On Sep 17, 1:27=A0am, Tom Veatch wrote:
> Interesting.
>
> Just for comparison, the standard (implied) tolerances on engineering
> drawings at the aerospace firms I was associated with throughout my
> career was X.XX +/- .03, and X.XXX +/- .010. Any tolerances other than
> those, looser or tighter, had to be explicitly specified in the
> dimension callout. Often those non-standard tolerances, and virtually
> all 4 place dimensions, had to be justified to the group leader or
> project engineer and, unless the need was obvious, would frequently be
> questioned by the manufacturing engineers or planners.
>
> Tom Veatch
> Wichita, KS
> USA
Hi Tom,
Different industries, different customers, different vendors,
different tolerances. In some areas a particular company dominates
the market and their standards tend to prevail. For example, here in
Boise it's Micron. Just about every machine shop in town does
something for Micron. I'm sure in Seattle it's Boeing. I'd bet that
Detroit is dominated by automotive needs. And, some companies have a
formal review process (sounds like your experience) while others let
engineers run open loop. It's always uncomfortable questioning
tolerances from one of these open loop guys. I've met a few who have
never built anything in their entire life.
Ed Bennett
[email protected]
On Sep 15, 7:02=A0am, spaco <[email protected]> wrote:
> Why don't they give tolerances on wooodworking projects and plans like
> they do for metalworking? =A0 Are there some tolerances that are so
> "standard" that everyone but me automatically knows them?
They really SHOULD give similar tolerances. Weekend
woodworkers (who cut the wood in week 1 and fit it
together in week 3) can't easily hold tight fits due
to the wood movement between operations. That would
make the (printed) tolerances useless (in week 1, you
cut it, and it's within specs; in week 3, a perfectly
cut tenon doesn't fit because the mortise shrunk).
I've also cut dozens of oak sticks, then (actually
planning this time) gave them a half month to relax
before hand-planing to make 'em straight again.
There are some joints (sliding dovetail) I have gaged carefully
with feeler gages, then readjusted a jig to make 'em tight.
That time, the slot was the exact same size as the
tongue, +/-.002" tolerance (it took linseed oil and mallets
to assemble). If I was using water-based glue (white glue,
or yellow) I'd open the gap to about .010" and glue with
confidence.
When I made my doweling jig, I measured from a dowel
in the first drillguide hole to a dowel in the drill press chuck,
and tweaked the hole/hole spacing to +/- .001". The jig
is in hard (filled) plastic with steel bushings, so that's not
exactly a woodworking tolerance...
Another tight-tolerance situation is cutting and fitting
plugs; a plug-cutter and boring bit have to match
(hole +.002" to .006" oversize) or the plug doesn't look right
when finished. That, or the plug doesn't fit in.
It is said that old turned chairs were made
with dry wood crossmembers fitted to green uprights,
and the uprights shrank to make a tight joint, even
with no glue. My sister has some such chairs, probably
about 200 years old, and still strong. The tolerance
for such fitting, assuming .005" compression of the
crossmembers in a 0.600" hole, tangential to grain,
is about .030" (six percent shrinkage when drying),
so old craftsmen were definitely doing better than 1/32
inch tolerance to get that kind of joint to work.
On Tue, 16 Sep 2008 12:58:05 GMT, Woodie <[email protected]> wrote:
>mac davis wrote:
>> Most important, IMHO, is learning to tolerate neighbors borrowing tools.. lol
>
>My ex left her 'just for women' toolkit. When neighbors ask to borrow
>tools, I just hand them the nicely organized pastel case full of poorly
>made tools.
>They seldom ask twice.
Damn... why didn't I think of that!
My wife has one of those that someone gave her, and since she uses real tools,
she's never opened the pretty pink case..
mac
Please remove splinters before emailing
"Leonard Shapiro" <[email protected]> wrote in message
> 1/6 of and inch is about as small as it gets in woodworking due to wood
> movement
I certainly don't agree with that. There's been many projects I've built
where 1/16" is simply too great a length to properly assemble my project.
