Thread: Why not stronger biscuits?

When i was working for someone else we used biscuits everywhere. Ian has got it wrong in only one way in my mind. They locate and drastically reduce clamping times. This is not such a big problem in the home workshop but when you can clamp for only 1 1/2 hours in a professional shop it really removes a big choke point in production.
If you want strength use a traditional joint or a ply spline. A round hardwood biscuit has 2 problems in my mind, you have to make them and they may not glue as well to the timber you are joining as the timber does to itself.
Did you have a particular joint in mind, or is it a general thing?

OK Jill some comments

cutting a semi-circular slot is pretty hard as the centre of the cutter gets in the way -- that's one of the reasons a biscuit slot is only part of a circle

biscuit joints are really for joining manmade baords together -- often these joints are "pulled-up" with screws

biscuits are compressed during manufacture so that they will swell with glue to become a snug fit in their slots -- if they were a snug fit to begin with getting and some glue into the slot would be neigh-on impossible

you're better off sticking with loose tenons

thanks ewan and ian for your wise comments. Yes, I agree that a small semi circular slot would be just about impossible.

The joint I had in mind was something to strengthen the mitre joints of picture frames which can hold a heavy sheet of glass, without having to resort to the V nails and risk of damage to the timber.

Jill,
What I did once was to go to a hobby/model shop and get some thin ply...you can the stuff down to less than a millimetre in thickness and it's really strong stuff... and glue pieces across the back of your corners. You could cut either triangular gussets or "L" shaped pieces if you need to provide for replacing the glass at some stage.
Depends on whether you think it'll look too"agricultural" but if it's thin enough and you set it back a bit from the edges it may not show.

Just a thought

Ian

Good Morning Jill

Have you seen the corner methodology used on stretcher bars for oil paintings? (ie the frame that the canvass is stretched across before painting starts.)

Art Spectrum Stretcher Bars @ Artstore - Art Supplies | Artists Materials | School Arts Supplies | Photo Printing

Stretcher bars are universally available at all art supply stores - should be one or more near you - and they might give you an idea or two.

Fair Winds

Graeme

Originally Posted by JillB

thanks ewan and ian for your wise comments. Yes, I agree that a small semi circular slot would be just about impossible.

The joint I had in mind was something to strengthen the mitre joints of picture frames which can hold a heavy sheet of glass, without having to resort to the V nails and risk of damage to the timber.

You could do mitred half-lap joints and pin them with a trenail, either all the way through as a feature, or blind so it looked just like a mitred joint.
food for thought.

Hi Jill,
I certainly wouldn't use bickies on mitres like that. Glue up then put in a spline on the corner. You can make the cut with a handsaw, set a jig for the tablesaw or even better cut it with a small dovetail cutter and make a dovetail spline.
The other option is a twin M&T, not sure on the actual name of the joint and the book i need to find out is in a box somewhere....

This is close but not the one i was thinking Making a Mitered-Face Mortise-and-Tenon Joint | Galoototron

Here is a quick sketch, sorry i couldn't get my head around it exactly, but both pieces have a mortice and a tenon, which gives a huge face to face gluing area.