On Fri, Feb 17, 2023 at 03:21 AM, Julius Henry Marx wrote:
Just have to figure out the size of the pulleys and draw up a precision jig for the bits, probably the hardest part to make.
No, keep it much simpler - no spindle, no pulleys - just mount the wheel direct onto the motor shaft. To guide the toolbit you need a tilting table to set your basic angle. If you are going to be very fancy you can add a protractor to the table so you can set up compound angles. If you can grind a reasonable toolbit freehand with a normal bench grinder you don't need much help to grind a much better one. I found that with the slower cutting rate of a fine diamond wheel I had time to think about what I was doing and make small adjustments before it was too late. At the same time I got ground surfaces that were almost polished, and very sharp cutting edges, and it still didn't take long.
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On Thu, Feb 16, 2023 at 11:01 PM, Keith S. Angus wrote:
... with a smallish (50 - 100 mm) diamond grinding wheel ...
Yes, that was more or less what I was thinking of. It is the type of grinding wheel that would allow a precise geometry on the faces of a tool made from 4mm/8mm sq. HSS stock.
... you could sell it ...
I don't see me making much profit vis-a-vis keeping it and getting another. And in spite of its limitations, it is a reasonably well built 2 speed motor that has been working perfectly well for the last 43 years. It is compact and would be easy to set up along a small bearing mounted bench spindle. Just have to figure out the size of the pulleys and draw up a precision jig for the bits, probably the hardest part to make. Thanks for your input. Best, JHM
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I would set it up with a smallish (50 - 100 mm) diamond grinding wheel, preferably with a flat face (a cup wheel) for tool sharpening. My experiments so far suggest a diamond wheel can give a much sharper edge bu removes metal at a reasonable rate, at least for a small toolbit. At the same time it produces far less noise, smoke and dust than a normal grit wheel. Yes, you could sell it, but alternatively you could use it. Use would almost certainly be intermittent and brief.
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Re: Spindle ball bearings for Unimat 3 (2023)
Hello All,
Thank you all for detailed information on?this question!?
I got a pair of SKF 6003-2Z bearings from a US ebay seller (item 163649829660). These installed fine and measure around 0.015 mm runout if my measurements are correct.
Kind Regards, Andrey
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?¦Ìm
Normal 3 - 18?¦Ìm?
C3? 11 - 25?¦Ìm
C4? 16 - 33?¦Ìm?
C5? 25 - 45?¦Ìm
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.
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Re: Unimat Extended Travel Quill
Though if the regular drive is powerful enough something like this that slides inside the spindle would be much simpler to make 
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On Wed, Feb 15, 2023 at 06:00 PM, Mike wrote:
... the original set up on my milling machine attachment.
As my Unimat 3 came with a Unimat milling table/head combination, I just added a new 24v / 200W motor with electronic speed control like the one I have on the lathe. All I have to do is switch the PS from one to the other when using the mill. If for whatever reason I ever have to mill a piece on the U3 itself, I can always set up the column on it in a short while. Rather a hassle if it is for a small/short job, but perfectly doable. Thanks so much for your input. Best, JHM
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Re: Unimat Extended Travel Quill
Thanks. I use the shinier quill on the right in that picture for grinding, too. Here¡¯s one I sketched up one for drilling bigger stuff using parts from a cordless drill - maybe the housing for that could be 3d printed. 
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Hello JHM, I have a new(ish) variable speed motor for my U3. I have the original set up on my milling machine attachment. Good to have the versatility of being able to use it in conjunction with the lathe. There are always some projects that would benefit from this versatility. Mike Szreider UK U3 owner.
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On Wed, Feb 15, 2023 at 04:43 PM, Andrey Malakov (gmail) wrote:
... even harder to find than DB/SL ones.? ... sell it to somebody who needs one.
I first thought of doing exactly that. But then I thought ... Who would want to spend US$XXX+shipping to replace a Unimat 3 motor of excellent albeit very limited, for another one just like it? What would be the benefit in doing so when a very decent DC motor+controller solution can be had for less than US$30+shipping? That said and notwithstanding my OP, should anyone be interested, do drop me a line. Thanks for your input. Best, JHM
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My 2 cents: U3 motors are even harder to find than DB/SL ones.? My advice - sell it to somebody who needs one. They fetch around 200 US excluding?shipping.
On Wed, Feb 15, 2023 at 9:56 AM Julius Henry Marx < sawbona@...> wrote: Hello:
Like many other Unimat lathe owners, I have installed a new 24v / 200W motor with electronic speed control on the U3.
Works a wonder, does not overheat, recovers gracefully from mistakes (stalling)? and is very silent.
So I am now faced with finding something to put the OEM motor to good use, if at all possible.
I understand that there is more than one version of this motor, depending on the manufacturing date on the lathe.
My U3 lathe has serial #80070243, so it is from 07/1980 and close to 43 years old.
Just like the motor, which seems to have the orignal carbon brushes with ~50% still left on them.
The motor's stick-on label has a "Gefeg"* logo and reads:
----
Typ Ug720-2S
220v ~ 50Hz (c/s)
95/65W S3-80% 5000/6000/min
Intermittent duty ON 8min/ OFF 2min
Made in Germany
----
No serial number on it.
