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i was looking into buying a Tormach mill , but now i will wait
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Tormach spindle bearings - assembly fault 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.........
i was looking into buying a Tormach mill , but now i will wait
Wait for what?
Phil
Originally Posted by holbieone
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.
Progress report. Greg at Tormach was very helpful, and sent me replacement bearings immediately.
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.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?
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!
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.
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.......
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
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