dowel joints create wobly joint: not enough glue?

[Paulh Tremblay]

I just glued up two carcasses using the Jessem dowel jig. One of the carcasses has strong, rigid joints. The other actually wobbles. I wonder if this is because I did not use enough glue? I was afraid of using too much, since the dowels fit tight and I didn't want a blowout in the MDF. For the second carcass (which doesn't wobble), I used a lot more glue.

Another reason for the joint failure might be the entire time for glue up. I went a bit over 10 minutes before I could finally apply the clamps and pull together the dowels. For the second cabinet, I used a rubber mallet right away to connect the two boards.

For each joint I used 4 dowels over 24 inches, by the way.

[Phil Thien]

Four dowels over 24" isn't many dowels.

If you are gluing just the dowels you aren't going to find much racking resistance until you install a back.

The unit where you used more glue probably had sufficient amounts of glue squeeze into the butted stock, and that will make the unit more ridged. BUT, those butted joints aren't super-strong and I'd get a back on the unit to prevent damage from any possible racking.

[glenn bradley]

Dowels with grooves prevent hydraulic lock and blow outs so you can squirt more confidently. Try doing glue-ups in sub assemblies so you don't have as many joints to worry about at one time. This shortens your time and number of maneuvers and makes for a lower heart rate ;-)

[Mark Bolton]

Dowels with grooves prevent hydraulic lock and blow outs so you can squirt more confidently. Try doing glue-ups in sub assemblies so you don't have as many joints to worry about at one time. This shortens your time and number of maneuvers and makes for a lower heart rate ;-)

Just as a note,.. spiral grooved and fluted dowels can still cause tons of blowouts if your using a mallet. Not gonna happen drawing together with clamping but a mallet blow will blow out solids l, ply, mdf, etc., even with grooved.

I've had it happen several times when guys get going too fast and they start whacking the dowels in fast especially in end grain and smaller parts.

[Paulh Tremblay]

Four dowels over 24" isn't many dowels.

If you are gluing just the dowels you aren't going to find much racking resistance until you install a back.

The unit where you used more glue probably had sufficient amounts of glue squeeze into the butted stock, and that will make the unit more ridged. BUT, those butted joints aren't super-strong and I'd get a back on the unit to prevent damage from any possible racking.

Almost everything I've read says four dowels is more than adequate for a cabinet. Is that wrong?

As a matter of fact, I did use glue on the edges of the second cabinet. I know that the glue on butt joints isn't very strong. I glued up some test edge boards, and to show some guys at work that glue is stronger than the actual wood, challenged them to break apart the joint. To my surprise, 30 seconds later the joint was apart. The glue had not failed; instead, the MDF surface had ripped apart.

I would have thought dowels would have created enough rigidity, but you believe that there is nothing wrong with the amount of glue, that I just need to add my back?

[Mel Fulks]

Did the surfaces completely pull up? If not the joint can be wobbly even if the dowels are well glued. The method I like is
to cut the dowels from linear birch or maple dowel stock, drive them through a non cutting thick dowel plate , use yellow
glue thinned with a little water. I've converted management in a couple of shops to that method by demonstration. A dowel glued into a block in that manner can be band sawed length wise and will not separate from the block without breaking.

[Wade Lippman]

With modern glues butt joints are plenty strong, though I am not sure what a butt joint would even be with MDF. Obviously I haven't seen your cabinet, but 4 ought to be plenty.
A properly made dowel shouldn't require very much glue at all. Most glues shouldn't care about 10 minutes open time, but you don't say what glue you used.
Perhaps you had some undersized dowels, but even if you didn't use any dowels the joint shouldn't be wobbling. It might break easily because of the MDF, but it shouldn't wobble.

[Phil Thien]

Almost everything I've read says four dowels is more than adequate for a cabinet. Is that wrong?

As a matter of fact, I did use glue on the edges of the second cabinet. I know that the glue on butt joints isn't very strong. I glued up some test edge boards, and to show some guys at work that glue is stronger than the actual wood, challenged them to break apart the joint. To my surprise, 30 seconds later the joint was apart. The glue had not failed; instead, the MDF surface had ripped apart.

I would have thought dowels would have created enough rigidity, but you believe that there is nothing wrong with the amount of glue, that I just need to add my back?

Well I assume this is a pretty large cabinet, based on the 24" depth. What I can tell you is that a large cabinet being held with four dowels in each corner may be a bit wobbly until a back is installed.

On the # of dowels, I think I would have gone with at least six or eight, which doesn't seem like a heckuva lot more dowels, but four dowels (two at extremes and the others spaced 8" or so apart) just seems insufficient to me.

[Paulh Tremblay]

A few more notes. I put the back on and still get some wobble at the front of the cabinet. I used titeboand type 3 glue. The joints of the wobbly cabinet did not fit absolutely tight. I used Jessem dowels, and they are so tight if I had dry fitted the carcass with these joints, I would have had a very hard time pulling the pieces apart for the actual glue up.

I think I will try putting in some Miller dowels to see if that fixes the problem, and to let me know the cause of the problem. They are just shop cabinets, so the appearance won't matter. For my finish cabinets, I will have figure out what caused this problem. I have made several MDF boxes and never had this problem.

I will also change the way I do glue up. I will make each joint tight as soon as I have the dowels in, working one joint at a time, and then put clamps on the whole carcass.

Any tips for making glue up go faster with dowels? I spend a lot of time with a brush spreading on the glue for each dowel.

