In article ,
says...


I dont know the nomenclature for front and back..but only know them as
thrust side and the other side G and the thrust side (often plainly
marked as such) need to be on the outside of the bearing stack, and
pulled together, then the entire bearing group held tightly in the
housing. Ball screw thrust bearing (double bearing) packs have a
removable "cover" that is held in place by bolts/screws that keep the
outer races held rigidly in place.often with a very thin spacer that
contacts only the facing faces G of the outer race.

Hope that helped, not confused..and that diagram in your link..is
as you indicated


That clears it up - I've just never seen the / notation to
indicate mounting arrangement. It seems the way to think about it is
that is a representation of the shape of the races, whereas the
notation I'm used to, as shown on that KOYO page, represents the contact
angle between the ball and races.

Ned Simmons

On Sun, 04 Dec 2005 19:56:52 GMT, Gunner Asch
wrote:

On Sun, 04 Dec 2005 11:28:44 +0000, wrote:

On Sat, 3 Dec 2005 22:44:51 -0500, "Terry Keeley" tkee(no
spam)@(or mail)rogers.com wrote:

Ive not removed bearings from your particular mill..but based on most
angular contact bearings...they should be mounted like this " "

With a hand snug preload.


Are you sure that's right? That symbology is for "face to face" mounting
and everyone I've talked to have said "back to back" is the way to go.


Lots of recommendations on which way to mount the bearings but no
input on why!

As I see it, if the angular contact bearings are the only
bearings on the shaft they should fit because that gives
radial location, end thrust location and maximum resistance to
angular misalignment of the shaft. By angular misalignment I mean
the axis of the shaft shifting so that the shaft centre line
traces out a double cone with the vertices located between the
two bearings. An appropriate case for this pairing arrangement
would be automobile front wheel bearings.

If,as is common, on a Mill or a Lathe a third bearing is fitted
well separated from the angular contact pair it is THIS bearing
that provides the primary resistance to shaft angular movement.
Any residual difference between this and the shaft angle defined
by the angular contact pair results in the shaft being over
constrained and generates large interbearing forces. This means
that the angular contact bearings shoud be mounted to minimise
the angular constraint - one way of visualising this is to
realise that this is half way to the geometry of a self aligning
bearing.

I am not a bearing expert but I think this is a reasonable way of
looking at it.

Jim
When you preload bearings..then put radical thrust loads on
it..which way does the off side bearing get pushed? Into or away from
the thrust?

Hardinge spindle bearings btw..are angular contact..and are mounted
with a preload cylinder between them. In the case of many or most
ballscrew thrust bearings with single end cartridges...they are inner
race to race as the pre-load cylinder.

Early Hardinges used 3 bearings..but all later ones..after the 1940s,
only used just the two, in th at configuration.

Gunner

I think you've already covered this in a later post and your
definitions agree with mine. However as an alternative
explanation:-

- preload is applied by increasing the spacing between
the shaft mounted elements or decreasing the spacing between the
outer bearing rings.

- preload is applied by DEcreasing the spacing between
the shaft mounted elements or INcreasing the spacing between the
outer bearing rings.

Jim

In article , Gunner Asch says...

Hardinge spindle bearings btw..are angular contact..and are mounted
with a preload cylinder between them. In the case of many or most
ballscrew thrust bearings with single end cartridges...they are inner
race to race as the pre-load cylinder.

Early Hardinges used 3 bearings..but all later ones..after the 1940s,
only used just the two, in th at configuration.

I think my ESM-59 is post 40s, and it did come with three bearings.

The first two of course are the angular contact pairs and take the
radial and axial loads, the remaining one at the rear of the spindle
is floating in the bore and takes only the pure radial loads of the
end of the spindle.

Jim Schwitters was kind enough to send me a copy of hardinge's breakdown
and replacement instructions for that machine - their nomenclature
for the headstock was "Type R" for what it's worth.

Apparently the HLVHs use the two angular contact pairs with preload
cylinder - likewise the DV59s?

So apparently hardinge went through the following design changes:

From collapsing cast iron shell bearings (on the cataract lathes)
to three bearing setup (starting with the BB headstocks) and then
at some time to two bearing setups after the 40s.

It would be interesting to talk to the engineers who decided how
and when to make those changes.

Jim


--
==================================================
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==================================================

In article ,
says...

- preload is applied by increasing the spacing between
the shaft mounted elements or decreasing the spacing between the
outer bearing rings.

- preload is applied by DEcreasing the spacing between
the shaft mounted elements or INcreasing the spacing between the
outer bearing rings.

