Clamping a 22.5 degree miter

[Hal Flynt]

Some history.

I am building a corner cupboard which has a face frame that makes the 45 degree transition from the 7" piece that come out 90 to the wall and then 45 to a 3 " piece at the edge of the front. (sorry no pictures)

I made the 22.5 degree miters in each piece, cut biscuit slots for alignment and the dry fit went really well. When I used Titebond III for the glue up and worked fast, the little clamping ears I made broke and it got tense. I ended up using my Bessy's to restrict the edges and used a number of smaller bar clamps with pads to close the top of the joint. When I took them out of the clamps, the points were really great, but I did notice that the back of the joint wasn't as tight. I don't think these joints are ever going to fail, but will be doing it again and would appreciate any insight.

Thanks in advance!

[Tom Sontag]

Tape.

I just glued up a compound miter and was very pleased that a fat strip of masking tape along the joiint was all I needed for glueup. Well, that and some pressure closing the joint (and I used tape there too). I am far from a miter joint guru, but next one I get will receive the same treatment.

[Rick Lizek]

One common way is to glue angled clamp ears on. Just a simple rubbed glue joint. Typically a piece of paper is place between the block and the piece you are gluing so when you knock it off it doesn't take wood from the main piece. I've also used double stick tapel like carpet tape. Whatever works.

[Jamie Buxton]

Another clamping assist is to build clamping hooks. They're just piece of scrap plywood cut so that they have a finger which hooks around the end of the panel away from the glue edge. Near the glue edge, they have a clamping ear pretty much like the ones you've used. Compared to glue-on ears, the nice thing about the hooks is that there is no glue on your finish surface.

[Steve Cox]

I lay out the mitered pieces flat on the assembly table(face up) and then run pieces of tape across the joint. When you pick up the pieces to their proper angle the tape has enough give to tightly clamp them together. Longer pieces of tape across the back will hold them in place. BTW I usually don't use biscuits with this. If it is long grain to long grain, it's not necessary.

[Hal Flynt]

Thanks guys, good ideas.

I like the tape idea and almost used it, but went with the biscuits for alignment. This piece is 7 feet long and I was concerned that it would slip. Do you run tape lengthwise, then cross wise across the joint or crosswise, then lengthwise?

I have this idea to run by you. I thought about dry fitting on the plywood carcass with a small shim near the mitered corner, drilling pilot holes for the finishing screws I use to secure to the top and bottom ( I am putting these at the top and bottom where molding will be applied). Apply the glue, snug the pieces together with the shim. Drive the outside screws, remove the shim then drive the inside screws thus applying pressure along the joint.

[Bill Arnold]

... I like the tape idea and almost used it, but went with the biscuits for alignment. This piece is 7 feet long and I was concerned that it would slip. Do you run tape lengthwise, then cross wise across the joint or crosswise, then lengthwise? ...

I run clear packing tape the length of the miter -- double layer for extra strength if it's large 3/4" panels. Then flip the panels over, wipe glue along the inside of the joint, bring it together and hold the two sides in place with blue tape.

Regards,

[Steve Cox]

I run tape across the joint. I feel it holds better and it gives the squeeze out somewhere to go. The longest I've used this technique with is about 3' for some table legs that I do frequently. Another good option here would be to run a spline the length of the joint. If I understand correctly this is a carcase that will not be seen top or bottom so through splines would work and be easier to align than biscuits. One other thing on direction for tape. While I think I understand the idea of running the tape along the joint is too keep it tight everywhere, running it across the joint allows you to verify that as you go. That's important to me, may not be so to you.

[Bill Arnold]

I run tape across the joint. I feel it holds better and it gives the squeeze out somewhere to go. ... While I think I understand the idea of running the tape along the joint is too keep it tight everywhere, running it across the joint allows you to verify that as you go. That's important to me, may not be so to you.
Alignment is very important, of course. That's why I use CLEAR packing tape along the length of the joint. As the tape is applied, it's very easy to see if the joint is tight. With the tape secured along the entire joint, all of the glue squeeze-out goes to the inside. I've used this process on pieces up to about 7' long.

Works for me...:)

[Hal Flynt]

Alrighty then.

Tape it is. I should get to this point in about a week, so I will let you know how it went.

Thanks all!!!