flattening a joined tabletop

yieldmap | Posted in Joinery on April 20, 2004 08:46am

Hi all. First time on the forum, and I need a little help.

I’ve been building some small nesting tables for my family, and another set for a wedding gift. One problem I have is the slight “ridge” between the joined boards. No matter how careful I am when using the joiner and biscuit cutter, I always seem to get the boards out of plane with each other when joining. How do the pro’s achieve that perfectly “flat” tabletop?

Just for fun, I’m making the tables out of White Oak, Walnut, and Cherry (from small to large in the pictures) I’ve never worked with Walnut or Cherry before, so this is an experiment to see how well the wife likes these woods. The White Oak was salvaged from my dad’s farm. It’s been sitting on a hayrack (not stickered) for 10 years. He was burning it, and making jack blocks for the farm out of it…not any more.

Thanks,

yieldmap

Replies

Crunk | Apr 20, 2004 08:54pm | #1
Leave the pieces slightly over thickness (weak 16th if the individual pieces are machine jointed and planed) when you glue them up. After the glue has thoroughly cured, handplane the top flat or power sand the top flat.

Edited 4/21/2004 12:54 pm ET by BossCrunk
Elcoholic | Apr 20, 2004 10:50pm | #2
For purposes of clarification I'll call your condition a "step" from misalignment. It's very difficult to get a dead flat glueup and probably counterproductive to even try. Without getting into the whole bisquits do or don't have a place in an edge joint thing, a misaligned BJ or poor technique can yield poorer results than no bisquits at all. If you're getting a ridge (two slopes rising to a point) then that's due to cupping of the stock.

John O'Connell - JKO Handcrafted Woodworking

Life is tough. It's tougher if you're stupid - John Wayne

yieldmap | Apr 21, 2004 02:13am | #3
John,

Not really a ridge between two boards from cupping - they're good and flat. If they're cupped, I rip 'em, square 'em, and re-join 'em.

I use a caul and clamps on the outsides of the joint, and can get the sides perfectly flat. It's just the centers will move upward a little every now and then. It's not on every joint, but probably 1 out of 3. I suppose if I had some clamps with 12" throat, I could put another caul in the center and do the same thing.

I had a friend tell me the way pro shops do it is with a wide drum sander. But, I'm not looking to spend $1000 on a big drum sander.

I might try a dry fit, then mark the areas where the ledge is and hand-plane it flat. Then glue up and hope for the best!

Here's a couple more pictures of the final product. I finished the last coat tonight (1 coat of Danish Oil, plus 2 coats Wipe-on Poly on the top for protection).

Thanks,

yieldmap

Elcoholic | Apr 21, 2004 04:15am | #5
I think you're short a zero on the cost of a wide belt. On big table tops I go to a cabinet shop about 15 min away and use their 48" widebelt. They have a $25/15 min and I've never gone over the min. On smaller stuff I use my Bosch 4 x 24 BS with the sanding frame which get's them damn near flat. It's not that I'm opposed to using hand planes as I have and use several nice ones. It's just a matter of time and/or money because if it's for me my ww time is valuable and if it's a commission I don't want to turn a $50/hr estimate into a $5.00 hr net. I think we tend to over romantisize the lure of the hand plane. When you get down to it, it's manual labor, the old timers didn't have a choice and they had apprentices that worked for squat to do it. Every notice most of the articles in the mags, the proponents of handplaning are ususally working on some relatively small piece and it's pine or cherry which are relatively soft and straight grained. For once I'd like to see an unplugged guy jointing the edges for a six board 8/4 x 9' top of something really hard like the figured 40 year old Koa my table is made of with a #8 :)John O'Connell - JKO Handcrafted Woodworking

Life is tough. It's tougher if you're stupid - John Wayne
Froed | Apr 21, 2004 07:13pm | #7
Do you have all your clamps on the same side of the glue-up? If you do, and you use a lot of clamp force, they'll give you a cup across it. I alternate my clamps top and bottom when I glue a panel. I'll wrap a little wax paper around the clamp bar where any squeeze out may happen, so I can snug the bar up tight to the boards. Then you can eyeball how straight your boards are (assuming your clamp bars are straight), and use a deadblow mallet to tweak any misalignment (I usually don't use biscuits). If your edges are square to the faces, you'll have no problem.

Of course that won't help your current situation...

