Is it just me???

To re-quote: "Originally Posted by Travis Johnson
As a machinist I feel compelled to tell you that the eye can start seeing discrepancies in the .012 to .015 range without a straight edge or anything."

I have to agree, the eye can often see small discrepancies that might slip by using measuring devices.
On a chair I built recently, after finishing I noticed that a rear spreader looked wrong. On examination, I determined that one side was wider than the other. I probably wiggled it slightly running through the table saw. But, when I put a tape measure on the piece, I cannot discern any measurable difference. It is less than the thickness of the black line on the tape. The piece is doweled on and I'm not about to remove and repair. I'll just fall back on the time tested axiom, "A man running for his life would never notice it."

Frank, if you're talking that small of a discrepancy over the width of a chair back, have you considered an optical illusion? A variation in grain can often fool the eye and make things look odd. I recently made a door and the rail on one side looked much wider than the other. Both were cut at the same time with the same saw setup so I knew they were identical. The culprit, one rail Had straight grain, the other sort of a cathedral grain running off the side. Like you I didn't notice it until after I finished it and had it sitting in the house. It bugged me every time I looked at it and in the end I made a new door and now it looks fine.

Mike
 
I'm a architect and I'm lucky if they can set a foundation out on site within +-2". As I'm getting older I'm finding my eyes can't focus on anything under 1/16 on a scale which is ok as I prefer metric, +-.5 mm is ok with me :)

I'm a builder, and if my mason couldn't "set a foundation" on a site within +/- 2", I'd be out looking for another. We typically have our foundations square to within 1/4".
 
To re-quote: "Originally Posted by Travis Johnson
As a machinist I feel compelled to tell you that the eye can start seeing discrepancies in the .012 to .015 range without a straight edge or anything."

I have to agree, the eye can often see small discrepancies that might slip by using measuring devices.
On a chair I built recently, after finishing I noticed that a rear spreader looked wrong. On examination, I determined that one side was wider than the other. I probably wiggled it slightly running through the table saw. But, when I put a tape measure on the piece, I cannot discern any measurable difference. It is less than the thickness of the black line on the tape. The piece is doweled on and I'm not about to remove and repair. I'll just fall back on the time tested axiom, "A man running for his life would never notice it."

Welcome to my world my friend. In custom yacht making, with the stakes this high and the prices into several millions of dollars, blueprints are merely guides, the eye is everything. This sounds crazy but its true, if you measure something a dozen times and the measurement stays the same, and yet it still "looks off", the looks win every time. Plain and simple, it just has to look right and yeah this kind of thing can drive you crazy. What I have found is that by being as precise as possible, as early into the stages of the job as possible, you keep the "look" right, and keep the measurements right as well.

Still every part we make on a boat we make a 3 times. Welcome to custom yacht building. Its not for everyone.
 
Gentlemen,

Back to the original subject, trying to talk about setups and measurements to the thousandths. It's easy to mock this kind of thing, but to do that you have to ignore the real point. We'll call it the "Doofus Factor."

I'm the perfect example. You all know by now what a complete doofus I am. I started with building garden structures with a skill saw. I was lucky if I even got close to a mismarked line holding a 2x4 in one hand and the skil saw in the other. Then I got a direct drive benchtop, and got closer. It cost me $40, remaindered, with parts missing, at the despot. Durned near killed myself with that thing, too. When we moved into this house, I splurged, shockingly and incredibly: I bought a ridgid contractor saw. I spent a fortune on that thing, like, $450. I got a lot closer, but I was building different stuff, and it looked as wrong as the garden structures did... only now, I couldn't plant vines to cover how out of square things were. The naked truth I had to face was that I was a complete doofus.

But wait! Maybe not. Maybe there's hope for me! MAYBE ITS THE TOOLS! Yeah, that's the ticket! Ever spent an entire day trying to get a contractor saw arbor and blade close to true to a miter gauge slot? I have... and only got it to within 10/1000. Whoops, one one hundreth. At least I wasn't burning every piece of maple anymore. Or even every piece of sycamore. But things still weren't coming out right... And you should have seen how badly things were going on the router table. So I did the unthinkable, driven to desparation by Doorlink's mockery: I spent almost as much on a decent fence as I had on the tablesaw. I thought my suffering had ended...

