Black Frog Posted May 17, 2013 Share Posted May 17, 2013 I'm laying out a "dial-a-hole" bolster plate (thanks Brian Brazeal) for my anvil. I'd like to have one of these for sqare holes as well. I'm planning on drilling the holes for the squares, and then drifting them to final shape/size. My material is 1/2" thick, how small of a square hole can I drift through that? Can I drift a 1/8" square through there? I plan on drilling a hole slightly undersized to 1/8" diameter so that I might get a nice square shape when drifting, but wondering if I would be able to do it? I've never tried drifting a square hole that small through that thick of material- thought I'd better ask first! Quote Link to comment Share on other sites More sharing options...
Frosty Posted May 17, 2013 Share Posted May 17, 2013 It may take a couple tries to get the right technique but it's doable. I've drifted a couple pretty small sq holes in 5/15" and a little thicker for nail headers. Just get the plate really hot first and be ready for the drift sticking. I think I'd use a concrete nail, ground for the drift so I could get hold of the head with my speed bar if it sticks. Frosty The Lucky. Quote Link to comment Share on other sites More sharing options...
Rich Hale Posted May 17, 2013 Share Posted May 17, 2013 A couple of small drifts in progressively larger size may help. First one to just square the hole a bit,,then one to enlarge a bit more etc...and if you make the working part of the drift fat in the middle so it moves a little metal then drops out other side it may not stick so bad. There is info on this site somewhere about punch lube...you will need the good stuff. And of course there are always needle files! Had another thought just after posting this: For these small holes you likely will not need all the support of the thick plate. You could back drill a larger diameter hold and leave however much base metal to fit your needs,,then just drift the top part of the hole to size. Quote Link to comment Share on other sites More sharing options...
Black Frog Posted May 17, 2013 Author Share Posted May 17, 2013 Had another thought just after posting this: For these small holes you likely will not need all the support of the thick plate. You could back drill a larger diameter hold and leave however much base metal to fit your needs,,then just drift the top part of the hole to size. Fantastic idea (as I slap my forehead)! Thanks! Quote Link to comment Share on other sites More sharing options...
SmoothBore Posted May 17, 2013 Share Posted May 17, 2013 That is a very good idea, ... that greatly simplifies that particular job. Before making the square drift punch, ... Google up a picture of a "Wobble Broach", ... and take note of the concave shape of the end of the "punch". Rather than displacing the "corner" metal, a Wobble Broach shaves it out, ... pushing the "chips" ahead of the broach. This is the way the hex shaped hole is formed, in "Allen Head", or "Socket Head" Bolts. Quote Link to comment Share on other sites More sharing options...
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