From a practical standpoing however ball bearings are run with
nearly zero clearance. What this means is that in either configuration,
the name of the game is to get a rigid setup by making the clearance
very near to zero in bb or ff (balls out, or balls in) setup.

Unlike tapered roller bearings, ball bearings don't respond well
to large amounts of true preload.

Jim


--
==================================================
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==================================================

Here's a good diagram of the different arrangemenats and their symbology:

http://www.nhbb.com/engineering/precision/preload.cfm

In article ,
says...


From collapsing cast iron shell bearings (on the cataract lathes)
to three bearing setup (starting with the BB headstocks) and then
at some time to two bearing setups after the 40s.

It would be interesting to talk to the engineers who decided how
and when to make those changes.


The change from 3 bearings to two seems consistent with
Hardinge KISS philosophy. By removing redundant constraints
the 2 bearing design makes it easier to build a very true
spindle at the expense of a bit of stiffness.

Ned Simmons

In article ,
"Terry Keeley" tkee(no spam)@(or mail)rogers.com says...
Here's a good diagram of the different arrangemenats and their symbology:

http://www.nhbb.com/engineering/precision/preload.cfm


Except the OD marking on the figures on the right is
backwards from Gunner's convention. To my way of thinking
that OD marking is more consistent with the typical
representation of angular contact bearings in the middle
figures.

Ned Simmons

On Sun, 4 Dec 2005 18:00:03 -0500, "Terry Keeley" tkee(no spam)@(or
mail)rogers.com wrote:

The inner races are clamped together with a locknut, is that the proper
condition for back to back mounting?







Yes, that would call for back to back mounting as illustrated in the link in
Ned's post.



regards
mark rand
rtfm

In article , Ned Simmons
says...

It would be interesting to talk to the engineers who decided how
and when to make those changes.


The change from 3 bearings to two seems consistent with
Hardinge KISS philosophy. By removing redundant constraints
the 2 bearing design makes it easier to build a very true
spindle at the expense of a bit of stiffness.

It's not clear that the two bearing spindle is less stiff.

In the three bearing one, the last bearing runs true radial, and
its outer races *must* be free to float inside the bore of the
headstock. All the thrust loads are taken by the front duplex
pair.

I suspect the main issue that lead them to three bearings was the
differential thermal contraction rates between the cast iron
headstock and the steel spindle. In principle the three bearing
one does not suffer from any change in preload if the casting
expands more than the spindle.

The other issue is there's no real precision item inside a
three bearing headstock. The preload on the duplex pair is
set in the bearing factory, and once installed will be developed
correctly as long as all the races are up tight against each other.

In the HLVH though (for example) the preload depends critically
on the separation between the bottoms of the bearing recesses in
the casting, and the length of the 'preload cylinder' which is
nothing more than a precision spacer that separates the two
inner races. Maybe the engineers realized that the differential
thermal expansion wasn't that much of a killer, and they could
hire guys who liked cats and give 'em lots of Mt. Dew so they
could do the tricky job of assembling the bearing stack through
the headstock on the machines.

Because the spindle is constrained axially and radially by two
bearings almost a foot apart that probably does make for a fair
degree of rigidity. As opposed to having the backside only
constrained by a radial bearing floating axially in a bore.

Jim


--
==================================================
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==================================================

On 5 Dec 2005 05:17:16 -0800, jim rozen
wrote:

In article , Gunner Asch says...

Hardinge spindle bearings btw..are angular contact..and are mounted
with a preload cylinder between them. In the case of many or most
ballscrew thrust bearings with single end cartridges...they are inner
race to race as the pre-load cylinder.

Early Hardinges used 3 bearings..but all later ones..after the 1940s,
only used just the two, in th at configuration.

I think my ESM-59 is post 40s, and it did come with three bearings.

The first two of course are the angular contact pairs and take the
radial and axial loads, the remaining one at the rear of the spindle
is floating in the bore and takes only the pure radial loads of the
end of the spindle.

Jim Schwitters was kind enough to send me a copy of hardinge's breakdown
and replacement instructions for that machine - their nomenclature
for the headstock was "Type R" for what it's worth.

Apparently the HLVHs use the two angular contact pairs with preload
cylinder - likewise the DV59s?

And the HC (chuckers), TFB (later ones..mine is an early 3 bearing
machine), AHCs, DSM-A, CHNC etc etc

So apparently hardinge went through the following design changes:

From collapsing cast iron shell bearings (on the cataract lathes)
to three bearing setup (starting with the BB headstocks) and then
at some time to two bearing setups after the 40s.

It would be interesting to talk to the engineers who decided how
and when to make those changes.

Jim

And most importantly..why those changes were made.

