I sell to customers all the time who need to hold tolerances of 0.001"
or so while drilling, milling, reaming, etc. This is not extremely
difficult when you are talking about a single spindle device. However,
I sell multi drill spindle devices. ...sometimes with as many as 40
spindles.

One of the challenges I run across on a weekly basis is controlling
tolerances that closely on a head that has either a wide spread or many
spindles. The thermal growth of the head housing ranges significantly
from room temperature to operating temperature.

We have a few tricks to compensate for this including everything from
cooling fins to calculating the growth and specifying a warm up period
on the machine.

Knowing that there is an abundance of information contained in the
brains here, I thought I'd throw this out there and see if I got any new
ideas for us to try.

Here is a page showing a typical head for a Bridgeport:
http://www.drill-hq.com/?page_id=832

We never really know how the customer is going to use the device. Here
are some example scenarios:

Some folks put them on a simple drill press and spin them at low speed
because cycle time really doesn't matter. They turn off the drill press
between parts so the head never warms up.

Others will put them on a drill press, turn it on and run it at maximum
RPM for the duration of a shift. After 10 minutes, the head is at a
relatively stable operating temperature as long as they keep working
parts. If it spins freely, it cools down and shrinks.

The next guy may stick the head onto a Bridgeport or other style mill
and use it to drill holes one day and then pseudo-manually tap holes the
next. Drilling builds up more heat because of the RPMs involved and
thus on a wide head, the pattern can change a bit. Normally, this isn't
a problem, but on a really wide head, the end taps tend to bind a bit
and put side load on my device's spindles. Floating tap holders are not
really an option for industry standard ER style spindles - and that is
what I strive to use most of the time.

We may put a head on a self feeding drill unit. The customer may run the
head for one hour a day or 24 hours a day... We often don't know which
will take place as demand for the parts made by our units may change
overnight for some customers.

....The same basic challenges exist for CNC mounted heads or even direct
motor driven heads. We simply can't predict the growth of the head if
we can't figure out just how the head will actually be used.

So... Our goal is to simply take the thermal growth out of the
equation. Sometimes that is as simple as asking the customer to use
drill bushings or guides. Sometimes, we add cooling fins to the head
housing and ask them to run a fan on the housing whenever the head is
spinning. We have even gone so far as to bore holes through multiple
solid portions of the aluminum housing so the customer can pump liquid
coolant through the head at all times.

Some heads run in a shower or flood coolant atmosphere to control the
heat build-up...

we have tried steel housings, steel plates bolted to aluminum housings,
thin wall housings, thick wall housings, over sized housings, etc.
Anything we can think of to create a better atmosphere for either
physical control of the growth or management of heat build-up.

So... With all of that having been said, does anyone have any creative
ideas on how we might be able to solve this issue for some of our customers?

....Happy 2013 to everyone and much success in the new year!

--
http://tinyurl.com/My-Official-Response

Regards,
Joe Agro, Jr.
(800) 871-5022 x113
01.908.542.0244
Flagship Site: http://www.Drill-HQ.com
Automatic / Pneumatic Drills: http://www.AutoDrill.com
Multiple Spindle Drills: http://www.Multi-Drill.com
Production Tapping: http://www.Drill-HQ.com/?page_id=226
VIDEOS: http://www.youtube.com/user/AutoDrill
FACEBOOK: http://www.facebook.com/AutoDrill
TWITTER: http://twitter.com/AutoDrill

V8013-R

Let me add that one of the greatest challenges is keeping the guide rods
from binding up in situations such as I've mentioned above. I may sell
a 36" wide head with 1" guide rods at the ends... When the head grows a
few thousandths of an inch, the guide rods bind. Roller ball bushings
help, but still disintegrate quickly under such loads.

--
http://tinyurl.com/My-Official-Response

Regards,
Joe Agro, Jr.
(800) 871-5022 x113
01.908.542.0244
Flagship Site: http://www.Drill-HQ.com
Automatic / Pneumatic Drills: http://www.AutoDrill.com
Multiple Spindle Drills: http://www.Multi-Drill.com
Production Tapping: http://www.Drill-HQ.com/?page_id=226
VIDEOS: http://www.youtube.com/user/AutoDrill
FACEBOOK: http://www.facebook.com/AutoDrill
TWITTER: http://twitter.com/AutoDrill

V8013-R

On Fri, 28 Dec 2012 13:44:00 -0500, Joe AutoDrill
wrote:

I sell to customers all the time who need to hold tolerances of 0.001"
or so while drilling, milling, reaming, etc. This is not extremely
difficult when you are talking about a single spindle device. However,
I sell multi drill spindle devices. ...sometimes with as many as 40
spindles.

One of the challenges I run across on a weekly basis is controlling
tolerances that closely on a head that has either a wide spread or many
spindles. The thermal growth of the head housing ranges significantly
from room temperature to operating temperature.

We have a few tricks to compensate for this including everything from
cooling fins to calculating the growth and specifying a warm up period
on the machine.

Knowing that there is an abundance of information contained in the
brains here, I thought I'd throw this out there and see if I got any new
ideas for us to try.

Here is a page showing a typical head for a Bridgeport:
http://www.drill-hq.com/?page_id=832

We never really know how the customer is going to use the device. Here
are some example scenarios:

Some folks put them on a simple drill press and spin them at low speed
because cycle time really doesn't matter. They turn off the drill press
between parts so the head never warms up.

