Tabletop advice pls

[John Helles]

Hi,first post here, need a little advice on a tabletop I'm trying to make. Approx 76" x 36" made from about 7 planks of 1 1/2" fir. Boards are all made as flat and square as I can manage, but obviously not perfect as when I line them up there are some gaps (about 1/16") between parts of the boards. The edges are square to the face, very little or no bow, so I think the gaps must be due to a small amount of crookedness. Due to thickness, I think it would take a lot of clamping pressure to closeup the gaps completely.

My questions:

i) how perfect do you usually have your boards before gluing up? what is an acceptable gap?

ii) as I've already taken my best shot with the jointer/tablesaw/planer, whats the best way of getting rid of the gaps before gluing? Edge sanding? (I am terrible with a hand plane).

iii) in general, what do you use to tell if a long board is really straight? I've nothing straight and long enough to use as a "true" reference. I can only tell these boards must be crooked due to the gaps that appear when they are alongside each other.

Thanks in advance for any replies!

[Sam Stephens]

In general no gaps is the goal. You can have a slight gap (hair's width) in the middle (not the ends), if you can close it by moderate hand (not clamp) pressure, but a 1/16" is way too much. Even if you close it w/ clamps, it will open with time.

Edge sanding won't do it so don't waste your time.
Jointer plane is great if you can use one, but this wouldn't be the time to get those skills.

If you have a jointer that is by far the best way to joint the edges. The edges only have to be straight relatively to the board it will be edge glued to, so that is the only reference I use. How big is your jointer bed b/c it can make a difference on long boards like yours? Set for a very, very light cut when you do this and pay close attention to your hand pressure. You're job is only to move the board laterally across the cutterhead and maintain a flat reference on the outfeed bed. Do not press down on the board across the cutterhead. Let the jointer do its job. I do the boards in sequence, compare them and continue light passes until there is no gap. Then move on to the next edges.

HTH,
Sam

[Matt Day]

I agree that 1/16 is too much. Did you buy the wood from a big box store, and have they been jointed and planed at all?

Regarding the edge jointing, you can use a flush trim but with a router and a straight edge if you don't have a jointer.

[Tom Hammond]

An old trick for miters can work here. Lay two of the boards together in the configuration you want, clamping them to the table but not to each other... then run a saw down the join. You end up with a kerf, but the board edges are then matching, even if not perfectly straight (Use of a straightedge is recommended). One or two passes through the jointer on each edge to clean them up and you're good. My question would be, though... if you're looking to perfect the gap, why are you using fir?

[Ken Krawford]

Try rearranging the boards in a different order. You may be able to decrease the gaps if the edges of each board have varying degrees of "straightness". Also try flipping them end-for-end.

[John Helles]

Thanks for the responses .....

I have a 6" jointer, 46" long. But the boards are about 80" long and I guess I'm having problems getting them 100% straight due to their length. I did setup infeed / outfeed rollers but its hard to get it all perfect.
I thought about using a router .... but I don't have anything 80" long and dead straight to use as a reference / cutting guide.
The wood started as rough cut and I did the normal joint / plane / cut sequence. Using fir because I was given some of it, and buying this much hardwood would cost a fortune.

[Mel Fulks]

How wide are the boards and are the gaps all at ends ,all in middle ,or some of both?

[John Helles]

The boards vary from 3 - 6 " wide; gaps are pretty much all in the middle.

[Sam Murdoch]

You write that you have set your jointer tables properly to each other but, if you haven't already done so - you should check your jointer knives too. Reset them to insure that they are all set equally in height to each other and to the outfeed table. Worth the effort.

[Jacob Reverb]

I did the normal joint / plane / cut sequence.

For me, on a tabletop, the "normal" sequence is rip, cut to rough length, joint, glueup, and hand-plane the top. There's not much point in jointing a board far longer than you plan to use because you'll waste a lot more wood as shavings. You also need a longer jointer table to joint longer boards.

[Steve Keathley]

An old trick for miters can work here. Lay two of the boards together in the configuration you want, clamping them to the table but not to each other... then run a saw down the join. You end up with a kerf, but the board edges are then matching, even if not perfectly straight (Use of a straightedge is recommended). One or two passes through the jointer on each edge to clean them up and you're good. My question would be, though... if you're looking to perfect the gap, why are you using fir?
That's a great tip. I don't yet have a Jointer and need to join some long stock. I was trying to figure out a way to use my TS, but this could be done with my track saw.

