Tips for jointing longer boards

[Barrett Rodgers]

Hello,

I have a small Delta benchtop jointer (6" wide, ~28" long), and am trying to mill some longer boards (40" table legs). I can pretty comfortably control the boards on the jointer surface for the full length of the board, but am worried that I'm not going to get a flat surface when face-jointing since the boards extend far past the infeed table to start and the outfeed table once passed through. Any recommendations or tips for how to address?

J

[Brian Holcombe]

Joint two boards and compare them to one another. You’ll know if your concerns are valid at that point.

[Prashun Patel]

Try it. When you / if you have issues, we can diagnose.

[Myles Moran]

You should be fine. 1.5x the bed length is a good rule of thumb. I've got a 6' jointer and have flattened some decently warped 8' boards on it just fine.

[Frank Pratt]

If it seems like the beds are too short then build bed extensions. I've done that & it works well. Just be sure to line them up well.

[glenn bradley]

There's a lot of discussion on this here although the search engine is pretty poor. Essentially the jointer, like the tablesaw, planer and other fixed cutter tools, expects a reliably consistent feed path. If your material is longer, wider or heavier than your machine can handle on its own, add outboard supports.

CoD-crnr-wide (1).jpgCoD-crnr-wide (2).jpg

[David Stone (CT)]

I had that exact jointer back in the day. Using the three options below, I managed to make some stuff with it, notwithstanding that the beds are far too short to be practical in many situations or even workable in some. None of these options are perfect but, hopefully, they can get you by, as they did me:

1. Build extension beds that can be clamped down on each end of the jointer--basically boxes with flat top surfaces that are coplanar with the infeed and outfield (set the infeed for a light cut). I don't remember how long I made these extension beds, but maybe 2' on the infeed side? Ideally they'd be totally flat and perfectly aligned, but in truth absolute perfection isn't necessary and a hair low is OK. The reason for making actual extension beds, as opposed to just roller stand-type supports that people sometimes use in conjunction with larger jointers, is that you need longer reference surfaces, especially on the infeed side, to make this jointer do what you want, not just some extra stock support.

2. Make and use a router sled for face jointing anything whose length and/or width exceeds the bench top jointer's capabilities.

3. Use the jointer as is and see if through some combo of technique (e.g. knocking down the highest spots with a hand plane before face jointing), luck and trial and error, you can get close enough.

[Dave Mount]

A 40" table leg on a 28" jointer is no problem assuming the jointer is set up properly in the first place. A table leg that short is going to be stiff enough and light enough that the cantilevered material is not an issue -- stiff enough to not sag, and light enough that you can keep it down on the table while cantilevered. That's the short answer to your question. Because I think jointers are fascinating machines, I'll add a bunch of comments that go well beyond your immediate project.

Jointers are capable of straightening stock much, much longer than their beds. While wrapping some laminated beans with pine boards, I decided to see if I could joint straight edges on 12' boards on my 8" x 72" jointer -- no problem to get boards to match perfectly. Even though only a portion of the board is on the bed at any one time, the geometry of how a jointer works will bring a longer cut to "essentially" straight. One difference is that when straightening something a lot longer than your bed, it's best to take more passes with a lighter cut. Explaining why would be hard without drawing pictures. You are basically taking a concave edge and replacing it with successively less concave edges with each pass until the edge is functionally straight. In truth it won't ever be "perfectly" straight, but for building things from wood, that's an unimportant nuance.

Face jointing long stock presents some additional challenges beyond edge jointing. When you're edge jointing, you have a board in an orientation where the unsupported portions of the board won't flex much. When face jointing, a substantially cantilevered board will tend to bend under it's own weight, more so the thinner the stock. Flex in an unsupported span decreases with the square of the "depth", which when face jointing is the thickness of the stock. You can take some of that out by pressing down on the face over the tables, but you don't really want to be applying a lot of force when jointing; any time you are applying a lot of pressure when using a machine, there's more chance of something going catastrophically wrong. In that case, better to put some work support out there.

Another consideration is the tolerances of the work. For most applications where you're face jointing a long board (much longer than your table legs), it's usually most important to have the face flat side to side and parallel along its length (i.e., not twisted), but less important that there is zero bow, because if the piece is long and thin enough to flex when unsupported by the jointer, then it's likely that whatever assembly it's going into will help hold it flat, because by definition it can't support itself. You can glue up a fine tabletop out of boards that have some bow in them, as long as the boards are only bowed and not twisted. And taking the twist out of a long board on a jointer with unsupported ends much simpler than getting zero bow (though you can do both if you support the overhang).

If you can't joint a 40" leg straight on your 28" jointer, then you're probably not getting 28" pieces straight either, its just that you're not noticing the defect in shorter pieces. A well aligned jointer is an amazing tool.

Best,

Dave

[Patrick Walsh]

Other than extending your infeed and outfeed table. And it’s gotta be adjusted spot on flat.

These can work pretty darn good. I use simular at work and the crank handle allows you to take a straight edge and get them just so. You can compensate for a spring vrs convex with them and or a giant piece of lumber that want to sag on its way over the cutter o the trailing edge or after the cutter on the leading edge.

It sucks but it can work once you wrap your head around it and succumb to the suck.


https://www.amazon.com/Woodstock-D41.../dp/B005W176ZO

[Andrew Hughes]

It’s just a table leg how straight does it really have to be.
A little curve in the right direction can look pretty nice.

Good Luck

[Wes Grass]

I did some 7' pieces today, that had been ripped (bandsaw) from 10" wide planks. On one of them, the kerf had opened up to about 1/4" after 5' had been cut.

I'd normally joint concave side down to ride the high spots at the ends. But I'm mostly doing short pieces. On these, I went convex side down, but shimmed the leading end with tape so it was about level on the tape and high spot in the middle. First pass gave me enough straight edge to ride the tables normally.

I thought about running multiple passes concave down and see where it got me, but some of them had less extra width than I was comfortable experimenting with.

Edge to edge I've got less than a 32nd between a pair, so more than good enough.