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Clamping technique? Is this a thing? Question from a novice!

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Forum topic by Shaneswoodcuts posted 01-24-2018 06:51 PM 5116 views 0 times favorited 27 replies Add to Favorites Watch
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Shaneswoodcuts

15 posts in 146 days


01-24-2018 06:51 PM

Topic tags/keywords: clamping

This is my second day on LumberJocks – wow, am I blown away, overwhelmed actually… I’ve been trying to come up with one single question to get started knowing folks and people getting to know me! But, after seeing everything that was nearly impossible, until now. I just checked out a set of walnut table tops in the project section and noticed how he had things clamped up. I’m self taught, so when I see someone else doing something successfully (using steel clamped across sections to keep it level) that I’ve tried (unsuccessfully) then I know I’m on the right track. Which brings me to the question… Is there a proper clamping technique? I’ve pretty much used the brute strength technique – if glue isn’t oozing out everywhere, it must not be tight enough! It’ll be great to read your thoughts on this and if you want to share some trial and error experiences. Is there a “right” way?

-- Shane


27 replies so far

View Ripper70's profile

Ripper70

1020 posts in 931 days


#1 posted 01-24-2018 07:28 PM



... if glue isn t oozing out everywhere, it must not be tight enough!
- Shaneswoodcuts

Or, you’re not using a sufficient amount of glue.

-- "You know, I'm such a great driver, it's incomprehensible that they took my license away." --Vince Ricardo

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chrisstef

17422 posts in 3028 days


#2 posted 01-24-2018 07:38 PM

You can clamp it too tight and force all the glue out of the joint. When youre talking about steel or something across the top of the glued up piece they can be referred to as clamping cauls. Ill take a block plane and shave off a couple thou at each end so it acts like a spring joint then clamp down.

Welcome to the fray Shane.

-- Its not a crack, its a casting imperfection.

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LesB

1748 posts in 3465 days


#3 posted 01-24-2018 07:46 PM

There is a balance on tightness. Too much clamping pressure can squeeze out all the glue, especially on hard woods leaving a weak joining. Wood glue has a natural tendency to pull the wood together as it drys/cures. So squeeze out is a good indicator you have enough glue in the fitting but too much pressure is not always good. If the joints don’t fit together well when you dry fit them. Glue and a lot of pressure will not fix that. A good fitting joint needs enough pressure to push out the extra glue and hold the pieces until the glue sets up.
Normal wood glues are, Titebond II or III types, or hide glue (usually used heated).
Glue for poor fitting pieces would be epoxy (clamping only to hold together until it cures) or sometimes Urethane which expands as it cures so it needs moderate clamping pressure.
Temporary glues would be hot glue or small spot applications of CA (super glue).

-- Les B, Oregon

View John Smith's profile

John Smith

989 posts in 185 days


#4 posted 01-24-2018 09:04 PM

if you are using metal clamps, like steel bar or pipe clamps,
it is a good practice to put masking tape on the metal parts
that touch the glue areas – this prevents ugly black marks
on your wood joints that is difficult to remove.
it is not rust, it is a chemical reaction between the metal and glue into the wood.

-- Graduated Valedictorian from the University of HardKnocks --

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Tony_S

871 posts in 3105 days


#5 posted 01-24-2018 11:33 PM

You can’t squeeze all the glue out of a joint. It’s impossible.
In reference to PVA adhesives, you CAN over tighten to the point that you start to effect the strength of the bond(manufacturer’s specs), but never to the point that the glue joint will be weaker than the wood itself.
With that said, there’s no reason you should ever have to tighten a clamp to that degree with simple joinery. If it takes that much pressure to close a joint, you need better joinery techniques.
Tighten until the joint closes, no more.

-- It is the mark of an educated mind to be able to entertain a thought without accepting it. Aristotle

View Kelster58's profile

Kelster58

670 posts in 562 days


#6 posted 01-25-2018 12:44 AM

I find over tightening clamps distorts my project. I’m with Tony_S. “Tighten till the joint closes”.

Welcome to Lumberjocks. The people on this site are the best. Always sound advice. Always willing to help with advice. Rarely snarky. One of the few sites I can steer my students to and count on good results for them.

-- K. Stone “Tell me and I forget, teach me and I may remember, involve me and I learn.” ― Benjamin Franklin

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woodbutcherbynight

4820 posts in 2431 days


#7 posted 01-25-2018 01:48 AM



if you are using metal clamps, like steel bar or pipe clamps,
it is a good practice to put masking tape on the metal parts
that touch the glue areas – this prevents ugly black marks
on your wood joints that is difficult to remove.
it is not rust, it is a chemical reaction between the metal and glue into the wood.

- John Smith

Good tip, I would add wax paper can help with clean up and to keep two pieces of wood you do not want glued together from doing so. If a piece sticks rub it with a finger and it usually comes off, if not some sandpaper and all is good.

Welcome to LJ’s lots of cool ideas and very unique approaches to making all kinds of stuff. No shortage of imaginative projects here.

