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Lathe Maintenance Questions

tcncj

Cast Iron
Joined
Dec 15, 2016
Hi all,

I bought my first CNC lathe this year. It's an Emcoturn 240 made in Austria. I don't know the exact date when this machine was made but it's around 1989.

Most of my parts are small and I only make around 10 different parts. Buying a new lathe wasn't the best option and I didn't want to spend more than 15.000 on a used old machine.
So I found an Emco, it seems they are accurate and hold tolerances very well when I did some research about these machines. I bought one in good condition and very cheap. Controls are old of course and when I first started the machine I felt like I entered The Matrix when the green letters showed up. I had no experience with 'real' controls and for a couple of days I played around with the machine. It had a serial interface though. But I wasn't too happy. I'm no real machinist, I just want to draw my part in CAD/CAM and transfer the stuff to the machine and hit the green button. I'm too lazy to program at the machine.

So within a week I started removing all the electronics and started a retrofit.
Pretty easy to convert everything. Most time went into the configuration and fine tuning.

Oh some specifications of the machine:
4.000RPM
53mm spindle bore
Turning Length: 340mm
8 Position turret
5.5kw/7.5hp spindle
Rigid tapping
And I'm thinking about adding a C-axis

Things I don't like about the machine are that when the tailstock is moved forward. The x-axis doesn't have allot of travel before it crashes into the tailstock. It's not an automatic tailstock and it's bloody heavy to pull/push the tailstock each time. I still have to find a solution for it...

So for half a year I did some work with the machine and very happy with it. They indeed hold tolerances well trough the day.
Now at the end of this year I want to make the lathe ready for 2018. I wont sell it because it's such a small and good lathe. And started cleaning everything. The central lubing system was clogged. Allot of brass chips mixed with green old oil that was everywhere! I removed all panels and it seems the box ways and ballscrews are still in good condition. The machine was used on a shool so I think it didn't saw allot of production.


But I have some questions regarding the lubrication of the ballscrews/angular contact bearings and spindle bearings.

* The spindle runs smooth and it doesn't make strange sounds. Should I put new lube in the spindle bearings?

* The ballscrew nuts do have grease nipples. I will put some new grease in it. But what about the angular contact bearing block? Should I remove old grease and apply new grease?

* The machine had 0,04mm backlash on the X and Z axis. I 'solved' it by configuring backlash compensation. I will be replacing all belts (axis motors and ballscrew is connected with pulleys and a belt) and I hope this solves it. The machine still had the original belts.

* the box way wipers where almost all gone. Anyone knows where to get new ons? See picture below

* Anyone knows where the screws in the x-axis (under the turret) are for?

Some pictures:

Old grease behind the covers
ltxSABO.jpg


WQUj4cQ.jpg


Cleaned
A6biSQp.jpg



X axis cleaned
vhLhaUT.jpg


Ef4KLGt.jpg


SjD325B.jpg


Fr4Qp29.jpg


5qnTvzc.jpg


kOutN88.jpg
 
Remember the prime directive: If it ain't broke, don't fix it.

I don't know what the screws are for. Possibly they are plugs for oil passages for the lube system.

I don't know a UK source for the wipers, but there are standard sections available in meter lengths. Just cut and drill to fit.
 
Thanks for the information

Yes! those are the wipers I need

Ok I won't touch the spindle and angular contact bearings then :)
 
Machine builders many times call a spindle head permanently greased bearings and I would suggest leaving them alone if your not experiencing any problems. The flat head screws under the turret I would suspect are plugs and only keep crud out of them. Used when another unit is bolted there. Remove only one and see?

The set screw on the rear headstock bolt as shown in the 7th picture is used when aligning the headstock point up. I would not remove it if the machine was turning or boring OK.

It appears the machine uses needle bearing packs and the vertical stripes were made when the machine set idle for years and the hardened way corroded a bit. Not much you can do accept clean with scotch brite and cross your fingers. If you have loosened the ball screw nuts from the slides I would suggest leaving the bolts loose or only snug until you can move the head or turret unit to the end bearing brackets as close as possible to get proper alignment, then tighten the bolts.

