Tips for jointing long boards

[Matthew Curtis]

I am having a difficult time trying to edge joint some 8' boards. I'm not able to get as straight of an edge as the shorter pieces that I normally joint. I tend to get a cup in the middle. I am sure this is because of my technique. My table length is 59" and I have a 40" long fence that is 6" high on my jointer.

Is my difficulty the nature of the longer boards?
What can I do to improve my results?

[John TenEyck]

Longer boards are harder, to be sure. But if your jointer tables are coplaner it's just a matter of technique and practice. A cup in the middle suggests your tables might be sagging on the ends, or you are not holding the board high enough to start and finish which is easy to do when the board is long and heavy. FWIW, your jointer beds are plenty long enough to get a straight edge on an 8' board. I manage on an Inca J/P which had tables less than 40" long combined.


John

[Paul F Franklin]

Timely. I've just been jointing 10' and 12' boards on my relatively short jointer. I mentioned in another thread that I bought a couple of Bora PM-2700 expandable roller stands and they have made all the difference since the stock is fully supported both on infeed and outfeed and I can concentrate on technique and not keeping the board on the tables. I spent a fair amount of time to get the supports exactly co-planar with the tables, especially the outfeed side. If your board is more than twice as long as your infeed and outfeed tables, you really need extra support.

Since you are asking about edge jointing, a few things I have found helpful: If your boards have a crook, and most long boards will, concentrate on the ends first (arrange the board so the crooked ends of the board are down) and don't take full length passes. Start feeding, transferring pressure to the outfeed table as soon as you can, but don't bear down with a lot of pressure, just enough to keep the board on the tables. As soon as the knives stop cutting, stop and return the board to the beginning. After a few passes (depending on depth of cut), move the board toward the outfeed without downward pressure until the knives start cutting again. Take a couple of passes on this end of the board. Now you are ready to take full length passes, but again, don't put much downward pressure on the board, concentrate on keeping pressure against the fence. On a long board, even a fairly wide board, it takes very little pressure to flex the board downward against the crook and that is counterproductive. Until you get the hang of it, you may find it helpful to snap a chalk line on the outer face of the board that shows what a straight edge will be; then you can more easily visualize where you need to remove stock to get to a straight edge.

The same concept works if you just have a wavy edge and not much crook; just don't force the board down against the tables; allow the jointer to find the high spots and remove them. Chalk line trick works for these boards too.

[Patrick Kane]

If you put two jointed edges together, what is the gap between the two boards? 1/16", 1/8", more? 1/16" in the middle over 8' wouldnt bother me, and i would clamp it closed. Some call this a "spring joint". I call it a poorly jointed edge, but you can get away with it. 1/8"+ is where you should take action and correct the edge. Like John said, i doubt its your technique, but rather your tables are out. Have you ever checked them? Try focusing all your pressure ONLY on the outfeed side when you joint the edge next. Is it better or the same? Finally, if its close, you can take a hand plane to the far edges of the boards and get it closer to an acceptable gap in the middle. If youre touching on the ends with a 1/8" gap in the middle, then you only have to remove 1/32" from the far ends of the edges. thats a swipe or two of your plane for each board.

After the project when you have time, i would take a hard appraisal of your jointer. Its good to get very anal with dialing it in properly. I just put together a 93" by 38" walnut island, and my jointed edges were laser straight next to one another. My jointer's tables are a bit longer than yours, but you should be able to get workable results from 59" long tables.

[Tom M King]

Sight down the board, and develop an attack strategy. Table length makes for easier handling, but doesn't limit the length of boards that can be jointed. I see so many people having trouble who think they have to run the whole length of the board every pass. If I sight one, and see a hook on one end, the first pass(or several) may only run 6" of a 16' board over the cutterhead.

[Robert Engel]

I can be difficult trying to feed a long board while maintaining down pressure on the outfeed table.

I've found wearing rubber coated gloves helps me grip the wood better.

[Prashun Patel]

I second Patrick's post: While the cup is intellectually bothersome, if it's small enough, it may pull closed acceptably. I would joint your two edges as best you can, then put a piece of notebook paper along the joint. Clamp it 'normally'. If it holds tight everywhere under reasonable pressure, the edge is flat enough.

[Rod Sheridan]

My jointer is setup to produce a concave surface of a couple of thousandths of an inch over 3 feet.

If you joint 2 boards and place them edge to edge, how big is the gap?

Regards, Rod.

[Mel Fulks]

So far I have been able to refrain from debating. Jointer Perfectionists Anonymous is helping me. And unlike some other
help groups ...they serve drinks.

[andy bessette]

Use a track saw to straighten the edge.

