Attaching legs to a slab to make a bench

[flywelder]

I want to build my first ever slab bench, and i am held back because I am not sure how to attach the legs to the slab. I have seen benches with tree branches as legs and these were I am guessing, turned round on one end and then fitted into a hole in the slab. that would work but how would I turn the ends round?
Are there other methods, that are strong and durable?
Are there easy yet strong means to attach legs?......keep in mind this will be my first, and I have what i would say, are advanced basic skills and understanding of wood working.. None of my projects have been on a par that could be sold.....

The bench will be finished with urethane and sit outside, at my house.
I welcome all your suggestions and pictures.... yes, for me, pictures help to understand a lot!
Thanks

 

[McRabbet]

David,

I made a White Oak slab bench for a neighbor a few years ago and used straight grained pieces of an 10/4 slab from the middle of the log (the bench was about 12" wide and a section of the log cut parallel to the pith about 6" thick). The 10/4 slab was the next cut above the bench cut and I cut square stock from the sides of it so the grain was essentiall vertical. We trimmed those into 24" blanks and rip cut the corners off the blanks at a 45 to form octagonal leg blanks. I actually turned the last 4" of them into 1-1/2" round tenons, but they could have been shaped on a stationary belt sander to form the tenons. The seat slab was drilled at an angle by eye with an 1-1/2" forstner bit in my corded 1/2" drill (hold on thight, Nellie!).

Here are some pics of the results:

The finished bench (before trimming the leg ends)

View image in gallery​

My neighbor Jim tests the bench for strength

View image in gallery​

My dog Badger gets a Shop Dog's reward

View image in gallery​

 

[mkepke]

Lots of options:

You can use tenon-cutters like these

...or you could drill the end of the legs to accept a length of store-bought dowel, then drill a matching hole in the slab seat

..or you could make the legs out of slabs:
a) form a tenon in the end of the legs and cut a matching mortise in the seat-slab or
b) use a continuous tenon and a dado in the seat-slab or
c) use a butt-joint between the slab legs and seat-slab but reinforce by drilling holes for dowels through the slab-seat, into the slab-legs.

-Mark

 

[Truefire]

David, if you have a wood lathe that will accept at the least 21 inches between centers you should be set, for you could very easily chuck the legs between centers and turn a 1" tenon which is about the typical size tenon on a smaller stool or chair leg. However it certainly never hurts to make it larger in diameter to ensure it will suffice under load.

Next if you don't have a wood lathe then you could invest in a tenon cutter that fits into a power drill such as the G-08-837 $81.00 7/8” tenon; up to 2 ¾” tenon length on this site. However these can be pricey and you may not desire to spend the monies on a tool of this capacity that may not be used very much.

Your next option, which would be inherently cheaper and would allow for your woodworking skills to truly shine would be to do as Mcrabbet stated: simply cut your leg tenons as close to the diameter as you can get them by cutting octagonally in that area by using your bandsaw and then belt sand to the appropriate cylindrical tenon size sought after. just take your time and you should be able to obtain the tolerances that you are looking for.

You could make a simple triangular jig to use as a guide for the proper alignment of your drill when drilling the tenon sockets by simply cutting a piece of 3/4" plywood , better yet glue two similar pieces together or something similar into the shape of a right triangle. The longer hypotenuse leg would of course need to have the appropriate angle that you desire your sockets to be drilled. You would simply rest your drill against this aid as you drill your socket.

just take your time when drilling with the forstner bit and using this guide, you might want to clamp the guide in place if you have clamps that are capable of holding perpendicular woods

if i remember correctly i want to say that 9 degrees is the preferred angle of approach for legs, someone correct me if i am wrong. so David the triangular guide is not drawn to scale obviously, just drawn to help you picture what i was attempting to convey

of course leave your chair legs a little longer than you need to allow for adjustment when the legs are glued and fastened in place

chris

 

[Mike Davis]

Just do like Norm and use some glue and a few pin brads till the glue dries.
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Or you can come up to my place and use my lathe if you like.

 

[Len]

If you want to go real Neanderthal, you could always drag out the shaving horse and use a draw knife and spoke shave to round the ends of the legs. After all, they call it a SPOKE shave for a reason. :gar-Bi

Len

 

[flywelder]

Awesome tips and suggestions and photos! These all help tremendously!

before we go further tell me how I will keep the legs in the slab if i go the turned leg route? Wil i secure them much like a handle is in a axe and hammer?......which I have not done.

 

[Mike Davis]

Three ways... Taper the leg and the hole then force fit and trim top off, straight line hole and leg - cut slot in leg - wedge either from top or hidden in stopped hole lastly straight hole and leg fit snug and glue.