Glue for miter joints in 3/8 material

[Ron Humphrey]

I would like to make 3/8 thick walled boxes out of various hardwoods. The sizes will vary but as an average they will be, approximately 6” x 9” & 4” deep. I have some experience with ½” thick miter joints with corner splines for strength that work well. I would like to avoid the splines in the 3/8 if possible.

Currently, for the ½” stock I apply a very little yellow glue (Titebond I or II. Elmers etc.) mixed with some water on my finger onto the end grain of all the pieces, wait until it absorbs into the end grain for a few minutes, but is still tacky and then add more glue and clamp up.

Is just glue, using the same technique, but without the splines, going to be strong enough? Is there a type of glue that would work better? Would epoxy be better than yellow glue? Any other techniques for assuring a strong joint?

[johnny means]

End grain to end grain joints are very weak. Generally they need to be mechanically reinforced. Sometimes epoxies will do the job, but they'll be ugly thick joints.

[Ron Humphrey]

That's why I'm asking if there is a glue/adhesive that overcomes the inherent weakness

[John Schweikert]

If you are dead set on a miter joint then I'd suggest a miter lock router bit. They make them for stock as thin as 3/8". Simple search:

https://www.google.com/search?q=3%2F...sm=91&ie=UTF-8

[Ron Humphrey]

Thanks John, I bit the bullet and bought one from Infinity. Received it last week, but haven't had time to run tests, but am a little leery of getting a good joint in 3/8 and fishing for others experience with glues for thin miters.

[John Schweikert]

Titebond II or III is a very strong bond but that material thickness is questionable with no additional support. I use epoxy a lot for a boat build and I don't think you want to go that route.

Hidden splines or decorative splines would add a lot of strength. A locking miter joint is easy on a router table and excellent strength. You have the bit, give it a go.

[Art Mann]

This may be an oversimplification, but why don't you build some joints out of scrap and do some destructive testing to see whether simple miters are satisfactory? I have built boxes out of 3/8" material with just precisely cut and well clamped miter joints and they held up okay. I don't like to do it that way because I think finger joints or decorative splines add visual interest as well as strength. I have used a lock miter bit quite a bit to make boxes with 1/2" material and it is not trivial to get good tight joints. Your table setup and cutting technique must be exactly right and your material must be of very consistent thickness.

[Ruperto Mendiones]

Infinity makes a gauge to set up a lock miter joint. Might be worth consideration as setup isn't easy.

[Jim Finn]

I make hundreds of boxes, mostly of 3/8" cedar. I miter the corners apply white glue and "clamp" with rubber bands. I glue the top and bottom on this frame ,finish, and then cut the top section off about an inch down from the surface of the top.. The top and bottom glued on makes the miter joint plenty strong for a small box.

[Mike McCann]

i am with Jim on this. for such a small box glue it without anything else will be strong enough

[Bill Huber]

Thanks John, I bit the bullet and bought one from Infinity. Received it last week, but haven't had time to run tests, but am a little leery of getting a good joint in 3/8 and fishing for others experience with glues for thin miters.

Ron, did you get the Lock Miter Master jig, it is an awesome little tool that really works. Setting up the lock miter can be a pain but the tool really makes it easy.

[Chris Padilla]

I always like to reinforce miter joints in some fashion but I'm with some of the other guys: this is a small, light piece and glue will likely be fine.

However, I would probably go through the muss and fuss and reinforce it with a spline or a small biscuit. They make FF biscuits for such an application.

[Peter Quinn]

Urethane glues are known to have some advantage over yellow glues on end grain miters and butts. They swell into the end grain considerably following the grain naturally and they don't suffer from moisture starve resulting in a weak bond. The issue becomes clamping, you have to resist the swelling action so the glue is forced into the end grain. Perhaps a hi pur hot melt set up might work? I know a local shop that glues outside mitered crowns up for cabinets with hi pur, you need a serious hammer blow to separate the parts once cured.

[Ron Humphrey]

Bill, I did get the Infinity bit & Jig. I hope to experiment with it this weekend.

[Brian Holcombe]

That's been my experience as well. If the joint will be stressed than I would reinforce it with a spline, but if it will not be than I would be comfortable with a simple miter and tight bond III.