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Home made biscuits for aligning boards

1584 Views 28 Replies 18 Participants Last post by  HowardAppel
Just saw recent John Heisz video about making home made biscuits. I have some boards to join up for a table top, and want to use biscuits for better alignment/less sanding, and am thinking of the tighter tolerance allowed by home made versus the store bought that are supposed to swell up after gluing. Since the home made biscuits are not compressed, it seems they will swell less and not expand wood at the joint. Or at least it would swell back down after completely drying. Any collective thought on this? Also, thinking of just cutting diamond biscuits rather than bothering with the hole cutting bit.

Any thoughts?
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If woodworking for you is a job and income then your time is valuable and shouldn't be spent on making biscuits of undetermined quality when buying the compressed commercial ones is relatively cheap.
My thoughts are to stay away from Woodworking influencers on YouTube. Everything you need to learn in the craft you will learn by keeping your nose to the grind stone. Shoulder to the wheel. Endeavor to persevere.
Pay very little attention to what others do. Look to the wood for guidance.
Good Luck
How do you plan on cutting the slot? If you don't have a biscuit joiner you may as well save yourself a bunch of time of trying to cut slots and make biscuits the correct size and use a dowel jig and dowels.

If you need a biscuit joiner I have a nice Dewalt that is in excellent condition in a metal case that I haven't used in over 8 years that I would be happy to part with relatively cheap. I'll even throw in a couple jars of biscuits. I have a Domino so that poor thing will never see the light of day again.
I guess I'm actually more concerned about getting a tight fit than the time it takes. Tighter fit = better aligned boards = less finishing work.
I would use a slot cutting router bit and use a spline.
Stop short of the ends so they don't run through.
Cut your splines to the fit the way you want, not so tight you have to pound them in,
just snug enough that they can be pushed in by hand or with just a little persuasion.
The biscuits I use with a slot cutting bit on my router have a good fit. If you're concerned with a tight fit do what Lee Roy suggested. You are using the right size biscuit to match your cutter?
Truthfully, I think its a guy looking for content. I've never seen anything that would make me question manufactured biscuits.

I've never had an issue with alignment, but truthfully I never use them for panels anyway.

Any slight discrepancy, you loose the clamp a bit and hit is with rubber hammer till its flush then retighten.

You should give that no biscuit approach a shot. I only use them if a board is bowed.
bisquit joiners have been around for over 50 years and the manufactured bisquits seem to work quit well.why try and reinvent something so simple and works so well ?
I agree with everything the responders to your post have said. Personally, I don't use biscuits even though I have some. Two things I have noticed in the wood working world is this: 1) some people want to, for whatever reason, make things as difficult as possible. 2) There are people on You Tube who don't have the slightest idea of what they are talking about. I call them yahoos.
I find a lot of You Tubers do videos of things because they can. For me that doesn't automatically convert to I should. Dominos, biscuits and dowels all come with a price, but versus wasting precious shop time making them for the small cost they are. I'll keep buying what I use
If you want a tight fit, leave them out in the humidity for a little while. I've found many that swelled to the point they wouldn't fit the slot. As for the glue swelling them up, if you're worried about that just don't use any glue on the biscuits.
If you want to compare costs of store bought verses DIY. Make 85 of the #20 biscuits yourself, BUT, KEEP TRACK OF TOTAL TIME SPENT, even if you used a scrap piece of wood. Now compare the cost of Store bought, 85 pieces, #20 biscuits @ about $6.50

How much time is wasted or lost to save $6.50, You just lost over $30 at least in time.
Yeah, this isn't a time versus money thing, or at least not directly. This is a 7' table top glue up that would go over better with some guiding joinery. One could use a domino for that, but enter money into the equation and I don't want to buy one. I would be using the biscuit joiner instead of the slot cutting bit on a router, however now that you mention it, I'm liking the slot cutting bit more and more. Store bought biscuits fit too loosely for my purpose, and the last time I used my biscuit joiner (Ryobi), the height of the cut wasn't terribly even. I also have a zillion 1/4" loose tenon pieces that yes, I made on my own, and no it didn't take very long. Slot cutter = domino with one degree of freedom. Thanks LeeRoyMan and Corelz!
... Store bought biscuits fit too loosely for my purpose, and the last time I used my biscuit joiner (Ryobi), the height of the cut wasn t terribly even. - MarkCh
IMHO - If you can not cut an accurate slot for biscuit location, need to perfect how to use the tool.
Otherwise, might as well use buttermilk biscuits for alignment.

+1 Moisture content vastly impacts initial biscuit fit. They will quickly expand when wet with glue, fill the entire slot.

+1 Use a spline and cut slots to fit if you want tight fit. Can use router slot bit, or table saw.
Suggest you round the edges of glue up splines. If boards are not perfectly straight along entire length, square edges will crush or splinter and can ruin a glue up; or at very least be a mess to clean up when they do not fit perfect.
There has to be some tolerance, or slop between the insert and slot.
With out extra room, there is no where for glue to reside. So any effort to make a perfect fitting biscuit/spline alignment system; will always be compromise between ease of assembly on long parts or proper gap to create a proper glue joint.
That is one reason the common recommendation is biscuits on edge glue up (were you don't need strength), and splines on short edge grain joints (where you need extra strength).

IME - even with perfect slots, and perfect biscuits, if you put too much glue on 1 side of biscuit; you end up with slight mismatch in edge joint. So can not complain when an biscuit aligned edge joint is 1/64 too high/low, as that is the price of tolerances in a quick and easy alignment system. If the misalignment is more than 1/32" then check your slot cutting and make sure you are using the right size biscuit for saw blade in joiner.

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this issue is way over thought.every bisquit ive used with my dewalt has been snug.with the glue it swells very tight.try to pull one out after 5 minutes ! ive used them for alignment of boards many time with no problems.forget about it and glue up your the time you get done making home made bisquits ill have the top done and ready for the table base.have fun ?
Splines done right work better than biscuits in my opinion.
I just did a bunch of them in plywood, they came out flush enough to sand without going through the veneer.
I made the splines out of baltic birch.
And as the captain said break the edges of the spline, and I break the edges of the slot as well.

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I have the Katana slot cutting bit from MLCS and a #20 biscuit fits snug in it. Maybe there's some play in the Ryobi biscuit jointer that makes an over sized slot.
I have the Katana slot cutting bit from MLCS and a #20 biscuit fits snug in it. Maybe there s some play in the Ryobi biscuit jointer that makes an over sized slot.

- corelz125
ryobi…..well that could be part of the problem ?
figure there is nothing wrong with knowing how to make them in a pinch, but for a stable supply the store bought work just fine, and here in Arizona, humidity is not an issue for 9 months outta the year.
happy friday,
rj in az
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