Curing twist and hand plane technique

[ByronBlack]

Ok, a couple of questions that are closely related.

I've been squaring up and thicknessing the boads for my greenhouse project. The 500mm length pieces were fine with no problems and was relateively straight forward to do.

However, the 1500mm long pieces are very difficult, in that some have pronounced twist or bow to them and despite trying to correct them by planing of the high spots I seem to just be making the board thinner without succesfully squaring them and removing the twist - i'm using a no.7 jointer for this.

Also i've noticed on these longer boards that i'm introducing a wedge shape across the width of the board despite concentrating in planing equally across the width, i'm finding it very difficult and frustrating to square and thickness these longer pieces, does anyone have some tips or pointers as to handle these, or maybe can point out where I might be going wrong?

 

[RogerS]

Sometimes the wood just does that. It just keeps on moving and twisting as you plane it.

 

[Paul Chapman]

Byron, have you tried scribbling over the boards with a pencil so that you can see that you are in fact planing off the high spots?

Cheers :wink:

Paul

 

[ByronBlack]

Roger - whats the answer to that if the wood does keep moving? Just chop it into smaller lengths and re-use for another project?

Paul - i've tried the pencil marks, and they do come off, but then i'm always left with one end thinner than the other, I think the actual length of wood is what is giving me the problem, either that or maybe my bench isn't flat - would that make a huge difference?

 

[Paul Chapman]

It's difficult to suggest what's going wrong from your description. If your bench isn't flat, that's certainly not going to help. If the bench is just a little bit out, you could try packing with thin pieces of card under the workpiece. However it sounds as if there might be something wrong with your technique. Did you see MarcW's illustrated description of his method for planing a board in this thread https://www.ukworkshop.co.uk/forums/view ... ht=#166617 The board that he's starting with might be a bit straighter and flatter than yours, but the principle is the same. Reading through his description and looking at his photos might give you some clues as to where you are going wrong.

Sorry I can't be more helpful, but if you try to analyse the problem methodically you should be able to come up with what's going wrong.

Cheers :wink:

Paul

 

[RogerS]

Roger - whats the answer to that if the wood does keep moving? Just chop it into smaller lengths and re-use for another project?

'fraid so. Or firewood as in my case :evil:

 

[MikeW]

Another option to having a very flat bench, at least for smaller boards, is a
planing board.

One thing which often helps is removing material as one goes from both sides. Wood is in tension, some boards more than others. Remove too much at one time from one side and the board may end up in a worse state than if material is removed a bit at a time from both.

Take care, Mike

 

[Paul Kierstead]

On the twist and bow: Even if your bench is dead flat, long boards can be difficult. One of the big problems is that as you press down, the board bows down as well, so you take off an even shaving instead of knocking off the high bits. I have found 3 general solutions:

1) Shims under the board. I shim underneath so that the board is steady. You must shim fairly accurately; if you over shim you will create an opposite twist/bow. This makes the board "steady" and lets you flatten one side.

2) Careful targetted planing. This require some practice to plane just the high spots. YMMV.

3) Plane one side very roughly flat using (2), flip over, and plane the other side flat. Note the two sides may not end up parallel. I do method 2 quite roughtly; mostly just enough to have the board lie reasonably flat. I use a jack or scrub to get there. When I flip the board over, it now touches the (hopefully flat) bench evenly, so the planing pressure won't change its shape. This is the method I use on heavily warped boards.

If you want to cheat, you can do (2) roughly and run it through a thickness planer. Say you flatten side (A). It is flat, but quite rough (scalloped). Put through the thickness planer with side A down until B is thoroughly planed, flip over run through with B down until A is smooth (well, as smooth as it will get in a thickness planer). This method works well and doesn't take much time, but is a hybrid hand/power method.

 

[ByronBlack]

Thank for all the replies, it definitly gives me something to think about! I'm now left wondering however is hand-stock preperation just too big a job for amount of meterage I have to get through? I think i'll head back out, sharpen up and try some of the tips mentioned to see how I get on.

