Expect Too Much of Tools Too Little of Self?


The question:
Do we expect too much of our machines and not enough of ourselves
An earlier thread on combination machines like the Robland X31, Mini-Max and Felder, got into the advantages of dedicated, stand alone machines over combination machines (table saw with rip fence, joiner with fence and planer). One major difference was that with combination machines, you lose your last set up for each operation and don't with dedicated, stand alone machines. Another noted difference were the rip fences. U.S. market fences typically go all the way to the back of the saw table and often are secured front and back, while combi fences typically only lock down in the front and some only extend just beyond the back of the saw blade.
But the difference that led to this post was the difference in setting the rip fence. With a combi you typically use a tape, or piece of wood the width you want, to set the fence. With a US market rip fence you just set the cursor to the deisred width on the fence's measuring tape.
With the latter, the assumption are: a) that the tape for the fence is accurate to the precision it implies by its smallest gradation - 1/32nd or even 1/64ths b) that the implied accuracy noted in "a" is good for most of, if not the entire length of, the tape c) that when you lock the fence down it won't move - at all. d) the tape only need to be set to the saw blade once and will be accurate forever after (amen)
We expect these assumptions to be true - even though, if you think about it - they're not. "a", "b" and "c" have some slop. And if you change blades to best suit the material you're working with, or have tilted the blade for a bevel cut and then broght it back to it's vertical "stop" then "d" may not be true either.
Do you keep a good try square or starrett four inch double square in your shop aproan and check for square on stock you're prepping? Do you keep a good caliper in your shop apron to check the thickness of the stock you're planing? Or do you just expect the machine you're using to be as accurate as you think it is?
charlie b (now I'm going out to the shop to route some mortises using my Micro Fence which lets me dial in - in thousandths! I've got a mini/midi lathe bench to build. Another "quick and dirty" that'll likely get away from me and end up with inlaid legs and maybe some nice beading. Now if I can just remember where I put all that ebony - maccassar of course)
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charlie b wrote:

[shnibble]
I don't have any nice equipment like that, so I guess I'm totally dependent on me.
I do find myself checking everything three times, though. And because I'm inexperienced, I'm also reviewing whether I'm following all the layout rules... measuring from the reference edge, etc.
I'm also accumulating a lot of tools to facilitate that, as well: I wasn't satisfied that my cheapol protractor was accurate, so I got a cheapol dial protractor, and tested them against eachother, and my work against them to find they are all identically (in)accurate. I also have engineers squares, and am jonesing for an engineer's level. I threw up my hands when I couldn't get agreement between two rulers (er, one bought on a weekend in Mexico), a tape, and a pad of graph paper: one of those "all imperial" rulers resolved that with sufficient agreement with the paper.
I put together some marking tools that I can live with.
In fact, so far I'm not making much outside of (good enough) tools, and buying more! It's all good, I think.
er
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On Wed, 15 Feb 2006 09:55:44 -0800, charlie b wrote:

For a number of years I earned my living as first a machinist and then a tool & die maker.
As far as I am concerned, a scale (tape ... rule) on a machine is no more than a starting point. Ditto for a dial and so on.
Bill
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Except for the fence on a table saw if we're talking Beismeyer, Unifence, (1/64th accuracy) or other top-end fence systems or the digital read-out on the Powermatic 15" planer if set up properly.

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On Fri, 17 Feb 2006 06:37:44 +0000, Max Mahanke wrote:

Sorry, but being accurate to within 1/64" just isn't all that impressive. Less than an hour ago I re-sawed a piece of 3/4" x 3" x 41" tamarind on my Craftsman TS with the original fence and a sacrifical piece of mdf subfence, and held ~.009" parrallelism. That's mighty close to     1/128".
It only took a couple minutes to set up for the cut, not much longer than a top-end fence system would. The funny thing is that I really didn't need that much accuracy for this cut. It's going to be part of a glue-up for a cane that will be ripped and re-glued a couple more times before ending up on the lathe. However, since I did an extremely good job tuning the saw when I first started using it last year, that level of accuracy simply comes automatically.(*)
Even if I had a DRO on every piece of equipment in the shop I'd still take a measurement with another, known good, tool before making a final pass on a critical part. In this case, I used a .325" jo-block stack to set the distance between the fence and the blade and then measured the sawn pieces with dial calipers (decimal inch). I really only got one shot at this cut.
Except for making endless test cuts, it's the only 'gotcha' insurance I know of.
Sometimes a 64th is 'close enough', other times it's not. But if you don't take a measurement with another tool, how can you be certain that you held even that tolerance?
Is that why we woodworkers need to know so much about sandpaper and scrapers?
Bill
(*) I can't be certain that there is any error at all in the relationship between the saw arbor and the miter slots / fence face. My dial indictaor showed about .002" error but there could have been other causes of this error such as inconsistent pressure being applied to the indicator base, poor finish / uneven wear patterns on the inside of the miter channel and so on.
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Wed, Feb 15, 2006, 9:55am (EST-3) snipped-for-privacy@accesscom.com (charlieb) doth wonder: The question: Do we expect too much of our machines and not enough of ourselves <snip>
Check my thread on, Full List Of Tools For Boatbuilding.
JOAT IThere is no vaccine against stupidity!
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