Got it all set up. Took a board, set the fence to 2", and cut. Whoops, better adjust, try again. Whoops... on and on like that, most of the afternoon. I thought I might be able to get a board that measured 2" in width, all the way along its length. But alas!

As I type, I'm sitting in the kitchen. The laptop's sitting on the big central island I made, the one Doorlink always wanted. Less than six inches from my left wrist is the place where a router misalingment ate into the formica, cutting through the blue surface material and revealing the dark backing underneath. It's the first thing you see when you walk into the kitchen. To my left is a large picture frame with a visible gap in the top left. To my right, a large refrigerator cabinet, with a face frame, one component of which is perfect in three corners, and visibly off in the fourth.

Given all that, I would be THRILLED if I got anything close to even 5 1/1000s. I would crow about it, and reveal myself as the doofus everyone knows I am! It was only after spending an entire day on each major tool, trying to get each one as dialed in as I could, that I realized the problem wasn't cast iron implements, or steel straight edges, but pure and simple karma. In a previous life, I must have carelessly mocked some poor rushed underpaid woodworker's joinery, and now the universe is giving me my just desserts! I think the only solution is to hang up as many images of the goddess in my shop that I can, and pray to her often, not for better setups, but for forgiveness! How long, o lord, how long must I do penance for that unremembered careless joke sometime in the distant past? Sadly, no answer is forthcoming... ;)

Thanks,

Bill
 
I'm a builder, and if my mason couldn't "set a foundation" on a site within +/- 2", I'd be out looking for another. We typically have our foundations square to within 1/4".

For everyday professional work thats the way to go... for a once off house, like mine, its easy enough to correct a lot of problems in the foundation. We're probably out about 3/4" (by which I mean +/- 3/8") in the one spot where it was noticable in later construction. Two inches is about the upper limit of what I'd be comfortable with fixing, though I've seen worse.
 
In a previous life, I must have carelessly mocked some poor rushed underpaid woodworker's joinery, and now the universe is giving me my just desserts! I think the only solution is to hang up as many images of the goddess in my shop that I can, and pray to her often, not for better setups, but for forgiveness! How long, o lord, how long must I do penance for that unremembered careless joke sometime in the distant past? Sadly, no answer is forthcoming... ;)

You're too funny Bill:) Now that you mention it, I've got a sinking feeling that might be my issue too... prayer hasn't worked yet, let me know if you find the secret though:rolleyes:

While I think we all strive for the perfection, the reality is in WW that nothing is ever perfect. On every major piece I've made I can pick out minor flaws, I suspect even the great masters can too. The true sign of a craftsman is the ability to work on the fly and make his mistakes or just plain oops moments work or cover them. It's the nature of the medium.

Mike
 
Frank, if you're talking that small of a discrepancy over the width of a chair back, have you considered an optical illusion? A variation in grain can often fool the eye and make things look odd. I recently made a door and the rail on one side looked much wider than the other. Both were cut at the same time with the same saw setup so I knew they were identical. The culprit, one rail Had straight grain, the other sort of a cathedral grain running off the side. Like you I didn't notice it until after I finished it and had it sitting in the house. It bugged me every time I looked at it and in the end I made a new door and now it looks fine.

Mike

Not optical. Definitely wider on the right side than left.
 
I just read a post on another forum from a guy complaining the fence on his jointer was out .00015". Yes, we're talking 15 TEN THOUSANDS of an INCH!

It is awfully easy to accidentally either type the wrong number, or misinterpret it, as shown by the quote. I point out the error only to show that someone who obviously understands can make a mistake.

People post to ask questions, and many times the answer is that those tolerances are not appropriate to the problem at hand -- though they may well be in another context. It can also be difficult to say that without appearing to attack, particularly when many people pile on -- I am thinking of a forum less civil than this one. But that is the answer they need to get.

The distinction between machine setup tolerances and wood tolerances is significant. But so is the distinction between helpful responses and unhelpful ones. I've seen cases where people have asked reasonable questions about whether a certain level of error is significant, and been ridiculed for asking something they didn't ask, more zeros appearing with each misquote (again, not here).
 
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