*
So the question is: has anyone here repurposed their retired Unimat motor for anything worthwhile?
Obviously, the unavoidable 8m/2m intermittent duty spec limits the alternative uses this motor could eventually have, but I was wondering if it could be used to build something which does not require more than 8' use each time.
eg: running a 100/120mm diamond wheel for the finishing or retouching of HSS tools.
Those are the ones most of us end up using after giving up on brazed carbide and indexable insert tools and must be sharp.
I'd appreciate any insight on this.
Thanks in advance,
JHM
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Hello:
Like many other Unimat lathe owners, I have installed a new 24v / 200W motor with electronic speed control on the U3.
Works a wonder, does not overheat, recovers gracefully from mistakes (stalling)? and is very silent.
So I am now faced with finding something to put the OEM motor to good use, if at all possible.
I understand that there is more than one version of this motor, depending on the manufacturing date on the lathe.
My U3 lathe has serial #80070243, so it is from 07/1980 and close to 43 years old.
Just like the motor, which seems to have the orignal carbon brushes with ~50% still left on them.
The motor's stick-on label has a "Gefeg"* logo and reads:
----
Typ Ug720-2S
220v ~ 50Hz (c/s)
95/65W S3-80% 5000/6000/min
Intermittent duty ON 8min/ OFF 2min
Made in Germany
----
No serial number on it.
*
So the question is: has anyone here repurposed their retired Unimat motor for anything worthwhile?
Obviously, the unavoidable 8m/2m intermittent duty spec limits the alternative uses this motor could eventually have, but I was wondering if it could be used to build something which does not require more than 8' use each time.
eg: running a 100/120mm diamond wheel for the finishing or retouching of HSS tools.
Those are the ones most of us end up using after giving up on brazed carbide and indexable insert tools and must be sharp.
I'd appreciate any insight on this.
Thanks in advance,
JHM
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Re: Emco Compact 5 Mill Motor Internal Bearings
Yea! I love a good ending! And if you hadn't had the problem, you wouldn't have learned as much about the machine, too! I keep acquiring broken and damaged equipment, too. Mostly because I'm too cheap to buy it all new, but hey, I'm learning about it while I fix it! That's my story, and I'm sticking to it!
Bill in OKC
William R. Meyers, MSgt, USAF(Ret.)
Aphorisms to live by: Good judgement comes from experience. Experience comes from bad judgement.? SEMPER GUMBY!
On Tuesday, February 14, 2023 at 07:09:16?PM CST, Djed.geo via groups.io <djed.geo@...> wrote:
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!!
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Re: Unimat Extended Travel Quill
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
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Re: Emco Compact 5 Mill Motor Internal Bearings
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!!
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Re: Spindle ball bearings for Unimat 3 (2023)
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?
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Re: Spindle ball bearings for Unimat 3 (2023)
I suggest 6003-2RS bearings (IE sealed), normal or C3 depending on what is readily available. Use SKF or another respectable bearing company, not cheapo ones from China (except that some SKF bearings are made in China, but still seem to be good). Here in the UK we would pay ?4 or 5 each for them.
A quick look around Ebay.com finds item 133835772483 for $10 each. Most of the USA stocked items seem to be SKF, so that seems like a good choice. Prices generally seem to be around $10 each. Ignore anything from outside the USA. In this case it's best to have a more local supplier, and that still gives plenty of choice.?If you don't use Ebay there should still be a supplier near you.?The cheaper anonymous bearings from China and elsewhere are not to be trusted for a critical application, and to my way of thinking that's what this is. You want the bearings to last forever, ideally, so get good ones!
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Re: Spindle ball bearings for Unimat 3 (2023)
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.
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Re: Spindle ball bearings for Unimat 3 (2023)
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.
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Re: Spindle ball bearings for Unimat 3 (2023)
Hello:
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On Mon, Feb 13, 2023 at 04:15 AM, Keith S. Angus wrote:
According to the SKF handbook, and my experience, C3 is not the usual bearing everyone uses ...
I see. Just quoting a source, have no idea.? 8^/ Thank you very much for the heads-up.
A Normal bearing has no extra markings on it.
So the SKF samples I installed, which I do not recall having any markings on the box, would be 'Normal'. ie: C2
If the bearing is tight on the shaft AND in the housing a C3 bearing is used ...
I don't recall the bearings being a tight fit when I mounted them.
On the U3 the bearings have an axial preload ...
Yes, had rather a hard time fitting the whole assembly back in but finally succeeded.
... so I would look for a C3 or C4 bearing.
If I ever have to change the bearings again, I'll remember this.
... the SKF 7003CD bearing will fit. ... but they cost about ?120 each ...
Indeed ... That is well over ~10x as much as the pair of SKFs I purchased cost me. I have come to learn that precision gets exponentially expensive as requirements go up. And that there never seems to be something in the middle. This has been quite an eye opener, thank you very much for you input. Best, JHM
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Re: Spindle ball bearings for Unimat 3 (2023)
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?¦Ìm Normal 3 - 18?¦Ìm? C3? 11 - 25?¦Ìm C4? 16 - 33?¦Ìm? C5? 25 - 45?¦Ìm 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.
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Bill in OKC too
OldToolmaker