Thoughts about glue-ups and clamps

[Frederick Skelly]

A few weeks ago, I posted about how impressed I was with some new parallel clamps I finally tried. Since then, I've used them more and I'd like to compare notes with all of you on some of my observations about glue ups in general.

1. First, let me just eat some crow and say that our Pro's were, of course, right. There are certain times that, like it or not, you have to force a joint closed using more pressure than normal. It's not something I have to do often, but I had to get out the pipe clamps yesterday on the final section of that butcher block table. The JETs just wouldn't close the gap.

2. In my (hobbyist) shop, needing greater clamping force seems to happen when either I haven't done a dry fit to check how it all comes together, or I've fiddled with the wet glue-up until some of it is starting to set up. The partially dried glue has been known to "clog" the gap between two parts, rather like a shim. But if I properly fit my joints ahead of time, I don't seem to need a ton of pressure to get a rock solid glue up (on the things I build). Do you folks see the same - well fit joints need less pressure? Or is that just because I build small, simple stuff, rather than mahogany entry doors?

3. Parallel clamps won't correct small errors in un-square surfaces. What I mean, is that an F-clamp can swivel a degree or two and bring out of square parts together without leaving a gap. (You'll have to plane the mated boards flat again of course.) But if your parts aren't good and square, the parallel clamp will not create a tight joint - you'll have a thin gap filled with glue with wood touching wood only on one edge.

4. I'd forgotten how much I hate black pipe. Got crud from the pipe all over my workpiece because I forgot to wipe them down first (in the middle of that glue up). But man, can those stinkers apply force.

5. Glue gets stuck to parallel clamps. Not sure why it's more of a problem to remove than on F-clamps - the "tracks" look about the same to me - but dried glue does clog them. I wax the tracks and wipe them clean immediately after removing the glued up item. If it's stuck, I clean the track with a brass brush. How do you deal with this?

6. F-clamps are NOT the solution to everything, especially wide panels. They flex too much. (At least my 24" Jorgey's do.) I never snapped to that until recently. I'm finding that it works best for me to place 4 pipe clamps or parallel clamps on the work, then only use the F-clamps to fill in the gaps between. Even if the joint is fit right, the flex pulls the work out of plane. YMMV and yes, cauls can help with that. But it's so much easier using clamps that don't flex.

The Best Things has 10 Dubuque 24" clamps for about $210+shipping. I think I'm going to start saving up for a set. I've bought some old planes from there and enjoyed doing business with them.

7. For narrower glue ups, I really like the Bessey Revo Jr in an 18" length. Lightweight and effective. But again, I wouldn't go longer with the Juniors because of potential flex. I get out the JETs. But that's just me.

Any thoughts on my observations, or on glue ups in general?

Fred

[jack duren]

There's nothing wrong with galvanized pipe for glue ups. There was a time everyone was against it, but it works fine... you'll also find a time for a variety of clamps..

[Leo Graywacz]

95% of what I clamp up is by pipe clamps. I have some squeeze clamps and wood screw clamps for special operations, but the pipe clamp reins king in my shop.

http://www.fototime.com/D4ACACD19498845/medium800.jpg

http://www.fototime.com/2436671B791C4AE/orig.jpg

[Jim Andrew]

I use my parallel clamps for assembly. For gluing up panels, I have a few I beam clamps. If my panels fit right, I just use one I beam in the center, and use cauls on both edges, in a few inches, and if there is an offset on the ends, I use a c clamp to make it even. Cauls make a huge difference in the flatness of my panels, thanks to the forum for the information on using cauls.

[Greg Hines, MD]

I use the clamp that is needed, and I have a ton of them. Sometimes parallel clamps, sometimes Klik-clamps, sometimes F-style. It just depends on the situation.

Doc

[Steve Peterson]

Is the difference between parallel clamps and pipe clamps due to the handle design? Both clamps use a threaded rod with around 4-5 threads per inch. The parallel clamps only give you a 1" diameter handle. Pipe clamps have a 3" wide lever to be able to apply a lot of torque.

I have been thinking of getting a couple of Jorgensen I-beam clamps for the few cases where I need to really pull something together.