 

[Anonymous]

I'd say same as Paul.
I'd add - a flat bench not much help with a bent board as you might have to shim it in any case. Basic rule with stock is to set aside the very bendy bits for shorter lengths.
Boning rods useful (essential?) and thick pencil marks so you can see where you've been.
Don't rely on the plane or the bench but use your eyes to find the high points by looking down the length.

cheers
Jacob

 

[Colin C]

I'd say same as Paul.
I'd add - a flat bench not much help with a bent board as you might have to shim it in any case. Basic rule with stock is to set aside the very bendy bits for shorter lengths.
Boning rods useful (essential?) and thick pencil marks so you can see where you've been.
Don't rely on the plane or the bench but use your eyes to find the high points by looking down the length.

cheers
Jacob

I have two things to add.

It can also be helpful to use crayons in stead of a pencil ( I got a bag of 30 from the £1 shop, with lots of colours ) and you might be using more pressure at the end of the cut, than the start.

It might not seem like much but after a few cuts it starts to make a difference.

 

[Alf]

Boning rods

Winding sticks?

 

[Paul Kierstead]

Boning rods

Winding sticks?

It would seem not. I am not sure how these work for cabinetry sized objects though; might be interesting to muck around with.

 

[David C]

Long stuff very time consuming.

Bowed and twisted stuff best rejected or used short.

Final thought how much influence is the bow twist going to have at glue up stage, or in the final job. Sometimes the clamping will straighten things up a bit.

Hand planing of lots of metres probably not a viable option.

David

 

[Anonymous]

Boning rods

Winding sticks?

It would seem not. I am not sure how these work for cabinetry sized objects though; might be interesting to muck around with.

Er, winding sticks then if you insist. SO pedantic :roll:

cheers
Jacob

 

[ByronBlack]

Hi guy's, appreciate your comments.

Colin - I think crayons/chalk might be a good idea, even though i'm using fairly soft carpentry pencils, it's a little difficult seeing it against the shine of the maranti - I think I need more natural light in the shop.

After re-reading through Marcs pictorial of Mr C's technique I decided to have a go and follow it through with some of the more wedged shaped smaller pieces to see how I get on, and it works like a charm! Even though my blade isn't very cambered I managed to follow the technique quite closely. The piece is by no means perfect but I managed to remove some of the wind and the wedgeness - just got to try and transfer the skill to the longer lengths if possible.

David - I think with regards to your question about the bowed/twisted piece in the glue-up, seeing as they are only 44mm square boards and will be used for what is essentially a relatively agricultural piece I might just get away with it.

I was thinking of using the twisted piece as the rail as opposed to the stile, and when I cut the tenons - make sure these are square to the appropriate mortice, so the twist shouldn't in effect have a bearing on the overall glue-up (I read about that on a google search). However, in practice would the twist not continue and put pressure on the joint?

P.S I received today a copy of your furniture-making techniques volume 2 (vol 1 in the post) and thought it was excellent and asnwered many questions i've had in regards to saws, plane blades, (I really liked Grete's drink cabinet..very smart).

 

[Paul Chapman]

will be used for what is essentially a relatively agricultural piece I might just get away with it.

Byron, I think this is perhaps the crux of the matter. For something like a greenhouse, the precision required is not the same as it would be for a fine piece of cabinet making. In fact, given that it will be subject to extremes of weather, the wood is most likely going to move quite a bit anyway once it's up. If I were making something like a greenhouse, I would concentrate on ensuring that the joints were sound but would be quite happy with a bit of tolerance in other aspects of the construction, provided that the finished job looked right.

Cheers :wink:

Paul

 

[David C]

Byron,

Delighted you enjoyed my book. Greta's cabinet is a big favorite!

I have included most of the common issues & techniques which crop up for furniture makers in the beginning, as this is my specialist area.

best wishes,
David Charlesworth

 

[Alf]

Er, winding sticks then if you insist. SO pedantic :roll:

Not pedantic, just that we probably all know what the heck a winding stick is whereas my Every Girl's Book Of Building Site Knowledge is still on back order. :wink:

Cheers, Alf

 

[Anonymous]

Hazards of using winding strips no.96.
Avoid banging head too hard against the workpiece as this can induce coma

or Misuse of winding strips can kill. Always wear a helmet, or just say "no thank you"

cheers
Jacob