[Prashun Patel]

I'm usually slow to get things clamped up too. This has not resulted in wobble, but snapping. Glue failure for me has been digital, not analog.

Can you post a picture? I would have suggested that the MDF was the culprit, but given that the other one feels fine, that seems unlikely. It is possible that when you forced the too-tight joints together on the wobbly carcass, the mdf swelled or ripped.

[Adrian Mariano]

Any tips for making glue up go faster with dowels? I spend a lot of time with a brush spreading on the glue for each dowel.

When I did a doweled carcase recently I had something like 7-8 dowels on each joint. To make gluing go quickly I put some glue into a small cup and dipped the dowels in and then wiped off the excess on the side of the cup. I also applied glue to the rest of the joint using a glue bottle with a roller attachment. (The one from Rockler with the grooves works much better than the one I got from lee valley with a smooth roller.) I tried to get each joint tight before moving on to the next one, because once the glue grabs it is very hard to make it move. So I would put one joint together and then clamp it to get it tight, and then take the clamps off to do the joint at the other end and then put the clamps back on.

[Mark Bolton]

A few more notes. I put the back on and still get some wobble at the front of the cabinet. I used titeboand type 3 glue. The joints of the wobbly cabinet did not fit absolutely tight. I used Jessem dowels, and they are so tight if I had dry fitted the carcass with these joints, I would have had a very hard time pulling the pieces apart for the actual glue up.

I think I will try putting in some Miller dowels to see if that fixes the problem, and to let me know the cause of the problem. They are just shop cabinets, so the appearance won't matter. For my finish cabinets, I will have figure out what caused this problem. I have made several MDF boxes and never had this problem.

I will also change the way I do glue up. I will make each joint tight as soon as I have the dowels in, working one joint at a time, and then put clamps on the whole carcass.

Any tips for making glue up go faster with dowels? I spend a lot of time with a brush spreading on the glue for each dowel.

I am no dowel aficionado but just shipped a job Monday that had perhaps 600-700+ 1/2 x 3 dowels in it (it was in solids though)... My only guess would be your box with the wobble didnt see enough clamping pressure to draw the joint dead tight. Whether it was starved or not who knows but I'd guess the clamping was the main issue. Whether that was because of too much time to get the box assembled and the dowels locked up, or trash in the holes, shallow holes, or some other reason who knows.

For a shop cabinet or a cabinet box I couldnt see a need for more than 4-5 dowels per joint (16-20 dowels for the box).

As far as speed and assembly goes, when we dowel, there is very little brushing if any at all. I run the glue in cheap squeeze bottles (like a ketchup bottle). For an edge glue up, I run a bead (fast) down the butt joint, looping glue at each dowel hole around the rim of the hole in hopes that it clings to the edge of the hole and rolls down a little bit rather than just dropping straight to the bottom of the hole. I then grab one dowel and hold the dowel with its long edge on the board and using the skin on my fingers as a bit of a spacer and a smooth motion I walk the length of the board using the dowel to spread the bead into an even film across the edge of the board. At the end of the board I stick that dowel in the first hole and tap in in with a wood mallet. Then peck in the rest of the dowels for that joint and repeat for all the other joints. The dowels are all dry. I dont brush glue on the dowels but occasionally with very deep holes I will use an acid brush to swab the hole a bit mainly to get the excess glue out of the hole. Then I glue the mating pieces holes the same way, rimming the top of the hole with glue. Then I knock the pieces together as far as I dare with a mallet and a block (if necessary) and draw the parts together super tight with clamps. For your MDF boxes Id say you'd need cauls to apply even pressure with two clamps. And I clamp the H#$$ out of it. There is always squeeze out with dowels for me because as the dowels come together the fluted dowels eject the excess glue but I would rather have plenty of glue in there rather than not enough. Its a super fast, assembly line, type process.

I dont dowel cabinet boxes but I could see an advantage (if your slow) in assembling a side and a bottom, then a side and a top, and then completing the box in a third glue up but man that would seem like a lot of work. I cant see how you couldnt get 16-20 dowels assembled with 4 clamps and cauls in time but if your doing the Norm style of construction applying glue to all surfaces, spreading it all with an acid brush, applying glue to all your dowels like your picaso, then yeah, you wont make it. Id rather clean up a little squeeze out and ditch the brush.

P.S. I have never found parallel clamps strong enough to draw multiple dowels together with very tight fitting dowels. Even on this last job when I had used up all my Ibars and 3/4" pipe clamps I tried to get a few more parts in clamps using parallels and they just wont cut it. They dont have any where near enough clamping force to draw the joint tight but again, this was solids and 3" dowels. A carcass with short dowels is a different story.

[Paulh Tremblay]

Thanks everyone for the advice. Mark, your post was very detailed and helpful. I will use your method along with Adrian's. while it might be theoretically better to make sure all the dowels are coated uniformly, that won't matter if you take too much time to clamp them.

I didn't realize there was a difference between parallel and bar clamps. You just saved me some money. Something like the Jorgenson I bars will work, no?

http://www.amazon.com/Jorgensen-7236.../dp/B0000224CH

[Mel Fulks]

Adding a little water make it easier to get the glue on quickly besides making the dowels swell some. A small amount of
water thins yellow glue a lot. In my experience grooved dowels do not swell as advertised without water nor do the compressed dowels I described. That is not saying they won't hold.

[Myk Rian]

instead, the MDF surface had ripped apart.

MDF is pressed paper.
Or at the least it's darned close to being that.