Indeed. All likely to be dead by now..sigh

Gunner

"Pax Americana is a philosophy. Hardly an empire.
Making sure other people play nice and dont kill each other (and us)
off in job lots is hardly empire building, particularly when you give
them self determination under "play nice" rules.

Think of it as having your older brother knock the **** out of you
for torturing the cat." Gunner

On Mon, 5 Dec 2005 09:19:49 -0500, "Terry Keeley" tkee(no spam)@(or
mail)rogers.com wrote:

Here's a good diagram of the different arrangemenats and their symbology:

http://www.nhbb.com/engineering/precision/preload.cfm


Way cool. Thanks for the link.

The OmniTurn CNC lathes use a spindle cartridge, with spring preload
...there are 8 springs pressing on a plate that presses against the
back angular contact bearing. They too..are in the configuration,
with a cylinder between them.

Im going to have to swap out a cartridge later this week. I tried to
rebuild one from this particular customer several years ago...

The later Omnis use a low pressure air line to provide positive
pressure on the spindle cartridge, to assist in keeping the coolant
out of the spindle bearings. This particular shop is right next to the
Pacific ocean..and until they finally listened to me...after years of
****ing and moaning on my part..installed a high performance dryer at
their air compressors..had a water issue with their air. To the point
of the operators would regularly use their air guns to stage water
fights in the shop.

When I pulled the cartridge and opened it up..it was a solid mass of
rust. I have photos if anyone wants to see what water does to a $5000
spindle cartridge over a period of years....

So this one..which has had very very wet spindle purge air applied to
it for years....Im simply going to exchange the cartridge...and let
the rebuilder deal with it. Its gotta be grim inside....

Im also scheduled to do a spindle bearing replacement on a DV-59
tommorow. Hummm Ill ask the company if I can document the process with
photos and post em for yall. They are a aerospace fastener
company..so may be a bit..reticent. It would be nice to go along with
that FAQ I wrote a few years agon on the process.

The DV-59 will be nearly identical in process as the HC chuckers, etc
etc.

Gunner

"Pax Americana is a philosophy. Hardly an empire.
Making sure other people play nice and dont kill each other (and us)
off in job lots is hardly empire building, particularly when you give
them self determination under "play nice" rules.

Think of it as having your older brother knock the **** out of you
for torturing the cat." Gunner

On Fri, 2 Dec 2005 08:51:03 -0500, "Terry Keeley" tkee(no spam)@(or
mail)rogers.com wrote:

FWIW, the replacement bearings I ordered from Clausing a few years ago are
Fafnir 7205WN SU.


Just curious, are those angular contact bearings? I can't find those
numbers in the catalogue. The Fafnir numbers I'm getting are more like
2MM205WICRDUL, that's for a 25deg. Class 7 bearing.

Yes - 7000 series are angular contact

I dont know the nomenclature for front and back..but only know them as
thrust side and the other side G and the thrust side (often plainly
marked as such) need to be on the outside of the bearing stack, and
pulled together, then the entire bearing group held tightly in the
housing. Ball screw thrust bearing (double bearing) packs have a
removable "cover" that is held in place by bolts/screws that keep the
outer races held rigidly in place.often with a very thin spacer that
contacts only the facing faces G of the outer race.


A simple way to identify face and back is to think of the bearing as a
baseball cap. Look at the Koyo site posted earlier (
http://www.koyousa.com/KoyoCatalog/C...&c=020-020-010 )
and consider the ball to be a head and the outer race to be a baseball
cap. In this case, it appears that the bill of the baseball caps are
facing away from each other and the "back" of the heads are together.
This would be back to back mounting.

Thanks, I'll give him a try. I'm finding quite a variation in price for
essentially the same bearings. The SKF bearings were quoted at $265 by
Motion in Buffalo (or C$293 from Canadian Bearings here in Toronto) but the
Bardens are around $320 or an incredible C$512 here. Must be using our old
exchange rate of 60%!

Be careful that you buy only from an authorized distributor regardless
of which brand you choose. There are bargains out there from "gray
market" outfits but the manufacturers will not honor any warranty or
provide any service.

Ned Simmons wrote:
In article ,
"Terry Keeley" tkee(no spam)@(or mail)rogers.com says...

Here's a good diagram of the different arrangemenats and their symbology:

http://www.nhbb.com/engineering/precision/preload.cfm



Except the OD marking on the figures on the right is
backwards from Gunner's convention. To my way of thinking
that OD marking is more consistent with the typical
representation of angular contact bearings in the middle
figures.

Ned Simmons


some bearings just use a dot or circle to mark the alignment points. It
depends on the manufacturer.

