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Why is jointing so hard?

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Forum topic by bgilb posted 03-18-2019 05:11 AM 516 views 0 times favorited 7 replies Add to Favorites Watch
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bgilb

93 posts in 3385 days


03-18-2019 05:11 AM

I can’t seem to figure out how to joint consistently. It’s kind of like golf and you think you discover something to take 5 strokes off your score and then you have an outing where you snap your putter half.

Here is the only thing that works enough to give me so so results.

Basically almost no pressure when face jointing with the bow down or concave side down. I have to take like 10 passes that are incredibly light. Like 1/128” per pass lol. I also have to alternate end over end or the board starts becoming wedge shaped and one spot never seems to get jointed.

I think I get them flat and then after planing some are pretty flat and others are as bad as 1/16” bow over 40” or so. All the boards where 40” or so and my jointer bed is 48”

I’ve double checked alignment and everything seems fine. If I joint something that’s shorter like 25” or less it seems pretty much flat but it could be the error is smaller with those lengths.

Does it always feel impossible like this?

I’ve probably put 300 feet of wood through the jointer.


7 replies so far

View CaptainKlutz's profile

CaptainKlutz

1083 posts in 1820 days


#1 posted 03-18-2019 07:13 AM

IME – There are 1 key to using jointer with success:

==> Reading the grain.
Why?
This is quickest way to see why wood moved, and best milling direction to fix it.

Always ask:
Does the board have any twist?
About only time I find jointing difficult, is when the board is twisted, or grain direction changes that result in something looking like a potato chip. It means the board has unequal stress. A twisted board is never going to behave, before or after milling.

Only proper course of action is get a new board, or cut the board into shorter lengths where the feature that started the twist is in cut off zone. The shorter pieces will be much easier to get flat.

You mention that ‘one spot never seems to get jointed”; if board is not twisted, this likely means that cutter/table heights are not set up properly, or your feeding technique is in error?

Even if you are properly reading the grain, The jointer takes some time to learn and make it work for you; and not against you. There are a ton of ‘how to’ threads in Lj, WWW, and major magazines have detailed articles with technique/tips/tricks. Will not repost all them again.
Try these references:
https://www.lumberjocks.com/topics/17713 or

https://www.lumberjocks.com/search_results?cx=017914489645407774653%3Agwwk-zif3wk&cof=FORID%3A9&safe=high&q=jointing+tricks&sa=Search&siteurl=https%3A%2F%2Fwww.lumberjocks.com%2Ftopics%2F17713

https://www.woodmagazine.com/woodworking-tips/techniques/joinery/6-jointer-pointers
https://www.wwgoa.com/article/master-the-jointer/

PS – One tip that helps with jointing is to set board on flat surface. Next mark all height imperfections (I use colored caulk). Then pick side with least amount of deflection, and use a long straight edge and pencil to mark side of board showing what will be left after you get the face flat. Goal is not to mill every sq inch of the face, only to remove the high spots needed to get it flat. This help immensely to visualize where wood needs to be removed. Remember, only after you one flat face can you edge joint.

Cheers!

-- I'm an engineer not a woodworker, but I can randomly find useful tools and furniture inside a pile of lumber!

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Carlos510

75 posts in 698 days


#2 posted 03-18-2019 12:11 PM

I agree the condition of the wood you are using and how you handle it may be part of the problem. You said you checked the tables but if this is happening consistently I would double check how parallel your outfeed table is to the infeed table. What you describe would indicate that it is not. Also the height of the outfeed table may not be in perfect alignment with your knife edges at there highest point. I have an article on my blog that will help you set the knives and includes a nice jig to help you out. http://hobbyworkshopprojects.blogspot.com/2019/02/setting-jointer-knives.html

-- From popular rap:"If time is money, then I need a loan." Carlos B., http://www.hobbyworkshopprojects.blogspot.com/

View Robert's profile

Robert

3343 posts in 1807 days


#3 posted 03-18-2019 12:52 PM


Basically almost no pressure when face jointing with the bow down or concave side down.

Sounds like you’re doing it right. Yes, double check your table alignments.

FWIW, I’ve run many 1000’s of feet and I’ve found longer boards can have a built in spring back due to internal stress. These you can never really get them perfectly flat and trying to do so will only result in a board too thin that ends up in the scrap bin.

Depending on the application, a slight amount of bow might not matter. For example, with a panel glue, I don’t fret it much.

But with a long stile for a door, for example, sometimes I have to give up on perfection and resort to splining else I run of stock!

-- Everything is a prototype thats why its one of a kind!!

View TungOil's profile

TungOil

1163 posts in 821 days


#4 posted 03-19-2019 02:13 AM

The wedge shape you are describing tells me you need to double check your jointer set up. Also, you should be putting all of your downward pressure on the outfeed table, not the infeed table or you will not get flat boards.

-- The optimist says "the glass is half full". The pessimist says "the glass is half empty". The engineer says "the glass is twice as big as it needs to be"

View Craftsman on the lake's profile

Craftsman on the lake

2932 posts in 3764 days


#5 posted 03-19-2019 02:28 AM

And with your standard 6” (and thus shorter) jointers long boards are difficult to do. Shorter pieces that where the bow is more condensed work good. A longer board is fairly straight for the part that is on the jointer table, but considering the entire length, it can have a substantial bow and the jointer doesn’t see it.

-- The smell of wood, coffee in the cup, the wife let's me do my thing, the lake is peaceful.

View MikeDilday's profile

MikeDilday

186 posts in 785 days


#6 posted 03-19-2019 02:39 AM

Actually I always but the bow side UP so the two ends are touching the planer deck. Then I keep pressure on tthe front or outbound side of the board so it keeps on the outfeed table. It works great for me.

-- Michael Dilday, Suffolk, Va.

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Holbs

2194 posts in 2355 days


#7 posted 03-19-2019 03:25 AM

I know your pain. Been using a jointer for years and still run into the same problem your spoke of sometimes. My infeed/outfeed tables are coplaner, fence is 90 degrees.
I watch videos of people using a jointer using various methods and their pieces come out as they should. Sometimes, not so in my shop! I see people press down on the infeed table to get that grip to slide the piece forward, defeating what I thought of no downward pressure. I usually end up pushing the piece from the rear horizontally to get started over the cutterhead and then switch to downward pressure on the outfeed.

But I think the big booboo is that it’s been 2 years maybe since adjusting knife height. I checked and they were out of whack by 0.015-0.020 in places HIGHER than my outfeed table which would cause the rear end of the piece get shaved too much causing taper.
And I do know…when you joint a face or edge and there is a knot, it has a good possibility of disrupting the joint process.

-- The Carpenter Bee is derived from the Ancient Greek word wood-cutter "xylokopos/ξυλοκὀπος"

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