I am putting together some boxes that have been mitred all around, they are sliding around and it takes me a lot of effort to put them together to stay and glue correctly. Anything I could do to make this easier? I do not want to use screws or anything like it because this is MDF with the front covered with a wood like look and do not want to wreck it as much as possible.
I thought it would be better to have pictures of the tape method for greater clarity as well as to future-proof things in case of changes to any of the external links provided in this and other Answers.
First thing you do is lay down the sides of the box flat on the table and apply tape across each corner joint:
Note tape is on the faces opposite the mitres.
Now flip over and you can apply glue to the joint surfaces.
To improve bond strength you may want to size the mitred surfaces with diluted glue 10-20 minutes ahead of time. If you plan to use any reinforcements to the mitred joints (e.g. keys, interior glue blocks, an epoxy fillet, brads/panel pins) this isn't really necessary but it is good general practice when glueing end grain.
Now roll the box up like this:
If you're not glueing on the base immediately you're done for now, put the box aside for a few hours for the glue to dry.
Pictures taken from this Craftsy article.
I have done something similar using baltic birch plywood for boxes that are up to about 8" by 8" by 8". The first challenge is to make certain that the miters are cut exactly 45 degrees. If you cannot achieve that, tight, closed joints are impossible (see How do I cut a 45 degree bevel on a table saw with consistent dimensions?)
When making a five surface box (no top):
- On a table top carefully tape the bottom to each of the four sides with the miters facing up.
- Apply and spread glue on each of the mitered surfaces.
- Fold all four sides upward and tape together.
- For clamping use large rubber bands. The more rubber bands the higher the clamping pressure. Also tighter rubber bands means more pressure.
If you are making larger boxes tape can still be used, but you might have to resort to band clamps. If not band clamps then a dozen or more larger opening bar clamps. Or a combination band clamps and bar clamps.
After applying the tape, it would be good idea to rehearse your clamping before applying the glue. That way, when the glue is in place, your clamps will be set to the correct opening and there will be less chance for one clamp slipping while tightening another.
If the box is big enough, you can use shop made corner clamps like the ones featured in this Wood magazine article.
If the box is too small for that, it might be a good candidate for gluing up using tape as clamps, as demonstrated in this Popular Woodworking article. Indeed, if it's small enough, like a small keepsake box, you can use one piece of tape, stick all the sides to it in order, and just wrap the whole thing up. At the very least, this should help stabilize the panels while you are clamping them together.
I have had good success by using a band clamp. Glue your corners, assemble it, make sure everything is square, and then ratchet it down with the band clamp. This allows you to get some good pressure on the joints.