Biscuits Thickness

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Forum topic by bilyo posted 01-11-2019 03:42 AM 1179 views 0 times favorited 18 replies Add to Favorites Watch
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1167 posts in 1985 days

01-11-2019 03:42 AM

I have a Craftsman biscuit jointer which, except for the handle on top, is identical to the Dewalt. I usually use biscuits for alignment purposes rather that strength. However, the biscuits I have on hand are a bit thin and, as a result, wiggle significantly when inserted into the slot. I know that the biscuits are supposed to swell when exposed to glue, but that doesn’t help much during glue-up and clamping to keep things aligned. Has anyone had experience with this problem? If I buy new biscuits, are there some brands that are consistently better fitting than others. I haven’t tried to “humidify” them to get them to “puff up”. Has anyone tried that? Don’t want to get them too wet.

18 replies so far

View GrantA's profile


2894 posts in 2290 days

#1 posted 01-11-2019 04:23 AM

I like mine about like this

Hehe sorry couldn’t resist. I don’t use wood biscuits much at all but I bet a little moisture (damp rag maybe) will fatten them up. Assuming you’re sure the cutter isn’t at fault – it could have a burr or be bent. The dewalt brand biscuits I recently bought were pretty snug when dry

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1167 posts in 1985 days

#2 posted 01-11-2019 03:55 PM

:>) (laughing quietly with a shake of the head) I was almost expecting that. At least, I wasn’t surprised.
I thought about the cutter after my post. I’ll check it today.

View ScottM's profile


748 posts in 3029 days

#3 posted 01-11-2019 04:21 PM

I notice the same thing with mine. I have a biscuit jointer from HF. I also bought the biscuits at the same time. I then noticed how loose they were. I figured it was a HF thing so I bought another batch from Lowes and have the same problem. My next option will be to try a new blade. Maybe the cheap HF blade on it is too thick…

View pintodeluxe's profile


6210 posts in 3696 days

#4 posted 01-11-2019 06:31 PM

The Dewalt brand biscuits fit a little tighter than other brands. There is even a notable difference between Dewalt and Porter Cable if you can believe it. I don’t think my experience is based on humidity changes, because all were sealed in plastic canisters.

I do think some play is helpful when assembling a project with glue.

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

View LesB's profile


2622 posts in 4326 days

#5 posted 01-11-2019 06:33 PM

“Maybe the cheap HF blade on it is too thick…”

If the blade is too thick and it has carbide tips that are wider than the disk why not grind them down a little. Yes, carbide is hard to grind so you may have to take it to a saw shop that sharpens carbide blades.

I have been using a Porter Cable for 20 years and never had a problem with undersize biscuits. If anything it is the other way around the biscuits which are compressed have expanded slightly in storage from ambient humidity and I has to sand them just a little. So I’m careful to keep the biscuits stored in an air tight container.

-- Les B, Oregon

View HokieKen's profile


15157 posts in 2021 days

#6 posted 01-11-2019 07:36 PM

It’s the biscuits. When I bought a jar of Dewalt biscuits, I noticed some joints were a little sloppy and others were pretty tight. So, I assumed the cuter was cutting inconsistently. Nope. Using calipers I verified that the slots were consistent. The biscuits, on the other hand, varied as much as .015”. Doesn’t sound like a lot but it is. These were all biscuits from the same jar mind you. So, now when I use biscuit joints, I use my caliper and select the exact biscuits I’m going to use before I start assembly.

Regarding the “humidification”, I find glue will swell them so if you use a glue with a long open time, you can coat the biscuits and insert them into one piece and wait a couple minutes before sliding the other piece on. Usually that’s sufficient to allow them to swell up for a tight fit. Never tried wetting them. I’d be afraid it would effect the bonding with the glue.

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

View bilyo's profile


1167 posts in 1985 days

#7 posted 01-11-2019 10:35 PM

I checked my biscuit jointer blade today. It is cutting a slot 4mm (5/32”) wide which is the standard, I believe. I am trying to put a sample of the biscuits in a very humid environment, without directly wetting them, to see if they will puff up. I’ll let you know. In the mean time, I’ll try some of the Dewalt biscuits.

View Kirk650's profile


680 posts in 1631 days

#8 posted 01-12-2019 02:08 AM

Thin biscuits are not my problem. I have a high percentage of swelled biscuits, and would like to find a good way to get them back to the original thinness. I haven’t yet tried the microwave.

View Richard Lee's profile

Richard Lee

309 posts in 1658 days

#9 posted 01-12-2019 02:18 AM

Ive used the original Lamello biscuits for years and never had a problem.

View AlaskaGuy's profile


6111 posts in 3192 days

#10 posted 01-12-2019 05:06 AM

I have just been retrained. Those so call ed biscuits are not biscuits at all. They are actually flat dowels.

-- Alaskan's for Global warming!

View MSquared's profile


1149 posts in 797 days

#11 posted 01-12-2019 05:39 AM

Hmmmm …

-- Marty, Long Island, NY

View splintergroup's profile


4049 posts in 2105 days

#12 posted 01-12-2019 03:50 PM

I always had problems with the biscuits being too thick. I learned to test fit the biscuits before gluing. Fixes are a quick heating in the microwave or a simple whack with a mallet before installing. (these were all PC brand biscuits for my PC 557)

For thin biscuits, I’d use the wet with a damp rag trick. Glueing should not be affected, but they are only for alignment right?

View WoodenDreams's profile


1161 posts in 793 days

#13 posted 01-12-2019 06:48 PM

#00, #10, and #20 biscuits are normally standard to size and thickness. You can always make your own. Take a scrap piece of hardwood, and slice a strip of hardwood to your thickness that your having a issue with, and cut to shape on a bandsaw. Would save you $6.00 on 85 #20 biscuits.

View steve104c's profile


52 posts in 2121 days

#14 posted 01-12-2019 07:16 PM

Was watching a woodworking show on PBS. The so called “professional “woodworker was using biscuits in one of his projects and said that the biscuits were made from plywood. Stopped watching that program. I don’t know everything but I do know when someone is full of IT. The biscuits are made from thin pieces of beech and cut with a cutter like a cookie cutter w/ the size and sometimes the brand pressed into it. If you live in a humid area like I do, you need to keep them in a sealed container. Loose is better than too tight. They will swell when they absorb the glue. Be sure you have enough glue in the slot. Not all biscuit jointers are =. The blades can very in thickness and the different biscuits can also vary. Try leaving biscuits out and see if just the humidity will make them swell just a little. I don’t thank you should put them in water. Then the glue won’t absorb into them properly. Now if you’re using polyurethane glue, yes dampen the biscuits. You definitely would have to clamp and leave clamped for a longer period. Awfully messy too. USE A WATER BASED when gluing up panals( table tops,cabinet sides etc). Steve

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1167 posts in 1985 days

#15 posted 01-15-2019 02:15 AM

Thanks for all the comments. I just wanted everyone to know that I suspended one of the thin biscuits in a jar with about 1/4” of water in the bottom so that it was in a very humid environment (not directly wet). After about 48 hours, the biscuit had puffed up to the standard 4mm (5/32”). Of course, it then fit the slot with no slop.

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