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biscuits or mallet?

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Forum topic by Travis posted 06-06-2019 03:18 PM 746 views 0 times favorited 41 replies Add to Favorites Watch
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Travis

264 posts in 189 days


06-06-2019 03:18 PM

Hi all,

I’m preparing for my first large glue-up. I’m edge joining some planks to make a large panel. Pieces are about 5’ by 6” and final size will be 5’x18”. I’ve glued up smaller panels, but never anything as long as 5’. I’m worried about keeping the planks lined up flat on the long edge over such a long distance. I’ve seen some woodworkers use a rubber mallet during the glue up to pound things down where they need to be and I’ve seen some use biscuits.

I know biscuits don’t add to the joint strength, but have heard they can be really helpful in aligning and maintaining position during glue up. For those of you who have used biscuits, are there any downsides? Does it complicate the glue-up any? With the mallet, it seems you have some flexibility in positioning the wood, whereas with the biscuits things are more locked into place, for better or worse.

-- The plan is wrong; my finished piece is right.


41 replies so far

View CWWoodworking's profile

CWWoodworking

528 posts in 601 days


#1 posted 06-06-2019 03:34 PM

IMO if the boards are not flat enough to get flat with clamps, you need flatter boards. I never use biscuits.

View Fred Hargis's profile

Fred Hargis

5595 posts in 2915 days


#2 posted 06-06-2019 03:48 PM

The biscuits are useful for alignment. The only downside might be they should be more or less centered across the thickness. If not they swell a little, then some folks sand down the swelling (on the surface) then the biscuits shrink and you wind up with football shaped divots in your top. The problem I’ve had using a mallet to fine tune the alignment is you need a flat surface to lay the workpiece on to line things up. For me that piece is usually sitting on a couple of clamps, which doesn’t always work out that well.

-- Our village hasn't lost it's idiot, he was elected to congress.

View JayT's profile (online now)

JayT

6228 posts in 2633 days


#3 posted 06-06-2019 03:53 PM

Use some clamping cauls. They will help align all three boards for a good joint without biscuits or having to pound on them.

Edit: Here's an article to read up on them.

-- https://www.jtplaneworks.com - In theory, there is no difference between theory and practice. In practice, there is.

View Travis's profile

Travis

264 posts in 189 days


#4 posted 06-06-2019 03:54 PM



The biscuits are useful for alignment. The only downside might be they should be more or less centered across the thickness. If not they swell a little, then some folks sand down the swelling (on the surface) then the biscuits shrink and you wind up with football shaped divots in your top. The problem I ve had using a mallet to fine tune the alignment is you need a flat surface to lay the workpiece on to line things up. For me that piece is usually sitting on a couple of clamps, which doesn t always work out that well.

- Fred Hargis

Thank you for sharing your experiences. I had not heard about the swelling issue. If the biscuit does end up swelling, should I just not sand it down and trust it will shrink?

I have similar concerns about the mallet approach. I also envision myself playing a never ending game of “whack-a-mole” as my hammering in one spot causes displacement in another.

-- The plan is wrong; my finished piece is right.

View Travis's profile

Travis

264 posts in 189 days


#5 posted 06-06-2019 03:59 PM



Use some clamping cauls. They will help align all three boards for a good joint without biscuits or having to pound on them.

Edit: Here s an article to read up on them.

- JayT

I’ve used cauls in the past for smaller panels. I anticipate that I would need probably 4 sets at least for a panel this long, and that starts to get crowded and is a lot of clamps I have to manage before the glue starts to dry. I was hoping biscuits would simplify things.

-- The plan is wrong; my finished piece is right.

View PPK's profile

PPK

1439 posts in 1231 days


#6 posted 06-06-2019 04:07 PM

I’ve used all the methods, and they all work fine, depending on the situation.
One thing to keep in mind if you do decide to use biscuits, is that you need to think about their placement. If you end up shaping the glued up panel and cut into a biscuit, it’ll look pretty bad.

-- Pete

View ArtMann's profile

ArtMann

1399 posts in 1238 days


#7 posted 06-06-2019 04:12 PM

In my opinion, the most fool proof method would be to use dowels and a good quality dowel jig. I am not talking about the cheap self centering kind but rather the type that references one surface for flush and has an indexing mechanism for longitudinal positioning. I use the Dowelmax but there are a few other good ones. None of the good ones are cheap.

