Best way to cut wedges for wedged tenons

[Bob]

I must have read a jillion articles on Mortise and Tenon Joints in the last few weeks and I'm having pretty good success making floating tenon joints with a router, table saw and hand planes for touch up. Now I need to emulate some wedged tenon joints.

In all the articles I've read, they show clear pictures of suggested dimensions, ratios, angles etc. Lots of attention is paid to techniques for cutting mortises and tenons. But everyone seems to gloss over techniques for cutting these little wedges.

Now to describe my challenge.

I'm building a plywood rack which will have a base composed of 23 1" oak dowels with PVC sleeves around them to act as little rollers. These dowels will be mounted between two 2x6 rails. I've decided the best way to mount them is to emulate a wedged tenon - cut a slot in each end of each dowel and drive a wedge into it. Any commentary or suggestions on how to make the wedges are welcome. I have a tablesaw, drill press, several hand planes, a Japanese saw, and some chisels in my arsenal.

I know some of you will say "glue it like it is, that ought to hold just fine". The problem is the logistics of such a glue-up. Each dowel will have

15 little sleeves on it. In order to just glue the ends in place, I'd have to do it all at once - fitting 374 parts, 54 joints and trying to square an 8 foot by 2 foot assembly before the glue sets. No Way! I put the main frame together, squared and glued it without a hassle. Now I've got to install the dowels/sleeves doing it patiently one at a time.

I am chronicling my progress on a web page. I've got it through dry fit-up and begun some gluing. Perhaps this will help you see what I'm trying to do.

Davis Houston, Texas

[bridger]

I'd say you have the perect excuse to get a band saw....

[max]

It's easy. Tilt the miter gauge on your table saw. Dimension your stock for width and length. For example, a 1 inch thick board, 3/4 inch wide and a couple of feet long. Set the miter gauge to an angle such as 3 or 4 degrees (87 degrees). I am not in the shop so you need to experiment. Make the first cut and then flip the board and take another thin cut. You now have a wedge. You will need to flip the board for each cut. You will also need to make a stop so you get the same thickness wedge each time. I knock these things out so fast it is scary. I can cut 20 or so a minute. max

[Bob]

Bless you! I get it and I can do it. I'll give it a whirl tomorrow.

Bob

[gandalf]

-------------- Why do you have to do it all in one go? Why not just glue the dowels in one rail, ignore the sleeves for now, and dry fit the other rail. Let dry, remove dry fit rail , slip on the sleeves and then glue the remaining rail in position.

Also a thought regarding using wedges, if you don't flair the joint you won't get any mechanical benefit - all you'll get is a tight friction fit, which will likely fall apart when all the heavy sheets goods move.

[Juergen Hannappel]

[...]

I make my wedges usually from beech firewood stock using a hatchet, it gives due to the optimal grain orientation achieved by that method the most stable wedges. It takes a bit of experimenting until the wedges look like you want them, but it's quick when learned.

[George]

Cedar shakes.

Other than that, as advertised, long slow slopes to prevent rejection.

[John Girouard]

What worked well for me recently was to start by getting the stock down to thickness and width, but leaving it long (1/8" x 1/2" x 24" in my case). I then took the wedges-to-be over to the disc sander, sanded the tip of my 'stick' into a wedge shape, and then cut the wedge off the stick with a hand saw. Repeat as often as necessary.

-John

[Andy Dingley]

How are you going to drive in a cross-grain wedge in such a soft timber as cedar ?

[Liam]

I made a jig to make wedges. Basically it is a hole that accepts the wedge horizontally. I cut wedge blank on the bandsaw about a 16th of a inch away from the line and place it in the hole. Then I plane the rough side smooth and touch it up on the disc sander if I need to.

[Larry Jaques]

On Tue, 09 Nov 2004 04:21:48 GMT, "Bob" calmly ranted:

I'll tell you right now what I found out in building a sheet goods rack. They're MEGA top-heavy and will want to split the uprights apart with any movement. My first assembly attempt pulled the 3" lags out of the cement with the weight supported by a 4' pole. I then resunk them and mounted a 9' 3/4" pipe through the ceiling. That did it. With yours on wheels, you'll have to keep it to 2' tall sheets, MAX. Goto

to see the original product, before the tall pole. I got it half loaded and it fell right over. That was a humbling learning experience. ;)

Use the Japanese saw to slice a 3/4" length of wood, rip it to just under 1" width, then use the saw to cut the wedges with the grain vertical. Five degrees is a good angle.

