i had bought a second CNC Excello 602 for parts. My main machine needs
a tighter spindle so I took the old head apart today. I'm glad i had
an old unit to learn on, it was tuff going. I had to make up a couple
super special tools and spent more time machining than wrenching.

I learned the spindle cartidge can just be dropped out without
removing the head, big time saver on the main machine. I'd kind of
like to replace the lower bearing seal on the hi/lo gearbox but that
means removing the head so I'll likely skip this part.

When I finally got the spindle cartridge apart, little ball bearings
fell all over the floor. A couple evaporated into thin air. I guess
thay aren't good enough to re-use anyway.

I need to order bearings, the manual calls for:
2 each 7206 CTC/C78G05
1 each 7010 CTC/C78G1
1 each 7208 CTC/C78G

I can order locally and PAY. Anybody suggest a lower cost bearing
supply outlet?

Karl

"Karl Townsend" wrote in message
...
i had bought a second CNC Excello 602 for parts. My main machine needs
a tighter spindle so I took the old head apart today. I'm glad i had
an old unit to learn on, it was tuff going. I had to make up a couple
super special tools and spent more time machining than wrenching.

I learned the spindle cartidge can just be dropped out without
removing the head, big time saver on the main machine. I'd kind of
like to replace the lower bearing seal on the hi/lo gearbox but that
means removing the head so I'll likely skip this part.

When I finally got the spindle cartridge apart, little ball bearings
fell all over the floor. A couple evaporated into thin air. I guess
thay aren't good enough to re-use anyway.

I need to order bearings, the manual calls for:
2 each 7206 CTC/C78G05
1 each 7010 CTC/C78G1
1 each 7208 CTC/C78G

I can order locally and PAY. Anybody suggest a lower cost bearing
supply outlet?


Ebay.

You need a good interchange chart to double check but in all likelyhood the
first 2 on your list are simply #206 in Barden and something like 2mm9206 in
fafnir for example.

http://www.ntnamerica.com/product-su...rchange-search


The last few digits (IE the "ctc/c7xx" ) part of the bearing are generally
not important for the purposes of a spindle bearing--main thing needed being
physical size ( ID OD and thinckness ) and actual contact angle.

SEE
http://www.ebay.com/dsc/i.html?LH_Ti...arings+2mm920*

AND
http://www.kalamaprecision.com/beari...g%20manual.pdf

"PrecisionmachinisT" wrote in message
news:F4edncYvs_DDP8fSnZ2dnUVZ_vWdnZ2d@scnresearch. com...

"Karl Townsend" wrote in message
...
i had bought a second CNC Excello 602 for parts. My main machine needs
a tighter spindle so I took the old head apart today. I'm glad i had
an old unit to learn on, it was tuff going. I had to make up a couple
super special tools and spent more time machining than wrenching.

I learned the spindle cartidge can just be dropped out without
removing the head, big time saver on the main machine. I'd kind of
like to replace the lower bearing seal on the hi/lo gearbox but that
means removing the head so I'll likely skip this part.

When I finally got the spindle cartridge apart, little ball bearings
fell all over the floor. A couple evaporated into thin air. I guess
thay aren't good enough to re-use anyway.

I need to order bearings, the manual calls for:
2 each 7206 CTC/C78G05
1 each 7010 CTC/C78G1
1 each 7208 CTC/C78G

I can order locally and PAY. Anybody suggest a lower cost bearing
supply outlet?


Ebay.

You need a good interchange chart to double check but in all likelyhood
the first 2 on your list are simply #206 in Barden and something like
2mm9206 in fafnir for example.

http://www.ntnamerica.com/product-su...rchange-search


The last few digits (IE the "ctc/c7xx" ) part of the bearing are
generally not important for the purposes of a spindle bearing--main thing
needed being physical size ( ID OD and thinckness ) and actual contact
angle.

SEE
http://www.ebay.com/dsc/i.html?LH_Ti...arings+2mm920*

AND
http://www.kalamaprecision.com/beari...g%20manual.pdf



http://www.ebay.com/itm/7206-Nachi-A...em1e5b1a cc65

A gold or silver colored box generally denotes a higher quality class 9

You need a good interchange chart to double check but in all likelyhood
the first 2 on your list are simply #206 in Barden and something like
2mm9206 in fafnir for example.

http://www.ntnamerica.com/product-su...rchange-search


The last few digits (IE the "ctc/c7xx" ) part of the bearing are
generally not important for the purposes of a spindle bearing--main thing
needed being physical size ( ID OD and thinckness ) and actual contact
angle.

