I'm in a bit of a quandary.

I know how to machine this, but I don't know how to call it out on a
drawing.

I'm working on the mechanical drawings for a small electronic enclosure,
to modify a purchased case by drilling some holes for some connectors.

The holes are 1/2" diameter, and are on an end of the case that forms one
wall of a well: the other wall is formed by the molded-in battery box
about an inch away.

In order for the circuit board to fit, it must be tilted at about 40
degrees, the connectors that go through the above-mentioned holes are
inserted, pushed home as far as they'll go, then the whole shebang is
rotated into place.

In order for this to work, the top edges of the 1/2" holes need to be cut
at about a 40 degree angle. The end effect is that on the outside of the
case the holes are round, but on the inside they are oval.

Assuming that the above discussion makes sense, how would one call this
out on a drawing? Just draw the hole outlines, and leave it to the
machinist to figure out how to make it all work?

The case is ABS plastic, and the way that I'm making it is to machine the
holes on a mill, but make the 40 degree chamfer with an x-Acto knife.
But the case manufacturer is putting themselves forward to machine the
case for production. I'm going to send them a case with all the bits
installed, but I'd like to send them a drawing that could at least be
construed to be correct in some sense.

Suggestions welcome. Thanks.

--
My liberal friends think I'm a conservative kook.
My conservative friends think I'm a liberal kook.
Why am I not happy that they have found common ground?

Tim Wescott, Communications, Control, Circuits & Software
http://www.wescottdesign.com

"Tim Wescott" wrote in message
...

In order for the circuit board to fit, it must be tilted at about 40
degrees, the connectors that go through the above-mentioned holes
are
inserted, pushed home as far as they'll go, then the whole shebang
is
rotated into place.

In order for this to work, the top edges of the 1/2" holes need to
be cut
at about a 40 degree angle. The end effect is that on the outside
of the
case the holes are round, but on the inside they are oval.

Assuming that the above discussion makes sense, how would one call
this
out on a drawing? Just draw the hole outlines, and leave it to the
machinist to figure out how to make it all work?


You could add a cross-section drawing, open up the hole and use a thin
washer, or "see sample for detail".

The chassis casting drawing for a [mumble] is like the latter and I
had quite a hard time reconstructing the geometry of the battery
mounting bosses.

Tim Wescott wrote:
I'm in a bit of a quandary.

I know how to machine this, but I don't know how to call it out on a
drawing.

I'm working on the mechanical drawings for a small electronic enclosure,
to modify a purchased case by drilling some holes for some connectors.

The holes are 1/2" diameter, and are on an end of the case that forms one
wall of a well: the other wall is formed by the molded-in battery box
about an inch away.

In order for the circuit board to fit, it must be tilted at about 40
degrees, the connectors that go through the above-mentioned holes are
inserted, pushed home as far as they'll go, then the whole shebang is
rotated into place.

In order for this to work, the top edges of the 1/2" holes need to be cut
at about a 40 degree angle. The end effect is that on the outside of the
case the holes are round, but on the inside they are oval.

Assuming that the above discussion makes sense, how would one call this
out on a drawing? Just draw the hole outlines, and leave it to the
machinist to figure out how to make it all work?

The case is ABS plastic, and the way that I'm making it is to machine the
holes on a mill, but make the 40 degree chamfer with an x-Acto knife.
But the case manufacturer is putting themselves forward to machine the
case for production. I'm going to send them a case with all the bits
installed, but I'd like to send them a drawing that could at least be
construed to be correct in some sense.

Suggestions welcome. Thanks.


Do the holes have to be machined? I would think they could mold that
into the box using a retractable piece on that area of the mold.

Or if you want to machine it use a ball shaped cutter to plunge mill out
the hole, then move cutter up and use the back half to mill the relief area.


As for how to put that on the drawing. I would try.

Hole 1/2" bore located X / Y position.
Inner edge of hole to have a 40 degree relief chamfer from 90 - 270
degrees. (the degrees will be based on what you have to have. If you
only need the top 1/4 of the hole milled just call out the degrees needed)

--
Steve W.

"Tim Wescott" wrote in message
...
I'm in a bit of a quandary.

I know how to machine this, but I don't know how to call it out on a
drawing.

I'm working on the mechanical drawings for a small electronic enclosure,
to modify a purchased case by drilling some holes for some connectors.

