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wcndave

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There have been a few recent threads about how close to final size one should get to before planing and thicknessing.

Although it seems tempting to mill an entire board to final thickness and then cut out your parts, you need to get close to final size, but leaving enough for snipe.

I need some 3/4" square birch, and have a huge 8' x 2.5" x 14" board.

So I cut a piece 2" x 7/8, planed to final thickness and then just ripped down the middle.

You can see in the picture that even with this small piece, the forces released on ripping were huge.

uploadfromtaptalk1345532875621.jpg


I had put the planer away by then so decided to hand plane them as was getting late.

I had a lot of bad tear out, so decided to use the back bevelled blade Matthew did for me a while back. What a difference! Like planing wax, in both directions...

That was the heaven part :)
 

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devonwoody

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Are you saying that the board was 14" wide and 2.5" thick?

8ft. long as well, I think it would have to be an exceptional good piece of timber to get those battens you needed!
 

wcndave

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devonwoody":25ukepp4 said:
Are you saying that the board was 14" wide and 2.5" thick?

8ft. long as well, I think it would have to be an exceptional good piece of timber to get those battens you needed!
Why would that be the case? Where else would battens come from?

I took this piece to very close to final size, however the final cut released a huge curve. (turned the picture the right way up now)
 

Jacob

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wcndave":1c7ip18y said:
..
Although it seems tempting to mill an entire board to final thickness and then cut out your parts, you need to get close to final size, but leaving enough for snipe.....
You need to rip to width and saw to length before you go anywhere near a plane. Ripping after planing is doomed to fail.
To get 3/4" square finished planed you need to start with 1" square sawn minimum for short lengths or bigger for long lengths.
 

wcndave

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Jeez, thanks Jacob for pointing out what was the actual point of my post!!

People often say "i need 10 pieces 12" by 4" so I'll plane/thickness one board 5' x 8" so that the p/t process is easier...". This does not always work, and can end up being very off indeed.

I was demonstrating how much force is released even with a small piece.

I must admit to thinking that with such a small piece all the forces might have been released and i would get away with it, however this piece was oversize so I could plane it down further.

i was simply amazed at the extent of the bend.
 

custard

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wcndave said:
Although it seems tempting to mill an entire board to final thickness and then cut out your parts, you need to get close to final size, but leaving enough for snipe.
quote]

If you're experiencing material degrees of snipe on a regular basis, then I'd suggest re-looking at technique and machine settings, rather than just accepting and allowing for it.
 

Stormer1940

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Sawing then planing as Jacob Has pointed out. The only time I face and edge on the p/t before sawing is if I need to make beading.
 

wcndave

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ok, seems ppl did not get this.

a lot of people have posted about making a nice board, then cutting your parts out of it, and others have pointed out this is not a good idea.

this is a picture demonstration of that fact.

I will add however that i do plane prior to sawing simply to give me a flat surface to run on my TS and against the fence, however it is not intended as a dimensional plane.
 

Jacob

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wcndave":24j48qer said:
.....
I will add however that i do plane prior to sawing simply to give me a flat surface to run on my TS and against the fence, however it is not intended as a dimensional plane.
I think ppl are saying don't do that either!

Cut to length first if poss. Then rip to width - If it's too wavy so sit against a fence then cut freehand to a chalk line.
 

Togalosh

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Jacob":temamxbv said:
wcndave":temamxbv said:
..
Although it seems tempting to mill an entire board to final thickness and then cut out your parts, you need to get close to final size, but leaving enough for snipe.....
You need to rip to width and saw to length before you go anywhere near a plane. Ripping after planing is doomed to fail.
To get 3/4" square finished planed you need to start with 1" square sawn minimum for short lengths or bigger for long lengths.
eu(bloody)reka !

..none of the books I've read so far have said anything about this. Can you please explain what's going on to cause this & are there any more similar proceedures to do with milling stock?

Thanks wncdave for bringing this up.
 

wcndave

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Basically there are forces and stresses within wood that cause it to deform when you release those stresses. In my early days I would mill perfect planks of wood to then cut all my parts from. However your should cut all if your parts to some oversize and plane/thickness as the last step.
If I need a 1x2 I will cut 1.5x2.5 and them slowly mill it down, bring aware as I do so that the flat sides may not stay flat as I do so

The amount of oversize is based on how stable your wood is, eg cutting a kiln dried piece will cause less deformation than a big waney edge piece as it has had time to stabilize.
 

Jacob

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wcndave":xy6ifsgg said:
......
If I need a 1x2 I will cut 1.5x2.5 and them slowly mill it down, bring aware as I do so that the flat sides may not stay flat as I do so
But cut to length first - unless you want very short lengths in which case you could combine them into one sensible length.
 

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