Replies

1. 
   Rob_Millard | Mar 09, 2001 03:26am | #1

   *
   Only on rare occasions, (not in over 20 years) have I used a jointer to make edge joints. I much prefer a hand plane for this, so I’m not even close to an authority, on jointers. If you were to feed alternating faces through the jointer, then if the jointer were out of square, the resulting angles would complement each other, and the panel would be flat. I plane my glue edges with both boards in the vise face to face, this way I don’t have to worry about getting them at perfect 90 degree angles. You do want a very small hollow in the joint (along the length), as this puts more pressure on the ends, where a joint is liable to open up. Achieving this slight hollow, on the jointer was, for me nearly impossible; more often than not I got just the opposite. I guess you could solve your clamping problem by gluing up pairs of boards, until you get the full panel made. This way you only have to deal with one joint at a time. Also, it is a good idea to put only a thin film of glue on the joint, because the glue acts like grease, and the boards just slide around as the clamping pressure is applied. I deal with this problem, by sprinkling a pinch of play sand into the glue, after it is applied to the joint (keep it in the center of the edge, so it won’t dull the edges of your tools when you surface the panel). The sand keeps the pieces from sliding around. You don’t need much sand at all, only a few grains will eliminate the movement.

1. 
   Mike_Maines | Mar 09, 2001 08:05am | #2

   *Bill, one more thing to check on your jointer is that the infeed and outfeed tables are parallel. If not perfect, there may be gibs that you can adjust, or use soda-can slices of aluminum as shims to get the tables perfectly parallel. When you feed stock through the jointer, once there's some wood on the outfeed side, put all the downward pressure on the outfeed table. Theoretically you shouldn't have to, but it seems to help get good edges. I still almost always clean the joint with a jointer plane.When glueing, it helps tremendously to use cauls, or boards across the width of the panel, sandwiching the boards. Use hardwood (1" x 1-1/2" or so) on top, preferably with a slight curve along its length. For the bottom make up some plywood or solid wood "T's", 4-6" high, to act as stands and to clamp the cauls against. Put glue on the edge of the boards, hand-fit them together on top of the "T's", clamp the cauls up tight, then, last, pull the joints tight with pipe clamps or K-body clamps. Don't overtighten, leave some glue in the joints, just pull the joint tight. Your panels will be flat, the joints flush, and the worry reduced. No need for biscuits. There was an article in FHB in the last year or two about glue up strategies, that probably had some more tips. Good luck,MM

1. 
   Danford_C._Jennings | Mar 09, 2001 05:53pm | #3

   *Bill,FWIW, a scarfed joint is stronger, easier, and the more "accepted" way of joining two ply wood panels, at least in boatbuilding. The typical ratio is around 11:1, but can vary.Dano

1. 
   Jim_Hassberger | Mar 09, 2001 06:47pm | #4

   *Even if the edge is perfectly jointed, even a slight imbalance in clamping pressure can open the joint, so its important not to over-tighten. In fact, I often use a "rubbed joint" in which no clamps are used. To make a make a rubbed joint, join the boards as usual, finish with a very light pass using a jointer plane on both boards in the same pass -- clamp the boards face to face, carefully aligned, and do NOT hollow the center. Clamp one board vertically with the joint edge up, apple glue to both edges, then place the secong board on top. Slide the boards together a little along the length (the "rubbing" part). As you do so, you will feel the glue start to grab. Stop and carefully align then and leave it for 15-30 minutes. If you want to, after the delay, you can move them against the wall or such. I prop a few sticks along the wall to support the assemble in a near-vertical orientation.By the way, clamping the boards face-to-face and jointing both edges at the same time works well on the jointer too, and compensates for any fence misalingment.

1. 
   Mike_Maines | Mar 11, 2001 12:18am | #5

   *Jim, I also rub the boards together until they grab, it helps spread the glue. How do you keep the boards aligned with each other, though? MM

2. 
   David_A._Brown | Jun 11, 2001 03:09am | #6

   *For the last 5 or six years, I've answered every question about "what do you want for (birthday, christmas, etc)?" with "clamps. Any kind, any size!".So now I've got a large collection, mostly of "quick grip" bar clamps. The full size versions get used often for clamping multi-board panels for glue-up. I've also got several miniature quick grip clamps, and they are PERFECT for pinching the edges of boards together at the seam. You can't clamp them too tight. The plastic pads don't stick to the glue line. They hold each board aligned as the larger clamps pull the joints tight. After about 10 minutes, I pull all the miniature clamps off and wipe clean their pads and the glue smear beneath them on the panel seams. I assemble my glued panel vertically. Stand the first board on edge, apply glue to it and the mating edge of the next one. Stack the second board atop, and align with miniature clamps at the ends of the seam. Continue with sucessive boards. Often I'll clamp the stack vertically to the table. Of course, quick grip clamps are good only up to about 24". The longer ones flex too much, in my experience. BTW, I've never been able to clamp panels "too tight" with quick grip clamps. I have seen it done too many times with screw handled bar clamps and pipe clamps. Squeeze too tight, and you can starve the joint of glue. Too much of it gets forced out.Dave

3. 
   Jim_Hassberger | Jun 13, 2001 10:06pm | #7

   *Mike:Sorry, it's been a while since I looked at this thread.Once the joint is rubbed and grabby, I just keep the assembly in the vise without disturbing it. If the assembly is carefully aligned carefully plumbed in the first place, once grabby it doesn't (or at least very seldom) move.