John

"Terry Keeley" tkee(no spam)@(or mail)rogers.com wrote in message
.. .
Here's a good diagram of the different arrangemenats and their symbology:

http://www.nhbb.com/engineering/precision/preload.cfm


Can anyone describe which face is the "" and which is the ""?

The Fafnir 7205WN SU bearings that Clausing sold me don't have any circles,
dots, or "" marks that I can see. I'm guessing that the marked edge is the
face - would that make sense?

I suspect that my 8520 still has the original bearings, so it may be
possible to check that way, but it would be better to know this ahead of
time.

Mike

PS: Terry - this has been a great thread!

I tried to find a good .html picture for you but couldn't. If you go here
to the Barden site and look at page 13 of their "Machine Tool Catalogue"
you'll see a very good diagram of the different arrangements:

http://www.bardenbearings.com/literatr.htm

Look closely at the diagrams and you'll see the bearings have an open side
on the outer race, your bearings should have this too. In back to back the
open sides face out.

Also found info that says "The DB arrangement requires the inner rings to be
clamped whereas the DF arrangement requires the outer rings to be clamped".
It's on the NTN site here at the bottom of the page:

http://www.ntnamerica.com/Knowledge/Product_FAQs.htm

With the 8520 the lock nut bears down on the inner rings so "back to back"
should be right.

After sifting through the Yahoo posts and getting more confusion from reps
at the manufacturers I figured it would make a good topic here, thanks!

BTW I went with a pair of Barden 205HCDUL which are 15 degree contact,
duplex mounting with a light pre-load

More pix of my restoration here, getting ready to paint soon...

http://gallery.intlwaters.com/thumbn...bum=323&page=1


"Mike Henry" wrote in message
...

"Terry Keeley" tkee(no spam)@(or mail)rogers.com wrote in message
.. .
Here's a good diagram of the different arrangemenats and their
symbology:

http://www.nhbb.com/engineering/precision/preload.cfm


Can anyone describe which face is the "" and which is the ""?

The Fafnir 7205WN SU bearings that Clausing sold me don't have any
circles,
dots, or "" marks that I can see. I'm guessing that the marked edge is
the
face - would that make sense?

I suspect that my 8520 still has the original bearings, so it may be
possible to check that way, but it would be better to know this ahead of
time.

Mike

PS: Terry - this has been a great thread!

In article , says...
In article , Ned Simmons
says...

It would be interesting to talk to the engineers who decided how
and when to make those changes.


The change from 3 bearings to two seems consistent with
Hardinge KISS philosophy. By removing redundant constraints
the 2 bearing design makes it easier to build a very true
spindle at the expense of a bit of stiffness.

It's not clear that the two bearing spindle is less stiff.

In the three bearing one, the last bearing runs true radial, and
its outer races *must* be free to float inside the bore of the
headstock. All the thrust loads are taken by the front duplex
pair.

An overhung load applied at the spindle nose creates a moment that needs
to be balanced by the spindle assembly. In the two bearing spindle that
moment is resisted by the widely spaced bearings, causing the spindle to
bend between the bearings.

With the three bearing spindle, the angular contact pair at the nose not
only provides radial and axial support, but also resists the moment that
results from the overhung load. In addition, with 2 bearings at the
nose, the total radial stiffness of the bearings themselves is greater
close to the load. Clearly, since there is some angular deflection of
the spindle as it passes thru the bearing pair, there's also a bending
moment in the spindle between the front and rear bearings, but it's
smaller than with two bearings, and adds to the resisting moment
provided by the pair at the nose.


I suspect the main issue that lead them to three bearings was the
differential thermal contraction rates between the cast iron
headstock and the steel spindle. In principle the three bearing
one does not suffer from any change in preload if the casting
expands more than the spindle.

No doubt that's one reason that bearing arrangement is so widely used.


The other issue is there's no real precision item inside a
three bearing headstock. The preload on the duplex pair is
set in the bearing factory, and once installed will be developed
correctly as long as all the races are up tight against each other.

In the HLVH though (for example) the preload depends critically
on the separation between the bottoms of the bearing recesses in
the casting, and the length of the 'preload cylinder' which is
nothing more than a precision spacer that separates the two
inner races.

I'd expect to find there's both an inner and outer spacer, match ground,
though the outer spacer may be fixed in the spindle cartridge.

Maybe the engineers realized that the differential
thermal expansion wasn't that much of a killer, and they could
hire guys who liked cats and give 'em lots of Mt. Dew so they
could do the tricky job of assembling the bearing stack through
the headstock on the machines.