Others will put them on a drill press, turn it on and run it at maximum
RPM for the duration of a shift. After 10 minutes, the head is at a
relatively stable operating temperature as long as they keep working
parts. If it spins freely, it cools down and shrinks.

The next guy may stick the head onto a Bridgeport or other style mill
and use it to drill holes one day and then pseudo-manually tap holes the
next. Drilling builds up more heat because of the RPMs involved and
thus on a wide head, the pattern can change a bit. Normally, this isn't
a problem, but on a really wide head, the end taps tend to bind a bit
and put side load on my device's spindles. Floating tap holders are not
really an option for industry standard ER style spindles - and that is
what I strive to use most of the time.

We may put a head on a self feeding drill unit. The customer may run the
head for one hour a day or 24 hours a day... We often don't know which
will take place as demand for the parts made by our units may change
overnight for some customers.

...The same basic challenges exist for CNC mounted heads or even direct
motor driven heads. We simply can't predict the growth of the head if
we can't figure out just how the head will actually be used.

So... Our goal is to simply take the thermal growth out of the
equation. Sometimes that is as simple as asking the customer to use
drill bushings or guides. Sometimes, we add cooling fins to the head
housing and ask them to run a fan on the housing whenever the head is
spinning. We have even gone so far as to bore holes through multiple
solid portions of the aluminum housing so the customer can pump liquid
coolant through the head at all times.

Some heads run in a shower or flood coolant atmosphere to control the
heat build-up...

we have tried steel housings, steel plates bolted to aluminum housings,
thin wall housings, thick wall housings, over sized housings, etc.
Anything we can think of to create a better atmosphere for either
physical control of the growth or management of heat build-up.

So... With all of that having been said, does anyone have any creative
ideas on how we might be able to solve this issue for some of our customers?

...Happy 2013 to everyone and much success in the new year!
Greetings Joe,
At first thought, at least to me, the following idea seemed kind of
hokey, but maybe it will work. How about using a heater? Instead of
waiting for the head to heat up or having variable results in
different shops why not use a thermostat controlled heater? Then the
thing stays at some pre-determined temperature and tight tolerances
can be held.
Eric

On 12/28/2012 3:29 PM, wrote:

Greetings Joe,
At first thought, at least to me, the following idea seemed kind of
hokey, but maybe it will work. How about using a heater? Instead of
waiting for the head to heat up or having variable results in
different shops why not use a thermostat controlled heater? Then the
thing stays at some pre-determined temperature and tight tolerances
can be held.
Eric

See, that's the kind of stuff I would never think of on my own... Keep
'em coming!


--
http://tinyurl.com/My-Official-Response

Regards,
Joe Agro, Jr.
(800) 871-5022 x113
01.908.542.0244
Flagship Site: http://www.Drill-HQ.com
Automatic / Pneumatic Drills: http://www.AutoDrill.com
Multiple Spindle Drills: http://www.Multi-Drill.com
Production Tapping: http://www.Drill-HQ.com/?page_id=226
VIDEOS: http://www.youtube.com/user/AutoDrill
FACEBOOK: http://www.facebook.com/AutoDrill
TWITTER: http://twitter.com/AutoDrill

V8013-R

On Fri, 28 Dec 2012 13:44:00 -0500, Joe AutoDrill wrote:
I sell to customers all the time who need to hold tolerances of 0.001"
or so while drilling, milling, reaming, etc. This is not extremely
difficult when you are talking about a single spindle device. However,
I sell multi drill spindle devices. ...sometimes with as many as 40
spindles.

One of the challenges I run across on a weekly basis is controlling
tolerances that closely on a head that has either a wide spread or many
spindles. The thermal growth of the head housing ranges significantly
from room temperature to operating temperature.

We have a few tricks to compensate for this
[big snip]
So... With all of that having been said, does anyone have any creative
ideas on how we might be able to solve this issue for some of our customers?

I think creative ideas for this will be readily available, but practical
ideas much less so. Anyhow, here are some ideas, probably ranging from
slightly to totally impractical:

1, insulate a spindle-locating frame from the heat generating parts,
eg using ceramic spacers

2, add go/nogo indicators to the heads; eg have an insulated rod or a
Kevlar rod stretched between opposite ends of head, fastened at one end,
such that out-of-limits head expansion moves the other end far enough to
trip an indicator, or such that reaching operating temp moves it far
enough to turn on an indicator

3, add thermistors or thermocouples that control go/nogo indicators

4, make the spindle-locating frame out of a thermally-stable Kevlar
composite (see paragraph about Kevlar's slightly-negative
coefficient of axial thermal expansion, near the middle of
http://composite.about.com/od/aboutcompositesplastics/l/aa050597.htm)

5, active system: add a micrometric position-changer at each spindle,
eg hydraulic or piezoelectric or a moving wedge or screw-driven, along
with accurate temperature or position measuring feedback system

--
jiw

"James Waldby" wrote in message
...
On Fri, 28 Dec 2012 13:44:00 -0500, Joe AutoDrill wrote:
I sell to customers all the time who need to hold tolerances of 0.001"
or so while drilling, milling, reaming, etc. This is not extremely
difficult when you are talking about a single spindle device. However,
I sell multi drill spindle devices. ...sometimes with as many as 40
spindles.