In that case I'd use a jack or jointer plane, or belt sander to get it mostly flat. "Mostly" meaning close enough that someone will have to take a good hard look and maybe a straightedge to see it's not perfect - no sense being anal.

Froed
ian | Apr 23, 2004 03:50pm | #12
could it be that some of your edges are not exactly 90deg to the face? this could cause some joints to align in a V shape.

the other option is that your clamping pressure is not evenly distributed across the top and bottom of th glue up. Uneven top and bottom pressure will cause some cupping which will vary across the panel depending on the grain orientation of individual boards. With the clamping pressure released this could manifest as a step, V effect at some but not all joints.

Ian

scooter1 | Apr 21, 2004 02:16am | #4
It is usually less than a 32nd, and I just belt that baby down.

You can also take the table to a hardwoods supplier which might have a 48 inch wide belt sander and have them true the top. For $20, thats what I do.

Regards,

Boris

"Sir, I may be drunk, but you're crazy, and I'll be sober tomorrow" -- WC Fields, "Its a Gift" 1934

RANGERP75R | Apr 21, 2004 04:46pm | #6
yeildmap

BossCrunk said it! I second it. The only thing I might add to what he already said is I might use a hand scaper or scraper plane for the final touch.

Regards...

sarge..jt

Proud member of the : "I Rocked With ToolDoc Club" .... :>)
Tao | Apr 21, 2004 10:08pm | #8
I wrote a description of a different way to glue up here: http://forums.taunton.com/tp-knots/messages?msg=17407.11 Maybe it will give you a couple of ideas.

Production glue-ups are often done on clamp carriers with pneumatic panel flatteners, or else spring loaded cauls. Even these don't give dead flat glue-ups. We lost close to 1/8' in flattening 8/4 oak table tops we made regularly for a big chain of restaurants, and that's with abrasive planing on a heavy duty widebelt sander. That was probably a worst-case situation. If you are careful and have good wood, 1/16" or less would do.

Alternating clamps from one face to another is a good idea.

If you use cauls for flattening they should be made of 3" (net) deep staock at least, and it helps to keep the center flat if you plane about a 1/16 to 1/8" arc into the clamping face so it contacts the center first and distributes more uniform pressure.

I have a Stanley #40 scrub plane, but for large table tops I have an old Sargent jack plane (any brand will do) on which I set the frog back all the way and ground about a 1/16" arc into the blade like a scrub plane. It makes short work of flattening most tops if you plane diagonally, first in one direction, then crossing your previous cuts. Further flattening with a jointer plane and smoother does a surprisingly quick job.

When I first started woodworking full time around 1970, we did all our finish sanding with belt sanders and orbital sanders, so I have a lot of experience with them and know what they can do. Still, my first choice is the homemade scrub plane. I'll only use a belt sander with 24 grit if the planes simply won't do the job. The more experience I get (after 30 years full time I still need at least ten more years to get really good) the less I find use for the belt sander on this kind of work.

Michael R

Edited 4/21/2004 3:31 pm ET by Woodwiz
billballeza | Apr 22, 2004 05:11am | #9
I recently made my first table. Walnut writing table 24x54. The top was four, 4/4 walnut boards I milled down to 3/4 from rough stock.

I used six Bessey K clamps.. no cauls. After glue clean up with a scraper I planed with my LN #5. Then I used my belt sander.. 80 grit.. diagonally up and down in two directions.. then with the grain. I finished up with my random orbit 100 to 220.

I applied Maloof's oil/poly (6 coats) followed by wax/poly.

Not to brag.. but.. now I'm afraid I'll never be able to duplicate this effort.
MatthewSchenker | Apr 22, 2004 05:22pm | #10
Yieldmap,

I know what you're talking about here!

I have tried belt sanding and power planing.

Then I bought the Festool sanding system, which is totally dustless and very low vibration. I have the Festool ETS 150/5 6" sander, and I set it to its aggressive mode, using 24-grit paper to flatten the top. It does the job! After that, I go up the grits, all the way to 220. If someone wants a really silky feel, I'll go to 400.

I have 800 grit paper to use between coats of polyurethane.

Edited 4/22/2004 9:45 pm ET by Matthew Schenker
whoover | Apr 23, 2004 12:06am | #11
Look for a cabinent shop, millwork shop or lumber yard with a wide belt sander. In our area, they are readily availabe and very cost effective. I never worry about perfect allignment since I always run my glue-ups to the local lumber yard and get them sanded flat.

Bill