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How to join slabs

Started by Ljohnsaw, October 03, 2015, 02:04:03 AM

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Ljohnsaw

I was asked to make a live edge slab for my niece's dinning table.  My cedar (incense cedar) was not wide enough so I book matched two slabs.  I will joint the straight edge and want to glue it up.  The slab is currently 2-¾" thick and will plane it down (with a router shuttle setup) to somewhere between 1-¾ to 2-¼".  I typically do my woodworking joints with Titebond yellow glue.  Seems like that should be enough glue surface to support a 40" wide slab.  Not too sure of the final length so I'm hesitant to use biscuits or splines.  What methods would you suggest for this joint?  Glue?  I also have a few knots to fill - any particular epoxy I should look for?

Thanks!

 

 
John Sawicky

Just North-East of Sacramento...

SkyTrak 9038, Ford 545D FEL, Davis Little Monster backhoe, Case 16+4 Trencher, Home Built 42" capacity/36" cut Bandmill up to 54' long - using it all to build a timber frame cabin.

Ianab

When I do that sort of build I use splines. Just route some matching grooves into the surfaces to be joined, then plane up a board to the same thickness as the router bit / slots. Cross cut them to slighty shorter than the depth of the slots.

If you get a good glue joint, that should technically be strong enough. But that can be tricky with large boards like that, so I like some mechanical support as well. It also helps with alignment when you clamp it up.

If you have to trim the ends yet, then maybe leave the end 6" or so un-splined. That way you have some trim area without exposing a spline.
Weekend warrior, Peterson JP test pilot, Dolmar 7900 and Stihl MS310 saws and  the usual collection of power tools :)

WDH

The glue will be fine if you can line up the slabs without splines or biscuits. 
Woodmizer LT40HDD35, John Deere 2155, Kubota M5-111, Kubota L2501, Nyle L53 Dehumidification Kiln, and a passion for all things with leafs, twigs, and bark.  hamsleyhardwood.com

warren46

When I need to glue up a wide surface like a table top I first plane the boards to very near final thickness.  I then joint the mating surfaces (2 at a time if there are more than 2 boards) together.  When edge jointing the two boards I put the edge to be glued of both boards down on the jointer.  That way when the 2 boards are laid down or opened like a book, the edges will be tight when the boards are flat even i the jointer is off of 90 degrees just a bit.

I then glue up the surface using cauls and plenty of clamps.  The bottom cauls have parallel edges and are set upright on my workbench which is 3" thick and known to be flat.  The upper caul is slightly convex.  When the boards to be glued are clamped between the cauls/workbench, there is even pressure from the edges to the center of the glue up keeping the boards aligned and flat.  Just a little sanding to eliminate any glue squeeze out and the joints almost disappear.
Warren E. Johnson
Timber Harvester 36HTE25, John Deere 300b backhoe/loader.

scsmith42

Titebond II or III would be my first choice.  It does not have a long open time, so you need to have everything prepared for a fast alignment and clamping when you apply the glue.

The best epoxy system that I am aware of is West Systems Epoxy.

I prefer the Titebond to the epoxy for glue-up's though.  The Titebond seems to penetrate deeper into the wood, providing a stronger overall joint.
Peterson 10" WPF with 65' of track
Smith - Gallagher dedicated slabber
Tom's 3638D Baker band mill
and a mix of log handling heavy equipment.

mesquite buckeye

Big pieces like that like to move around after the milling step. May not be much, but it usually happens. If you include dowels, biscuits or splines your final glueup will go more smoothly and you shouldn't see any little offset "surprises".
Manage 80 acre tree farm in central Missouri and Mesquite timber and about a gozillion saguaros in Arizona.

Magicman

I seldom have enough hands so I personally prefer to use biscuits/dowels on all edge gluing. 
Knothole Sawmill, LLC     '98 Wood-Mizer LT40SuperHydraulic   WM Million BF Club Member   WM Pro Sawyer Network

It's Weird being the Same Age as Old People

Never allow your "need" to make money to exceed your "desire" to provide quality service.....The Magicman

Just Me

Quote from: ljohnsaw on October 03, 2015, 02:04:03 AM
Not too sure of the final length so I'm hesitant to use biscuits or splines.  What methods would you suggest for this joint?  Glue?  I also have a few knots to fill - any particular epoxy I should look for?