One of the challenges I run across on a weekly basis is controlling
tolerances that closely on a head that has either a wide spread or many
spindles. The thermal growth of the head housing ranges significantly
from room temperature to operating temperature.

We have a few tricks to compensate for this
[big snip]
So... With all of that having been said, does anyone have any creative
ideas on how we might be able to solve this issue for some of our
customers?

I think creative ideas for this will be readily available, but practical
ideas much less so. Anyhow, here are some ideas, probably ranging from
slightly to totally impractical:

1, insulate a spindle-locating frame from the heat generating parts,
eg using ceramic spacers

2, add go/nogo indicators to the heads; eg have an insulated rod or a
Kevlar rod stretched between opposite ends of head, fastened at one end,
such that out-of-limits head expansion moves the other end far enough to
trip an indicator, or such that reaching operating temp moves it far
enough to turn on an indicator

3, add thermistors or thermocouples that control go/nogo indicators

4, make the spindle-locating frame out of a thermally-stable Kevlar
composite (see paragraph about Kevlar's slightly-negative
coefficient of axial thermal expansion, near the middle of
http://composite.about.com/od/aboutcompositesplastics/l/aa050597.htm)

5, active system: add a micrometric position-changer at each spindle,
eg hydraulic or piezoelectric or a moving wedge or screw-driven, along
with accurate temperature or position measuring feedback system



Usual procedure is to continuously wet everything including the quill
housing and so forth ( with spindles running ) with copius amounts of
cooolant that is being maintaned at steady temp of approximately 68F. via a
chiller loop.

If for some reason there is a shutdown say for instance over the weekend and
the temp drops, use electric resistance heating to first bring the coolant
reserve back to near setpoint and then restart the flooding process several
hours in advance.

"Joe AutoDrill" wrote in message
...
...The thermal growth of the head housing ranges significantly from
room temperature to operating temperature.

Didn't Monarch put a thermostatically controlled heater in some lathes
that stabilized them at at a constant operating temperature?
jsw

On Dec 28, 10:44*am, Joe AutoDrill wrote:
I sell to customers all the time who need to hold tolerances of 0.001"
or so while drilling, milling, reaming, etc. This is not extremely
difficult when you are talking about a single spindle device. *However,
I sell multi drill spindle devices. *...sometimes with as many as 40
spindles.

One of the challenges I run across on a weekly basis is controlling
tolerances that closely on a head that has either a wide spread or many
spindles. *The thermal growth of the head housing ranges significantly
from room temperature to operating temperature.

We have a few tricks to compensate for this including everything from
cooling fins to calculating the growth and specifying a warm up period
on the machine.

Knowing that there is an abundance of information contained in the
brains here, I thought I'd throw this out there and see if I got any new
ideas for us to try.

Here is a page showing a typical head for a Bridgeport:http://www.drill-hq.com/?page_id=832

We never really know how the customer is going to use the device. Here
are some example scenarios:

Some folks put them on a simple drill press and spin them at low speed
because cycle time really doesn't matter. They turn off the drill press
between parts so the head never warms up.

Others will put them on a drill press, turn it on and run it at maximum
RPM for the duration of a shift. *After 10 minutes, the head is at a
relatively stable operating temperature as long as they keep working
parts. *If it spins freely, it cools down and shrinks.

The next guy may stick the head onto a Bridgeport or other style mill
and use it to drill holes one day and then pseudo-manually tap holes the
next. *Drilling builds up more heat because of the RPMs involved and
thus on a wide head, the pattern can change a bit. *Normally, this isn't
a problem, but on a really wide head, the end taps tend to bind a bit
and put side load on my device's spindles. *Floating tap holders are not
really an option for industry standard ER style spindles - and that is
what I strive to use most of the time.

We may put a head on a self feeding drill unit. The customer may run the
head for one hour a day or 24 hours a day... *We often don't know which
will take place as demand for the parts made by our units may change
overnight for some customers.

...The same basic challenges exist for CNC mounted heads or even direct
motor driven heads. *We simply can't predict the growth of the head if
we can't figure out just how the head will actually be used.

So... *Our goal is to simply take the thermal growth out of the
equation. Sometimes that is as simple as asking the customer to use
drill bushings or guides. Sometimes, we add cooling fins to the head
housing and ask them to run a fan on the housing whenever the head is
spinning. *We have even gone so far as to bore holes through multiple
solid portions of the aluminum housing so the customer can pump liquid
coolant through the head at all times.

Some heads run in a shower or flood coolant atmosphere to control the
heat build-up...

we have tried steel housings, steel plates bolted to aluminum housings,
thin wall housings, thick wall housings, over sized housings, etc.
Anything we can think of to create a better atmosphere for either
physical control of the growth or management of heat build-up.

So... *With all of that having been said, does anyone have any creative
ideas on how we might be able to solve this issue for some of our customers?

...Happy 2013 to everyone and much success in the new year!

