Epoxy may be my favorite new glue

[jteneyck]

I am making an exterior door following Joe Grout's basic approach.  Joe uses dowels to hold the components in alignment during glue up, I use loose tenons.  Joe's approach is really clever as it allows him to glue up the frame very quickly, so he can use TB glue w/o having to worry about it setting up before he has all the parts together.  But using loose tenons, 10 of them in this door, requires a lot more time to apply glue to both the mortises and the tenons.  I used plastic resin glue when I built the arched French doors, which has about the same open time as TB, but those doors only had 6 tenons and no center mullion.  Even then, it was a race against time, which I barely won.  So I knew I'd never get 10 loose tenons in place and the clamps on before the glue set up, so I decided to take a different approach. 

I used T-88 structural epoxy:



OK, not the cheapest stuff at about $24 for 8 ounces, and you have to leave it in the clamps for what seems like forever, but glue up is stress free.  It has an open time of at least 45 minutes, which turned out to be important because it took me nearly an hour to glue up this door.



Why so long?  I don't know, I'm slow.  There are 8 tenons 5" long x 4" wide, and 2 that are 2-1/2 x 1-1/2".  I applied glue to both surfaces to be joined, per the directions, using a little acid brush so that took some time.  Plus I applied glue where the stub tenons and dados meet.  Anyway, I made three 30 ml batches as I went along; used about half the bottle when I was done.  I started by gluing the center mullion to the two rails, and then added the stiles.  What was especially nice about the epoxy is how it acts as a lubricant before it sets; doesn't run much either.  The loose tenons slid right into the mortises even after sitting for 20 minutes while I prepared the others.  Clamp up took very little force to close the joints; again, it was like everything was greased.  And I never knew that epoxy could be wiped clean with lacquer thinner until I read the directions on the box.  Wow, did that make for a low stress job.  It wiped clean instantly, way easier than wiping TB off with a wet rag. 

I'm sold.  
 
John

[gMike]

I use epoxy quite a bit more than I used to.  The long open time is great and after you learn a few of it's tricks it be used as part of the finished product (filling knot holes, gluing different materials, etc.).  It isn't cheap but it meets some needs that Titebond just can't do.

[Steve N]

I never think to use epoxy, just don't. I think with that in mind I love it. My reason is the more improvements made in epoxy, the more improvements Franklin makes on their glues for open time, water/weather resistance, and all other aspects, so not long from now there will be a super PVA that will rival all. Franklin is always looking ahead, sometimes I wonder about the Ape folks, and Old Elmer.

[atgcpaul]

I'd probably try to glue it up all at once, too.

However, what's stopping you from gluing the center stile to the top and bottom rails, wait for it to dry, then gluing on the outer stiles?  Is it because it's harder to ensure that the center stile is 90deg to the rails which would then make it harder to glue on the outer stiles flush to the rails?

[jteneyck]

I'd probably try to glue it up all at once, too.

However, what's stopping you from gluing the center stile to the top and bottom rails, wait for it to dry, then gluing on the outer stiles?  Is it because it's harder to ensure that the center stile is 90deg to the rails which would then make it harder to glue on the outer stiles flush to the rails?

I could have done just as you suggested, but I would have had to dry assemble all the components to make sure the center stile was square to the rails, as you suspected.  Then I would have had to pull one stile, apply glue to everything, and clamp it back up, then repeat that on the other stile.  I just didn't want to go to all that effort when once and done was possible.  And I really have to say again how nice the epoxy was to work with a huge open time and easy clamp up compared to the rush that always seems to happen when using PVA glues. 

John

[JGrout]

I guess doing it for so many years I have just adjusted and moved on 

<<< PVA clamps and a tape measure to verify diagonals seems to work fine for me mortises or dowels 

then again I do not bother to put glue on dowels or tenons 


Just saying if I can manage most probably could as well 

I have done door  glueups that take over two hours to assemble 

it is about proceeding in a manner that allows work to continue in ongoing stages

I am not trying to ditz what John has done it worked for him; it is however unnecessary

[Robert Adams]

Yup epoxy is great stuff.  I usually buy my epoxy from Mas epoxy. Good stuff and fair prices. 

    I'm planning our garage doors and they will be mortice and tennon maybe drawbore as its strong and self clamping. The doors are only 9' wide so not hard to keep flat like a 16' door but they are 7.5' tall hence why i want to build them vs have them done and even using good quality lumber its still way cheaper to build them than even basic metal insulated doors. They will be epoxied at the joints as well.

[jteneyck]

No argument from me, Joe, I just want to point out to others that you don't need to glue in your dowels because a dowel can't slip (shear) in a tight fitting hole.  Nor would a tenon if it fit tightly in the mortise, but I make my mortises at least 1/16" wider than the tenon, usually even a little more.  That allows me some latitude both when milling the mortises and to adjust alignment during glue up.  However, the penalty for that flexibility is the joint must be glued to prevent shear and serves no function if it's not.  There is a lot of surface area to be glued with all those large mortises and tenons, and I need those joints to remain adjustable until clamp up, so it's easy to run out of time when using PVA glues if you (or maybe more correctly, I) try to do the glue up in one step. 

If my mortises and tenons fit perfectly time would be less of an issue.  Or I could learn to drill mating dowel holes accurately.  

John

[ez-duzit]

I use WEST epoxy exclusively for gluing, and generally pre-assemble complex fabrications to check fit before mixing the glue. The use of slow (or even extra slow) hardener helps give you time to do the entire assembly at once before the epoxy begins to go off.

[Sawdustd]

Hey All,  the above comments prove once again that there are many ways to skin a cat.   That's what I love about this forum.  The solution is: Whatever works best for you. 

Dave