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Hi Clark,
I am a little late responding to this message but better late than never.
I like your extended spindles. I have also machined a new spindle to accept 8mm watchmaker collets and it worked out very well. I use the new spindle for a different purpose and that is as a grinding spindle on a shop built tool and cutter grinder.
Several years ago I saw an EBay listing for a box full of old Unimat spindles and parts so I bought it. It was quite a find and I was able to put together several complete Unimat spindles from all the parts.
Dick

Good news. The motor mill fan cover had been compressed (presumably during shipment) such that it was binding against the fan, thus keeping the motor shaft from turning. When I went to disassemble the mill motor, I discovered the issue, set the fan cover back in place, and tested all working. Not only did I get to learn all about this tool, but it now works!!

On Mon, Feb 13, 2023 at 10:39 AM, Julius Henry Marx wrote:

So the SKF samples I installed, which I do not recall having any markings on the box, would be 'Normal'.
ie: C2

Small correction there - Normal clearance is not C2. C2 is quite a tight clearance for high precision fits, and I doubt you'd find it readily available. Normal or C3 will be fine for the job - after all, how often do the bearings simply fail, rather than being neglected, rusty, filled with swarf, or whatever?

For me or anyone else wanting to get bearings, we are having a lot of fulfilling discussions on the subject.
However, can we figure some consensus that will tell me exactly what bearing number to buy, where to realistically get them(online), and at what price $.
Thanks to all.

Hello Keith,

I?m very grateful for your outstanding explanations. There, I could find everything I wanted to know on the subject.

Best regards, Ricardo.

Hello:

On Sun, Feb 12, 2023 at 04:45 PM, Julius Henry Marx wrote:

No problem, C[E]3 is the standard all around bearing type most everyone uses.

According to the SKF handbook, and my experience, C3 is not the usual bearing everyone uses, although it is being widely offered on Ebay and similar places. Clearance are described as C2, Normal, C3, C4 and C5. For a 17 mm bore bearing such as the 6003 the clearances are:

C2? 0 - 9?μm

Normal 3 - 18?μm?

C3? 11 - 25?μm

C4? 16 - 33?μm?

C5? 25 - 45?μm

A Normal bearing has no extra markings on it. All the others are marked C3, C4 or whatever. A Normal bearing will be installed with one race being an easy fit in the housing or on the shaft, and the other a tight fit on the shaft or in the housing. Fitting the bearing then closes up the clearances. If the bearing is tight on the shaft AND in the housing a C3 bearing is used, as the clearances are closed up a bit more. In some circumstances, usually due to temperature differences, the clearances will be closed up even more and a C4 bearing will be use. I've never seen a reason for using C5 bearing, but someone somewhere must need them. Clearances are important as bearings work best with a bit of preload on them - this stops the balls skidding on the races, and causing premature wear. However, too much preload will overstress the races and cause spalling, and short bearing life.

Radial bearings are designed, as the name suggests, for radial loads. With extra clearance the bearing can take significant axial load as well, as the line of contact between the balls and races tilts, making it more of an angular contact bearing. The more the tilt, the higher the axial load that can be applied. On the U3 the bearings have an axial preload applied by the disc springs, so I would look for a C3 or C4 bearing. Until recently it was unusual to be offered much choice of clearance off the shelf. The DB/SL uses E13 magneto bearings. These are a very old specification of angular contact bearings, ideal for the job but not available sealed, and sometimes hard to find, which is probably why this type were not used in the U3. Unfortunately angular contact bearings (according to SKF) are not available in 17 mm bore and 35 mm OD, otherwise they would be good for the U3. There aren't any magneto bearings the right size for the U3. Taper roller bearings would also be very good for the job, but are not made in these smaller sizes.

