One of our customers with a special three spindle drilling head is having
some problems. They went out and bought a drill press that can not get the
RPM / thrust settings right for a particular drilling process they need to
run.

Rather than buy a new drill press, they bought some tooling that can handle
the higher feed rate per revolution.

The head is being used to drill 2 holes at 0.326" diameter and one hole at
0.218" diameter. The material is stainless steel and their machine makes a
lot of thrust. They can not reduce the thrust or increase the RPM unless
they buy a new drill press and of course, they are resisting that idea
because the drill press they would need to buy (probably a used Bridgeport
actually) costs much more than the head I sold them.

The bearings inside the head do not last very long because they are being
pushed way past their thrust ratings. Because of the close C-C spacing,
there are no larger bearings or "stacked" bearing options available to me at
this time without actually building them a brand new drilling head. They
are open to this as the fault here is clear - they need the proper machine
to drive the head...

But... Before we go down either the new and more robust head route or new
machine to drive the head route... I'm wondering if there are any bearing
experts out here who can tell me whether there are any specialty bearings
that take higher thrust numbers or even vibration better than a typical ABEC
1 bearing. I was thinking ceramic, but I don't think they would take
vibration very well... We were thinking of going to higher ABEC numbers on
the bearings but I'm not sure that will help either s it shows higher RPM
ratings, but not much difference in thrust ratings.

Before anyone asks, we can't change the input/output RPM of the head to
compensate either. If I could simply have the inpututput at 1:2, that
would solve it, but there is no room for the gearing inside their footprint
to do that...

Random thoughts from the wild welcomed! We have two solutions as noted
above, but the customer would like to avoid both if possible...

Regards,
Joe Agro, Jr.
(800) 871-5022
01.908.542.0244
Automatic / Pneumatic Drills: http://www.AutoDrill.com
Multiple Spindle Drills: http://www.Multi-Drill.com
Flagship Site: http://www.Drill-N-Tap.com

V8013-R

In article ,
"Joe AutoDrill" wrote:

Random thoughts from the wild welcomed! We have two solutions as noted
above, but the customer would like to avoid both if possible...

Well, I don't claim to be an expert, but I am a throwback at various
times, and sometimes being a throwback is a good thing.

Without a picture/drawing to work from, I'm sort of flailing in the dark
here a bit, but it sounds like you are using ball bearings, and probably
depending on them for taking the thrust load sideways.

And you say you don't have space, so doing something like putting in a
dedicated roller thrust bearing is out, and using tapered roller
bearings is out.

But you might be able to use plain bronze, or Oilite. Plain bronze takes
higher loads. You're at low speed, high thrust, which is a good realm
for bronze. It might mean having to actually oil things, but plain
bearings do take considerable loads better than point contact bearings...

Again, flailing in the dark, you'll probably have to custom machine such
bearings to take both loads in the limited space available, but that
should be possible, I think.

Then again, I'm no expert.

--
Cats, coffee, chocolate...vices to live by

"Ecnerwal" wrote in message
...
In article ,
"Joe AutoDrill" wrote:

Random thoughts from the wild welcomed! We have two solutions as noted
above, but the customer would like to avoid both if possible...

Well, I don't claim to be an expert, but I am a throwback at various
times, and sometimes being a throwback is a good thing.

Without a picture/drawing to work from, I'm sort of flailing in the dark
here a bit, but it sounds like you are using ball bearings, and probably
depending on them for taking the thrust load sideways.

And you say you don't have space, so doing something like putting in a
dedicated roller thrust bearing is out, and using tapered roller
bearings is out.

But you might be able to use plain bronze, or Oilite. Plain bronze takes
higher loads. You're at low speed, high thrust, which is a good realm
for bronze. It might mean having to actually oil things, but plain
bearings do take considerable loads better than point contact bearings...

Again, flailing in the dark, you'll probably have to custom machine such
bearings to take both loads in the limited space available, but that
should be possible, I think.

Then again, I'm no expert.

--


agree with above - sleeve bushings will take dramatically higher loads than
a ball bearing - consider a proper material with pressure lubrication - the
specialty suppliers can help you select the material. If you have room for
ball bearings you have room for bushings and lubrication plumbing.