Steve

[Prashun Patel]

I recognize that parallel clamps provide more even pressure than do pipe clamps.

However (and I wonder if I'm the only one who has this issue), parallel clamps take a little trick to get them to engage. I often have to push the mechanism up while turning the handle or it won't engage and the I turn and turn and the threads just bottom out. I was teaching a beginner how to glue up a case last Friday and he had a devil of a time getting the Besseys to engage.

The pipe clamps, on the other hand, engage effortlessly. You know what you're going to get as you start turning. This makes long, panel glue ups much easier for me - especially with cauls where the increased cabinet clamp depth is moot.

I am about the messiest gluer-upper there is, and I never have issues with black pipe staining. It always planes, scrapes, or sands off pretty easily.

[Brad Barnhart]

I don't use anything but pipe clamps, & don't have any problems. I have a few harbor freight squeeze clamps, too, but they don't have enough pressure for a glue up. Some of my pipe clamps are on galvenized pipe, & others are on black pipe. I use a putty knife to clean the dried glue off the pipe. Placing the clamps is important. I put one on top & one on the bottom all the way across the glue up. I've always had good luck clamping this way. I plane & joint my face & edge joints to be glued. This insures a good flat surface to glue to.

[andy bessette]

The weight of pipe clamps can overwhelm a lightweight cabinet or frame unless it is possible to lay the clamps on the bench, jaws up, with the frame on top of them, in which case the frame need not support the heavy clamps. For my work I generally prefer Jorgensen Pony clamps or the lightweight aluminum bar clamps. If you fit properly excessive clamping pressure is unnecessary.

[Bill Dindner]

I think you summed it up pretty well, just want to make you aware of a great clamp, the Piher F style clamp, very deep reach and will not flex at all, and can give crazy pressure. I use them when I need to force a Domino joint together.

[Brad Barnhart]

most of the time my glue ups are laying flat on my work table, on the pipe clamps. I've found that equal pressure on both sides of the glue up gives a better glue up, & less pressure is needed if all sides & edged are jointed & faced.

[Frederick Skelly]

I think you summed it up pretty well, just want to make you aware of a great clamp, the Piher F style clamp, very deep reach and will not flex at all, and can give crazy pressure. I use them when I need to force a Domino joint together.

Thanks Bill. I hadn't seen these before.
Fred

[Arthur Fleming]

I am not even at complete newbie status yet. I am very close to Finally having made enough room in basement to start setting up a woodworking shop. Another flaw (LOL) for me is I am an electrician, tend to see things more from that side. I read a lot of these threads and try to learn as much as possible so that hopefully I can eliminate some of the upcoming trial and errors. After reading this thread a question I have is for pipe clamps, i have bought some of the pipe clamps and was planning on using aluminum rigid threaded conduit for the pipe. I can cut and thread as much of this as I want at work (See it's that electrician thinking). It seems from reading this thread that there are some negatives about using pipe other than black iron (which I can also rather easily get and thread, but it is much heavier) Any opinions on this might help me only cut and thread the proper type of pipe, the first time. I have found this forum to be like a school/teacher/mentor. Thanks for any input.

[Frederick Skelly]

Arthur,
I think that using conduit will give you too much flex in the clamp when you tighten it up. I'd go with black pipe over conduit and find a way to keep it from gunking up the parts you are gluing. Some have also mentioned using galvanized pipe successfully, but I haven't ttried that yet.

Good luck!
Fred

[glenn bradley]

I use the clamp that is needed, and I have a ton of them. Sometimes parallel clamps, sometimes Klik-clamps, sometimes F-style. It just depends on the situation.

Doc

That would be me :)

[Bob Michaels]

How about plastic shower curtain rod covers over the black pipe or spring for galvanized.

[jack duren]

There's nothing wrong with galvanized pipe..

[Larry Edgerton]

If you're having to force a joint closed that much, well......


Gee, I sure wish I was as talented as you

[Frederick Skelly]

There's nothing wrong with galvanized pipe..

Jack, you use actual pipe, not conduit, don't you?

[jack duren]

Never used conduit. It would be hard to imagine the treads holding up to maximum pressure.