--http://tinyurl.com/My-Official-Response

Regards,
Joe Agro, Jr.
(800) 871-5022 x113
01.908.542.0244
Flagship Site:http://www.Drill-HQ.com
Automatic / Pneumatic Drills:http://www.AutoDrill.com
Multiple Spindle Drills:http://www.Multi-Drill.com
Production Tapping:http://www.Drill-HQ.com/?page_id=226
VIDEOS:http://www.youtube.com/user/AutoDrill
FACEBOOK:http://www.facebook.com/AutoDrill
TWITTER:http://twitter.com/AutoDrill

V8013-R

I have machined a ton of CMM parts out of Invar. Perhaps using Invar
can help you?

http://en.wikipedia.org/wiki/Invar

In article ,
Joe AutoDrill wrote:

Let me add that one of the greatest challenges is keeping the guide rods
from binding up in situations such as I've mentioned above. I may sell
a 36" wide head with 1" guide rods at the ends... When the head grows a
few thousandths of an inch, the guide rods bind. Roller ball bushings
help, but still disintegrate quickly under such loads.

In optical design, design for temperature independence is called
athermalization. There is a huge literature, part of which could be
relevant in that it involves using materials with different temperature
coefficients of linear expansion to passively adjust critical
dimensions. (The non-relevant part involves picking optical glasses
that have contrary variations in optical properties with temperature.)

In a linear array of axes, one would use aluminum and steel in
mechanical combination such that the inter-axis spacing doesn't change
even as the temperature of the assembly changes. One way to do this is
to have a steel frame with the spindle bearings attached to one long
wall by flexures, pushed via a second set of flexures from two aluminum
plates attached to the two short walls and parallel to the other long
wall. If one dimensions things correctly, the two expansion effects
will just cancel.

Joe Gwinn

Are you interested in two Dumore No. 24 automatic drilling heads?

i

On 2012-12-28, Joe AutoDrill wrote:
I sell to customers all the time who need to hold tolerances of 0.001"
or so while drilling, milling, reaming, etc. This is not extremely
difficult when you are talking about a single spindle device. However,
I sell multi drill spindle devices. ...sometimes with as many as 40
spindles.

One of the challenges I run across on a weekly basis is controlling
tolerances that closely on a head that has either a wide spread or many
spindles. The thermal growth of the head housing ranges significantly
from room temperature to operating temperature.

We have a few tricks to compensate for this including everything from
cooling fins to calculating the growth and specifying a warm up period
on the machine.

Knowing that there is an abundance of information contained in the
brains here, I thought I'd throw this out there and see if I got any new
ideas for us to try.

Here is a page showing a typical head for a Bridgeport:
http://www.drill-hq.com/?page_id=832

We never really know how the customer is going to use the device. Here
are some example scenarios:

Some folks put them on a simple drill press and spin them at low speed
because cycle time really doesn't matter. They turn off the drill press
between parts so the head never warms up.

Others will put them on a drill press, turn it on and run it at maximum
RPM for the duration of a shift. After 10 minutes, the head is at a
relatively stable operating temperature as long as they keep working
parts. If it spins freely, it cools down and shrinks.

The next guy may stick the head onto a Bridgeport or other style mill
and use it to drill holes one day and then pseudo-manually tap holes the
next. Drilling builds up more heat because of the RPMs involved and
thus on a wide head, the pattern can change a bit. Normally, this isn't
a problem, but on a really wide head, the end taps tend to bind a bit
and put side load on my device's spindles. Floating tap holders are not
really an option for industry standard ER style spindles - and that is
what I strive to use most of the time.

We may put a head on a self feeding drill unit. The customer may run the
head for one hour a day or 24 hours a day... We often don't know which
will take place as demand for the parts made by our units may change
overnight for some customers.

...The same basic challenges exist for CNC mounted heads or even direct
motor driven heads. We simply can't predict the growth of the head if
we can't figure out just how the head will actually be used.

So... Our goal is to simply take the thermal growth out of the
equation. Sometimes that is as simple as asking the customer to use
drill bushings or guides. Sometimes, we add cooling fins to the head
housing and ask them to run a fan on the housing whenever the head is
spinning. We have even gone so far as to bore holes through multiple
solid portions of the aluminum housing so the customer can pump liquid
coolant through the head at all times.

Some heads run in a shower or flood coolant atmosphere to control the
heat build-up...

we have tried steel housings, steel plates bolted to aluminum housings,
thin wall housings, thick wall housings, over sized housings, etc.
Anything we can think of to create a better atmosphere for either
physical control of the growth or management of heat build-up.

So... With all of that having been said, does anyone have any creative
ideas on how we might be able to solve this issue for some of our customers?

...Happy 2013 to everyone and much success in the new year!

Interesting idea. Rather than trying to keep the work at room temp, keep the
work predictably above room temp? Makes a lot of sense.

I was thinking some kind of cooling bath with circulator. Water has a high
heat capacity, compared to metals.

Christopher A. Young
Learn more about Jesus
www.lds.org
..

wrote in message
...
Greetings Joe,
At first thought, at least to me, the following idea seemed kind of
hokey, but maybe it will work. How about using a heater? Instead of
waiting for the head to heat up or having variable results in
different shops why not use a thermostat controlled heater? Then the
thing stays at some pre-determined temperature and tight tolerances
can be held.
Eric

On Fri, 28 Dec 2012 16:57:47 -0500, Joseph Gwinn wrote:

In article ,
Joe AutoDrill wrote:

Let me add that one of the greatest challenges is keeping the guide
rods from binding up in situations such as I've mentioned above. I may
sell a 36" wide head with 1" guide rods at the ends... When the head
grows a few thousandths of an inch, the guide rods bind. Roller ball
bushings help, but still disintegrate quickly under such loads.

