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

by Shaneswoodcuts
posted 01-24-2018 06:51 PM


27 replies so far

View Ripper70's profile

Ripper70

1263 posts in 1270 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

View chrisstef's profile

chrisstef

17893 posts in 3368 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.

View LesB's profile

LesB

2075 posts in 3804 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

1797 posts in 524 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.

-- Failure is proof that you at least tried ~ now, go do it again, and again, until you get it right --

View Tony_S's profile

Tony_S

967 posts in 3444 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 (online now)

Kelster58

748 posts in 901 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

View woodbutcherbynight's profile

woodbutcherbynight

5964 posts in 2770 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

424 posts in 2282 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 000's profile

000

2859 posts in 1261 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

951 posts in 1803 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

View Shaneswoodcuts's profile

Shaneswoodcuts

15 posts in 486 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

View woodbutcherbynight's profile

woodbutcherbynight

5964 posts in 2770 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 488 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.

View Shaneswoodcuts's profile

Shaneswoodcuts

15 posts in 486 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

951 posts in 1803 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

View Shaneswoodcuts's profile

Shaneswoodcuts

15 posts in 486 days


#16 posted 01-26-2018 08:38 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..

- jerryminer

Jerry, thanks for the link! I read it from top to bottom. And as a rookie, no, it’s not something I’ve thought of, even though I’ve repaired doors in my home due to the same thing… You’d think I’d have made the connection! Sometimes my excitement of doing this outweighs me taking a minute to use common sense like that… So, question… in this situation, would a biscuit joiner help? I didn’t use one on the two boards I posted the link for, but I have used biscuits in others to solidify them.

I need to share this place with some of my other wood working friends. The info, freely given, on here is invaluable! My wife says this is my new Facebook!!!

-- Shane

View jerryminer's profile

jerryminer

951 posts in 1803 days


#17 posted 01-27-2018 01:33 AM


would a biscuit joiner help?
- Shaneswoodcuts

Yes and no. A biscuit joiner will make cross-grain joints stronger (and help with alignment), but it won’t stop wood movement.

End-grain-to-long-grain joints are inherently weak, so biscuits (or other forms of splines/tenons) can help to strengthen a cross-grain joint. But when the size of the joint (i.e. width of the joined parts) gets too large, and the piece is in a place where the humidity changes, then wood movement can wreak havoc—which can show up as a crack in the piece, a failed joint, or other mayhem.

If your boards don’t see humidity changes, they will be OK, but in most places the humidity fluctuates and wood movement results.

I suggest—again—that you do some reading on wood movement so you understand how to design your projects to allow for it. Just as designers of steel bridges have to allow for the expansion of steel when the temperature rises, we woodworkers have to allow for wood movement when we design wood projects.

-- Jerry, making sawdust professionally since 1976

View woodbutcherbynight's profile

woodbutcherbynight

5964 posts in 2770 days


#18 posted 01-27-2018 04:45 AM

HF has a 36 pack of small 3/8 wide brushed, think they are called acid brushes. Work great for small jobs spreading glue and can be reused if you clean when you are done. OR hit ebay and buy 100 at a time.

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

View Shaneswoodcuts's profile

Shaneswoodcuts

15 posts in 486 days


#19 posted 01-27-2018 04:05 PM


I suggest—again—that you do some reading on wood movement so you understand how to design your projects to allow for it. Just as designers of steel bridges have to allow for the expansion of steel when the temperature rises, we woodworkers have to allow for wood movement when we design wood projects.

- jerryminer

I’m heading to woodcraft today to pick up some things, will see if they have books on wood movement or see what they suggest! Thanks so much!

-- Shane

View Tony_S's profile

Tony_S

967 posts in 3444 days


#20 posted 01-28-2018 12:08 AM


I m heading to woodcraft today to pick up some things, will see if they have books on wood movement or see what they suggest! Thanks so much!

- Shaneswoodcuts

Check out “Understanding Wood” By Bruce Hoadley
One of the best books out there.

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

View GrantA's profile

GrantA

1481 posts in 1769 days


#21 posted 02-27-2018 01:02 PM

I’ll add to the glue brush suggestion. The small acid brushes are great for small places but where you can use a wider brush I love my little silicone brush. Mine came from a big box store, it’s titebond branded but I know rocker and others have silicone bristle brushes. Just let the glue dry and it will pop /peel right out

View LittleShaver's profile

LittleShaver

527 posts in 981 days


#22 posted 02-27-2018 01:22 PM

I always keep a supply of acid brushes on hand for small glue ups. I find them a little too flexible so I usually cut the bristles back to about 1/2” long.
Another thing I keep handy for larger glue ups is a supply of motel key cards. They work well as pint sized trowels for spreading out glue. I haven’t tried it, but you could notch the edge with a pair of scissors for a real trowel effect.
Welcome to woodworking. You’ll find there are many ways of doing just about everything and each method is backed by strong opinions. Choose what works for you and keep making sawdust.

-- Sawdust Maker

View AlmostRetired's profile

AlmostRetired

220 posts in 1076 days


#23 posted 02-27-2018 01:33 PM

Shane

Welcome to the party….use caution how often you visit…lol…there is a new item added to my to-do list daily around here.

Roger

View bandit571's profile (online now)

bandit571

22762 posts in 3045 days


#24 posted 02-27-2018 02:40 PM

There is one other tip to try
Spread a bead of glue along one edge. Bring the next edge to the glue. press into the glue, then move the second edge back and forth along the length of the joint….you will feel it “stick”. make sure the two are aligned where you want them…they WILL sit there as if clamped up. Then you just add clamps as needed, until a bead barely shows.

I do a dry fit first, looking for gaps..

Then a “Wet Fit” glue in the joints, using the tip above…..only the glue holds these three boards in place.

Then add a few clamps, until a bead just start to show. Panels, I’ll add a few cauls to keep things flat, until the glue cures.

-- A Planer? I'M the planer, this is what I use

View Gene Howe's profile

Gene Howe

11494 posts in 3790 days


#25 posted 02-27-2018 03:04 PM

The plastic brush like applicators and acid brushes are great tools for smaller jobs. For a bit larger ones, as little shaver suggests, motel key cards and old credit cards are handy. I use the wife’s pinking shears to get the trowel effect. For even bigger glue jobs like large bowl blanks, those plastic Bondo applicators work well. Mine get the pinking shears treatment, also.

When using metal clamps that may contact the glue joint, waxing them helps. The glue will easily pop off the waxed metal and the wax will inhibit staining, also.

For removing squeeze out, let it dry and use a scraper to remove it. I like Bahco 625 carbide scrapers.
Wiping wet glue is a recipe for disaster. Becomes evident when finish is applied.

-- Gene 'The true soldier fights not because he hates what is in front of him, but because he loves what is behind him.' G. K. Chesterton

View MrRon's profile

MrRon

5439 posts in 3605 days


#26 posted 02-27-2018 05:03 PM

Check out this wood handbook. It will tell you everything you need to know about different woods. http://www.woodweb.com/knowledge_base/Wood_Handbook.html

View Thalweg's profile

Thalweg

103 posts in 3767 days


#27 posted 02-27-2018 06:23 PM

I’ve learned to completely clamp everything up dry before using any glue. That helps identify any problem spots that may need more attention. It also gets all of the clamps set to the proper dimension so I don’t have to mess around with it when I’m worried about glue setting up too quickly.

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