## Re: [multimachine] Re: Math problem/How to Build progress/Thanks again Tyler/help

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• ... You are counting on a carpenter s square being square to within a few tenths (ten thousandths) of an inch - - - WOW - - highly doubtful (they are usually
Message 1 of 47 , Jun 8, 2011
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On Tue, Jun 7, 2011 at 3:53 PM, Pat <rigmatch@...> wrote:
> Would someone build one to test this out?
> If it works OK then it is possible to measure .001" with a carpenter's square and a plumb bob. I would do it myself but I can't walk far enough to make my way around a big box store to get the 1/8" aluminum rod.
> it's at "02 lathe ways level detector"
>

You are counting on a carpenter's square being square to within a few
tenths (ten thousandths) of an inch - - - WOW - - highly doubtful
(they are usually stamped out not precision cut!). Machinist's squares
are not even that accurate and a large machinist's square has a long
blade of 8 or 9 INCHES - - not 48 inches.

Accurate measurements require accurate tools. One can MAKE accurate
tools - - but that takes a lot of time to do - - so your trade off is
time or money. As one can get some not too bad tools (from China)
quite cheaply I prefer to spend a little money rather than a LOT of
time.

Darald
• Message 47 of 47 , Aug 21, 2011
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--- In multimachine@yahoogroups.com, "davi firdaus.drs" <hydrofilt.firdaus@...> wrote:
>
>
>
> --- In multimachine@yahoogroups.com, "David G. LeVine" <dlevine@> wrote:
> >
> > On 06/08/2011 03:17 PM, o1bigtenor wrote:
> > > Very different - - for sure!! You will still have a difficult time
> > > convincing me that a cobbled together tool made from a chunk of wood
> > > (most likely a softwood) clamped to a cheap steel or aluminum
> > > carpenter's square is going to give excellent repeatability. (Humidity
> > > changes alone will challenge that never mind temperature!)
> >
> > Since it is self calibrating, it is surprisingly good. Humidity WILL
> > matter, but is pretty constant over an hour. Temperature will matter,
> > but it is pretty constant at night.
> >
> > If the cheap square does not use wood, it will not be affected by
> > humidity, yes the cordage on the plumb bob will stretch and shrink, but
> > not all that fast and it will have a minimal effect on accuracy.
> >
> > Remember, we are not looking for perfect, just barely good enough.
> >
> > Dave 8{)
> >
>
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