In optical design, design for temperature independence is called
athermalization. There is a huge literature, part of which could be
relevant in that it involves using materials with different temperature
coefficients of linear expansion to passively adjust critical
dimensions. (The non-relevant part involves picking optical glasses
that have contrary variations in optical properties with temperature.)

In a linear array of axes, one would use aluminum and steel in
mechanical combination such that the inter-axis spacing doesn't change
even as the temperature of the assembly changes. One way to do this is
to have a steel frame with the spindle bearings attached to one long
wall by flexures, pushed via a second set of flexures from two aluminum
plates attached to the two short walls and parallel to the other long
wall. If one dimensions things correctly, the two expansion effects
will just cancel.

I considered mentioning something like that, but you'd need to make sure
that everything heats up the same, or at least in the same way.

Contrary scenario: You mount your spindles in aluminum, in a steel
frame. The dimensions stay the same over temperature as long as
everything is the same temperature. Now run the thing: The spindles heat
up, the aluminum expands, the spindle-to-spindle dimensions actually
_shrink_ before everything comes up to thermal equilibrium.

So -- your athermalization suggestion isn't to be dismissed, but it
should be approached with care.

--
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 Fri, 28 Dec 2012 12:29:24 -0800, etpm wrote:

On Fri, 28 Dec 2012 13:44:00 -0500, Joe AutoDrill
wrote:

I sell to customers all the time who need to hold tolerances of 0.001"
or so while drilling, milling, reaming, etc. This is not extremely
difficult when you are talking about a single spindle device. However,
I sell multi drill spindle devices. ...sometimes with as many as 40
spindles.

One of the challenges I run across on a weekly basis is controlling
tolerances that closely on a head that has either a wide spread or many
spindles. The thermal growth of the head housing ranges significantly
from room temperature to operating temperature.

We have a few tricks to compensate for this including everything from
cooling fins to calculating the growth and specifying a warm up period
on the machine.

Knowing that there is an abundance of information contained in the
brains here, I thought I'd throw this out there and see if I got any new
ideas for us to try.

Here is a page showing a typical head for a Bridgeport:
http://www.drill-hq.com/?page_id=832

We never really know how the customer is going to use the device. Here
are some example scenarios:

Some folks put them on a simple drill press and spin them at low speed
because cycle time really doesn't matter. They turn off the drill press
between parts so the head never warms up.

Others will put them on a drill press, turn it on and run it at maximum
RPM for the duration of a shift. After 10 minutes, the head is at a
relatively stable operating temperature as long as they keep working
parts. If it spins freely, it cools down and shrinks.

The next guy may stick the head onto a Bridgeport or other style mill
and use it to drill holes one day and then pseudo-manually tap holes the
next. Drilling builds up more heat because of the RPMs involved and
thus on a wide head, the pattern can change a bit. Normally, this isn't
a problem, but on a really wide head, the end taps tend to bind a bit
and put side load on my device's spindles. Floating tap holders are not
really an option for industry standard ER style spindles - and that is
what I strive to use most of the time.

We may put a head on a self feeding drill unit. The customer may run the
head for one hour a day or 24 hours a day... We often don't know which
will take place as demand for the parts made by our units may change
overnight for some customers.

...The same basic challenges exist for CNC mounted heads or even direct
motor driven heads. We simply can't predict the growth of the head if
we can't figure out just how the head will actually be used.

So... Our goal is to simply take the thermal growth out of the
equation. Sometimes that is as simple as asking the customer to use
drill bushings or guides. Sometimes, we add cooling fins to the head
housing and ask them to run a fan on the housing whenever the head is
spinning. We have even gone so far as to bore holes through multiple
solid portions of the aluminum housing so the customer can pump liquid
coolant through the head at all times.

Some heads run in a shower or flood coolant atmosphere to control the
heat build-up...

we have tried steel housings, steel plates bolted to aluminum housings,
thin wall housings, thick wall housings, over sized housings, etc.
Anything we can think of to create a better atmosphere for either
physical control of the growth or management of heat build-up.

So... With all of that having been said, does anyone have any creative
ideas on how we might be able to solve this issue for some of our
customers?

...Happy 2013 to everyone and much success in the new year!
Greetings Joe,
At first thought, at least to me, the following idea seemed kind of
hokey, but maybe it will work. How about using a heater? Instead of
waiting for the head to heat up or having variable results in different
shops why not use a thermostat controlled heater? Then the thing stays
at some pre-determined temperature and tight tolerances can be held.
Eric

That's a pretty common thing to do in high-precision oscillators for
electronics: the oscillator lives in an oven, which is maintained at
about five degrees C higher than the specified temperature of the
oscillator package. Any time the outside is colder than the inside, the
oven works to keep the inside temperature constant.

An alternative, that would use less power but more parts (and add design
grief), would be to equip the head with both fans and heat: when power is
applied, heat the head up to a bit higher than you ever expect with
maximum load and maximum ambient temperature. Then as the thing runs and
starts generating its own heat, first turn off the heaters, then turn on
the fans.

The advantage to this is that with a heat-only solution you've basically
got to design the sucker for August in Pheonix, which means its gonna be
HOT all the time. With the fan cooling you can at least design for fan-
cooled August in Pheonix.

--
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 2012-12-28, Joe AutoDrill wrote:
I sell to customers all the time who need to hold tolerances of 0.001"
or so while drilling, milling, reaming, etc. This is not extremely
difficult when you are talking about a single spindle device. However,
I sell multi drill spindle devices. ...sometimes with as many as 40
spindles.

