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    Default TOS sn40 b HELP

    I picked up a fairly clean sn40b the other day to replace my little 13" Colchester mk1.5 since I had outgrown it. I love the TOS so far but have run into a few problems that I can't find answers to and am hoping someone here with experience can help.

    First off is the 8:1 lever on the gearbox, both positions seem to produce a 1:1 ratio instead of the 8:1, I don't have an immediate need for it but it's just confusing me why both positions give me the same ratio, they both power the drive so it doesn't appear anything is broken.

    Next is a couple problems that might be related, first is a weird pattern when doing longitudinal cuts, appears to be harmonics almost like a long spiral pattern in the surface and I can't get a smooth finish no matter material, cutter, speed or feed. I checked the spindle bearings for play and they were tight, no detectable movement up and down using a block, bar and indicator and spindle runout didn't even register on the indicator. Gibs are tight and ways are nice and clean.

    Another thing I noticed is after running for a while, not doing heavy cuts either, there was a noticeable amount of oil coming out of the spindle.
    Is it possible the bearings are bad but still tight and causing this problem and is there a good way to tell?
    Headstock doesn't sound noisy to me.

    Last question, at least for now, is what is the proper procedure for maintenance of the oil filter? I'm planning on doing the fluids and want to clean the filter while it's drained.
    I have a manual I printed on scribd and it came with the manual with all the technical drawings, not sure if I'm missing a page or two or if there is a different manual I don't have because I can't find anything about fluids or adjustments in them.

    Thanks for any help
    Brad

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    My manual has chart with oil specs and also section on adjustment of spindle bearings. It also talks about the 8:1 ratio thing. I no longer have the lathe and don't really remember details of operation but if you want the manual let me know
    Bob

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    TooManyGT,
    The 8:1 ratio only comes in at the lower speed range, I think the lever at the top left is the one, slow range to the left, high range to the right.

    The TOS SN range have a spindle bearing arrangement where the front bearings take the radial load only, all the thrust is taken by angular contact bearings at the rear of the spindle. These need to be correctly adjusted, that is with preload.


    Ray
    Last edited by daredo222; 11-08-2014 at 01:58 PM. Reason: Didn't read byawor's post

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    The 8:1 lever, believe this function is defined in the feed chart/tag.

    Harmonic lines during longitudinal feed, check that live center. I rebuilt the live centers with new bearings and the harmonic feed lines stopped. One machinist in particular would run coolant near the live center and the fluid would run past the wiper and get to the bearings. These were Skoda centers. A good tool but a poor seal.

    The oil filter on the lathe had the plate style filter on the back of the headstock. Give it a turn now and again to peel off the debris.

    The oil level sight glass may be mounted on the back of the headstock, memory check here for so many lathes ago, so check the fill level. Too much oil and it could overwhelm the slinger on the spindle nose.
    Don't remember if this lathe had a wet sump. If yours does then the extra oil will stir up debris from the bottom. That chaff will be abrasive to gears and bearings.

    Is oil showing in the headstock sight glass? The electrician hooked ours up and nobody checked for proper rotation. The motor will still run in either direction but the pump was directional. When the motor direction is reversed the pump will not push oil to the bearings and to the sight glass.

    Does the thread dial unit have additional dial plates plus interchangeable gears at the bottom of the shaft? If yes, combinations of the dials and gears provide for the range of threads. The shops TOS was capable of using the thread dial for metric threading the same as for inch threads. ie; Spindle reverse was not used when threading metric.

    Open the door on the left of the headstock to expose the gears that drive the quick change. There was an idler gear mounted on a shaft. There was an oil point on the end of the shaft. When the gear is removed the cross drilled hole for oil was not present. The shaft is hardened but
    I was able to drill the cross hole for oil. The bore of the gear was bored out and sleeved with a bronze bushing.


    John
    Last edited by jhruska; 11-09-2014 at 12:04 PM. Reason: Sppelling

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    Thanks for the replies, I'll have to try the 8:1 lever in the low range once I finish the PM and clutch adjustment done.

    To answer a few of the things that were brought up:
    I tried with and without a center and still get the pattern, I also tried hand feeding with the carriage and compound with similar results so i'm pretty sure it's isolated to the headstock.

    As for the oil it's pumping to the headstock (visible in the sight glass) as for the level it was a little low (based on the nightshade on the clutch cover) it a was below the sight glass when I went to drain it but not sure if that was due to what I lost when running it so far.

    I assume the filter is the T- handle just below the clutch access, I can't get it to turn so i'm going to take it out and clean it while the sump is drained.

    Can anyone show me where the access is for the rear spindle bearing adjustment is? I read up on it a little on some old post but still not sure where it would be.

    And yes, my threading dial has 3 disc I believe and 2 gears, the previous owner had a bunch of new gears made for the apron since it apparently had a little case of coolant rot and while he was at it he also had new thread dial gears made out of bronze since apparently the originals were some sort of fiber gear.

    Thanks for the tip about that shaft not being drilled, I had read about that but wasn't sure which one it was until now, all the external gears appear to be in good shape.

    I'm pretty sure it has the wrong oil in the headstock, seems pretty thick, heavier then aw32 that's recommended, have a hard time getting the motor to start if the shop is below 55f, which shouldn't be a problem using a 10hp rotary phase converter.

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    "Can anyone show me where the access is for the rear spindle bearing adjustment is?"

    It's at the back of the headstock. The electrical panel can be swiveled out of the way & then you will see a cover plate. Assuming I haven't lost my memory - as you look into the headstock you will see two shaft nuts on the back end of the spindle. The first nut is a locknut, it is split & has a clamping screw, loosen this screw before attempting to undo the nut. The second nut, the one closest to the bearings, is the one that you actually do the adjustment with. I advise you to look at the manual re the proper adjustment.

