[keen]

My Spindle has been making a scary 'squawky' sound from time to time.

A few days ago I decided to pull out the spindle and have a look. I pushed apart the bearings assembly, marking the bearing positions on the outer races as they appeared.

The bearings are Duplex Tandem style angular contact ball. (This means two bearings the same way at the bottom, taking the cutter thrust, and two bearings the same (but other) way at the top, to adjust against and take the spindle weight.)They are marked 'DT'

To my horror I found the top bearings were in upside down!

Yes I checked this very carefully.

The bottom bearings were in correct, both outer races 'open' at the bottoms - this means tandem style and able to take cutter thrust, and able to be adjusted by the top spindle adjusting nut.

But the top bearings were also 'open' at the bottoms - so the ajustment would put the spindle weight load on the tiny land of the outer race just past the centre of the radious. No wonder the bearings were skidding!

All the balls are scuffed as if they had not always been turning properly - they are probably beyond redemption.

I tried a local supplier for replacement bearings but as I am in New Zealand -they need to be imported anyway - and are hugely expensive - about $800.00 US. So I have contacted Greg at Tormach re urgent shipment of replacement bearings.

Never a dull moment.

Not so keen.........

[holbieone]

i was looking into buying a Tormach mill , but now i will wait

[philbur]

Wait for what?

Phil

i was looking into buying a Tormach mill , but now i will wait

[keen]

Hi holbieone - Yes don't overreact.

This may be the first time there has been a spindle bearing assembly error to date. In how many? over a thousand assemblies? your odds are good really. This would be a simple human error on assembly - and difficult to check.

Both the bearings are out of sight under the dirt cover washers - so no ISO 90001 quality control system could really pick it up once assembled.

It might have been a new man/person on the spindle assembly I suppose - so he could have put several together like this - sooner or later though he must have realised his mistake (we hope) and should have admitted it...................Then all his work should have been dismantled and checked. I know this situation only too well, having managed a factory in the 90's. Not easy.

[keen]

Progress report. Greg at Tormach was very helpful, and sent me replacement bearings immediately.

[digits]

Glad they've looked after you well

Is there any quick way to check this without pulling the bearings out - can I inspect the top set by removing the seal?

[keen]

Glad they've looked after you well

Is there any quick way to check this without pulling the bearings out - can I inspect the top set by removing the seal?

Hi Digits. You could remove the top nut on top of the pulley, then the pulley, then for saftey block up the spindle, remove the main bearing adjustment nut and under it the cover washer/plate or. (This could be tricky as it is flush). Then you could see the top bearing.

I would advise against this - you would loose your bearing adjustment setting and may not set it back correctly.

If the bearings are not noisy I would leave well alone!

[digits]

Hi Digits. You could remove the top nut on top of the pulley, then the pulley, then for saftey block up the spindle, remove the main bearing adjustment nut and under it the cover washer/plate or. (This could be tricky as it is flush). Then you could see the top bearing.

I would advise against this - you would loose your bearing adjustment setting and may not set it back correctly.

If the bearings are not noisy I would leave well alone!

Cheers - I only have a spindle, so I wouldn't have to remove any pulleys or nuts, but I'm happy to leave it well alone!

[keen]

hi digits - You only have a spindle? You mean you are holding one as a spare or.....?

[digits]

hi digits - You only have a spindle? You mean you are holding one as a spare or.....?

I just bought a Tormach BT30 spindle assembly for use on my DIY machine : http://www.cnczone.com/forums/showth...145#post474145


Cheers.

[keen]

looks good. They are well made for the money. Been studying spindle bearing design lately. One comprimise with this design is that because the opposing thrust bearings are so far apart, the greater relative heat of the spindle versus the Bearing sleeve means thermal expansion makes preload very variable and temperature dependent. Higher spec spindles use a stiff cone spring to give constant preload. This would allow higher revs............hmmmm.......

[sharpshooter90]

Digits,
Does the spindle come as a complete assembly in a sleeve that bolts into the casting? I am working on a project myself and buying off the shelf seems the simplest way to go.
What is the diameter of the sleeve?
How much is the assembly?
Thanks

[digits]

Digits,
Does the spindle come as a complete assembly in a sleeve that bolts into the casting? I am working on a project myself and buying off the shelf seems the simplest way to go.
What is the diameter of the sleeve?
How much is the assembly?
Thanks

I don't want to take this thread off topic, as I already have another thread in here about the spindle cartridge : http://www.cnczone.com/forums/showth...145#post474145

but to answer your questions, yes it is all in one, dunno haven't measured it, and about $550.

[digits]

looks good. They are well made for the money. Been studying spindle bearing design lately. One comprimise with this design is that because the opposing thrust bearings are so far apart, the greater relative heat of the spindle versus the Bearing sleeve means thermal expansion makes preload very variable and temperature dependent. Higher spec spindles use a stiff cone spring to give constant preload. This would allow higher revs............hmmmm.......

Interesting - I only need about 4,000-6,000 rpm though, which should be doable, especially if I can wrap a coolant-stream heat-exchanger around the
spindle.

[keen]

Bearings arrived after only about 6 days! All back together now and running well.

[BlueFin]

Bearings arrived after only about 6 days! All back together now and running well.

Keen, what serial number is your machine? This entire thread sounds like my machine has started to sound, I got the squeeks every now and again. Tormach is trying to help me figure it out, but I am thinking bearings at this point.

[sharpshooter90]

Blue,
If you determine that the bearings are bad or were put in wrong, you might consider going to better bearings than the Chinese replacements. Chinese sealed bearings suffer from fairly high failure due to contamination during assembly. Even if the assembly process is clean, the lubricants they use are often contaminated as well. Maybe Tormach would credit you the value of the warranty bearings toward a good quality set from a local supplier.

[veteq]

6 days and the bearings are there, one human error.
and 25.000 dollar damage for the reputation fot Tormach.

think, act.

Bad talk on a forum costs money,

regards,

11 year old student.

[philbur]

Such generalisations have no value.

How many bearings are made in China per year and by how many manufacturers, how many have you checked and confirmed failure due to contamination? Maybe more to the point how many Tormach bearing assemblies have you checked for contamination failure.

How big is "fairly high" and how frequent is "often" and what's your sample size.

I think the waffle ratio on this forum is "fairly high" and the advise given is "often" suspect.

Just an alternative point of view.
Phil

Chinese sealed bearings suffer from fairly high failure due to contamination during assembly. Even if the assembly process is clean, the lubricants they use are often contaminated as well. Maybe Tormach would credit you the value of the warranty bearings toward a good quality set from a local supplier.

[jalessi]

China has world class manufacturing ability also.

Making a blanket statement suggesting all the bearings they produce are contaminated is ludicrous.

Do you think this company " http://www.nsk.com.cn/ " would stand for that type of business practice?


Jeff...