I've got a situation where I have to drill 3 holes, then accurately
cut out a slot in the lid of a small cookie tin. I made the fixture pictured
here to do the deed:
http://www.flickr.com/photos/steambo...57624880649814
--The trick I came up with: I layed the thing out with a measuring
tape, making certain that the center of the round thing was a little over
some nice round numbers in X and Y, relative to a reference corner. Once
everything was drilled, tapped and fastened in place I put the fixture in
the vise with a part mounted. Using a dial indicator that touched the outer
rim I found the exact center of the part. I reset my DRO to 0,0 here and
then went looking for the edge of the fixture with an edge finder. I marked
down the numbers, then milled those two edges to 'round out' the distances.
Next time I use the fixture I know the center of the round thing is exactly
6" in X and 2" in Y, instead of some weird number I'd never remember.
--Still and all I'm not real happy with the fixture and I'd be
interested to know what others may have done in similar situations. I didn't
want to go overboard on design since I'm only doing maybe 50 of these and
the 'customer' is me. ;-)

--
"Steamboat Ed" Haas : Steel, Stainless, Titanium:
Hacking the Trailing Edge! : Guaranteed Uncertified Welding!
www.nmpproducts.com
---Decks a-wash in a sea of words---

"steamer" wrote in message
...
...
--Still and all I'm not real happy with the fixture and I'd be
interested to know what others may have done in similar situations. I
didn't
want to go overboard on design since I'm only doing maybe 50 of these and
the 'customer' is me. ;-)
"Steamboat Ed" Haas

Holtzapffel's suggestion for clamping oddly shaped artsy workpieces was a
custom wooden 'collet' closed by an external steel ring. The lids could use
an internal plug for support. I make such things out of either glued plywood
scraps or a chunk of firewood, depending on grain requirements. If it's
stationary you could close it with a Vise Grip chain wrench.

The wood doesn't scar the finish or damage cutters. Scrap credit cards like
AARP sends are good for padding finished or uneven work in a milling vise
too.

jsw

"steamer" wrote in message
...
I've got a situation where I have to drill 3 holes, then accurately
cut out a slot in the lid of a small cookie tin. I made the fixture pictured
here to do the deed:
http://www.flickr.com/photos/steambo...57624880649814
--The trick I came up with: I layed the thing out with a measuring
tape, making certain that the center of the round thing was a little over
some nice round numbers in X and Y, relative to a reference corner. Once
everything was drilled, tapped and fastened in place I put the fixture in
the vise with a part mounted. Using a dial indicator that touched the outer
rim I found the exact center of the part. I reset my DRO to 0,0 here and
then went looking for the edge of the fixture with an edge finder. I marked
down the numbers, then milled those two edges to 'round out' the distances.
Next time I use the fixture I know the center of the round thing is exactly
6" in X and 2" in Y, instead of some weird number I'd never remember.
--Still and all I'm not real happy with the fixture and I'd be
interested to know what others may have done in similar situations. I didn't
want to go overboard on design since I'm only doing maybe 50 of these and
the 'customer' is me. ;-)

For one-off's I've used plaster of paris to make a holding jig. It's readily
removed with just water. In your case could you spray a part with mold
release and fill it with bondo, or similar, to make the jig?
Art

On Wed, 31 Aug 2011 13:31:00 -0700, "Artemus"
wrote:


"steamer" wrote in message
...
I've got a situation where I have to drill 3 holes, then accurately
cut out a slot in the lid of a small cookie tin. I made the fixture pictured
here to do the deed:
http://www.flickr.com/photos/steambo...57624880649814
--The trick I came up with: I layed the thing out with a measuring
tape, making certain that the center of the round thing was a little over
some nice round numbers in X and Y, relative to a reference corner. Once
everything was drilled, tapped and fastened in place I put the fixture in
the vise with a part mounted. Using a dial indicator that touched the outer
rim I found the exact center of the part. I reset my DRO to 0,0 here and
then went looking for the edge of the fixture with an edge finder. I marked
down the numbers, then milled those two edges to 'round out' the distances.
Next time I use the fixture I know the center of the round thing is exactly
6" in X and 2" in Y, instead of some weird number I'd never remember.
--Still and all I'm not real happy with the fixture and I'd be
interested to know what others may have done in similar situations. I didn't
want to go overboard on design since I'm only doing maybe 50 of these and
the 'customer' is me. ;-)

For one-off's I've used plaster of paris to make a holding jig. It's readily
removed with just water. In your case could you spray a part with mold
release and fill it with bondo, or similar, to make the jig?
Art


You must be thinking of dry wall compound cause plaster of paris is
permanent, been playing with the stuff for the last couple of weeks.
Took awhile to figure out the correct mix again, probably have it
written down somewhere. Plus BTW, water first, drill, then powder!

