corner clamping

[HowardH]

I have a fairly simple commission to build a pair of floating night tables for my brother and SIL. The boxes are going to be about 15" deep, 20-24" wide and 8-10" tall and I'll use a French cleat to attach them to the wall. My plan is use a glue up of hardwood to make panels and then miter the corners. I could also use a hardwood ply and edge band the exposed edge in the front. I have a Mafell DDF-40 to dowel the corners for strength. My question is what options are there to adequately clamp the miters so once glued, they will be tight. I have a pair of band clamps that I tested on a small box I made as a test piece.

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They don't have enough clamping pressure. I supposed I could use a bunch of parallel clamps and alternate the direction to have clamping pressure on all four sides.  The corner clamps available I have seen are more for holding the parts together in order to fasten them, not to provide clamping pressure to bring in the corners tight.  Ideas?

 

[tallgrass]

You can use tape. Lay pieces flat with no gap on top of tape, then roll. There are a number videos on youtube buy the major woodworking guys. It works great.

one example.

 

[HowardH]

I'd seen that before but had forgotten about it. I'll need to test it out with the dowels or change strategy and use the splines.   

 

[Crazyraceguy]

The first thing I would do in this situation is look into the calibration of the saw itself. Since the outside is the most visible corner in this situation, you need to be sure that the points touch there first, ever so slightly, and with little pressure.
From the pic, I would say that you are not fully at 45 degrees. With one corner, not so bad, but as the error compounds going around the box, it becomes visible.
If you will never really see the inside of the completed box, you can get away with over-cutting the angle slightly, to ensure the outside hits first. It all depends upon how precisely you can get it adjusted, so you don't have a gap on the inside.
As it is now, that's not going to close without crushing something.

 

[waho6o9]

How about some rubber bands?

 

[HowardH]

The first thing I would do in this situation is look into the calibration of the saw itself. Since the outside is the most visible corner in this situation, you need to be sure that the points touch there first, ever so slightly, and with little pressure.
From the pic, I would say that you are not fully at 45 degrees. With one corner, not so bad, but as the error compounds going around the box, it becomes visible.
If you will never really see the inside of the completed box, you can get away with over-cutting the angle slightly, to ensure the outside hits first. It all depends upon how precisely you can get it adjusted, so you don't have a gap on the inside.
As it is now, that's not going to close without crushing something.

I'll need to test some other pieces to get the angle correct.  Thinking maybe a tenth of a degree or two.  45.1/45.2.  The other issue is how much that would throw off the dowel holes, if any. 

 

[guybo]

hi, for ply I would use tape for hardwood I think I would use the offcuts w/ca glue as clamping blocks.Is it like a floating shelf?

 

[HowardH]

hi, for ply I would use tape for hardwood I think I would use the offcuts w/ca glue as clamping blocks.Is it like a floating shelf?

yes.  double sided tape might work for the clamping blocks as well. 

 

[ChuckM]

If I am not mistaken, tape won't work the way tape works on a small box as the dowels may get in the way. If the bevels are dead-on, tape alone will do after the sides are assembled and glued.

Even with re-calibration, there's still a risk of the bevels not coming out dead-on because of the bevels are long in your case. Assuming you are not planning to recut the whole thing, I'd fix the gap(s) especially if it's a painted piece.

Renowned furniture maker Tage Frid used the screwdriver's shank to carefully compress the gap (practise it first on ply if you wanted to try). But I'd clamp everything as close as they can get, and use Timbermate, which doesn't shrink and stays relatively hard after it cures. 

 

[HowardH]

If I am not mistaken, tape won't work the way tape works on a small box as the dowels may get in the way. If the bevels are dead-on, tape alone will do after the sides are assembled and glued.

Even with re-calibration, there's still a risk of the bevels not coming out dead-on because of the bevels are long on your case. Assuming you are not planning to recut the whole thing, I'd fix the gap(s) especially if it's a painted piece.

Renowned furniture maker Tage Frid used the screwdriver's shank to carefully compress the gap (practise it first on ply if you wanted to try). But I'd clamp everything as close as they can get, and use Timbermate, which doesn't shrink and stays relatively hard after it cures.

I use Timbermate a lot.  Do your best and caulk the rest! 

 

[ChuckM]

Correction: Frid did not use a screwdriver (some others do); he used a hammer.

