Gluing End Grain is a No No Or Is It
- Thread starter Mini Me
- Start date
chrisrosenb
Member
- Joined
- Sep 1, 2007
- Messages
- 1,265
My 50 + years of experience in woodworking shows that this is not how it works in real life.
I only know that I can break any end-grain to end-grain joint with my bare hands, and I just did yesterday to a miter joint on end-grain (moulding) which was also held with the aid of two brads 2" long. I also treated the joint with sizing in the glue-up process. (A very very small minority of woodworkers even think that a miter joint is not an end-grain joint.)
Michael Kellough
Member
- Joined
- Jan 23, 2007
- Messages
- 7,096
Like many things, it depends.
Some species like oak will reject too much glue. Some species will suck so much glue that the joint will be too dry.
You can get a long lasting end grain glue joint on species that absorb glue like softwoods and softer hardwoods like poplar and cherry if you monitor the glue absorption and and more if needed before clamping.
Species that don’t glue well directly can be reinforced with a loose tenon.
Some species like oak will reject too much glue. Some species will suck so much glue that the joint will be too dry.
You can get a long lasting end grain glue joint on species that absorb glue like softwoods and softer hardwoods like poplar and cherry if you monitor the glue absorption and and more if needed before clamping.
Species that don’t glue well directly can be reinforced with a loose tenon.
Box maker Matt Kenney says he makes a lot of boxes without reinforcing the miter joints. Some others, notably Doug Stowe, use splines, etc. for all their miter joints.Michael Kellough said:
I've done a few miters without anything other than sizing and glue. BUT those pieces are not critical builds, and if disjoined, I can easily glue them back.
For serious pieces, I'll never risk any end-grain joints using glue alone. A miter picture frame or shadow box, for example, can cause damage to the treasured contents if it breaks apart while hung. I won't listen to anyone telling me that it's ok to just glue a miter or bevel joint.
Attachments
- Joined
- Apr 13, 2011
- Messages
- 4,550
The folding mitre joint, especially with MDF, works really well...
Peter
Peter
mino
Member
- Joined
- May 5, 2016
- Messages
- 1,984
True.Peter Parfitt said:
Though MDF does not have a grain direction ... and a mitre joint is not a pure end-grain joint either.
In the end, the point always is how strong does one need the joint to be. Joint being stronger than the wood is cool, but not required in many cases.
MDF is wood that doesn't move. I use MDF only for jigs.
Wood movement weakens miter joints constructed with natural lumber as the joinery test article done by Fine Woodworking points out, making glue unreliable, unless the joints are never subject to stress (such as Kenney's boxes).
Wood movement weakens miter joints constructed with natural lumber as the joinery test article done by Fine Woodworking points out, making glue unreliable, unless the joints are never subject to stress (such as Kenney's boxes).
JeffSD
Member
- Joined
- Sep 5, 2019
- Messages
- 47
Interesting topic and video.
If Patrick Sullivan has the time and inclination, I'd love to see a part II video that includes a broader range of wood species.
I build a lot of miter joint frames for my photography and have come to the conclusion that dowel + glue, or spline + glue is the way to go. This is especially true with tropical hardwoods whose high oil content makes them more resistant to conventional, water-based glue.
Here's an article from the Wood Database that I found helpful:
https://www.wood-database.com/wood-articles/gluing-oily-tropical-hardwoods/
If Patrick Sullivan has the time and inclination, I'd love to see a part II video that includes a broader range of wood species.
I build a lot of miter joint frames for my photography and have come to the conclusion that dowel + glue, or spline + glue is the way to go. This is especially true with tropical hardwoods whose high oil content makes them more resistant to conventional, water-based glue.
Here's an article from the Wood Database that I found helpful:
https://www.wood-database.com/wood-articles/gluing-oily-tropical-hardwoods/
Cheese
Member
- Joined
- Jan 16, 2015
- Messages
- 12,503
This is a very interesting video and I'm glad it was posted. It's hard to argue with Patrick's testing or with his procedures. He certainly seems to back up every conclusion with facts and data rather than just heresay. I'm surprised that there aren't more vociferous responses than there are. Maybe everyone's in the same boat as me...I just don't know.
My first knee-jerk reaction was that his conclusions are wrong, however, after evaluating his testing methods and his testing equipment, I'm not so sure. I'd also like to see some further evaluations because there may be something here.
His testing thoroughness is something to certainly hold in high regard.
My first knee-jerk reaction was that his conclusions are wrong, however, after evaluating his testing methods and his testing equipment, I'm not so sure. I'd also like to see some further evaluations because there may be something here.
His testing thoroughness is something to certainly hold in high regard.
thudchkr
Member
- Joined
- Dec 13, 2007
- Messages
- 279
What seems to be missing from the equation is that and end-grain glued joint is stronger than short grain wood fibers. By testing all these using these small blocks, his small wood samples all have a small cross section of long grain wood. Would you ever try to use a shelf made with the grain running opposite to the length of the shelf? Not likely because the wood itself does not have it's strength in that orientation.
It is my belief that he is not actually testing an end-to-end grain joint against an end-to-side grain joint, and likewise to a side-to-side grain joint. He is instead testing the joint, and the adjoining wood, which due to the short grain samples, are the points that are actually failing, not the joint, as demonstrated in his presentation.
He showed that the long grain of the wood was much stronger than any of the joints that he tested, but never showed a joint that extends a sample in the long grain direction, joined by a side grain-to-side grain joint. He should take another of his samples and glue them face to face, using only 3/4 of an inch for his overlap to keep the size of the actual glue joint the same, and then test that against his other samples. I would be surprised if he did not come out with a much different summary.
A better way to describe the results of his test would be, "An end grain to end grain joint is stronger than the strength of short grain wood fibers."
It is my belief that he is not actually testing an end-to-end grain joint against an end-to-side grain joint, and likewise to a side-to-side grain joint. He is instead testing the joint, and the adjoining wood, which due to the short grain samples, are the points that are actually failing, not the joint, as demonstrated in his presentation.
He showed that the long grain of the wood was much stronger than any of the joints that he tested, but never showed a joint that extends a sample in the long grain direction, joined by a side grain-to-side grain joint. He should take another of his samples and glue them face to face, using only 3/4 of an inch for his overlap to keep the size of the actual glue joint the same, and then test that against his other samples. I would be surprised if he did not come out with a much different summary.
A better way to describe the results of his test would be, "An end grain to end grain joint is stronger than the strength of short grain wood fibers."
I came across this video at another site. I made some observations.
1. End grain joints tend to have very small glue areas. A 3/4" thick x 4" wide board only has 3 square inches of glue surface.
2. Face grain joints tend to have far larger glue areas. Gluing up a 6' table using 3/4" thick board = 54 square inches.
3. And finally, I have glued up 3/4" plywood. Regardless of the direction, you get 3/8" end grain to end grain and 3/8" face grain to face grain. It results in a surprisingly strong box. With a 3/4" x 3/4" triangular section glued the length of the joint it becomes strong enough for a base cabinet.
1. End grain joints tend to have very small glue areas. A 3/4" thick x 4" wide board only has 3 square inches of glue surface.
2. Face grain joints tend to have far larger glue areas. Gluing up a 6' table using 3/4" thick board = 54 square inches.
3. And finally, I have glued up 3/4" plywood. Regardless of the direction, you get 3/8" end grain to end grain and 3/8" face grain to face grain. It results in a surprisingly strong box. With a 3/4" x 3/4" triangular section glued the length of the joint it becomes strong enough for a base cabinet.
Similar threads
