Horrible jointer technique

[Bob Jones 5443]

Belly belly belly. On every face, every edge, every time I pass wood through my jointer. Jet 6", and if I know anything at all about leveling (I'm even beginning to doubt that!), the tables are parallel and outfeed is level with the blades, which are uniform and sharp.

I press down on the face edge of the board on the outfeed side as it passes the cutters, then I maintain what feels to me as just enough –– not too much –– pressure on the outfeed side as I push across the table from behind (not down) on the end of the infeed side of the board. On the last third of the cut, the tail end of the board comes up off the infeed table, and away from the blades for the last several inches of the cut. So, no cut on the last 5 or 6 inches of the piece! The first several inches are curved into the center like the bottom front of a ski, to form a visible belly across the board.

Same problem with the side edges. Tried it all again with some Douglas fir 2 x 4s. Same. Maddening.

Tables out of parallel, you say.


Starrett 385-24 straight edge propped vertical by blocks designed to make the task hands-free. Slide the Starrett along the outfeed table: perfectly flat (not even a 0.0005" shim will fit under it). Infeed side: same (flat). Same on the inside ("back") and the outside ("front") of the tables.
Slide the straight edge slowly from the infeed toward the outfeed. Raise the infeed until the steel edge just touches the outfeed. Keep sliding out a few inches at a time, placing shims anywhere they might fit. They don't fit. Not even 0.0005" will go under the edge.
Repeat from the outfeed onto the infeed. About halfway through, I can put 0.0015" under the straight edge at the cutterhead end of the infeed. At that position the end of the straight edge (about 5 inches to the left of the cutterhead) is touching the infeed table about halfway down. For the remainder of the rightward slide, the straight edge rides snugly with no gap along the infeed.
Yes, it's a 24-inch straight edge, but I'm pressing down on the back end of the edge as I slide it onto the other table, so the horizontal line is a maintained throughout the process.


So, if anything the tables are forming a minuscule V in the middle, with the low point a maximum of 0.0015" below the "wings." Surely that is not enough to put a belly in every board?

I think I need some hands-on training.

Small silver lining: Since I could not get a straight board on the jointer, I cut my losses when it became clear the front 6 inches were getting close to the final thickness I want for the part. I turned off the jointer and pulled out my Bed Rock No. 607. Several stop-cuts and a cleanup set of shavings later I had the datum face of each board flat.

Discouragement is running high, but so far has avoided despair, if only because I know how to use the Bed Rock. I just wish I could achieve this on the jointer and use the hand planes to clean up the surface.

[Bob Jones 5443]

Can we turn off auto-correct here?

cutterhead = butterhead
outfeed = outfield
infeed = infield

I've had to go back and fix these words every time.

[Andrew Seemann]

How long are the boards you are trying to joint? I've got a 6" Jet myself, and it is maybe good for about a 4 foot board, and that is only if the board is reasonably flat/straight bo begin with.

Do you have a 4 foot level to check the parallelness of the of the beds? The Starrett is a good straight edge, almost overkill for the application, given that the tolerance for the jointer beds is probably measured in hundredths not thousands. What is more important is checking over the overall length, and it is hard to extrapolate that with a 24" length, no matter how high the quality of that length. If your beds are out of whack enough to mess up every board, it should show up with a decent 4' aluminum level.

Also if a board has a bad enough bow in it, it can be hard to pull out with the jointer; it will want to follow the bow. When I get boards like that, I usually mark them with a straight edge and hit them a hand plane first, or bandsaw if it is bad enough.

[Phillip Mitchell]

Sounds like your out feed table is sagging and your straight edge isn’t actually long enough to verify that.

[Kevin Jenness]

Try lowering the outfeed table slightly (.001").

If the tables are flat and coplanar, (and you may need a longer straightedge to establish that), and the knives sharp, then adjusting the outfeed table height is the only other variable. On my jointer with a 4" cutterhead,I get the best results when a straightedge of wood resting on the outfeed table and overhanging the cutterhead is moved about 1/16" by manually rotating the cutterhead.

