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I've never had a problem planing boards before, but planing the edge of some of that multi-laminated 8mm plywood is giving me a problem! Every time I run some through, the edge comes out curved. What's with that?
 

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Either of 2 things or both

Machine set-up or technique.

See post 11 below.

If you start with a curved board, more than 1/8" hollow on edge, chances are you'll end up the same way. So, joint in a little from each end then sight the board. Keep at it until your sighting tells you it's straight. Then run a few light passes and you should be OK.

If not then the set-up is off. Assuming both your tables are adjustable, make certain the outfeed table is just at the highest peak of the blade rotation, no more, no less. Then raise the infeed to the same height and check across both tables with known straight edge, or a 48" aluminum level. It should all level out and be in one plane.. If not more problems .....I gotta feed the dog now. Good luck, Best Wishes, Merry Christmas! :laughing: bill

BTW this is post number 4,444 maybe no one will notice...
 

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Machine set-up or technique.
If you start with a curved board, more than 1/8" hollow on edge, chances are you'll end up the same way. So, joint in a little from each end then sight the board. Keep at it until your sighting tells you it's straight. Then run a few light passes and you should be OK.

If not then the set-up is off. Assuming both your tables are adjustable, make certain the outfeed table is just at the highest peak of the blade rotation, no less. Then raise the infeed to the same height and check across both tables with known straight edge, or a 48" aluminum level. It should all level out and be in one plane.. If not more problems .....I gotta feed the dog now. Good luck, Best Wishes, Merry Christmas! :laughing: bill

BTW this is post number 4,444 maybe no one will notice...
Why does the post counter to the left say 4,448?

George
 

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Machine set-up or technique.
If you start with a curved board, more than 1/8" hollow on edge, chances are you'll end up the same way. So, joint in a little from each end then sight the board. Keep at it until your sighting tells you it's straight. Then run a few light passes and you should be OK.

If not then the set-up is off. Assuming both your tables are adjustable, make certain the outfeed table is just at the highest peak of the blade rotation, no less. Then raise the infeed to the same height and check across both tables with known straight edge, or a 48" aluminum level. It should all level out and be in one plane.. If not more problems .....I gotta feed the dog now. Good luck, Best Wishes, Merry Christmas! :laughing: bill

BTW this is post number 4,444 maybe no one will notice...
Is it only this specific plywood? Or do you have a problem with all ply wood?

Personally I find plywood difficult to run through a jointer.

George
 

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He's running the plywood through a jointer, to square an edge.
Woodnthings, I've never heard of taking a little off at each end to get it closer. Now I've learned another trick.
 

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He's running the plywood through a jointer, to square an edge.
Woodnthings, I've never heard of taking a little off at each end to get it closer. Now I've learned another trick.
Rick if it may help to think of a jointer like a giant hand plane rather than a one step, one shot, one pass wonder machine.
Your sighting abilities come into play right from the start...cup? bow?...twist?....Then use the jointer to remove all the stock that is offensive, especially if flipping end for end will reduce the number of passes, and it will once you get the hang of it. Keep planing/jointing part way in then lifting the work piece off, until you get as close by eye then use firm down pressure on the outfeed table to flatten (surface) or straighten (edge) the stock.

I've never gotten used to calling a Jointer a "planer" since you really are referring to a "thickness planer" you've got every one confused. This happens a lot here and the terms do make a difference when asking a question.
They have different meanings in the UK for example, where
a jointer/planer means a jointer over here.

Having said all that the jointer can indeed be used as a planer, but a planer can't be used as a jointer .:eek: :no::yes: bill


And why they cut CURVES:
 
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i too never use the joiner as a planer, but i will use the planer as a joiner. you just have to make sure you start of with a true 90 on the planer table
 

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Jack did you watch the videos?

The jointer makes one straight and flat surface or edge, if all goes well.:smile: Then you can make one or both edges square to that surface.
The planer makes that flat and straight surface, which now is resting on the bed of the planer, a uniform thickness, since the cutters are above and will remove anything in their way.
You can't make 2 opposite surfaces parallel, or a uniform thickness on a jointer. They can only be made straight and flat and "square" to one another and with no reference to the opposite surface. If you've flattened one surface, then you can edge joint both edges. But the remaining surface will not be a uniform thickness to the original. It might be square to it, but not uniform thickness.

You can use a jointer as a planer but not conversely. The videos show and explain why much better than I did above. ;) bill

 
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after your post i watched it, and agree for the most part. i dont own a joiner they take up too much room in the shop and there are other tools that can be used. i always do my large surface first, via the surface planer, then i use an electric hand planer for one edge, then table saw to square ( cut a hair over what i need the cleaned up with a pass or two again with the electric hand plane. thats always worked for me.

or after using my thickness planer, if the board is less than 6" wide, ill cut on the table saw to square one edge, put that edge one the table side of the planer, and run it, flip it do the other side and done. normaly i dont do this if the board is thiner than 1/2 in.
 

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Discussion Starter #15
Thanks for all the comments, guys! I already had a straight and parallel (?) edge after cutting on the TS, but just wanted to clean the edge to joint it at 90 degrees with another board for a fence. Every time I would run this stuff through, I end up with a board that looks like a bow, as in bow & arrow. The more I would run it through, the more it would curve! I just went to the TS and made a fine cut and left it at that! Just can't figure out why that particular piece won't come out straight. Everything is set up right, as any other board I've ever run through came out ok.
 

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Now come on!

You're gonna tell us that one piece of plywood is smart enough all by itself to come out curved? That makes no sense. I'd look for jointer knives that aren't parallel to the cutterhead, one side of the bed that is twisted, or a bed that is higher on one side than the other WRT to knives....somethin' ain't right. :thumbdown:
So, if you take a relatively straight 1 x 6 about 4' long and joint it,using the same location on the cutterhead, it will come out as straight as you can measure it, but not the same size plywood?
Beats me.:eek: bill
 

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If your blades are dull even a little especially with plywood. The plywood likes to jump up or ride up on the knives instead of sitting flat on the off feed side it will ride up on the knives. The way the plywood grains are it has a hard density like a knot. Try a little extra pressure than normal on the off feed side.
 

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Yeh, ok, I have a problem! Have to check everything out! Ran a poplar board through last night and had the same thing! Ends measure the same, but the middle came out about a 1/16 wider! So the plywood isn't the only smart one out there! :laughing:
 

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i too never use the joiner as a planer, but i will use the planer as a joiner. you just have to make sure you start of with a true 90 on the planer table
Really you should run a rough-cut board through a jointer to get a flat face, which you later use as a ref in the planer. I believe a lot of people skip this step as they think the rough-cut lumber is flat enough. However on crappy-cut lumber you would have to run it through the jointer first.
 

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Yeh, ok, I have a problem! Have to check everything out! Ran a poplar board through last night and had the same thing! Ends measure the same, but the middle came out about a 1/16 wider! So the plywood isn't the only smart one out there! :laughing:
How much of each end is okay? Just the first inch or so?
 
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