The holes are 1/2" diameter, and are on an end of the case that forms one
wall of a well: the other wall is formed by the molded-in battery box
about an inch away.

In order for the circuit board to fit, it must be tilted at about 40
degrees, the connectors that go through the above-mentioned holes are
inserted, pushed home as far as they'll go, then the whole shebang is
rotated into place.

In order for this to work, the top edges of the 1/2" holes need to be cut
at about a 40 degree angle. The end effect is that on the outside of the
case the holes are round, but on the inside they are oval.

Assuming that the above discussion makes sense, how would one call this
out on a drawing? Just draw the hole outlines, and leave it to the
machinist to figure out how to make it all work?

The case is ABS plastic, and the way that I'm making it is to machine the
holes on a mill, but make the 40 degree chamfer with an x-Acto knife.
But the case manufacturer is putting themselves forward to machine the
case for production. I'm going to send them a case with all the bits
installed, but I'd like to send them a drawing that could at least be
construed to be correct in some sense.

Suggestions welcome. Thanks.


Section the main drawing and add a detail view that includes pertinient
features.

http://draftingmanuals.tpub.com/14040/css/14040_42.htm

SECT A-A D


--
My liberal friends think I'm a conservative kook.
My conservative friends think I'm a liberal kook.
Why am I not happy that they have found common ground?

Tim Wescott, Communications, Control, Circuits & Software
http://www.wescottdesign.com

Tim Wescott wrote:
I'm in a bit of a quandary.

I know how to machine this, but I don't know how to call it out on a
drawing.

I'm working on the mechanical drawings for a small electronic enclosure,
to modify a purchased case by drilling some holes for some connectors.

The holes are 1/2" diameter, and are on an end of the case that forms one
wall of a well: the other wall is formed by the molded-in battery box
about an inch away.

In order for the circuit board to fit, it must be tilted at about 40
degrees, the connectors that go through the above-mentioned holes are
inserted, pushed home as far as they'll go, then the whole shebang is
rotated into place.

In order for this to work, the top edges of the 1/2" holes need to be cut
at about a 40 degree angle. The end effect is that on the outside of the
case the holes are round, but on the inside they are oval.

Assuming that the above discussion makes sense, how would one call this
out on a drawing? Just draw the hole outlines, and leave it to the
machinist to figure out how to make it all work?

The case is ABS plastic, and the way that I'm making it is to machine the
holes on a mill, but make the 40 degree chamfer with an x-Acto knife.
But the case manufacturer is putting themselves forward to machine the
case for production. I'm going to send them a case with all the bits
installed, but I'd like to send them a drawing that could at least be
construed to be correct in some sense.

Suggestions welcome. Thanks.

Just be honest and note "crappy hackjob design, you have to wedge this
**** together, so flare the holes on one side."

Put that on the outside too, as a favor to anybody that might have to
service it later.

Using really short 9 volt battery leads with no strain relief would really
polish this thing off too. Slather it with hot glue or foil security
labels.

"Steve W." wrote in message
...
Tim Wescott wrote:
As for how to put that on the drawing. I would try.

Hole 1/2" bore located X / Y position.
Inner edge of hole to have a 40 degree relief chamfer from 90 - 270
degrees. (the degrees will be based on what you have to have. If
you only need the top 1/4 of the hole milled just call out the
degrees needed)
Steve W.

Would it hurt to chamfer the inside all the way around?
http://www.cogsdill.com/pdf/USCatalo...utBrochure.pdf

Or have the assembler file it as little as they have to?

On Mon, 18 Feb 2013 17:21:17 -0600, Tim Wescott
wrote:

I'm in a bit of a quandary.

I know how to machine this, but I don't know how to call it out on a
drawing.

I'm working on the mechanical drawings for a small electronic enclosure,
to modify a purchased case by drilling some holes for some connectors.

The holes are 1/2" diameter, and are on an end of the case that forms one
wall of a well: the other wall is formed by the molded-in battery box
about an inch away.

In order for the circuit board to fit, it must be tilted at about 40
degrees, the connectors that go through the above-mentioned holes are
inserted, pushed home as far as they'll go, then the whole shebang is
rotated into place.

