Embossing floating tenons like a biscuit?

[Phil Thien]

So my little mortising jig (http://www.cgallery.com/jpthien/mj.htm) gets quite a bit of use. I'm even contemplating making another version that I can use with Dominos because making my own tenons can be a pain in the rear. For example, a tool stand like my little double bandsaw stand would require 64 tenons, about 96" of tenon stock. After a while, you feel like you're making tenons instead of furniture.

In the meantime, though, I wonder whether anyone has ever considered embossing floating tenons? One of the issues I have is that I cut the tenons to a nice friction fit for my mortises. They're snug during a dry fit. If I don't work fast enough at seating the tenons in the mortises once I'm using glue, they can get stuck and I can need a considerable amount of clamping pressure to move them. And my clamps aren't that great. It always works out, but can be a little nerve wracking.

Now, I could simply sand them down so they aren't that tight, but my concern would be that my joints wouldn't be that strong.

I have, on occasion, use the serrated jaws of pliers to squeeze the tenons. This both compresses them and installs a pattern that probably helps distribute the glue. But this (use of pliers) is time consuming. I don't mind it when I only have a few tenons to do, but...

So I was wondering if there is any sort of cross-hatching or embossing stamp I could buy and just strike the tenons with the stamp/hammer. I'm thinking this would compress them slightly, and also add a good glue distribution pattern. Maybe a stamp that is 1" square or so? That would only require four strikes per tenon.

Or maybe some sort of embosser with a pliers with some sort of compound action, maybe with a 1/2" or 1" square pattern?

Is there anything like that out there? It would be handy. I've tried searching McMaster, don't come up with much. Googling embossers is a good way to find tools for embossing paper.

Oh BTW, I've previously used the jaws of a metal vise. The backlash in the screw can make it time consuming and difficult to get a consistent amount of pressure. So that wasn't a good method for me.

[Fred Maiman]

I see you route the slots wide for some fudge factor. But how did you keep the 2x2 pattern on that board with the offset from the edge (your middle board) where the slots aren't centered on the board so the slots are all alignment. There isn't much margin for error there is there?

[david brum]

Phil, it might be easier to try slower setting, thinner glues. I've been using diluted Titebond for floating tenons. Word is that you can dilute it 5% and get 50% more open time. I use regular, old Original Titebond for this. It makes the glue a bit runnier and it doesn't seem to grab the tenons as quickly. It is much less stressful during assembly. Seems plenty strong after drying. I get around 15 minutes open time in my somewhat humid shop. I imagine you could do the same thing with fancier glues, like Extend and get more than 30 minutes.

[Phil Thien]

David, I'm using the white Glue-All now. The open times are probably comparable to wood glues w/ extended open times.

I still think I'd like to try something to compress the tenons. At least I'd like to try experimenting with it.

[Phil Thien]

I see you route the slots wide for some fudge factor. But how did you keep the 2x2 pattern on that board with the offset from the edge (your middle board) where the slots aren't centered on the board so the slots are all alignment. There isn't much margin for error there is there?

Oh, that is easy. It is actually easier to do, than to explain.

Here is the process:

First, I route the stretchers with the mortises in the end-grain (the left board with the tenons sticking out). I mark the centers of the mortises, and I route two mortises with one face of the stretcher against the fence of my jig, then flip the workpiece around so the other face is against the fence of the jig and route the other two mortises. Flip the stretcher end over end and do four more mortises.

Now I simply place one tenon in my stretcher and use that to set the jig. So if I want a 1/4" offset (like that middle board), I use a scrap of 1/4" hardboard against the fence of my jig, then the stretcher with one tenon sticking out of a mortise and into the hole in my jig. Once I have the jig lined up, I tighten the screws on the jig, and route two mortises.

Finally, I move the tenon over to the next slot on the stretcher (or just flip the faces of the stretcher if they're equidistant like in this case) and again stick the tenon through the jig and tighten the screws. Now I can route the next two mortises.

Make sense?

In practice it goes very fast.

Nobody ask me how to tell them to make a peanut butter and jelly sandwich.