On Fri, 27 Feb 2009 10:45:02 -0500, "Joe AutoDrill"
wrote:



The bearings inside the head do not last very long because they are being
pushed way past their thrust ratings. Because of the close C-C spacing,
there are no larger bearings or "stacked" bearing options available to me at
this time without actually building them a brand new drilling head. They
are open to this as the fault here is clear - they need the proper machine
to drive the head...

But... Before we go down either the new and more robust head route or new
machine to drive the head route... I'm wondering if there are any bearing
experts out here who can tell me whether there are any specialty bearings
that take higher thrust numbers or even vibration better than a typical ABEC
1 bearing. I was thinking ceramic, but I don't think they would take
vibration very well... We were thinking of going to higher ABEC numbers on
the bearings but I'm not sure that will help either s it shows higher RPM
ratings, but not much difference in thrust ratings.

Assuming you're using standard deep groove bearings (62xx, 63xx,
etc.), the most obvious solution is to replace them with angular
contact bearings (72xx, 73xx). Angular contact bearings are better
suited to handling combined axial and radial loads, especially where
thrust predominates. But, there are fewer choices of sizes and
sealing/shielding available.

If you can't easily make a size-for-size swap, specifying deep groove
bearings with a larger than normal internal clearance will give you
some additional thrust capacity. The internal clearance is specified
independently of ABEC class, usually with a C plus a number. There is
no consistent nomenclature between mfrs, so speak to a supplier you
trust or directly to the mfr's tech support before concluding that one
mfr's C3 is looser than another's C0. SKF has always been helpful when
I've had a question.

Larger internal clearance in a deep groove bearing allows the balls to
ride higher on the race's walls. This will put the contact points
between the balls and races more in line with an axial load, which is
what an angular contact bearing is designed to do.

--
Ned Simmons

"Joe AutoDrill" wrote in message
...
One of our customers with a special three spindle drilling head is having
some problems. They went out and bought a drill press that can not get
the
RPM / thrust settings right for a particular drilling process they need to
run.

Rather than buy a new drill press, they bought some tooling that can
handle
the higher feed rate per revolution.
snip

On one of our multi-drill set-ups, rather than use the built in feed on the
Clausing drill press, we have an air cylinder pushing the spindle from the
top using a live center. We vary the feed pressure with a regulator.
Simple and haven't had any issues. We are blessed with a couple of used
machinery dealers around here. This Clausing was a couple hundred bucks.

For a quick and relatively cheap solution, I would try having the stock
bearings superfinished and coated by MicroBlue:
http://www.microblueracing.com/beari...r_bearings.php


"Joe AutoDrill" wrote in message
...
One of our customers with a special three spindle drilling head is having
some problems. They went out and bought a drill press that can not get
the
RPM / thrust settings right for a particular drilling process they need to
run.

Rather than buy a new drill press, they bought some tooling that can
handle
the higher feed rate per revolution.

The head is being used to drill 2 holes at 0.326" diameter and one hole
at
0.218" diameter. The material is stainless steel and their machine makes
a
lot of thrust. They can not reduce the thrust or increase the RPM unless
they buy a new drill press and of course, they are resisting that idea
because the drill press they would need to buy (probably a used Bridgeport
actually) costs much more than the head I sold them.

The bearings inside the head do not last very long because they are being
pushed way past their thrust ratings. Because of the close C-C spacing,
there are no larger bearings or "stacked" bearing options available to me
at this time without actually building them a brand new drilling head.
They are open to this as the fault here is clear - they need the proper
machine to drive the head...

But... Before we go down either the new and more robust head route or new
machine to drive the head route... I'm wondering if there are any bearing
experts out here who can tell me whether there are any specialty bearings
that take higher thrust numbers or even vibration better than a typical
ABEC 1 bearing. I was thinking ceramic, but I don't think they would take
vibration very well... We were thinking of going to higher ABEC numbers
on the bearings but I'm not sure that will help either s it shows higher
RPM ratings, but not much difference in thrust ratings.