Can you tell me how to measure the contact angle on my existing
bearings by chance? here's the chart i got from the above link with
the numbers off the bearing itself (SKF7206 B G)

http://www.ntnamerica.com/products/b...id=RBSRA&ctc=B

It gives me the code for contact angle not the actual number

Reason I ask, I found this in a fafnir 3M (25 degree contact angle)
http://www.ebay.com/itm/FAFNIR-3MM20...em4cfadc db80

Sounds like a really good bearing pair


Thanks for your help, I'm studying this.

Karl

On 3/9/2012 4:09 PM, Karl Townsend wrote:
i had bought a second CNC Excello 602 for parts. My main machine needs
a tighter spindle so I took the old head apart today. I'm glad i had
an old unit to learn on, it was tuff going. I had to make up a couple
super special tools and spent more time machining than wrenching.

I learned the spindle cartidge can just be dropped out without
removing the head, big time saver on the main machine. I'd kind of
like to replace the lower bearing seal on the hi/lo gearbox but that
means removing the head so I'll likely skip this part.

When I finally got the spindle cartridge apart, little ball bearings
fell all over the floor. A couple evaporated into thin air. I guess
thay aren't good enough to re-use anyway.

I need to order bearings, the manual calls for:
2 each 7206 CTC/C78G05
1 each 7010 CTC/C78G1
1 each 7208 CTC/C78G

I can order locally and PAY. Anybody suggest a lower cost bearing
supply outlet?

Karl


It has been a while since I ordered any bearings, so I don't know the
status of these companies. But look for Reid Tool Supply or W.M. Berg inc.

"Karl Townsend" wrote in message
...

You need a good interchange chart to double check but in all likelyhood
the first 2 on your list are simply #206 in Barden and something like
2mm9206 in fafnir for example.

http://www.ntnamerica.com/product-su...rchange-search


The last few digits (IE the "ctc/c7xx" ) part of the bearing are
generally not important for the purposes of a spindle bearing--main
thing
needed being physical size ( ID OD and thinckness ) and actual contact
angle.

Can you tell me how to measure the contact angle on my existing
bearings by chance? here's the chart i got from the above link with
the numbers off the bearing itself (SKF7206 B G)


Sorry no way to measure after the fact

http://www.ntnamerica.com/products/b...id=RBSRA&ctc=B

It gives me the code for contact angle not the actual number


As a practical matter, contacy angle will vary depending upon the ratio of
how much load is to be placed on the end of the spindle as compared to side
loading.

So for machine that is used mostly for drilling you want to take that in
consideration as opposed to if you are going to be millling all of the time
then you want a higher rating in the direction so your bearing set will more
closely approximate a standard ball bearing IE something like 15 degrees


Reason I ask, I found this in a fafnir 3M (25 degree contact angle)

25 or 30 degrees is about middle of the road for a milling machine although
Fadal uses a 15 deg in the lower set and 30 deg in the upper so YMMV

http://www.ebay.com/itm/FAFNIR-3MM20...em4cfadc db80

Sounds like a really good bearing pair


pinch them together in a vice with a shim on the outer race and jiggle the
inners to measure preload (if any ) if you are unable to obtain specs from
the manufacturer.

But if I my memory of Fafnir's numbering systemthat is correct that is a
matched set that's intended for duplex universal mounting which means they
can be mounted face /face or back /back and either way you will end up with
zero preload.


Thanks for your help, I'm studying this.


No prob, I'll be out for the weekend but I'll check back when I return.

"PrecisionmachinisT" wrote in message
...

"Karl Townsend" wrote in message
...

You need a good interchange chart to double check but in all likelyhood
the first 2 on your list are simply #206 in Barden and something like
2mm9206 in fafnir for example.

http://www.ntnamerica.com/product-su...rchange-search


The last few digits (IE the "ctc/c7xx" ) part of the bearing are
generally not important for the purposes of a spindle bearing--main
thing
needed being physical size ( ID OD and thinckness ) and actual contact
angle.

