Headstock bearings under tailstock pressure

MatDart · Oct 7, 2024

I have an Emco Compact 8E - that is the Chinese made-for-Emco lathe... I think it is the start of all the small Chinese made lathes!
It has a simple headstock bearing arrangement with two taper-roller bearings - on the drive end there is threaded the maingear and the keyed-drive pulley, held on with a single nut (C-spanner type that has a little locking grub screw to bear on the mandrel thread (!) I have put a little slug of brass between the screw and the thread).
So pre-load of the bearings is determined by the tightening of that c-spanner nut and that is all very well - I can set it so that the mandrel is free-running. The mandrel seems to be a tight fit in the bearings and I have not had it out.
The problem I have is that when I put pressure on the work with the tailstock ball bearing centre, the headstock bearings bind. I can't find a way to resist movement of the spindle that puts pressure on the head bearing.
It feels as though I am missing something simple! I'd be very grateful for any help.
Mat

Jasonb · Oct 7, 2024

I used to have an Emcomat 8.6 which was the Austrian made geared head version of the C8. Unless you are putting far too much pressure on the tailstock the bearings should not be going tight when you use it.

Are you checking the preload on a warmed up machine or one that has been stood in a cold workshop, It should be run at mid speed for at least 20mins before you set the bearings. Also make sure they have some grease in them, the lathe is getting on now and old grease may have been lost or dried out over time.

MatDart · Oct 7, 2024

Thanks for your reply Jason - your Austrian made one will be much better made than this one!.
I have tested even with the locking nut backed right off - and even mild pressure with the tailstock still causes binding.
I will check the grease situation again - but finding it difficult to get access to the open side of the bearing inside the headstock box.
I haven't been able to remove the mandrel to check the bearing from the outside.
It does seem to spin freely without any nasty noises or play when there is no pressure from the tailstock.
Thanks again!

kf2qd · Oct 7, 2024

Sounds like you need to pull the spindle and check all the clearances behind the bearing next to the chuck. If it is tightening up under tailstock pressure that would suggest there is some part of the spindle/head stock that has minimum clearance.

Jasonb · Oct 8, 2024

Yes the spindle really needs to come out to check the bearings and that they all is well, try it at each stage of disassembly rotating the chuck by hand as it will help show if a part is hitting something.

The Chinese machine that I have now has no issues with the spindle going tight and although made in China the Emcos were built to a tigher spec. Not heard of any with your problem.

MatDart · Oct 8, 2024

Thanks Chaps - Yes I will have to find a way to remove the spindle. I have given it a few tentative taps with a mallet - no movement at all so far... I don't fancy bashing it too hard so will have to fettle up some kind of extractor I guess..
Any suggestions for that would also be gratefully received!

abby · Oct 8, 2024

I had the Emcomat 7 for several years and I seem to remember that the headstock casting was actually an oil bath , is this not the case with your lathe?
I thought the lathe to be very accurate but a little lightweight in parts , unfortunately, when the built-in electrics failed and spares were impossible to find it had to go.
Dan.

Jasonb · Oct 8, 2024

The Compact 8 is belt drive, not the gears and two speed motor of the Ecomats. Same bed, carriage etc though

You may have to put some bolts through the chuck mounting flange and nuts behind and use thos eto jack the spindle out of teh head. Put some flat plate under the ends of the bolts so save damage to the headstock casting.

MatDart · Oct 8, 2024

The 'Compact' 8 is/was a simplified and cheaper lathe of similar size to the Emcomat 7 - it has belt drive and a simple box headstock with 2 bearings.
They were originally made by Emco and coloured yellow; my one is red and grey and was made in Taiwan - so is called Compact 8E (for 'Eastern') - and you can easily see differences in quality control! Also it has even more simplifications in the drive train and eleswhere... but is still a pretty good, fairly rigid and heavy bit of kit.

MatDart · Oct 8, 2024

Jasonb said:
The Compact 8 is belt drive, not the gears and two speed motor of the Ecomats. Same bed, carriage etc though

You may have to put some bolts through the chuck mounting flange and nuts behind and use thos eto jack the spindle out of teh head. Put some flat plate under the ends of the bolts so save damage to the headstock casting.

Great ideas thanks Jason... I'm not going to get a chance to do this for a week or more now - have to go away for work... but will let you know how I get on.

clockworkcheval · Oct 8, 2024

In the workshop of our horological society we have besides four Schaublin 102 lathes also two EMCO Compact 8 lathes. In our experience the headstock bearings need replacement about every ten years.