[jack duren]

Gee, I sure wish I was as talented as you

I think there is a lot of confusion on what is enough and too much.

[Dennis McCullen]

The weight of pipe clamps can overwhelm a lightweight cabinet or frame unless it is possible to lay the clamps on the bench, jaws up, with the frame on top of them, in which case the frame need not support the heavy clamps. For my work I generally prefer Jorgensen Pony clamps or the lightweight aluminum bar clamps. If you fit properly excessive clamping pressure is unnecessary.

After purchasing a pipe clamp (using Al) from a thrift store, I outfitted a few other pipe clamps with Aluminum pipe. The "grips" eat into the Al pipe just a little but get good grip easily. If used daily, these Al pipes would need to be replaced in a couple years. I am an infrequent woodworker, so they'll last me a decade, at least. The lighter weight is very noticeable and iron pipe on the bottom clamps with Al pipe over the top might be a good answer when lots of pressure is needed. I have personally bought several Aluminum bar clamps (rectangular-shaped bars) in the past year. I bought them from the cheap Chinese tool store then outfitted them with an internal piece of wood (the Paul Sellers method). Additionally, I hot glued some thin 1/8" birch plywood to the jaws for a cushion. They work fine if the joint is already a good fit.

[Will Blick]

Some great advise here...
and thx too for the Piher clamp link, was not aware of this brand.

I agree that the amount of force required varies based on how well the edges are straight and flat...not always as easy as it sounds. And even when accomplished, within a few hours after jointing, wood can move quickly.

In theory, if the edges are perfectly flat and straight, no clamps are required, a rub fit will suffice. In the real world, nothing is that straight and flat. Titebond recommends up to 250psi at the joint line, that is a lot of pressure. This is not for the glue, but to asssure the edges touch each other and gaps are closed, this is what gives glue the highest strength bond.

For 1 inch thick material for simple math, 4 ft long boards, this is 48 sq in., or approx. 10K lbs of total force, max., at 200psi. How many clamps, depends on how much force each clamp can exert. I have tested a lot of parallel clamps, they vary greatly, from 500lbs to 1500lbs, such as the new Bessey and Yost tilt handles. With the Bessey, u must insert the rear hex with ratchet to go from 900lbs to the 1500 lbs, but it only requires 1/4 turn. Assuming 500 lb clamps, this is 20 clamps, one every 2.5 inches!! With 1500 lb clamps, its 7 clamps, one every 7 inches.

This might seem extreme, but the numbers fall quickly as not many use 1 inch material. using 1/2 inch material, you can cut the clamps in half. If your wood is freshly jointed and relatively straight, you can reduce clamp force down to 100psi, so cut the the clamps in half again, so only 1/4 the clamps above. So with 1500 lb clamps, 4ft boards, now only 2 clamps vs. 20 clamps! If its soft wood and well jointed, a single clamp and a caul will suffice.

This demonstrates just how critical the variables are when determining how many clamps to use. Eyeing the boards during dry fit, should give you a feel for psi required... if I see gaps, 200 psi, if boards look dead flat, 60 - 100 psi. For softwood, I use the low end, if wood is very hard, I use the higher end. This is why a single clamp with a caul is sometimes appropiate, and other times, clamps every few inches is appropiate.

BTW, if anyone is looking for bargain parallel clamps at max pressure, the BEST I ever tested are the discountinued Yellow STanley Bailey parallel clamps. 1500 psi with simple hand pressure, no tools. No other parallel clamp accomplished this except the Yost tilt handle heavy duty parallel clamp available on Amazon. Too bad Stanley stopped making them, I cherish the ones I have. they pop up used occassionaly. The worst of the ones I tested were Jorgensen and Pony, about 400 psi. So not all parallel clamps are created equal. Of course, this force is mostly only required for panel glue ups, most other tasks never require much force, so nearly any clamps that fits, will suffice.

Here is pix how I test the clamps. BTW, this test shows how clamps loose their pressure over time. This clamp went from 1k psi to less than half in 2hrs. So if you use longer setting glue, re tighten the clamps every couple of hours. A 1/8 of a turn can add 400 psi.
A lot of people ask me where I bought this gage, I bought it 14 years ago, I forgot !