When necessary, (not always such as my recent picnic table), I've calibrated
and cut my parts on the tablesaw to 1/64" of an inch.
dpb wrote:
> Wonder how much different it is two hours later, what more the next
> morning???
If you start out with multiple boards of the same moisture content, then
they're all pretty close to the same thickness the next morning,
regardless of the actual dimensions. That's usually all that matters.
An accurate digital readout on the planer is really nice if you need to
go back and make a new board to replace one that you've wrecked.
Measure the other boards, find another board with the same moisture
content, and plane the new one to the thickness of the others.
Chris
"spaco" <[email protected]> wrote in message
news:[email protected]...
> Why don't they give tolerances on wooodworking projects and plans like
> they do for metalworking? Are there some tolerances that are so
> "standard" that everyone but me automatically knows them?
>
> Pete Stanaitis
Just my Opinion, and nothing more!
Tolerances are something from interchangeable parts, production lines, and
factory production. If your wood part drawing is for / from a manufacturing
or assembly line plant, you can be sure there should be tolerances and QC
inspections notations.
If you are a hobbyist then most of your work is going to be one of a kind
type of project making. You apply your own tolerances to be with in the
limits of YOUR measurement equipment and skill level.
There are two separate tolerances you need to be aware of:
As a hobby woodworker, the most common measurement device is most likely the
yo-yo measurement tape. Please don't get this group started on the errors
induced by the printing of the marks on metal backing on your measuring
tape. I still think the best is a story stick for a project, where all
measurements needed are recorded (marked) on a single stick at one time, by
one person.
The second error is in your transferring the mark(s) from the ruler (or
story stick) to the work piece. This should be very small, about one half
of the smallest marking on the ruler used. For example a ruler with 1/16"
markings, tolerances should be +/- 1/32", like wise a steel machinist ruler
with 1/64 engraved markings, we at the wreck will expect you to be +/-
1/128"
As another posted, way before interchangeable parts and the Auto Industry,
one would make the cuts a small amount fat, and then use hand tools to sneak
up on it from both sides fitting together.
On Mon, 15 Sep 2008 09:02:02 -0500, spaco <[email protected]> wrote:
>Why don't they give tolerances on wooodworking projects and plans like
>they do for metalworking? Are there some tolerances that are so
>"standard" that everyone but me automatically knows them?
>
>Pete Stanaitis
Most important, IMHO, is learning to tolerate neighbors borrowing tools.. lol
Other than that, "If it fits and looks ok" works well for me..
mac
Please remove splinters before emailing
On Sep 15, 10:02 am, spaco <[email protected]> wrote:
> Why don't they give tolerances on wooodworking projects and plans like
> they do for metalworking? Are there some tolerances that are so
> "standard" that everyone but me automatically knows them?
Woodworkers don't generally work with tolerances like that, and would
be surprised at what sort of tolerances they are actually achieving -
they just don't get there the same way. If it's critical then it's
much more likely going to be done by cutting it long and sneaking up
on it or test cuts in scrap than with careful setup of the machines.
Probably because the materials are a lot cheaper and easier to
machine.
I make every cut as accurately as I can, but I don't cut all the parts
ahead of time and then expect it all to just fit together. It doesn't
really matter how accurately the space the drawer fits into matches
what the plan says if you haven't made the drawer yet and you mark it
from the actual opening.
spaco wrote:
> Why don't they give tolerances on wooodworking projects and plans like
> they do for metalworking? Are there some tolerances that are so
> "standard" that everyone but me automatically knows them?
Tolerances in wood depend on wood type, grain, moisture content, and
even how the particular part is used...
I'm still kidded by people in one of the CNC forums for my 1-hour,
2-hour, and same-day joint designs because if the joint wasn't assembled
within a particular timeframe, it could probably /never/ be assembled.
My brag was that I didn't need the glue to hold the parts together, but
to lubricate the assembly. :-)
(And I did build my own CNC joinery machine to improve the accuracy of
the cutting - photos at the link below.)