Before anyone asks, we can't change the input/output RPM of the head to
compensate either. If I could simply have the inpututput at 1:2, that
would solve it, but there is no room for the gearing inside their
footprint to do that...

Random thoughts from the wild welcomed! We have two solutions as noted
above, but the customer would like to avoid both if possible...

Regards,
Joe Agro, Jr.
(800) 871-5022
01.908.542.0244
Automatic / Pneumatic Drills: http://www.AutoDrill.com
Multiple Spindle Drills: http://www.Multi-Drill.com
Flagship Site: http://www.Drill-N-Tap.com

V8013-R

"Joe AutoDrill" wrote in message
...
One of our customers with a special three spindle drilling head is having
some problems.

How are the bearings failing, Joe? Are the balls spalling, or the races, or
is it a case of the races getting worn?

It sounds like it's a specific-load issue, rather than a finish or precision
issue, so better-quality steel bearings probably won't help. You have to get
the specific load down to something acceptable. Plain bearings will do it,
but maybe there's some kind of tapered roller that will fit. That would
reduce the specific load a great deal.

--
Ed Huntress

Joe AutoDrill wrote:

One of our customers with a special three spindle drilling head is having
some problems. They went out and bought a drill press that can not get the
RPM / thrust settings right for a particular drilling process they need to
run.

Rather than buy a new drill press, they bought some tooling that can handle
the higher feed rate per revolution.

The head is being used to drill 2 holes at 0.326" diameter and one hole at
0.218" diameter. The material is stainless steel and their machine makes a
lot of thrust. They can not reduce the thrust or increase the RPM unless
they buy a new drill press and of course, they are resisting that idea
because the drill press they would need to buy (probably a used Bridgeport
actually) costs much more than the head I sold them.

The bearings inside the head do not last very long because they are being
pushed way past their thrust ratings. Because of the close C-C spacing,
there are no larger bearings or "stacked" bearing options available to me at
this time without actually building them a brand new drilling head. They
are open to this as the fault here is clear - they need the proper machine
to drive the head...

But... Before we go down either the new and more robust head route or new
machine to drive the head route... I'm wondering if there are any bearing
experts out here who can tell me whether there are any specialty bearings
that take higher thrust numbers or even vibration better than a typical ABEC
1 bearing. I was thinking ceramic, but I don't think they would take
vibration very well... We were thinking of going to higher ABEC numbers on
the bearings but I'm not sure that will help either s it shows higher RPM
ratings, but not much difference in thrust ratings.

Before anyone asks, we can't change the input/output RPM of the head to
compensate either. If I could simply have the inpututput at 1:2, that
would solve it, but there is no room for the gearing inside their footprint
to do that...

Random thoughts from the wild welcomed! We have two solutions as noted
above, but the customer would like to avoid both if possible...

Regards,
Joe Agro, Jr.
(800) 871-5022
01.908.542.0244
Automatic / Pneumatic Drills: http://www.AutoDrill.com
Multiple Spindle Drills: http://www.Multi-Drill.com
Flagship Site: http://www.Drill-N-Tap.com

V8013-R

I'm a bit confused about where the problem lies. What is controlling the
thrust? The drill press is supplying the rotation power and spindle, but
what is driving the spindle or heads travel / thrust? It would seem that
it would be separately controllable. Is it a travel per revolution
thing, and if so can you rework the drive ratio to that?

On 2009-02-27, Buerste wrote:
On one of our multi-drill set-ups, rather than use the built in feed on the
Clausing drill press, we have an air cylinder pushing the spindle from the
top using a live center. We vary the feed pressure with a regulator.
Simple and haven't had any issues. We are blessed with a couple of used
machinery dealers around here. This Clausing was a couple hundred bucks.

I think that we have a winner here.
--
Due to extreme spam originating from Google Groups, and their inattention
to spammers, I and many others block all articles originating
from Google Groups. If you want your postings to be seen by
more readers you will need to find a different means of
posting on Usenet.
http://improve-usenet.org/

On one of our multi-drill set-ups, rather than use the built in feed on
the Clausing drill press, we have an air cylinder pushing the spindle from
the top using a live center. We vary the feed pressure with a regulator.
Simple and haven't had any issues. We are blessed with a couple of used
machinery dealers around here. This Clausing was a couple hundred bucks.

