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Schaublin 135 rebuilding project- ongoing thread

avivz

Cast Iron
Joined
Jan 28, 2009
Location
Israel
I will use this thread to document the rebuilding process of my new-old Schaublin 135 lathe.

Some background here: https://practicalmachinist.com/forum/threads/advice-on-potential-schaublin-135-purchase.419001/

Starting yesterday, I was focused on taking out the variator and the (seized) motor. It took me "only" a full day .
As the entire drive is stuck, it was not possible to take out the belts by rotating the pulleys in the normal manner one would do it. The first task was to release the tension on the belts, supporting the motor with some wood blocks and take out the variator pulley shaft. To take the variator shaft out, there is a cap on the inner end of the shaft (#6 in the picture), with two Allen cap screws. After taking out the cap, there is a circlip on the shaft. Taking them out was a long task, as I had to reach to the inner end with my hands, and use a mirror... after the circlip was out there was no room to tap out the shaft, so I had to improvise some puller and pull it with a bolt.
Then the next trouble was the shaft of the variator yoke. The shaft sits inside what seems to be some kind of a rubber bushing (#3). The shaft was completely stuck in that rubber and again, no access to tap it out from the inner end. After releasing the set screws of the two collars (one on each end), there is a bore with M6 internal thread on the outer end of the shaft, but it was not strong enough to pull out the shaft. I used some manual work and a drill to crumble the rubber bushing and then I could pull the shaft and take out the yoke.
Next, supporting the motor to the right height, releasing the 4 bolts that connect the motor to its yoke and slide it out on a wood platform.
Disassembling the fan cover, I could see it was already serviced before (to a low quality), two fins of the fan are broken and missing. A suspected, the brake assembly had a catastrophic failure with many of its parts got shredded. It seems the failure began with the bolts that fasten the brake to the motor. I guess they either got loose and/or sheared off.



Regarding the spindle- I started to disassemble the upper covers, including the detail panel and the access cover to the feed gearbox. Including the gear shifter on the upper part of the headstock. I didn’t have the time to further investigate, however I notices something that I didn’t notice before- when I rock the spindle (few degrees) back and forth, there is a light feeling of magnet. Means that when I reverse the direction, It feels like I have to overcome a very light magnet before the spindle moves to the other side, where again a light magnet snaps it into place. As far as I could see, there are no electrical cables going into the headstock (excluding the gear shifter lock solenoid), so maybe I missed it but any chance there is any sort of magnetic lock inside the headstock?
Any other ideas before taking out the feed gearbox and open up the headstock?

Some forethoughts:
1. Considering its high cost, do I really need a brake? What it’s good for?
2. There were no hyraulic lines connected to the variator. I assume it's the dry version?

Any constructive feedback is welcome.
 

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Hi well done for getting started, hope the spindle outcome is not anything major.

Yes you have the later yoke for the Variator system, that in itself is a real bonus as this yoke part alone from Schaublin is over 1000SF!!!!

Regards the brake, nice to have it but not the end of the world if its past economical repair, if you are thread cutting a lot then its of big use but otherwise not. I think the parts for the brake assembly are available, the bolts, springs etc, I remade the bushes in bronze as the plastic ones were worn so have the dimensions of the bushes if you need to get some made. Your friction housing and disc can be machined, I did mine, just check the windings in the electromagnet still work otherwise its a pointless task!

Regards your PM sadly the 'missippi' guy I came across simply via the internet, never spoken to him so don't have any contact details for him.
 
Next episode 13.1.24:
I pulled out the main gearbox and the headstock upper half. Everything inside looks clean and no hard evident to any “accident”. All gears spin nice and smoothly. The input gear to the headstock spins freely (rotates around the spindle on the left upper part). Same as for the counter shaft in the headstock (lower part). The right upper gear seems to always rotate together with the spindle, but can move axially to change the backgear. The unfortunate only explanation I have is that the spindle itself is locked by its bearings.

Next phase would to take out the spindle. With the explanations from Marc’s thread I will take out the collet closer boss from the spindle end and then open the end flange and the first lock nut, which in my understanding should allow talking the spindle out towards the front end. If anyone has guide/tips on the spindle removal, it would be highly appreciated.
 