In order for this to work, the top edges of the 1/2" holes need to be cut
at about a 40 degree angle. The end effect is that on the outside of the
case the holes are round, but on the inside they are oval.

Assuming that the above discussion makes sense, how would one call this
out on a drawing? Just draw the hole outlines, and leave it to the
machinist to figure out how to make it all work?

The case is ABS plastic, and the way that I'm making it is to machine the
holes on a mill, but make the 40 degree chamfer with an x-Acto knife.
But the case manufacturer is putting themselves forward to machine the
case for production. I'm going to send them a case with all the bits
installed, but I'd like to send them a drawing that could at least be
construed to be correct in some sense.

Suggestions welcome. Thanks.

Have you considered a Solidworks drawing?

On Tue, 19 Feb 2013 08:11:38 -0500, wrote:

On Mon, 18 Feb 2013 17:21:17 -0600, Tim Wescott
wrote:

I'm in a bit of a quandary.

I know how to machine this, but I don't know how to call it out on a
drawing.

I'm working on the mechanical drawings for a small electronic enclosure,
to modify a purchased case by drilling some holes for some connectors.

The holes are 1/2" diameter, and are on an end of the case that forms one
wall of a well: the other wall is formed by the molded-in battery box
about an inch away.

In order for the circuit board to fit, it must be tilted at about 40
degrees, the connectors that go through the above-mentioned holes are
inserted, pushed home as far as they'll go, then the whole shebang is
rotated into place.

In order for this to work, the top edges of the 1/2" holes need to be cut
at about a 40 degree angle. The end effect is that on the outside of the
case the holes are round, but on the inside they are oval.

Assuming that the above discussion makes sense, how would one call this
out on a drawing? Just draw the hole outlines, and leave it to the
machinist to figure out how to make it all work?

The case is ABS plastic, and the way that I'm making it is to machine the
holes on a mill, but make the 40 degree chamfer with an x-Acto knife.
But the case manufacturer is putting themselves forward to machine the
case for production. I'm going to send them a case with all the bits
installed, but I'd like to send them a drawing that could at least be
construed to be correct in some sense.

Suggestions welcome. Thanks.

Have you considered a Solidworks drawing?

A 3D model is even better than a drawing.

On Mon, 18 Feb 2013 19:37:42 -0500, Steve W. wrote:

Tim Wescott wrote:
I'm in a bit of a quandary.

I know how to machine this, but I don't know how to call it out on a
drawing.

I'm working on the mechanical drawings for a small electronic
enclosure, to modify a purchased case by drilling some holes for some
connectors.

The holes are 1/2" diameter, and are on an end of the case that forms
one wall of a well: the other wall is formed by the molded-in battery
box about an inch away.

In order for the circuit board to fit, it must be tilted at about 40
degrees, the connectors that go through the above-mentioned holes are
inserted, pushed home as far as they'll go, then the whole shebang is
rotated into place.

In order for this to work, the top edges of the 1/2" holes need to be
cut at about a 40 degree angle. The end effect is that on the outside
of the case the holes are round, but on the inside they are oval.

Assuming that the above discussion makes sense, how would one call this
out on a drawing? Just draw the hole outlines, and leave it to the
machinist to figure out how to make it all work?

The case is ABS plastic, and the way that I'm making it is to machine
the holes on a mill, but make the 40 degree chamfer with an x-Acto
knife. But the case manufacturer is putting themselves forward to
machine the case for production. I'm going to send them a case with
all the bits installed, but I'd like to send them a drawing that could
at least be construed to be correct in some sense.

Suggestions welcome. Thanks.


Do the holes have to be machined? I would think they could mold that
into the box using a retractable piece on that area of the mold.

Or if you want to machine it use a ball shaped cutter to plunge mill out
the hole, then move cutter up and use the back half to mill the relief
area.


As for how to put that on the drawing. I would try.

Hole 1/2" bore located X / Y position. Inner edge of hole to have a 40
degree relief chamfer from 90 - 270 degrees. (the degrees will be
based on what you have to have. If you only need the top 1/4 of the hole
milled just call out the degrees needed)

Thanks Steve.

It's for very low quantity -- if the product was of sufficient volume to
have a custom-molded case, I'd be hiring real mechanical engineering
talent, not marking up the manufacturer's drawing with my mods.

