Accuracy.

[D_W]

fellow who got me into woodworking is a (was, now retired) mechanical engineering manager. He found a couple of plans over the years that he wanted to build where the blow-ups had numerical errors (because he was recreating his own versions in autocad, complete with measurements to the thousandth). He's also the type (for anyone here who has written articles) who will find the contact information for the original author (who generally was just doing something for pay), notify them, and then ask for corrected measurements to check against his.

he can build angular items with great crispness. If he builds one splayed leg table, he has aluminum templates to assist with all of the angles- made once for that table, machined, and never used again.

People look at furniture, they don't measure it. When we put cabinets in a kitchen, they need to fit well together for their purpose. if they are a 32nd out of square but fitted together well, it's unlikely anyone will know.

I got into using hand tools because the torturous fitting and measuring of my mentor sent me looking for a solution where accuracy is fitted and to a purpose rather than a specification from autocad.

I've learned over time that when someone goes on and on about looking for more accurate ways to do things, and it's not a production environment, they don't need accuracy, they need experience.

 

[CHJ]

fellow who got me into woodworking is a (was, now retired) mechanical engineering manager. He found a couple of plans over the years that he wanted to build where the blow-ups had numerical errors (because he was recreating his own versions in autocad, complete with measurements to the thousandth). He's also the type (for anyone here who has written articles) who will find the contact information for the original author (who generally was just doing something for pay), notify them, and then ask for corrected measurements to check against his.

……..

Reminds me very much of the problems of modifying older generation aircraft built mainly by hand from paper drawn components. (Think Comet/Viscount/Canberra/'V' bomber era)
One particular project where the original aircraft manufacture was carrying out the conversion had employed some 300 new generation designers to work the project, all using CAD.

Manufacturer tried two times to fit a modified radio/navigation/autopilot console into the fuselage.

First build, made at manufacturing base would not go through fuselage door, too big. OOPs.

Second iteration of cnc produced components assembled inside the fuselage did not conform to the fuselage contours accurately enough to allow it to anchored in place.

Third iteration of components requested by us UNDRILLED, and assembled by our research installation fitters for them, fitted the fuselage perfectly.

Oh the joys of trying to transfer old designs to CAD or match CAD designed changes to older hand built aircraft.

 

[TheTiddles]

Accuracy is of little use in woodwork, precision is usually what you want. If you plan your process well, use a single fence setting for every operation that needs it etc... It gets a lot easier to be precise.

Aidan

 

[Trainee neophyte]

Having gone completely metric (I live in a metric country), I recently discovered that 16ths of an inch are much easier to see than millimetres! I am at that age where it suddenly isn't quite as easy to see marks as it used to be, and working in inches is so much easier!

This is probably the wrong attitude to bring to this thread...

 

[ScaredyCat]

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.

I'm continuously going through this.

.

 

[Suffolkboy]

.....When I was in college the tolerance for a pass grade was at most a 3mm gap on a joint.......

Blimey! A well motivated beaver could manage that.

I met a few well motivated beavers during my college days.

 

[Phil Pascoe]

You met some of Kurt Vonnegut's "wide open beavers"? :lol:

 

[toolsntat]

After years of training myself to get to 1/10thmm and cockon square with wooden inspection tooling, it's taking even longer to adjust to if it looks right it is right.
Still square and fit obsessed though :roll:
Cheers Andy

 

[TheTiddles]

I’ll let you into a secret, if you use imperial... you’re still using metric, an inch is defined as a number of millimetres

 

[MusicMan]

Yup, 25.4 mm exactly.

 

[Cheshirechappie]

I’ll let you into a secret, if you use imperial... you’re still using metric, an inch is defined as a number of millimetres

T'was not always so. There was a time when an inch was the length of three barleycorns laid end to end, or one twelfth the length of a man's foot.

That was long before some pillock invented the metre, or before the standard metre was defined as equal to 1650763.73 wavelengths of the orange-red emission line in the electromagnetic spectrum of the krypton-86 atom in a vacuum (assuming you happen to have an interferometer handy).

Frankly, in the privacy of your own workshop, the length of your foot is a rather more practical measure. Just don't confuse it with anybody else's foot, and you'll be fine. Also, the practical application of a pair of dividers will give you inches, or pretty much any woodworkingly-useful sub-division thereof you wish for.

 

[Jacob]

.....Also, the practical application of a pair of dividers will give you inches, or pretty much any woodworkingly-useful sub-division thereof you wish for.