-- Live to tell the stories, they sound better that way.

View Fresch's profile

Fresch

243 posts in 1943 days


#8 posted 01-25-2018 01:57 AM


if you are using metal clamps, like steel bar or pipe clamps,
it is a good practice to put masking tape on the metal parts
that touch the glue areas – this prevents ugly black marks
on your wood joints that is difficult to remove.
it is not rust, it is a chemical reaction between the metal and glue into the wood.

- John Smith

Good tip, I would add wax paper can help with clean up and to keep two pieces of wood you do not want glued together from doing so. If a piece sticks rub it with a finger and it usually comes off, if not some sandpaper and all is good.

Welcome to LJ s lots of cool ideas and very unique approaches to making all kinds of stuff. No shortage of imaginative projects here.

- woodbutcherbynight

+1 on wax paper and yes many good people here, except him and him, he’s ok, like him, that guy there goof, you know like any place people will be people.

View jbay's profile

jbay

2332 posts in 921 days


#9 posted 01-25-2018 03:03 AM



You can t squeeze all the glue out of a joint. It s impossible.
In reference to PVA adhesives, you CAN over tighten to the point that you start to effect the strength of the bond(manufacturer s specs), but never to the point that the glue joint will be weaker than the wood itself.
With that said, there s no reason you should ever have to tighten a clamp to that degree with simple joinery. If it takes that much pressure to close a joint, you need better joinery techniques.
Tighten until the joint closes, no more.

- Tony_S


I agree,
It’s never happened to me in all my years.

View jerryminer's profile

jerryminer

926 posts in 1464 days


#10 posted 01-25-2018 05:52 AM


– if glue isn t oozing out everywhere, it must not be tight enough!
- Shaneswoodcuts

If it takes brute strength to close the joint, then the joinery is off and should be corrected.

As Tony said above, you can not starve a glue joint by over-tightening the clamps. That is a pervasive myth (which you can test yourself with scrap wood and your toughest clamps—and your biggest brute)

-- Jerry, making sawdust professionally since 1976

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Shaneswoodcuts

15 posts in 146 days


#11 posted 01-25-2018 01:37 PM

Thanks too everyone for the responses! I can tell now, this place is going to be an incredible resource! Wax Paper? I’d have never thought of that. I do glue stuff up on plexiglass (I hope none of you shivered when you read that). I can positively say that yes, my joinery sucks! Mainly because I’ve not yet ventured into cabinets, doors, boxes, etc. I’ve mostly done small projects, cutting boards, serving boards, tiny boxes (with dado cuts). I’ve read in other places in the forum, when you’re a beginner, start small and FINISH projects. So, at least I know I’ve done that much right. Thanks again for the valuable info!

-- Shane

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woodbutcherbynight

4820 posts in 2431 days


#12 posted 01-26-2018 04:32 AM

I might add you will NEVER have enough clamps no matter what size or type.

-- Live to tell the stories, they sound better that way.

View AxkMan's profile

AxkMan

65 posts in 148 days


#13 posted 01-26-2018 04:46 AM

The whole purpose of using clamps is to get the air bubbles out of the glue. This is what causes the tight bond. To test your glue joints, grip the work piece in your hand and try to snap them firmly to see if they come loose. If so, it is a bad glue joint.

I agree with you never have enough clamps. There are moments when the extra are needed in the middle of a job. Don’t forget art brushes to apply the glue. This is more useful in applying equal applications.

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Shaneswoodcuts

15 posts in 146 days


#14 posted 01-26-2018 01:03 PM



The whole purpose of using clamps is to get the air bubbles out of the glue. This is what causes the tight bond. To test your glue joints, grip the work piece in your hand and try to snap them firmly to see if they come loose. If so, it is a bad glue joint.

I agree with you never have enough clamps. There are moments when the extra are needed in the middle of a job. Don t forget art brushes to apply the glue. This is more useful in applying equal applications.

- AxkMan

Art brushes?? I do use the 2” disposable foam rollers you get from Lowe’s to make sure the glue is spread evenly. But, I do (for now, trying to really learn one thing at a time) mostly butcher blocks and small decorative kitchen stuff, haven’t really gotten into joinery yet, but that’s coming up soon. I’ve just been asked to make a set of custom drawer organizers. I can’t say no to anything, even if I have no clue how to do it.

Thanks to everyone for all of the great tips!

http://i50.photobucket.com/albums/f339/blowjazz/Mobile%20Uploads/IMG_20171204_170813628_zpsywtjgoch.jpg

-- Shane

View jerryminer's profile

jerryminer

926 posts in 1464 days


#15 posted 01-26-2018 05:15 PM

Shane—Your cutting boards look great, but you should be aware that you have glued-up a cross-grain situation and may have made boards that are destined to self-destruct. You are approaching the realm of the Panel of Doom
Read a little about wood movement. It is real, and should be provided for in anything made of wood..

-- Jerry, making sawdust professionally since 1976

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