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What did I do wrong? Face gluing

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Forum topic by ChiefDJ posted 07-03-2018 06:59 PM 924 views 0 times favorited 15 replies Add to Favorites Watch
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ChiefDJ

11 posts in 1341 days


07-03-2018 06:59 PM

So Im trying to glue a 5.5” x 12” 1/4” thick piece of maple to the same size piece of purpleheart face to face – resulting in a 1/2” thick piece.

I jointed and planed the faces and they dry fit together nicely. I used a generous amount (but didnt feel it was too much) of tightbond 3. I used clamps plus cinder blocks over 3/4 plywood to keep flat. Left for 30 hours.

The result was a nightmare. I wish I had taken pictures, but in no way were the boards flat. Despite the weight holding it down, the maple seemed to have warped and there were big 1/8” gaps between the boards in places.

Where did I go wrong?


15 replies so far

View DBDesigns's profile

DBDesigns

220 posts in 417 days


#1 posted 07-03-2018 07:15 PM

This is pure speculation but it sounds like maybe you used too much glue. I think it might be possible that before the glue bonded, the water content in the Tight Bond warped the maple and made it move differently than the purple heart. Was it soft maple? Was it completely dried before you glued it?

Maybe you should try hide glue next time since veneer gluing commonly uses it. Gorilla Glue might work as well but it requires that you moisten the surfaces so that might be counterproductive.

Also, I am interested in what project you are working on that requires this combination of materials.
Good luck.
Best,
Tim

-- I remember when Grateful wasn't Dead

View EarlS's profile

EarlS

2881 posts in 2768 days


#2 posted 07-03-2018 07:32 PM

My 2 cents worth – you didn’t have enough clamping pressure on the boards and/or there were openings between the clamps. When I glue thin boards together I clamp the entire surface as tightly as I can manage with clamps. I use HDMW spacers between the clamps and boards to make things easier to get apart after the glue is dried/cured. I would probably use a dozen or more Bessey Revo clamps on a board that is this size.

-- Earl "I'm a pessamist - generally that increases the chance that things will turn out better than expected"

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johnstoneb

3115 posts in 2592 days


#3 posted 07-03-2018 07:33 PM

I think your clamping method failed. Pictures would help.

-- Bruce, Boise, ID

View JADobson's profile

JADobson

1443 posts in 2530 days


#4 posted 07-03-2018 08:17 PM

It’s a pity this doesn’t happen every time someone tries to glue maple to purpleheart! ;)

-- No craft is very far from the line beyond which is magic. -- Lord Dunsany — Instagram @grailwoodworks

View Bill_Steele's profile

Bill_Steele

524 posts in 2151 days


#5 posted 07-03-2018 08:17 PM

It sounds like you did everything right—the result is baffling. Did the grain in both pieces run the same direction? How do you get clamps and cinder blocks on such a small glue up? If you’re going to do it again—I would suggest polyurethane glue and before applying it I would clean both surfaces to be glued with Acetone OR sand both.

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John Smith

1880 posts in 582 days


#6 posted 07-03-2018 08:20 PM

I don’t see how you can get clamps plus cinder blocks over the 3/4” plywood
on a piece of 5.5” x 12” 1/2” thick piece – - – unless the plywood was much larger
than the glue-up piece then the blocks were put on top of the plywood ?
and the clamps holding the edge of the plywood down too ?
I am thinking you may have somehow forced the glue into the center and trapped it there
when you sealed the edges with the clamps. sort of like a wet pocket in the middle
that did not dry completely. total mystery without some drawings, sketches or photos.
I’m with Johnstone.

-- I am a painter. That's what I do. I paint things --

View bondogaposis's profile

bondogaposis

5453 posts in 2771 days


#7 posted 07-03-2018 09:06 PM

I think the failure was due to too much glue and not enough even clamping pressure.You have to distribute the pressure evenly through out the surface. I don’t see how cinder blocks would be effective with clamps on such a small piece. A picture of your arrangement would be helpful.

