Jointing plywood?

[Dave Norris]

This is a spin-off of Adam Cavaliere's jointer knife post...

How DO you joint plywood?

I was always taught to avoid jointing as the glue/end grain was hard on knives. But I was taught that before ply was really so prevalent in building. I do it on the very first inch of the jointer blades, so when I need to joint good boards, I just move the fence over to cover the nicked "plywood part" of my knives.

Same question for planing two boards that have been glued up. How do you do that? I just avoid it altogether... but it sure would be handy sometimes.

[Joe Scharle]

I use a spiral bit and straight edge.

[Howard Acheson]

Personally, I never joint plywood. I've never found a need to do it. What do you do that need to joint plywood?

Almost all plywood uses a urea formaldehyde adhesive. UF adhesives are very hard and you will risk chewing up you jointer blades.

For glued up panels, there is no reason not to run them through your jointer of planer. PVA adhesives are actually rather soft and will not damage tool blades. But, I do remove squeeze out glue with a scraper before jointing or planing. That's mostly to prevent the glue from building up on the tooling knives.

Keep in mind, the edges on tooling well eventually need to be sharpened or replaced. You need to trade off using the power tooling verses hand tooling. To me, my time is more important than the cost of replacing or resharpening blades.

[Paul Gatti]

Like Howard, I've never run plywood through the jointer. A good blade in a table saw is all you need to get a good edge. As far as putting two boards that have been glued up through the planer... I'm assuming that you are talking about solid wood boards and not plywood. If they are joined correctly, I usually only need to hit the panel with the belt sander or a scraper. You can run it through the planer, but just make sure one side is perfectly flat or you'll end up with a panel that's not same thickness all the way across.

[glenn bradley]

Like the others, I'll assume you are NOT talking about face jointing. A good blade will do the job, no jointing needed. If you are on a large unwielding piece, a router bit as Joe describes works for me.

[Rich Engelhardt]

Hello,

How DO you joint plywood?
I use a shop made jig for the table saw.

www(dot)woodworkingtips(dot)com/etips/2005/01/28/wb/

I used some scraps of old particle board shelves to make it.
Took all of about 20 min.
Once made, it sets up in seconds.

[Walt Jaap]

Concur with most all the comments, but on occasion there comes the need. Say you are fabricating a jig, you glue five pieces of 3/4 plywood, trying to ensure the endgrains are flush, but that is challenging. The glue up results in a mass that is approximately 3.75 x 6 x 24. The longer endgrains are not flush, they exceed the height of a 10 inch table saw blade. So, how to square up so the jig performs to expectation. Joiner, hand plane, band saw. Tomorrow I will figure it out.

[Kyle Iwamoto]

Something big, I'd grab my beater chisel and a diamond home. Use a mallet to chip slowly. Sharpen often. Finish with a plane/scraper. I guess you could use a "good" chisel too.....

[John Schweikert]

Bingo. I've done this quite a few times. I just recently sandwiched a bunch of layers of plywood to mount to my Keller jig as the backing board. After the plywood pieces glue cured, I jointed the structure to get it squared. The ends of plywood always chip out on the jointer, so I make the pieces longer than needed, glue, joint, then cut to length on the bandsaw. It's all for function, for jigs and such, and nothing more.


Concur with most all the comments, but on occasion there comes the need. Say you are fabricating a jig, you glue five pieces of 3/4 plywood, trying to ensure the endgrains are flush, but that is challenging. The glue up results in a mass that is approximately 3.75 x 6 x 24. The longer endgrains are not flush, they exceed the height of a 10 inch table saw blade. So, how to square up so the jig performs to expectation. Joiner, hand plane, band saw. Tomorrow I will figure it out.

[Frank Drew]

I've done it on the jointer if I haven't gotten a good enough edge on the table saw, but only on the long grain edge of the ply's face veneer. I'm sure the glue dulls the jointer knives over time but doing an edge or two every now and again (I mostly worked in solid) never presented a problem. And, anyway, dull knives are why they have sharpening services.

[Mel Fulks]

Any one who owns a jointer probably doesn't joint plywood much and any employee who does that using any portion of cutter head other than the last inch on a wide machine would deserve to be fired. Unless it has carbide knives.

[Stephen Cherry]

Any one who owns a jointer probably doesn't joint plywood much and any employee who does that using any portion of cutter head other than the last inch on a wide machine would deserve to be fired. Unless it has carbide knives.

That about sums it up. If I want a strait edge on plywood, I use the saw. As suggested, a spiral bit and strait edge would do it also.

[Jeff Duncan]

Any one who owns a jointer probably doesn't joint plywood much and any employee who does that using any portion of cutter head other than the last inch on a wide machine would deserve to be fired. Unless it has carbide knives.

Damn....I'm going to have to fire myself:D


I joint everything wood based and even some plastics on my jointer. It's a machine that exists to make my life easier and as such I use it to do so. I joint melamine, plywood, mdf, you name it. It's all about perspective....I build projects that usually cost several thousand to tens of thousands of dollars. The cost of sharpening a set of blades is less than a hundred bucks. I'm not going to spend a lot of time making an elaborate jig when I can just zip something through the jointer. FWIW the blades can take a good amount of edge jointing in mdf, and melamine....ply is the worst. If you run hundreds and hundreds of feet you will wear a spot out, but if your running a lot just keep moving the fence every so often. I usually do try to keep it to the back several inches though, just in case!

As far as glue-ups I don't take any special care there either. I do scrape the heavy stuff off of glue-ups first, but I don't find yellow glue does a lot of damage.

good luck,
JeffD

[Dave Zellers]

I do it but not without cringing. BB ply is the worst. I did a bunch of BB for some drawers once and ended up with about 6 perfectly spaced nicks in the knives.

But since I sharpen my own knives, I wasn't bothered too much but I do think twice about it now and only do it if it's really necessary. In fact, just today, I wanted to do it but the job didn't really need it so I didn't.

[Mel Fulks]

For the sake of anyone new ,where there are nicks in the knives ,the machine is out of proper adjustment. The extra wood left by the gap has in effect made the out feed table too high . The worst offenders are the laminate guys. Not sure why laminate needs to be jointed. Did succeed once in getting a small jointer bought for the stuff ,and I put carbide knives in for them.

[johnny means]

If you mean jointing to get one straight edge, I use my slider. Before I had a slider, I used a long miter slot guided sled. If my slider where gone suddenly, I would now opt for my tracksaw. If your talking about something akin to face jointing, I avoid the need, period.