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Avivz! On december 10 I posted a link to my document collection for the 135. Did you get it? On page 31-33 in the manual "Schaublin 135 servicehåndbok_sec_vat" there is a detailed description on how to take your spindle apart, and to adjust the plays. You will need a dial gauge indicating 0,001mm, and be prepared to understand the calculations mentioned before you start. Follow the instructions carefully, the bearings are rather delicate when taken apart. They can be adjusted for endplay as well as radial play, just follow the instructions carefully. Take care to reassemble the spindle with the lines on the bearing's circumference in the correct positions as stated. Clean out the bearing seatings as well as the lubrication tubes and conduits, and the oil pump and reservoir including the filter/ sieve before reassembly. If you find the procedure too challenging, try to find out if you can remedy the binding in the spindle without dismantling it completely. Good luck, take your time, and ask when in doubt.
Ole
 
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Avivz! On december 10 I posted a link to my document collection for the 135. Did you get it? On page 31-33 in the manual "Schaublin 135 servicehåndbok_sec_vat" there is a detailed description on how to take your spindle apart, and to adjust the plays. You will need a dial gauge indicating 0,001mm, and be prepared to understand the calculations mentioned before you start. Follow the instructions carefully, the bearings are rather delicate when taken apart. They can be adjusted for endplay as well as radial play, just follow the instructions carefully. Take care to reassemble the spindle with the lines on the bearing's circumference in the correct positions as stated. Clean out the bearing seatings as well as the lubrication tubes and conduits, and the oil pump and reservoir including the filter/ sieve before reassembly. If you find the procedure too challenging, try to find out if you can remedy the binding in the spindle without dismantling it completely. Good luck, take your time, and ask when in doubt.
Ole
Hi Ole,

Yes, I got all your info. Thanks! First I have to take out the spindle and then we’ll see what’s the deal. The redial and axial play adjustment procedures depend on measurements taken before disassembly of the spindle. However, as the spindle is binding as in my case, I’m not sure it will be useful. First things first, let me take the spindle out and solve the mystery…
Ole, in the other thread, you mentioned there are two variants of the spindle bearing setup. Could you please elaborate on these differences and reference the relevant diagrams?
 
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Avivz!
Yes, the bearing arrangement was redesigned around 1972-3 or something (the drawings are from november -71) . Your lathe has two- row cylindrical roller bearings, and angle- contact ball bearings for axial control behind the rollers. My later (1974 model) has a redesigned spindle with a 3-row angle contact ball bearing in the front, doing both radial and axial control. The bearings on the left side are also different.

1705321357303.png
 
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PS, Avivz! Try to find out if the spindle is not binding because you have removed the speed change mechanism from the back of the spindle head, and possible locked up the spindle in the process - ?
 
PS, Avivz! Try to find out if the spindle is not binding because you have removed the speed change mechanism from the back of the spindle head, and possible locked up the spindle in the process - ?
Thanks for the explanation. Yes, with everything removed around the headstock I can check the headstock gear as you can see them from the front side (where the gearbox is attached). While moving the gear shifting forks on the back side of the headstock, I can manipulate the headstock gearbox as I need.

On the spindle there are two gears. The left one is the input gear, which freely rotates around the spindle, driven by the drive belt. This gear indeed spins freely when I put the shift selector in the neutral position. On the top right side, there is another gear which rides on the spindle. This gear always spins together with the spindle, but can move axially in order to engage with the counter-shaft gears (below the spindle shaft). So when in neutral position, both the input gear and the counter shaft can spins freely. I don't see any issue with these gears,

Another quite weird (to me) is the feeling of the spindle while I move it back and fourth. Within the small limits that it does spin, the feeling is unusual in a way that I cannot interpret what it could be- it's like at each side of the stop there is a magnet which pulls the spindle to an indexed position. When you move to the other end, you cannot stop in the middle of the two stops, as the spindle immediately jumps to the other end. The closest feeling I'm familiar with is from permanent-magnet motors. Maybe a over-loaded bearing would feel similar, jumping-like movement, but I really have no idea, so we will have to wait until I manage to take the spindle out.

Aviv.
 
Aviv! Do you think that the lathe may have been out of use for several years? The strange resistance when you turn the spindle may be from gelled-up oil in the main spindle bearings, or other "dirt" in the bearings. The play in the bearings is very small (less than 1/1000 mm), and so is the tolerance for foreign matter. Try to wash with kerosene or similar supplied through the lubrication openings visible on the white- painted gallery in the top face of the spindle housing. Use a syringe or similar. Turn the spindle back and forth in the process. Maybe it will loosen up a little. If so, continue with patience. Maybe leave it overnight with solvent.
Ole
 
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Going forward, as I had to accept the issue comes from one of the bearings I decided to take out the spindle. Unfortunately, it found out that the front double row cylindrical bearing is seized. Next step is to take out the angular contact bearing and try to understand if/how big is the damage the bearing.

The manual says SKF NN 3014 K/SP. Searching SKF website, I can find NN 3014 KTN/SP - is it the modern equivalent PN?