-- Bondo Gaposis

View Woodknack's profile

Woodknack

12842 posts in 2800 days


#8 posted 07-03-2018 09:07 PM

Too much moisture/glue, insufficient clamping. Try using a glue that isn’t Water-based. Contact cement or polyurethane.


It s a pity this doesn t happen every time someone tries to glue maple to purpleheart! ;)

- JADobson


Lol, truly.

-- Rick M, http://thewoodknack.blogspot.com/

View Rich's profile

Rich

4564 posts in 1009 days


#9 posted 07-04-2018 01:40 AM

Purpleheart is among the tropical woods that are troublesome to glue up. A couple of tips that are often suggested are to sand the surface to roughen it and to wipe it down with a solvent like mineral spirits, naphtha or acetone to remove the excess oil that occurs naturally in the wood.

The previous posts that mentioned proper clamping are good suggestions to eliminate the warping it sounds like occurred.

-- Knowledge is not skill. Knowledge plus ten thousand times is skill. -- Shinichi Suzuki

View ChiefDJ's profile

ChiefDJ

11 posts in 1341 days


#10 posted 07-04-2018 02:18 AM

Here is what I’m trying to accomplish:

Maple + purpleheart are joined together and will be cut into right triangle strips with half maple / half purpleheart. These will be cut into little 1/8” tiles and put together in one of a number of neat patterns, which will go on top of a box I’m building.
The reason we’re using purpleheart is because that’s what she wanted and she gets what she wants. :)

The picture below is the pattern I’m trying to accomplish. Sorry it’s sideways:

And something like this is what Im ultimately working towards:

View ChiefDJ's profile

ChiefDJ

11 posts in 1341 days


#11 posted 07-04-2018 02:26 AM



I don t see how you can get clamps plus cinder blocks over the 3/4” plywood
on a piece of 5.5” x 12” 1/2” thick piece – - – unless the plywood was much larger
than the glue-up piece then the blocks were put on top of the plywood ?
and the clamps holding the edge of the plywood down too ?
I am thinking you may have somehow forced the glue into the center and trapped it there
when you sealed the edges with the clamps. sort of like a wet pocket in the middle
that did not dry completely. total mystery without some drawings, sketches or photos.
I m with Johnstone.

- John Smith

Sorry I didn’t make this clear.

I used plywood underneath and on top of the piece I was gluing together just to have a flat surface on both sides. I’m short on clamps so used the cinder block as weight over as much area as it would cover and clamped the rest down to the bench.

In hindsight the clamping wasn’t the best but it sure seemed to me there was a moisture issue. I just had never heard of others experiencing warping from the glue before.

View woodbutcherbynight's profile

woodbutcherbynight

5966 posts in 2828 days


#12 posted 07-04-2018 03:22 AM

Get more clamps, do not cheat on this portion of the project. Weight alone is not going to be sufficient. HF clamps are good enough to use, and cheap enough to not hurt the budget.

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

View joey502's profile

joey502

546 posts in 1937 days


#13 posted 07-04-2018 04:07 AM

I have noticed warping caused by what I though was the glue on thin pieces before. In my case they warped the entire piece warped, I did not have any issues at the glue line.

Since you have access to a jointer and planer I would suggest milling each piece thicker than 1/4’, gluing them up and then re mill both sides flat. Wait a couple days after the glue has dried before your final milling to allow the excess moisture get out of the wood. Offset the boards just enough to get an accurate measurement as you final mill. This will allow you to ensure each layer is of equal thickness maintaining the look you are going for.

When clamping pieces that thin I would use at least 2 layers of plywood on each side of the glue up to even out the clamping pressure. The plywood would ideally match the size of the parts being glued, maybe a little over sized. I keep scrap plywood around for this type of thing.

View 000's profile

000

2859 posts in 1319 days


#14 posted 07-04-2018 04:18 AM

View Kazooman's profile

Kazooman

1325 posts in 2372 days


#15 posted 07-04-2018 12:35 PM

Those pieces you are trying to make were more likely made as a long glue up that was then sliced into thin tiles.

Your comment “cut into little 1/8” tiles and then put together” sounds like a real challenge.

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