Thread: straightening long length wood

Originally Posted by Timbale

Hi all,

I am a beginner, and i need some.
How can i straighten 5 meter long length pine (90mm x 45mm), when i am buying them they are not straight.
Some one advised me to buy a planer and a thicknesser to straighten them.
My question is will i get the accuracy if i go through a planer and a thicknesser.

Please help.

Cheers
Tim

Do you mean that the timber is not smooth ie: it has very fine grooves on all 4 sides and a very slight radius on the 4 edges, if that is the case, what you are referring to is 'dressing' the timber or as known in the trade DAR (dressed all round) then the planer and thickness-er will be ok
If you are referring to it not being straight ie: it is bowed or slightly curved in its length, then the tools described will not fix it.
It would help if you can explain what the end use for the timber is and will it still be 5.0m long when finished (I suspect not though)

Originally Posted by Timbale

I am a beginner, and i need some.
How can i straighten 5 meter long length pine (90mm x 45mm), when i am buying them they are not straight.
Some one advised me to buy a planer and a thicknesser to straighten them.
My question is will i get the accuracy if i go through a planer and a thicknesser.

First some questions.
What are you building that needs 5 m long straight lengths? Most 5 m long lengths are not dead straight and they don't need to be because of they way they are used in structures that are fixed and hold themselves together straight.
and
Which way are they not straight? Across the grain, or along the grain and if the later is it bow or twist?
To completely straighten 5 m lengths may also waste so much wood that it may not be possible to do it and leave any worthwhile wood behind.
A general guide is it is very difficult to completely straighten along the grain a length any longer than than about twice the length of any planer that is used so in this case you will need 2.5m long planer which will not be cheap.

You won't

Thanks for your reply guys.

I am buying 90x45 treated pine and then making them into half from the middle, so then i have two 5 mtrs length of 45x45 mm.

Then i am cutting them in 4 pieces to make a square frame.
When i finish them some sides are straight but some sides are not sitting straight on the floor, cause they are little warp.

so what i want is good straight finish on my frames.

What do you suggest guys?

Originally Posted by Timbale

Thanks for your reply guys.

I am buying 90x45 treated pine and then making them into half from the middle, so then i have two 5 mtrs length of 45x45 mm.

Then i am cutting them in 4 pieces to make a square frame.
When i finish them some sides are straight but some sides are not sitting straight on the floor, cause they are little warp.

so what i want is good straight finish on my frames.

What do you suggest guys?

Ok, so you are ripping them in 1/2, presumably with a circular power saw.
2 things you can do. use a electric planer to dress the newly cut edge or better still, run the timber through a thickness-er.
Are you using the ripping guide in the saw, this will minimize the variation in the cut.
Dont for get to wear a dust mask and safety goggles when cutting treated pine. My boss from my apprenticeship days lost his son to cancer as a result of treated pine sawdust getting in his eyes and lodging in the back of the eye socket.
And dont burn the off cuts in a B-B-Q or fireplace, the smoke and fumes are lethal.

Originally Posted by Timbale

Thanks for your reply guys.

I am buying 90x45 treated pine and then making them into half from the middle, so then i have two 5 mtrs length of 45x45 mm.

Then i am cutting them in 4 pieces to make a square frame.
When i finish them some sides are straight but some sides are not sitting straight on the floor, cause they are little warp.

So the frames are 2.5 x 2.5 m?

BTW you cannot rip a 90 x 45 into 2 pieces of 45 x 45 mm. The ripping process will required at least 3 mm so the final will be at best 45 x 43.5 mm

So you don't need 5 m of straight wood, you need 4 length of 2.5 m of straight wood - there is a difference in this and you could straighten the 2.5 m lengths with a more normal 1.2 m long planer or even with a hand plane. The degree of warp will determine the final cross section but my guess is it will be less than 40 x 40.

If it is badly warped it may simply not be possible to straighten them.

Originally Posted by Timbale

Thanks for your reply guys.

I am buying 90x45 treated pine and then making them into half from the middle, so then i have two 5 mtrs length of 45x45 mm.

Then i am cutting them in 4 pieces to make a square frame.
When i finish them some sides are straight but some sides are not sitting straight on the floor, cause they are little warp.

so what i want is good straight finish on my frames.

What do you suggest guys?

your better option is to
1) cut the 5m length in half to get two 2.5m lengths
2) then cut them down the middle to get four lengths, 45 x 43.5 x 2.5m long
3) then decide how out of square the pieces are

depending on the what you are trying to build -- treated pine implies a framed opening in a building -- you may be better off buying 2.7m lengths. Also, depending on waht you're building, the frame may pull itself square when assembled and attached to the rest of the wall.

Sometimes when you rip pine it will release tensions that will add all the timber movements you can name, bow, warp, spring and even over 2.5m it is possible to be so much that you will have only a very small dimensioned piece by the time you have something straight and square again. And even as you machine it it can continue to move. As Ian suggested, if it is possible to anchor/affix/straighten the frame in situ that would be best. If not and it is only a small deviation, I would go at the assembled frame with a handplane or electric plane until it is sitting flat on the floor. Of course it may still move again over coming days, especially if outside. Putting it through a thicknesser will tidy up a rough sawn edge but it will not straighten and to joint it first - see explanation above. Another option might be to use recycled hardwood (some of which can also do the same as pine but should be less of a problem) Make sure it is a durable hardwood if out in the weather (ironbark, spotted gum are two easily identifiable). Also Merbau or Kwila would be good and supremely stable (but prone to leach stain which would need to be addressed if in a sensitive area - you can leach the wood completely by soaking it in changes of water in a trough made of builders plastic for several weeks. One maker of fine kwila outdoor furniture use this method to eliminate staining problems)

In my experience it is a complete waste of time straightening a piece of T/P and expecting it to stay that way - especially as mic-d says if it is outside, and I can't think of why you'd want to use T/P if it's not outside.

T/P is usually quite wet when you get it and it will warp as it dries out. I have found that when building with the stuff, you either live with the fact that it will move, or you build in such a way that it's affects are minimised - by anchoring to other more stable structures for example. I have made some lattice panel frames recently from 90x18 decking which stay relatively straight by virtue of the fact that I made the lattice panels a neat fit and the panels are nailed to the frames.

There's no way that you can rip a 90x45 in half and expect it to stay straight. You may have more luck leaving it 90x45 and trying to straighten it after cutting to length - and even then you will probably lose a good 5 or 10mm in size. The extra thickness may keep the long sides of the frame straight, but a 200mm x 75mm sleeper will warp easily so don't count on it.

If you really want perfectly straight frames, you're going to need to use kiln-dried hardwood as mic-d suggests and it will most likely have to be painted. Blackbutt is another good timber which I have used for handrails. But the price will be at least double what you pay for T/P.

T/P is a 'near enough' building product in my opinion, not a material for craftsman-like work

Thank you all for your suggestions.

Greatly appreciated.

Cheers
Tim