Can you tell me how to measure the contact angle on my existing
bearings by chance? here's the chart i got from the above link with
the numbers off the bearing itself (SKF7206 B G)


Sorry no way to measure after the fact

http://www.ntnamerica.com/products/b...id=RBSRA&ctc=B

It gives me the code for contact angle not the actual number


As a practical matter, contacy angle will vary depending upon the ratio of
how much load is to be placed on the end of the spindle as compared to
side loading.

So for machine that is used mostly for drilling you want to take that in
consideration as opposed to if you are going to be millling all of the
time then you want a higher rating in the direction so your bearing set
will more closely approximate a standard ball bearing IE something like 15
degrees


Reason I ask, I found this in a fafnir 3M (25 degree contact angle)

25 or 30 degrees is about middle of the road for a milling machine
although Fadal uses a 15 deg in the lower set and 30 deg in the upper so
YMMV

http://www.ebay.com/itm/FAFNIR-3MM20...em4cfadc db80

Sounds like a really good bearing pair


pinch them together in a vice with a shim on the outer race and jiggle the
inners to measure preload (if any ) if you are unable to obtain specs from
the manufacturer.

But if I my memory of Fafnir's numbering systemthat is correct that is a
matched set that's intended for duplex universal mounting which means
they can be mounted face /face or back /back and either way you will end
up with zero preload.


Thanks for your help, I'm studying this.


No prob, I'll be out for the weekend but I'll check back when I return.

Your typical modern milling spindle has a duplex set that has the inner
races locked into the lower housing...basically its clamped tightly onto the
spindle with a jam nut and then is fitted rigidly into the housing so that
it cannot permanently migrate up nor down by even a tiny amount unless
fairly HUGE pressures are applied.

Its clamped onto the shaft with a jamb nut which by itself would cause a
zero-preload condition...but since the assembly is then pressed up into the
spindle housing against a shoulder into a cavity that is just a *tiny bit
shallower* than the bearings' height......( only shallower by a 1/2 thou or
so, mind you ) but this is how your preload actually comes about...

The upper bearings are different, basically they are intentionally allowed
to float in the axial plane, no attachment to the housing at all other than
some way to keep them from falling clear off if they were do inclined to do
so--reason this is done is so that the shaft lenght can grow due to heating
without having it affect preload ( binding or sloppiness would occur
otherwise ) and also so that undue problems don't arise with trying to
incessantly chase tool length as the spindle warms up which can be a real
PITA especially where you are under cnc control.

Your mileage may vary but the above probably describes the vast majority of
milling spindles out there today with a fairly high degree of accuracy.

....
Your mileage may vary but the above probably describes the vast majority of
milling spindles out there today with a fairly high degree of accuracy.

Wow! You know..if you keep out of politics, you actually DO know
something. Do yourself a favor and keep on mechanics and off politics,
which you obviously dont have a clue about.

Btw..he is correct.

Gunner


PT, thanks for the great advice. I bought all the bearings on eBay,
way less than the local bearing house, and I got top of the line
stuff. You saved me money.

Gunner, I bet PT thinks you should stay off politics too. VBG

Karl

"Karl Townsend" wrote in message
...
...
Your mileage may vary but the above probably describes the vast majority
of
milling spindles out there today with a fairly high degree of accuracy.

Wow! You know..if you keep out of politics, you actually DO know
something. Do yourself a favor and keep on mechanics and off politics,
which you obviously dont have a clue about.


Do us a favor and quit breathing, ****head.

Btw..he is correct.

Gunner


PT, thanks for the great advice. I bought all the bearings on eBay,
way less than the local bearing house, and I got top of the line
stuff. You saved me money.

Gunner, I bet PT thinks you should stay off politics too. VBG

Karl

"PrecisionmachinisT" wrote in message
news:27udnTzUMPgGFMDSnZ2dnUVZ_qednZ2d@scnresearch. com...

"Karl Townsend" wrote in message
...
...
Your mileage may vary but the above probably describes the vast majority
of
milling spindles out there today with a fairly high degree of accuracy.

Wow! You know..if you keep out of politics, you actually DO know
something. Do yourself a favor and keep on mechanics and off politics,
which you obviously dont have a clue about.


Do us a favor and quit breathing, ****head.

Btw..he is correct.

Gunner


PT, thanks for the great advice. I bought all the bearings on eBay,
way less than the local bearing house, and I got top of the line
stuff. You saved me money.



Okay great....now I need to let you know that my discription above was
incomplete almost to the point of being totally wrong.

