Wednesday, November 30, 2016

Experiment With Angled Dovetails: Poplar Step Stool

I have a step stool that I made several years ago in my power tool days, based on one I read about (if memory serves) on this blog by a very prolific and inventive fellow.
The old step stool

It's been great and I use it all the time.  The legs angle out from the top by about 10°.  The hand holes make it easy to pick up.  But it's just screwed together.  We can't have that, now can we?

I've been interested in trying out angled dovetails.  I want to make a step stool from three boards - a top and two legs - with the legs angled out and joined to the top with dovetails.
Three boards glued up from scraps from my recent chair project

There is a great video on YouTube by "Half-Inch Shy" explaining how to do this type of work.  But my situation is different from the ones he covers.

Turns out my situation is easy.  Once you plane a bevel on the ends of your boards, the layout and cutting of the DTs are practically the same as 90° DTs.  The angle I'm using is about 12°.
Marked the 12° bevel
Pencil lines to help monitor progress
Half way there
Thank goodness for knife lines to guide the way!
Eventually get a good crisp bevel
I marked out 6 tails, starting from a pin that was marked 1/8" either side of the center line.
Penciled in center pin, then stepped off the tails using dividers
Tails marked
This was not as easy as I first thought.  With the beveled end, I didn't want to use my standard DT marker because of it's short registration surface.  So I used a bevel gauge and even here I had to be very careful that the gauge's stock had full contact on the end of the board.
Front of gauge's stock not registering properly on the end
Cutting the tails was straight forward as long as you remember that the base of the cut had to be at the same angle as the end of the board.
Using a backer board to help make straight cuts by lengthening the cut line
When chiseling out the waste, you have to chisel at an angle.  I used my bevel gauge again at 12° to aid with the angle.
Bevel gauge helps guide the chisel angle for the baselines
To transfer the tail outlines to the pin (leg) boards, I had to rig up something to account for the splay angle.
Marking the pin board from the tail board
Cutting out the waste on the pin boards was straight forward - used a coping saw for the bulk and chiseled to the lines.

Gotta stop and talk about a small epiphany I had regarding knifing lines.  I don't knife a single long baseline when dovetailing - I like to knife each waste piece separately.  That means I have to stop the knife before it gets into the keeper wood.  I can't tell you how many times the knife suddenly moves and it's too late to stop it.  But I discovered a technique using my middle finger as leverage to help pull the knife in a more controlled manner.
Knifing the baseline of one waste area
Using middle finger to stabilize the knife hand and enable a more controlled knife cut
There's a subtle difference in the two pictures above, but it's an important one.  Try to ignore my left hand that is holding down the combination square.  By placing the middle finger of my knife-wielding hand on the board I had better control when cutting up to, but not over, the waste line.  I could actually pull the knife using a bit of leverage that the finger enables.  Great stuff!!

OK, back to the project.  After lots of trimming and test fitting I got a decent fit.
First end dry-fitted
Both ends dry-fitted - starting to look like something
Time for some shaping.  I wanted to cut out a half-elliptical shape on each leg to create two feet on each side.  After experimenting with some shapes, I used a French curve to create a template.
Cutting a template
Marking the leg
Then cut out the shape with coping saw and smoothed with rasps, files and scraper.  I also angled the sides of each leg so they were narrower at the top.

For the top, I had marked two elongated holes.  The ends were drilled using a 1.5" Forstner bit in a powered drill (OK, I admit to using a power tool here) and the waste between them was removed with a coping saw, then smoothed with rasps and files.
Starting the hand holes
The above picture also shows the arc that will be shaped on the sides.  No action shots, but a saw, chisel, spokeshave, plane and scraper were used to make and smooth the curves.

I made some 12° cauls to help with the glue-up.  Coarse sandpaper adhered to the underside of these cauls kept them from crawling up the angled legs when pressure was applied.  I also fitted a couple spacers so that the feet wouldn't be forced towards each other during clamping.
Glue up - see the spacers resting between the feet?
Planing the joints after the glue dried was a little challenging due to the splay angle.  I had to be creative in figuring out how to support the piece.
Position for planing the leg half of the joint
Using the center slot in my bench for planing the top half of the joints
The cleaned up joint - not perfect, but I'm happy with it
I've applied two coats of shellac and after a final sanding it will be ready to be put to use.  And here's your glamour shot.
Thar' she blows!!
A relatively quick and useful project using scrap wood.  The angled DTs were fairly easy - no real tricks here.  I'm going to have to try some of the other types of angled DTs soon.  Maybe on some Christmas projects coming VERY soon.