Leaseman

I Can Not Get A Flat Glue Up Ever

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Maybe you folks can give me some advice but no matter what I do I can never seem to get a completely flat glue up when doing a panel. I always have gaps, etc. Here is my process:

1) Run one face and one edge through my jointer

2) With the jointed edge against the fence of my table saw (and jointed face down) I square up the other edge

3) I then run the opposite face through the planer.

The individual boards come out flat but my problem is when I do my glue up.

Here's my process for glue up:

1) After gluing up the edge of the boards (using dowels to help line them up) I put them between three or four pipe clamps

2) With the two outermost clamps at the very ends of the boards I clamp the boards to the pipe clamps at the joints to keep them flat

3) I then take two or three clamps and clamp from the top

I'm doing something wrong here because my glued up boards (in this case pine) is not completely flat.

What is y'all's experience"

 

IMG_0536.jpg

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I think that most pine panels I've glued up have bowed at least a little.  The pine that I use is all plantation grown so it's probably not the most stable timber.

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I would hazard a guess that you have a few things working against you.

First. Pine. Notoriously unstable and expand and contracts a lot with humidity. 

Second, clamping placement and pressure. A lot of people clamp way too tightly. They need to be snug, and somewhat tight, but not super As-Tight-as-you-can-tighten tight. As to placement, I think someone else mentioned this too, you should have pipe clamps on top and bottom of the panel, evenly spaced.

Third. How is the blade on your table saw? If you're seeing gaps in your glue line you might need a better ripping blade (I know that's not what you showed in your picture but I thought it worth mentioning.)

Fourth. Expectations. Most glued up panels are not 100% dead flat, nor are most table tops. While I agree that you probably want to improve upon what your picture shows, ask yourself what your flatness expectations are and how much imperfection your willing to tolerate.

Fifth. You can try a panel clamp. Rockler sells a very nice one. 

One suggestion - get some quarter or rift sawn hardwood and glue that up, I think you'll be surprised at the difference. 

 

Best of luck

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7 minutes ago, applejackson said:

Third. How is the blade on your table saw? If you're seeing gaps in your glue line you might need a better ripping blade (I know that's not what you showed in your picture but I thought it worth mentioning.)

Good point.

I very rarely count on my sawn edge as a good edge for glue up.  After I trim it on the saw I pass that edge over the jointer to give me a super clean edge, this can really reduce the amount of clamp pressure needed.

Lots of good points from gee-dub and applejackson.

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Before you apply the clamps, if you lay the boards on a flat surface, how do the joints look? Are they tight and consistent just by sliding the boards together? Then flip them over and do the same thing. 

How do you drill the holes for dowels? If you do a dry assembly with dowels, are the joints still tight and consistent (same as they were without dowels)?

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I generally agree with all suggestions above. However, I would change your process slightly. I believe you should joint the first face and then use the planer to get the other face parallel before jointing the edges. Then, when you joint the edges, particularly the ones that are going to be glued, alternate faces against the fence/away from the fence. This will compensate for any slight out of square you might get holding the workpiece against the fence. Also, I'm concerned about the use of dowels to align the glue joints. Not that dowels are bad. Just that if the dowels are large enough and long enough and if they are not inserted perfectly true, they could be keeping the boards from going together flat. In a glueup like this, dowels are not needed for strength. IMO, biscuits would be adequate for alignment. Dowels are fine for alignment if they are small and short. Slight concern, I know. Also, I agree with the above that you should alternate the pipe clamps top and bottom. It also might help to clamp some straight cauls top and bottom to keep everything flat and then make sure that as you tighten the pipe clamps they don't force everything out of flat.

One additional comment about jointing. I don't think that depending on your table saw to properly joint an edge is a good thing. Most of the time, if you are making a table top, etc, your boards are going to be longer than your saw fence. Any curve in the edge registered to the fence will get partially duplicated on the ripped edge. Ok to start on the saw, but finishing up the jointing process on the jointer is a better practice. I'm not saying that it can't be done, Just that the jointer will give good results more easily. I know there are many that do it on the saw all the time. Just be aware that if your board is longer than the fence it is possible that your cut might not end up straight.

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I will point out that when using pipe clamps, it is usually not desirable for tge wood to touch the pipe. Black iron pipe, certainly, will stain the wood in no time. Even galvanized pipe can cause discoloration.

Of you make a lot of panels in similar sizes, consider a gluing rack of PVC pipe. 3 sticks a bit longer than panel width, some elbows, short pieces, and flanges is all it takes. Lay the boards ro be glued across the pvc pipe, and you can easily apply your pipe clamps above and below the panel to provide even pressure. Pipe clamps are easy to over do, so go easy on the screw!

