Large-ish panel glue up

[David Wadstrup]

I'd love to take a poll on how you guys handle flattening boards that get glued up into large sized panels. Mine, in this case, will be about 40" x 24". Panels will be made up of 2 or 3 rough sawn boards apiece.

A) Do nothing, glue up, then flatten

B) Roughly flatten, glue up, then finish flattening

C) Flatten, then glue up(and cross your fingers you can get them glued up perfectly)

?????

I'm leaning towards option B myself. How would you approach this? And, if you feel strongly for one approach over another, why?

Thanks for our help.

David

[Shawn Pixley]

Flatten slightly over thickness, joint, glue-up using cauls, breadboard ends, then flatten / smooth with your smoothing plane. This assumes appropriately dried stock. I've done this many times. Works for me.

[Mark Dorman]

Plan B. Personally I do a 4 square that is just a tad ( whatever a tad is) over the desired finished dimension. Then when I do my glue up I use cauls like Mike Haulbrooks (I think that's were I saw them) and after that plane them down to the desired thickness.

[David Wadstrup]

That's 2 for plan B, so far. I don't own any cauls, but I did make a couple of panel clamps using these (http://www.leevalley.com/US/wood/page.aspx?p=31181&cat=1,43838).

[Michael Peet]

Plan B. Personally I do a 4 square that is just a tad ( whatever a tad is) over the desired finished dimension. Then when I do my glue up I use cauls like Mike Haulbrooks (I think that's were I saw them) and after that plane them down to the desired thickness.

Mike Henderson: http://www.sawmillcreek.org/showthread.php?126343-Tutorial-Shop-Made-Cauls&highlight=caul

I made some and have used them for panels. They work well. More narrower pieces might make a more stable panel than fewer wide ones.

Option B, arranged so the good planing direction is the same to reduce tearout. Although I do make an effort to get them pretty flat to start with and the thicknesses uniform. Combined with cauls you might be surprised at how little final flattening you need to do.

Mike

[David Wadstrup]

Michael,

The boards I have happen to be so wide that I'll only need 2 or 3 to meet the width of my finished panel. Would you recommend ripping these down and gluing them back up to achieve a more stable panel?

Thanks for your help.

David

[Mark Dorman]

Mike Henderson: http://www.sawmillcreek.org/showthread.php?126343-Tutorial-Shop-Made-Cauls&highlight=caul

I made some and have used them for panels. They work well. More narrower pieces might make a more stable panel than fewer wide ones.

Option B, arranged so the good planing direction is the same to reduce tearout. Although I do make an effort to get them pretty flat to start with and the thicknesses uniform. Combined with cauls you might be surprised at how little final flattening you need to do.

Mike
Thanks for the memory jog. Mike Henderson is where I learned about Cauls. They work.

[Sean Hughto]

Absolutely not. Use max widths of well prepped boards.

[David Weaver]

Plan B, match plane the edges and then clamp, and flatten after dry. If the boards are already relatively flat, then A.

[Chad Johnson]

I strive to get a perfect glue up and then flatten only if absolutely necessary. Lots of ways to glue up panels so you may need to experiment. I really struggled with this when I was first learning. I finally realized that edge gluing boards needed to be approached with the same level of particularity that I approach other forms of joinery. I get along best if I mill all my stock, and place the boards to be glued up on edge and stack them, if they are milled well they will balance on top of each other and let you dry fit the panel. I then run a straight edge along the boards that are stacked on edge to see if the edges match up flat or if I need to tweak so the edges all match up and rest on each other to form a flat panel. I am a fan of an ever so slight spring joint when gluing up panels. Many people may disagree and get good results without the spring joint, but I get along best with a spring joint. After I am happy with how the boards match up I place my glue and clamps. When you are careful with how your boards line up while dry fitting it does not require much clamping force at all. By minimizing clamping force you minimize the likelihood of introducing a cup when the board is in clamps. The above requires a lot of work at the beginning but usually results in flat panels straight from the clamps.

[Jim Belair]

B

Only if a board had a significant cup would I consider ripping it and gluing up.

[Prashun Patel]

I'm not sure what 'roughly flatten' means.

I flatten each board before glue-up, then try to glue it up perfectly using cauls or dominos or dowels, then reflatten (cross-grain) with a hand plane. The nice thing about large panels like that for tabletops is that they really don't have to be truly flat; they just have to be locally flat at connection points and flat enough to the naked eye.

I would not rip and reglue for stability. I do it sometimes to get stuff through a jointer or planer, or if I have planks of odd widths. I think grain match / aesthetics should trump everything - even if it means orienting the boards in different grain directions.

