Glue lines

[David Klug]

The project I'm building requires glueing 10' boards togesther. The challenge! How do I get the edges mating perfectly so that I don't have a hair line crack some where along the edge?

DK

[Brian Dormer]

Joint the edges. Put in biscuits (cut the biscuit slots a bit towards the hidden side of the centerline). Glue it up with a good quality woodglue (Titebond II) and clamp at least overnight.

Instead of biscuits, you COULD use dowels (hard to keep everything on line) or pocket screws. But I still think biscuits would be best in this application.

When the glue is dry, use a paint scraper to scrape off the squeeze out. Sand with a random orbit sander, starting with the coarse grits (80 or 120) and progressing up to the finer grits (400 to 600).

Finsh however you want.

That being said - a 10' board is going to move around a good bit with temperature and humidity. So even if you do everything perfect - it's still possible that the joints may open up given enough time. But this will give you the best shot at a "perfect" joint.

bd

[Vaughn McMillan]

Not sure I understand the question, David. By "hairline crack" do you mean a visible line, or an actual void between the two wood surfaces?

Unless you're very lucky, you won't be able to exactly match the grain of the two pieces of wood along the joint. Because of this, you'll have a visible line at the joint, but if the wood is properly prepared (smooth and square), glued, and clamped, there should be no actual crack between the separate pieces.

Here's an example of a glue joint where you can see the visible lines at each joint, but there are no hairline cracks:

http://workingwoods.com/workingwoods/Cutting%20Boards/Circus%20Stripes5%20DetailT%20500.jpg

HTH -

- Vaughn

[Jesse Cloud]

Its very hard to get a ten foot board dead straight, that stretches the capability of most jointers. Is there any way you could break the ten feet into smaller, overlapping lengths, sort of like overlapping bricks?
Maybe if you explained the project to us, we could help.

[David Klug]

Its very hard to get a ten foot board dead straight, that stretches the capability of most jointers. Is there any way you could break the ten feet into smaller, overlapping lengths, sort of like overlapping bricks?
Maybe if you explained the project to us, we could help.

The glue up will be the top of a cupboard that will angle about 25 degrees so you can display things on it. The total size will be 10' long by 16" wide and about 50" tall. When I butt the peices together I have hair line cracks that show up along the edges. Would sanding and using glue for a filler work? When I've tried this before it looked like a patch job and I wasn't satisfied with it. I'm open to any ideas.

DK

[Don Baer]

When I joined the top for the Maloof table I recently made I wanted to avoid any voids so I used a hand plane with a shooting (chuting) board to make sure the edges were perfectly flat. I still had a slight glue line but no void or cracks.

[Shelley Bolster]

Wow - 10 feet long is going to be a challenge David. You didn't mention how many of these 10' boards you are planning to glue up together. One way that I have to insure a good panel glue up - I never glue up more than 3 boards at a time.....often, only two reducing the number of joints I have to bring together. Four instance, if you have 4 board to glue up, I will glue 2 and 2....let set for a minimum of 3 hours and then glue those two "halves" together. I also like to cheat and keeping sections under 12 inches, run them through my 12 1/2" planer, (makes a nice smooth section) then, I glue up the planed panels until I get the width I am after. Doing that often only leaves one joint to worry about - really reducing sanding time. Course....if I had a wide belt sander :rolleyes: .

I seldom use a jointer - I find I get a better edge right off the tablesaw and I prefer a regular kerf blade to that of a thin kerf. (no flexing of the blade during the rip)

Like Brian, I also use biscuits to aid with the alignment however they are not necessary......cauls will work pretty good keeping everything flat.

I don't bother worrying anymore about alternating growth rings - I instead look for better grain match - often a time consuming job but time well spent IMO.

Below is a door panel - one of many. :cool: 5 boards right off the table saw.


http://img.photobucket.com/albums/v99/shelleybolster/103_3267.jpg

[David Klug]

That looks terrific Shelly. I'm using quater sawn oak wasn't able to get a terrific grain match.

DK

[Barry O'Mahony]

Instead of biscuits, you COULD use dowels (hard to keep everything on line) or pocket screws. But I still think biscuits would be best in this application. Really? I've found that there is enough "slop" between the the thickness of the biscuit slot, and the thickness of the biscuit, that they don't halp much with aligning panels. Routing slots and using tight-fitting splines work better.

Actually, I've had good luck using cross-wise cauls (jointed 2x4's with packing tape on the edges to prevent glue sticking) to keep the panels aligned during glue-up. Assuming you have the clamps available, it's cheap and easy.

[Tom Jones III]

I do the exact same as Shelley and have had fine results. The only difference is that for long boards I will always run it through the jointer.

[tod evans]

david, for rips over 8` i turn to a shopmade straight edge that i lay on top of the board. i make mine out of plywood, 4-5" wide and affix a small 1/2x1" ledge to one side, i`ll hook this ledge to the edge of the board and pressing the straight edge against the saw fence make a rip. then remove the straight edge and parallel the cut. i use no mechanical alignment devices when gluing, just start clamping at one end and flush the joint as you go, if it`s stuborn a pair of deap reach vice grips will usually force it into submission...02 tod

[Mark Singer]

david, for rips over 8` i turn to a shopmade straight edge that i lay on top of the board. i make mine out of plywood, 4-5" wide and affix a small 1/2x1" ledge to one side, i`ll hook this ledge to the edge of the board and pressing the straight edge against the saw fence make a rip. then remove the straight edge and parallel the cut. i use no mechanical alignment devices when gluing, just start clamping at one end and flush the joint as you go, if it`s stuborn a pair of deap reach vice grips will usually force it into submission...02 tod

Tod,
It sounds like my aluminum storefront extrusion I use for straight lining

[tod evans]

Tod,
It sounds like my aluminum storefront extrusion I use for straight lining

same thing! works just fine :) i like low-tech! .02 tod