Jasonb · Oct 8, 2024

How many hours of use would that equate to? Yearly is not a good indicator as they could be getting used daily, weekly on only when the Schaublin's are all in use.

clockworkcheval · Oct 8, 2024

Our workshop is every weekday in use by about 10 members of our 100 member group. A rough guess is that the Emco's are used each about 10 hours per week during 40 active weeks per annum. That would make in ten years time 10x40x10 = 4.000 hours.

Ken I · Oct 8, 2024

I'm going to take a flyer on this one - my experience with Chinesium is that they will put in anything that fits.

I'm guessing those are supposed to be "deep groove" ball bearings which can handle moderate axial thrust and they have used a shallow groove of the same dimensions.

Look up the bearing number or check with a bearing supplier.

Regards, Ken I

MatDart · Oct 8, 2024

Thanks again everyone - yes Ken, I'll have a fiver on that being the case.
And Mr Clockwork thanks - good to know what to expect re life of bearings - I don't know how much use this got before I got it (in jewellery dept of a college) but those 4,000 hours use will see me out! If/when I put in new bearings that is - would you be able to tell me the number of the bearings you use please?
Cheers
Mat

MatDart · Oct 8, 2024

I just found this comment on a thread on another forum - sounds like the right way to do it:

The Compact 8 spindle is a precision piece; I would not take a mallet or hammer to it if I were you. You have two options: 1) remove the headstock and move it to a press and push the spindle out, or 2) use a threaded rod through the spindle (protect the taper) and pull it out as @4gsr suggested. Most of the guys on the Emco Larger Lathe group do it this way. A piece of PVC pipe that goes over the chuck mount, a large plate to span the pipe and pass the rod throught (instead of a large washer), and a nut on the threaded rod completes the front set up. In the rear, a large washer and nut to bear on the rear of the spindle. Then come up front and turn the nut and pull the spindle out.

Please do not hammer on your spindle. Nothing on any Emco lathe requires force other than bearing fits and even that is only 0.0002" at most.

clockworkcheval · Oct 8, 2024

MatDart said:
Thanks again everyone - yes Ken, I'll have a fiver on that being the case.
And Mr Clockwork thanks - good to know what to expect re life of bearings - I don't know how much use this got before I got it (in jewellery dept of a college) but those 4,000 hours use will see me out! If/when I put in new bearings that is - would you be able to tell me the number of the bearings you use please?
Cheers
Mat

Hi Mat, another of our members has done the replacements; what I know is that the Emco's run very well again! In my own workshop I have different machines to take care about: GOTHA Tool and Cutter grinder from about 1937 under restauration, TAIG lathe, SOLID Pillar Drill, Myford Super Seven, Schaublin 102VM lathe, Aciera F3 milling machine, WABECO F1200 milling machine, Tormek wet grinder.

Jasonb · Oct 8, 2024

The Compact 8 takes 32007XC P6 bearings, not sur ewhet the 8E may have

However the common 918 Emco clones also have 32007 taper Roller bearings so quite likely the 8E does too.

MatDart · Oct 8, 2024

Thanks Jason - I just looked up those 32007s and they're Very cheap! I will get on and order some as soon as I have made sure I am on to a good brand.
Cheers again
Clockwork-man: What a fabulous lot of machines! And such a tidy workshop!! puts my efforts to shame.
I have also a harrison L5 long bed & a nice old American pillar drill.... and an old Denford wood lathe... not so much to show!

MatDart · Oct 20, 2024

Well no luck so far - I tried:
Length of 10mm studding with nuts and 4mm thick plate washer on the outer end, and a sweetcorn tin can for a spacer over the chuck flange, plywood plate and thick washer at the chuck end. On tightening the mandrel did not budge at all, and eventually the tin can started to collapse (inevitably!).
I gave the studding end a couple of taps with the mallet while still under tension - but am still being very cautious with that!
So the mandrel is jammed tight in the outer bearing, and possibly in both, and the chuck end bearing did not shift in its seat.

I thought it might be good if I could chill the mandrel to shrink it a bit and possibly break the lock on the bearing - but the only way I could think of was to chill a length of 19mm steel bar in the freezer, then put it inside the mandrel bore and leave for a few minutes. The mandrel definitely got cold - but still no luck getting it to shift.
So I am a bit fed up and will leave it till I find something better than that tin can.... and maybe some heftier studding.

The bearings are definitely ball-race and not tapers... I wonder if even the proper Compact 8 has these? Mine seem to run smoothly so I tried again to get some grease into them from inside the headstock (they are sealed on the outer faces only) - but access is very difficult.
Still, something has improved as they don't seem to bind so much when under tailstock pressure now...
But I will definitely have a go at replacing them with taper rollers if I can get them out - I am surprised at how cheap even decent ones are - £23.50 for SKF and half that for Dunlop...

Thanks again for all the help so far!
Mat

Headstock bearings under tailstock pressure

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