--
Morris Dovey
DeSoto Solar
DeSoto, Iowa USA
http://www.iedu.com/DeSoto/Projects/JBot/
On Mon, 15 Sep 2008 09:02:02 -0500, spaco wrote:
> Why don't they give tolerances on wooodworking projects and plans like
> they do for metalworking? Are there some tolerances that are so
> "standard" that everyone but me automatically knows them?
>
> Pete Stanaitis
Leaving the "my tolerances are smaller than yours" brigade to carry
on measuring each other! in practice, the tolerances are about the
width of a pencil line. You can sharpen (or not) your point if you
really need better than 1/2 mm or so.
Most people just tighten the clamps a bit more if the tolerances
don't work in their favour.
Just my 2p worth.
On Sep 15, 10:58=A0am, "Leonard Shapiro" <[email protected]>
wrote:
> 1/6 of and inch is about as small as it gets in woodworking due to wood
> movement
>
> Len
> "
I disagree Leonard. I constantly keep things down to 1/32 or 1/64.
Angularly, I certainly maintain =B1 0-degrees on angular measurements..
at least I try.
On Sep 15, 6:20=A0pm, "dadiOH" <[email protected]> wrote:
> spaco wrote:
> > Why don't they give tolerances on wooodworking projects and plans like
> > they do for metalworking? =A0 Are there some tolerances that are so
> > "standard" that everyone but me automatically knows them?
>
> > Pete Stanaitis
>
> As others have said, tolerances aren't that important. =A0What *is* impor=
tant
> is that the various pieces that define a given dimension in the finished
> piece be identical in that dimension.
>
> --
>
> dadiOH
> ____________________________
>
> dadiOH's dandies v3.06...
> ...a help file of info about MP3s, recording from
> LP/cassette and tips & tricks on this and that.
> Get it athttp://mysite.verizon.net/xico
Eggggzacktly. Piece A goes into Hole B, there should be minimal error.
But, as Ed said, who gives a rat's ass if the over-all project is out
by as much as a quarter inch. As Angela's dad used to say...and I
never had the pleasure to meet that man (A WW2 Vet), "A man sometimes
has to chose the hill he's gonna die on."
If you're making a bench out of twigs, nobody cares (or knows) if
you're out an inch. But....now mount a Soss hinge....
spaco <[email protected]> writes:
> Why don't they give tolerances on wooodworking projects and plans like
> they do for metalworking? Are there some tolerances that are so
> "standard" that everyone but me automatically knows them?
Wood breathes, and expands and contracts with changes in moisture.
Precision depends upon the amount of compensation needed to adjust to
these changes, whcih depends on the size and length of each piece of
wood involved. And how well the joint will hold, and the quality of
construction.
Doll house miniatures versus timber framing has completely different
requirements for precision/accuracy.
Thanks to all who replied. I get the picture.
I reverse engineer (metal)components for a no longer-produced
all terrain vehicle for my son. I have to create drawings for myself
when I make the parts and for others when he farms things out (higher
volume than I want to deal with). Particularly for the outside stuff, I
am the only guy alive (probably) who knows what fits with what, so I
have to figure and apply tolerances as needed.
The game I play with myself is to make the drawings good enough that
the vendors are happy, my son's costs are minimized and the parts NEVER
fail to fit and function.
Pete Stanaitis
------------------------
spaco wrote:
> Why don't they give tolerances on wooodworking projects and plans like
> they do for metalworking? Are there some tolerances that are so
> "standard" that everyone but me automatically knows them?
>
> Pete Stanaitis
spaco wrote:
> Why don't they give tolerances on wooodworking projects and plans like
> they do for metalworking? Are there some tolerances that are so
> "standard" that everyone but me automatically knows them?
>
> Pete Stanaitis
As others have said, tolerances aren't that important. What *is* important
is that the various pieces that define a given dimension in the finished
piece be identical in that dimension.
--
dadiOH
____________________________
dadiOH's dandies v3.06...
...a help file of info about MP3s, recording from
LP/cassette and tips & tricks on this and that.
Get it at http://mysite.verizon.net/xico
"Edwin Pawlowski" wrote:
>
> If your factory is making bearings to fit crankshafts made by a
> different factory, different story. Oh, those pistons better fit
> the block too.