In a recent class in Germany, 2 of my students were or are professional machine rebuilders from Austria.
Franz and Stephan Luftinyer and there email is [email protected] and I would bet they would give you some help if you need it. Tell them I said hello.
 
Depending how old everything is, you might want to re-grease....
Well...I think everything is untouched when it left the factory at 1989 haha. So also grease from 1989.
Machine is in very good condition though. I think it isn't used for years because it was standing at a shool.


Machine builders many times call a spindle head permanently greased bearings and I would suggest leaving them alone if your not experiencing any problems. The flat head screws under the turret I would suspect are plugs and only keep crud out of them. Used when another unit is bolted there. Remove only one and see?

The set screw on the rear headstock bolt as shown in the 7th picture is used when aligning the headstock point up. I would not remove it if the machine was turning or boring OK.

It appears the machine uses needle bearing packs and the vertical stripes were made when the machine set idle for years and the hardened way corroded a bit. Not much you can do accept clean with scotch brite and cross your fingers. If you have loosened the ball screw nuts from the slides I would suggest leaving the bolts loose or only snug until you can move the head or turret unit to the end bearing brackets as close as possible to get proper alignment, then tighten the bolts.

In a recent class in Germany, 2 of my students were or are professional machine rebuilders from Austria.
Franz and Stephan Luftinyer and there email is [email protected] and I would bet they would give you some help if you need it. Tell them I said hello.

I will check what's under the screws tomorrow.
I don't care about the vertical stripes on the box ways. I can't feel them. Everything is smooth. I won't touch the spindle head. The spindle head was adjusted when I bought the machine by a local emco service point to align everything.
 
I won't touch the spindle head. The spindle head was adjusted when I bought the machine by a local emco service point to align everything.

The smart thing to do is to chat with the local EMCO agent, THIRTY years is a bit on the much side. Grease inside may look fine and may feel smooth but it has lost quite a bit of it's oil and that's for sure. When these things die, they die quickly and once it gives signs of trouble it's too late - only quick downhill from there. I wouldn't second guess the manufacturer here.
You'll need to re-grease the linear rail blocks. Again, see what the manuf recommends. If you do a lot of short moves you'll absolutely need a vibration proof grease. Pump enough grease so that quite a bit emerges from under the seals, run long strokes for some time and then pump again until enough emerges. The linear rails are a special selection - frightfully expensive compared with normal, transport grade ones.
 
It doesn't have linear blocks/rails, it's a box way machine. So it will need way oil.
I cleaned the central lubing system for the way oil/box ways. So that should be good
The ballscrew nut uses grease. Not connected to the central lubing of course. I will regrease the ballscrew nuts anyway.

I can pull the spindle and angular contact bearing house apart. That's not a problem. But I don't know the preload that's needed for the bearings.
So I don't think it's a good idea to tear them apart.
 
It doesn't have linear blocks/rails, it's a box way machine. So it will need way oil.
I cleaned the central lubing system for the way oil/box ways. So that should be good
The ballscrew nut uses grease. Not connected to the central lubing of course. I will regrease the ballscrew nuts anyway.

I can pull the spindle apart and angular contact bearing house apart. That's not a problem. But I don't know the preload that's needed for the bearings.

That's much nicer, then. There is a smaller version around here with linear rails and blocks. Maybe fine but definitely not long lasting.
 
Besides I think I know where the screw holes are for in the x axis under the turret.
I compared some other Emco's and it seems it's possible to lower the turret. This way the x axis wont crash into the tailstock!
 
I can pull the spindle and angular contact bearing house apart. That's not a problem. But I don't know the preload that's needed for the bearings.
So I don't think it's a good idea to tear them apart.

