biscuits VS mortise and tenon

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Blog entry by needshave posted 02-29-2016 05:11 PM 695 reads 0 times favorited 3 comments Add to Favorites Watch

I have never been a real believer in the use of biscuits in the glue up of large table tops or wider sections in general. Especially where end grain and long grain must be glued together. However, I have never used them either.

I’m very old school and have always defaulted to Mortise and tenon and have often pinned those joints with dowels. It strong, its reliable, if time and proper procedures are used to make the joints properly. That’s the downfall this construction method is very time consuming.

I have looked at a number of biscuit cutters and the amount of penetration the biscuit allows, attended a few demonstrations and I remain unconvinced that I wont see distortion of the lamination over time, if not the breaking of the biscuit its self. It seems like a great alignment tool, and where you need to only rely on the strength of the glue, it might be ideal.

The time savings, using biscuits is impressive, but still. I’m sort of lazy, I want to do it once. I don’t want to fix it.
What are you’re thoughts? Any real experiences I can draw upon?

3 comments so far

View pintodeluxe's profile


4824 posts in 2231 days

#1 posted 02-29-2016 05:37 PM

I have used biscuit joinery extensively, and am a fan if used in the correct application.

Tabletops and large panels: Don’t bother using biscuits. They are not needed for strength and actually complicate alignment (especially if your boards aren’t perfectly straight and flat).

End grain to long grain butt joints: This is a perfect place to use biscuits. Increases strength in an otherwise weak glue joint. Example… web frames for dressers and case work.

Edgebanding plywood with hardwood strips. This is a great use of biscuits. I find it much quicker and easier than cutting a tongue and groove to register the edgeband. In this case the biscuits actually help with alignment.

Heck I even use biscuit cutters to make slots for locking drawers. The barrel lock tab fits perfectly in a #20 slot.

No, I do not use biscuits in place of M&T joints.
No, I would never join rails to legs with biscuits as a primary table joint.

Overall, I like and use my biscuit joiner on a few choice spots on almost every project.

-- Willie, Washington "If You Choose Not To Decide, You Still Have Made a Choice" - Rush

View MadMark's profile


965 posts in 870 days

#2 posted 02-29-2016 05:50 PM

Lamination distortion doesn’t really show up. The biscuits are usually overdried and initially loose in the slot. They will swell with glue but not enough to show.

As for failing in use, biscuits are cut on a 45° so even if they crack they will retain lateral & pullout resistence.

Spend the $$ on the porter-cable 557 instead of a cheap biscuiter. Cheap units have bad blade bearings that rapidly get sloppy and your slots as well.

Technically a biscuit is a floating tenon. So you’re still making a M&T joint. I’ve got a biscuited table that I made 20+ years ago that is still solid as a rock. It does have a lower shelf and rear stringer but those are biscuited too.


-- Madmark -

View Todd A. Clippinger's profile

Todd A. Clippinger

8901 posts in 3517 days

#3 posted 02-29-2016 07:35 PM

I use biscuits to aid in alignment.

Interesting point that pintodeluxe makes is that biscuits complicate alignment if the boards are not flat and straight, but I use them to aid and keep alignment during glue-up when boards are not flat and straight. 2 different view points and 2 different strategies, from 2 qualified craftsmen.

I have noted biscuits telegraph a depression if I use them and then mill the material too soon while the biscuit is still swollen, then as it and the wood dries it shrinks, thereby leaving the depression.

This was early enough in my career I took note of it, looked at some past projects and found it existed there too. But it could only be seen if a raking light was coming across the surface.

The reason I noticed it in the first place was that I built a fireplace surround and the when passing by the mantle, light coming in from the window across the room gave just the right lighting that I noticed it but I certainly never mentioned it to the clients;)

After that, I changed from relying on biscuits to aid alignment to the Festool Domino because they do not swell the same way biscuits do.

Dominos add strength in a joint in a way that biscuits cannot in 2 intersecting pieces of wood, for instance a frame for a cabinet door or passage door.

I still use biscuits though, another contractor came to my shop recently and we biscuit jointed 2 pieces of 1/2” baltic birch together to make a piece wide enough of the back panel of built-in bookcases. The joint was perfect the full length, we let them dry for a day, then finish sanded and painted. No need to worry about depression in that situation, being that it was in the back of a bookcase, there would never be any raking light to expose it. As for the joint, it was absolutely invisible.

-- Todd A. Clippinger, Montana,

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