Even though it takes more time, on very wide glue ups with very narrow pieces, I like to glue up in 12" sections that can be flattened through the planer. Then i glue the 12" sections together. If you do it this way, I would not flatten the faces beforehand, but I would leave them oversized. If you plane and flip, you will get pretty flat

[Derek Cohen]

A smigeon under-or-over the planned panel thickness is not important at the end of the day. What is relevant is that the panels end up the same. I prepare all boards as close to the final thickness as I can so there is less to remove later.

What is most relevant is that the face and opposing sides of each board are square to one another. The plan is to flatten the back of the panel at the end of the glue up ..... or not - if the panel is a table top and will not be seen, then only the circumference needs to be coplanar.

http://www.inthewoodshop.com/Furniture/AShakerTableforMothersDay_html_73b8d1c5.jpg

If the face and opposing board sides are not square to one another, you will not be able to glue up the panel so that the panel face is flat/coplanar. What you will end up with is a banana.

http://www.inthewoodshop.com/Furniture/Kist_html_m334d2216.jpg

Regards from Perth

Derek

[David Wadstrup]

Thanks for sharing your opinions, everyone. So what I'll do is get them basically flat, glue up, then perfectly flat. These panels are actually for the case of a dresser that I'm building. I'm a little nervous how this project is all going to come together as I'll be hand planing all pieces to final thickness/getting them perfectly flat, AND THEN putting the case together using miter joints. Doing all of this in a day(before the pieces have a chance to start moving on me) will be a challenge(I'm a relatively new hand tool woodworker, and getting things perfect flat usually takes me A LOT of time.) Also, cutting and joining what will be 23" miter joints so perfectly that there will be no gaps, and everything goes together square. I think I'm going to use me Festool track saw to cut the miters. And either glue blocks or angle irons in the inside corners to strength the structurally weak miter joint.

I'd love to hear any advice you have that could help me with this project.


Thanks, again. Your input is really, really helpful.

[Sean Hughto]

If your design could stand blind dovetails, you wouldn't have to worry much about "perfectly flat" as the joints will be more than sufficient to pull everything in line.

[Prashun Patel]

Personally I wouldn't use miters. Not only are they tricky on long components that are perfectly flat, they're not particularly strong. I'd either do dovetails or pinned rabbets, or some kind of a locking rabbet.

[Curt Putnam]

Please don't use miters - especially for a large case piece like a dresser. If you want the mitered look then consider full blind dovetails, otherwise half or through DTs are to be preferred. Dowel pinned rabbet joints are attractive enough for me. If your design permits, moldings or veneers will conceal the joinery.

[David Wadstrup]

Believe me, I have sweated and sweater over this decision to go with miters. I know it's not the strong choice and probably not the wise choice. Design-wise, though, it is the choice I wanted to make. For a while I was considering going with full blind dovetails. But I figured that it would be even more difficult getting the miter part of the joint perfect than it would to make a full through miter joint. And that it would be just as strong if I ran a glue block the full span of the joint. I'd love to hear if anyone disagrees. If my assumptions are wrong, I'd really appreciate being set straight.

[Robert LaPlaca]

Getting a 24" wide miter joint to close up will not be for the faint of heart, plus as others have stated it will not be very strong.. Adding a full width glue block that is cross grain isn't a good idea either. If you are set on using a miter joint if you splined it, the spline would make the joint stonger, the spline wouldn't be cross grained and would make the glue up easier so the miter doesn't keep sliding around on you.. Even Domino's or biscuits might help you here..

[Sean Hughto]

If the miter look is only important on the face of the carcass, dovetails with a mitered end are the way to go.

[David Wadstrup]

It's mostly the sides that concern me. I'm going for a very sleek, lightweight, clean look, and front and sides will be visible. Good point on the full width glue block -- I overlooked how the grain orientation wouldn't work. I have some heavy duty right angle irons I could use. They're about 4" wide. Very sturdy, with no flex. I did think Dominos might be helpful, but ended up ruling them out. I feared that even they wouldn't be strong enough -- the thickness of my stock will end up at something like 3/4" which won't make for very deep Domino mortises.

[Jessica Pierce-LaRose]

If the front is important and you care less about the sides, you could easily attach a thin face frame, or use my favorite approach and mitre the front dovetail like the "Jefferson" stacking bookcases that have been in Popular Woodworking and the Woodwrights Shops.

(Video at PW explaining the single-miter dovetail joint:

http://www.popularwoodworking.com/woodworking-blogs/chris-schwarz-blog/video-mitered-shoulder-dovetail