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Emco Mill bent spindle mystery

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Ian P08/07/2011 08:18:47
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Following up on my ''Quill fit improvement'' topic I have uploaded some pictures of the spindle that came out of a machine I bought recently.
 
The photos are in an album I have just created but I am not sure how to link to it but I think I named it ''Emco Mill Pictures''.
 
The spindle is about 200mm long overall and the front needle roller journal is 30mm diameter, the section between the bearings is 29.5mm and is about 60mm long before the 20mm diameter seat for the upper pair of angular contact races.
 
In the section between the bearings the spindle is bent! Or at least its distorted in some way.
 
One picture show the pitting and uneven wear on the front track and another shows the fit of the MT2 adapter.
 
The adapter that came with the machine is a high quality Swiss, Schaublin item and if I put it in the spindle taper and rotate it with slight pressure it has a very distinct uneven rotation as if the adapter as well as the bore is ovel in some way.
 
I doubt whether the machine is robust enough to have the force and inertia to bend the spindle whilst in even abnormal use, but I have now spent some time examining the spindle and can definately say the that the two bearing surfaces are not in line, and the taper bore is not truly concentric.
 
Ian
 
 
 
John Stevenson08/07/2011 08:44:58
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What a horrible design.
 
I have a genuine Jacobs revolting centre that is the same as this. It has very slight play in the needle roller bearing and so the whole assembly is junk in that there is no adjustment or means to replace the lower / front bearing and or tracks.
 
Same applies here
 
In this design it has a pair of angular contacts at the top where they are doing the least good.
 
Is this the Australian export model ?
 
I was going to suggest you make a new spindle using the existing quill but from your previous post you have problems with that as well ? Probably best to bung it on Ebay and replace the whole machine
 
John S.
ady08/07/2011 09:24:08
612 forum posts
50 photos
The tube section at the top looks exactly the same as one from a unimat sl.
Emco probably interused parts where possible.
 
Not a very stiff or secure design, but they were always well made.
Any roller bearing issues effectively rendered the lathe almost useless.
There should be a ballrace surface at each end of the spindle tube you can tap out.
I found that all my old emco bits were very well made and good to 100th of a millimeter.
 
Someone probbly took it apart at one point and stood on it by accident kinda thing.
Old emcos seem to have led exciting lives because a lot of total boo-boos buy them as a first ever unit and then take them to bits.
A unimat sl with a disaster zone for a headstock was what got this particular boo-boo into metalwork a few years ago.
 
 

Edited By ady on 08/07/2011 09:28:44

Ian P08/07/2011 15:10:13
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2552 forum posts
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To
Posted by John Stevenson on 08/07/2011 08:44:58:
What a horrible design.
 
I have a genuine Jacobs revolting centre that is the same as this. It has very slight play in the needle roller bearing and so the whole assembly is junk in that there is no adjustment or means to replace the lower / front bearing and or tracks.
 
Same applies here
 
In this design it has a pair of angular contacts at the top where they are doing the least good.
 
Is this the Australian export model ?
 
I was going to suggest you make a new spindle using the existing quill but from your previous post you have problems with that as well ? Probably best to bung it on Ebay and replace the whole machine
 
John S.
 
 
John
 
Well that's an honest opinion of Emco's design!
 
You are right though, having a non adjustable needle roller at the bottom end of the spindle is a flawed idea, One of my rotating centres actually has an adjustable parallel needle roller bearing which is what Emco could have done.
 
I have now made a completely new spindle for the same quill body so it now has two conventional taper roller races. I've done away with the MT2 bore and have an integral ER25 taper. The loss of the Morse tapers is easily overcome as I will make a drill chuck arbour with 16mm parallel stub, any other tooling, like a fly cutter I will make to suit anyway.
 
I was unaware there was an antipodean version of the mill, but its not impossible.
 
Because the slides and basic parts of the machine are in such good condition I want to solve the problem of the slack quill and I will then have a nice machine. I did consider selling it on Ebay or whatever but I would be duty bound to describe it honestly which would limit what it might sell for.
 
Ian
 
Ian P08/07/2011 15:21:10
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2552 forum posts
113 photos
Posted by ady on 08/07/2011 09:24:08:
The tube section at the top looks exactly the same as one from a unimat sl.
Emco probably interused parts where possible.
 
Not a very stiff or secure design, but they were always well made.
Any roller bearing issues effectively rendered the lathe almost useless.
There should be a ballrace surface at each end of the spindle tube you can tap out.
I found that all my old emco bits were very well made and good to 100th of a millimeter.
 
Someone probbly took it apart at one point and stood on it by accident kinda thing.
Old emcos seem to have led exciting lives because a lot of total boo-boos buy them as a first ever unit and then take them to bits.
A unimat sl with a disaster zone for a headstock was what got this particular boo-boo into metalwork a few years ago.

Edited By ady on 08/07/2011 09:28:44

The quill design of the mill has nothing in common with the SL other than the external appearance of the body. I am not sure what you mean about roller bearing issues with the SL lathe, as that had angular contact ball races, actually the SL mains spindle was quite adequate for its purpose and mine has had hundreds of hours use (and abuse). It does not get used now I have another lathe but its still on its original rubber belts!
 
Although I have described the distortion in my mill spindle as a bend, its a bit more complex than that. the unground section between the bearings has the makings of being bent but its also not truly circular.
 
Ian
blowlamp08/07/2011 15:28:39
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1530 forum posts
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Posted by Ian P on 08/07/2011 15:10:13:
 
 
...I was unaware there was an antipodean version of the mill, but its not impossible...
 
