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Pipe Clamp Glue Ups

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Forum topic by MrHart posted 374 days ago 1194 views 1 time favorited 19 replies Add to Favorites Watch
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MrHart

41 posts in 782 days


374 days ago

Hi all,
I’m trying to find the secret to keeping your work flat while using pipe clamps for glue ups. Things always want to bow up or twist or get all kitty-wampus.
I am a sponge, you all are the liquid. I need to absorb some technique.

-- MrHart


19 replies so far

View Kaleb the Swede's profile

Kaleb the Swede

915 posts in 469 days


#1 posted 374 days ago

I’ve found using a dowel on either side works. It seems to equalize the clamping pressure. Sounds strange but it works

-- Just trying to build something beautiful

View Grandpa's profile

Grandpa

2981 posts in 1175 days


#2 posted 374 days ago

The cheaper clamp head don’t have a very tight tolerance. The hole for the pipe is too large on some and it allows the heads to tip back and start this action. A caul will help but you have to be careful to keep it from adhering to the boards you are glueing up. Try using 2 clamps on the end. Switch sides and put a couple on the other side. Snug these up slowly keeping everything straight as you go. Half the clamps on each side of your glue up.

View kdc68's profile

kdc68

1694 posts in 776 days


#3 posted 374 days ago

Alternate your clamps back and forth from underneath to on top.

-- Measure "at least" twice and cut once

View RogerInColorado's profile

RogerInColorado

270 posts in 454 days


#4 posted 374 days ago

Kaleb’s suggestion about the dowels is good. Put the dowels in the CENTER of the edges of the outer boards. The idea is to “equalize” or balance the pressure of the clamps so that the pressure is neither on the top edge or the bottom edge.

Another challenge is for the joined edges, if they aren’t dead perpendicular to the faces, to at least complement each other so they don’t bow as part of the natural order of things. If you’ve seen videos or reverences to planning boards two at a time to offset any bevel, this is the reason for doing that. (If you haven’t, don’t over analyze this comment).

View RussellAP's profile

RussellAP

2895 posts in 786 days


#5 posted 374 days ago

When I do large glue ups I clamp them flat first then clamp them together. A couple or three good 8/4 planed walnut does the trick with a good hold down clamp at either end top and bottom. After you clamp the boards together then tighten the clamps holding the work flat. Use film wrap to keep the glue from sticking to the hold flat boards.

-- A positive attitude will take you much further than positive thinking ever will.

View pintodeluxe's profile

pintodeluxe

3025 posts in 1313 days


#6 posted 374 days ago

I have a system that will give you dead flat panels without much effort.
1. Joint the edges with the “I” and “O” method. http://lumberjocks.com/pintodeluxe/blog/33797
2. Use clamps top and bottom.
3. Wide panels are glued up in phases. For instance when gluing up a 20” panel from 1×6 stock, glue up two pairs of planks first. Run those planks through the planer, and then do the final panel glueup.
4. Clamp a caul across the panel to keep it flat.

-- Willie, Washington "If You Choose Not To Decide, You Still Have Made a Choice" - Rush

View Loren's profile

Loren

6742 posts in 2147 days


#7 posted 374 days ago

Pipe clamp saddles help keep the heads accurately aligned. You
still have to alternate the sides.

If your clamps need to bow to close your joints, your joints
aren’t accurate enough.

View bluekingfisher's profile

bluekingfisher

957 posts in 1479 days


#8 posted 374 days ago

All of the above is usefull information, only if your jointed edges are true and square of course, any deviation from square will start the boards in your panel racking.

Don’t overlook the obvious, get yourself a good engineers square and use it to make sure the boards edge (both edges of every board) is square to its face. The basis of all good construction work is to ensure square and level, without these basic principles you will always end up with warped panels.

Good luck

-- No one plans to fail, they just, just fail to plan

View camps764's profile

camps764

662 posts in 859 days


#9 posted 374 days ago

all of the above are great suggestions.

I would echo BlueKingFisher as well – because I’ve been there as well.

Always thought I needed a new clamping technique – better cauls, better clamps, alternate clamping direction, etc.

All of the above are very important…but the biggest helper of all was learning to joint the edges so that they are truly square.

If you don’t have a jointer in your shop and don’t have the funds for one – get your hands on a good jointer plane or rig up a jig for your table saw/router table for edge jointing. A 90 degree face will solve most of the problem.

-- Steve

View Gerald Thompson's profile

Gerald Thompson

303 posts in 734 days


#10 posted 374 days ago

I made these clamping cauls and they have been a God send.

http://www.wkfinetools.com/contrib/hendersonM/makingCauls/makingCauls-1.asp

-- Jerry

View gfadvm's profile (online now)

gfadvm

9532 posts in 1189 days


#11 posted 373 days ago

Thanks Jerry- great technique on that link

-- " I'll try to be nicer, if you'll try to be smarter" gfadvm

View RussellAP's profile

RussellAP

2895 posts in 786 days


#12 posted 373 days ago

I think the jointer idea pays off the best. The clamp issue of having 30-50$ clamps is just ridiculous for most of us who have 70+ clamps. I make the F style HF clamps work for me and supplement with some pipe clamps. I still say that holding the boards flat with a couple 8/4 film wrapped boards is the best way to insure a flat glue up. I wish I had a machine press for it. But hey, there is nothing quite as -fun- as doing glue-ups is there? You can practice herding cats till you’re good at that, then clamping seems like a breeze.

-- A positive attitude will take you much further than positive thinking ever will.

View Loren's profile

Loren

6742 posts in 2147 days


#13 posted 373 days ago

In woodworking, preparation is everything.

Figuratively true of course, not literally.

View Lee Barker's profile

Lee Barker

2159 posts in 1350 days


#14 posted 373 days ago

I do a fair amount of glueups and I just don’t have a problem with bowing. I do not use cauls, dowels, or alternated clamps.

1. My jointer is dead accurate. I don’t need to alternate cuts. I joint by grain direction only.

2. I have Jorgensen clamps.

3. I center the work on the clamp feet (both ends). The work does not touch the pipes.

4. (And this has not yet been mentioned here) I don’t overtighten my clamps.

I feel as if this sounds arrogant, but I don’t mean it to. I want to make the point that it is possible to do it successfully without a lot of peripheral equipment.

Kindly,

Lee

-- "...in his brain, which is as dry as the remainder biscuit after a voyage, he hath strange places cramm'd with observation, the which he vents in mangled forms." --Shakespeare, "As You Like It"

View Dallas's profile

Dallas

2675 posts in 986 days


#15 posted 373 days ago

-- Improvise.... Adapt...... Overcome!

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