Standard Modern 11" Series 2000 Lathe Spindle Issue

[Crosche]

Hey all,

I set up an indicator on a piece of 1 1/2" stock that I was turning and found that it had a high spot that became more pronounced the further out I measured. This lead me to pull off the chuck and measure the spindle nose, which when I did I found a high spot of 0.0005". So, at this point I am at a bit of a loss as to how to correct the problem. I am not sure if I should adjust the spindle bearings or if the spindle is buggered or if it is the D1 collar that is attached to the spindle. Any of you guys with Standard Modern lathes have any suggestions?

Thanks,

Chad

 

[RobinHood]

Hi Chad,

so you were basically turning an “egg shaped” part?

did the high spot on your work match the high spot you measured on the spindle nose? if that were the case, I would look at the bearings. also check the spindle for a bend.

a straight spindle running true in its bearings should give you round work even if the nose had runout.

i believe the D-1 collar is integral to the spindle. at least it is on my SM1120, SM1340 and the Colchester. it looks on my lathes that the noses were cylindrically ground after hardening. I can’t measure any appreciable runout.

 

[Crosche]

Hi Chad,

so you were basically turning an “egg shaped” part?

did the high spot on your work match the high spot you measured on the spindle nose? if that were the case, I would look at the bearings. also check the spindle for a bend.

a straight spindle running true in its bearings should give you round work even if the nose had runout.

i believe the D-1 collar is integral to the spindle. at least it is on my SM1120, SM1340 and the Colchester. it looks on my lathes that the noses were cylindrically ground after hardening. I can’t measure any appreciable runout.

The lathe came from a high school and you can tell that it's seen some crashes. I suspect that it maybe more than a single issue and that my problems could be both the spindle or spindle bearings and the chuck as well.
Is it possible for bearings to cause a high spot at a single, repeatable location on the spindle? The owner's manual says that the spindle bearings can be adjusted, but I am not sure if that's somewhere I want to go right now since I could possibly make things worse.
Any suggestions on how I can check the spindle for straightness?
In answer to your question, yes, I believe that the part is slightly out of round.

 

[Tom Kitta]

I would re-measure everything and make sure the part is indeed out of round and by how much.

Are you sure its out of round not a taper?

See here: https://www.practicalmachinist.com/vb/cnc-machining/parts-out-round-why-185163/

 

[RobinHood]

What Tom said: re-measure your part as best as you can to make sure it is not just a taper. Also, if your chuck has worn (bell mouthed) jaws you may have the part move while you turn it - resulting it the observed problem. One way to see if it gets better would be to use the tailstock with a center to help support the part in the chuck - even if you have little stick out. If your out of round goes away, you need to regrind your chuck jaws. ( I had to do that on a cheap import chuck; it worked so well that I have since reground all 3Js - huge difference, well worth the effort ).

Any suggestions on how I can check the spindle for straightness?

As far as I know, the only accurate way to check for bends is to remove the spindle from the headstock. Use a surface plate and known good v-blocks to support the spindle on the bearing journals and a tenths indicator to check for runout while you slowly turn it in the v-blocks by hand.

You can use the same principle to measure for high spots (out of round) on your part that you made.

 

[RobinHood]

Is it possible for bearings to cause a high spot at a single, repeatable location on the spindle?

I suppose it is possible. Does the spindle turn nice and freely when rotated by hand? Especially check FWD/REV and feel for any binding as the rollers reverse in their races.

Have you pulled the cover off? Check for proper oil lubrication to the front bearing by the brass wiper arm. How? Put the lathe in neutral gear not with the RH speed selector as usual, but rather with the LH lever by moving it between two gears. You can see if you are between the gears by checking the rear shaft. Select the HI range on the RH lever and turn the spindle by hand. You want to see the bull gear pick up oil and the scraper “peel” it off and it should then flow through the port into the front bearing housing. That should happen in both spindle directions. Some of the oil scrapers are not adjusted correctly and do not direct enough oil into the main bearing, causing it to overheat. This eventually causes the binding described above.

You can also check the rear spindle bearing. If it is bad, you could get a rough running spindle and possibly the runout you have observed.

 

[Crosche]

So here is where I got to tonight. I put my indicator inside the spindle bore and didn't find any significant movement, although I don't have a tenths indicator so I am not sure that my measurement was relevant. The spindle seems to turn smoothly and I can't feel any binding.


