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Bar stool - locking mortise and tendon joint

Started by Larry, January 27, 2021, 10:33:46 PM

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Larry

I'm making a simple little stool to use at my reloading bench.  Thought some might be interested in the construction.

I think this method of putting legs into a bench or seat might date back a few hundred years so it can be done with hand tools.  The quality Windsor chairs are made this way.

First I drill holes in the seat for my legs.  I'm doing it on my wood lathe using the lathe indexing for spacing.  I set my home made boring block to drill at a 11 degree splay angle.  The traditional way is to use a bit brace with an auger bit.  In the picture I'm drilling through the top of the seat.






I've turned the legs on the lathe out of wet green wood.  I've left extra meat on the tendon that goes into the mortise on the seat.  I want to super dry the tendon to less than 5% moisture content but keep the rest of the leg at 20% or more moisture content.

No problem.  I wrap all of the leg with aluminum foil except for the tendon.  Stick the tendon in my sand filled coffee can.  Turn on the hot plate to heat no more than 180 degrees and in 30 hours my tendon is at 4% with no degrade.




I put the legs back on the lathe and turn my tendon to finish size.  Next step is to fit my super dry tendon into the holes in the seat.



As you can see the tendon has a taper, 6 degrees included angle to be exact.  When somebody sits on the stool the joint will get stronger just from compression.

I taper ream the holes in my seat with my taper reamer.



I just made this taper reamer a few days ago.  The osage orange is still a nice yellow.



The donut top center is a gauge to check my fit on the legs.  The wood to the right is another gauge I can use to insure my taper on the leg tendons is accurate.

My seat is almost at EMC cherry.  As it dries the mortise will seize the leg tendons in a death grip. :D 

Next step is to turn the leg stretchers.  I'll turn them out of air dried wood.  They will be small enough I can nuke them in the microwave to less than 4% (I'm not sure if they used microwaves 200 years ago).  I'll fit them into the wet legs (that's why I wrapped the top part of the legs with aluminum foil).
Larry, making useful and beautiful things out of the most environmental friendly material on the planet.

We need to insure our customers understand the importance of our craft.

Walnut Beast


Ed_K

Ed K

21incher

Thanks for sharing your secrets with us. I have to copy your drilling jig.
Hudson HFE-21 on a custom trailer, Deere 4100, Kubota BX 2360, Echo CS590 & CS310, home built wood splitter, home built log arch, a logrite cant hook and a bread machine. And a Kubota Sidekick with a Defective Subaru motor.

Larry

16 degrees outside and windy.  70 degrees in the shop.  Didn't take long to decide I wanted to make stools today!

Pulled some walnut crotches out of stock to make seats.



Got some maple seats cut out and ready to carve.



This is the completed stool that started this thread.  I got input on how I can improve and have made design changes on the stools I'm making now.



Larry, making useful and beautiful things out of the most environmental friendly material on the planet.

We need to insure our customers understand the importance of our craft.

Walnut Beast

Just curious Larry are they kiln dried or just air dried

Larry

I kiln dried the walnut 20 years ago but its at air dry EMC now.  The rest is air dry or even a little wetter, especially the legs.
Larry, making useful and beautiful things out of the most environmental friendly material on the planet.

We need to insure our customers understand the importance of our craft.

kantuckid

TENONS not TENDONS! :D 
I've made a lot of stools. I never use a tapered hole. In a solid top I always use a straight sided hole and a tight fitting, dry tenon which has been sawed with a thin kerf slit to receive a thin wedge of hard wood. I like contrasting wood so mostly use Osage Orange or Walnut for my wedges or Maple in Walnut. I always use glue on tenons and wedges. The wedge kerf needs to be placed in the leg tenon such that the forces don't tend to split the top grain over time. 
Drilling angles I often use a drilled block with my angle as a guide combined with angled drill press setups. I prefer a wedged tenon or a tapered tenon as they start tight and stay tight. 
   
Kan=Kansas;tuck=Kentucky;kid=what I'm not

ESFted

Larry,
Nice job!  Thank you for taking the time to show us your process.
S.U.N.Y. College of Environmental Science and Forestry '65
Stihl MS661CRM, Stihl MS460,  Stihl MSE 220, Solo 64S, Granberg Alaskan MK-IV CSM
Dreams of a Wm LT70 w/all the accessories

samandothers

I appreciate your sharing your approach.  The use of the sand bucket was ingenious.  Thanks to you and others on sharing approaches to facilitate your processes.

Tom King

There is currently more demand, than supply, for such chairmaking reamers, and      tenon      taperer's.   Someone could have a side business making them.  Some chairmakers sell them, but they're usually busy building Windsor chairs, and can't keep them in stock.