One of the challenges I run across on a weekly basis is controlling
tolerances that closely on a head that has either a wide spread or many
spindles. The thermal growth of the head housing ranges significantly
from room temperature to operating temperature.

We have a few tricks to compensate for this including everything from
cooling fins to calculating the growth and specifying a warm up period
on the machine.

[ ... lots of information snipped ... ]

So... With all of that having been said, does anyone have any creative
ideas on how we might be able to solve this issue for some of our customers?

Well -- one thing which comes to mind is the way the higher
quality grandfather clocks were made. The sensitive part is the length
of the pendulum rod.

The trick which they used (at least one trick -- I don't think a
vial of mercury would help much here) is to have a harp of rods sort of
like this:

| | | | | | _______
=X==============================================X= / \
| | | | | | / \
=X=========================================X= | |
| | | | | | | |
================================================X= =X========| |
| | | | | | | |
=X=========================================X= | |
| | | | | | \ /
=X==============================================X= \_______/
| | | | | |

The left hand end goes up into the clock, and the right hand end is the
pendulum bob. (Sort of off scale.)

The intersections marked with 'X' are pinned or soldered to the crossbar

The middle rod, and the two outer ones are a material with a low thermal
coefficient of expansion, and the 2nd and 4th rods are a high
coefficient of expansion.

The spacing between the two main crossbars is selected so the
total expansion of the center and outer rods will be cancelled by the
expansion of the 2nd and 4th rods.

Now -- rods are not going to be rigid enough for your task, but
possibly alternate layers of differing metals could cause the distance
between the ends to stay pretty close to position. But this would
*only* correct the spacing between the center and the ends -- and not
any intermediate spindles. (I guess that you could mount two more
spindles halfway between the center and the end ones, and mesh the
quills with rack gears on either side, so they would travel half the
total expansion of the others. But with your 40-spindle heads, unless
you have a set of thermal sensors, and CNC to move each head as
appropriate, I just don't know. (Hmmm ... what is the TC for quartz?
fit optical scales on the quartz, floating the ends, and use CNC to move
each spindle to the right spacing based on the reading from the quartz
scales.) Way too expensive to be reasonable, but still a thought.

...Happy 2013 to everyone and much success in the new year!

And the same to you,
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 29 Dec 2012 00:32:38 GMT, "DoN. Nichols"
wrote:

On 2012-12-28, Joe AutoDrill wrote:
I sell to customers all the time who need to hold tolerances of 0.001"
or so while drilling, milling, reaming, etc. This is not extremely
difficult when you are talking about a single spindle device. However,
I sell multi drill spindle devices. ...sometimes with as many as 40
spindles.

One of the challenges I run across on a weekly basis is controlling
tolerances that closely on a head that has either a wide spread or many
spindles. The thermal growth of the head housing ranges significantly
from room temperature to operating temperature.

We have a few tricks to compensate for this including everything from
cooling fins to calculating the growth and specifying a warm up period
on the machine.

[ ... lots of information snipped ... ]

So... With all of that having been said, does anyone have any creative
ideas on how we might be able to solve this issue for some of our customers?

Well -- one thing which comes to mind is the way the higher
quality grandfather clocks were made. The sensitive part is the length
of the pendulum rod.

The trick which they used (at least one trick -- I don't think a
vial of mercury would help much here) is to have a harp of rods sort of
like this:

| | | | | | _______
=X==============================================X= / \
| | | | | | / \
=X=========================================X= | |
| | | | | | | |
================================================X = =X========| |
| | | | | | | |
=X=========================================X= | |
| | | | | | \ /
=X==============================================X= \_______/
| | | | | |

The left hand end goes up into the clock, and the right hand end is the
pendulum bob. (Sort of off scale.)

The intersections marked with 'X' are pinned or soldered to the crossbar

The middle rod, and the two outer ones are a material with a low thermal
coefficient of expansion, and the 2nd and 4th rods are a high
coefficient of expansion.

The spacing between the two main crossbars is selected so the
total expansion of the center and outer rods will be cancelled by the
expansion of the 2nd and 4th rods.

Now -- rods are not going to be rigid enough for your task, but
possibly alternate layers of differing metals could cause the distance
between the ends to stay pretty close to position. But this would
*only* correct the spacing between the center and the ends -- and not
any intermediate spindles. (I guess that you could mount two more
spindles halfway between the center and the end ones, and mesh the
quills with rack gears on either side, so they would travel half the
total expansion of the others. But with your 40-spindle heads, unless
you have a set of thermal sensors, and CNC to move each head as
appropriate, I just don't know. (Hmmm ... what is the TC for quartz?
fit optical scales on the quartz, floating the ends, and use CNC to move
each spindle to the right spacing based on the reading from the quartz
scales.) Way too expensive to be reasonable, but still a thought.

...Happy 2013 to everyone and much success in the new year!

