Glue clamp jig?

[Smilodon]

Have anyone here ever made a glue clamp using bolts instead of using normal glue clamps?

I had this idea of making two beams from 2-3 layers of 12mm plywood where I drill pairs of holes about 8-10 cm apart for 8mm bolts. In my mind this will make the clamping pressure more even and more stable (as in less sliding around) and will also make cauls redundant.

The holes for the bolts probably need a bit of slack to allow it to clamp tapered neck blanks, but that shouldn't be much of a problem. Using long threaded rods it could even be adapted for blamping body wings to a neck beam. And maybe even a fretboard.

Am I crazy, or could this actually work?

My main motivation for making this is space, though. I live in an apartment with not much storage space. Glue clamps are suprisingly difficult to store.

[lbridenstine]

I have seen them, not sure if it was here or tdpri. It looks like it works.

[pilotjones]

I did pretty much exactly that. You can find my neck beam clamping jig in the storm king 1 thread.

[Smilodon]

Ah! I looked through your thread again and remembered that I had seen that jig before. I guess the idea was too good to not be new.

Were you satisfied with the jig, or is there anything i should keep in mind?

I was planning to add a sheet of 5mm acrylic glass or rubber sheets to the inside surfaces to prevent the glue from sticking. Maybe i'll make some sort of shield to protect the bolts from the glue as well.

I see a weekend of jig-making and drawing ahead of me. I may even start a new worklog.

[pilotjones]

Lessons/observations from mine, and thoughts on what you said above:
- I lined mine with wax paper to protect the clamping surfaces from glue. It worked, but it was a bit of a pain, one more thing to wrestle with while setting the jig, when you're concentrating on centering the neck down the center and then tightening all those bolts before the glue starts to set.
- Next time I will get an electric screwdriver and hook it up with a deep hex socket, to speed the initial tightening. Final torquing will still be with wrenches.
- I put teflon tape on the threads, in the area between the plates, to try and make it easy to release any glue. It worked about 75%.
- Both bolts and allthread are expensive in larger sizes.
- I used allthread and cut it into lengths. This is cheaper than bolts. It is also much more work to cut and end-chamfer the rods.
- Using allthread (or a bolt with an extra nut at the head side) gives you the ability to pre-set the effective thread length, so that when you do the clamping nut run-down, there is a minimum of thread to run it down on.
- I like your idea of using some rubber to line the cauls - probably silicone rubber would the best at shedding all glues. You might make it so that it the rubber starts at one edge of the working area of the bed, against the bolts, then across the bed, then has a few extra inches to run up the bolts on the other side to protect them. Then do the same thing on the top plate. If you did this you'd want to cut away the extra rubber between the bolts, both so that you have visual and manual access to the workpiece, and so that if you're using any conventional water-based glues, there is air circulation.
- As you said, you may need to open up the holes some to allow clamping a tapered stack. I'd start with the holes narrow, and widen them by degrees just enough to work.
- If you're clamping a tapered stack, you'll need to either pin/dowel it well, or find some other way to prevent layers squirting out. This can develop some impressive clamping force.

[Smilodon]

Thanks! I'll keep all those in mind.

I was thinking about making the rubber sheet into a U-shape that is stapled to the "top" of the jig. (Well, actually just below the top row of bolts.) That way I have a good "window" on top to see what I'm doing while the bolts at the bottom are protected. This way the rubber will never contact any other face than the two faces that are clamped.

And yeah, I will use locating pins when gluing. I usually do this even on flat pieces so that I don't have to waste time during the gluing process. On this particular neck the gluing will be done in several stages, and only the last stage will be tapered.

To torque the screws I was planning on using a battery powered drill that have a torque limiter. I'll just set it to a low setting at first and torque all the bolts progressively tighter to get even pressure. The drill I have now maxes out at 68nm. I'll test it out and see if that's enough.

[klyph]

I have lined clamps with HDPE, the waxy plastic that cutting boards are made from. It can be had for free from restaurants when they change theirs out. It can also be had cheaply from thrift or dollar stores. It works well, although it needs to be cut with power tools.