The advent of close tolerance manufacturing revolutionized, among
other thing, the manufacture of rifles/arms as well as ammunition for
them.
Made life lot easier for the army.
Way back when, a FoMoCo engine plant was one of my customers.
Worked on a project that involved measuring both pistons and block
bores, correlating the data, then selecting specific pistons in
specific bores based on that data.
Since it had to be done at high speed, it was one of the early
applications of solid state logic.
By comparison with today's control hardware, that stuff was pure buggy
whip, but it got the job done.
Lew
spaco wrote:
> Why don't they give tolerances on wooodworking projects and plans like
> they do for metalworking? Are there some tolerances that are so
> "standard" that everyone but me automatically knows them?
>
> Pete Stanaitis
Tolerances are most important in the area of joints. I think as long as
you hammer the nails to below the wood surface, that's fine. Paint can
fill small hammer dings, bondo fills the bigger ones, but they won't
hide protruding nail heads very well.
Silicone caulk smooths out the joints where the board ends don't match
up well or aren't square.
spaco wrote:
> Why don't they give tolerances on wooodworking projects and plans like
> they do for metalworking? Are there some tolerances that are so
> "standard" that everyone but me automatically knows them?
Hand tools (planes, chisels, scrapers) allow you to remove a thousandth
of an inch. This isn't usually important in overall dimensioning, but
can be useful for fitting joints.
Often people will assemble items and then plane/sand/scrape them
afterwards to ensure that everything that should be flush actually is.
Of course wood also moves, so some parts of joints are less critical
because you know that in a few weeks or months they won't be flush
anymore anyways.
Chris
Frank Arthur wrote:
> "Leonard Shapiro" <[email protected]> wrote in message
> news:[email protected]...
>> 1/6 of and inch is about as small as it gets in woodworking due to
>> wood movement
>>
>>
>>
>> Len
>> "
> Are you serious?
>
> I usually work in thousandths of an inch and try to keep most work
> within five thousandths for cabinet making work.
What kind of cabinet needs 1/200 tolerance? Heck, I wave a piece of
sandpaper at wood and it loses more than that :)
--
dadiOH
____________________________
dadiOH's dandies v3.06...
...a help file of info about MP3s, recording from
LP/cassette and tips & tricks on this and that.
Get it at http://mysite.verizon.net/xico
One of the beauties of specializing in Shaker style pieces is that being off
a little can be chalked up to aging and all those boogers in the finish lend
character to the distressed look.
I like it when a new piece looks 60 years old.
People always say I must be rally skilled to get that look. They don't know
it is due to a limited skillset.
"pete" <[email protected]> wrote in message
news:[email protected]...
> On Mon, 15 Sep 2008 09:02:02 -0500, spaco wrote:
>> Why don't they give tolerances on wooodworking projects and plans like
>> they do for metalworking? Are there some tolerances that are so
>> "standard" that everyone but me automatically knows them?
>>
>> Pete Stanaitis
>
> Leaving the "my tolerances are smaller than yours" brigade to carry
> on measuring each other! in practice, the tolerances are about the
> width of a pencil line. You can sharpen (or not) your point if you
> really need better than 1/2 mm or so.
> Most people just tighten the clamps a bit more if the tolerances
> don't work in their favour.
>
> Just my 2p worth.
On Sep 15, 8:02=A0am, spaco <[email protected]> wrote:
> Why don't they give tolerances on wooodworking projects and plans like
> they do for metalworking? =A0 Are there some tolerances that are so
> "standard" that everyone but me automatically knows them?