423820

[andy bessette]

In real life the number of clamps required, and their position, is determined by watching the squeeze-out.

[jack duren]

In real life the number of clamps required, and their position, is determined by watching the squeeze-out.

Width,length.thickness all play a part of an assembly.

[Leo Graywacz]

On a 2 board glue up that is 36" long I use 4 clamps. Good to go. I'm not killing the screw with pressure. Failure is extremely rare, usually caused by low temps.

[Will Blick]

the more glue I apply the more squeeze out I get, I dont always uniformly apply the exact same amount of glue.
Speaking to a Titebond engineer at a trade show, he mentioned, its nearly impossible to starve the joint from glue, due to squeeze out. That was 10 yrs ago, and since then, I start applying clamps more methodically....

[jack duren]

This is the reason I don't have glue line nor so called glue creep. When someone says you can starve a joint on titebond I just move to the next post....

If you don have enough clamps you have to really think of how you will get good pressure across the joint. If you have enough, then use enough...

I'll use as many as I can get on there..

.423833

[Mel Fulks]

[QUOTE=jack duren;2983379]This is the reason I don't have glue line nor so called glue creep. When someone says you can starve a joint on titebond I just move to the next post....

Yep, the Titebond guys say they have NEVER seen a "glue starved joint".



.423833

[jack duren]

[QUOTE=jack duren;2983379]This is the reason I don't have glue line nor so called glue creep. When someone says you can starve a joint on titebond I just move to the next post....

Yep, the Titebond guys say they have NEVER seen a "glue starved joint".



.423833

Sorry I don't get pictures. You'll have to set up a link.

What would I be looking at ?

[Mel Fulks]

I use the clamp that is needed, and I have a ton of them. Sometimes parallel clamps, sometimes Klik-clamps, sometimes F-style. It just depends on the situation.

Dr. Hines, I'm guessing some of the fat people need the big strap clamps !

[Frederick Skelly]

Two weeks ago I struggled to clamp a chair I was repairing. It was an odd shape that really didnt fit any clamp or clamping jig that I could think up. I ended up using twine. (Of course, immediately after the repair had fully dried, I found a better way to clamp it - still using twine.)

A few days later, I ordered 25 ft of surgical tubing from Lee Valley. Odd shapes ahould be much easier next time around.

[Ron Citerone]

I use jorgy pipe clamps mostly for panel glue ups.

The BIGGEST improvement in my world has been learning proper jointer technique to get straight edges. But also, reversing the faces of boards as they come off the jointer fence.

One more thing. Clamp as soon after jointing before anything moves!

[andy bessette]

https://i.postimg.cc/XvxnyyHf/surf-4.jpg (https://postimages.org/)
https://i.postimg.cc/jj1D4Fhv/surf-8.jpg (https://postimages.org/)

[Leo Graywacz]

Hope that's plywood or other sheet good in the field. Nice job on the clamping.

[andy bessette]

Hope that's plywood or other sheet good in the field. Nice job on the clamping.

In case you're addressing me, yes, double layer of 3/4" teak plywood, with solid teak edging, splined with 1/4" Bruynzeel plywood, assembled in 2 glue-ups using WEST epoxy.

https://i.postimg.cc/cCPxLyDP/surf-2.jpg (https://postimages.org/)

[Leo Graywacz]

Yes I was. Glad to hear that too. Now it won't blow up on you. I've seen lots of tables made with wood surrounds that bust open their borders because of seasonal changes.

[Ron Citerone]

https://i.postimg.cc/XvxnyyHf/surf-4.jpg (https://postimages.org/)
https://i.postimg.cc/jj1D4Fhv/surf-8.jpg (https://postimages.org/)

That is intense clamping there! Thanks for sharing!

[jack duren]

In case you're addressing me, yes, double layer of 3/4" teak plywood, with solid teak edging, splined with 1/4" Bruynzeel plywood, assembled in 2 glue-ups using WEST epoxy.

https://i.postimg.cc/cCPxLyDP/surf-2.jpg (https://postimages.org/)

Glad it worked out. I made an 4×8 ebony table with a 8/4 maple edge with a radius on one edge. The first table built, shipped and got returned damage from the shipping company.. because of the return several weeks when by and rebuilt a second table. By this time original client bought a different table from the internet. The original table was paid for by the shipping company but the second table wax not. I hope they broke even with the shipping company reimbursements for the first table....

