Raw Tenon Cutter Instructions

STEPS FOR FINISHING YOUR TENON CUTTER

(Steps necessary for a working tool are in bold, the others are for aesthetics.)

1. Note blade location and orientation (bevel-down) and then remove it. Sand the handles of the tool. This can be done freehand, or on a lathe (just watch your knuckles). My sequence is 80 grit to 150 to 220. Then sand all four sides of the tool freehand or on a belt sander. I use 180 grit and then finish with 220 by hand.

2. Chamfer the four lengthwise edges of the tool with a small, sharp block plane to even widths. Pay attention to grain direction to get a smooth surface. This can be done while the tenon cutter is still on the lathe, or resting in a v-shaped holder.

3. With the tool clamped in a vise, use a sharp 1” chisel to cut chamfers along the four edges of the two short surfaces opposite the blade bed to match the chamfers that were cut in step 2. Then, cut a thin sliver from each of the first two surfaces to remove bandsaw

4. Any tearout or tool marks can be gently sanded from the through-hole and countersink area.

5. Saw off end nubs and with the tool clamped vertically in a vise, chisel or drawknife the handle ends smooth. Your tool can also be labeled with letter or number punches at this time.

6. Brush the tool with two to three coats of shellac. If you sharpen and set the blade first (see subsequent steps), you can cut a tenon on a scrap piece of wood, keep it in the hole, remove blade, and use this as a handle while finishing the tool. This also helps keep shellac out of the cutting hole. Let cure for 24 hours and then re-sand with 320 grit. Wax and buff.

7. Prep the blade. I like to grind off the small nub at the back of the blade. With a buffing wheel, I also smooth the edges, remove the blade label and any tarnish, and finally slightly round the top, non-cutting, edges of the blade.  Be careful not to round over the cutting edge.

8. Hone the blade. It has been hollow-ground, so honing should be pretty straightforward with your preferred method. Mine is a few circular bevel-only passes on a 1200 grit water stone until I can see the whole front edge has been hit and then several passes on a 6000 grit stone, working both the bevel and flat back (top) of blade to remove the burr.

9. Set the blade and test for proper cutting. See separate Tenon Cutter Blade-Setting Instructions

TENON CUTTER BLADE-SETTING INSTRUCTIONS

1.  Turn or shave a testing stick. Dry oak works best. Turn your stick to <⅛” greater diameter than the entry hole of your tenon cutter. So, 15/16″ for leg cutters, ¾” for arm stump cutters, and 11/16″ for spindle cutters. Taper the end slightly to facilitate entry (or even turn a 6° taper to help pre-set your blade on leg and arm stump cutters).

2.  Loosely install the blade with the turned tenon inserted tightly in the tool if you did this in step 1. (If you don’t have a turned tenon, another tenon cutter can do this, or you can skip this part). Adjust the blade so that it seems it will just start to cut along the length of the tenon. In general, you want the blade located near the center of the blade-bed (again, bevel-down) and the cutting edge to just be proud of, and parallel to, the end of the blade-bed as seen by looking into the hole from the wide end. Tighten the screw lightly.

Spindle Cutters

    Set blade parallel and just protruding into hole as noted in step 2. Rotate test stick with even pressure, pushing towards the small end of the hole.  To increase the cut depth, put a screwdriver against the back of the blade and lightly tap the screwdriver with a hammer (putting the screwdriver directly behind the screw will drive the blade straight, putting it off center will rotate the blade). If you go too far, loosen the screw, pull the blade back and try again.  

    If the blade leaves a ragged burr on the stick, the stick is too big in diameter: turn or shave it smaller. If the blade doesn’t cut, look for burnish marks on the stick. If it is burnishing at the exit hole, either slide the blade slightly to the left (toward exit hole) to align blade better with the bed, or rotate the blade slightly to the left. If it is burnishing at the entry hole, rotate the blade slightly to the right. Rotating the blade may be enough to get the tool cutting, or you may also need to advance the blade.
    
    When the cutter is cutting sufficiently, turn a tenon until it is flush with the exit hole. Remove and check the diameter of the tenon. This is best done with a test hole drilled in the same wood as your chair seat by the same bit you will use to drill your seat (make a series of holes, since they will wallow bigger as you test). You want a tight fit, but not so tight that you can’t twist the tenon at least half way into the mortise by hand.  

    If the tenon is way too big, it will stick in the exit hole of the cutter.  To fix this, either rotate the blade to the left or tap the whole blade evenly forward slightly (most likely the latter). If the tenon is too small, try tapping the blade slightly to the right (towards entry hole). However, it may be necessary to back off the blade and start over. Also, check to make sure the cutter is forming a non-tapered tenon by measuring the diameter of the tenon with calipers in two nearby spots to see if it’s the same measurement. If not, adjust blade until it is. Give blade screw a final tightening with tenon in place to prevent any shifting. The screw can take a solid tightening, but excessive torque can pull the screw insert from the body. If you’re in a humid environment, a light coat of wax on the blade will help prevent rust.

Leg and arm-stump cutters (much easier than spindle cutters)

Rotate test stick in tool with even pressure towards exit hole until it cuts along the whole length of the blade. Check that the cutting action is smooth and even and not too aggressive. Make tiny adjustments to the blade position by clamping the tool in a vise and tapping a screwdriver gently into the back of the blade with the testing stick in place. Tapping either back corner of the blade will rotate the blade in that direction. Tapping in the middle should advance the blade evenly. The finer the cut, the less the tool will tear. Once it is cutting well, check the taper of the tenon with a 6° bevel template or the blade of your reamer. Rotate the blade blade as needed to produce the proper taper, then give the screw a final tightening with the tenon in place to prevent shifting. The screw can take a solid tightening, but excessive torque can pull the screw insert from the body. If you’re in a humid environment, a light coat of wax on the blade will help prevent rust.

Written by Seth Elliott ~Toolmaker

Purchase these tools on the tenon cutters page.

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WOODTURNING FOR CHAIRMAKERS with ELIA BIZZARRI

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