View Hondo03's profile

Hondo03

30 posts in 251 days


#8 posted 06-06-2019 04:23 PM

I have used biscuits for years when gluing up panels and I have never experienced an issue with “swelling”. The biscuits do offer help in aligning the boards to be joined and keep them the way you have oriented them during the jointing/planning process.

View SMP's profile (online now)

SMP

1199 posts in 328 days


#9 posted 06-06-2019 04:31 PM



Use some clamping cauls. They will help align all three boards for a good joint without biscuits or having to pound on them.

Edit: Here s an article to read up on them.

- JayT

I would also recommend cauls. Biscuits “can” help align things, but depending on what kind of clamps, most people want to “make sure” the clamps are nice and tight, inadvertently overtightening and putting a bow/concave into the glue up. Biscuits don’t help that at all.

View LesB's profile

LesB

2131 posts in 3865 days


#10 posted 06-06-2019 04:40 PM

I have used biscuits without any problems but another nearly fool prof way is using a router glue joint bit to cut a inter-locking edge on the joining boards. This also increases the gluing surface.
Here is a Woodworker’s Journal article on it. https://www.woodworkersjournal.com/making-router-bits-glue-joint-bit/

-- Les B, Oregon

View HokieKen's profile (online now)

HokieKen

9974 posts in 1560 days


#11 posted 06-06-2019 04:46 PM

I’m a fan of just get it as good as you can then hand plane it flat. I have yet to glue up a panel that came out of the clamps ready to use. Biscuits are helpful for alignment, as are cauls but, IME, a handplane and/or scrapers still have to touch it afterwards. Which, may sound like extra work but, it takes a lot less time to make a few swipes with a hand plane than it does to cut a bunch of biscuit slots ;-)

-- Kenny, SW VA, Go Hokies!!!

View Fred Hargis's profile

Fred Hargis

5595 posts in 2915 days


#12 posted 06-06-2019 04:52 PM

Thank you for sharing your experiences. I had not heard about the swelling issue. If the biscuit does end up swelling, should I just not sand it down and trust it will shrink?

- Travis

I have only had this occur on plywood, which I didn’t sand down; and after the moisture in the glue evaporated, the bumps went away. I’ve heard the same from guys who use them in hardwood and have that happen. The bumps are usually because (IMHO) the biscuit slots are placed too close to the surface. So if I ran into this, I would wait a few days and see what happens, then smooth it out.

-- Our village hasn't lost it's idiot, he was elected to congress.

View Travis's profile

Travis

264 posts in 189 days


#13 posted 06-06-2019 04:59 PM



I ve used all the methods, and they all work fine, depending on the situation.
One thing to keep in mind if you do decide to use biscuits, is that you need to think about their placement. If you end up shaping the glued up panel and cut into a biscuit, it ll look pretty bad.

- PPK

Yikes, that would be unsightly! I won’t be shaping this piece.

-- The plan is wrong; my finished piece is right.

View Travis's profile

Travis

264 posts in 189 days


#14 posted 06-06-2019 04:59 PM



I have used biscuits for years when gluing up panels and I have never experienced an issue with “swelling”. The biscuits do offer help in aligning the boards to be joined and keep them the way you have oriented them during the jointing/planning process.

- Hondo03

Thanks for your experiences

-- The plan is wrong; my finished piece is right.

View Travis's profile

Travis

264 posts in 189 days


#15 posted 06-06-2019 05:01 PM



I m a fan of just get it as good as you can then hand plane it flat. I have yet to glue up a panel that came out of the clamps ready to use. Biscuits are helpful for alignment, as are cauls but, IME, a handplane and/or scrapers still have to touch it afterwards. Which, may sound like extra work but, it takes a lot less time to make a few swipes with a hand plane than it does to cut a bunch of biscuit slots ;-)

- HokieKen

That does sound simple. I am still developing my hand plane skills so at this point, for a meaningful piece, my post glue-up touch-up is the ROS :(

-- The plan is wrong; my finished piece is right.

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