I hear those guys work cheap, too. I wonder if the 3000RPM top speed of
the HLVH is a consequence of the the bearing spacing. I often wish my
Feeler would turn faster. Likely the permanent grease lube is a limiting
factor as well.


Because the spindle is constrained axially and radially by two
bearings almost a foot apart that probably does make for a fair
degree of rigidity. As opposed to having the backside only
constrained by a radial bearing floating axially in a bore.


As long as the angular contact pair is carrying the thrust loads, the
fact that the radial bearing is floating axially has no effect on its
ability to carry a radial load. A bigger issue is the fact that a single
bearing will inevitably have some small amount of radial clearance, so
it's likely that light loads at the nose may not load the rear bearing
until its clearance is taken up. This is likely one reason it's common
to see a preloaded axially floating pair at the back end of a spindle in
place of the single bearing.

Ned Simmons

In article , Ned Simmons
says...

In the HLVH though (for example) the preload depends critically
on the separation between the bottoms of the bearing recesses in
the casting, and the length of the 'preload cylinder' which is
nothing more than a precision spacer that separates the two
inner races.

I'd expect to find there's both an inner and outer spacer, match ground,
though the outer spacer may be fixed in the spindle cartridge.

Gunner will no doubt correct me if I'm wrong, but my understanding
(based on his overhaul instructions) is that the outer races
are separated only by the headstock casting. These machines do not
have a 'cartridge' per se. The rear bearing comes out the back,
the front one comes out the front.

Maybe the engineers realized that the differential
thermal expansion wasn't that much of a killer, and they could
hire guys who liked cats and give 'em lots of Mt. Dew so they
could do the tricky job of assembling the bearing stack through
the headstock on the machines.

I hear those guys work cheap, too. I wonder if the 3000RPM top speed of
the HLVH is a consequence of the the bearing spacing. I often wish my
Feeler would turn faster. Likely the permanent grease lube is a limiting
factor as well.


Because the spindle is constrained axially and radially by two
bearings almost a foot apart that probably does make for a fair
degree of rigidity. As opposed to having the backside only
constrained by a radial bearing floating axially in a bore.


As long as the angular contact pair is carrying the thrust loads, the
fact that the radial bearing is floating axially has no effect on its
ability to carry a radial load. A bigger issue is the fact that a single
bearing will inevitably have some small amount of radial clearance, so
it's likely that light loads at the nose may not load the rear bearing
until its clearance is taken up. This is likely one reason it's common
to see a preloaded axially floating pair at the back end of a spindle in
place of the single bearing.

My real concern is that for the rear radial bearing to float, it must
have some non-zero clearance in the headstock bore. Even if small it
is present and will serve to reduce the rigidity of the *rear* of the
spindle. The BB headstock machine I overhauled had the rear bearing
fitted snugly but I was able to extract it without resorting to heroic
measures.

I am not certain but the instructions that Jim Schwitters sent me
for the more modern "R" type headstock imply that there is a sort
of preload spring for the rear bearing. I did not disassemble the
machine far enough to see that, I was only trying to verify the
state of the lube inside the three bearings.

Jim


--
==================================================
please reply to:
JRR(zero) at pkmfgvm4 (dot) vnet (dot) ibm (dot) com
==================================================

"Terry Keeley" tkee(no spam)@(or mail)rogers.com wrote in message
...
I tried to find a good .html picture for you but couldn't. If you go here
to the Barden site and look at page 13 of their "Machine Tool Catalogue"
you'll see a very good diagram of the different arrangements:

http://www.bardenbearings.com/literatr.htm

Look closely at the diagrams and you'll see the bearings have an open side
on the outer race, your bearings should have this too. In back to back
the
open sides face out.

Also found info that says "The DB arrangement requires the inner rings to
be
clamped whereas the DF arrangement requires the outer rings to be
clamped".
It's on the NTN site here at the bottom of the page:

http://www.ntnamerica.com/Knowledge/Product_FAQs.htm

With the 8520 the lock nut bears down on the inner rings so "back to back"
should be right.

Thanks - I should be able to figure it out now.

After sifting through the Yahoo posts and getting more confusion from reps
at the manufacturers I figured it would make a good topic here, thanks!

BTW I went with a pair of Barden 205HCDUL which are 15 degree contact,
duplex mounting with a light pre-load

More pix of my restoration here, getting ready to paint soon...

http://gallery.intlwaters.com/thumbn...bum=323&page=1

It's looking pretty good - when do you think you'll have it all up and
running? I've only stripped down and repainted two tools (a shaper and a
die filer) and both took me far longer than I expected. Brush painting
seems to take forever, especially with a couple of coats of primer and top
coat.



