Author Topic: Fixing Drill Bit Misalignment in the DBS-22 Drill Bit Holder  (Read 143 times)

Offline RickKrung

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While I was working on grinding secondary facets on drill points recently (https://www.tormek.com/forum/index.php?topic=3601.0), I ran into a problem getting the large diameter drill bits (3/4") to align properly in the Drill Bit Holder. I had held somewhat similar drills (1/2", 19/32" and 5/8" in the holder and successfully sharpened them without misalignment issues.  I wasn't sure at first what was happening, but on looking closer, it was possible to see the misalignment.



Placing the misaligned drill on the jig platform and holding it near the grindstone made it more obvious that uneven grinding would occur on the facets.





Although the drill bit holder has several fingers on each side of the drill that should hold the bits evenly and straight, that was not happening for this drill bit.  The best I could figure out is that there weren't enough contact points of the flutes with the fingers. 



I could not get it aligned such that it would remain in place during grinding, so I devised a method of holding it, essentially a long, thin-walled spring collet.  It consisted of a length of stainless steel tubing, 3/4" ID and 7/8" OD, which I put in a horizontal metal cutting bandsaw and cut slits along its length.  One slit went all the way through one side of the tubing.  Several more went most of the way through, but not all the way. 







This allowed the tubing to flex enough to securely hold the drill in place by gripping the drill bit flutes all the way around each flute over the full length at all four locations at which the drill bit holder made contact.  Viewed on end. 



I was fortunate to have the appropriate size tubing on hand to make the slit spring collet.  Most of you will likely not have the right material.  I have not tried it, but I think it is likely that PVC tubing could be used instead.  It probably would require drilling out some pipe that isn't the exact right size and then cutting the slits.  This could work for several drill sizes close to the ID of the pipe.  The OD doesn't have to be exact, as the pipe could expand a fair bit, with a wide gap at the full depth slit, as long as that gap didn't fall right on one of the four clamping surfaces of the holder. 

It would be nice to understand better why this misalignment occurred and be able to correct it without resorting to additional gadgets or tooling.  In lieu of that, I found a fix that worked for my situation.

Rick
« Last Edit: May 09, 2018, 04:11:22 pm by RickKrung »
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Offline Grizz

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Re: Fixing Drill Bit Misalignment in the DBS-22 Drill Bit Holder
« Reply #1 on: May 09, 2018, 04:16:05 pm »
nice simple fix for a complicated problem ! good job !

Offline Ken S

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Re: Fixing Drill Bit Misalignment in the DBS-22 Drill Bit Holder
« Reply #2 on: May 09, 2018, 05:19:31 pm »
Well done, Rick.
Ken