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Mykee

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How accurate is accurate. I'm having a great deal of frustration getting rid of those tenths. I come from an engineering background where the tolerance was one or two tenths. Aaaaaaggghh.
Mike O.
 

SammyQ

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More info please. WHAT are you working on and tenths of WHICH unit of measurement? Oh, and wood moves. Allowing for "tenths" is part of the game...

Sam, who has different standards for wood vs metal...
 

Sawdust=manglitter

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It completely depends on what you're trying to make and what materials you're using. Generally speaking in woodwork you don't need metalwork/engineering levels of accuracy, but I know that can be difficult to shake if that's what you're used to. Even if you cut your wood to metalwork/engineering levels of accuracy it'll move with the seasons and completely throw out your accuracy.
 

thetyreman

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different types of woodworking require different tolerances, for example a garden gate vs a fine chest of drawers, timber framing, all different.
 

CHJ

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Mykee":35ih8k20 said:
How accurate is accurate. ....
When two mating components fit together, without undue clearance and are fit for purpose.
I find in working in wood the actual dimensions are in the main irrelevant, a storyboard, even if this is only the major component is far more conducive to getting an accurate fit than a rule.
 

woodbloke66

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CHJ":37kbjuot said:
Mykee":37kbjuot said:
How accurate is accurate. ....
When two mating components fit together, without undue clearance and are fit for purpose.
I find in working in wood the actual dimensions are in the main irrelevant, a storyboard, even if this is only the major component is far more conducive to getting an accurate fit than a rule.
Yep, that's pretty much it. I make a working drawing(s) (usually 1:1 or 1:5 with a cutting list) but they're only a guide and more often to see what the proportions of the piece actually look like. Components are cut to size but thereafter as Chas says, actual dimensions are irrelevant - Rob
 

AndyT

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I agree with Chas and Rob.

But to offer a simple example of how accurate "making to fit" can be: if you measure the difference between a tenon that fits properly into a mortise (hand pressure only, but won't fall out) and one that is too loose, it can be as little as a thousandth of an inch - a single, translucent shaving.
 
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AndyT":1j7ruo14 said:
I agree with Chas and Rob.

But to offer a simple example of how accurate "making to fit" can be: if you measure the difference between a tenon that fits properly into a mortise (hand pressure only, but won't fall out) and one that is too loose, it can be as little as a thousandth of an inch - a single, translucent shaving.
Fortunately we can re-create those shavings :p
 

woodbloke66

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AndyT":1rwgme4p said:
I agree with Chas and Rob.

But to offer a simple example of how accurate "making to fit" can be: if you measure the difference between a tenon that fits properly into a mortise (hand pressure only, but won't fall out) and one that is too loose, it can be as little as a thousandth of an inch - a single, translucent shaving.
You're absolutely right, but did you know that the domed end of a Japanese geno hammer is specifically designed to squish a tight joint to fit? The theory is that it's made a shade tight, then tapped both sides with the hammer to ease the fit. When it's glued the wood then swells and you've got a righty-tighty fit. I didn't realise until a few days ago when I saw a clip on UToob of a Japanese chippie doing exactly this process - Rob
 

AndyT

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That's new to me too. And it sounds much subtler than "bishoping" dovetails!
 

Fitzroy

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It’s definitely one of the issues that I find most challenging that I can’t rely on just measuring and cutting to a line. I’m slowly accepting that wood moves between each of my visits to a project and a large part of the skill of a woodworker is understanding how to deal with wood movement.

Fitz.
 

powertools

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If you are talking 10s of a mm you are there if you are talking 10s of an inch you have a way to go.
Is it flat straight and square will drive you insane if you let it.
 

Woody2Shoes

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woodbloke66":22uovg4v said:
AndyT":22uovg4v said:
I agree with Chas and Rob.

But to offer a simple example of how accurate "making to fit" can be: if you measure the difference between a tenon that fits properly into a mortise (hand pressure only, but won't fall out) and one that is too loose, it can be as little as a thousandth of an inch - a single, translucent shaving.
You're absolutely right, but did you know that the domed end of a Japanese geno hammer is specifically designed to squish a tight joint to fit? The theory is that it's made a shade tight, then tapped both sides with the hammer to ease the fit. When it's glued the wood then swells and you've got a righty-tighty fit. I didn't realise until a few days ago when I saw a clip on UToob of a Japanese chippie doing exactly this process - Rob
I first saw the technique used by this guy at the European Woodworking show a couple of years ago https://m.youtube.com/watch?v=bT5qLzbidRs Sadatsugu Watanabe
 

Trevanion

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I think it's all relative to whatever you're working on at any given time. With measurements, I tend to work to a half millimeter as the smallest unit but actual tolerances depend on the workpiece. If I'm 5mm or so too small on a door frame in the height for example, I'm not too fussed about it, although usually it is spot on what I intended it be 8). With the actual joinery of the mortice and tenons, I try to work until there is no perceptable gap on the shoulders rather than a defined tolerance. Of course, with machines set up for certain tasks, it's very straightforward to keep to a certain and repeatable tolerance compared with doing it completely with hand tools.

When I was in college the tolerance for a pass grade was at most a 3mm gap on a joint, distinction markings if there was less than a 1mm gap! :lol:
 

J-G

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Mykee":22pbe46t said:
How accurate is accurate. I'm having a great deal of frustration getting rid of those tenths. I come from an engineering background where the tolerance was one or two tenths. Aaaaaaggghh.
Mike O.
I also have an engineering background and have difficulty accepting that timber is not steel (or brass, alum etc) but I still aim for accuracy to 0.01mm. I get around most of the issues by using metalworking machinery (Mill and Lathe) helped by the fact that I tend to make 'small' items from well seasoned exotic hardwoods - I'm currently working on a presentation box for a set of pens - 180mm x 108mm x 38mm - some of the joints are 1.5mm wide and I have a 7mm hole in an 8mm thick side. The top is 4mm thick with 2mm square rebates so you can appreciate that working to ½mm is no good.

If I were using even the best well seasoned 'dry' softwood I could source, I wouldn't think of getting closer than 0.5mm

Incidentally, a tolerance of 'one or two tenths' ( I assume you mean tenths of a thou of an inch) is way outside what I had to work to --- there were times when I was calibrating inspection grade slip gauges to detail the deviation from 'size' in millionths of an inch.
 
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