[Matthew Curtis]

Longer boards are harder, to be sure. But if your jointer tables are coplaner it's just a matter of technique and practice. A cup in the middle suggests your tables might be sagging on the ends, or you are not holding the board high enough to start and finish which is easy to do when the board is long and heavy. FWIW, your jointer beds are plenty long enough to get a straight edge on an 8' board. I manage on an Inca J/P which had tables less than 40" long combined.


John

John, What do you mean by " holding the board high enough"

[Doug Dawson]

I am having a difficult time trying to edge joint some 8' boards. I'm not able to get as straight of an edge as the shorter pieces that I normally joint. I tend to get a cup in the middle. I am sure this is because of my technique. My table length is 59" and I have a 40" long fence that is 6" high on my jointer.

Is my difficulty the nature of the longer boards?
What can I do to improve my results?

If you put the boards edge-on and they don't match to your liking, you can always tweak the fit with a hand plane, a Stanley #5 would be sufficient (everybody should own one.)

[John TenEyck]

John, What do you mean by " holding the board high enough"

Probably a poor choice of words. What I meant was that the board has to be parallel with the tables. To get rid of a crook that's high in the middle you have to hold the board so that the middle is parallel with the tables. To better see what I'm trying to describe, snap a chalk line on your board to show what you need to remove, with the chalk line tangent to the arc in the middle of the board. You'll see that you have to remove a triangle of wood at each end. To do that you have to hold the board parallel with the joint tables with each pass. You will only remove a tiny bit of wood on one end with the first pass, then progressively more with each pass. I often work both ends first to remove most of the crook, then one or two passes over the entire length to get a straight, smooth edge.

John

[Andrew Seemann]

I've got a crummy 6 inch jointer. It is good for boards about 4 feet long, 5 if they are already pretty straight. Below is what I have found.



In general don't edge joint boards any longer than you need to. It may sound logical to thickness plane and edge joint all your lumber ahead of time, but it is better to thickness plane then rough cut for length. The shorter the piece the more accurate the edge jointing will be.
If the board has any significant cup, high spots, unevenness, etc., cut them out before you run it across the jointer. The longer the board, the more it will want to follow curves and dips. At some point you can't fight it anymore. I usually take a straight edge (chalk line will work also), mark a line about a quarter an inch from the edge, cut the line on the band saw, and then run it across the jointer.
At some point the boards will be too long for the jointer (for me that is about 4 feet). For those, I do the procedure above and then hit the edge with a jointer plane and then run it through the table saw with the hand planed side against the rip fence, and then use the table sawn edge as the jointed edge.
The alternative of course is to just screw an already straight board to the board to be edge jointed and run it through he table saw.


For most of what I do, 4 foot boards are enough, which is how I have survived with a 46" jointer. Someday though it will turn into a decent 8" jointer. Someday.

[Patrick Walsh]

For a long board convex side up so a banana with either tip on the cast table and belly up to the sky.

First throw the pressure on the outfeed table only right out the window with a long board like this and short machine.
Second gently from the trailing edge of the board guide the leading edge of the Board over the cutter. Don’t force the board down to the out feed table in the slightest until you can hear then see that your past the concavity and wood is making contact on both jointer tables both in front of and behind the cutter. At this point yes it’s import to shift your pressure to the other side of the cutter head. But nothing crazy just make sure you don’t let the board sag off the end of the unsuported outfeed table.

Take very small bites as to no vibrate the leading edge off the cutter as you will be largely pushing from the back or trailing edge of the board for most of the cut. Also take small cuts till your board gets closer to flat.

Hope that helps. Extension tables help. But it can be done without you just gotta read the wood.

One other thing. Sometimes wood just wants to continually release tension the same exact way. At times I just throw the board in the trash and start with a new one. If it’s expensive lumber I consider my other options. But if it’s a critical piece that Must remain flat and straight in the trash the problem board goes.

[Dan Jansen]

My friend and I recently had to join two 8 foot, 24” wide maple countertops into a 4’ wide island. The countertops were hit with a round over bit so we needed to rip a 1/4” of one side on both. We looked at the jointer. We ruled it out very quickly since they were so heavy. We considered my #7 jointer but hand planing 2” thick maple down a 1/4” and maintains a square edge is beyond my skill set. So, we tried ripping it using my PM 66 table saw but the fence wasn’t long enough to work right. We ended up clamping one countertop as a fence while ripping the other. It worked dang near perfect. We had a tiny gap that pulled tight with the clamps. So, I’d try a glue line rip blade and a beefy homemade fence, you know, something like a 24” wide maple countertop with a factory edge you have lying around.

