stripper bolt 3/4" dia. stepped down to a threaded portion that is 5/8". These can be ordered from machinist suppliers. Over the pin I slipped a heavy walled pipe that was turned on a lathe to assure accuracy of the top and bottom faces. A pipe cutter would do pretty much the same if you file the faces flush afterward.
Next I used a pair of heavy duty ball bearings that I stacked giving me more than 1" on the face of the wheels. I bolted these with a hardened cap bolt (allen type) through a second hole located about three inches from the first. My clearance between the two pins is about 1". The capacity hasn't been tested but I think I can bend flats at least 1/2" x 1 without a sweat.
The hand held fork is the same as described above except that I forged a comfortable taper along the length for more leverage and better balance.
Why did I use ball bearing wheels for this? Because it makes it silky smooth to ease the bars to be bent as it's pulled or pushed into position. Not something that's necessary by any means but it's just nice to reduce the annoying friction sometimes when you use this sort of thing a lot.