Colchester Student

  1. DeanH Member

    Messages:
    60
    Location:
    West Yorkshire
    I've always had an interest in machining but never given it a go - what better opportunity than to jump in at the deep end with the project lathe being sold by @fylde69. Helpfully he was able to help take it apart so that I could get it home by car and into the garage fairly easily using an engine crane. Here it is in it's temporary resting place (our knackered asbestos garage).

    [​IMG]

    I won't be able to use it in anger until we've finished a house refurb and built a replacement garage. For the time being I'm just going to get it back together, source the missing parts and make sure everything works.

    So far I've remembered how the various bits and pieces go back together but I'm stuck with re-fitting the apron and saddle. From what I can gather the lead screw and shaft underneath (not sure of the name, by all means teach me a lesson!) need to come off so that the apron can be offered up and slid on?

    [​IMG]

    I've undone two grub screws inside the gearbox on the lead screw (pictured above) and now have lateral movement in the lead screw but can't seem to get it to come loose. The problem seems to be the piece that the right hand grub screw goes into - it's not sliding down the shaft like the rest of the gears are.

    Is it the lead screw that is secured using the ball bearings? If so I believe we used a pair of water pump pliers at the tailstock end and a pry bar to get it out when taking apart. Tried that and the pliers just want to slide off.
     
    Anguz and daleyd like this.
  2. Agroshield Member

    Messages:
    928
    DeanH and daleyd like this.
  3. When I had the saddle and apron off mine I don't seem to remember going into the gearbox that time. Sure the lead and feed screws just separate at the clutches just to the right and outside of the gearbox. Just need to loosen them at tail stock end and slide to the right.
    Check the condition of the support bushes in the apron. Mine where well shot and part if reason for removing apron. Easier to replace them now than in future. 3/4 I'd oilite bushes I seem to remember for feed screws, think the lead screw is larger.
     
    DeanH likes this.
  4. DeanH Member

    Messages:
    60
    Location:
    West Yorkshire
    Yep that's on the list to do. The bed will get a coat of oil and wrapped in cling film as well. The garage leaks so the whole thing will have a tarp thrown over it to keep it as dry as possible.

    We definitely took the gearbox cover off when dismantling it. It may be that I'm just not getting a good enough grip when trying to apply force with the crowbar against the bed.
     
  5. Carl Wilson Member

    Messages:
    1,731
    Location:
    Moray
    Crowbar against the bed?! Wtf?!
     
  6. DeanH Member

    Messages:
    60
    Location:
    West Yorkshire
    ...end of the bed, not the ways. The face that the end of the lead screw comes through.
     
  7. fylde69 Member

    Messages:
    37
    Location:
    blackpool england
    the right hand arrowed part is a nut, needs unscrewing as you draw the (top)leadscrew out

    (bottom) feed shaft is levered from the right side of the machine (dont lose the clutch parts!!)

    craig
     
  8. Carl Wilson Member

    Messages:
    1,731
    Location:
    Moray
    Sorry, just about pooped my pants there.
     
  9. DeanH Member

    Messages:
    60
    Location:
    West Yorkshire
    I've literally just worked that out from watching this video...



    At 0:53 you can clearly see the threaded section where it goes through the nut you mention. Cheers!

    No problem at all, I'll be the first to say I don't know what I'm on about so I may not explain things as well as others would!

    EDIT: Slides straight out with the nut undone, easy when you know how!
     
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  10. DeanH Member

    Messages:
    60
    Location:
    West Yorkshire
    Next job will be motor and power...

    The lathe didn't come with a motor and is wired for three phase. I have done a bit of reading and the easiest way forward seems to be a VFD with a replacement three phase motor.

    Any advice on wherther these motors and VFD olderisbetter is selling would be suitable?

    https://www.mig-welding.co.uk/forum/threads/brook-3ph-2-pole-motors-and-vfd.98015/

    From what ive read the lathe would originally have had a 3hp motor, so 2.5kw seems about right? Frame size may be different but the plate can be drilled as long as it fits in the cabinet. My only concern is the RPM, brook motor 2800rpm vs original Colchester 1200rpm(?). Can I turn it down to 1200rpm on the VFD or will that cause problems?

    Any help appreciated!
     
  11. DeanH Member

    Messages:
    60
    Location:
    West Yorkshire
    @spencer 427 - could you shed any light? Concerned about how turning down by VFD may affect torque?
     
  12. mike os

    mike os just a little insane.....

    Messages:
    6,568
    Location:
    North Wales
    Get the correct speed, iirc it's a 1440rpm

    Power drops off as frequency drops, ideally you run at 50hz and use the vfd to tweak your speed
     
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  13. DeanH Member

    Messages:
    60
    Location:
    West Yorkshire
    Thank you, at least I know now.
     
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  14. DeanH Member

    Messages:
    60
    Location:
    West Yorkshire
    Another question, do I need to get a VFD to match the KW of the motor, or is the VFD's KW rating an upper limit? i.e. can I oversize the VFD if one comes up?
     
  15. mike os

    mike os just a little insane.....

    Messages:
    6,568
    Location:
    North Wales
    You can oversize a bit but vfd also has a lower limit too so a 10kw will probably not be happy
     
  16. DeanH Member

    Messages:
    60
    Location:
    West Yorkshire
    I now have a motor (3 phase (dual voltage), 3 horsepower, 1450RPM so fairly close to original spec?). It was on ebay for a very reasonable price and also seems to be brand new - the knockouts on the top box haven't been used.

    [​IMG]

    [​IMG]

    So the final piece of the puzzle is a VFD - I don't have loads to spend so will probably be going for a Chinese one. HuanYang seem to be a good choice from reading here. Before I go and waste my money can anyone confirm whether this model will work?

    https://www.ebay.co.uk/itm/New-3HP-...020628&hash=item4699cb20f0:g:5ssAAOSw8Kxd-c1R
     
  17. mike os

    mike os just a little insane.....

    Messages:
    6,568
    Location:
    North Wales
    That will be fine on spec, cant comment on the brand
     
  18. DeanH Member

    Messages:
    60
    Location:
    West Yorkshire
    Brilliant. I'll chance it on the brand, just wasn't sure on spec as the listings were all near enough identical. Easy to get confused!
     
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  19. mike os

    mike os just a little insane.....

    Messages:
    6,568
    Location:
    North Wales
    Its 240v in 3ph out and 3hp ... after that it's all about additional features
     
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  20. DeanH Member

    Messages:
    60
    Location:
    West Yorkshire
    Yes, took me a while to realise that the aim of the VFD was to convert single phase to three phase rather than step up the voltage too. All is clear now.... Hopefully!
     
    mike os likes this.
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