Planing a board flat - Is there literally no light when testing with a straight edge?

[paulrbarnard]

Out of twist -- crucially important. Dead flat to the point of no light showing when testing length and width -- much less important.

It's possible for a panel to pass the light test, and still be in twist, if so it won't pass the light test when tested diagonally.

Good point. Spinning the straight edge around can help with identifying this situation. I use winding sticks as part of the flattening process which I find to be the best approach. You can simply look down the board but the winding sticks exaggerates the twist.

 

[Pabs]

I'd recommend buying the book by wearing 'the essential woodworker', his method is the best I have found yet, basically you need winding sticks, and remove all twist but it also must be flat length ways and across before marking it with a face symbol, then you can do the edge and from there all the other marking out, if you're doing something like dovetails it is really important to get the boards flat where two boards meet and also edges dead square with a shooting board or you'll never get perfect joinery, it's even more important with mitred dovetails.

I have this book on the recommendation of the good folks here and between this and the youtube videos manage to get stuff square now but it did take a while of dedicated practice to get there!

edit also I have winding sticks which I think are pretty essential for this process and can double as straight edges

 

[Trafalgar]

Good point. Spinning the straight edge around can help with identifying this situation. I use winding sticks as part of the flattening process which I find to be the best approach. You can simply look down the board but the winding sticks exaggerates the twist.

I have this book on the recommendation of the good folks here and between this and the youtube videos manage to get stuff square now but it did take a while of dedicated practice to get there!

edit also I have winding sticks which I think are pretty essential for this process and can double as straight edges

Out-of-wind, relatively flat -- both have to pretty much be done under the constraints of planned thickness of the workpiece. You aren't, of course, just endlessly planing test boards and calling it woodworking. They have to go into a project. There is room for discrepancies in the finished thicknesses of certain workpieces, but not a lot.

 

[Pabs]

Out-of-wind, relatively flat -- both have to pretty much be done under the constraints of planned thickness of the workpiece. You aren't, of course, just endlessly planing test boards and calling it woodworking. They have to go into a project. There is room for discrepancies in the finished thicknesses of certain workpieces, but not a lot.

I'd never pass on endless planing of things.
or practice for that matter

this is 10months of practice with a few projects along the way

 

[Trafalgar]

Back to the subject at hand. No, you don't have to flatten until there is literally no light. The workpiece MUST be out of winding, and then relatively free from other warping, all within the planned thickness of the workpiece.

Learning to lay out facets and plane to the lines -- I think they still do this at Barnsley in the first couple of weeks. Then they move on.

 

[Jacob]

Back to the subject at hand. No, you don't have to flatten until there is literally no light. The workpiece MUST be out of winding, and then relatively free from other warping, all within the planned thickness of the workpiece.

Learning to lay out facets and plane to the lines -- I think they still do this at Barnsley in the first couple of weeks. Then they move on.

If you can see light you need to check the straightedge too. How are you going to do that?
Straight edges aren't necessary except winding sticks for twist and flatness across the width.
Just use your eyes.
If it's about fitting things together like boards for a table top you get them as straight and square as you can and then fit them to each other rather than each separately to a straight edge.
Sometimes other things not perfect can get pulled into straightness when the whole thing is constructed

 

[Trafalgar]

Well, you flip a straightedge to check it -- just like you do a square.

That said, I agee with everything else you wrote. A reasonably flat workbench top is flat enough as a reference surface. The edge of 2, 4, or 6 foot aluminum levels are as well.

 

[Jacob]

Well, you flip a straightedge to check it -- just like you do a square.

er - really? OK for checking a square but not sure how you'd check a straightedge, except with another one, or two to be precise! See Whitworth and the 3 plate method.

 

[Trafalgar]

Tap two brads in a workbench or board -- distance between brads is almost as long as the straighedge. These can be oriented any way you like. Two points always make a straight line.

Register straightedge to the brads and draw a line between the brads. Flip (not end-for-end) and draw another line. Look at the lines. If the distance between the two lines is consistent to your eye -- it's straight enough for woodworking.

 

[Jacob]

Tap two brads in a workbench or board -- distance between brads is almost as long as the straighedge. These can be oriented any way you like. Two points always make a straight line.

Register straightedge to the brads and draw a line between the brads. Flip (not end-for-end) and draw another line. Look at the lines. If the distance between the two lines is consistent to your eye -- it's straight enough for woodworking.

That's better! That first vid was sooo slooow!
If, "........to your eye -- it's straight enough for woodworking." Fair enough. That's what I'd say about eyeballing directly without a straight edge.

 

[Trafalgar]

Looking for the consistent distance between lines -- not converging, diverging, or with gaps in the middle is the same thing you do to check a square, for square. The outside edge of a square, essentially a straightedge itself, gets worn over time by the marking knife (why your marking knife shouldn't be made of too hard a steel, but that nuance has been long lost to the idiots). Same theory at work when you check it vs. a longer straightedge.

 

[Jacob]

Looking for the consistent distance between lines -- not converging, diverging, or with gaps in the middle is the same thing you do to check a square, for square. The outside edge of a square, essentially a straightedge itself, gets worn over time by the marking knife (why your marking knife shouldn't be made of too hard a steel, but that nuance has been long lost to the idiots). Same theory at work when you check it vs. a longer straightedge.

Well yes I get that but I've never felt the need for a long straight edge and am not sure why others do. Eyeball seems to be enough! I have planed long stuff by hand up to 14ft, but by eye. Can you get a 14ft straight edge?
I've used a chalk line quite often, for putting a mark on a long piece to be sawn, such as a slab from the timber yard.

 

[Trafalgar]

Well yes I get that but I've never felt the need for a long straight edge and am not sure why others do. Eyeball seems to be enough! I have planed long stuff by hand up to 14ft, but by eye. Can you get a 14ft straight edge?
I've used a chalk line quite often, for putting a mark on a long piece to be sawn, such as a slab from the timber yard.

A decent aluminum level is straight enough.

 

[Jacob]

A decent aluminum level is straight enough.

A hand planed length of board is good enough too. And adjustable!

 

[steve355]

Well yes I get that but I've never felt the need for a long straight edge and am not sure why others do. Eyeball seems to be enough! I have planed long stuff by hand up to 14ft, but by eye. Can you get a 14ft straight edge?
I've used a chalk line quite often, for putting a mark on a long piece to be sawn, such as a slab from the timber yard.

Here’s a proper 10ft straight edge. It needs to be lowered onto the workpiece with a crane.

So yes they do exist

10ft Straight Edge