Loose M&T Joint Question

[Mike Goetzke]

About a year ago I made an impulse buy on a Delta M&T machine. I'm half way through a futon project based on plans I got at Rockler. The end frames have a rail/style construction that calls for dowels. I was thinking of using a M&T joint, but, I thought of it too late. I cut the rails to size per the plans. I should have left them oversize so I could have cut the tenons on them.

I was thinking of using loose tenons that I hear talked about once in a while here. Looking at my M&T machine I take it that you have to use a router or some other tool to mill the mortise into the end of the long rails?

Help/suggestions appreciated.


Thanks,

Mike

[Paul Girouard]

You rout out a mortise on all connecting pieces , the tenon is a separate piece of wood , think of it as a big biscuit.


http://www.workbenchmagazine.com/main/images/wb282-tenon02.jpg

Snagged from :

http://www.workbenchmagazine.com/main/wb282-skillbld01.html

Or this :

http://www.workbenchmagazine.com/main/wb282-skillbld01.htm

[Mike Goetzke]

That's sort of what I thougth - guess the M&T machine is still a paper weight for now.

[Joe Chritz]

Very tall bench. I am not familiar with that model but some can swing or have the table move out of the way to allow you to do tall boards.

You could also use a router with a very simple jig and square the corners on the long pieces. Then use the mortiser on the others.

Joe

[Frank Martin]

I would say build a very simple router jig and use your plunge router to cut mortises. Then make your tenon blank with rounded sides and cut to lenght.

[Peter Quinn]

I use a plunge router with a spiral carbide up cut bit and a template guide bushing in conjunction with a simple mdf jig made on the router table. I make a 3/4" slot in a piece of 1/4" MDF. The length of the slot equals the width of the tenon plus twice the off set of the guide bushing. I screw through the face of the template into a edge of square piece of 3/4"X4"X6" hardwood which acts as a clamping point and a fence. I layout a mortise on the thickest work piece, for example the leg on a leg and apron assembly. Clamp the template to the work piece, clamp the hardwood fence to the opposing face and assemble the jig. In cases where an apron joins a leg with a set back I prepare a shim to slip between the fence and work piece for the thinner parts equal to the required set back.


I use a 3/4"OD brass bushing for 1/2" or 3/8" mortises. Remember to center the base plate carefully with a centering pin. With the jig securely clamped to the work piece plunge a hole at each end of the mortise, then go back and take light passes (1/4" max) to clear out the stock between these holes.

Always reference the jig from the outward face of each work piece to nullify any centering issues. Similar results can be achieved through careful use of and edge guide if one is available, though a jig to balance the routers base or a square vise on a joiners bench will be necessary for most work pieces.

It actually took me more time to write this post than it typically takes to set up my router and make a pair of mortises. Additionally you will need to accurately mill loose tenon stock, rip it to width, rip shallow channels in the faces to relieve hydraulic pressure once glue is applied, and round over the edges using four passes with a radius equal to half the tennon's thickness.

Really less confusing than it sounds.

[Bruce Benjamin]

Mike, this is an excellent application for your EZ Smart and SRK. If you're going to be using a router to make the mortises why not set it up like Dino does and make it EZ. You'll have to get a little creative to make the mortise on the end of a long rail but it certainly can be done. Post this over on the EZ Forum and I'll bet you'll get some good advice. I don't remember which EZ tools you have but if you have the SRK you're set.

For those not familiar with EZ Smart and the SRK, the SRK is an acronym for Smart Router Kit. It holds your router so it can slide along the guide rail. There are limit stops for left and right and in and out so it ends up working like a manual CNC. Mortise and tenon joints are pretty simple with a simple jig to hold the workpiece on the edge of the table. Here's what the SRK looks like. http://www.eurekazone.com/products/detail/srs.html Here's an example of how to make a M&T jig for your SRK.
http://eurekazone.com/gallery/How-to-make-a-mortise-and-tenon-system Here's some more pics showing what the Limit Stops can do. http://eurekazone.com/gallery/EZ-Mortise-tenons-with-limit-stops

Bruce

[Chris Padilla]

Domino? :D Dowelmax? :D

[Vince Shriver]

How about a simple self-centering doweling jig like the "dowel it". $40 + s & tax. Of course, the Dowelmax would be the berries, but not necessary for this project.

[Chris Padilla]

For floating tenon and mortise joinery, what are the guidelines for the size of the mortise and tenon?

For example, I have a 5.25" wide board that is 1.3" thick and I'm not sure what size to make the floating tenons and mortise. This is for my gate project that will have 2 stiles and 3 rails made of western red cedar.

[Mike SoRelle]

For floating tenon and mortise joinery, what are the guidelines for the size of the mortise and tenon?

For example, I have a 5.25" wide board that is 1.3" thick and I'm not sure what size to make the floating tenons and mortise. This is for my gate project that will have 2 stiles and 3 rails made of western red cedar.

I'd always heard the rule of thumb of the thickness of the tenons should be around 1/3 the overall thickness of the board, but I've never heard any hard and fast rules on length.

At some point your huge strong tenon is undermined by the thinned walls of the mortise to accept it.

I'd assume there's no real difference in this for a loose/floating tenon vs an intregal tenon since when it's all said and done, they serve the same purpose.

Mike

[richard poitras]

Or you could try a mortis-pal...