In the case of the above face /face installation, IF a UNIVERSAL set is used
then you would also need to place a thin shim in between the pair of inner
races--only THEN can you add preload by setting them into a shallower cavity
in the quill cartidge or housing...alternatively, with a back-back set, you
would add a shim between the outer races instead...

In practice, there is usually a inner and an outer steel spacer thats placed
in between the bearing sets and they range in height anywheres from say
about 1/2in thick for a r8 spindle on up to about 4in thick where you have
60 taper....

At any rate, either they are the exact same height or else one of them is
say .0007 or so thinner than the other--you can surface grind these as a
set if you have a surface grinder, what you do is you take them both to a
cleanup and then you remove one of them and continue grinding the other (
which one to remove depends upon whether the actual set you are installing
is universal, back-back or face-face )...If you do this, then any set can be
used in any configuration you want as long as you check preload and properly
compensate...by clamping in a vise thus compressing the outer races in both
configurations and measuring the play (if any ) with an indicator or by
using some plastic-gage or even a piece of solder......then you can
tentatively install by setting up the stack in a manner that INTENTIONALLY
results in slop and check the situation by tapping the assembly back and
forth with dead blow oe a brass rod or similar.

Anyways, good luck...hopefully, I've provided enough insight here where you
can sucessfully finish the job if you think things through carefully as you
go along...

--if you have any other questions I'll try and help if I can but since every
bearing manufacturer seems to have their own numbering system then the
research and cross refrencing is going to have to be be up to you because I
simply don't have very much free time these days.

On Mon, 12 Mar 2012 12:29:28 -0700, "PrecisionmachinisT"
wrote:


Okay great....now I need to let you know that my discription above was
incomplete almost to the point of being totally wrong.

In the case of the above face /face installation, IF a UNIVERSAL set is used
then you would also need to place a thin shim in between the pair of inner
races--only THEN can you add preload by setting them into a shallower cavity
in the quill cartidge or housing...alternatively, with a back-back set, you
would add a shim between the outer races instead...

Precision angular contact bearing pairs almost always come with a
predetermined preload, controlled by grinding an offset in the mating
faces of the races. Flush ground bearings are available, but they're
the exception for the type of bearing we're talking about here.


In practice, there is usually a inner and an outer steel spacer thats placed
in between the bearing sets and they range in height anywheres from say
about 1/2in thick for a r8 spindle on up to about 4in thick where you have
60 taper....

At any rate, either they are the exact same height or else one of them is
say .0007 or so thinner than the other--you can surface grind these as a
set if you have a surface grinder, what you do is you take them both to a
cleanup and then you remove one of them and continue grinding the other (
which one to remove depends upon whether the actual set you are installing
is universal, back-back or face-face )

I'd be very cautious about doing this without knowing the specifics of
the bearings and spindle. As I said in above, in the great majority of
cases the bearings are ground as a set to the desired preload. The
spacers are identical in length.

--
Ned Simmons

"Ned Simmons" wrote in message ...
On Mon, 12 Mar 2012 12:29:28 -0700, "PrecisionmachinisT"
wrote:


Okay great....now I need to let you know that my discription above was
incomplete almost to the point of being totally wrong.

In the case of the above face /face installation, IF a UNIVERSAL set is used
then you would also need to place a thin shim in between the pair of inner
races--only THEN can you add preload by setting them into a shallower cavity
in the quill cartidge or housing...alternatively, with a back-back set, you
would add a shim between the outer races instead...

Precision angular contact bearing pairs almost always come with a
predetermined preload, controlled by grinding an offset in the mating
faces of the races. Flush ground bearings are available, but they're
the exception for the type of bearing we're talking about here.


In practice, there is usually a inner and an outer steel spacer thats placed
in between the bearing sets and they range in height anywheres from say
about 1/2in thick for a r8 spindle on up to about 4in thick where you have
60 taper....

At any rate, either they are the exact same height or else one of them is
say .0007 or so thinner than the other--you can surface grind these as a
set if you have a surface grinder, what you do is you take them both to a
cleanup and then you remove one of them and continue grinding the other (
which one to remove depends upon whether the actual set you are installing
is universal, back-back or face-face )

I'd be very cautious about doing this without knowing the specifics of
the bearings and spindle. As I said in above, in the great majority of
cases the bearings are ground as a set to the desired preload. The
spacers are identical in length.