Next I put the indicator on the face of the spindle and rotated it. At the #1 cam lock position I consistently read 0.001" low, so now I am worried since I don't know how a bearing could influence the spindle in only one place. Although, I did place a screwdriver in the gap between the spindle and the headstock and pried VERY gently and the 0.001" would disappear. As the photos show, the spindle is pretty beefy, so it seems unlikely that I was deflecting the spindle?

At this point I feel like I have to decide between the following:
1) try adjusting the main bearing
2) replace the main bearing
3) use my 4 jaw chuck exclusively
4) try to skim cut the spindle mount face (yikes!)
5) replace the spindle (YIKES!!!)

I did not try any tests with the 3 Jaw chuck since I do not trust it. The cam lock studs are worn and damage and until they are replaced I do not see value in performing tests with a suspect piece of equipment. Does this make sound logic or am I missing something? Tomorrow night I will take the cover off the headstock and see if anything seems amiss.

Any insight that you guys can share is appreciated because I am a bit out of my depth on this.

Thanks,

Chad

 

[John Conroy]

I think you are measuring the run out in the wrong place if you are concerned about it affecting chuck runout. If you look at the back of the chuck you will see that it registers on the outside taper of the spindle, not the inside where the pic shows the measurement being read. The face of the spindle does not have to be dead flat, the main interface between the chuck and spindle is the outside taper of the spindle.
Try measuring the OD of the spindle nose to see if any runout is in the same position as what you measured on the MT taper on the ID of the spindle.

 

[Dabbler]

@John Conroy Are you meaning the face of the spindle adjacent to the spindle nose (the discoloured part in 20200331_171531.jpg, above. It seems that a very light stoning of the entire face is in order. @Crosche notice the slightly raised area in 20200331_171629.jpg. that would be the face seat, and is the face contact area. A very light stoning of the seat on the chuck looks like it would do some good....

--- what I mean by 'light stoning", is to take a FLAT stone, and lightly pass it to feel for any burrs or imperfections. You won't find them with a test indicator. I use the following stone for this, which has been straightened by hand on a diamond hone.

 

[Crosche]

I think you are measuring the run out in the wrong place if you are concerned about it affecting chuck runout. If you look at the back of the chuck you will see that it registers on the outside taper of the spindle, not the inside where the pic shows the measurement being read. The face of the spindle does not have to be dead flat, the main interface between the chuck and spindle is the outside taper of the spindle.
Try measuring the OD of the spindle nose to see if any runout is in the same position as what you measured on the MT taper on the ID of the spindle.

Hi John,

The nose or cone of the spindle is what I measured initially. From my tests, the nose moved approximately 0.0005" and it seemed to always be in the same location. I will take another reading tonight and report my findings.

 

[YotaBota]

I'm going to guess the lathe is new to you. Did you download the operators manual from the SM website? It will show you all the parts and pieces and an idea of how they go together. Have you changed the oil in the headstock?, coming from a school it could have been well or not maintained. It may sound unlikely but I've read were noises bumps and grinds disappear after a flushing and oil change.

Don't be afraid of taking the lathe apart, it will give you a better understanding of how things work and how to protect it form damage in the future. I bought a SM9" that was in a school and have had it apart a few times to change parts. You really have to watch for grub screws that are installed from the bottom, under a cover or just hidden from grime. The spindle is about the only thing I have come across that you may need to "persuade", having said that my experience is with my SM9", Logan 400 and an Atlas 618 so we really need someone with first hand experience with your lathe. I just did a quick google and there isn't much out so take it slow and keep asking when you get stuck.

 

[RobinHood]

Hi Chad, good advice from both Johns.

The nose or cone of the spindle is what I measured initially. From my tests, the nose moved approximately 0.0005" and it seemed to always be in the same location

That could mean that the actual mounting flange (nose) of the spindle has taken a pretty big bump. The mashed up cam lock stud (circled in red) could mean that the chuck came off the spindle at one time pretty violently.



This is the area Dabbler was suggesting to stone off any burrs. Also check the mating surface inside your chuck body and lightly stone it. You can also run a stone on the face of the spindle to knock off any burrs.



When you attach the chuck, be sure to confirm the cam indicator line ends up between the 3 to 6 o’clock position as shown. If it is outside, you need to adjust the studs in the chuck(s).



1) There should be no spindle endplay; the 1 thou you measured is too much. Adjust the front bearing as per the SM manual - it gives the correct pre-load on the Timken bearing.

2) Replacing the main bearing could be a challenge as on later model lathes they shrunk fit the bull gear bushing onto the spindle. No way to get it off other than cut it. (Heat won’t do it, I tried - at least the amount I was willing to put in did nothing; perhaps I was too chicken?). Then you can get the Timkens off. Bearings are in the $1200 range - 6 months lead time from Timken.