Swab an inch of the ends and glue them in while assembling them individually. The wedges are glued in, too. Tap them in with a mallet. A bit of wax on the end keeps glue from sticking.

Again, I caution you to mount it to something on one end and let it pivot from there. With those side-loading problems, they're just too top-heavy for a mobile unit--unless you make it an A-frame and balance the side loads.

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[jo4hn]

[snip]

These probably should be cut with the grain rather than across it. Crosscut something like a tubasix to the proper length and then follow the instructions above, you should have it. If these are to come out of hardwood, you will have to make a jig to hold the piece. mahalo, jo4hn

[George]

[Bob]

Well, gandalf, my inexperience shows. Your answer is what I should have done. I was focused on getting the whole contraption square and viewing the base as the most important part to square up to be sure the rollers aligned with each other. So I got that job done (four 2x4 cross braces with M&T joints) and then realized I was challenged with how to handle the dowels. I thought I had all this figured out, then realized putting the sleeves on would eliminate all the flexibility of setting the dowels.

I was thinking of drilling pilot holes above and below the dowel holes and dumping glue in those holes, spinning the dowels to spread the glue, then inserting the wedges.

I'm real close to a big screw up and any further advice is appreciated.

Bob

[Daniel Grieves]

Could you drill a little hole in the end, cut 2 thin kerfs and then wedge in a round pin? Something shaped like a golf tee with the top cut off?

[Bob]

I greatly respect your advice, Larry. I had that input from another user earlier. I do not view this design as final product. I originally intended to have a fixed rack, then realized I could put wheels on it to allow me to move it away from the wall a bit if needed for loading and unloading.

I have considered adding fold-out "struts" with additional wheels to provide stability and may do that after I get it finished. I could also just take the wheels off and not use them.

I have some questions about your rack. I don't see any corner or side casters on it. Is that true? Its seems like it would have a very high propensity to turn over, if that's the case. What is built into the design to resist turning over?

Bob

[Larry Jaques]

On Wed, 10 Nov 2004 00:44:57 GMT, "Bob" calmly ranted:

The struts would be better. And if you're keeping it mobile and not affixing it to something solid, fixed struts would be better. Half a dozen sheets/part sheets of ply and MDF can cause a whole lot of damage if they knock you into something solid or sharp and spinny, knowwhatImean,Vern?

I have the single 4" caster on one end and the other is attached to the pipe which goes through the ceiling. The pipe supports it. I have probably 400 lbs of lumber on it right now so the side loading is at least 200 lbs. when it moves around. That relates to probably a ton on the bolts (which is why the short pipe didn't work with half that weight on it.)

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[Bob]

Its been years since I took an engineering mechanics class, but I remember a few basics. Assuming you have a two foot wide cart, a 200 lb force on the side of the cart would equate to 4800 lb force at 1/2 inch from the center line of the cart. In terms of support you would substantially increase the strength of the system and resistance to turning over by putting casters on the sides or corners instead of the center. That's why I mounted wheels on the side of my cart-in-construction.

The other factor is whether the sheetgood gets a chance at tilting any at all. One finger can keep a 3/4' MDF sheet from falling over, if its perfectly vertical. But try that when its at a 60 degree angle. I'm guessing at the dimensions of your cart, but it looks like its pretty easy for a sheet to slide and reach a 60 degree angle. This is not really "top heavy". Its what I would call "catastrophic shift in turning moment".

Well enough techno-babble. There's still your "knowwhatimeanvern" factor.

I plan to finish the cart, then put a couple of sheets of plywood in it and shake and wiggle it around to see how prone it is to falling over. I'll probably end up putting the struts on it.

Bob

[Larry Jaques]

On Thu, 11 Nov 2004 05:40:26 GMT, "Bob" calmly ranted:

The inside width is 7-1/4", height 35-1/4", you figure the angle. I'd guess it would never get even CLOSE to 60 degrees.

I'd bet money on it. ;)

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[Bob]

You are right. Its 78 degrees.

I'm not giving odds, because I think you are right. About 2 weeks ago, I decided to go forward with my design because it was dictated by space limitations. It originally was going against the wall and would never budge. The casters came as an afterthought, followed by the idea that I'll have to do something about them if I think they are going to kill me.

I will however buy you a cup of coffer or a beer whenever we're in the same neighborhood. I appreciate being able to have a civil discussion without the potential mudslinging that could occur.

Best regards, Bob Davis Houston, Texas