Wood works for the OP, I milled a perpendicular round hole through
thin walled round tubing once. For those lids, I'd made a jig to have
it centered and clamp it from the top. Like a plywood disk screwed to
a rectangle of plywood that is left bolted to the table then one clamp
to hold it down the work.

I'm getting to the point of being afraid to throw anything away cause
there are so many alternate uses for things. Like yesterday I was
using one of those rubber spatula's for an extended finger to thread
in a bolt that I could only reach with one finger. Might as well toss
that one in here. Yesterday I was cutting up maple slabs and the
cheapy 2X3 table saw stopped while cutting two at a time. The motor is
bolted onto a approx. 2" X 3" steel box. Found the clip broke that
holds onto the brush holder. Tryed to duplicate the clip and gave up
and soldered the wrong wire to right holder. Got it all together and
as I plugged it in I said "What could possibly go wrong?" and it spun
the wrong direction. Took it apart again, plus had to drill out the
housing to punch out the blind bearing, and instead of re-soldering to
the other brush holder I turned the stator 180 degrees. Took about 3-4
hours, but It has lots of life left now.


SW

On 2011-09-02, Sunworshipper SW@GWNTUNDRA wrote:

[ ... ]

I'm getting to the point of being afraid to throw anything away cause
there are so many alternate uses for things. Like yesterday I was
using one of those rubber spatula's for an extended finger to thread
in a bolt that I could only reach with one finger.

Hmm ... in buying used electronic service toolkits, I wound up
with a set of spring-loaded thimbles with spring-loaded clips for various
sized hex nuts -- which is great for that particular task. (I have,
before, used double-sided tape to hold the nut to the fingertip.)

As for screws -- I've got both straight and Phillips screw
starters which have a twist-lock. You pushed the screw onto the end of
the driver and part of it rotates to lock the screw in place. For the
straight blade, it is the middle which rotates relative to the rest of
the blade. For the Phillips, one cross-blade rotates relative to the
other,a nd both have gripping surfaces. Obviously, these are useless
for applying much torque, but great for starting screws -- or for
picking screws out of recesses -- cock the driver, move it down onto the
screw head, and press. When it goes "snap" pull out screw and driver.

I haven't seen those in stores for years -- but presumably
someone still makes them.

Enjoy,
DoN.

--
Remove oil spill source from e-mail
Email: | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---

On Sep 3, 5:22*pm, "DoN. Nichols" wrote:
On 2011-09-02, Sunworshipper SW@GWNTUNDRA wrote:

* * * * [ ... ]

I'm getting to the point of being afraid to throw anything away cause
there are so many alternate uses for things. Like yesterday I was
using one of those rubber spatula's for an extended finger to thread
in a bolt that I could only reach with one finger.

* * * * Hmm ... in buying used electronic service toolkits, I wound up
with a set of spring-loaded thimbles with spring-loaded clips for various
sized hex nuts -- which is great for that particular task. *(I have,
before, used double-sided tape to hold the nut to the fingertip.) *

* * * * As for screws -- I've got both straight and Phillips screw
starters which have a twist-lock. *You pushed the screw onto the end of
the driver and part of it rotates to lock the screw in place. *For the
straight blade, it is the middle which rotates relative to the rest of
the blade. *For the Phillips, one cross-blade rotates relative to the
other,a nd both have gripping surfaces. *Obviously, these are useless
for applying much torque, but great for starting screws -- or for
picking screws out of recesses -- cock the driver, move it down onto the
screw head, and press. *When it goes "snap" pull out screw and driver.

* * * * I haven't seen those in stores for years -- but presumably
someone still makes them.

* * * * Enjoy,
* * * * * * * * DoN.

--
Used to be a staple item at the radio/TV supply places I used to go
to. Another business gone the way of the buggy whip. Had another sort
that worked better, a variation on the wedge driver for slotted
screws, where there's two right-angled petals that get expanded by a
plunger. That one really locked the Phillips and crosspoints in
place. I've see a smaller version at the local model railroad supply
where they've got lots of small specialty stuff like that.

Anymore, you can get really tiny rare earth magnets which solves the
problem of pulling trim screws out of deep holes. Useless for
nonmagnetic stainless and nylon numbers, but those are rarely in the
bottom of holes that deep. I use small disk magnets in sockets and
nutdrivers for starting nuts in the same circumstances. Particularly
handy where the bottom area is inaccessible and a dropped nut is gone
forever or worse, will get caught in the works.

