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-7236-36-I-Bar-Clamp/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.

[Chris Padilla]

I use dominoes instead of dowels but the assembly is the same. I like to insert the dominoes into one side first, with glue, being careful to wipe up squeeze out. Sometimes this will be minutes ahead of time and other times it could be hours or a day or two ahead of time. Depending upon the complexity of the glue-up, I might do it in stages but use the other pieces dry just to hold the shape correctly of the glued pieces. If your dowels fit incredibly tight, you might have starved glue joints. The point is to minimize the length of time before you get your clamps on so I do everything I can to minimize that time. I often do dry runs; always have my clamps ready to go; glue ready to go (upside down so glue flows right away); brushes ready to go; damp sponges or towels for wipe ups; no disturbances from the family. You'll mess up a few glue-ups and eventually figure out a good system that works for you. Always keep in mind that the glue needs some room, too, so if joints fit so tight that getting them apart dry is a struggle or extremely difficult, then your joint is too tight.

[Mark Bolton]

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-7236-36-I-Bar-Clamp/dp/B0000224CH

Im probably well represented in the archives as a firm believer that parallel clamps are a complete and utter waste of money. Our go-to clamps are the 3/4" pony pipe clamps and the Ibars you posted. You can put together three of four of the 3/4" pony pipe clamps for the cost of a single parallel clamp. I just dont see the value (in parallels). You always need more clamps than you have so if I were going to populate my shop with 20 parallel clamps I would rather have 60-80 really nice pipe clamps. The I bars are invaluable and if you are on a one for one comparison I see no comparison. I know this wont ring true with many here but I would much rather spend my money on Ibars and 3/4" pony pipe clamps.

[Chris Padilla]

I do love my Bessey parallel clamps!! I've never had a situation where they could not pull something together BUT then again I am not a professional and don't rely on them to make a living. I do rely on them to keep me out of trouble and in the comfort of my garage/woodshop. :)

[Mark Bolton]

I use dominoes instead of dowels but the assembly is the same. I like to insert the dominoes into one side first, with glue, being careful to wipe up squeeze out. Sometimes this will be minutes ahead of time and other times it could be hours or a day or two ahead of time. Depending upon the complexity of the glue-up, I might do it in stages but use the other pieces dry just to hold the shape correctly of the glued pieces. If your dowels fit incredibly tight, you might have starved glue joints. The point is to minimize the length of time before you get your clamps on so I do everything I can to minimize that time. I often do dry runs; always have my clamps ready to go; glue ready to go (upside down so glue flows right away); brushes ready to go; damp sponges or towels for wipe ups; no disturbances from the family. You'll mess up a few glue-ups and eventually figure out a good system that works for you. Always keep in mind that the glue needs some room, too, so if joints fit so tight that getting them apart dry is a struggle or extremely difficult, then your joint is too tight.

Chris,
When you have squeezeout that you have to wipe up around a tenon, domino, dowel, you basically seal the joint. Especially if its days before the rest of the joint is assembled. There of course may be some benefit there if you really clean the daylights out of the area but again, man, that seems like a lot of work (for a compromised joint) unless you have such a complex glue-up that there is no other choice.

I cant imagine that I could clean up a doweled joint well enough to feel like all the surfaces are going to accept glue as well as if they were raw.

[Chris Padilla]

I rarely have much squeeze out. You just have to be careful with the amount of glue you squeeze in. Appreciate that I'm not (wife may beg to differ! :D ) really on any time crunch and even when I have squeeze out after driving the dominoes home, it ain't much. There is plenty of "non-spoiled" wood fibers for the glue to grab onto when I do my full glue-up.

[Mark Bolton]

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-7236-36-I-Bar-Clamp/dp/B0000224CH

Again, a shallow carcass glue up is different but usually (at least with straight fluted dowels) when you peck the dowel into the hole the glue will squeeze out into little pearls at every flute (unless youve got way too much glue in the hole then its a puddle around the dowel). This (to me) means that the glue has basically come up all sides of the dowel and its nearly completely coated except for perhaps the very tips of the flutes. Regardless, it would seem a lot faster to glue the dowel bores and stick an acid brush in there to swab the holes as opposed to brushing each dowel.

Dont know, its just about speed in my opinion. Of course quality and joint integrity as well, but those are a given.

[Phil Thien]

I squeeze glue into the dowel holes and they use a skewer to make sure the walls are evenly coated.

I use white glue so I have longer open time.

[Paulh Tremblay]

I added two Miller dowels per joint to the cabinet that had the slight wobble, and it still wobbles. Very interesting. It makes me think that most of the rigidity of my dowel joints comes not from the dowels, but from the glue to the surface. That further makes me wonder if dado joints aren't in fact better. If you performed a test in which you tried to tear apart the cabinet, dowel joints would easily prove stronger. However, cabinets are not usually stressed in this way.

Instead, cabinets are stressed by forces acting to make them out of square. Here, dadoes provide much more strength.

[Roger Rayburn]

Your wobble description suggests to me that your dowel holes are perhaps a tiny bit too shallow, as Mark suggests, and therefore it is impossible to completely seat the edges to each other. This is the same concept as a mortise & tenon. A joint with a shoulder is more stable than just a stick in the hole. Once the glue is dried, nothing should move. And, shoulders on M&T joints don't get glued. The stability depends on the glued stick in the hole and the unglued shoulder.

[Mark Bolton]

I added two Miller dowels per joint to the cabinet that had the slight wobble, and it still wobbles. Very interesting. It makes me think that most of the rigidity of my dowel joints comes not from the dowels, but from the glue to the surface. That further makes me wonder if dado joints aren't in fact better. If you performed a test in which you tried to tear apart the cabinet, dowel joints would easily prove stronger. However, cabinets are not usually stressed in this way.

Instead, cabinets are stressed by forces acting to make them out of square. Here, dadoes provide much more strength.

Its hard to say with any certainty without seeing the boxes and the wobble first hand but I think I recall you saying you had some that you assembled without a wobble. I cant honestly say that any box Ive assembled, dado or not, doesnt have some wobble before the back goes on. After the back is on I would guess I could still say there was some wobble in that you can always flex/spring the open end of the box until its in place/face frame/secured to adjacent boxes/etc.. Id guess the flex to be worse with MDF (I dont build boxes with MDF).

I will acree with you that over thinking the average cabinet box is easy, and often, done. Even a cheap home center box, once installed, can be more than adequately rigid. That said, it would be annoying while assembling them and Id want to find the problem.