Yes "most" common these days are duplex universal and they are intended for face-face mounting.

Emphasis on "most".

"PrecisionmachinisT" wrote in message news:FaCdneJsu86j0sPSnZ2dnUVZ_uKdnZ2d@scnresearch. com...

"PrecisionmachinisT" wrote in message
news:27udnTzUMPgGFMDSnZ2dnUVZ_qednZ2d@scnresearch. com...

"Karl Townsend" wrote in message
...
...
Your mileage may vary but the above probably describes the vast majority
of
milling spindles out there today with a fairly high degree of accuracy.

Wow! You know..if you keep out of politics, you actually DO know
something. Do yourself a favor and keep on mechanics and off politics,
which you obviously dont have a clue about.


Do us a favor and quit breathing, ****head.

Btw..he is correct.

Gunner


PT, thanks for the great advice. I bought all the bearings on eBay,
way less than the local bearing house, and I got top of the line
stuff. You saved me money.



Okay great....now I need to let you know that my discription above was
incomplete almost to the point of being totally wrong.

In the case of the above face /face installation, IF a UNIVERSAL set is used
then you would also need to place a thin shim in between the pair of inner
races--only THEN can you add preload by setting them into a shallower cavity
in the quill cartidge or housing...alternatively, with a back-back set, you
would add a shim between the outer races instead...

In practice, there is usually a inner and an outer steel spacer thats placed
in between the bearing sets and they range in height anywheres from say
about 1/2in thick for a r8 spindle on up to about 4in thick where you have
60 taper....

At any rate, either they are the exact same height or else one of them is
say .0007 or so thinner than the other--you can surface grind these as a
set if you have a surface grinder, what you do is you take them both to a
cleanup and then you remove one of them and continue grinding the other (
which one to remove depends upon whether the actual set you are installing
is universal, back-back or face-face )...If you do this, then any set can be
used in any configuration you want as long as you check preload and properly
compensate...by clamping in a vise thus compressing the outer races in both
configurations and measuring the play (if any ) with an indicator or by
using some plastic-gage or even a piece of solder......then you can
tentatively install by setting up the stack in a manner that INTENTIONALLY
results in slop and check the situation by tapping the assembly back and
forth with dead blow oe a brass rod or similar.

Anyways, good luck...hopefully, I've provided enough insight here where you
can sucessfully finish the job if you think things through carefully as you
go along...

--if you have any other questions I'll try and help if I can but since every
bearing manufacturer seems to have their own numbering system then the
research and cross refrencing is going to have to be be up to you because I
simply don't have very much free time these days.


This one is a pretty good book

http://www.ebay.com/sch/i.html?_from...All-Categories

My copy is the 6th edition but as I understand it New Departure basically was the company that pioneered angular contact bearing technology and so it covers the basics fairly well starting from an era in time back before flush grinding was the norm and so it was absolutely imperative that proper measurements, shimming etc were undertaken.

--definately handy to possess an understanding of this stuff should you ever find yourself in a situation where you've obtained bearings of unknown lineage or where you've got no idea how old a spindle unit is or how the preset was accomplished at time of last bearing change because otherwise, if you just toss them in there then there's a significant possibility they will fail in a fairly short period of time.

On Mon, 12 Mar 2012 18:09:21 -0700, "PrecisionmachinisT"
wrote:



This one is a pretty good book

http://www.ebay.com/sch/i.html?_from...All-Categories

My copy is the 6th edition but as I understand it New Departure basically was the company that pioneered angular contact bearing technology and so it covers the basics fairly well starting from an era in time back before flush grinding was the norm and so it was absolutely imperative that proper measurements, shimming etc were undertaken.

--definately handy to possess an understanding of this stuff should you ever find yourself in a situation where you've obtained bearings of unknown lineage or where you've got no idea how old a spindle unit is or how the preset was accomplished at time of last bearing change because otherwise, if you just toss them in there then there's a significant possibility they will fail in a fairly short period of time.

Second that. Lots of practical information on ball bearings. My 6th
edition dates to 1947.

--
Ned Simmons

thanks a bunch. i just ordered and will READ before installing. The
mill is running now, so I can wait and do it right. FWIW, 20 years ago
i replaced bearings in a surface grinder and farked it up. Had to too
scrap it and buy another. expensive lesson.

Karl