[Mel Fulks]

Yes I was. Glad to hear that too. Now it won't blow up on you. I've seen lots of tables made with wood surrounds that bust open their borders because of seasonal changes.
Yep. And sometimes the round corners can shrink and distort quickly after being cut out. I cut them a little long and put
them in a warm dry spot before final cut.

[Bill Carey]

I am not even at complete newbie status yet. I am very close to Finally having made enough room in basement to start setting up a woodworking shop. Another flaw (LOL) for me is I am an electrician, tend to see things more from that side. I read a lot of these threads and try to learn as much as possible so that hopefully I can eliminate some of the upcoming trial and errors. After reading this thread a question I have is for pipe clamps, i have bought some of the pipe clamps and was planning on using aluminum rigid threaded conduit for the pipe. I can cut and thread as much of this as I want at work (See it's that electrician thinking). It seems from reading this thread that there are some negatives about using pipe other than black iron (which I can also rather easily get and thread, but it is much heavier) Any opinions on this might help me only cut and thread the proper type of pipe, the first time. I have found this forum to be like a school/teacher/mentor. Thanks for any input.


I've found the 3/4" black pipe from Menards to be much smoother and cleaner than what I can get from HD, or other places. Just finished 3 panel glue ups and didn't need to wash my hands. Plus the clamps move more easily over the smooth pipe.

[Will Blick]

love that edge glue up!!
I always wanted to try that, but feared the movement of the edge pulling away from the stable top.

[andy bessette]

love that edge glue up!!
I always wanted to try that, but feared the movement of the edge pulling away from the stable top.

Never had a problem using WEST epoxy. The plywood edges must be coated over and over until they will accept no more saturation. Have used splines, biscuits and nothing but a butt joint. The hardest part is surfacing the edging flush to the veneer.

Another.

https://i.postimg.cc/Jn0c7kPT/cstar-table-1.jpg (https://postimages.org/)

[Will Blick]

OH wow Andy, that is beautiful too !!
Thx for added info. So pls explain why with such deep edging, and a stable top, the edging wont move away from the top at some point? We all know wood moves, but ply is relatively stable. Are you suggesting the Epoxy is so strong it tames the wood movement and prevents pulling way from the ply? Very curious about why this is not problematic. Its great to know it can be done, but any additional info would be helpful.
thx in advance for sharing your findings...

[andy bessette]

Will--thank you very much. I believe this construction is successful mainly because of the teak, which is oil rich and, as such perhaps is more stable during seasonal humidity changes. But also because of the finish that is applied (not shown--someone else applies that), which is a number of coats of WEST epoxy followed by varnish or clear polyurethane, which encapsulates the wood and provides UV protection. On the other hand the marine environment is one of the toughest of all.

[Will Blick]

ahhh, the epoxy finish... never tried that before, but makes perfect sense. I assume, if done right, the epoxy will prevent changes to the wood moisture level, elminating movement...of course, its still vulnerable to movement from extreme changes in temps. I notice more and more epoxy finishes, this is must be the reason! Thx for sharing...

[Larry Edgerton]

Will--thank you very much. I believe this construction is successful mainly because of the teak, which is oil rich and, as such perhaps is more stable during seasonal humidity changes. But also because of the finish that is applied (not shown--someone else applies that), which is a number of coats of WEST epoxy followed by varnish or clear polyurethane, which encapsulates the wood and provides UV protection. On the other hand the marine environment is one of the toughest of all.


I use that method on any projects that break the rules of conventional woodworking wisdom. In extreme cases I have pulled the West System further into the wood with a vacuum bag before final sizing of parts, assembled with West, Finished with West 207, and then a top coat of choice, usually automotive clear. Boat building is a wealth of knowledge right at our fingertips.

