edge glue ups

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CrealBilly

New User
Jeff
I'm getting better results strength-wise edge gluing boards together to make up wide panels with my tablesaw than I do with my jointer. I know strange... but is true never the less... Seems the minor sawmarks left by the table saw actually help the glue to bond to something - I'm a big elmers fan and have tried titebond and don't like it as much. I'm left scratching my head, any suggestions would be most appreciated.

Thanks
 

FredP

Fred
Corporate Member
AK_CHOO_LIEE ya get a better bond that way BUT the joint is more visible. especially when you stain it. clear finishes not so much. I sometimes glue up right off the saw. depends on the wood and the project.:icon_thum
 

froglips

New User
Jim Campbell
Having just finished reading the Hide Glue book, I would hasten to say your strength observations are "scientifically" suspect.

Hide Glue does bond with wood in a different fashion than a PVA glue, such that it will work well when the wood has some "tooth". Much like the way plaster and lathe work. Hide glue does something called "adhesion" or, it bonds to itself. Which is why a toothed surface and hide glue work so well for veneering.

PVA glues do not have good adhesive properties (but do excel at cohesion). The more gaps between surfaces, the less wood to glue to wood bond you are actually making. (This is all based on what I think I learned, not from my homemade electron microscope......)

In my cartoon based mind, I see pva glue like a double sided carpet tape whereas hide glue is like stepping on someones discarded, warmed in the hot sun chewing gum with your deep tread hiking boots.

Maybe its worth further discussion as to why your jointer isn't giving you a good finished edge?

Jim
 

Travis Porter

Travis
Corporate Member
I would suspect the finish on the jointer isn't as good because the feed rate is too fast.

Fred came over way back and chastised me on how fast I was pushing the boards through. I have since upgraded to a shelix and the little valleys are now all gone.

One thing I do some when gluing up is to slide the boards back and forth a bit to get some "suction" going.
 

CrealBilly

New User
Jeff
One thing I do some when gluing up is to slide the boards back and forth a bit to get some "suction" going.

:eusa_thin nice tip, I'm gonna try that next time, maybe it's solve my issue. I think I may be tightening my clamps a little to much and might be squeezing out to much glue from the joint. The jointer is cutting fine, so I can't blame it... It's execution (me) :gar-La;
 

cpowell

New User
Chuck
Sounds like the jointer is set up good so it isn't sniping the ends. Do you alternate the faces you place against the jointer fence each time so if the fence isn't dead 90 (none are really) you still get a 180 degree joint when glued up?


Chuck
 

eyekode

New User
Salem
Jeff, how are you judging the strength of the bonds? Have you actually tried to break them? I have tried to break a simple edge joint before and it took much more effort (and leverage!) than I would have thought.

Enough so that if I broke two reasonably strong joints I am not sure I could tell which one took more effort (without setting up some sort of elaborate system based on torque: weight placed at a distance from the joint).

If it breaks easily I wonder if the joint is starved of glue?

Salem
 

Makinsawdust

New User
Robert
Jeff,
I think the reason your getting better results is because you have more surface area on the blade scored edge. Think about it as hills and valleys. Compression in clamping will hide a lot of roughness.
Rob
 

CrealBilly

New User
Jeff
Jeff, how are you judging the strength of the bonds? Have you actually tried to break them? I have tried to break a simple edge joint before and it took much more effort (and leverage!) than I would have thought.

Enough so that if I broke two reasonably strong joints I am not sure I could tell which one took more effort (without setting up some sort of elaborate system based on torque: weight placed at a distance from the joint).

If it breaks easily I wonder if the joint is starved of glue?

Salem

Usually by driving a screw into the joint (I try and avoid this but happens some times) I've had a few open up on me and it stinks to have to run it back through the TS and re-glue, you know? I don't have this concern when I glue up fresh off the TS.

Thanks
 
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