|
Looking
to make some staked furniture...with legs
that involve tapered tenons and tapered mortises.
My
first attempt will be a sawbench...
The
design is similar to the sawbench shown below but this
prototype will be made from treated pine in the lumber pile.
 The designs are based on the readings and plans from Chapter 4 of The Anarchist's Design Book by Christopher Schwarz.
|
|
| Skill
building for this project involved learning to drill pilot holes
at a 15° angle. Having trying a number of different methods I settled on using a hand held power drill with a Wood Owl bit using a shop built jig...as an angle guide. |
 |
| 15° accuracy will be achieved by
using this shop built guide. |
 |
|
Then a hand bored tapered hole
will be made using the pilot hole as a guide.
The taper tool will be the Veritas
Pro Taper Reamer.
|
 |
|
Manual
for the reamer.
|
|
| The reamer is
set at 12.8° and is the complement of the Veritas Tapered Tenon Cutters |
 |
| Manual for the tenon cutters. | |
| Design, Materials, and Milling | |
| For this prototype, I will use
the resultant angle of 15° and
dimensions similar to those given by
Schwarz in Ch. 4 My top slab will be 2.65 inches thick x 7 1/16 inches wide by 19 3/16 inches long. The legs will be 1.25 inch square instead of 1.75 but this is the size stock I have available. |
 |
 Layout of the top slab |
|
| Due to pandemic lock down, I do
not have access to many wood choices right now. The woods that I
will look to in the future will include white oak, poplar, ash. I had a 2 x 8 treated board that had dried in the rafters...jointed it and planed it and came up with slabs that were ~1 3/8 thick...glued up two pieces to make milled top blank of ~10/4 stock. |
 |
| Legs will be
approximately 1.25 x 1.25 stock...I made extras for CTDs. Slab and leg milled stock shown. |
 |
|
Layout on Underside of Top Drilling and Tapering of Mortises |
|
After marking out
the locations of the mortises, the sight lines were marked off
(64°). The Starett protractor head on the 24 inch rule was perfect for this task. |
 |
The resultant angle for all four legs will be 15° along the sightlines. Jig is lined up and secured at bench...sacrificial board to help with spelching...hole aligned with open vise. |
 |
| Alignment at the front of the
jig...used a longer hold down...issue with surface mating... |
 |
| Second hole...bit slightly
screwed into layout hole... |
 |
| Then the jig is lowered to
surface and secured... |
 |
| First two holes...alignment is
decent... |
 |
| Then
there is a total failure of the jig...on hole three I believe
that I tilted the bit, reamed one edge, and changed the jig
angle. I did not realize it at the time...I moved on to hole four...halfway through the slab I saw that the front hold down had slipped and the jig had moved. I tried to recover and only made things worse...both in the work piece and in the angle of the jig. A major problem with the bit in the jig concept is that you can not check yourself periodically and make adjustments. You have to depend on the jig to guide you and if there is a small problem there is no way to set things right. So, I will toss the jig and ...I will abandon the shop built angle guide idea, and I will bore the 15° pilot holes using the angle gauge to guide me. Also, the slab is a loss...I cut off the two ends and will use the short slab as a CTD. |
|
|
Crash
Test Dummy Build CTD Mini |
|
| Post pandemic
shutdown...James came to visit...we worked on a CTD mini bench
using the wasted slab from above... |
Layout was reduced onto the CTD mini slab. |
| Drilling...we were able to use
two angle gauges and two sets of eyes to bore the 15° holes... first the holes drilled with owl bit in Festool driver... |
 |
| The conical hole was shaped by
the Veritas reamer in a hand brace. |
 |
| We are newbies on the lathe...set
it up to learn to create a slightly fat conical tenon to prep it
to be shaped to match our conical mortise. |
 |
| Used Woodpecker calipers to gauge
while lathe is turning... |
 |
| Finished pre-conical
leg...end will be trimmed off. |
 |
| Roughed out pre-conical end... |
 |
| The pre-conical end was then
placed into the tenon cutter to shape a 1/2 inch tenon. |
 |
| Finished CTD octagonal
leg...shaped conical tenon is a perfect fit in the conical
mortise. |
 |
| Dry fit...so tight you had to