[Will Blick]

I was thinking of the same thing while this thread was developing, specially since West epoxy is so tied to the boating field of ww. I get their newsletter, and see some amazing glue ups. If they can make crazy shapes that hold up over time with extreme exposure to the elements, then it should be possible for fine ww as well. Of course we have a higher threshold, i.e. to prevent tiny gaps from forming in joints, whereas boat builders prob. not that anal! However, that level of finish you mention, to protect from small movements is something I never seen applied to fine ww. Did you learn these techniques from ww boating books, or from West Epoxy publications? I would be interested in learning more about this.

[Brian Holcombe]

I use a lot of clamps for glue ups. I did a lamination recently on a 50” long part.

424062424063

[andy bessette]

...Of course we have a higher threshold, i.e. to prevent tiny gaps from forming in joints, whereas boat builders prob. not that anal!... Did you learn these techniques from ww boating books, or from West Epoxy publications?...

This really made me laugh. :) Do you actually believe that clients who own multi-million-dollar yachts are less demanding of the quality of their woodwork? :) The table first shown in clamps I installed on a yacht worth perhaps $15,000,000. Other yacht clients include Larry Ellison (Oracle Systems), the Waltons (Walmart).

A good place for you to start learning about using (especially WEST) epoxy is the book: "The Gougeon Brothers on Boat Building". I have been using their products (literally barrels of epoxy) since the mid'70's.

Me working on 281' yacht "Aquila", the largest yacht to be built in USA since the 1930's.

https://i.postimg.cc/BZD9V2jk/IMG-1497.jpg (https://postimg.cc/nMHPsjYG)

[Will Blick]

My comment (the way I wrote it) did deserve a chuckle ;)
Of course, I agree with you...
When I wrote that, I had the pictures in my mind, of the West Epoxy newsletters, where they show many boat skeletons being glued up. These joints will never be seen as they are covered. A kitchen table as this thread was about, is viewed everyday. I was not thinking in terms of the finished areas of the boat.
That yacth in the background is insane!! That must be the 1/10th of 1% the population we hear on news ;). OK, in this case, .000000001%.... thx for the rescource, will check it out!

[Zachary Hoyt]

I have only built a couple of canoes, but based on my limited experience I would say I would be much more concerned about a crack or opening of any sort in my canoe than in a piece of furniture. Especially when I'm floating around in the canoe, since it would tend to let the water in which leads to unpleasant (and relatively immediate) consequences.

[Will Blick]

If a tiny joint opened, and let water in and your canoe sunk.... well, guess what?
EVERYONE is in full agreement with you Zachary! In this case, your tiny open joint is more critical then a cosmetic joint opening in a table top!!!

Of course, I was only referring to small tiny openings in the skeleton of a boat carcass, that never sees water. My entire point was, if boat builders can keep their joints tight, exposed to elements 2x worse than a kitchen table, then it makes sense there must be ways to secure edge molding from moving, in sizes and places where its not seen much in fine ww. Examples above in this thread.
Amazing the direction these threads can go!

[Larry Edgerton]

424081424082This table breaks all the rules, and ironically sits at a restaurant at a harbor in front of The DeVos family rowboat. Our secretary of education regularly dines here at this table, and no cracks even after a steam pipe broke in the restaurant at night. West for the win! There are others, but West has helped me every time I had an unusual project, they are the bomb, and to save a few dollars I would feel like I was cheating on my wife Ha!

[mark mcfarlane]

...

7. For narrower glue ups, I really like the Bessey Revo Jr in an 18" length. Lightweight and effective. But again, I wouldn't go longer with the Juniors because of potential flex. I get out the JETs. But that's just me.
...

I tend to reach for my short Revo Jr's first, due to their light weight. They seem to be able to provide enough pressure for the types of furniture I have been building and they weigh a lot less than the big Bessey's. At first I didn't like them, they just don't feel as hefty. Now I love them: they are good enough. I'm thinking off buying a few more 18"s.

If I have a joint that won't mate well due to movement after milling I recut it, at least on larger long grain glue ups where I have extra width. I've never had a gap in long glue ups freshly cut on my slider, which is one of the unanticipated blessings of having a long throw slider: very accurate straight edge rips.