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The standard 5/32" biscuits seems a bit thin for a strong joint for thicker boards. A Feastool seems like the perfect tool, however it is a high price point for my volume. I have a 1/4" slot cutter router, however would prefer not to make custom biscuits if possible.

Is there any manufacturer that makes round or thicker than standard (1/4" thick or more) joiner biscuits that I'm missing?

It seems MLCS comes closest with their #H-9, and according to their support no long available #11, Biscuits or Feastool's 6mm Tenons.

Side note: while writing this question realized making a two biscuit cuts parallel to each other would do the trick too.

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    If you are edging joining two pieces of wood, why don't you use a spline joint. You have the router. Just cut matching slot on each piece. Insert a matching spline piece. This would be stronger than a biscuit joint. See example of <a href="youtube.com/… "> How to make a Spline Joint </a> here. Apr 30 '20 at 22:57
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    1/4" spline can be found here, <a href=homedepot.com/p/… title=”Source of Spline”>Source of Spline<a/> or other BigBox stores. May 1 '20 at 0:43
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    Instead of custom or unusual/atypical biscuits it is indeed far more common to just use a pair of biscuits instead as you figured out while writing. That said, you're asking about strength primarily right? In what situations exactly? If you are talking about edge jointing in fact biscuits are alignment aids only there. They only provide the joint, or add strength to the joint, in mitres and end grain | long grain joinery situations.... but I should mention that they are actually weaker than all the alternatives, including dowels if they're done properly! [contd]
    – Graphus
    May 1 '20 at 15:33
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    Biscuits are still strong enough for normal service in a great many cases, especially in solid wood, but if strength is the primary consideration it's worth looking at alternatives to biscuit joinery.
    – Graphus
    May 1 '20 at 15:34
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    @Programmer66 and @ the OP, while those are labelled as splines they're not actually splines in the normal use of the word in woodworking circles. Splines, for strength, must have the grain aligned at right angles to the joint. Those 'splines' are in effect like long lengths of Dominos, and while they're perfectly suited to the same common uses as Dominos e.g. mainly for mitres and 90° joints, they are much less suited (and completely unneeded) in edge joints on solid wood.
    – Graphus
    May 1 '20 at 15:39
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My understanding is a biscuit's primary purpose is to hold the timber perfectly in position as the glue dries which often takes days even with glue that "dries" in minutes.

For example I have a tube of "instant" liquid nails that advertises a strong hold after just 2 seconds but requires a full week to reach it's full strength potential.

Any movement during that week massively reduces the strength of the glue bond. I've even seen joints separate entirely due to expansion/contraction of the timber as it adjusts to the ambient humidity.

A biscuit only needs to be strong enough to hold the timber in position for an hour or a few days after which the glue alone will be strong enough to hold the joint together (dowels or screws or brad nails or clamps or a spline joint would be just as effective, but biscuits can be quicker/easier than any of those).

Many glues are so strong even with a sledge hammer you'll struggle to separate an edge joint. The timber will splinter and snap while the joint holds strong.

These things obviously vary depending on the timber and glue being used as well as surface preparation (sanding/cleaning/etc). If you're worried your joint won't be strong enough, test it out with a scrap piece of timber. If it doesn't work, I suspect you're doing something else wrong (for example some biscuit jointers cut the slot too big the biscuit should need a light taps with a hammer force it into the hole).

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  • Appreciate the details. Do you have any suggestions on wood glue for hardwoods, optimal prep work, grit of sandpaper before gluing?
    – user289394
    May 1 '20 at 4:06
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    Abhi, no glue in common usage in woodworking takes days to cure. About the slowest cure time one would encounter in normal circumstances would be 24 hours.
    – Graphus
    May 1 '20 at 15:41
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    @user289394, any common woodworking adhesive is fine. Pick based on the other characteristics you want (e.g. resistance to moisture, open time) and don't be concerned with strength, since even the weakest glue is strong enough if used correctly. As for the rest of your queries, search the archives here and you'll find all the info you require — I'm not providing a link deliberately since you'll read a lot of useful ancillary stuff if you seek out the info yourself, reading as you go along, rather than just reading the one or two most relevant Answers that I can recall off the top of my head.
    – Graphus
    May 1 '20 at 15:46
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    @user289394 a good quality PVA based “wood glue” is usually the best choice but not always. Read the instructions on the label carefully and do some trials before using an unfamiliar glue. May 2 '20 at 22:36
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    Construction adhesive is not used in woodworking per se. It's used in construction/mounting. The distinction isn't just nitpicking, it's important because it wouldn't normally be used in a joinery situation, which is what was asked about and what your Answer refers to. So like I said,l none of the glues used in that context take days to cure making that point a red herring.
    – Graphus
    May 4 '20 at 9:00
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Side note: while writing this question realized making a two biscuit cuts parallel to each other would do the trick too.

My biscuit joiner came with an alignment plate that snaps over the fence to raise the blade the thickness of the blade kerf, so that you can easily cut double thickness slots for double biscuit joints. If yours didn't, you can accomplish the same thing by planing a piece of wood to the thickness of your machine's kerf, and cut two slots in the same place, once with and once without that shim in place.

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  • The other option is cutting slots from both faces and having two separate slots for the biscuits. I would have never thought to make one slot sized for 2 biscuits. Interesting approach.
    – FreeMan
    Feb 3 at 16:34

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