 
Ian
 
 
I think John means that the bearing arrangement is upside down to how it should be, for best effect.
 
I must agree that it is a poor design thought.
 
Martin.
ColH11/07/2011 04:51:01
28 forum posts
Hi Ian
 
Couldn't find your other thread.
 
What model Mill was it?
 
Col
Ian P11/07/2011 09:43:52
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2552 forum posts
113 photos
Posted by ColH on 11/07/2011 04:51:01:
Hi Ian
 
Couldn't find your other thread.
 
What model Mill was it?
 
Col

Col
 
The topic was titled 'Improving fit of quill in casting' (or something like that anyway).
 
This should link to it though
ColH12/07/2011 00:10:38
28 forum posts
Thanks Ian
 
Usual story - hit the send button and you find what you are looking for. Just like the tool fairys in the workshop who hide a tool until you give up looking and then return it later to a place you had previously searched.
 
Col
Ian P16/05/2012 23:02:15
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2552 forum posts
113 photos

Graham

Put simply, its not going to fit!

The quill on the Mentor mill (4 speed head) is 48mm diameter. I have done a CAD drawing of the whole spindle assembly and it its any use to you I can send the file.

Regards

Ian

Raymond Griffin17/05/2012 21:09:55
54 forum posts
42 photos

I’m not sure if my experience with my EMCO mill is helpful, but add my thoughts. I purchased an EMCO FB-2E mill fifteen years ago. I had the choice between the one made in Austria FB-2 and the equivalent made “in the East” designated FB-2E. I purchased the FB-2E as it was considerably cheaper than the Austrian version, and I was assured that EMCO were vigilant in quality control of the Eastern model. As usual, you get what you pay for and for some time I wished that I had found the extra cash and bought the Austrian model. Eventually I managed to get the machine into a satisfactory state. The table was jerky in its x and y movement and I had to completely strip it down and replace all the solidified grease. The grease formed solid lumps in the bearings of the hand wheels. After a couple of years play developed in the roller bearing of the spindle. The area of the quill around the roller bearing also became hot on the highest speed. With some trepidation and difficulty, I dismantled the quill and found gritty residue in the region of the rollers. Quite obvious really as it is the lowest point in the system and debris in the oil will descend into the roller bearing. I imagine that the debris results from inadequate cleaning in the factory at assembly. I saw that the bearing surface was scuffed but left it alone, not knowing what to do. I purchased a new roller assembly from EMCO and as the unit was disassembled decided to fit a new thrust bearing also. I put it all back together with the new bearings. I also replaced the oil as the original stuff looked terrible. You can imagine my disappointment when I found that the play in the spindle was reduced but not gone. I was going through options with a friend well versed in machine tool matters and he suggested that the roller bearing design would make it difficult to eradicate side play. He suggested that I replace the existing bearing with a bronze bush. I scoffed at the idea at first as being beyond my capabilities. I then came to the conclusion to have a go, as the machine was useless for accurate work. The quill was again stripped into components. I put the spindle in the lathe and polished the bearing surface with fine silicon carbide paper followed with metal polish. Mine was not as badly marked as the one shown in the photo. I then found a suitable piece of bronze in my store and turned up a bush that was a firm fit in the quill and a very tight fit on the spindle. I also drilled an oil way to the centre of the bearing. The spindle was put in the lathe with the bush in place together with some metal polish. I use Autosol for these jobs. The lathe was started at a slow speed and I held the bush against rotation. It was hard to hold the bush at first but became easier. I changed the metal polish a few times as I had heard that the cutting action of Autosol reduces as the particles in the polish break down and become less effective. Eventually I had a smooth running bearing with no play. All was put back in place and happily the spindle rotated freely with no side play. It has now been used regularly for several years and no play has developed. The sole problem is a very minor oil leak around the spindle. It is not sufficient to be a nuisance and proves that oil is getting into the bearing so I leave it alone. Perhaps I should have replaced the oil seal when the bronze bush was fitted. I cannot comment on the bent spindle except to express surprise as it seems a very sturdy construction. After all this I am now content with my machine. It is sturdy for its size and produces good results. I might add that the gearbox was noisy in the early days but following the addition of some molybdenum sulphide additive sold for motor car engines it runs quieter and smoothly. I hope that this is a useful contribution.

Raymond Griffin22/05/2012 20:08:07
54 forum posts
42 photos

Hello Gray,

Very many thanks for the data on the rollers. It reminds me of my AJS motorcycle in the 1950’s. The big end became noisy so I had it rectified. The mechanic told me that he had fitted oversized rollers to take up the slack. My Pitman’s “Book of the AJS” notes that oversize rollers 0.001in. were available but the journal and liner needed to be lapped by a skilled mechanic.

I am extremely grateful for your comments on the oil leak and how to cure it. The spring loaded ball valve will be high on my list of jobs. Until then I may slacken the plastic oil filler cap to allow air pressure to equilibrate. I had a problem with my FB2 in the early days in that the compressible nut on the Z direction screw rapidly became fully collapsed, so it became difficult to take up play. I replaced the nut which enabled me to take up play, but do wonder how long this will continue. Do you have experience of this?

Ray

Raymond Griffin30/05/2012 16:50:09
54 forum posts
42 photos

Hello Gray,

Sorry for the tardy reply, but we took a few (sunny) days in Cardiff on family business, without the laptop. I must complement you on the excellence of your pictures. The super machining and the high quality photos are a joy to the eye. I attach a photo of the old roller assembly take from my FB2.

Ray

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