LOL... That's essentially a home made version of my AutoDrill. I'd love to
sell him my AutoDrill for the process, but if he won't buy another DP, he
certainly won't buy an automatic drill.

They might be able to retrofit an air cylinder like you did though...
--


Regards,
Joe Agro, Jr.
(800) 871-5022
01.908.542.0244
Automatic / Pneumatic Drills: http://www.AutoDrill.com
Multiple Spindle Drills: http://www.Multi-Drill.com
Flagship Site: http://www.Drill-N-Tap.com

V8013-R

I'm a bit confused about where the problem lies. What is controlling the
thrust? The drill press is supplying the rotation power and spindle, but
what is driving the spindle or heads travel / thrust? It would seem that
it would be separately controllable. Is it a travel per revolution
thing, and if so can you rework the drive ratio to that?

Gear head drill press. The RPM that the drills need to run at (maximum) is
too slow for the lowest feed rate the machine offers. They can't lower the
feed rate and can't speed up the RPM so they play with funny tooling to make
it work... but then the extra feed rate at the slow RPM causes a tremendous
load on the drilling head.

I'm waiting for photos / bad parts to know exactly what it is doing to the
bearings...

Regards,
Joe Agro, Jr.
(800) 871-5022
01.908.542.0244
Automatic / Pneumatic Drills: http://www.AutoDrill.com
Multiple Spindle Drills: http://www.Multi-Drill.com
Flagship Site: http://www.Drill-N-Tap.com

V8013-R

Ned Simmons posted
in
rec.crafts.metalworking on Fri, 27 Feb 2009 11:18:52 -0500:

On Fri, 27 Feb 2009 10:45:02 -0500, "Joe AutoDrill"
wrote:



The bearings inside the head do not last very long because they are being
pushed way past their thrust ratings. Because of the close C-C spacing,
there are no larger bearings or "stacked" bearing options available to me at
this time without actually building them a brand new drilling head. They
are open to this as the fault here is clear - they need the proper machine
to drive the head...

But... Before we go down either the new and more robust head route or new
machine to drive the head route... I'm wondering if there are any bearing
experts out here who can tell me whether there are any specialty bearings
that take higher thrust numbers or even vibration better than a typical ABEC
1 bearing. I was thinking ceramic, but I don't think they would take
vibration very well... We were thinking of going to higher ABEC numbers on
the bearings but I'm not sure that will help either s it shows higher RPM
ratings, but not much difference in thrust ratings.

Assuming you're using standard deep groove bearings (62xx, 63xx,
etc.), the most obvious solution is to replace them with angular
contact bearings (72xx, 73xx). Angular contact bearings are better
suited to handling combined axial and radial loads, especially where
thrust predominates. But, there are fewer choices of sizes and
sealing/shielding available.

If you can't easily make a size-for-size swap, specifying deep groove
bearings with a larger than normal internal clearance will give you
some additional thrust capacity.

That is not the case.
Radial internal clearance is for accommodating tighter fits on either
the housing and/or the shaft the bearings will be mounted in/on.
More clearance is not the solution.
If anything more clearance will lead to the balls in the bearing being
able to ride higher in the raceway and get onto the shoulder of the
raceway...this will induce skuffing and skidding and will cause a
premature failure.

The internal clearance is specified
independently of ABEC class, usually with a C plus a number. There is
no consistent nomenclature between mfrs, so speak to a supplier you
trust or directly to the mfr's tech support before concluding that one
mfr's C3 is looser than another's C0. SKF has always been helpful when
I've had a question.

Larger internal clearance in a deep groove bearing allows the balls to
ride higher on the race's walls. This will put the contact points
between the balls and races more in line with an axial load, which is
what an angular contact bearing is designed to do.

Don't expect a ball bearing to be able to do what an angular contact
bearing can do. while ball bearings may be able to handle a certain
amount of thrust the more clearance just allows the ball to get out of
the load zone and into areas where there will be problems.

