Dremel 258 Series I

Some years ago I was given a non working Dremel Model 258, Series 1. I fixed it (wires loose on commutator) and have been using it ever since. (and I just fixed another 2 loose wires this morning 8 Oct 2002). It came with a few bits and a 1/8" collet (the old hardened steel type). Over the years that single collet has been a stumbling block, and many times I said to myself "when I get a lathe I'll make some more collets".

Well, I got the lathe in 2000 but only made the collets this last weekend (5-6 Oct 2002).

Of course, things like this don't just happen smoothly. I had to manufacture a slitting saw as well! I made the blade from a blunt roller cutter blade, grinding the sharp edge off and then free hand grinding relief on the bench grinder before 'nicking' the teeth in with a 1mm thick cutoff disk in the angle grinder (blade held in vice). The arbor is a simple affair from some 15mm bar I had lying around and a M6 bolt.

The bits I have, being from my dentist, are all 2/32" and 3/32" shank sizes (which I eventually twigged, I'd measured the 3/32 as 93 thou and could not imagine why anyone would use that size, but 3/32 is exactly 93.75 thou so it figures :-) Not having anything but metric drills I had to convert a couple of the bits into D-bits so they could bore their own holes to size. This worked fine for the 2/32, but the 3/32 bit was soft and I had to harden it after a few drill/blunt/sharpen/drill/blunt cycles. I first drilled the holes very carefully with metric bits to the closest size, trying my utmost to ensure axial holes. They're very close, twist drills are not all that good at this!

That's the story, here are the pictures.
PS: I note on the Dremel web page that all their current collets are aluminum. ugh!


Some cutters and the 2 brass collets I made, along with the somewhat battered original steel collet.

Last edited February 20 2013 09:52:52.
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Cutting the slits using a quickly made slitting saw. The blade is a dressmaking roller cutter blade with the sharp edge ground off. Then, after marking roughly with a 'Sharpie', I cut the 'teeth' with a thin cutting disk in a 4.5" angle grinder. The blade is mounted on an arbor in the lathe with the workpiece in the toolpost. I made each collet on the end of a fairly long brass rod and used that to hold it while I did the slitting, before parting off.

Last edited February 20 2013 09:52:54.
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Last modified: February 20 2013 07:52:36.