And the same to you,
DoN.
Greetings DoN,
My first thought when reading Joe's post was what you describe above.
But I couldn't think of a simple, rigid and cheap way to implement it.
Then I though about how the real problem is one of variable
temperature and how to keep the temp constant. There are all kinds of
cooling schemes and some were mentioned. They all require power. Then
it hit me that a constant temperature didn't need to be 68F. It could
be whatever is convenient, which led me to think of cartridge heaters
and thermostats. They require power too but I bet the power consumed
would be pretty close to the power consumed by a cooling unit. Of
course having the drilling unit hot may contribute to an uncomfortable
environment during hot weather. I don't know how much heat would
actually need to be pumped into a particular unit. I can imagine a
large drilling unit mounted on a Bridgeport being operated manually
all day and the poor person using it sweating up a storm. On the other
hand it might be a bonus in the winter. Three points in the cartridge
heater favor: simple, pretty cheap, and widely available. Two points
against: waiting time to heat up and having a power cord. I'm sure
others can find more legitimate negatives. On the other hand Joe could
make the whole thing out of ZeroDur. That stuff hardly moves at all.
Kinda brittle though.
Eric

On Dec 28, 1:44*pm, Joe AutoDrill wrote:
I sell to customers all the time who need to hold tolerances of 0.001"
or so while drilling, milling, reaming, etc. This is not extremely
difficult when you are talking about a single spindle device. *However,
I sell multi drill spindle devices. *...sometimes with as many as 40
spindles.

One of the challenges I run across on a weekly basis is controlling
tolerances that closely on a head that has either a wide spread or many
spindles. *The thermal growth of the head housing ranges significantly
from room temperature to operating temperature.

We have a few tricks to compensate for this including everything from
cooling fins to calculating the growth and specifying a warm up period
on the machine.

Knowing that there is an abundance of information contained in the
brains here, I thought I'd throw this out there and see if I got any new
ideas for us to try.

Here is a page showing a typical head for a Bridgeport:http://www.drill-hq.com/?page_id=832

Nice thread, So there are a bunch of gears in there, turning all
the spindels?
I can't add much, but the obvious.
I assume you've done your best to
reduce the heat source.

Could you flow lubricating fluid through the gear body?
Reduce friction and carry the heat away, maybe?

George H.

We never really know how the customer is going to use the device. Here
are some example scenarios:

Some folks put them on a simple drill press and spin them at low speed
because cycle time really doesn't matter. They turn off the drill press
between parts so the head never warms up.

Others will put them on a drill press, turn it on and run it at maximum
RPM for the duration of a shift. *After 10 minutes, the head is at a
relatively stable operating temperature as long as they keep working
parts. *If it spins freely, it cools down and shrinks.

The next guy may stick the head onto a Bridgeport or other style mill
and use it to drill holes one day and then pseudo-manually tap holes the
next. *Drilling builds up more heat because of the RPMs involved and
thus on a wide head, the pattern can change a bit. *Normally, this isn't
a problem, but on a really wide head, the end taps tend to bind a bit
and put side load on my device's spindles. *Floating tap holders are not
really an option for industry standard ER style spindles - and that is
what I strive to use most of the time.

We may put a head on a self feeding drill unit. The customer may run the
head for one hour a day or 24 hours a day... *We often don't know which
will take place as demand for the parts made by our units may change
overnight for some customers.

...The same basic challenges exist for CNC mounted heads or even direct
motor driven heads. *We simply can't predict the growth of the head if
we can't figure out just how the head will actually be used.

So... *Our goal is to simply take the thermal growth out of the
equation. Sometimes that is as simple as asking the customer to use
drill bushings or guides. Sometimes, we add cooling fins to the head
housing and ask them to run a fan on the housing whenever the head is
spinning. *We have even gone so far as to bore holes through multiple
solid portions of the aluminum housing so the customer can pump liquid
coolant through the head at all times.

Some heads run in a shower or flood coolant atmosphere to control the
heat build-up...

we have tried steel housings, steel plates bolted to aluminum housings,
thin wall housings, thick wall housings, over sized housings, etc.
Anything we can think of to create a better atmosphere for either
physical control of the growth or management of heat build-up.

So... *With all of that having been said, does anyone have any creative
ideas on how we might be able to solve this issue for some of our customers?

...Happy 2013 to everyone and much success in the new year!

--http://tinyurl.com/My-Official-Response

Regards,
Joe Agro, Jr.
(800) 871-5022 x113
01.908.542.0244
Flagship Site:http://www.Drill-HQ.com
Automatic / Pneumatic Drills:http://www.AutoDrill.com
Multiple Spindle Drills:http://www.Multi-Drill.com
Production Tapping:http://www.Drill-HQ.com/?page_id=226
VIDEOS:http://www.youtube.com/user/AutoDrill
FACEBOOK:http://www.facebook.com/AutoDrill
TWITTER:http://twitter.com/AutoDrill

V8013-R

On Fri, 28 Dec 2012 15:34:57 -0500, Joe AutoDrill
wrote:

On 12/28/2012 3:29 PM, wrote:

Greetings Joe,
At first thought, at least to me, the following idea seemed kind of
hokey, but maybe it will work. How about using a heater? Instead of
waiting for the head to heat up or having variable results in
different shops why not use a thermostat controlled heater? Then the
thing stays at some pre-determined temperature and tight tolerances
can be held.
Eric

See, that's the kind of stuff I would never think of on my own... Keep
'em coming!

of course, your solution can't raise the cost much

Can you drill in water passages? Then sell a temp control unit to
those customers that need it. You could go from simple to
sophisticated here. Simple=solenoid+thermostat to city water

Water has 50X more cooling than fins to air.