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One more thing, and @Wimayo suggested it but I'd suggest ditching the dowels completely. They're unnecessary imo. Most yellow wood glue (like titebond) gives a bond when properly prepared that is stronger than the wood it is binding together. So if you were to glue up a panel and smash it face first on the edge of a cast iron table for instance, it won't the glue bond that breaks. It will be the wood. Try a glue up without dowels. If you still have the same problem you can rule them out as the culprit. One other thing that Wimayo said that I'll second is that a the jointer will usually give you a better glue line than your table saw blade will. Some premium blades do a great job (I use a Freud ultimate glue line ripping blade) but he's absolutely right that the jointer will typically give you the cleanest join.

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Good and valid ideas above. One more. In clamping bring the pressure in slowly. I start with bottom clamps in the center and screw until the joint barely touches, not real tight. Then add the top clamps slowly. And little by little tighten the screws, top and bottom evenly. If you put full pressure on the bottom clamps before you added the top clamps could cause problems. 

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Run the table saw edge on your jointer. Mark the face that is against the jointer for each edge of the board. Make sure that the edges alternate fence side up and fence side down. This takes any out of squareness from your jointer and cancels it (see the red mspaint drawing below). Also when you have perfectly jointed edges you don't need to apply as much clamping pressure. I included an image below from my coffee table build that illustrated this. This flipping strategy works for any and all edge jointing methods on machines eg table saw jointer planer router table. Each one will never be able to be perfectly square don't sweat it just work around it.

776927595_CoffeeTable014Share.jpg.66d5c2438fc5eec7df035c40fc2baff0.thumb.jpg.dda2dab986fd3e36df0a60e6f87263b9.jpg

The above about clamping strategies holds but having a clean edge that will allow you to get a good joint with little pressure negates a lot of the clamping issues. The top pictured above was clamped with 3 parallel clamps it's 50" long and 32" wide. I've done longer and wider with 3 clamps. I don't even think that it's glued in the picture just pushed together with hand pressure.

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For those of us without jointers, I've used the match planing method successfully to get a flat glue up. I find it helps to make them as seamless as possible, too. It's definitely a better edge than directly off the table saw.

See here for what I'm talking about, using a hand plane:

https://logancabinetshoppe.wordpress.com/2008/09/10/edge-jointing-the-match-planing-method/

 

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I think the thing I'm most guilty of is putting to much pressure on the clamps. I tend to really tighten them. Based on what your guys are saying I'm doing too much. Lots of other great insights here. I have two more panels to glue up for this project. I'm going to use some of the ideas here and post the results.

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11 minutes ago, SawDustB said:

For those of us without jointers, I've used the match planing method successfully to get a flat glue up. I find it helps to make them as seamless as possible, too. It's definitely a better edge than directly off the table saw.

See here for what I'm talking about, using a hand plane:

https://logancabinetshoppe.wordpress.com/2008/09/10/edge-jointing-the-match-planing-method/

 

Done this many times works great. Same method as on a mechanical machine just have to do them at the same time. I assumed he wasn't doing this by hand when he said he runs the material through the Jointer.

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2 hours ago, Leaseman said:

I think the thing I'm most guilty of is putting to much pressure on the clamps. I tend to really tighten them. Based on what your guys are saying I'm doing too much. Lots of other great insights here. I have two more panels to glue up for this project. I'm going to use some of the ideas here and post the results.

Clamps can win every time.

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3 hours ago, Chestnut said:

Done this many times works great. Same method as on a mechanical machine just have to do them at the same time. I assumed he wasn't doing this by hand when he said he runs the material through the Jointer.

No hand planning just using the jointer and planner. I have done the second of three panels for this project and it has turned out a little better. I think I was clamping it to hard. Also I'm going to look into getting the Rockler panel clamps mentioned by Applejackson. I'm finding that most of my "unflatness" tends to be away from the edges of the boards where I have the panel clamped to the clamps. The Rockler clamps would help with this. See below for a picture how I clamped this up.

IMG_0537.jpg.f50b82f175831e7fc3f09426348d1813.jpg

IMG_0538.jpg

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I am sure you got lots of good advice above. My first thought was "well it's pine, that's how it goes." 

I had a lot of trouble as well when I first started. Very gappy panels. Mostly it was my table saw. Nothing a few grand didn't solve. I'd still say 40% of my problem was inexperience and technique. I was marveling at how things have changed earlier today when I glued up a panel of 4 pieces of 1/4" thick cedar and they came out pretty flat. Man 2 years ago that would have been a disaster. I mean I still trimmed 3 panels an inch short in each direction because I'm an idiot and had to remake them - so I guess it's always a work in progress. 

 

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Another possibility. When dressing the face on the jointer, if the board is bowed do not put down pressure and flatten the bow...

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Have you tried using cauls? You can buy some, but I find a nice piece of scrap long enough to span the panel works just fine. I use 4 - 2 on top, 2 on the bottom - covered in packing tape so they don't get glued to the panel. A light tap with a hammer will release them if they do stick.

Clamp them so they keep the panel flat before you tighten your bar clamps. As others have suggested, don't apply too much force on the bar clamps. You don't want all of your glue to squeeze out.

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