"Mike Henry" wrote in message
...

"Terry Keeley" tkee(no spam)@(or mail)rogers.com wrote in message
.. .
Here's a good diagram of the different arrangemenats and their
symbology:

http://www.nhbb.com/engineering/precision/preload.cfm


Can anyone describe which face is the "" and which is the ""?

The Fafnir 7205WN SU bearings that Clausing sold me don't have any
circles,
dots, or "" marks that I can see. I'm guessing that the marked edge is
the
face - would that make sense?

I suspect that my 8520 still has the original bearings, so it may be
possible to check that way, but it would be better to know this ahead of
time.

Mike

PS: Terry - this has been a great thread!

It's looking pretty good - when do you think you'll have it all up and
running? I've only stripped down and repainted two tools (a shaper and a
die filer) and both took me far longer than I expected. Brush painting
seems to take forever, especially with a couple of coats of primer and top
coat.

It's looing like I'll shoot 2 coats of primer tomorrow and the two topcoats
on Friday so the paint will be done (lots of masking!).

Next week I'll start re-assembly, I've got parts on the way from Clausing
and should have the bearings this Friday so hopefuly all will go well. I
really, really want to have it done for Christmas so I can make some chips
over the holidays!

In article ,
says...
In article , Ned Simmons
says...

In the HLVH though (for example) the preload depends critically
on the separation between the bottoms of the bearing recesses in
the casting, and the length of the 'preload cylinder' which is
nothing more than a precision spacer that separates the two
inner races.

I'd expect to find there's both an inner and outer spacer, match ground,
though the outer spacer may be fixed in the spindle cartridge.

Gunner will no doubt correct me if I'm wrong, but my understanding
(based on his overhaul instructions) is that the outer races
are separated only by the headstock casting. These machines do not
have a 'cartridge' per se. The rear bearing comes out the back,
the front one comes out the front.

Yeah, I just looked in the HLVH manual. I don't know how I
got it in my head that it's a cartridge spindle, unless on
account of a Rathbone chucker I once had which was a
functional copy of an HC. The Rathbone did have a
cartridge. A functional copy in that all the HC tooling and
attachments fit - it was constructed more like the Monarch
chucker with round ways.

But there is a separate spacer that appears to be pinned in
the headstock casting that separates the bearings' outer
races.


Maybe the engineers realized that the differential
thermal expansion wasn't that much of a killer, and they could
hire guys who liked cats and give 'em lots of Mt. Dew so they
could do the tricky job of assembling the bearing stack through
the headstock on the machines.

I hear those guys work cheap, too. I wonder if the 3000RPM top speed of
the HLVH is a consequence of the the bearing spacing. I often wish my
Feeler would turn faster. Likely the permanent grease lube is a limiting
factor as well.


Because the spindle is constrained axially and radially by two
bearings almost a foot apart that probably does make for a fair
degree of rigidity. As opposed to having the backside only
constrained by a radial bearing floating axially in a bore.


As long as the angular contact pair is carrying the thrust loads, the
fact that the radial bearing is floating axially has no effect on its
ability to carry a radial load. A bigger issue is the fact that a single
bearing will inevitably have some small amount of radial clearance, so
it's likely that light loads at the nose may not load the rear bearing
until its clearance is taken up. This is likely one reason it's common
to see a preloaded axially floating pair at the back end of a spindle in
place of the single bearing.

My real concern is that for the rear radial bearing to float, it must
have some non-zero clearance in the headstock bore. Even if small it
is present and will serve to reduce the rigidity of the *rear* of the
spindle. The BB headstock machine I overhauled had the rear bearing
fitted snugly but I was able to extract it without resorting to heroic
measures.

I don't disagree, but think the bearing's radial looseness
is a more likely culprit. Barden recommends a transition
fit, around .0002 either side of line to line, for the
housing in this situation. I'd describe the housing fit on
the 3rd bearing in the few spindles I've had apart as a
wringing fit - tighter than a slip fit, but moves with firm
hand pressure. In either case, movement due to radial
clearance in the bearing itself or radial movement of the
bearing in the bore, you'd expect to see a knee in a force
vs. deflection curve. I mentioned in an earlier post in
this thread that I was able to see the effect of the radial
bearing in a BP spindle by measuring the difference in
deflection at the nose with the top radial bearing both
removed and installed, but I don't recall checking for a
change in stiffness as the top bearing loads up. So I just
did a quick test with a spring scale and indicator on the
BP.

