Update on Tapered Reamer and Tenon Cutter

My last two posts were about making the tapered reamer and the tapered tenon cutter.  The result was satisfactory, but the tapered tenons still wiggled a little bit in the tapered mortises.  I made another reamer and another tenon cutter and this time the tenon is perfectly snug in the mortise.

I turned a new reamer on the bungee lathe, this time using red alder.  The first one was from a 1 3/4" square blank, which seemed too bulky to me.  This one started out a tad over 1 3/8" square.

Turned very carefully to get a straight taper

I went very carefully to get the conical section as straight as I could, but then I got to thinking about the necessity of having it perfectly conical.  My thought now is that this piece merely holds and supports the blade.  It is the blade that needs to have perfectly straight edges.  The wood doesn't do the cutting and if it doesn't match the blade perfectly, it doesn't really matter to the cut (as long as it's not horribly off).

The next thing I did to make this reamer better than the first was to be more careful about the relief cut where shavings can go in front of the blade.

On the first one I made, I chiseled willy-nilly.
On this one, I drew a layout line and chiseled carefully to it.

I got a much more consistent trench cut on this one, thanks to better layout.

For this new tapered reamer, I also made a new blade, this time without saw teeth and it results in a far smoother cut.  Check out these two pics:

The original reamer blade with saw teeth left deep gouges around the hole

This is the same hole as above.  The new reamer removed the gauges left by the
first reamer and left a very nice surface (the lines you see are annular rings)

For this blade, I honed the edges at 90°.  I think I read (either from Elia Bizzarri or Curtis Buchanan) that others sharpen the edge at 70°.

I also wanted to make another tapered tenon cutter, this time being a bit more careful about layout and cutting.  My blank was about 2" thick, 3" wide and 8" long and I carefully squared one face with one side, then made the other face and side parallel to the first ones.  I laid out a center line along the length and along the width and followed those lines to the opposite face.

Added concentric circles to help me judge whether or not I ream straight

I made the layout lines full length and width for reasons that I hope will become clear at the end of this post.

After boring a 3/4" hole from both sides, I used the reamer to taper the hole.  I checked with a square often to see if I was tapering straight and made any adjustments to fix any straying.  If I was leaning a little left, I leaned the reamer a little more to the right to fix it.

Here's the top (larger diameter side), fairly well centered

For whatever reason, the small end came out a little off center

The small end of the tapered hole was only reamed slightly, as I wanted it to stay close to 3/4" diameter.  But what little I did ream it removed more material to the upper right in the pic above and less by the pencil point.  Well, close enough for amateur work!

I then laid out the 15° angle on top and bottom, the line emanating from the point where the circle meets the vertical center line.

Top surface: note the 3/16" relief for shavings ejection

Bottom surface

After sawing out the waste and carefully paring to the lines, I got a nice flat bed for the iron to rest on (and be clamped to).

The waste removed and a parallel surface marked

To aid in clamping the iron to the bed, I drew lines parallel to the bed, then sawed away the waste and planed to the lines to create a surface nicely opposed to the bed.

Again, I'm using a spokeshave iron for the cutter, clamped in place with an "F" clamp.

The setup ready for use

A test cut came out great - the tenon fit a reamed mortise tightly at both top and bottom.

Tight fit at top ...

... and perfect at the bottom (excess was planed smooth to show the fit)

The last thing I did was to add a curved point to the top of the reamer.  I his videos, Curtis Buchanan uses the pointed top of his reamer to line up the cut with sight lines on a chair seat.  That way, he knows the reamed hole is in perfect alignment.

Made a nice tapering point at the top of the reamer

Here's the thing about these tools.  It's not easy to taper a hole without leaning left, right, front or back.  And it's also not easy to taper a tenon without leaning.  It takes constant checking with squares to make sure your tapers have the center line you desire.

To help with the tenons, I've thought about making some kind of block that would clamp to the tenon cutter.  There would be a hole in the block just big enough for the piece being tapered to fit through.  The hole in the block would be centered using vertical and horizontal layout lines.  I could clamp this block to the tenon cutter, matching up the block's layout lines with the layout lines on the tenon cutter.  That way, I would know that the center of the block's hole is in perfect alignment with the center of the tenon cutter's hole.  And if the block's hole is just a tad larger than the stock being tapered, the stock couldn't wiggle much as the taper is being cut, resulting in a straight taper.  It's just an idea - but one I'll be checking out soon.  Maybe after some practice with the tenon cutter I won't need these training wheels, but they could help.