Gluing Miters

[patlaw]

Miters and I don't get along very well. What's a good way to glue this box together? It's 2-1/2" x 6". The band clamps I have are too big for the short sides. The miters are not cut perfectly even though they were carefully cut on a Festool Kapex. I don't want to use any mechanical fasteners. The plywood is 3/4".

 

[JimD]

Mike,

I do not use miters a lot but you might try taping the pieces together while lying flat and then rolling them up into the box and taping the last joint. You may need to use epoxy or construction adhesive to fill the gaps.

Jim

 

[Mike Davis]

Even Festool sometimes needs to be adjusted. Your saw is off and you should get it set.
I spent part of last Sunday adjusting a Saw Stop table saw and checking a Festool Kapex.
Part of the yearly maintenance that should be done on all shop equipment.

As to the problem at hand I would use Gorilla glue, it expands to fill gaps.
As Jim pointed out, tape is a great way to clamp small items like this.

 

[Jeff]

One miter angle may be different than the other one by just a fraction of a degree. Example: 45.1 degrees and 44.9 degrees = 90 so the 2 angles are truly complementary. Ideally they'd be 45 and 45 on your Kapex.

https://ncwoodworker.net/forums/index.php?threads/miters.65642/

This miter jig by Gary Rogoswki is pretty good and will give complementary angles.

Picture-Frame Jig that Masters the Miter - FineWoodworking

The miter joint is an elegant and straightforward method for joining parts that meet at an angle without showing any end grain. In this video, contributing editor Gary Rogowski explains […]

www.finewoodworking.com

I have these web clamps from Lee Valley which work nicely on mitered joints.

16' Web Clamp - Lee Valley Tools

www.leevalley.com

 

[Dave Richards]

I agree with Jim. Epoxy with a bit of sanding dust or even white flour as a filler can go a long way to filling the gaps. If I was having a difficult time with the miters in an application like yours and couldn't get all the miters to close properly, I would cut them so they are open on the inside and closed on the outside. Then use thickened epoxy to glue them up.

 

[Mike Davis]

Kapex is pretty easy to adjust for perfect miters.

 

[Tim Sherwood]

When I need to cut a miter I use a Wixey gauge to set my table saw. Then clamp the workpiece to a sled so it can't creep .

 

[patlaw]

Thanks for the comments and suggestions. I'm going to try the tape thing again. Last time I tried it, the box didn't sit flat on the table.

Kapex is pretty easy to adjust for perfect miters.

I don't think the problem is the Kapex.

 

[bob vaughan]

Use a packer's knot. Lasso it with 1/4" (or less) rope and pull the standing end tight. Use at least two ropes for that wide of an assembly.

 

[Skymaster]

before the tape, tighten it all up and check where the miters contact each other, IF it is square and the front is open, re cut the INSIDE BACK, if you cut 45 then see if saw will give you 50 ish degrees just be sure you do not cut the front. Also use a plane to back cut. Just need clearance to close the front of the miters

 

[Jeff]

So the miters from the Kapex are 45 degrees each and 2 of them should go together. Take a front, back, and side piece (3 pieces) and see if they fit together.

Maybe the 4 pieces are slightly long and need to be shortened with a shooting plane. ????????????

 

[Mike Davis]

I can show you how to make your miters meet like this.

 

[Mike Davis]

Thanks for the comments and suggestions. I'm going to try the tape thing again. Last time I tried it, the box didn't sit flat on the table.

Saw may be off in both directions, fence as well as tilt. So not 45 degrees in miter and not 90 degrees across the width of the board. This is what all the evidence points to.

 

[patlaw]

I can show you how to make your miters meet like this.

That sounds like a deal to me.

 

[Graywolf]

Yep, your Saw needs tuning. Something you need to learn along with all the other things to be learned about woodworking. Take Mike up on his offer.

 

[Jeff]

That sounds like a deal to me.

Take Mike up on his offer.

 

[Gofor]

To hold the miters pictured together , you may need to use cross splines to ensure the joint has the strength to stay together. I agree with Mike that the saw is off in at least one dimension, or the work is moving (coming out of alignment) during the cut. Sometimes on a bevel cut, the wood will ride up the blade when being cut, throwing the angle off.

 

[nn4jw]

Not cutting the paired pieces to the exact lengths can cause problems as well. If you are hand holding the pieces and/or cutting to a laser you will rarely be exact.

 

[bbrown]

I agree - Splines really help align, strengthen, and make gluing much easier. After making any necessary adjustments with your machines, to get a better fit I often use my disc sander to fine-tune mitres.

 

[Rwe2156]

Splines and bar clamps