3) If the spindle is not bent between the bearings, using any chuck or even collets in the spindle should give you round parts.

4) Not unless you know for sure where the problem lies. Then I would use a Tool Post Grinder. Or take the spindle out and have it cylindrically reground.

5) New spindle - going to be tough to find one and probably lots of $$$s.

 

[Dabbler]

+1 to wwhat @RobinHood said. Are you in Calgary? I could bring my Mit tenths and my Noga arm and we could remeasure everything.... [Respecting social distancing, of course]

 

[Crosche]

Hi Chad, good advice from both Johns.



That could mean that the actual mounting flange (nose) of the spindle has taken a pretty big bump. The mashed up cam lock stud (circled in red) could mean that the chuck came off the spindle at one time pretty violently.

View attachment 8360

This is the area Dabbler was suggesting to stone off any burrs. Also check the mating surface inside your chuck body and lightly stone it. You can also run a stone on the face of the spindle to knock off any burrs.

View attachment 8361

When you attach the chuck, be sure to confirm the cam indicator line ends up between the 3 to 6 o’clock position as shown. If it is outside, you need to adjust the studs in the chuck(s).

View attachment 8362

1) There should be no spindle endplay; the 1 thou you measured is too much. Adjust the front bearing as per the SM manual - it gives the correct pre-load on the Timken bearing.

2) Replacing the main bearing could be a challenge as on later model lathes they shrunk fit the bull gear bushing onto the spindle. No way to get it off other than cut it. (Heat won’t do it, I tried - at least the amount I was willing to put in did nothing; perhaps I was too chicken?). Then you can get the Timkens off. Bearings are in the $1200 range - 6 months lead time from Timken.

3) If the spindle is not bent between the bearings, using any chuck or even collets in the spindle should give you round parts.

4) Not unless you know for sure where the problem lies. Then I would use a Tool Post Grinder. Or take the spindle out and have it cylindrically reground.

5) New spindle - going to be tough to find one and probably lots of $$$s.

Yes, I am quite worried that the spindle has taken "quite" a bump and the 0.001" endplay from light pressure with a screwdriver is concerning too. I would think that the side load from cutting would be greater than the force I generated.
My manual doesn't have the torque settings or procedure to do it; however the SM 1120 & 1340 manual gives the torque value, so I will use that as a starting point.
For peace of mind I got a quote for the main bearing assembly; 2 V-cones and a cup; and was quoted $256 + GST. I may purchase the new bearing, but will have to see what I am dealing with once I take the cover off of the headstock tonight.

 

[Tom Kitta]

At least price for the whole assembly is not high and you can buy it!

 

[Crosche]

+1 to wwhat @RobinHood said. Are you in Calgary? I could bring my Mit tenths and my Noga arm and we could remeasure everything.... [Respecting social distancing, of course]

Yes, I am in Calgary. I live in Huntington Hills area and I would appreciate the help and a second set of eyes. I believe my shop is large enough to meet the current social distancing requirements and can supply your preferred choice of beverage. Please let me know what your availability is like and we can set a time up.

Regards,

Chad

 

[RobinHood]

For peace of mind I got a quote for the main bearing assembly; 2 V-cones and a cup; and was quoted $256 + GST.

Are you sure the quote was for ABEC 7 or better high precision bearings? If it is, perhaps you could share the vendor with the group, thanks.

 

[Crosche]

Are you sure the quote was for ABEC 7 or better high precision bearings? If it is, perhaps you could share the vendor with the group, thanks.

The quote was for the following as specified by my owner's manual:

Timken type T.D.O. Assy. No. A-4968
Consisting of:
Qty 2 x cone, 387A
Qty 1 x cup, 384ED

 

[RobinHood]

Sorry Chad, but I am pretty sure that was a quote for standard precision C3 clearance cones and cup like they would use in an automotive or general industrial application.

You need #3 precision (or better) for your lathe:




$1534.21 + GST and they are available to order only; when I checked ~ 2 years ago, it was about 5-6 months...

You might get a discount if you can put it through a company name.

 

[Brent H]

Hello.

Do not forget the back bearing in these lathes. It is a a normal roller hearing and typically wears out before the front conical ones. The adjusting nut for the forward conical bearing preload rides on the centre of this bearing. Could be that This bearing is worn and messing up the preload by the. 0.001”. Could cause a few other issues...: