# Biscuits seem too thin for the slots



## mspain77 (Mar 26, 2016)

Hi everybody,
So I'm out in the shop trying to have a nice relaxing Sunday gluing up a table top and it's not going according to plan. I'm using biscuits for the first time as we've just uncovered my dad's old biscuit joiner while cleaning up my mom's garage. I never do anything in the shop without researching it on YouTube and watching a variety of videos. It seems that every video I've watched shows the guy tapping the biscuits into place with a mallet or forcefully pushing them in. Mine are loose and seem to be too thin for the slots I've cut. If I pick the board up and turn it over the biscuits will fall out.
I'm using General brand biscuits, #20 and I've got my joiner set to the right depth. I can't imagine that these are inferior biscuits that were cut incorrectly, so what am I doing wrong? Is there a trick I don't know about? I just don't see how these biscuits will aid in lining up my boards and keeping them flush when there is so much play in the up and down direction. I know they are meant to have room to adjust side to side. 
Any help would be much appreciated. I'm kind of at a stand still until I figure this out and get this top glued up the right way. Thanks in advance.


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## bandit571 (Jan 20, 2011)

Because the biscuits will swell in the glue, sometimes they will cause a "bulge" to appear where every one is in a joint. I rather they would be a bit loose. When you add the glue into the slots, it allow a bit of the glue to slip around the biscuit, as well.


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## 000 (Dec 9, 2015)

Some questions. 
Did you make one flawless plunge cut or did you go over it a couple of times, possibly widening the slot?
What is the size kerf of the cutter? (I believe it should be 5/32 or .156)

My biscuits fit firmly in the slot, as you were saying. 
They sound too loose to use, but you could do a sample hole and glue the biscuit into one half and see if it swells enough. 
Also note how fast the biscuit expands to see if it will expand fast enough to help with your alignment.
Mic the biscuit to see what thickness is. 
Maybe go to the big box store and mic some Ryobi biscuits (or what ever brand they have) to compare to. 
It could be General biscuits just run thin.

I use a Lamello cutter and Lamello biscuits, and fit is always good.


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## MadMark (Jun 3, 2014)

Biscuits are nominally 1/8" as are the cutters & slots. The biscuits started as 1/8" but were overdried & pressed to be loose in the slot. Use a biscuiter instead of a router to cut the slots.

I use a glue brush to wet 1/2 of each biscuit with glue and insert into the top piece. By the time I've glue painted and coated the slots the top biscuits have expanded enough to hold and everything just slips together.

M


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## 000 (Dec 9, 2015)

> *Biscuits are nominally 1/8" as are the cutters & slots. *
> M
> - Madmark2


I disagree!


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## Andybb (Sep 30, 2016)

> *Biscuits are nominally 1/8" as are the cutters & slots. *
> M
> - Madmark2
> 
> ...


Why do you disagree? Biscuits are normally or nominally 4-5 32nds (3-4mm) and are designed to swell with water based glues.


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## 000 (Dec 9, 2015)

> *Biscuits are nominally 1/8" as are the cutters & slots. *
> M
> - Madmark2
> 
> ...


I could be wrong, but I have never seen, or used, a biscuit that is .125 thick. 
Can you show me where you got this info?

Styandard biscuits #0, #10, #20 are 4 mm thick (.157) The thinnest I have found are .148 
(The H9 which is a mini biscuit is only 3mm thick. I didn't figure this biscuit because it's not standard)

Standard cutters are 4mm


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## pintodeluxe (Sep 12, 2010)

Bandit said the biscuits will swell and telegraph their location. This is only a problem on 1/2" or thinner stock (or if you forget to center the slots).

I find the Dewalt brand biscuits fit tighter than other brands. They work great with my Dewalt biscuit joiner, and you can find them at Lowes.

I like and use biscuits all the time, but I don't find them useful for panel glueups. 
It's actually easier to get flat panels with just glue and clamping cauls.


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## GR8HUNTER (Jun 13, 2016)

WELL MY BISCUITS …..are about 1 inch thick …golden brown ..I usually like to eat them with butter and jam on them …or sometimes jelly …..I know I know but couldn't resist ..if you want to boot me for being like Ducky …I totally do understand :<))


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## bc4393 (Apr 10, 2015)

I swear you get a bunch of dudes together and you end up with a biscuit measuring contest.  They should not fit snug when you dry fit them. LIke was said it could bulge and slit the wood. I actually sand mine down a bit to make em drop in without any friction. Slather em up good, they will swell. Don't worry about it.


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## bonesbr549 (Jan 1, 2010)

....does my heart good to watch this..we agree don't we. For me had one and sold it. Not good for anything other than alignment. Once you've done a few glueups, even thats not required. Skip em.

Ohh, they will swell if you put the glue to em, but again they not worth the hassle. Sell it and make a few bucks.