"Joe AutoDrill" posted
in rec.crafts.metalworking on Fri,
27 Feb 2009 10:45:02 -0500:

One of our customers with a special three spindle drilling head is having
some problems. They went out and bought a drill press that can not get the
RPM / thrust settings right for a particular drilling process they need to
run.

Rather than buy a new drill press, they bought some tooling that can handle
the higher feed rate per revolution.

The head is being used to drill 2 holes at 0.326" diameter and one hole at
0.218" diameter. The material is stainless steel and their machine makes a
lot of thrust. They can not reduce the thrust or increase the RPM unless
they buy a new drill press and of course, they are resisting that idea
because the drill press they would need to buy (probably a used Bridgeport
actually) costs much more than the head I sold them.

The bearings inside the head do not last very long because they are being
pushed way past their thrust ratings. Because of the close C-C spacing,
there are no larger bearings or "stacked" bearing options available to me at
this time without actually building them a brand new drilling head. They
are open to this as the fault here is clear - they need the proper machine
to drive the head...

But... Before we go down either the new and more robust head route or new
machine to drive the head route... I'm wondering if there are any bearing
experts out here who can tell me whether there are any specialty bearings
that take higher thrust numbers or even vibration better than a typical ABEC
1 bearing. I was thinking ceramic, but I don't think they would take
vibration very well... We were thinking of going to higher ABEC numbers on
the bearings but I'm not sure that will help either s it shows higher RPM
ratings, but not much difference in thrust ratings.

Before anyone asks, we can't change the input/output RPM of the head to
compensate either. If I could simply have the inpututput at 1:2, that
would solve it, but there is no room for the gearing inside their footprint
to do that...

Random thoughts from the wild welcomed! We have two solutions as noted
above, but the customer would like to avoid both if possible...

#1 - Grease change - Use a grease that has extra pressure additives.
This will help your bearings survive the incipient thrust loads by
keeping the boundary layer intact.

#2 - Cheap and easy way...wave washers. Old trick used by electric
motor manufactures to solve thrust loads without going to an angular
contact bearing. You might have to experiment....and it depends on how
high your loads are if this will work.

If I knew what size bearings you are using I could offer more help.
If you know what the loads are (radial and axial) and speed I can run
some life calculations and give you an *expected* life.
Since I have no real idea how your application is set up and what type
of fits you are using in your housing and shaft I can only offer
*general* suggestions.

and yes...I am a bearing engineer.

The other alternative is to go to an Angular contact or if there is
enough room try using matched sets of ball bearings or even a small
tapered roller bearing.

#1 - Grease change - Use a grease that has extra pressure additives.
This will help your bearings survive the incipient thrust loads by
keeping the boundary layer intact.

We are using a Du Pont Teflon Severe Service Grease now - Part DGS616101 if
it matters. Not sure there is much out there better unless you go exotic.

#2 - Cheap and easy way...wave washers. Old trick used by electric
motor manufactures to solve thrust loads without going to an angular
contact bearing. You might have to experiment....and it depends on how
high your loads are if this will work.

My thoughts exactly... Until they sent them back to me flattened and broken
into pieces. I *really* wish I could go to their site and see the
application first hand, but in 10 years, we've made less than a half dozen
trips to customers because we have very few problems... Hopefully, this
won't be the exception long-term. We tried stacking multiples with the same
results and more will only increase linear "float" which causes chatter and
then more bad stuff.

If I knew what size bearings you are using I could offer more help.
If you know what the loads are (radial and axial) and speed I can run
some life calculations and give you an *expected* life.
Since I have no real idea how your application is set up and what type
of fits you are using in your housing and shaft I can only offer
*general* suggestions.

Wish I could tell you! It's a super-secret. G

and yes...I am a bearing engineer.

Maybe via private e-mail then... But not just yet. Still looking for a
simple solution.

The other alternative is to go to an Angular contact or if there is
enough room try using matched sets of ball bearings or even a small
tapered roller bearing.

