Here is a couple pics that shows the pins method
A quick description:
Take strips of MDF and apply camper shell foam to both sides.
Clean both areas to be bonded with denatured alcohol and blow of with compressed or canned air.
Put horizontal sheet on top of foam strips. Make sure the area under the joint has foam under it, as much as possible.
Place vertical piece in joint position. Leave a 1/8" lip. Secure in place with angle bracket.
Insert thin shims between foam and horizontal piece to snug the joint up as evenly as possible. There should be no visible gaps, or as close to that as you can possibly get. Some recommend inserting shims under each pin. IMO if your table is flat enough you only need them where it is necessary.
For pins, I use 28 gauge picture hanging wire from Home Depot, cut a length about 6-8" and loop & twist so you can have a 'handle'. Also I use a good wire cutters to get a clean cut end on the part that is inserted - the cutter that comes with the wire sucks.
Push down on the lip and insert pins. I do every 6", roughly. Only insert far enough to create the gap, 1-2mm should do it. For thicker material (1/2-3/4") I go a little further.
Once all the pins are in place, go around and gently tug on each one. If one pulls out easily (or falls out while putting in other pins) then shim that spot. Don't push it in too far or you'll have pins falling out in other places - sometimes far away from the one you just shimmed (this is more likely on a top/bottom joint). Repeat until you can go all the way around the joint without tugging a pin out.
Take canned air and blow out the joint. This will also reveal loose pins. If they move, that's probably OK. But if the air blows them out of the joint then that one was a bit too loose. I don't use compressed air here because it's too much pressure.
Apply the solvent to the joint. I keep some 28 gauge insulin syringes handy. If you blow a bubble into the joint, you can scoop it out with the needle before pulling the pins (don't bother trying to suck it out with the syringe, just 'sweep' it to the edge) and continue applying solvent.
Depending on the length of the joint, solvent used, time taken to apply solvent, ambient temp & humidity, etc, you may need to start pulling pins right away after you're done.
Adjust joint as necessary to get alignment right. You don't have long to do this, maybe 15 seconds after you pull the last pin.
If it's a top or bottom joint, the first thing to do after you pull the pins is to check for drift. If your table is not 100% flat and level, then the whole thing will slide and you had better correct this right away, well before the joint starts to set.
If you have to hold the piece in place, you should only need to do so for about a minute, maybe 2 at most.
I put weight on when bonding the top and esp the bottom joints. I just lay strips of wood across the top and put whatever I have on top. Like this.
or this
Ok maybe not the soccer balls.
I use the non-ferrous metal blades as well, work perfectly.
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