Yep. Took me some time to work out why they were called dividers i.e. used for division :roll: and the origin of the duodecimal system. Mark out your own foot length. Divide by 2,3,4 , and you have 6", 4", 3", 2", 1". Extrapolate to give you 12 inch divisions. Duodecimal system too complex for dividing the inch so just go in halves down to 1/64" about the limit of what is visible.
If you actually want to use dividers for your precision making it's handy to have several sizes.
Decimal system was for counting rather than measuring; accountants use their fingers for 10 and toes for 20 which has a name in some countries, here as the "score".

 

[Woody2Shoes]

.....When I was in college the tolerance for a pass grade was at most a 3mm gap on a joint.......

Blimey! A well motivated beaver could manage that.

I met a few well motivated beavers during my college days.

Were the mating surfaces within tolerance ?

 

[Woody2Shoes]

One of the great advantages of working in imperial is how divisible everything is. Doing other calculations in imperial is less easy - what's 23% of 6"3/8 ? :?: Working in a mixture of metric and imperial is a good way to cause serious brainache/trouble....

 

[Mykee]

Thanks for all your replies. I always work in millimetres. I guess the skill is in knowing how to deal with any discrepancies.
Mike O.

 

[Trainee neophyte]

.....Also, the practical application of a pair of dividers will give you inches, or pretty much any woodworkingly-useful sub-division thereof you wish for.

Yep. Took me some time to work out why they were called dividers i.e. used for division :roll: and the origin of the duodecimal system. Mark out your own foot length. Divide by 2,3,4 , and you have 6", 4", 3", 2", 1". Extrapolate to give you 12 inch divisions. Duodecimal system too complex for dividing the inch so just go in halves down to 1/64" about the limit of what is visible.
If you actually want to use dividers for your precision making it's handy to have several sizes.
Decimal system was for counting rather than measuring; accountants use their fingers for 10 and toes for 20 which has a name in some countries, here as the "score".

Try counting the joints of your fingers, using your thumb as a pointer. Each finger has three, which means you can count up to twelve on one hand. Use the other hand to count how many twelves, and you are up to 144! Also know as... a gross.

What I ponder about is when and how we lost the art of counting to 12 on fingers - it is a cultural thing, you would think.

 

[Cheshirechappie]

I don't think it really matters whether you work in inches, millimetres or cubits; provided you're comfortable with what you're doing. If it works for you....

The 'absolute measurement' thing is something I sympathise with, being of an engineering background myself. Making one-offs from wood in the home workshop can be a completely different mindset, but not an easy one to adopt if your training and experience is all about absolute measurements and specified tolerances.

Something that might help is to make a couple of small projects using no measuring tools whatever. A couple of things spring to mind - a wooden spoon, made from a scrap of hardwood, whittled by hand and eye, or maybe the shape just drawn on the wood freehand until it looks 'about right'. Another is a small wooden tray with dovetailed joints - plane up a length of wood, set the gauge to the thinnest part and plane to that thickness, ditto to width, cut two sides of equal length, two ends ditto (not measured, just eyeballed), set out the joints 'by eye', cut and fit joints, lay tray on scrap of plywood to mark size, pin on, trim up with a plane.

That might help to break the mental block, or at least alert the mind to 'other ways of thinking'.

 

[Woody2Shoes]

I don't know if it's too late to add this book (or one of the other two by the same people) to your Xmas list:

https://lostartpress.com/collections/bo ... h-to-tools

 

[D_W]

One of the great advantages of working in imperial is how divisible everything is. Doing other calculations in imperial is less easy - what's 23% of 6"3/8 ? :?: Working in a mixture of metric and imperial is a good way to cause serious brainache/trouble....

Decimal inches is how people do things here if they're going to work like that.

Actually, I learned that from an Englishman - same one I mentioned before - he likes to use autocad for all of his plans and if you're going to try to be accurate to the thousandth, just state the measurements that way.

 

[Woody2Shoes]

One of the great advantages of working in imperial is how divisible everything is. Doing other calculations in imperial is less easy - what's 23% of 6"3/8 ? :?: Working in a mixture of metric and imperial is a good way to cause serious brainache/trouble....

Decimal inches is how people do things here if they're going to work like that.

Actually, I learned that from an Englishman - same one I mentioned before - he likes to use autocad for all of his plans and if you're going to try to be accurate to the thousandth, just state the measurements that way.

I'd rather work in metric in that situation to be honest! (I am old enough to naturally "think in" imperial and have to remember to 'translate' for younger people). My hundred year-old house was built in imperial and I've done quite a lot of work on it - initially using metric, but I soon realised that I would stay sane - and the proportions would work much better - working in imperial.

Cheers, W2S