Unfortunately, no room. It's pushed to the minimum limits now. Imagine
trying to get two chucks 0.875" away from each other and drilling 0.326"
holes... Same rotation. That's what I'm dealing with here. Intermediate
gear and bearings and all...
--


Regards,
Joe Agro, Jr.
(800) 871-5022
01.908.542.0244
Automatic / Pneumatic Drills: http://www.AutoDrill.com
Multiple Spindle Drills: http://www.Multi-Drill.com
Flagship Site: http://www.Drill-N-Tap.com

V8013-R

Joe AutoDrill wrote:

I'm a bit confused about where the problem lies. What is controlling the
thrust? The drill press is supplying the rotation power and spindle, but
what is driving the spindle or heads travel / thrust? It would seem that
it would be separately controllable. Is it a travel per revolution
thing, and if so can you rework the drive ratio to that?

Gear head drill press. The RPM that the drills need to run at (maximum) is
too slow for the lowest feed rate the machine offers. They can't lower the
feed rate and can't speed up the RPM so they play with funny tooling to make
it work... but then the extra feed rate at the slow RPM causes a tremendous
load on the drilling head.

I'm waiting for photos / bad parts to know exactly what it is doing to the
bearings...

Ah, then the air cylinder retrofit sounds like the way to go. Constant
force vs. travel per revolution.

On Fri, 27 Feb 2009 22:15:31 -0500, Ned Simmons
wrote:


snip

Axial loads != thrust loads.

Huh?? Can you explain the distinction, please?

Should have wrote radial load...
Ok...go to imaginary land......

Below is a bearing
__
| | |
| | | radial or axial load
| | |
|_| |
V
Thrust load---------

The bearing is designed to carry a load at a right angle to the
rotation of the bearing (radial/axial load).

Where are you getting this? Radial and axial load *are not* the same
thing; thrust and axial load *are* the same.

You are big on web pages.

Try this:

http://science.howstuffworks.com/bearing2.htm


snip

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

Regarding the effect of clearance on thrust carrying capability,
Fafnir says, "Internal clearance is sometimes utilized to compensate
for thermal expansion of bearings, shafts, and housings or to provide
a contact angle in the bearing after mounting."

The guys is having *extreme* thrust loads.
The thrust loads are causing the bearing to fail.
Using a single row ball bearing to accommodate any significant thrust
loads that displace the inner and outer rings in relation to each
other more than half the amount of specified internal clearance is not
good practice.

Similarly, Barden says, "Proper internal clearance will provide a
suitable contact angle to support thrust loads or to meet exacting
requirements on elastic yield."

Ya know...I could get into hoop strength, compression loads in the
load zone, etc. etc. and it has nothing to do with the problem cited.
The bearings are failing due to the simple fact that they cannot
accommodate the thrust loads involved in the application.

But...you have to be right...and I am wrong.
I would suggest you read a very informative book by Tedric Harris.

You won...have fun with the last word too...be creative with it.




--
K. A. Cannon
kevin.a.cannon at gmail.com.

COOSN-266-06-02374
Hammer of Thor, April 2005
PIERRE SALINGER MEMORIAL HOOK, LINE & SINKER June 2007
Barbara Woodhouse Memorial Dog Whistle X 2
#9 People ruining UseNet lits.
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http://www.themonastery.org/dev/cert...10010810040414

In article ,
Ecnerwal wrote:

In article ,
"Joe AutoDrill" wrote:

Random thoughts from the wild welcomed! We have two solutions as noted
above, but the customer would like to avoid both if possible...

Well, I don't claim to be an expert, but I am a throwback at various
times, and sometimes being a throwback is a good thing.

Without a picture/drawing to work from, I'm sort of flailing in the dark
here a bit, but it sounds like you are using ball bearings, and probably
depending on them for taking the thrust load sideways.

And you say you don't have space, so doing something like putting in a
dedicated roller thrust bearing is out, and using tapered roller
bearings is out.

But you might be able to use plain bronze, or Oilite. Plain bronze takes
higher loads. You're at low speed, high thrust, which is a good realm
for bronze. It might mean having to actually oil things, but plain
bearings do take considerable loads better than point contact bearings...

Again, flailing in the dark, you'll probably have to custom machine such
bearings to take both loads in the limited space available, but that
should be possible, I think.