[Mel Fulks]

Patrick, Have seen it in print a number of times, but I think avoiding liability issues is the
origin. Facing with convex side down often makes a board straighten some instantly; when it does not work it never makes the board bow more. The other way tends to make the problem worse, but I'm glad it has worked for you.

[Patrick Walsh]

So your point or the thinking must be “take the belly out” the stress is thus released and the board stops moving in that direction?

It normally works my way, but as said sometimes I throw boards in the trash. I’m often trying to get a .75x1.5x120” piece perfectly flat to say miter wrap.

I say this with no attitude being you may have taught me something and I mean that. But I tend to not pay attention to what read in books and rely more on what I learn from in practice.

But with that said you mentioning the technique reminds me I have also read that here or there but somehow with all the hours I have behind a jointer I never once thought to approach it that way. Sure I’ll joint a board concave side down dropping the middle into the cutter but it was never with the intent that the board would stop moving but rather for another reason “who knows what” it seemed the best approach. Could be a hunch of bark a giant piece of tear out, a knot bake bake blah, could be anything.


Patrick, Have seen it in print a number of times, but I think avoiding liability issues is the
origin. Facing with convex side down often makes a board straighten some instantly; when it does not work it never makes the board bow more. The other way tends to make the problem worse, but I'm glad it has worked for you.

[Andrew Hughes]

I’m with Mel , I try to create a flat in the middle of my board edges or faces. I do think the wood will relax in my favor.
I have no scientific proof or videos. Sorry

[Mel Fulks]

I worked with guys who remembered the depression. They did not often give tips to those they thought might get their
job. But when they were being leaned on to "get it done" they would do what they could to speed us up ! And it's good
bar bet material !

[Mike Wilkins]

You have plenty of jointer bed length to surface your lumber, so maybe your technique needs adjusting.
You can also get a straight edge from the table saw by mounting a board to a plywood carrier which runs along the fence.

[Osvaldo Cristo]

I am having a difficult time trying to edge joint some 8' boards. I'm not able to get as straight of an edge as the shorter pieces that I normally joint. I tend to get a cup in the middle. I am sure this is because of my technique. My table length is 59" and I have a 40" long fence that is 6" high on my jointer.

Is my difficulty the nature of the longer boards?
What can I do to improve my results?

Wood is a flexible media and bigger it is, more prone it will be to have a significant flex so pay attention to downward force you apply when planning those long pieces... for some extreme cases even the own weight of the piece can compromise you end results.

[Alex Zeller]

Sight down the board, and develop an attack strategy. Table length makes for easier handling, but doesn't limit the length of boards that can be jointed. I see so many people having trouble who think they have to run the whole length of the board every pass. If I sight one, and see a hook on one end, the first pass(or several) may only run 6" of a 16' board over the cutterhead.

This has been my go to technique as well. Take a little off one end, spin the board around and take a little off the other end. Then look down the board to see how much further you need to go. If I have to do a second pass like this I'll usually go twice as far as the first pass.

[Mike Cutler]

I am having a difficult time trying to edge joint some 8' boards. I'm not able to get as straight of an edge as the shorter pieces that I normally joint. I tend to get a cup in the middle. I am sure this is because of my technique. My table length is 59" and I have a 40" long fence that is 6" high on my jointer.

Is my difficulty the nature of the longer boards?
What can I do to improve my results?

Matthew
The key is stabilizing the material through the jointer. You need to cobble together some additional infeed and out feed supports to take the weight of the material out of your hands.
As for your tables, cut a 2x4 the length of your tables. Run it through face down until it's flat. Edge joint the 2x4 now, and then run it through one more time, face down, stopping 1/2 way through. Remove the board relieve a 2" wide space across it, maybe a 1/4" deep, right over where the cutter head was at when the board stopped.
Put the 2x4 back on the jointer, align the relieved section with the cuttehead. Move your fence into the table approximately the width of the material you wish to edge.
joint.
Align the 2x4, which should have one edge jointed with the fence, face down, with the cutterhead centered in the 2" wide relieved area. Now clamp it down on both tables.
Move the fence out of the way and then set the material to be jointed on edge, against the 2x4.
Move the fence back in and ever so lightly until it just "clamps" the material between the 2x4 and fence. You're not really "clamping" the material, you're just making sure that it has to remain in a vertical plane. Now your material will stay upright and aligned to your fence.
With the auxuiliary infeed and outfeed supports, and the 2x4 clamped to the table, you no longer have to control the weight of the board, and are free to concentrate on technique.

I have edge jointed 6/4 jatoba, 11' long, and 16" wide, using this method on a 6" Jet jointer, end to end, less that 48". If you can edge joint a 4' board properly, you can edge joint those 8' boards properly. You just have to get some of the weight out of your hands.