Mitered joint advice

[Guy Dotan]

I am building a ladder desk similar to this: http://www.westelm.com/products/476908/?catalogId=73&sku=476908&bnrid=3902401&cm_ven=Google_PLA&cm_cat=Shopping&cm_pla=Desks&cm_ite=AllProducts&gclid=CjwKEAjw9Zu5BRCS_OuVibujhQ0SJAD7t4KrK9mF3O7W 8rVH5M6W4upTriT7Hxt-0MFFAU9kYZ1yyxoCncDw_wcB&kwid=productads-adid^47300713553-device^c-plaid^61848387786-sku^476908-adType^PLA

My question is about the desk/box, which will be made of 3/4 ply veneered with Zebra wood (paper backed, 10 mil) - I see 2 options:

(1) Veneer all panels, then cut miters and use dominos to align the miter joints
(2) Veneer the internal side of the panels first, then do butt joints, like in the picture. Once assembled, add veneer to the external panels

Tools I have: Festool tracksaw TS55 and a new Ridge Carbide TS2000 40T blade for my Sawstop PCS.

Which option would give me a better edge - 1 or 2? If 1 - should I use the tablesaw or tracksaw?

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[John Blazy]

Veneer your panels first. Then use the tried and true folded miter trick - no need for biscuits or dowels or screws - the glue is stronger. I learned this technique 30 years ago when I worked at a commercial millwork shop, and have been using this trick ever since - done conference table pedestals all the way to common cases with this technique, and I improved on it by using polyurethane glue AND yellow glue.


Look at this diagram - pretty self explanatory. Cut your mitered edges, use strapping / shipping tape on the outside of the three inner joints - tape becomes the hinge. Cannot use any other tape - wont work. I use heavy 3M shipping tape.

Flip over, and run your glue lines, then fold it up, slowly closing the box so as not to starve the joint or pull the tape seal. use spring clamps or binder clips for the final outside joint. I hot melt the glue cleat on, then after total box is dry, I saw it off then scrape the hot melt off to make sure it doesn't tear out the wood grain.

This works on any size rectangular or square cross section in any material that holds tape and glue - Ive done it with plywood, MDF, veneer or not, glass and plastic sheet. This is one of the best shop tricks I ever learned.

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[Guy Dotan]

Thanks. In addition to the glue up question, I wonder what would produce a better cut and, as a result, edge/corners: the saw blade in option 1 or the veneer hand see in option 2.

[John Blazy]

I always use the tablesaw, tilted at 45. Good blades will create a great cut, as long as it doesn't bind and burn a dig in the miter. If you go for option 2, and veneer after glue-up of the mitered box, then that appears like it will work well, but take multiple steps. Do you plan to glue the veneer with wood glue or contact cement? Contact cement, although easier, will telegraph its lumpy texture right through the veneer and make your finish look ugly. I personally would veneer the panels first. Pre-cut to smallest size with added size for trimming, glue and clamp the whole stack, then saw to final size, then tape wrap miter trick.

[Guy Dotan]

I plan to use Titebond II, iron-on method.

[Robert Engel]

I would also veneer first and assemble with miter & spline. Veneer edges last.
When cutting the miters score the veneer first to avoid tear out.
Then use a shooting board to find tune(be sure you have a backer board to avoid tearing out far side).

Personally I would cut the widths oversize and cut to final length/joint after cutting the miters. A nasty tear out can ruin a piece.

[Jamie Buxton]

The challenge with doing long mitered joints like that with veneered plywood is that there is no room for error. The joints have be precise to an accuracy well under the thickness of the veneer -- that is, only a few thousandths of an inch in your case. If you miss, there's no way to recover; you can't sand it out because you'll go through the veneer. Another issue with mitered joints in plywood is that the edge must be a knife edge. You can't soften the edge for fear of going through the veneer. And a third issue is that if the corner gets dinged in service, it will go through the veneer.

You'll notice that the West Elm piece doesn't use mitered corners -- probably for all those practical reasons.

If you make the piece from solid lumber, you can use miters at the corners without fear.

[Mike Ontko]

I completed a bookcase project earlier this year using home made veneers (CVG Doug fir) glued on to birch ply with contact cement and the mitered corners you're considering. The pictures aren't the best (taken with my LG Nexus 5), but you can take a look at the results here: Bookcase - IKEA Valje copy (http://www.sawmillcreek.org/album.php?albumid=865).

I used biscuits to align and join the mitered corners, but don't know that I would recommend it for others, especially if the plywood that you're working with has any voids along the mitered faces. I also used Titebond III, which did provide a little more open time for getting things aligned and clamped up. With the size of your project, you may not need to use any reinforcement but some kind of additional internal support (splines or keys?) might be a good idea depending on the amount of pressure or abuse you think the desk will receive over time.

Also, as mentioned above--do the veneering first, then cut and miter your pieces.

[J.R. Rutter]

Add my vote to the veneer and miter fold camp. I don't even spline. A sharp blade and decently aligned saw work well. I burnish the edges slightly rather than hitting them with any sandpaper.

[Guy Dotan]

The challenge with doing long mitered joints like that with veneered plywood is that there is no room for error. The joints have be precise to an accuracy well under the thickness of the veneer -- that is, only a few thousandths of an inch in your case. If you miss, there's no way to recover; you can't sand it out because you'll go through the veneer. Another issue with mitered joints in plywood is that the edge must be a knife edge. You can't soften the edge for fear of going through the veneer. And a third issue is that if the corner gets dinged in service, it will go through the veneer.

You'll notice that the West Elm piece doesn't use mitered corners -- probably for all those practical reasons.

If you make the piece from solid lumber, you can use miters at the corners without fear.

A lot of votes for the mitered joints, but Jaime is making a good point... And - with option 2: assembling first, then applying the veneer and running a veneer saw along the panel of the assembled box, I should get a pretty good edge... (At a minimum, I'd avoid angle accuracy and alignment assembly problems.) Still debating...

[John Blazy]

Ahhh, JR has seen the light. Once you try the folded tape miter trick, you will never go back to any other method. It creates PERFECT closed joint miters, when done right, and with polyurethane construction adhesive, (I use yellow glue in the toe of the miter, and PL poly in the heel) its stronger than any other fastening method.


And JR is on to something as well about burnishing the sharp toe of the miter. If you very lightly sand an arris on the sharp edge of the miter, the joint folds tighter. I have sanded too much before and couldn't fold totally, so I do only a slight arris, if any. And also need to let the glue sit for a few minutes to soak into the ply or MDF core a bit before folding, so as not to starve the joint.

You can do what you want, of coarse, but remember that most posts are from hobbyists. I am a professional with 30 years of ultra high end fine furniture building experience FOR MONEY, so the time taken to spline and clamp each joint is losing $. I have done this tape wrap miter trick probably a hundred times. I still love furniture building and woodworking BTW.

[John Blazy]

If you make the piece from solid lumber, you can use miters at the corners without fear.

Good point. I have used the tape wrap trick on solid wood as well. best of both worlds. But the OP is using veneer, specifically.

BTW - interesting idea, Guy, of iron on with pre-applied Titebond. I have always heard of this method, but never tried it. Let us know how well it works.

In all honesty, veneering this small of a pc after butt joint glue-up, really is a viable method. The tape-wrap trick comes from the standpoint of pre-veneered panels, when you aren't applying veneer later.

[Guy Dotan]

Thanks all. I recently tried the Titebond II iron on in small scale (practice piece) and it worked really well.