I was also thinking of plain bearings, but I would add a twist: Poured
babbit bearings. Machine a stout integral flange into the shaft, pour
babbit around it with steel shim dams so it can be pulled apart and oil
grooves machined into the bearing surfaces.

Joe Gwinn

How did you do it? Internal gears? stacked? Magic? How are the
drills retained? 00 Morse taper?

Hardened, helical internal gears and ER-style spindles. ER16M
--


Regards,
Joe Agro, Jr.
(800) 871-5022
01.908.542.0244
Automatic / Pneumatic Drills: http://www.AutoDrill.com
Multiple Spindle Drills: http://www.Multi-Drill.com
Flagship Site: http://www.Drill-N-Tap.com

V8013-R

On Mon, 2 Mar 2009 08:34:42 -0500, "Joe AutoDrill"
wrote:

How did you do it? Internal gears? stacked? Magic? How are the
drills retained? 00 Morse taper?

Hardened, helical internal gears and ER-style spindles. ER16M
-------------
Sounds like a quality unit.

Without knowing the design parameters such as the helix and
pressure angle it is hard to estimate, but helical gears generate
axial as well as radial thrust in operation, which increases as
the load increases.

Is the helix angle of your gears such that it bucks or reinforces
the thrust required for the drill to penetrate?

Also second another posters idea that it may be possible to put a
thrust bearing on top of the drive gear to absorb some of the
load. Impregnated bronze [teflon?] may be adequate.


Unka' George [George McDuffee]
-------------------------------------------
He that will not apply new remedies,
must expect new evils:
for Time is the greatest innovator: and
if Time, of course, alter things to the worse,
and wisdom and counsel shall not alter them to the better,
what shall be the end?

Francis Bacon (1561-1626), English philosopher, essayist, statesman.
Essays, "Of Innovations" (1597-1625).

Hardened, helical internal gears and ER-style spindles. ER16M
-------------
Sounds like a quality unit.

Most customers think so. grin

This is the first problem unit I've had in 6 years that the cause wasn't
readily available... Until today that is...

Customer just told me another interesting tibdit... They are breaking
drills (twisting them apart in the bushing) so there is definitly a set-up
problem on their end... We shall see!

Regards,
Joe Agro, Jr.
(800) 871-5022
01.908.542.0244
Automatic / Pneumatic Drills: http://www.AutoDrill.com
Multiple Spindle Drills: http://www.Multi-Drill.com
Flagship Site: http://www.Drill-N-Tap.com

V8013-R

On Mon, 2 Mar 2009 15:49:58 -0500, "Joe AutoDrill"
wrote:

Hardened, helical internal gears and ER-style spindles. ER16M
-------------
Sounds like a quality unit.

Most customers think so. grin

This is the first problem unit I've had in 6 years that the cause wasn't
readily available... Until today that is...

Customer just told me another interesting tibdit... They are breaking
drills (twisting them apart in the bushing) so there is definitly a set-up
problem on their end... We shall see!

Side loading? Sticking? Too aggressive a feed rate? Interrupted
cut from hitting the void of a crossdrill port? Or breaking through
an angled inner surface? Wrong sharpening angle and they are
grabbing? Working dry?

Buying their drill bits from the Peoples' Noodle Factory and Steel
Works to save a few pennies?

I'm sure you can list some even more esoteric reasons...

Try analyzing their materials, then send them a fresh head with a
dozen matching good bits (and reccomended feeds/speeds chart), and a
quart of your favorite cutting oil, and have them try it again. And if
it's an interrupted cut at any point, go slow and easy till past it.

If it all of a sudden goes smooth as butter... ;-)

-- Bruce --

Side loading? Sticking? Too aggressive a feed rate? Interrupted
cut from hitting the void of a crossdrill port? Or breaking through
an angled inner surface? Wrong sharpening angle and they are
grabbing? Working dry?