Windsor chair stretchers often have wedged tenons into stopped holes, that are bulbed out inside the mortises to allow for the end of the tenon expanding.  Some have a dry bulb, popped into a green leg mortise.  They use the same sand method, or some variation such as a light bulb in a box, for drying the top leg tenons, while leaving the rest of the leg green.

Larry

I've become fascinated with making stools and have researched some of the better makers.

Wharton Esherick (rip) seems to be the grand daddy.  Hurry and ya can buy three of his stools for $38,000 plus shipping!
Wharton Esherick stools

I did wedge the legs on my first stool but not the stretchers.


The stool I'm working on now is getting a carved top.


I plan to wedge the stretchers just like Wharton.

The carving is something new for me.  I made a vacuum clamp to hold the seat.  Sharpened a drawknife I got from someplace.  Dug up an old Stanley spokeshave and than went on to make one.

Tom, I did notice some of the prices the chairmakers are getting for reamers.  I think one could make a fair profit at $140.  Not that hard to make.

And I have even learned how to spell tenon! :)
Larry, making useful and beautiful things out of the most environmental friendly material on the planet.

We need to insure our customers understand the importance of our craft.

Hilltop366


Larry










I made two maple stools like this.  I like the looks but they are uncomfortable to sit on.  Finish is Livos Kunos natural oil (German $$) but an excellent finish.

Learning, I changed my design.  The seat on this one is very comfortable.  I also spaced the legs out to give more foot room on the stretchers.  The seat is sweetgum with ash legs.  Finish is wipe on Minwax poly.



I think I have the technique down and happy with my present design.  Working on two more seats using walnut crotch wood. ;D
Larry, making useful and beautiful things out of the most environmental friendly material on the planet.

We need to insure our customers understand the importance of our craft.

Stephen1

Very nice work Larry. I like the looks of the last stool.
IDRY Vacum Kiln, LT40HDWide, BMS250 sharpener/setter 742b Bobcat, TCM forklift, Sthil 026,038, 461. 1952 TEA Fergusan Tractor

Tom King

Looks great!  And I like the proportions of the stretchers a Lot better.  I started to say something about the first ones, but decided not to, and I see you agreed with me anyway, without me having to say anything.

samandothers

Larry if you need an in biased opinion on the stool comfort just send me one.  I'll use it and give you some feedback.  I'll just keep the stool for continued testing and feedback!  ;D  Just trying to help you out. 

Larry

A couple of crotch walnut stool seats in progress.




I made a new reamer out of osage orange.  Refined the process of drilling and reaming so it goes fast with little error.

I'm turning legs for the seats now.  Making them a little thinner with fair curves in hopes of making the stool appear to be lighter.
Larry, making useful and beautiful things out of the most environmental friendly material on the planet.

We need to insure our customers understand the importance of our craft.

Tom King

My friends that work for NASA say their definition of an expert is someone who has done something once before.

I'd say you now qualify at someplace beyond being called an expert on this type of chair/stool building.

Larry



Crotch walnut seat and cherry legs makes an interesting stool.  I've refined the drilling and reaming on the seat for the legs.  Happy with the fit and size.

Always tweaking my finishes.  Sanded to 320 and used a mix of Minwax poly, naphtha, and a bit of real tung oil.  I think it looks good and feels good when I rub my hand across it.

Larry, making useful and beautiful things out of the most environmental friendly material on the planet.

We need to insure our customers understand the importance of our craft.

tule peak timber

Beautiful and inspiring work Larry. Can you tell us more about the German finish mentioned earlier in the thread?
persistence personified - never let up , never let down

Larry

I've been using Livos Kunos Natural Oil Sealer.  Easy application, less amber than other oils, and has outstanding wear resistance.  More info can be found here.  Livos
 
The USA distributors are a husband wife team.  Andy's main job is high end cabinets in Idaho.  He uses Livos, I think exclusively, in his work which says a lot for the product.  Betsy handles Livos sales.  Both are knowledgeable and friendly.

Lots of other products in the line up.  Bunch of different stains which work well, lots of brown shades! :D  I tried a few out trying to duplicate fumed white oak.
Larry, making useful and beautiful things out of the most environmental friendly material on the planet.

We need to insure our customers understand the importance of our craft.

tule peak timber

The fumed/grayish is tricky and hard to do.Look at some of Rubio Monocoat products.They respond differently on different woods......
  Larry ,,,your stools are "hot" , taken another way ---- great work-and it shows it ! 8) 8) 8) 8) 8)
persistence personified - never let up , never let down

Larry

Thanks for all the really nice complements guys. :) :)  Gives me encouragement to keep on trying to improve.
Larry, making useful and beautiful things out of the most environmental friendly material on the planet.

We need to insure our customers understand the importance of our craft.

tule peak timber

I reached out to the Livos group. Thank you for the info and the thoughtful build post !
persistence personified - never let up , never let down

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