    Ray

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    Ok, same setup as my old Colchester it sounds like, I'll search the manual again and see if I can find the info, if not hopefully I can find someone with a useful manual that can share the info. All the info I've found before this was dealing with the front bearings with the tapered seat. Glad to see they went simple for the rear.

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    When the shop got the 14" TOS I pulled the top cover. I think it was related to no oil in the sight glass. The machine had light use when we got it.
    The oil looked dark and thick. The gears looked great and tooling/grinding marks were still present. So I left the original oil in the headstock.
    Never got around to inspecting the quick change. Production forces needed a win. There seemed to be a noise during operation, sorta like an eccentric clunk. This was a machine marked CSSR, Soviet era.

    Way wipers for the cross slide were fashioned from Bridgeport knee/column wipers. The aluminum wiper covers are 55 degrees so with a little modification they fit quite nicely for the dovetails of the lathe.
    John

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    Well I finally had some time to work on the lathe, changed the oil and removed/ cleaned the filter so now I can turn it by hand in the future, I don't think it had been turned in a while.
    Checked the rear spindle bearing adjasustment, seemed a little loose so tightened it up, found the tip of a large flute extractor that had been cut off sitting in the little sump area for the return drain in the headstock, really odd. Also found what the scraping noise when I turned the Chuck backwards by hand was coming from, turned out to be a zip tie behind the outer ring on the spindle nose, once again odd.

    Got the clutches adjusted properly, had to center the clutch fork also as it was biased towards the fwd clutch.

    I'm still getting the cyclic pattern, it's hard to tell but I think I can feel a rumble when I spin the chuck by hand so I'm thinking new bearings might be in order, found a FAG sp bearing for the front at what seems a decent price, still trying to sort out the rear.

    Another problem I forgot about is running the higher speeds I.e. 1000-1400-2000 I have to baby the clutch to get it up to speed, acts like it wants to spin up and then slows back down and even tripped the breaker once, seems as though the spindle break is coming on, no problems in any other speeds and motor seems to have plenty of power, all three legs off the phase converter are within a couple volts and steady.
    I love this lathe but really need to get the surface finish better.

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    Can't help too much on the spindle as we no longer have the lathe. Think about heat and when to adjust the bearings. I'd rather do the adjustment when the headstock is warm. The front bearing should be held. Does that have a separate adjustment?
    Check the heaters for the slow spool-up breaker disconnect. Might have to turn them up.
    Pulled the motor on the TOS as the hz was different. Put a 7 1/2 hp motor in for 60 hz.
    John

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    "Another problem I forgot about is running the higher speeds I.e. 1000-1400-2000 I have to baby the clutch to get it up to speed, acts like it wants to spin up and then slows back down and even tripped the breaker once,"

    Sounds like you have over-adjusted the clutch. Also, and this is just a personal preference, I always used my TOS SN's on the slow range, maximum speed 1000. I'm talking about the two gears that you swap over, in the cast iron housing inside the cover over the change wheels.

    Ray

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    It did this before the clutch adjustment, I changed it over to the high speed the other day to try some small dia work with the collet setup.

    I adjusted the clutches based on all the information I found in the manual and online and a little by "feel" once I got it close to dialed in. Any less and it seemed to have excessive slip (15+sec spoolup time without load to the higher speeds).

    Any suggestions on on the clutch adjustment? It seems happy other then the top speeds, I don't use them much but want to make sure it's right when I do need them. It actually speeds up at first then sounds like something is pulling it back down.

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    Depends on the size of the lathe, chuck, and if a large job is in the lathe. ie; how much mass has to be put in motion.
    Three second spool-up is too long. Slippage burns the clutch plates. I usually adjusted lathes for around two seconds for most of the low to mid range speeds. Allow more time for the highest speeds. And for those I use the clutch to bring it up to 70% and then snap it in.

    The clutch(s) will be too tight if engagement takes more effort than when the clutch plates are loose.
    Manufacturers would stipulate a clearance setting measured with feeler gages, .004, .008, .012 thousands.
    If the spindle is stiff to rotate when engaged in high gear while the machine is off the clutch may be too tight.
    If the spindle rotates or pulses when the throw is not engaged, and the motor is on with gears engaged the clutch may be too tight.

    A long spool up time means the clutch plates are not compressed together. They are rubbing together and will overheat, burn, and crack. There may be super heated oil vapor leaking out of the spindle area. The clutch is too loose.

    Most modern machines use a wet clutch. Those that have a dry sump will have jets of oil directed at the clutch plates. It is important that this oil source is not misdirected.
    Did you look at the heaters in the electrical panel? What does the motor name plate say?
    John

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    Thanks for the tips, I know it was slipping way to much, I was shooting for at least 3sec startup with the 10" 3 jaw no workpiec. under that for all but the thethree highighest speeds. I feel confident the clutch is right. I thought had experience with this particular model and was just wondering about any particularities with it.

    I have a couple more things to check but its looking like I'll be doing spindle bearings on this in the near future, I believe I've found the right sp bearings but will probably post up the pn's just to make sure I'm not missing anything

    If anyone here has done these bearings before I'd love to get any tips or tricks to look out for.

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    I am I dire need of a manual for a sn40b lathe.thanks gimpy

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    I have a photo copy you can have for the cost of copying 60 pages, email me if you want it [email protected]

    Bob

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    Hello Bob,

    I'm interested in to the TOS SN40 manual. Do you still have it?


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