I'm thinking of making my own hollowing rig and tools, what is the radius of the medium bend and the larger bend? I'm thinking along the lines of the trent bosch and john jordan tools and starting out with 1/2 bar.
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I'm thinking of making my own hollowing rig and tools, what is the radius of the medium bend and the larger bend? I'm thinking along the lines of the trent bosch and john jordan tools and starting out with 1/2 bar.
I have made several; I did not measure the radius but estimate it to be ~1-1/2" for the one John Jordan tool that I have (1/2" bar). If you make HFs with small openings, you will end up with multiple curves and bar sizes. These tools are easy to make, no need to over-analyze it; just make a couple. After you use them, you will know if you need one with different bar size or curves.
Start with a straight tool and one with the tip at 45 degrees. Add goosenecks as you see the need.
Make the rig to accept 3/4" bar and make a step down adapter to 1/2".
I bought 3/4" aluminum round bar stock, cut 4" lengths and drilled them 2" deep - some 1/2" diameter some 3/8" diameter. Then drilled and tapped two holes for set screws and 'permanently' mounted one on each of my smaller boring bars. Now all bars fit whether I'm using a long straight handle, cranked handle (I have Don Pencil's Scorpion armbrace), or one of my home-brew rigs. I don't have to waste time looking for an adapter when I change bars, which you should do several times in the process of hollowing.
I have not fabricated gooseneck style bars. I understand that if you can bend the steel, they are not difficult to make, but i found that except for a few special tools, I like the commercial ones better.