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## Andybb (Sep 30, 2016)

Well, after all that, I think the consensus answer to your question is…
1. They shouldn't fit snug when inserted in the hole without glue. 
2. They really don't add any strength to the joint and are mainly good for alignment on boards 3/4" and thicker. I use them on thick boards like live edge work but only for alignment and only if one face (usually the top) is flat. I turn that side down so I know the slot is at the same depth on both boards. If I've got a 5 or 6' long glue up I might use a few but that is only to aid in alignment. Planing is still sometimes required.
3. They do swell once glued which is why they are loose without glue. 
4.Standard thickness is 4mm which is roughly 1/8".
5. When 1" thick biscuits are cut in half some material is lost but the jelly usually compensates for that.


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## 000 (Dec 9, 2015)

I forget how stupid I am.
Although, I have probably used over 5000 biscuits in the last 35 years and never had any of them split my wood or leave buldges in the surface.
I'll leave it to you all that have read so much about it.
Peace out!

(4mm which is roughly 1/8") Love it… lol


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## Kirk650 (May 8, 2016)

I'm with jbay, having used a bazillion biscuits without the first bulged or split board. And they are extremely useful for alignment, though I still use cauls. If anyone needs fat swollen biscuits, I have plenty. Time and humidity will fatten them up, like it or not. I hear that heating or microwaving them will slim them up, but I haven't tried it.


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## firefighterontheside (Apr 26, 2013)

The loose ones don't bother me. It's the tight ones that I don't like. I'm afraid they will swell before I have it put together and then they will hold the joint apart. If I can't put them in with my hands I throw them out.


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## mspain77 (Mar 26, 2016)

Well that was a lot of feedback. Thanks guys. 
This IS my first time using them, and I'm not looking for strength, just alignment with them. I am using a Porter-Cable biscuit jointer, and I previously used a Freud on the same table top and the results are the same with both. When I cut my slots, I did so with one plunge, so I did not widen the slot through sloppy work. I guess I'll just glue up half of them and put them on one side of each board, and then dry fit them together before final glue up to make sure they line up well. 
Thanks again guys.


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## BenDupre (Jan 23, 2017)

Ah like my biscuits with mustard… um hmmm..


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## Andybb (Sep 30, 2016)

> (4mm which is roughly 1/8") Love it… lol
> - jbay


What did I miss? Isn't 3-4mm about 4-5/32nds?


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## Andybb (Sep 30, 2016)

> I forget how stupid I am.
> Although, I have probably used over 5000 biscuits in the last 35 years and never had any of them split my wood or leave buldges in the surface.
> I ll leave it to you all that have read so much about it.
> Peace out!
> ...


What did I miss? Isn't 4mm about 4-5/32nds?

*4 mm 0.1575″ 5/32″*

Here in the US biscuits are listed and sold as 1/8" vs. 4mm. Sorry. Didn't mean to offend you.


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## 000 (Dec 9, 2015)

No worries, Not offended.

*4 mm 0.1575″ 5/32″*

*1/8" = 0.125* .......Your right, they are "roughly" the same

Show me ANY biscuits "Listed" at 1/8"...Here in the US
Go buy a new cutter, Here in the US, and tell them you want 1/8", or roughly 1/8", and see if your biscuits fit.
----------------------------------------------------------------

The perfect fit: (Hand Pressure)


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## DrDirt (Feb 26, 2008)

> Because the biscuits will swell in the glue, sometimes they will cause a "bulge" to appear where every one is in a joint. I rather they would be a bit loose. When you add the glue into the slots, it allow a bit of the glue to slip around the biscuit, as well.
> 
> - bandit571


I have not experienced any 'telegraphing' of biscuits to the surface.

In all the discussions I had seen before, the concern was having a divot in the surface where each biscuit is, because the biscuit swells with the glue and moisture, but ultimately shrinks back down.

So the telegraphing is supposedly caused by surfacing the tabletop, and getting it level, before the biscuit shrinks back down.
Maybe my boards have all been thicker… but I have never had it happen, and haven't seen it. Even the discussion at Highland, has no pictures
http://www.highlandwoodworking.com/whenbiscuitjointsgobad.aspx


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## Kazooman (Jan 20, 2013)

One last thing to check it the actual dimension of the slot. A bent cutter could cut a wider than intended slot. I've never actually heard of this happening, but you could check.


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## wormil (Nov 19, 2011)

I've been hearing this biscuit divot story since Norm was still on TV and I've never experienced it, have never seen a picture or video showing it. I always assumed it was "hypothetical" and just got repeated like it was real. Maybe in really thin stock it could happen, theoretically.


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## 000 (Dec 9, 2015)

I have a wood top (some one else made) that I replaced, that has the divots showing every where there was a football. I'll see if I can get some pics that will be good enough to see it.
I circled the divot spots, there hard to see but they are there. 
Actually, there's one everywhere I put the blue tape, but you have to get the light and angle just right to see them.


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## wormil (Nov 19, 2011)

I'll have to take your word on it. I would rip the table open to see what is going on because I've never had that happen. My guess is the biscuits are off center and too near the top. This would be a good project for a youtuber, do a bunch of test glue ups and see what it takes to make the myth come true. Probably get a bunch of views.

I turned your picture.


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