Quick question regarding machining tolerances...

I need to indicate dimensional tolerance on a drawing.
A fork with 1.130 inside dim.

the tolerance is -0, +(what)?

Non critical precision.

..005?
..010?

--

Richard Lamb
http://www.home.earthlink.net/~cavelamb
http://www.home.earthlink.net/~sv_temptress

On 6/15/2011 4:54 PM, CaveLamb wrote:
Quick question regarding machining tolerances...

I need to indicate dimensional tolerance on a drawing.
A fork with 1.130 inside dim.

the tolerance is -0, +(what)?

Non critical precision.

.005?
.010?


The larger the tolerance, the cheaper it would cost to make, but really
depends on the application & how much slop would cause problems.

Can you describe in more detail? .010 thou may not be enough if whatever
metal (?) it is made from has a high expansion rate, or may be too much
for some parts, noise, hammering effects, etc...

MikeB

On Jun 15, 4:54*pm, CaveLamb wrote:
Quick question regarding machining tolerances...

I need to indicate dimensional tolerance on a drawing.
A fork with 1.130 inside dim.

the tolerance is -0, +(what)?

Non critical precision.

.005?
.010?

--

Richard Lambhttp://www.home.earthlink.net/~cavelambhttp://www.home.earthlink.net/~sv_temptress

If I remember correctly , unless otherwise indicated tolerances on
Aerospace dwg are +/- .030. Since one side is -0, reasonable
tolerance would be + .060.

Dan

wrote:
On Jun 15, 4:54 pm, CaveLamb wrote:
Quick question regarding machining tolerances...

I need to indicate dimensional tolerance on a drawing.
A fork with 1.130 inside dim.

the tolerance is -0, +(what)?

Non critical precision.

.005?
.010?

--

Richard Lambhttp://www.home.earthlink.net/~cavelambhttp://www.home.earthlink.net/~sv_temptress

If I remember correctly , unless otherwise indicated tolerances on
Aerospace dwg are +/- .030. Since one side is -0, reasonable
tolerance would be + .060.

Dan



Thanks all.
I don't think -0/+.060 wouldn't hurt anything.

Gooseneck fitting on the mast is about worn out.

Sad photos at:
http://www.home.earthlink.net/~sv_temptress/boom.htm

And no replacement parts available. Well, actually there is one,
but it has shrunk in the last 20 years! Doesn't fit, and is made
from lighter materials.

And no, I can't just relocate the new one. That would queer the
boat from class racing. They really are that strict.

One of the challenges of owning a rare boat, I guess.

Now a bigger challenge is to find someone who can fab it...


--

Richard Lamb
http://www.home.earthlink.net/~cavelamb
http://www.home.earthlink.net/~sv_temptress

On Jun 15, 6:18*pm, CaveLamb wrote:


Now a bigger challenge is to find someone who can fab it...

--

Richard Lambhttp://www.home.earthlink.net/~cavelambhttp://www.home.earthlink.net/~sv_temptress

Well Don Foreman was talking about needing some direction in his
life. And he has posted pictures of things he has made that looked
nice to me.

What is the gooseneck fitting made of? Could a bushing be made that
would restore the hole to the right size?

Dan

On Wed, 15 Jun 2011 17:18:22 -0500, CaveLamb
wrote:

wrote:
On Jun 15, 4:54 pm, CaveLamb wrote:
Quick question regarding machining tolerances...

I need to indicate dimensional tolerance on a drawing.
A fork with 1.130 inside dim.

the tolerance is -0, +(what)?

Non critical precision.

.005?
.010?

--

Richard Lambhttp://www.home.earthlink.net/~cavelambhttp://www.home.earthlink.net/~sv_temptress

If I remember correctly , unless otherwise indicated tolerances on
Aerospace dwg are +/- .030. Since one side is -0, reasonable
tolerance would be + .060.

Dan



Thanks all.
I don't think -0/+.060 wouldn't hurt anything.

Gooseneck fitting on the mast is about worn out.

Sad photos at:
http://www.home.earthlink.net/~sv_temptress/boom.htm

And no replacement parts available. Well, actually there is one,
but it has shrunk in the last 20 years! Doesn't fit, and is made
from lighter materials.

And no, I can't just relocate the new one. That would queer the
boat from class racing. They really are that strict.