>
> Pete Stanaitis
Tolerances usually are included when drawings are submitted in an
industrial environment. You won't see tolerances in any hobbyist
magazines or books. The topic is "beyond their scope". But, if a
cabinet shop gets a set of drawings from an architect, there is
generally a definition of tolerances. Sometimes it is implied and
sometimes it is explicit. In general, tolerances are as follows
unless otherwise specified:
- Dimensions in fractions: +/- 1/64"
- Dimensions with one decimal place (X.X) +/- 0.10"
- Dimensions with two decimal places (X.XX) +/- 0.01"
- Dimensions with three decimal places (X.XXX) +/- 0.005"
- Dimensions with four decimal places (X.XXXX) +/- 0.003"
- Angles +/-0.5 degrees
You'll find drawings with tolerances in furniture factories (even for
the cheapie knock-down furniture). They will even have inspection
stations with SPC data collection and control charts. Just about any
environment where interchangeable parts are being made you'll see
drawings with tolerances. Ask Henry Ford why it doesn't pay to run a
factory full of "artisans" who insist on custom fitting everything.
If you can't read prints and build something to spec (with tolerances
like these), then you're probably better off working with designers
and consumers. Drawings from designers rarely include dimensions, let
alone tolerances. It's usually up to the craftsman to engineer the
solution from a sketch. And consumers want you to come up with the
drawings based on an idea in their head or pictures from magazines,
etc. In these cases you're on your own to figure out how much
accuracy is needed to produce the desired results.
The hobbyist making something from plans out of a magazine or book
usually gets dimensions but is pretty much on their own for everything
else. You learn by experience what needs to be accurate and what
doesn't.
Unique skills are required for success with all of these disciplines.
But, I wouldn't want to confuse "trial and error" with any of these
skills. It's better classified as a coping mechanism used by those
who need to develop some skills. It usually comes from having no idea
what accuracy is needed or how to produce it. You just try something
and see if it works. If it doesn't, you try again. You keep trying
until you get it right or you get fed up with getting it wrong so
often.
Ed Bennett
http://www.tablesawalignment.com
On Sep 15, 10:02=A0am, spaco <[email protected]> wrote:
> Why don't they give tolerances on wooodworking projects and plans like
> they do for metalworking? =A0 Are there some tolerances that are so
> "standard" that everyone but me automatically knows them?
>
> Pete Stanaitis
The simple answer to your question is because there is no need!
Seriously, it depends on a number of factors: type and expense of wood
being used, type of project, type of finish, how exposed part is going
to be, etc. For example, if pine is being used for say a distressed
pine table with a faux finish, there is plenty of leeway. On the
other hand, if I'm building a hardwood table with a clear or stained
finish, I will be very careful and precise.
"Chris Friesen" wrote:
> An accurate digital readout on the planer is really nice if you need
> to go back and make a new board to replace one that you've wrecked.
I prefer to use a hand held, digital caliper.
Measure the board you ant to duplicate, then run new board thru planer
in 1/16 increments, measuring as you go.
Final passes are 1/64.
You end up dead on for at least an hour<G>
Lew
I think you meant 1/16th, no?
Even that is quite a lot for many projects. For some even 1/32 is too much.
"Leonard Shapiro" <[email protected]> wrote in message
news:[email protected]...
> 1/6 of and inch is about as small as it gets in woodworking due to wood
> movement
>
>
>
> Len
> "
>
On Mon, 15 Sep 2008 21:25:55 -0600, Chris Friesen <[email protected]> wrote:
>dpb wrote:
>
>> Wonder how much different it is two hours later, what more the next
>> morning???
>
>If you start out with multiple boards of the same moisture content, then
>they're all pretty close to the same thickness the next morning,
>regardless of the actual dimensions. That's usually all that matters.
>
>An accurate digital readout on the planer is really nice if you need to
>go back and make a new board to replace one that you've wrecked.
>Measure the other boards, find another board with the same moisture
>content, and plane the new one to the thickness of the others.
>
>Chris
Wow.. I admire your precision...
This also reminds me why I'm a turner...
Ok, that one's round, what's the next project? lol
mac
Please remove splinters before emailing
"spaco" <[email protected]> wrote in message
news:[email protected]...
> Why don't they give tolerances on wooodworking projects and plans like
> they do for metalworking? Are there some tolerances that are so
> "standard" that everyone but me automatically knows them?
