Thread: Biscuit or tenon/mortise for circus strength

Mortise and tennon. Biscuits won't give any strength.
The type of timber will be the main factor determining strength.
A straight grained hard wood would be best.

thx a lot for that it is really helpful.

what about floating tenon ? I have found different point of view on their strength... What do you think ?

Floating tennon would be fine. Still has plenty of long grain to long grain glue area.

done! i ll give that a go and let you know. thx a lot for your help

Don't forget the WIP c/w plenty of photos. You know how we like photos

Sooooo here it is. my first ever experience with tenon and mortises :

I came across a few issues that i d like some help with

IMG_2601.jpgIMG_2602.jpg

First of all there is a few messy bits and extra mortises that we can see ... I got too exited and went messy / dumb, it wont happen again.

I did struggle a lot to get the mortises aligned with each other and have the timber perfectly flushed on each intersections, is there a technique / jig to help that ?

Also after gluing the whole thing it is fairly strong but still squeaks when i use the chair on an angle is it "normal" can it snap? or should i put 2 big T brackets on the middle back part of the chair ?

let me know what you think

jon

You've done very well for a first effort

How did you make the mortice and tennon joints?
To keep everything flush and neat you need to mark the outside face of each component and reference everything from that face.
A few more details on construction will help us answer your other questions.

thx NCArcher,

I made the floating tenon out of a timber that was the same width than my router bit ( 1.8cm ) and routed it so it s rounded the same as the mortise.

for the mortises i used my router of course and drew and incredible amount of marks/lines on my table / home made press as jigs so i would (almost) constantly do (almost) identical mortises. ( i can take a picture of it if you d like

for the dimensions
- the main timber is 4.2cm x 4.2cm square.
- tenons are 4cm long x 1.8cm high x 3cm width
- mortises are 1.8cm wide x 3cm long x 2cm depth

I had to do a three dimensional frame, i think this is how you guys call it for the intersections which i could not do in the middle of the timber. i had to go a bit off centre so the tenon would t clash, i m definitely not sure about this part.

is 2cm deep enough for my mortises ?

ps : i hope i am being almost clear with everything i m not really familiar yet with all of that

30 x 18 sounds pretty good for the tennons but I would extend them to around 30mm in each side giving a floating tennon size of 60mm. For the top joint where the tennons clash, move them to the outside of the leg with only a 5-6mm wall. You can then route the full depth and mitre the tennons where they meet. If that makes sense.

ahh i was gonna do that but wasn t sure if it was safe to mite the tenon in the inside. i gess it doesn t matter when it s all glued. i ll make the second chair next week probably and let you know. thx a lot for your help.

Having updated my technic / tools i thought it would be nice to show you guys the new version : circus chair 2.0

20140404_144611-1.jpg20140404_144840-1.jpg

let me know what you think

The chairs look great.
I should point out that your chair sitting technique could use a bit of work. Your doing it all wrong.

Nice slippers.

I once read that biscuits have the strength of damp Weet-bix. Worth remembering. They are really only good for aligning timber, typicall boards that are to be edge jointed.

You have done extremely well for a beginner, great job!

You need to be able to make the M&T joints as snug as possible before gluing. Once the glue sets, it will be the timber that breaks before the joint fails. This will not happen if there are gaps between the mortice and the tenons

NICArcher : thx for the compliment my partner ( in the picture ) will love to know that her slippers are appreciated

Dengue : you pointed out the exact issu i m confronting. I m doing the floating tendons out of 18x30 ( mm ) then round it over BUT, my round over bit doesn't do the same curve as the straight bit used for the mortises so always end up with gaps on the diagonals of the tenon. Any suggestions ?

thx guys it encouraging