....Only thing I can 100% guarantee they are not doing is working dry. In
stainless, that would result in an immediate loss of tooling.
--


Regards,
Joe Agro, Jr.
(800) 871-5022
01.908.542.0244
Automatic / Pneumatic Drills: http://www.AutoDrill.com
Multiple Spindle Drills: http://www.Multi-Drill.com
Flagship Site: http://www.Drill-N-Tap.com

V8013-R

On Mar 3, 8:24*am, "Joe AutoDrill" wrote:
...Only thing I can 100% guarantee they are not doing is working dry. *In
stainless, that would result in an immediate loss of tooling.
Joe Agro, Jr.

I almost always cut dry or with a little brushed-on oil, at low speed
and manual feed. Do you have any handy rules of thumb on the limits of
dry machining?

Jim Wilkins
More time than money.

...Only thing I can 100% guarantee they are not doing is working dry. In
stainless, that would result in an immediate loss of tooling.
Joe Agro, Jr.

I almost always cut dry or with a little brushed-on oil, at low speed
and manual feed. Do you have any handy rules of thumb on the limits of
dry machining?

We are talking stainless steel here I presume?

Brushed on oil is usually enough with stainless as long as you re-apply
somewhat often or the material is not really thick. If going dry, RPM rates
have to be super-low.

Rules of thumb for me are to never drill stainless dry. I use only HSS
tools so drilling SS dry results in immediate dull tooling. Stainless
simply does not carry heat away from the source very well and overheating is
virtually instant at normal speeds.

The chart on the following page presumes coolant for stainless and is a
conservative set of numbers in most cases:

http://tinyurl.com/ToolSpeeds

Regards,
Joe Agro, Jr.
(800) 871-5022
01.908.542.0244
Automatic / Pneumatic Drills: http://www.AutoDrill.com
Multiple Spindle Drills: http://www.Multi-Drill.com
Flagship Site: http://www.Drill-N-Tap.com

V8013-R

"Joe AutoDrill" wrote in message
...

snip

But... Before we go down either the new and more robust head route or new
machine to drive the head route... I'm wondering if there are any bearing
experts out here who can tell me whether there are any specialty bearings
that take higher thrust numbers or even vibration better than a typical
ABEC 1 bearing. I was thinking ceramic, but I don't think they would take
vibration very well...

This is a little late but I just happened to be reading some older material
I had about ceramic bearings and I thought you'd be interested in this
comment: They're relatively free of fretting and galling because of their
strength, and they can take quite a load. But their stiffness concentrates
loads and their tensile strength can be exceeded locally when they slide
against each other, which can lead to spalling. Lubrication of some kind is
crucial, it says. I remember some running dry, but my memory is vague.

Anyway, you probably know that most of them consist of ceramic balls in
steel races, so the loads on the races still have to be considered.
All-ceramic bearings are *very* expensive.

Overall, it doesn't sound like a solution for you. The most common reason
for using ceramic bearings is their ability to handle high rpm, because
they're so light and the centrifugal loads are low. (For the nit-pickers, we
should rather say that the *centripetal* loads are low. g)

--
Ed Huntress

On Mar 3, 9:15*am, "Joe AutoDrill" wrote:
...Only thing I can 100% guarantee they are not doing is working dry. In
stainless, that would result in an immediate loss of tooling.
Joe Agro, Jr.

I almost always cut dry or with a little brushed-on oil, at low speed
and manual feed. Do you have any handy rules of thumb on the limits of
dry machining?

We are talking stainless steel here I presume?

Brushed on oil is usually enough with stainless as long as you re-apply
somewhat often or the material is not really thick. *If going dry, RPM rates
have to be super-low.

Rules of thumb for me are to never drill stainless dry. *I use only HSS
tools so drilling SS dry results in immediate dull tooling. *Stainless
simply does not carry heat away from the source very well and overheating is
virtually instant at normal speeds.

The chart on the following page presumes coolant for stainless and is a
conservative set of numbers in most cases:

http://tinyurl.com/ToolSpeeds

Regards,
Joe Agro, Jr.

Thanks.
My only choices are 180, 350 and 600 RPM. I made a spreadsheet chart
of cutting speed for each belt position and standard tool sizes, and
try to stay around 80 FPM for steel and below 40 for stainless. So far
so good, but as you mentioned it's really slow.

Jim Wilkins