One of the challenges of owning a rare boat, I guess.

Now a bigger challenge is to find someone who can fab it...


Why not simply reweld and remachine it? Its not rocket science. And its
only aluminum.

Hell..if you cant weld aluminum, machine it out and stick in a sleeve.

Gunner

--
Maxim 12: A soft answer turneth away wrath.
Once wrath is looking the other way, shoot it in the head.

wrote:
On Jun 15, 6:18 pm, CaveLamb wrote:

Now a bigger challenge is to find someone who can fab it...

--

Richard Lambhttp://www.home.earthlink.net/~cavelambhttp://www.home.earthlink.net/~sv_temptress

Well Don Foreman was talking about needing some direction in his
life. And he has posted pictures of things he has made that looked
nice to me.

What is the gooseneck fitting made of? Could a bushing be made that
would restore the hole to the right size?

Dan


That's way beyond my chop saw and file technology, of course.

It's 304 stainless.
There is no room inside the fork for anything, and there are
sometimes pretty hard bump loads, but basically it's a pin in fork.

The wear is strangely asymmetrical. The top hole is still nearly
round, although worn a bit larger, the bottom hole is nearly slotted
forward (toward the mast).


We have 55 boats in the association. A few of the other southern
boats have turned up a similar condition. Northern boats spend
more time out on the hard with the rig down, so they see less wear.
We may find enough demand in a few months to have a reasonable run made.
But for now, it's just mine I'm concerned aout.

I drew it up this morning to show the local machine shop.
But they close about the time I crawl out of bed...
I'll have to rise and shine a bit earlier.


The bushing idea, though...
The fingers are about .080 thick with a 1/4" hole.

I wonder how long JB Weld would last.



--

Richard Lamb
http://www.home.earthlink.net/~cavelamb
http://www.home.earthlink.net/~sv_temptress

On Wed, 15 Jun 2011 17:18:22 -0500, CaveLamb
wrote:

wrote:
On Jun 15, 4:54 pm, CaveLamb wrote:
Quick question regarding machining tolerances...

I need to indicate dimensional tolerance on a drawing.
A fork with 1.130 inside dim.

the tolerance is -0, +(what)?

Non critical precision.

.005?
.010?

--

Richard Lambhttp://www.home.earthlink.net/~cavelambhttp://www.home.earthlink.net/~sv_temptress

If I remember correctly , unless otherwise indicated tolerances on
Aerospace dwg are +/- .030. Since one side is -0, reasonable
tolerance would be + .060.

Dan



Thanks all.
I don't think -0/+.060 wouldn't hurt anything.

Gooseneck fitting on the mast is about worn out.

Sad photos at:
http://www.home.earthlink.net/~sv_temptress/boom.htm

And no replacement parts available. Well, actually there is one,
but it has shrunk in the last 20 years! Doesn't fit, and is made
from lighter materials.

And no, I can't just relocate the new one. That would queer the
boat from class racing. They really are that strict.

One of the challenges of owning a rare boat, I guess.

Now a bigger challenge is to find someone who can fab it...

Boom fittings usually don't have a very close fit - next larger size
drill bit sort of thing.

On Wed, 15 Jun 2011 19:47:57 -0500, CaveLamb
wrote:


That's way beyond my chop saw and file technology, of course.

It's 304 stainless.
There is no room inside the fork for anything, and there are
sometimes pretty hard bump loads, but basically it's a pin in fork.

Based on the photos..and based on the gooseneck on my Thistle..drilling
it out and putting in a hollow bushing should do the job.

Worked fine on my Thistle.

Gunner

--
Maxim 12: A soft answer turneth away wrath.
Once wrath is looking the other way, shoot it in the head.

On Jun 17, 11:47*pm, Steve Ackman
wrote:
...
* On submarines, for anything less than 6",
a three place decimal is +/- .005"
Two place decimal is +/- .010"
Fractional dimensions are +/- 1/64"
...

http://en.wikipedia.org/wiki/Tolerance_(engineering)

When I was a paper & pencil draftsman the title block tolerance was
0.005" for three places, 0.020 for two, unless otherwise specified. I
think they applied for aerospace parts at MITRE, though there I
usually drew my own title blocks on the CAD system and negotiated
tolerances with the vendor, to get as much as I could without paying
extra.

jsw