Harrison M300 Saddle locked

  1. Regor

    Regor New Member

    Messages:
    11
    Location:
    Swindon, Wiltshire, England
    This morning when traversing the saddle I heard a ticking noise, as it did not affect any of the lathes functions I ignored it, then when running a facing cut I noticed that I could not drop the feed leaver, the only leaver on the apron that i could move was the power switch leaver so with the late stationary I have now discovered that the half nut leaver is locked solid the feed travers direction plunger is also locked, and of course as feed is engaged I can now no longer travers the saddle, I am guessing that something has come adrift in the apron but a clue as what to look for would be very helpful
     
    Last edited: Aug 1, 2020
  2. Hopefuldave Intergalactic pot-mender

    Messages:
    1,598
    Location:
    The Shed of Danger, surrey, England
    Not sure about Harrisons, but on my Holbrook there's a sliding plate that interlocks the half-nuts and the feed latches, if it jams half-way neither will move (as I found out...)
    It has a peg at one end which goes into a cam face groove onthe half-nut operating shaft, notches that allow the feed assemblies to move when nuts disengaged but hold the plate in position so the halfnuts can't be engaged - easier to see it than explain it!

    I'd have a look for something similar (in function) could be a plunger, plate that slides, relief on a shaft to allow movement past it...

    Dave H. (the other one)
     
    mtt.tr likes this.
  3. Brad93

    Brad93 M J B Engineering

    Messages:
    8,519
    Location:
    Essex
    Harrisons have a device that stops you from engaging the half nuts if you’ve got the feed screw engaged.

    sounds like something has come adrift inside the apron and locked the two gear trains up.

    Leave all the saddle in position, you’ll probably have to remove the feed screw, leadscrew Etc, then drop the apron.

    once you’ve freed the leadscrew off at the tailstock end of the lathe you should be able to screw it out.
     
  4. Regor

    Regor New Member

    Messages:
    11
    Location:
    Swindon, Wiltshire, England
    Thank you both Dave for your intergalatic message, and Brad, late last night i found i could move the saddle although it is very stiff, but the cross slide,feed leaver and half nut leaver are all still solid.
    i am at a disadvantage that removal of the feed ans lead screw is not possible due to the proximity of one of the workshop walls, but i may be able to remove the apron with feed and screw barsin one
    i will post some pictures as soon as possible
     
  5. Shox Dr

    Shox Dr Chief Engineer to Carlos Fandango

    Messages:
    15,287
    Location:
    East Yorkshire
    The power fed handle is screwed in. If its not set correctly it can lockup. Loosen the handle and see if it frees up
     
  6. Brad93

    Brad93 M J B Engineering

    Messages:
    8,519
    Location:
    Essex
    I tell you now, if it’s anything like removing the apron on a Harrison 140, it’s not possible with the feed screw and lead screw in place. The plain bearing at the tailstock end is dowelled in place, and the apron drops down.

    If you try and force it you risk bending your leadscrew.

    Do the job properly would be my suggestion.
     
    Shox Dr likes this.
  7. Seadog

    Seadog Forum Supporter

    Messages:
    6,301
    Location:
    NE London - UK
    There's a lesson to be learned about leaving adequate room around machines for dismantling and servicing.
     
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  8. Brad93

    Brad93 M J B Engineering

    Messages:
    8,519
    Location:
    Essex
    That’s why mine is a good foot off the wall so you can squeeze round the back.
     
    Hopefuldave likes this.
  9. daedalusminos Member

    Messages:
    861
    Location:
    Norwich
    You *could* remove the apron with both leadscrew and power shaft in place but considering it's tricky (and heavy) manoeuvring the apron out with them clear then not advised.
    If there is no other option then propping the apron and removing the saddle would give more access.
     
    Hopefuldave likes this.
  10. Shox Dr

    Shox Dr Chief Engineer to Carlos Fandango

    Messages:
    15,287
    Location:
    East Yorkshire
    Apron will come off with l/s and p/feed still fitted but needs to slide out of the clutches on the g/box. Need about 2".

    total ball Ache though
     
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  11. Regor

    Regor New Member

    Messages:
    11
    Location:
    Swindon, Wiltshire, England
    Well i have now located the problem the cross slide gib jumped past the adjustingscrew at the rear of the cross slide and is now jammed solid.
    The removal of the feed and leadscrew is tricky inany situation and unless the feed gearbox is removed first then the only option is to gently ease off the support bracket past the dowles and slide it off. NOT THE BEST APPROACH i know. but i needed to get into the workings fast and checking with a stright edge all is well (phew!!)

    So all i have to do now is to tap out the brokn Gib strip and see what else has broken

    [​IMG] [​IMG] [​IMG]
     
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  12. Regor

    Regor New Member

    Messages:
    11
    Location:
    Swindon, Wiltshire, England
    Before you condem me for bodgery ask the previous owner why the gib strip was cut
     
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  13. daedalusminos Member

    Messages:
    861
    Location:
    Norwich
    Good news, new gib strips available from 600 group.
    Bad news, £143 ea!
     
  14. Regor

    Regor New Member

    Messages:
    11
    Location:
    Swindon, Wiltshire, England
    £143, umm well not as bad as i thought, but when you tot up the hours involved in reproducing one to the same tolerances with the same material it is a snip.
     
  15. Shox Dr

    Shox Dr Chief Engineer to Carlos Fandango

    Messages:
    15,287
    Location:
    East Yorkshire
    Why wouldnt the saddle traverse then?
     
  16. Matthew Tinker Member

    Messages:
    43
    Location:
    93300 Aubervilliers France
    Silver solder?
     
  17. Regor

    Regor New Member

    Messages:
    11
    Location:
    Swindon, Wiltshire, England
    Well Shox Dr, i can only assumethat when the cross slide sized the tortion on the rest of the gearing in the apron was suficiant to make traversing very stiff which it was, as there does not seem to be anything wrong in the apron.
     
  18. Regor

    Regor New Member

    Messages:
    11
    Location:
    Swindon, Wiltshire, England
    Matthew Tinker, silver solder??? dunno it is worth a try !!
     
  19. northwest

    northwest Member

    Messages:
    1,490
    Location:
    Manchester UK
    You do not really need the full length of the gib strip for it to be functional, weld the bits back on and make sure they do not foul the dovetails, all sorted.
     
    rory1 and Regor like this.
  20. Regor

    Regor New Member

    Messages:
    11
    Location:
    Swindon, Wiltshire, England
    I have now also identified the source of the ticking noise please see this vid
    https://youtu.be/HP6gBM5-UaE
    I think it is being caused by the red circled gear as the tick is before one full revolution of the 152 tooth gear, but why would it only tick in one direction.
    is this somthing i should be concerned about??
     
    • apron gears.jpg
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