Metalworking (rec.crafts.metalworking) Discuss various aspects of working with metal, such as machining, welding, metal joining, screwing, casting, hardening/tempering, blacksmithing/forging, spinning and hammer work, sheet metal work.

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Default lost my balls, need bearings

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

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Default lost my balls, need bearings


"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












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Default lost my balls, need bearings


"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


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Default lost my balls, need bearings


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
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Default lost my balls, need bearings


"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.




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Default lost my balls, need bearings


"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.


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Default lost my balls, need bearings

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.
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