I mounted a 50 millionths indicator on an Indicol holder
clamped to the spindle collar and placed the probe on the
OD of the quill. A spring scale was clamped in the vise and
arranged to push on a rod held in a drill chuck. Cranking
the table allowed me to apply a controlled force while
monitoring deflection. I *may* have been able to see the
expected effect, but the deflections were much too small to
measure reliably - even with the force applied about 5"
below the spindle nose, a 60# load only moved the spindle
about .00015 relative to the quill. It *looked* like the
first .00005 occurred at about 10# load, but it'd take much
better resolution to be sure.

Ned Simmons

In article , Ned Simmons
says...

Gunner will no doubt correct me if I'm wrong, but my understanding
(based on his overhaul instructions) is that the outer races
are separated only by the headstock casting. These machines do not
have a 'cartridge' per se. The rear bearing comes out the back,
the front one comes out the front.

Yeah, I just looked in the HLVH manual. I don't know how I
got it in my head that it's a cartridge spindle, unless on
account of a Rathbone chucker I once had which was a
functional copy of an HC. The Rathbone did have a
cartridge. A functional copy in that all the HC tooling and
attachments fit - it was constructed more like the Monarch
chucker with round ways.

But there is a separate spacer that appears to be pinned in
the headstock casting that separates the bearings' outer
races.

Interesting, I've never seen an exploded diagram for one
of those, nor have I had one that far apart. A steel cylinder
pinned into the casting would indeed eliminate the thermal
expansion issue to a large degree, and likewise put all the
"sin" in getting the OD race separation away from the rough
headstock casting, into something that could be more tightly
controlled during manufacture. All things that hardinge could
be expected to figure out, and implement.

My real concern is that for the rear radial bearing to float, it must
have some non-zero clearance in the headstock bore. Even if small it
is present and will serve to reduce the rigidity of the *rear* of the
spindle. The BB headstock machine I overhauled had the rear bearing
fitted snugly but I was able to extract it without resorting to heroic
measures.

I don't disagree, but think the bearing's radial looseness
is a more likely culprit. Barden recommends a transition
fit, around .0002 either side of line to line, for the
housing in this situation. I'd describe the housing fit on
the 3rd bearing in the few spindles I've had apart as a
wringing fit - tighter than a slip fit, but moves with firm
hand pressure.

Yep, that's just about what I felt when I removed the spindle
from that BB headstock lathe.

In either case, movement due to radial
clearance in the bearing itself or radial movement of the
bearing in the bore, you'd expect to see a knee in a force
vs. deflection curve. I mentioned in an earlier post in
this thread that I was able to see the effect of the radial
bearing in a BP spindle by measuring the difference in
deflection at the nose with the top radial bearing both
removed and installed, but I don't recall checking for a
change in stiffness as the top bearing loads up. So I just
did a quick test with a spring scale and indicator on the
BP.

I mounted a 50 millionths indicator on an Indicol holder
clamped to the spindle collar and placed the probe on the
OD of the quill. A spring scale was clamped in the vise and
arranged to push on a rod held in a drill chuck. Cranking
the table allowed me to apply a controlled force while
monitoring deflection. I *may* have been able to see the
expected effect, but the deflections were much too small to
measure reliably - even with the force applied about 5"
below the spindle nose, a 60# load only moved the spindle
about .00015 relative to the quill. It *looked* like the
first .00005 occurred at about 10# load, but it'd take much
better resolution to be sure.

Interesting test. If I could figure out a way to take home
my federal electronic indicator, I could try that in the
hardinge. Of course, that may well have a preload spring
for the rear radial bearing, if Jim Schwitter's diagram matches
that machine.

Jim


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On 6 Dec 2005 18:37:37 -0800, jim rozen
wrote:


I'd expect to find there's both an inner and outer spacer, match ground,
though the outer spacer may be fixed in the spindle cartridge.

Gunner will no doubt correct me if I'm wrong, but my understanding
(based on his overhaul instructions) is that the outer races
are separated only by the headstock casting. These machines do not
have a 'cartridge' per se. The rear bearing comes out the back,
the front one comes out the front.


Correct

Gunner

"Pax Americana is a philosophy. Hardly an empire.
Making sure other people play nice and dont kill each other (and us)
off in job lots is hardly empire building, particularly when you give
them self determination under "play nice" rules.

Think of it as having your older brother knock the **** out of you
for torturing the cat." Gunner

On 8 Dec 2005 05:33:04 -0800, jim rozen
wrote:

In article , Ned Simmons
says...

Gunner will no doubt correct me if I'm wrong, but my understanding
(based on his overhaul instructions) is that the outer races
are separated only by the headstock casting. These machines do not
have a 'cartridge' per se. The rear bearing comes out the back,
the front one comes out the front.

