What is going wrong with my jointer?

[Josh Davidson]

It seems like every wide board that I buy turns into a wedge once I'm finished jointing it. At first I thought maybe it was the stock I was picking out, but now I'm not so sure. I double checked the adjustments on my tables and everything seems to be pretty good, so I'm quite perplexed. Here's an example of a board that that I just face jointed: https://imgur.com/a/TDgiOF7

[Andrew More]

It's hard to tell without seeing what you're doing in person, but a jointer only make a face flat, it does NOT make it parallel, which is what a thickness planer does. This is because the reference surface and the knives are in the same plane. A thickness planer does not have this issue, because the knives and the reference surface are parallel to each other.

So that being said, it's very possible to produce a variety of shapes with one flat face, or two flat faces next to each other, at an angle.

When you insert the board into the machine, you need to think about what you want to have cut by the blade, and push down accordingly. It also helps to work with shorter pieces, since they're less likely to be so far out of true that you cut big portions off.

[Andrew More]

Here is a video that goes further into this.
https://www.youtube.com/watch?v=5af_yZQHo8k

[Andrew Hughes]

That’s exactly how a jointer will cut when the knives are set high on one side. For instance if it’s just 1/64 higher two passes add up to 1/32 .
Your solution is to reset the knives on the side that’s cutting more.
If you have a insert head you will have to shim the low side of the head under the bearing block up.
Good Luck

[Mike Kees]

That’s exactly how a jointer will cut when the knives are set high on one side. For instance if it’s just 1/64 higher two passes add up to 1/32 .
Your solution is to reset the knives on the side that’s cutting more.
If you have a insert head you will have to shim the low side of the head under the bearing block up.
Good Luck
I agree with this. For sure it is the first thing to check.

[michael dilday]

Blades are not on the same plane as the outfeed table IMO.

[johnny means]

Joint frown side down.

[glenn bradley]

Has that example been jointed on both sides? Remember, jointers make one side flat, planers make the other side parallel to that.

[Mike Kees]

Here is a video that goes further into this.
https://www.youtube.com/watch?v=5af_yZQHo8k
When I first posted yesterday I had not seen the OP's original picture,now that I have ,I believe that Andrew More and Glenn are on the right track. That being said I would still check that your knives /cutterhead are lined up properly to the outfeed table of your jointer. The link Andrew posted is excellent to figure out what a jointer does and does not do.

[Al Launier]

I had the same problem years ago & had to shim the gibs to have co-planar tables & cutter head. Prior to that my jointer would take a board that was reasonably uniform in thickness with no twist & produce a "clapboard". I even had a long time competent woodworker try my jointer & he had the same results.

I'd like to recommend a book that I found very helpful in maintaining my equipment & was used to guide me through the shimming of my jointer. It's "Care and Repair of Shop Machines" authored by John White.

[Steve Jenkins]

Where are you located? Maybe someone is close enough to stop by and give you a hand.

[Derek Arita]

How many passes to get to that point? That looks extreme. Is that a jointer/planer?

[Steve Jenkins]

Josh, just curious if you solved the jointer problem.

[Mike Kees]

Josh, just curious if you solved the jointer problem.
Yeah me too.

[Derek Arita]

This guy has to be yanking us all. Look at that board...that's ridiculous! I don't think I could do that if I tried. I think Josh is looking for a reaction, not a solution. If I'm wrong, sorry.

[Matt Day]

have to agree with Derek. I don't know what's going on with this kind of stuff lately.

[glenn bradley]

have to agree with Derek. I don't know what's going on with this kind of stuff lately.


I can answer that. Since the early 2000's the internet has been involved in a screaming downhill race into the toilet. Instead of the incredible information resource and sharing machine we envisioned it has become a global marketing tool, a global city with way too many slums and seedy quarters . . .

. . . did I say that out loud? :D

[Al Launier]

This guy has to be yanking us all. Look at that board...that's ridiculous! I don't think I could do that if I tried. I think Josh is looking for a reaction, not a solution. If I'm wrong, sorry.
Having had the same problem, and then having an experienced woodworker who had his own jointer having the same results on my jointer, I believe him. Shimming to co-planar the tables solved the problem.

The "clapboards" I made looked very similar to the photo he posted above. In fact, Glenn might recall me having that same problem and then congratulating me for the "fix". Always appreciated Glenn's comments.