Stan

On 2011-09-04, wrote:
On Sep 3, 5:22*pm, "DoN. Nichols" wrote:
On 2011-09-02, Sunworshipper SW@GWNTUNDRA wrote:

[ ... ]

* * * * As for screws -- I've got both straight and Phillips screw
starters which have a twist-lock. *You pushed the screw onto the end of
the driver and part of it rotates to lock the screw in place. *For the
straight blade, it is the middle which rotates relative to the rest of
the blade. *For the Phillips, one cross-blade rotates relative to the
other,a nd both have gripping surfaces. *Obviously, these are useless
for applying much torque, but great for starting screws -- or for
picking screws out of recesses -- cock the driver, move it down onto the
screw head, and press. *When it goes "snap" pull out screw and driver.

* * * * I haven't seen those in stores for years -- but presumably
someone still makes them.

[ ... ]

Used to be a staple item at the radio/TV supply places I used to go
to. Another business gone the way of the buggy whip. Had another sort
that worked better, a variation on the wedge driver for slotted
screws, where there's two right-angled petals that get expanded by a
plunger.

That sounds like a neat approach.

That one really locked the Phillips and crosspoints in
place. I've see a smaller version at the local model railroad supply
where they've got lots of small specialty stuff like that.

Hmm -- a No. 1 Phillips, a No. 2 Phillips, and perhaps a No. 3
Phillips and I would be happy there.

Anymore, you can get really tiny rare earth magnets which solves the
problem of pulling trim screws out of deep holes. Useless for
nonmagnetic stainless and nylon numbers, but those are rarely in the
bottom of holes that deep.

Unless they come from my drawers of screws. I've picked up
quite a few large bags of SS Phillips hardware at hamfests over the
years. :-)

I use small disk magnets in sockets and
nutdrivers for starting nuts in the same circumstances.

Except for brass nuts -- mostly found on terminal studs on the
back of D'Arsonval style meters, where magnetic materials are a no-no,
and places where the environment can be nasty -- as in telephone
junctions boxes on the outside of a house. (Actually, they used them
indoors a lot too, once upon a time.

Particularly
handy where the bottom area is inaccessible and a dropped nut is gone
forever or worse, will get caught in the works.

Or -- can cause short circuits down the road. I'm currently
working on a couple of old Tektronix 7000 series 'scopes right now. The
first one (a 7704), had bad (low resistance) 100 uF 18V electrolytic
capacitors in the power supply -- replaced, but other things are not
working right either Lots of things to trace out in that one. The other
one (a 7623 storage 'scope) has two 1800 uF 75VDC electrolytic caps
which appear to have gone open or dry, and I'm not sure that I can find
any of the same format (tab mount on PC board through holes like used to
be in old TV electrolytics), so I may have to do some creative
modification to mount something which will fit and work.

It was a major task, digging out an electronics workbench which
has been buried for about fifteen years (and which mice and a chipmunk
had used for a smorgasbord with acorns and sunflower seeds. :-)

Enjoy,
DoN.

--
Remove oil spill source from e-mail
Email: | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---

wrote in message
...
On Sep 3, 5:22 pm, "DoN. Nichols" wrote:
On 2011-09-02, Sunworshipper SW@GWNTUNDRA wrote:

[ ... ]

I'm getting to the point of being afraid to throw anything away cause
there are so many alternate uses for things. Like yesterday I was
using one of those rubber spatula's for an extended finger to thread
in a bolt that I could only reach with one finger.

Hmm ... in buying used electronic service toolkits, I wound up
with a set of spring-loaded thimbles with spring-loaded clips for various
sized hex nuts -- which is great for that particular task. (I have,
before, used double-sided tape to hold the nut to the fingertip.)

As for screws -- I've got both straight and Phillips screw
starters which have a twist-lock. You pushed the screw onto the end of
the driver and part of it rotates to lock the screw in place. For the
straight blade, it is the middle which rotates relative to the rest of
the blade. For the Phillips, one cross-blade rotates relative to the
other,a nd both have gripping surfaces. Obviously, these are useless
for applying much torque, but great for starting screws -- or for
picking screws out of recesses -- cock the driver, move it down onto the
screw head, and press. When it goes "snap" pull out screw and driver.

I haven't seen those in stores for years -- but presumably
someone still makes them.

Enjoy,
DoN.