Thanks!

 

 

What I do in that case is spline the middle and short splines on the end. You have a rough idea how long the table will be so I will spline up to about three inches of those marks, skip to the end and put a short spline perpendicular in the very end to help alignment and holding it flat. usually just a 3/4" by 3/4" piece of a hard wood like oak about 6" long. This short spline will be totally cut off when done and so there is no spline showing at all on the end grain when done.

I too vote for West System.

Larry

Ljohnsaw

Thanks, guys.  The reason for not knowing the overall length:  My niece is strong-willed and wants to put the table cross-ways in the dinning area  ???  That gives her about 64", she figures, and it will be 41+" wide.  This slab is a reasonable amount of work and I think once she sees it, she may change her mind and want to go lengthwise.  The entire slab is 8' long but has the funny taper that is about 20" with the most figure.  I could spline the middle section (2 or 3 feet) and big-spline at each end just to help with glue-up, then she can pick where to cut out her table top.

The wood is bone dry so I don't expect much movement (I could be wrong, know to happen on rare occasions  ;) ), so I plan to make a nice "milling" sled for my router and surface plane the entire slab at one time.
John Sawicky

Just North-East of Sacramento...

SkyTrak 9038, Ford 545D FEL, Davis Little Monster backhoe, Case 16+4 Trencher, Home Built 42" capacity/36" cut Bandmill up to 54' long - using it all to build a timber frame cabin.

Ljohnsaw

Well, it was a long time coming but it is finally done. The slabs were cut October 2015.  I glued up the slabs (January 2016) with Titebond III and use a 3" router bit with a sled to make it flat (both sides):

 

I delivered the table in April or May - don't remember.  My niece took it from there.  She sanded it some more because there was lots of movement around the knots at the small end.  Then she experimented with epoxy filling the cracks.  She finished it with a satin poly, ordered up the legs she liked and put it all together.  I think it came out great and her friends and co-workers are envious that she got it for "free"!

 

 

 

 

I'm so happy she kept the small end that has all the movement.
John Sawicky

Just North-East of Sacramento...

SkyTrak 9038, Ford 545D FEL, Davis Little Monster backhoe, Case 16+4 Trencher, Home Built 42" capacity/36" cut Bandmill up to 54' long - using it all to build a timber frame cabin.

ESFted

That really turned out nice.  Good job on the glue up.
S.U.N.Y. College of Environmental Science and Forestry '65
Stihl MS661CRM, Stihl MS460,  Stihl MSE 220, Solo 64S, Granberg Alaskan MK-IV CSM
Dreams of a Wm LT70 w/all the accessories

Magicman

Congrats to you and your niece.  You both did a superb job.
Knothole Sawmill, LLC     '98 Wood-Mizer LT40SuperHydraulic   WM Million BF Club Member   WM Pro Sawyer Network

It's Weird being the Same Age as Old People

Never allow your "need" to make money to exceed your "desire" to provide quality service.....The Magicman

OffGrid973

That is a great piece, good glue up on that joint !
Your Fellow Woodworker,
- Off Grid

WDH

Woodmizer LT40HDD35, John Deere 2155, Kubota M5-111, Kubota L2501, Nyle L53 Dehumidification Kiln, and a passion for all things with leafs, twigs, and bark.  hamsleyhardwood.com

Czech_Made


thecfarm

That small end adds alot to the table.
Model 6020-20hp Manual Thomas bandsaw,TC40A 4wd 40 hp New Holland tractor, 450 Norse Winch, Heatmor 400 OWB,YCC 1978-79

lowpolyjoe


Peter Drouin

A&P saw Mill LLC.
45' of Wood Mizer, cutting since 1987.
License NH softwood grader.

cbla


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