In all probability the preload is fixed. Pull apart, clean, grease and put it back as it was. I am not advising you to do anything but I would surely not run a spindle with 30 y/o grease inside. When they start going downhill it could be 10 minutes between fine and needs rebuild.
 
I just couldn't install everything back without checking the spindle.
Looks like very old grease to me...
They all still run smooth though.
4 angular contact bearings

What's the best way to remove the bearings?
Use a heat gun?

Edit: found some useful information
How to Replace CNC Spindle Bearing Part 2

JoHHTx4.jpg


S1OXfZr.jpg
 
Do NOT use a heat gun. Old phenolic cages may disintegrate. Hold the sleeve and strike the other end with a light steel hammer through some sort of "interface". Depending on how much fretting corrosion there is underneath it should start to move. Take some pics of the front so I can see how that looks like. The grease looks like Kluber NBU15 well aged. You'll discover now why you need a 2nd lathe to fix a lathe. :)
 
Check in the face holes on the front of the spindle and see if there are through holes to the bearing inner race and then use a pin punch to tap thru the hole to tap off the bearings. One hit in the 2 holes at a time to not cock the bearings. If there are not holes, lay a 1/2" sheet of plywood approx 20" x 20" on the concrete floor or on a cast iron heavy duty table then put a, Oak 2" x 4" x 12" on top of the plywood. The put the spanner nut back on the end of the spindle. Screw it on so it is flush with the end of the spindle. Then raise by hand (making sure your fingers are out of the way) the spindle up about 6" above the wood and move it down fast and the force of the motion and it stopping fast will use momentum to force the bearings down and off. The bearing normally are replaced so the possibly of damaging the bearings or peening the balls into the races isn't worried about. Give it a go and see what happens.
 
Check in the face holes on the front of the spindle and see if there are through holes to the bearing inner race and then use a pin punch to tap thru the hole to tap off the bearings. One hit in the 2 holes at a time to not cock the bearings. If there are not holes, lay a 1/2" sheet of plywood approx 20" x 20" on the concrete floor or on a cast iron heavy duty table then put a, Oak 2" x 4" x 12" on top of the plywood. The put the spanner nut back on the end of the spindle. Screw it on so it is flush with the end of the spindle. Then raise by hand (making sure your fingers are out of the way) the spindle up about 6" above the wood and move it down fast and the force of the motion and it stopping fast will use momentum to force the bearings down and off. The bearing normally are replaced so the possibly of damaging the bearings or peening the balls into the races isn't worried about. Give it a go and see what happens.

Another vote here for that method. Simple but normally effective.

Regards Tyrone.
 
Thanks for the information
Yes I checked the bearing and didn't used the heatgun because of the cages.

I will try above method and I hope I don't damage the bearings...
 
Also check for the * mark on the inner races. It could be a small grind mark in a circle. That is the TIR mark which is mounted 180 degree's of the TIR mark on the spindle.But to be safe if your not going to replace the bearings scribe a mark on the spindle where the * is at now and be sure to put it back on aligned with that mark. Also I would use Isoflex grease packed at 20% full or Mobil 28 or 32 packed at 30%. I hope you marked the spanner nut with a mark to where it was located when you took it off. You can see what I wrote in the Clausing Mill thread and save me some writing. Rich

PS: also some bearings are marked on the outer race with a sideways V mark so you get the outer races lined up.
 
I placed the spindle between two wooden blocks and tapped it very lightly with some wood between. It took some time but they came off eventually. I couldn't spot any TIR marks on the spindle. The bearings had a mark. I marked the spindle so I can line up everything.
Bearings run smooth and there doesn't seem any damage. Only problem is that the cage one bearing came loose and some balls fell out. I have them and they don't have any damage. Inner and outer race look also fine. I hope I don't have to buy a new bearing for this one

I have Mobil grease that came with my Haas mill to grease the ballscrew. It's Mobil SHC 460 I think.
And I have a new tube of SKF LGEP2/0.4 high load/extreme pressure grease
Can I use on of them for the spindle?
 








 
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