[peter gagliardi]

I agree with Kevin, outfeed table is too high.

[John K Jordan]

Can we turn off auto-correct here?


Bob, I looked and don't see a specific setting in SMC for auto-correct. However, when I type misspelled words are indicated but nothing ever gets auto-corrected.

Are you using the enhanced editor? Go to Settings and in the left sidebar choose General Settings. Scroll down that page to the Miscellaneous Options at the bottom. If you are using the first editor in the list, "Enhanced Interface - Full WYSIWYG Editing", maybe try switching to the last one, "Standard Editor - Extra formatting controls". Doing this long ago solved a lot of problems for me. I have no idea if that will turn off auto-correct on the forum, but it might be worth a try.

But there is also a general auto-correct setting in Win 10 and other operating systems. Maybe you'll have to change it there. You can ask Sir Google how to turn it off for whatever OS you are using.

JKJ

[Brian Holcombe]

Same as Kevin, adjust this as he explains then try again.

[Robert Hazelwood]

I would try messing with the outfeed table height first, like Kevin suggests. If that doesn't resolve it, then there's probably an issue with the tables but that 24" straight edge is just too short to really tell. I tried to set my tables (total 78" length) with a 36" straight edge and got close but no cigar.

You'd really want at least a 4' straight edge to check a 6" jointer. If you want to buy a 4' Starrett I will not try to dissuade you, but since you have some hand plane skills and a 607 you can make yourself a very accurate straightedge. I'd get a couple of straight grained sticks 4" wide, 1/2" or 3/4" thick, and 4 or 5' long. Clamp them together with their reference edges up and pin them with dowels on each end. Now match-plane the reference edges until you think they are straight, then remove the clamps and dowels and flip one stick onto the other. Check for gaps with feeler gauges. The gaps you find are double the actual error. Repeat until you are satisfied with the error. Should be pretty easy to get under 1 thou.

Now immediately go and check your jointer! These straightedges won't maintain their accuracy all that long. But you can always refresh them by ganging them together, reinserting the dowel pins and taking a few shavings.

Having a pair of these straight edges will allow you to easily check the tables to a much finer degree than you were able to before. I was able to find a small error on mine that had eluded me with the 36" straightedge, and fixing that error removed the small amount of belly I was getting.

[Tom M King]

If the board has a bow in it to start with, are you starting it past the cutterhead for the first pass, and following passes if needed? I always sight the board before starting, and develop a strategy for each board. The jointer could well be off, but you can straighten any length board, on any length jointer, so it has little to do with jointer length.

Do the knives touch a straight piece of wood on the outfeed table when you rotate the cutterhead manually? At first, it sounds like the knives are too low (same as outfeed table too high).

[Derek Cohen]

One other issue to keep an eye on ... although it would be more likely if all the boards you were jointing are the same.

Remeber that a jointer simply follows the line of the board, and if this is curved, then you can simply perpetuate the existing curve if you press down at the toe as it passes the blade. It is relevant to check where the high spots are, and take these down first - the technique is the same whether you are using a hand- or power tool. This is a consideration if all your “affected” boards began a little banana shaped.

Regards from Changi

Derek

[Dan Hahr]

If all is as you stated as far as parallel, technique, etc. you need to lower your out feed table slightly. Dead even with the tops of the knives doesn’t work too well for me. This is a trial and error adjustment. Too small to measure or really see that well. When two boards joint flat and match up perfectly , you’re done.

Dan

[Mark Daily]

Bob, when I joint I don’t put any pressure on the out-feed side of the wood until there is only a foot or so left on the in-feed side. Then I switch over and put pressure on the out-feed side.

Also, are your blades sharp & undamaged? I had a similar problem when the inner portion of my blades wore down and the boards came out with a high spot in the center.

You mentioned you might need some training- lots of videos online to watch. Not as good as in-person but better than nothing.

I’m thinking your technique might be the issue.

[J.R. Rutter]

Kindof sounds like the outfeed table is too high.

