Expansive Auger Bits, Part 2

Last time I discussed how expansive bits work and showed the sharpening of the Irwin #2.  Today's post will cover the Clark Expansive bit from T&L Co., New York.  BTW, I could find zero information on T&L Co.  My guess is that they were a hardware store or distributer who put their own name on a tool made by a bigger name company.

The markings on the tool

This one was found with only the small cutter

When tightened, there is a good size gap where I'm pointing

This bit (left) compared to the Irwin #2

This Clark expansive bit is made differently from the Irwin.  The clamp (lower left) is a separate piece, and tightens the adjustable arm into the dovetailed "way" when a screw is tightened.  On the Irwin #2, a slot is machined in the body of the bit and the screw has to bend the metal to force the adjustable arm into the dovetailed way.

Notice the difference on these two bits where the adjustable arm dovetails into the main body.  With the Irwin #2, the adjustable arm just fits much better into the dovetailed way.  With the T&L Co. bit, there is some slop, and this leads to a large gap (about 1/32") between the radial cutter of the adjustable arm and the main body.

I sharpened the adjustable arm's radial cutter and spur like I did on the Irwin #2.

Used a dowel wrapped in 220, then 600 grit sandpaper to work on this concave area.
You can see at the cutting edge where a previous owner cut a much more severe angle at that edge.

Used a very fine file and extra fine diamond paddle to dress the front edge of the spur.
Also removed the burr from the outside with VERY light passes of the diamond paddle.

Then I got to the cutters on the main body.  This one differs from the Irwin #2 in that it has a spur on the main body.  In effect, it could be used to cut a 7/8" diameter hole by removing the adjustable arm and boring with the main body of the tool.

Radial cutter (red arrow) and spur (yellow arrow).
The radial cutter was very dull and needed files and diamond paddle to get it sharp.
Note the "escapement" for chips to go after being severed from the wood.

Look at the shape of the spur.  Clearly it has been sharpened too much or very badly.
I went very carefully to sharpen it without losing any more height.
Note how this radial cutter and spur are cantilevered out from the base of the lead screw.

Before I did anything with the dovetailed ways to reduce or eliminate the gap, I tried out the tool on a 2x4.  It cut very nicely and left clean walls on the (approx. 1 5/16") hole.

Red arrow: adjustable arm's spur cutting the circumference.  Radial cutter not yet cutting.
Green arrow: main body spur cutting a 7/8" circumference
Yellow arrow: a thick chip coming through the main body radial cutter escapement

OK, so here's what I'm discovering.  The thick chip in the above photo is coming towards the camera.  It is coming through the main body escapement and doesn't even get near the gap (clearly seen just below the chip in this photo) between the adjustable arm and the main body.  So it doesn't get clogged in that gap.  I bored a couple of holes with this bit and didn't get any clogs.

Smooth walls on both long and short grain

Here's a chip that came off one of the radial cutters - not sure which one

Here's the only chip that got caught and it was inconsequential

While this bit cut nicely, the hole got a little larger at the exit than at the entry.  So, just like with the Irwin #2, the adjustable arm slipped a little.

Just wanted to add a little more about chip clogging.  I noticed a big difference in the position of the main body radial cutter between the Irwin #2 and the T&L Co. bits.  Look at these pics, both of which have the adjustable arms in the same orientation.

Irwin #2 main body radial cutter

T&L Co. main body radial cutter

The Irwin #2 main body radial cutter forces chips into the location where, if there was a gap, they would get caught.  As we saw a few pictures ago, the T&L Co. bit expels chips away from the seam between adjustable arm and main body.

This Irwin #2 radial cutter forces chips down towards the seam between the
adjustable arm and the main body.  There is no gap, so all is safe.

I don't know about you, but I find this fascinating.  I wonder if the manufacturer of the T&L Co. bit knew something that Irwin didn't.