>
> Pete Stanaitis
If the part fits, it is in tolerance. Seriously, there is no need for a one
off item that most of us make to have a tolerance. If a table top is 36"
long or 35 63/64" or 36 1/8" does it make a difference? No. If a bench is
1/4" short of the plans, can your ass tell when you sit down? If you cut
one part wrong you usually can cut the fitting or mating part to the size
needed to mate properly.
If your factory is making bearings to fit crankshafts made by a different
factory, different story. Oh, those pistons better fit the block too.
Mortise and tenon joints are made to slip fit, but if they are all a little
over or under you adjust as needed.
On Mon, 15 Sep 2008 09:02:02 -0500, spaco <[email protected]>
wrote:
>Why don't they give tolerances on wooodworking projects and plans like
>they do for metalworking? Are there some tolerances that are so
>"standard" that everyone but me automatically knows them?
>
>Pete Stanaitis
Metal and wood are very different. Wood changes shape so tolerances
don't make sense. Understanding wood movement is crucial when making
larger projects if you want good results.
spaco wrote:
> Why don't they give tolerances on wooodworking projects and plans like
> they do for metalworking? Are there some tolerances that are so
> "standard" that everyone but me automatically knows them?
>
> Pete Stanaitis
In general, woodworking isn't dependent upon absolute measurements so much
as relative measurements. When jointing boards, 1/32 would be unacceptable
since one wants the joints "light-tight". On the other hand, 1/32 is way
ridiculous in overall project dimension tolerance. For joints, the
absolute dimensions don't make near as much difference as the dimension of
the joint components (mortise to tenon,etc.) relative to one another.
The nature of the material seems to drive this -- wood moves and changes
with humidity. It's better to work to relative fits than absolute
dimensions.
--
If you're going to be dumb, you better be tough
On Tue, 16 Sep 2008 19:45:41 -0700 (PDT), Ed Bennett
<[email protected]> wrote:
>- Dimensions in fractions: +/- 1/64"
>- Dimensions with one decimal place (X.X) +/- 0.10"
>- Dimensions with two decimal places (X.XX) +/- 0.01"
>- Dimensions with three decimal places (X.XXX) +/- 0.005"
>- Dimensions with four decimal places (X.XXXX) +/- 0.003"
>- Angles +/-0.5 degrees
Interesting.
Just for comparison, the standard (implied) tolerances on engineering
drawings at the aerospace firms I was associated with throughout my
career was X.XX +/- .03, and X.XXX +/- .010. Any tolerances other than
those, looser or tighter, had to be explicitly specified in the
dimension callout. Often those non-standard tolerances, and virtually
all 4 place dimensions, had to be justified to the group leader or
project engineer and, unless the need was obvious, would frequently be
questioned by the manufacturing engineers or planners.
Tom Veatch
Wichita, KS
USA
On Wed, 17 Sep 2008 00:07:22 GMT, "Jay R" <[email protected]> wrote:
>One of the beauties of specializing in Shaker style pieces is that being off
>a little can be chalked up to aging and all those boogers in the finish lend
>character to the distressed look.
>
>I like it when a new piece looks 60 years old.
>
>People always say I must be rally skilled to get that look. They don't know
>it is due to a limited skillset.
>
Hmmm... sounds like my marketing line when I tell them that each turning is
unique.. lol
mac
Please remove splinters before emailing
dadiOH wrote:
> What kind of cabinet needs 1/200 tolerance? Heck, I wave a piece of
> sandpaper at wood and it loses more than that :)
If you have edging on plywood that is 1/200" proud of the plywood, you
can easily feel it with your fingers. But you can also easily sand or
plane it flush.
The key with woodworking is not so much that individual pieces be
dimensioned that precisely, but that *matching* pieces be dimensioned
precisely. And this can be done post assembly, or by trial and error.
Chris
"Leonard Shapiro" <[email protected]> wrote in message
news:[email protected]...
> 1/6 of and inch is about as small as it gets in woodworking due to
> wood movement
>
>
>
> Len
> "
Are you serious?
I usually work in thousandths of an inch and try to keep most work
within five thousandths for cabinet making work. Most everything I use
is equipped with Digital Readouts attached to my Planer and other
tools.