[Mel Fulks]

With gaps in the middle I suspect out feed table is a little high or knives are slightly dull ,or both. You are probably better off not adjusting the table. If you have good clamps try clamping up WITHOUT glue .If the clamps close the all the gaps ,go ahead and glue. If they don't close all the gaps ,try clamping half of the pieces ,if that works just glue that half .Use same procedure on other half of table. Then joint both halves and clamp without glue. If that pulls up ,go ahead and glue.Make sure you are using a sharp portion of the knives. If none of this works,let us know.

[Dan Keeling]

Check out the green section for a simple way to get straight edges.

http://ia801704.us.archive.org/BookReader/BookReaderImages.php?zip=/34/items/american-woodworker-105/american-woodworker-105_jp2.zip&file=american-woodworker-105_jp2/american-woodworker-105_0026.jp2&scale=4&rotate=0

[John Helles]

Thanks but what I do not have is an 7' straight edge, and I'm not sure I can cut anything that long that straight (ie not even 1/16 out over 7').

[Dan Keeling]

In the picture they used the factory edge of a piece of 1/8" hardboard. Steel studs also make for an inexpensive guide.

[Mel Fulks]

The question of whether a joint can be open in middle has been extensively covered.IMO best by Charles Hayward. I have glued thousand of panels with hollow in middle without failure. Letting ends slide around while gluing is a much bigger deal ,I have seen joints glued with open ends pop loose the next day. Good luck.

[John TenEyck]

It is absolute rubbish that you have to have a long jointer in order to successfully joint long boards. Yes, it's helpful, but it's certainly not a requirement. I often joint door stiles (that's nearly 7 ft) on my Inca jointer which is about 42" long. That's far longer than any hand plane, and they work. If you look down the edge your eye will tell you if the board is straight; when you hold two boards edge to edge you'll see whether or not the really are. It's just a matter of practice, whether you use a jointer or hand plane. If the board has a gap in the middle, press down harder on the front and back edge of the board as you pass it over the jointer. If it's rockered, take a couple of passes only in the middle to get rid of the rocker, then take a pass down the entire length. It's no different than you would go about it with a hand plane. Let your eye be your guide - and practice.

John

[John Helles]

Well I followed some of the advice above and took some very light cuts on the jointer and the gaps in the middle have dissapeard but I did create some small (about 1/64") gaps towards the last 6-12" of the ends of the board. I can close these with the clamps but am not sure if they'll stay closed long term.
Am I winning or loosing?

[John TenEyck]

You're almost there. Take a light pass on the piece that's rockered and check the fit. If both pieces are rockered take a light pass on both, then check. Try to make your passes in one continuous motion, concentrating on holding the board flat on the outfeed table and tight against the fence. In a perfect fit up you can stand the boards up on your bench, one on top of the other; a square will fit right up against them perfectly and there will be no light showing between any of the joints. That's your goal. An easier way to get there is to just focus on pairs. Get two boards to fit perfectly and glue them up, then joint and glue those up until your done.

John

[Aleks Hunter]

+1
If you don't have access to a jointer to get them truly flat, make them match each other!

[Jim Matthews]

This is one of the first applications of handplanes that really worked for me.

Search "match planing" and touch up what you have with the longest hand plane you can get sharp.
If you're doing this with a jointer, make certain that it's firmly set so it can't tip toward the outfeed end
when the board is fully extended.

If you're using rollers to "catch" the board past the outfeed table, that's where the board tips up or down relative to the cutter.

I'm not strong enough to handle a board this size with any facility.
I can certainly manipulate a handplane over this length.

Jointers are excellent because they can take off so much material in a short time.
Jointers are troublesome because they can take off so much material in a short time.

(Not my favorite tool)

[Brian Tymchak]

Thanks but what I do not have is an 7' straight edge, and I'm not sure I can cut anything that long that straight (ie not even 1/16 out over 7').

When I started my workbench build I bought one of these (http://www.homedepot.com/p/t/100188970?storeId=10051&langId=-1&catalogId=10053&productId=100188970&R=100188970#.UeK3K6W5Mo0), or something very similar, from one of the BORGs. While not a precision instrument, it is certainly good enough to set stands for jointer/planer/TS, etc. I found it accurate enough to use as a reference for "flat" as I assembled my bench tops. I use it for many other tasks around the shop/house. For me, I consider it $20 well-spent.

With this straight-edge, I set stands about 60" from the end of my jointer (56") in/out feed tables and I was able to get very good results with both face and edge jointing the laminates (~9' long) for bench tops.