Yeah, I just looked in the HLVH manual. I don't know how I
got it in my head that it's a cartridge spindle, unless on
account of a Rathbone chucker I once had which was a
functional copy of an HC. The Rathbone did have a
cartridge. A functional copy in that all the HC tooling and
attachments fit - it was constructed more like the Monarch
chucker with round ways.

But there is a separate spacer that appears to be pinned in
the headstock casting that separates the bearings' outer
races.

Interesting, I've never seen an exploded diagram for one
of those, nor have I had one that far apart. A steel cylinder
pinned into the casting would indeed eliminate the thermal
expansion issue to a large degree, and likewise put all the
"sin" in getting the OD race separation away from the rough
headstock casting, into something that could be more tightly
controlled during manufacture. All things that hardinge could
be expected to figure out, and implement.

There is indeed a cylinder inside the head, but its a hard pressfit
into the headstock casting and pinned via a steel taper pin from top
dead center of the headstock. I actually broke one free from a
headstock that had a heavily rusted in bearing. Using my 20lb bearing
knocker with a 10lb sledge sorta got it moveing...G

But IRRC..the cylinder doesnt contact the outer race. Ive still to do
that DV-59 yet...Ive had pnuemonia ..sigh and Ill check carefuly when
I yank the spindle.

Gunner


My real concern is that for the rear radial bearing to float, it must
have some non-zero clearance in the headstock bore. Even if small it
is present and will serve to reduce the rigidity of the *rear* of the
spindle. The BB headstock machine I overhauled had the rear bearing
fitted snugly but I was able to extract it without resorting to heroic
measures.

I don't disagree, but think the bearing's radial looseness
is a more likely culprit. Barden recommends a transition
fit, around .0002 either side of line to line, for the
housing in this situation. I'd describe the housing fit on
the 3rd bearing in the few spindles I've had apart as a
wringing fit - tighter than a slip fit, but moves with firm
hand pressure.

Yep, that's just about what I felt when I removed the spindle
from that BB headstock lathe.

In either case, movement due to radial
clearance in the bearing itself or radial movement of the
bearing in the bore, you'd expect to see a knee in a force
vs. deflection curve. I mentioned in an earlier post in
this thread that I was able to see the effect of the radial
bearing in a BP spindle by measuring the difference in
deflection at the nose with the top radial bearing both
removed and installed, but I don't recall checking for a
change in stiffness as the top bearing loads up. So I just
did a quick test with a spring scale and indicator on the
BP.

I mounted a 50 millionths indicator on an Indicol holder
clamped to the spindle collar and placed the probe on the
OD of the quill. A spring scale was clamped in the vise and
arranged to push on a rod held in a drill chuck. Cranking
the table allowed me to apply a controlled force while
monitoring deflection. I *may* have been able to see the
expected effect, but the deflections were much too small to
measure reliably - even with the force applied about 5"
below the spindle nose, a 60# load only moved the spindle
about .00015 relative to the quill. It *looked* like the
first .00005 occurred at about 10# load, but it'd take much
better resolution to be sure.

Interesting test. If I could figure out a way to take home
my federal electronic indicator, I could try that in the
hardinge. Of course, that may well have a preload spring
for the rear radial bearing, if Jim Schwitter's diagram matches
that machine.

Jim

"Pax Americana is a philosophy. Hardly an empire.
Making sure other people play nice and dont kill each other (and us)
off in job lots is hardly empire building, particularly when you give
them self determination under "play nice" rules.

Think of it as having your older brother knock the **** out of you
for torturing the cat." Gunner

In article , Gunner Asch says...

There is indeed a cylinder inside the head, but its a hard pressfit
into the headstock casting and pinned via a steel taper pin from top
dead center of the headstock. I actually broke one free from a
headstock that had a heavily rusted in bearing. Using my 20lb bearing
knocker with a 10lb sledge sorta got it moveing...G

It would make sense to me if it did (contact the outer races)
because that would be one way for them to eliminate the thermal
differential expansion issues.

But IRRC..the cylinder doesnt contact the outer race. Ive still to do
that DV-59 yet...Ive had pnuemonia ..sigh and Ill check carefuly when
I yank the spindle.

Pneumomia is nothing to fool with. I've noticed you were sparse
around here lately. That's the sort of thing you have to watch
for or you will end up in the hospital for a while - like ms.
Mulligan did two years ago. Hope you are on the mend.

Jim


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==================================================
please reply to:
JRR(zero) at pkmfgvm4 (dot) vnet (dot) ibm (dot) com
==================================================