In any case, this is $$$ bearing and I'm not sure how to proceed. Even if I decide to invest, who promise me the other bearings are up to spec and the spindle itself is not damaged (beyond visual inspection). As the front flange is very close to the bearing, I'm not sure if it can be extracted w/o damaging it. What would you do?

In any case, as Ole suggested, if no visual damage to the bearing can be seen in place, I will soak it in kerosne and cross my fingers. Any other ideas?

Beyond that, the rear bearing outer race shows some marks, maye surface rust or galling, but does not seem to be indented in a first touch.

As I wrote in my previous post, the headstock pivoting ping was interfering with the front flange, so I had to push it against the spindle with the bolt in order to extract it few milimeters. No access with a press from above.
 

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Recalling the details from yesterday, I recalled that when the spindle came out, there was barely oil coming out of the front compartment. The spindle came out almost dry, for sure not full with oil as the gear box or as I would expect. I suspect the spindle went out of oil, which means all bearings will have to be replaced? 😣

BTW- does few days of soaking in kerosene/diesel fuel can damage the polymer cage of the bearings?
 
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That kind of corrosion means it was dry, condensate moisture likely made it "sweat" by not being in a temp-humidity controlled environment, water goes to the bottom and rusts the rollers to the race. All bearings should be replaced if you are trying to achieve any kind of tight tolerance or longevity. Sometime that style thrust bearing is expensive and hard to find, but a few companies make drop in replacements using 2 angular contact thrust bearings.
 
That kind of corrosion means it was dry, condensate moisture likely made it "sweat" by not being in a temp-humidity controlled environment, water goes to the bottom and rusts the rollers to the race. All bearings should be replaced if you are trying to achieve any kind of tight tolerance or longevity. Sometime that style thrust bearing is expensive and hard to find, but a few companies make drop in replacements using 2 angular contact thrust bearings.
Makes sense. Any recommendation to such a drop-in replacement? The manual says the front double row cylindrical bearing is
SKF NN 3014 K/SP
 
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So its a tapered bore double row roller, should be very available. My recommendation is to stay with quality bearing manufacturers, from reputable dealers, lots of counterfeit garbage on the market currently. Skf nsk ntn barden timken ********* etc should be fine-in no particular order. Expect to pay for these bearings, I expect your total bearing cost to be in the neighborhood of $1500-2k, with the thrust (ball) bearings likely being more than the roller. If you are tackling this yourself brush up on how to set preload on a tapered roller, you dont want to destroy your new expensive bearing.
 
The bearing to the left, double row angular contact (?) bearing is designated in the manual “SKF 234 414 / SP”. I could not locate this PN. any idea?
 
So thats a bit of a special bearing, but a few manufacturers still support them. Here it is in the skf catalog, its a real part number, should be a shelf item at your distributor of choice. As with any spindle bearing, there is some skill to installing these correctly so dont take that lightly. If you still cant find them feel free to PM me and I can probably point you in the right direction.
 

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Aviv!
Well, so far so good. Whether the (rust?) marks in the left race outer ring are too deep to be acceptable remains to be seen. The important thing now is to get the front bearings apart to find out why they are stuck, and how they are. To clear up a few things: 1. The lack of oil may well be due to the lathe having been left for years. Don't worry until you have seen and evaluated possible damage. 2. The bearings are not conical roller bearings, but cylindrical. The cone is inside the inner ring, stretching the inner ring to take up radial play when you tighten the nut. Do as I said, read the instruction in the manual, and be sure you understand it, before you proceed. Ask me if you don't understand. Download a full catalog from SKF, it explains what the different letters in the bearing name refers to. It is not possible to replace the bearings with different alternatives, but it may be possible to get the right bearing from a cheaper source. You either go with what you have, or replace the bearings with the correct type. But first, soak and rinse, see if the bearings do not loosen up.
To remove the bearings to the right, you first must remove the nut holding the bearings in place. This nut is locked with two small inhex screws that need to be loosened. Good luck!
1705614854469.png
(Picture c/o Rüdiger Krämer)
Ole
 
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Mind those tiny lock nuts with an even more tiny hex as they are often tight and a badly fitting or worn hex key will make mincemeat of the heads - use a new key or grind one down a few mm to freshen it up taking care not to soften it too....
 
Thanks for the good hints. Here are some pictures from today. The inner race of the angular contact thrust bearing as well as the cylindric front bearing did not come out easily. I had to heat them up and press the spindle out from the rear end against the front flange. I don’t like pressing out w/o driving both the inner and outer races together if the bearings might be re-used, but there was no other option.
The seized bearing is very dirty and shows a lot of galling marks. However I did not have the time today to open it up, give it a decent clean and take some pictures. Will do that tomorrow. From a very first impression, likely it will need to be replaced. The thrust bearing looks fine.
 

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