[Thomas Hotchkin]

Phil
I put all my floating tenons in the kitchen oven at 120 degrees for 20 minutes, before any glue up. They install much easier this way and glue swells them back to original size. Tom

[Alan Schwabacher]

If you use epoxy, the tenons won't swell and the glue won't grab: you can get an epoxy with whatever open time you want. If baking tenons makes white glue work, that's probably cheaper. But I have had good results with epoxy and floating tenons for canoe seats.

[Jeff Duncan]

I make my own tenons and it's a pretty quick and easy process for the most part, depending on how your equipped.

I use up whatever scrap is remaining from the initial milling on the project for the tenons. I bandsaw to rough thickness first and then a pass through the planer to clean up. Next they get ripped to width through the table saw and then run through the router table by hand to round the edges. I then run through the widebelt to dial in the exact thickness, but you could do this with the planer too. I tilt my tablesaw to 45 and run one or two shallow grooves down the lengths of the stock to allow extra glue to escape. Lastly I set up a stop block and cut them to length.

Using this process I can churn out several hundred in an hour or so of shop time. They fit snug, but not so snug that you would have any trouble inserting them....especially once they have glue on them! If your making them so tight you can't get them in....they're too tight. You don't need to add another step, you just need them to fit better. And as for strength I use tenons mostly for modern style interior doors that have very narrow rails so strength of joint is incredibly important! If my joints weren't strong enough, the doors would come apart much quicker than a traditional style door!

good luck,
JeffD

[Rick Potter]

Phil,

I cannot remember where, but about a year ago I saw a machine made for sizing biscuits. It worked like a wringer, and you would run the biscuits through it to make them all the same size, eliminating differences in moisture content. Perhaps you could find it ( I couldn't ), and adapt something like that to your needs.

I picture some old planer rollers, the type with grooves in them, fitted to an adjustable frame, and a crank handle. Yeah, I know. I am a Rube Goldberg fan.

Or, picture a waffle iron. Now build something hinged like that for various thicknesses, with a long handle for leverage. OK, Ok, I will quit now:o.

Rick Potter

[mreza Salav]

I have used a similar mortising jig. As for tenons one easy option (instead of building) is to get these from LV:
http://www.leevalley.com/en/wood/page.aspx?p=44779&cat=1,250,43217
They come in different (standard) thickness and long lengths that you can cut to length (and rip narrower if you need).

You can put your tenons in the microwave a bit to get the moisture out. It will absorb moisture from the glue and swell once you use it (just like biscuits).

[glenn bradley]

I see no wisdom in making the surfaces non-smooth. Everything I've ever read about PVA glues recommend a smooth surface. Adding irregularity for grip is fine for epoxies and structural adhesives. I just size my floating tenons the same way I would fixed tenons and treat them the same during glue up; they're just double-ended :D. If you are having trouble with "hydraulic-lock", run your tenon stock over a v-bit in the router table or the over the tablesaw with the blade at a 45* angle to put a couple grooves down each side. That way the bulk of your surface is smooth for a good bond and you avoid the lock problem . . . or just swap it for a squeeze-out problem ;).

From Franklin's site:

Care should be taken to ensure a tight fit between wood pieces with no saw
marks and no burnishing of the surfaces to be glued.

[Bob Wingard]

I think I would simply strive for a SLIGHTLY less snug fit ... it would be a whole lot simpler.

[John TenEyck]

Yes, exactly like this. Make the tenons fit correctly and you have no need for extra steps that also may result in lower joint strength.

John

[Phil Thien]

Yes, exactly like this. Make the tenons fit correctly and you have no need for extra steps that also may result in lower joint strength.

John

Actually, the reason biscuits are compressed, and Dominos are embossed (with glue channels) is that it results in STRONGER joints.

[John TenEyck]

Actually, the reason biscuits are compressed, and Dominos are embossed (with glue channels) is that it results in STRONGER joints.

I doubt it. Biscuits don't really add much, if any, strength to a cured joint. They are used primarily for alignment. The swelling that happens when the glue is applied helps in holding the joint in alignment and secure while the glue dries. Whether it adds any additional strength the glue has dried is questionable. Dominos have glue channels so that glue doesn't become trapped in the joint, just like dowels do. I make my loose tenons the same way. Everything I've read about joint strength says that smooth, clean, close mating surfaces is best. My two cents.