In article ,
Tim Wescott wrote:

On Fri, 28 Dec 2012 16:57:47 -0500, Joseph Gwinn wrote:

In article ,
Joe AutoDrill wrote:

Let me add that one of the greatest challenges is keeping the guide
rods from binding up in situations such as I've mentioned above. I may
sell a 36" wide head with 1" guide rods at the ends... When the head
grows a few thousandths of an inch, the guide rods bind. Roller ball
bushings help, but still disintegrate quickly under such loads.

In optical design, design for temperature independence is called
athermalization. There is a huge literature, part of which could be
relevant in that it involves using materials with different temperature
coefficients of linear expansion to passively adjust critical
dimensions. (The non-relevant part involves picking optical glasses
that have contrary variations in optical properties with temperature.)

In a linear array of axes, one would use aluminum and steel in
mechanical combination such that the inter-axis spacing doesn't change
even as the temperature of the assembly changes. One way to do this is
to have a steel frame with the spindle bearings attached to one long
wall by flexures, pushed via a second set of flexures from two aluminum
plates attached to the two short walls and parallel to the other long
wall. If one dimensions things correctly, the two expansion effects
will just cancel.

I considered mentioning something like that, but you'd need to make sure
that everything heats up the same, or at least in the same way.

Contrary scenario: You mount your spindles in aluminum, in a steel
frame. The dimensions stay the same over temperature as long as
everything is the same temperature. Now run the thing: The spindles heat
up, the aluminum expands, the spindle-to-spindle dimensions actually
_shrink_ before everything comes up to thermal equilibrium.

So -- your athermalization suggestion isn't to be dismissed, but it
should be approached with care.

Yes. The devil is in the details. DoN's discussion of athermal
pendulum rods is a parallel example of mechanical athermalization.

To keep temperature uniform, I would fill the assembly with hydraulic
oil like Mobil DTE24 (thin enough that the operation of the mechanism
will keep the oil well stirred) such as used in the headstocks of
Clausing 5900-series lathes.

I also like the idea of a thermostatic heater to keep the assembly at a
constant higher temperature. Simple enough, but does require electrical
power.

Joe Gwinn

On 12/28/2012 5:40 PM, Ignoramus1442 wrote:
Are you interested in two Dumore No. 24 automatic drilling heads?

i


Unfortunately, not many people are. I get calls from folks looking to
replace them almost daily now because people can't get service, parts, etc.

If one calls with a #24 need, I'll shoot them in your direction.


--
http://tinyurl.com/My-Official-Response

Regards,
Joe Agro, Jr.
(800) 871-5022 x113
01.908.542.0244
Flagship Site: http://www.Drill-HQ.com
Automatic / Pneumatic Drills: http://www.AutoDrill.com
Multiple Spindle Drills: http://www.Multi-Drill.com
Production Tapping: http://www.Drill-HQ.com/?page_id=226
VIDEOS: http://www.youtube.com/user/AutoDrill
FACEBOOK: http://www.facebook.com/AutoDrill
TWITTER: http://twitter.com/AutoDrill

V8013-R

On 2013-01-02, Joe AutoDrill wrote:
On 12/28/2012 5:40 PM, Ignoramus1442 wrote:
Are you interested in two Dumore No. 24 automatic drilling heads?

i


Unfortunately, not many people are. I get calls from folks looking to
replace them almost daily now because people can't get service, parts, etc.

If one calls with a #24 need, I'll shoot them in your direction.



Thanks!

On 2013-01-02, Joe AutoDrill wrote:
On 12/28/2012 5:40 PM, Ignoramus1442 wrote:
Are you interested in two Dumore No. 24 automatic drilling heads?

i


Unfortunately, not many people are. I get calls from folks looking to
replace them almost daily now because people can't get service, parts, etc.

If one calls with a #24 need, I'll shoot them in your direction.



Thanks! Any idea what they are worth?

On 1/2/2013 10:09 AM, Ignoramus24272 wrote:
On 2013-01-02, Joe AutoDrill wrote:
On 12/28/2012 5:40 PM, Ignoramus1442 wrote:
Are you interested in two Dumore No. 24 automatic drilling heads?

i


Unfortunately, not many people are. I get calls from folks looking to
replace them almost daily now because people can't get service, parts, etc.

If one calls with a #24 need, I'll shoot them in your direction.



Thanks! Any idea what they are worth?


Honestly? Depends on the customer... One guy may need it and will be
willing to pay $1000+ for each one if they work well. The next guy
(more likely) is looking for parts and will pay $50 for them and
complain about the shipping...

It's like that with used self-feeders. They simply don't hold value
because they are often configured for a specific job, etc. That and
most of my competitors haven't a clue when it comes to post-sale
customer support on parts, etc. As their customer, you may have the
perfect machine, but if it's missing a widget, they can't figure out how
to sell it to you.

--
http://tinyurl.com/My-Official-Response

Regards,
Joe Agro, Jr.
(800) 871-5022 x113
01.908.542.0244
Flagship Site: http://www.Drill-HQ.com
Automatic / Pneumatic Drills: http://www.AutoDrill.com
Multiple Spindle Drills: http://www.Multi-Drill.com
Production Tapping: http://www.Drill-HQ.com/?page_id=226
VIDEOS: http://www.youtube.com/user/AutoDrill
FACEBOOK: http://www.facebook.com/AutoDrill
TWITTER: http://twitter.com/AutoDrill

V8013-R