I would use sealed bearings (2RS). SKF say that 50% of bearing failures are due to too little grease, too much grease, the wrong kind of grease, or dirt in the grease. Their sealed bearings are supplied with the right amount of the right kind of grease, and they claim they are greased for life. I'm willing to believe them. I would always look for a respectable make - SKF, FAG, NSK, Koyo come to mind - bought from a proper bearing supplier.

I've just looked on Ebay and I find the SKF 7003CD bearing will fit. They are described as super-precision spindle bearings - ideal you might think - but they cost about ?120 each, so you might think twice about using them. Not sealed either.

Hi,?
I have got to know at least three motor manufacturers for the Emco Compact 5, so it?s not clear to me if there are significant differences among them, regardless if they are 110-120 / 220-240VAC, 50 / 60Hz.

There are motor made by?Antriebstechnik, Bauknecht, and Flender ATB-Loher, like the one in my C5.



Although they look much the same, between them there are differences in their specs, so maybe they use different type of ball bearings.
Here some links, for better information:

Hello:

Julius,

I thank you for your comments, they have brought some valued information for my better understanding. I assume most unwanted radial play is eliminated by the usage of Belleville or Compensating type washers, regardless the U3 does not have angular contact type ball bearings.
Then I suppose that the ball bearings that I?ve got are good enough for the job.

Best regards, Ricardo

I have an Emco Compact 5 mill motor that doesn’t want to spin. It seems that the bearings inside the motor are seized as I can’t even turn the motor shaft by hand.?

Does anyone know the bearings that I need to buy? ?I’m traveling for work and haven’t had the chance to disassemble the motor. However I’d like to get the bearings ordered while I’m gone.?

Thanks in advance.?

Hello:

I don't know what the standard/default 'E' is bearing-wise so to speak.

Yes I do.? 8^D

Sorry, I referred to 'E''instead of 'C' and on top of that, did not post the properly.

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Admin: we need to be able to edit posts to get things right if we goof up. OK?
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From the page I linked to:

If a bearing has a C code, it offers extra internal clearance. C1 offers the least extra clearance, C5 offers the most extra clearance. The extra margin C3 offer is considered 'normal'. Bearings with C3 are in fact the most commonly used.

So ...
No problem, E3 is the standard all around bearing type most everyone uses.

Best,

JHM

Hello:

On 2023-02-11 17:52, Julius Henry Marx wrote:

Hello:

On Fri, Feb 10, 2023 at 07:44 PM, Andrey Malakov (gmail) wrote:

... recommend an online reseller ...

If you have a car or a motorcycle, chances are you _also_ have a
mechanic you can trust.
If not, maybe you know someone who does.

A local mechanic can probably direct you to whoever sells them
standard bearings.
Maybe it's (like in my case) either a four block walk to get to an
expensive (but knowledgeable) reseller dowtown or a 40 minute bus ride
(up an back) to a multi-brand distributor with much more reasonable
prices.

As with the coffee machine parts I sometimes need, what I have learned
is to avoid those shops who advertise "_original _[fill in here]_ for
your _[fill in here]".

You will most probably end up paying 2x as much in the case of good
quality bearings or up to 6x as much for (presumably) lesser quality
imports.

Just take your time, shop around and compare prices.
You'll manage perfectly well.

Best,

JHM


Links:
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[1] /g/Unimat/message/59238
[2] /mt/96856827/3128643
[3] /g/Unimat/post
[4] /g/Unimat/editsub/3128643
[5] /g/Unimat/unsub

Talk to Ketan who runs Arc Eurotrade I have bought machines and tools
and bearings from him but his original business and his expertise is in
bearings.

Hello:

Just look for authorised distributors. There's probably a list of such on the SKF website.

There's lots of other high end brands out there too that do equivalent products. Timken, Koyo and FAG to name but 3.

On Fri, Feb 10, 2023 at 10:44 PM, Andrey Malakov (gmail) wrote:

online reseller that can guarantee from fake?

How can anyone do that I would think that is very hard to do in today's times of "snatch it and run"

Phill