 

[ChuckM]

I use Timbermate a lot.  Do your best and caulk the rest!

I like that slogan. [big grin]

 

[Birdhunter]

I much prefer splines over dowels or Dominos for this joint. I do like the idea of cutting the joints slightly over 45 degrees. I use clear packing tape as a clamp. Works great. I peel off the tape slowly and at an angle so as to not peel off wood fibers. Done a bunch of these joints this way. No drama.

 

[afish]

In cnc world its called miter folding. The bit most sell and use is a 91 degree.  I have done several projects and never needed dowels or dominos. There is a lot of variables but they may not be needed. Or can some be installed after its assembled, from a direction they wont be seen? not sure how the open ends will be addressed but if you can work a panel or block in the middle to prevent racking the dowels are probably over kill.

 

[Rob Z]

Hello Howard

Many years ago I built a table that set on an octagonal pedestal.  I wasn't sure how I would clamp the pieces for the base and a friend who helped me pulled out some shims, sticks and ~ 1/2" thick rope. (I recall thinking "Uhhh what are you gonna do with that stuff? [huh] " )  We wrapped several lengths of rope around the pieces once they were glued and cinched the rope  as tightly as possible. We  then inserted shims between the wood and the rope to take up any small amount of slack. In some places we  put the small stick under the rope, rotated the stick, and that really tightened things up.  Since then, I have used this technique many times to tighten up and clamps stuff that was other wise difficult to fit with clamps.

The same approach might work for your project, although you might need some folded pieces of cardboard on the corners so the rope doesn't damage that knife edge along the bevel of the plywood.

 

[Michael Kellough]

Lock miter router bit solves all the problems in this project.

 

[Dr. P. Venkman]

Lock miter router bit solves all the problems in this project.

This is what I was thinking. With a joint that long, you can use the lock miter and put several clamps across it - it should pull tight and stay square.

It’s a really strong joint, too.

 

[Stone Message]

If I am not mistaken, tape won't work the way tape works on a small box as the dowels may get in the way. If the bevels are dead-on, tape alone will do after the sides are assembled and glued.

Even with re-calibration, there's still a risk of the bevels not coming out dead-on because of the bevels are long in your case. Assuming you are not planning to recut the whole thing, I'd fix the gap(s) especially if it's a painted piece.

Renowned furniture maker Tage Frid used the screwdriver's shank to carefully compress the gap (practise it first on ply if you wanted to try). But I'd clamp everything as close as they can get, and use Timbermate, which doesn't shrink and stays relatively hard after it cures.

Glue alone is all you need for this project. I use tape and glue for drawers, boxes and all sorts and never need dowels, dominoes or biscuits (except with my tea).


Peter

 

[HowardH]

If I am not mistaken, tape won't work the way tape works on a small box as the dowels may get in the way. If the bevels are dead-on, tape alone will do after the sides are assembled and glued.

Even with re-calibration, there's still a risk of the bevels not coming out dead-on because of the bevels are long in your case. Assuming you are not planning to recut the whole thing, I'd fix the gap(s) especially if it's a painted piece.

Renowned furniture maker Tage Frid used the screwdriver's shank to carefully compress the gap (practise it first on ply if you wanted to try). But I'd clamp everything as close as they can get, and use Timbermate, which doesn't shrink and stays relatively hard after it cures.

Glue alone is all you need for this project. I use tape and glue for drawers, boxes and all sorts and never need dowels, dominoes or biscuits (except with my tea).


Peter

Hello, Peter.  These boxes will be used as a floating nightstand and will need to be able to withstand the weight not only of a table lamp but potentially books, etc in the open section.  I'm afraid that a mitered end grain joint wouldn't hold up to the weight without the added strength the addition of a domino/dowel would bring.   

 

[squall_line]

Hello, Peter.  These boxes will be used as a floating nightstand and will need to be able to withstand the weight not only of a table lamp but potentially books, etc in the open section.  I'm afraid that a mitered end grain joint wouldn't hold up to the weight without the added strength the addition of a domino/dowel would bring. 

In this case, would the dowels into each face be providing that much added strength, or just registration for fitting?

I would think that dowels parallel to the ground, in a mitered joint, would offer not only registration, but also strength against breakage as well as a parallel plane to clamp against.

Or a lock joint, or a lock dowel, or...?