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sparkus88

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Hi I've been having problems with pine bowing after I've put it through my P/T. Example I took some wood from 21mm to 15mm, finished size will be 13mm yesterday left it over night but when I came back to it today it had bowed. So much so that it will be thinner than the required 13mm once its gone through the P/T again. The wood isn't the best quailty but it should be dry enough its been it the spare bedroom for about 2-3 months. Any ideas.
 

marcros

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did you remove material from both sides, so the 15mm was the middle of the 21mm, or did you just remove from one face?
 

9fingers

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sparkus88":1t5t8xsa said:
faced then through the thicknesser
That is almost certainly the problem. Once you have a flat face from the jointer, then use the thicknesser until it is catting all over the opposite face. Then plane alternate faces as you thickness to final size.

Bob
 

RogerS

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You don't even need to bother with getting one side completely planed either. As long as you have a clean line down part of the board to give support, you can thickness the other side, then turn back to the first side and carry on as Bob suggests.

Can't claim credit for this tip. I read it in an issue of BW and works very well.
 

9fingers

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Sounds a bit risky to me Roger - I suppose it depends on the spacing of the rollers in the thicknesser.

Bob
 

RogerS

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Spacing doesn't come into it. As long as you have a flat surface somewhere down the length you don't need to plane all the side. Think of a board that is cupped down the length, for example. You plane it concave side down and so you'll gradually start planing off the two high spots on either side. Once you've got both high spots planed, it doesn't matter if the hollow is still there. You put it on the thicknesser and start thicknessing the convex side, flip over do more on the concave side. Let the machine do the work.

Try it! Obviously won't work for very thin boards.
 

Digit

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In addition don't prop lengths of timber at an angle and don't lay boards flat on one face, either of these moves can promote bowing.

Roy.
 

sparkus88

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Ok I seem to have been doing a few things wrong. After facing I took the rest of the material off the other side and I've been keeping the boards leaning against a wall. I did the alternative thing yesterday and was very little movement over night.
 

Digit

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We all learn the hard way I'm afraid.

Roy.
 

Benchwayze

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When you use the kind of timber I sometimes have to buy; and you have to sponge down the planer with white spirit to get rid of 'maple-syrup', it doesn't matter what you do. Boards bend like withes. But that''s me being a cheapskate!

Best of luck Sparkus.

John :)
 

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