Clamping mitred corner joints

[Spectric]

Hi all

This task always seems a struggle with various clamps and bits of wood so what ingenious methods are people using. This clip https://www.google.com/search?hl=en...QMIDA&uact=5#kpvalbx=_Y6OlX-S8OpKfgQahuK2oBw8

is using clamps that will hold the joint square but applying pressure through the joint and not across it so assume it is for squareness more than clamping pressure. I am looking at whether an easy jig could be made based around some bench dogs clamping along the axis of one piece whilst the other cannot move but all ideas appreciated.

 

[thetyreman]

I can highly recommend this clamp: Bessey Band Clamp BAN700

works for me and soon pays for itself.

 

[LBCarpentry]

Not tried them but always liked the look of these clamps

 

[TheUnicorn]

I don't often have need, but have on occasion used a makeshift band clamp. two blocks of wood put in the middle of each side, ratchet strap around everything with firm but not heavy pressure, push the blocks out to the corners by hand as even as you can, carry on this process, tapping the blocks out to the corners with a hammer if needed

https://www.instructables.com/Picture-frame-clamp/

 

[Argus]

The method that I favour - almost exclusively for picture frames - is the old fashioned Record corner clamps, (4 of the blue metal ones), in conjunction with glue and cross-grained splines placed about centrally in the mitre.
Occasionally I may apply a little lateral squeeze along each long side with a sash clamp to get the excess glue out.
I've had a set of four of these clamps for a long time and although they had a reputation for inaccuracy, they work well. The problem with the slightly skewed pressure, I found, was nothing more than filing off a few hard-to-spot bits of casting-clag on the faces and getting rid of the paint splodges in these area.


There are many ways to do this..... hope that this one helps.

 

[Doug B]

I can highly recommend this clamp: Bessey Band Clamp BAN700

works for me and soon pays for itself.

Another vote for the Bessey, useful for more than just 45 degree mitres

 

[Peter Sefton]

Band clamps and timber corner blocks for me.

 

[peter-harrison]

These are good. If you’re worried about damaging the surface you can tack on little blocks with hot melt glue

 

[Trextr7monkey]

For many years I ran a school workshop and lots of boxes were made with many different techniques used according to size.
for mass production of smallboxes a rectangular block in a plastic vase plate allowed boxes to be built square and either nipped with ratchet clamps or squeezed then wrapped with masking tape. Alternatively a wood work vice and single clamp or bench dogs with matching dogs on the moving vice jaw (Lervard benches) could get plenty of pressure on.
Bigger frames and toy boxes we tended to use ribbon clamps with plastic right angle blocks on the corners to aid assembly then some decent sash cramps.
We did have the metal record style corner clamps which tended to be used for frames.
Generally to get quality results we would fit floors in a routed grooves and where possible joints were cut on a Morso guillotine

 

[paulrbarnard]

I make up a lot of picture frames. My other hobby is photography. I'm just framing up some pictures for Christmas presents at the moment. I find band clamps tobe ideal. I have a couple of different ones from Amazon, including this one with a steel band. It's the one I tend to use pretty much all the time. It's massine and can be used for carcass glue up as well.

 

[Peri]

No good for picture frames, but I bought a couple of these clamp add-ons, on a whim. Not used them, yet to see how good they work.




Failing that I have some Rutlands 'precision' clamping squares that I took to work and milled square, which I clamp to.

 

[stuartpaul]

I use a bog standard ratchet strap with corner blocks. Can get a lot of pressure if needed.

 

[Farm Labourer]

I use a bog standard ratchet strap with corner blocks. Can get a lot of pressure if needed.

Inspired by this and keen to finish the lid of a box that is mitred, I cut some "corner blocks" today and they are currently clamped whist the glue dries!

 

[custard]

This task always seems a struggle with various clamps and bits of wood so what ingenious methods are people using.

It's one of those questions where it all hinges on what kind of mitres are being glued.

Band clamps have been mentioned several times, they have their uses but don't forget that a band clamp is basically trying to turn a square frame into a circle, so the trick is to apply the bare minimum pressure.

For most picture frames a band clamp isn't really the best choice, it's cheap and convenient which is why it gets used, not because it's the best solution. The professional clamps for picture frames tend to take advantage of the fact that a picture frame has a rebate, and the inside surface of the rebate will never be seen. Consequently they usually have devices with toothed cogs that grip inside the rebate and pull the mitre faces together while applying pressure perpendicular to the glued surfaces.

Another solution is the pointed spring clips that have also been mentioned. These work best when you have a method of holding the mitre in position and using the special pliers that hold the clips open. Trying to apply the clips just by hand, especially if you're on your own, is a frustrating recipe for misaligned mitres.

For larger mitred frames it's normal to have some kind of loose tenon, either a Domino or a biscuit. Personally I prefer biscuits for this application. A Domino (or a dowel) often needs to be tightened up progressively on all four corners at once in order to get it assembled, where as with biscuits you can usually tackle the corners one at a time. Truth be told most makers will sand the Domino before doing a mitred corner, the reason is PVA can sometimes "grab" part way through an assembly, so on mitres you really want a more relaxed fit to preclude any risk of this.

For mitred cabinets adhesive tape is a proven technique. A key thing here is to use a decent brand masking tape, both for the better "stretchiness" of the fabric and also because cheap masking tape has a bad reputation for pulling up fibres of wood from the surface.

 

[AJB Temple]

Custard is the professor on this. Good tip on the dominos. I do exactly that as I found it out myself as a solution one day. Most of the time when I am clamping mitres or corners it is on drawer boxes or small storage boxes or simple picture frames. I don't get on with band clamps at all - mainly because if I want to add a bit more pressure they tend to pull the joints out of square. I want mitred joints to be perfectly super tight.

I do quite like the Bessey mitre clamps like these. They still work even when the joint has two different timber sizes. They cost about £25 if you shop around (do NOT buy the cheap Stanley and similar knock offs - they are nowhere near as good):

I've also invested in a couple of Kreg automaxx clamps like these. I forked out £33 each for these by shopping around and I really like the accessibility for access to the joint for drilling etc. Not used them much yet. Again you can get cheap Chinese knock offs but I think you tend to get what you pay for - the Kreg hold tight and accurately. You can also use them to secure drawer divider internals.

 

[NDRiley]

My default is brown parcel tape. It works unbelievably well for minimal cost. As suggested above, a decent brand of tape is definitely worth the extra pence.

Lay all pieces end to end, slightly overlap the mitres and tape the back. The stretch in the tape “clicks” the pieces together when it’s assembled. Not sure what the clamping pressure is but I’ve not had a failure yet. I do tend to reinforce the corners with something eg splines.

I also seal the mitre surfaces with a bit of watered down glue before final glue up.

 

[Sheffield Tony]

For completeness - if you are willing to glue bits on temporarily, glue a triangular block on each side of the joint, so you can clamp across the blocks and get your pressure perfectly perpendicular to the joint surface. Saw/plane the blocks away when done.

No, I can't be bothered either, I use a band clamp.