--
Used to be a staple item at the radio/TV supply places I used to go
to. Another business gone the way of the buggy whip. Had another sort
that worked better, a variation on the wedge driver for slotted
screws, where there's two right-angled petals that get expanded by a
plunger. That one really locked the Phillips and crosspoints in
place. I've see a smaller version at the local model railroad supply
where they've got lots of small specialty stuff like that.

Anymore, you can get really tiny rare earth magnets which solves the
problem of pulling trim screws out of deep holes. Useless for
nonmagnetic stainless and nylon numbers, but those are rarely in the
bottom of holes that deep. I use small disk magnets in sockets and
nutdrivers for starting nuts in the same circumstances. Particularly
handy where the bottom area is inaccessible and a dropped nut is gone
forever or worse, will get caught in the works.

Stan

***************

I still have a couple from my tv/radio repair shop days of yore.
They're marked Quick Wedge and they have a site.
http://www.quickwedge.com/
Art

It seems as though the fixture clamps are toe-type pieces that are actually
clamping down on the rolled edge of the lid/workpiece.

Having a groove in the fixture baseplate for the rolled edge to partially
rest in, might be one feature that could be added fairly easily.

I prefer to have some backing material inside thinwall objects or materials
(typically plastic or sheetmetal workpieces), such as a plywood disk or ring
(pvc pipe section) placed inside the lid to give more wall support.

Wood backup material may be acceptable for 50 pieces, but I'm not familiar
with how hardwood or plywood reacts to flood lubricant/coolant.

Radiused internal aluminum pieces, secured to the baseplate would likely be
better for a longer production run, mounted in a way as to not have the
cutting tool run into a hardened screw head.

What function are the circuit boards when they're finished?

--
WB
..........


"steamer" wrote in message
...
I've got a situation where I have to drill 3 holes, then accurately
cut out a slot in the lid of a small cookie tin. I made the fixture
pictured
here to do the deed:
http://www.flickr.com/photos/steambo...57624880649814
--The trick I came up with: I layed the thing out with a measuring
tape, making certain that the center of the round thing was a little over
some nice round numbers in X and Y, relative to a reference corner. Once
everything was drilled, tapped and fastened in place I put the fixture in
the vise with a part mounted. Using a dial indicator that touched the
outer
rim I found the exact center of the part. I reset my DRO to 0,0 here and
then went looking for the edge of the fixture with an edge finder. I
marked
down the numbers, then milled those two edges to 'round out' the
distances.
Next time I use the fixture I know the center of the round thing is
exactly
6" in X and 2" in Y, instead of some weird number I'd never remember.
--Still and all I'm not real happy with the fixture and I'd be
interested to know what others may have done in similar situations. I
didn't
want to go overboard on design since I'm only doing maybe 50 of these and
the 'customer' is me. ;-)

--
"Steamboat Ed" Haas : Steel, Stainless, Titanium:
Hacking the Trailing Edge! : Guaranteed Uncertified Welding!
www.nmpproducts.com
---Decks a-wash in a sea of words---

Wild_Bill wrote:
It seems as though the fixture clamps are toe-type pieces that are actually
clamping down on the rolled edge of the lid/workpiece.
--Yes.

Wood backup material may be acceptable for 50 pieces, but I'm not familiar
with how hardwood or plywood reacts to flood lubricant/coolant.
--Not too badly with a coating of Bondo and mold release first.

Radiused internal aluminum pieces, secured to the baseplate would likely be
better for a longer production run, mounted in a way as to not have the
cutting tool run into a hardened screw head.
--Ack; think I'll go with wood for this short a run.

What function are the circuit boards when they're finished?
--Something I couldn't find commercially so am making instead: a low
speed tachometer. Most tachs read in thousands with resolution in hundreds.
This reads resolution of 1 to 5 rpm. I made it for my boat's steam engine. I
can count with a stopwatch up to about 300 but beyond that I'm stuck. Engine
runs sweetest a little over 400rpm so I need a tach to do it right. The
trouble with the bicycle variety is the crappy display; mine's got a nice,
bright readable display that I can read at night and in sunlight.




--
"Steamboat Ed" Haas : Steel, Stainless, Titanium:
Hacking the Trailing Edge! : Guaranteed Uncertified Welding!
www.nmpproducts.com
---Decks a-wash in a sea of words---

On Thursday, September 1, 2011 at 2:53:34 AM UTC-7, Wild_Bill wrote:

What function are the circuit boards when they're finished?
--Once we get the bugs worked out they're low speed tachometers. Range will be from around 2 to 3,000 rpm.