Friday, August 23, 2013

Knurling/parting tool holder

My Knuth DBF400 came with a pretty basic tool post that has no provision for setting the tool on center.  In addition, it doesn't accommodate tools taller than 5/8" so this means I'm on my own for all my larger tools.  One of such tools is a knurling tool from an Atlas lathe I found at a garage sale, so I designed and built a holder for it.
Inverting the colors makes the blueprint look 100% more authentic
It started with a piece of 1x2" steel 2.5" long.  Since this is hot rolled steel, the dimensional tolerance is pretty low (or is it high) and was less than 1" and more than 2" on the respective sides, giving me less room to work with.  Anyhow, the piece was milled to the shape.
For some sides, the milling quill wouldn't go down far enough, so I had to do some dual-vise action.

Milling the side that goes in the tool post.
Milling the part where the tool goes.
....and more milling
Then finally, drilling and tapping the screw holes, using a #10-32 tap with a spring loaded tap centering device.  As much as I advocate #10-32, I think it is too fine of a thread for this application.
All done, but it doesn't stop there....
By turning the it upside down and adding a shim, it also holds the parting tool.
Ignore the excessively long screws
After a bit of use, my wreckless tendency of over tightening stuff has caused the tool holder to bend noticeably.  Had I more than 1 inch to work with, it would've been thicker and not bent.
Also, when tightening it in the tool post, it mashed the metal down causing it to deform the rectangular shape.  I forgot that I shouldn't expect much resilience from mild steel, let alone hot rolled.

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