What you suggest is more or less what I've done, plus Jim's "see sample
for detail". I am, quite frankly, going to send off a sample to them
with a note that says "This part has been machined not only by an
engineer, but by an Electronics engineer. I expect to get back pieces
that correct all my mistakes. Thank you".

I almost didn't bother with drawings at all, except they've been a help
for me to get the holes located correctly, and to prove to myself that
the part can be made to be solid and good looking without custom molding.

--
My liberal friends think I'm a conservative kook.
My conservative friends think I'm a liberal kook.
Why am I not happy that they have found common ground?

Tim Wescott, Communications, Control, Circuits & Software
http://www.wescottdesign.com

On 2/19/2013 1:21, Tim Wescott wrote:
The case is ABS plastic, and the way that I'm making it is to machine the
holes on a mill, but make the 40 degree chamfer with an x-Acto knife.
But the case manufacturer is putting themselves forward to machine the
case for production. I'm going to send them a case with all the bits
installed, but I'd like to send them a drawing that could at least be
construed to be correct in some sense.

Suggestions welcome. Thanks.

Cross-section of the wall will show the angle..
Same "detail" cross-section can be used for all
holes with same dimensions.

It might be easier to make the hole 40 degrees
chamber to all directions - at least, allow that..
I would CNC machine it that way with a circular
cut of a 40 degrees cutter.. If they are cutting it
instead of punching it or such..

"Tim Wescott" wrote in message news:cP6dnW-

I almost didn't bother with drawings at all, except they've been a
help
for me to get the holes located correctly, and to prove to myself
that
the part can be made to be solid and good looking without custom
molding.

I designed the box with the line drawing feature of the PC board
program, as extra layers on the board artwork
http://www.mentor.com/products/pcb-s...gn-flows/pads/
..
That guaranteed a perfect match between them, which was important for
RF-tight microwave enclosures with many SMA connectors placed wherever
the electronic design rules forced them to be.

This Segway Balance Sensor Assembly was probably the hardest board I
did with the package represented by carefully placed line elements,
because of the angled, sloped daughter boards and poorly defined
three-dimensional clearance restrictions.
http://segwaynz.files.wordpress.com/...segway_bsa.jpg
http://www.smedirectory.net/myfolder...401a___100.jpg

It would have been easier if PADS could correctly import .dxfs from
Solidworks.

Tim Wescott wrote:
I'm in a bit of a quandary.

I know how to machine this, but I don't know how to call it out on a
drawing.

I'm working on the mechanical drawings for a small electronic enclosure,
to modify a purchased case by drilling some holes for some connectors.

The holes are 1/2" diameter, and are on an end of the case that forms one
wall of a well: the other wall is formed by the molded-in battery box
about an inch away.

In order for the circuit board to fit, it must be tilted at about 40
degrees, the connectors that go through the above-mentioned holes are
inserted, pushed home as far as they'll go, then the whole shebang is
rotated into place.

In order for this to work, the top edges of the 1/2" holes need to be cut
at about a 40 degree angle. The end effect is that on the outside of the
case the holes are round, but on the inside they are oval.

Assuming that the above discussion makes sense, how would one call this
out on a drawing? Just draw the hole outlines, and leave it to the
machinist to figure out how to make it all work?

The case is ABS plastic, and the way that I'm making it is to machine the
holes on a mill, but make the 40 degree chamfer with an x-Acto knife.
But the case manufacturer is putting themselves forward to machine the
case for production. I'm going to send them a case with all the bits
installed, but I'd like to send them a drawing that could at least be
construed to be correct in some sense.

Suggestions welcome. Thanks.


How thick is the wall these holes are going threw?

It seems to me that you should be doing one or more of the following:
1. Specifying the holes drilled at the 40 degree angle.
2. Increasing the diameter.
3. Raise the location of the holes a tiny bit

Stephen B
--
not that other Steve B That posts frequently

I think one can generate a plan view of any 3-D object with two rotations. Back before solid modeling this was accomplished by constructing projection views.

I designed a gimbal system with a similar geometry specifying the cut out for a connector in the round housing. I specified it by constructing a view parallel to the plan view of the connector defied by the angle the view was offset from the part front and top views. One can do the same thing with 2-D cad.

Engineering schools don’t teach 2-D drawing anymore so a lot of the new engineers lack geometric agility