John

[Bob Wingard]

Actually, the best glue joint is between two perfectly flat, smooth surfaces which have been cut ... not sanded... sanding packs sawdust into the pores, inhibiting the glue from penetrating. If you use tenons that are embossed, you are assuming they completely expand when wetted with glue until such contact is attained, which is nearly impossible. By nature, embossing is a crushing process, which fractures lots of the wood fibers, making them weaker. Personally, I would much rather spend the time honing my skills at making a properly fitted joint than to play "crush & pray". If you really want to do the embossing thing, and do it properly, get ready to spend some major $$$ on a press and some custom machined die plates.

[Phil Thien]

Actually, the best glue joint is between two perfectly flat, smooth surfaces which have been cut ... not sanded... sanding packs sawdust into the pores, inhibiting the glue from penetrating.

But you are missing two vital components: Adequate glue coverage, and clamping pressure.

Really snug tenons are more likely to scrape the glue off the mortise and tenon sides as they are assembled, leading to possible inadequate glue coverage.

Not-so-snug tenons aren't close enough to the mortise walls for a good glue joint.

That is why biscuits and Dominos are textured as they are. Biscuits are compressed, Dominos (I think) are embossed. Biscuits can be soaked with glue and expand (and they do expand, as anyone that has too-soon sanded a table top will tell you), and glue in the channels on a Domino will constanty re-wet the tenon as it scrapes across the mortise walls.

[Bob Wingard]

If your joints are so tight that they scrape every last molecule of glue from the surfaces ... which is virtually impossible ... your joints are WAY too tight !!!

Try coating a few biscuits with glue ... clamp them between pieces of wood with waxed paper between them and the wood ... let them sit for a day or so, and open up the sandwich. The biscuits will NEVER fully swell back to a smooth, flat surface ... same with embossed tenons of any type ... once the fibers are crushed, you've lost intimate contact with the surfaces ... and THAT is really what is necessary for a good glue joint. Some of the old time craftsmen used to simply apply a little glue to both surfaces of an edge to edge joint and rub them together, squeezing with only hand pressure ... then letting the joint cure ... but the joint had to be properly prepared in order to do so ... and properly prepared meant jointed flat & smooth.

If embossing or crushing home made tenons had any real merit, I'm sure someone would have marketed a "system" to accomplish such a task ...

[Phil Thien]

If your joints are so tight that they scrape every last molecule of glue from the surfaces ... which is virtually impossible ... your joints are WAY too tight !!!

Try coating a few biscuits with glue ... clamp them between pieces of wood with waxed paper between them and the wood ... let them sit for a day or so, and open up the sandwich. The biscuits will NEVER fully swell back to a smooth, flat surface ... same with embossed tenons of any type ... once the fibers are crushed, you've lost intimate contact with the surfaces ... and THAT is really what is necessary for a good glue joint. Some of the old time craftsmen used to simply apply a little glue to both surfaces of an edge to edge joint and rub them together, squeezing with only hand pressure ... then letting the joint cure ... but the joint had to be properly prepared in order to do so ... and properly prepared meant jointed flat & smooth.

If embossing or crushing home made tenons had any real merit, I'm sure someone would have marketed a "system" to accomplish such a task ...

Interesting. If the compressing of biscuits and embossing of Dominos makes for weaker joints, then why do they perform those steps?

[Bob Wingard]

Compromise between satisfactory ease of use and suitability for the intended task. Both biscuits and dominoes COULD be made more precise ... BUT ... they would be much more difficult to use, and most customers would soon bail out on them. It's all about marketing and perception.

[Fred Maiman]

Compromise between satisfactory ease of use and suitability for the intended task. Both biscuits and dominoes COULD be made more precise ... BUT ... they would be much more difficult to use, and most customers would soon bail out on them. It's all about marketing and perception.

I think you just fell into his trap, Bob. He already has "precise" and "much more difficult to use." He is shooting for "satisfactory ease of use and suitability for the intended task."

[Bob Wingard]

I think you just fell into his trap, Bob. He already has "precise" and "much more difficult to use." He is shooting for "satisfactory ease of use and suitability for the intended task."


I'd have to say you are absolutely correct, sir ... and, with that ... I GIVE UP !!!!