pound on the leg to get it out... |
 |
| Determined the layout of the legs
according to grain...marked out kerfs, cut kerfs in legs with
handsaw...image is dry fit. |
 |
| Made a jig to cut 4° oak wedges
on bandsaw. |
 |
| Dry fit of wedges... |  |
| Glue up |  |
| Tenon ends and wedges flush
cut... |
 |
| Octagonal legs were
marked...board = 1.25 inches... |
 |
| Hand sawn with Bad Axe tenon
saw... |
 |
| Chamfered all eight sides... |
 |
| Put a large chamfer on the slab top at 45° at router table |  |
| CTD Mini will be used on the
screen porch as a foot rest to tie my boots... |
 |
|
Pair of
Sawbenches Build |
|
| Materials: yellow
pine...sought out dry boards at orange BORG...grabbed two 2 x 8
x 10s and one 2 x 10 x 10. The wood had been there awhile...pandemic pricing had dropped... |
 |
| Wood was marginal but I was able to mill everything I needed. |  |
| Glued up the two top slabs... |
 |
| Clamped both slabs at once... |  |
| Turned Leg Sequence Conical Tenon |
|
| Ready to make eight legs for the
pair of sawbenches...need to get a template and sequence going
to simplify and speed up process. Worked to create a template to guide the turning of the conical leg tenons. |
 |
| CTD that we liked...converted to layout stick. |  |
| I had to learn some new skills to create all of these faces in Sketchup. |  |
| Layout Stick |
 |
| A template and
layout CTD was created...PDF. |
 |
| Sequence for easiest lathe work...PDF |  |
| Main layout marked in
pencil...Step 1 and Step 3 turning locations are marked in red. |
 |
| Step 1 turned to ~1.25
inches...just enough to round the stock. |
 |
| Step 3 turned the tip to 3/4 inch
diameter. |
 |
|
Steps 2, 4, 5, and 6 create
the stop lip and then tapered 1 1/16 to the 3/4 tip.
Step 7 is the v groove. Step 8 puts the cove. |
 |
| Sawed off the waste. |
 |
| Used the 5/8 inch tapered tenon
cutter. See tenon cutter holder jig. |
 |
| Routed the legs at 45°
to form octagonal. |
 |
| Made eight...by the time the production run was over the time it took to turn a bank into the tapered octagonal leg was around 15 minutes. |  |
Leg Tenon Insertion and Securing |
|
| We were trying to improve upon
our conical mortise layout, drilling the conical mortise, in
particular the angle of the tenon...15° Due to the strong grain pulls in the top blank...any early errors had dramatic subsequent on the show side...and the angles... the image is after the dry fit of mortise and tenons. One can see the dramatic grain variance in the yellow pine blanks. |
 |
| We assessed our use of the bird
cage awl (pictured here) and decided its use caused
increase drill bit wander right from the very start due to the
square grind on the point. We opted to change to a standard awl and made the angled entry point during the layout. The rest of the drilling cycle was done like in the sequence above, here. |
 |
| We also tried to make a 3/8???
layout bar the standard for for the distance between the "stop"
ring on the leg and the base of slab. |
 |
| We made some more oak
wedges...still not really happy with this process. Earlier picture... |
|
| Set and glued the conical tendons...pounded the wedges. |  |
| Most wedges of this batch set
well...one wedge broke (see clapped corner). Most of the
elliptical holes were filled satisfactorily but one was bad off. |
 |
| Then dry mortise/tenon/wedge
extensions were cut off ...the mortise on the right is the one
that was way off. The sawdust, from pine and oak cutoffs, was mixed with yellow glue and sanded flush. |
 |
| Here are the 8 wedged
tenons...flushed and sanded... |
 |
| Moved the bench to
determine the leg most wobbly...placed the shim under the
leg...in image, right lower corner. |
 |
|
To achieve the bench
height desired I had to cut off approximately 3+ inches...made
a stack with 1-2-3 blocks to create the three inches and then
used the rule to enable easy marking on the slanted octagonal
legs.
|
 |
| Marking the legs for cut off. |
 |
| After cutting off the four
legs...the bottoms were planed or sanded as needed. |
 |
| During process of marking the
legs of the second bench James had a good idea to elevate the
bench by supporting it in a level position and then mark the
four legs...this eliminated the need to shim under the legs. |
 |
| Rounded over with edge cornering tool. |  |
| Finished pair. |  |