You didn't mention how you set your outfeed table relative to the cutterhead. Rather than fuss with indicators and such, I put a straightedge on the outfeed projecting slightly over the cutterhead, then rotate the cutterhead by hand. The knives should lift and pull the straightedge forward a tiny bit. Exactly how much depends on how you use the jointer: Fast roughing to get a flat surface = lower outfeed / more straightedge movement vs slower feed to get a "finished" surface = higher outfeed / minimal straightedge movement.

Also, unless the wood is completely acclimated, skimming the surface off will change the internal pressures and let the surface become more convex (inner core has more moisture than skin) or convcave (inner core is drier than the skin).

[David Utterback]

It is not clear where your downward pressure on the outfeed side is applied. I continue to apply this pressure in an area just beyond the cutting head, switching hands every 6 to 12 inches as the feed is continued. This method sometimes makes feeding the piece difficult and I have to switch to pushing on the back edge of the board. This has worked for me although there are probably several other effective techniques.

[Mel Fulks]

A little less than 2 thousandths too high is all it takes to make the work "climb". That term means ,removing less wood
at end of cut than what was removed at start of cut. If your jointer outfeed table is adjusted by a lever , not a wheel ,they
can be difficult . If the machine has a bolt that serves as a limiter turn just a small bit at a time . Make sure the bolt is
not too loose and turning by vibration.

[Bob Jones 5443]

Andrew,

I was working on 3' boards.

I don't have a 4' straight edge, unless you consider an aluminum level straight. Maybe it is straight enough; I can check it with my 2' Starrett I guess.

But read on; bigger news is coming.

[Bob Jones 5443]

Kevin,

There it is. Last night I searched my way to a Fine Woodworking forum where one of the contributors made a detailed case for lowering the outfeed table so it's ever so slightly below the top dead center of the blade –– just as you suggest. He said the wood straight edge should move 1/8", so that's where I set it (before I've just read your post suggesting 1/16").

Guess what? Two boards, a face and edge each, all ran through the first time with full-length, full-width cuts, and the two boards mate together with no gaps.

Just, wow.

Now I'll hunt for the rationale for this anything-but-obvious-to-me solution.

[Bob Jones 5443]

OK, folks. Too many of you to mention here by name, but almost all of you nailed it. I nudged down the outfeed table to move my test board 1/8" to the right as I rotated the cutterhead by hand. The result was magic, compared to the confounding mess I encountered yesterday. After one pass each, two previously bowed boards mated along their lengths with no gaps.

Could this be the first day of the rest of my life?

My six bucks are paying off handsomely at Sawmill Creek.

[glenn bradley]

Yay! The group-mind wins again! :D

(I deleted my redundant post)

[Tom M King]

Glad it was a simple fix!

[Ole Anderson]

I set my knives just enough above the outfeed table so that when turned slowly by hand, they will catch and drag a straightedge about 1/8". That is how I set them.

Edit, I wrote this before reading your last post!

[Tom M King]

I find it quickest, and easiest, to set the knives flush with the top of the outfeed table, by feel, and then adjust the outfeed table down as needed. No measuring anything. Takes about 20 seconds to set one knife.

[Dan Hahr]

I’m pretty sure the “why” is explained by how the knives will actually compress the wood fibers before they start cutting.
Dan

[Andrew Hughes]

I have a good procedure for setting the outfeed table to the top dead center of the knives. If you have a jointer with a inserts head this work for too.
First lower the out feed so that it is lower then the infeed. Then turn on the machine and cut the edge of the board.It doesn’t have to be a perfectly straight boards but close. When about 3or 4 inches hangs over the out feed table stop and turn off the jointer.
You will know have the exact top of the cutting circle. Raise the outfeed till it barely touches the board that you just jointed.
And enjoy a perfect set up.
Good Luck

[Tom Trees]

Here's a recent video from Jack

https://www.instagram.com/p/B6I6a7DAIzP/?igshid=6tlcaphl54np

[Ray Newman]

Andrew Hughes: great way to do it! Thanks for posting.