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  1. #1
    m_c's Avatar
    Lives in East Lothian, United Kingdom. Last Activity: 21 Hours Ago Forum Superstar, has done so much to help others, they deserve a medal. Has been a member for 9-10 years. Has a total post count of 2,437. Received thanks 279 times, giving thanks to others 7 times.
    So, I really need a lathe with rigid tapping ability and live tooling, but workshop space is restricted, and power supply sufficiently limited to rule out any cheap (aka big!) industrial options.

    I could upgrade my Denford Cyclone to get rigid tapping, but that would mean a period without a functioning lathe.

    A few months ago, while stood threading some parts on my much abused Clarke CL500, I thought the nice flat topped bed would be almost ideal to mount a couple linear rails on, and combine it with a gangtool setup would be somewhere in the ball park of what I'd need.
    But after a bit measuring/sketching, I came to the conclusion the bed would likely be too narrow once a reasonably sized cross slide is fitted and loaded up with my ideal amount of tooling.

    So letting the idea roll around in my head, the big issue is a suitable base. I'm not sure when I had the eureka moment, but that's where my recent post about Epoxy Granite comes in. Why don't I cast one?

    At the moment, I've got as far as sketching some rough spindle/bed shapes, and working on the list of things that will need to be allowed for in the base mould/cast I.e. ballscrew/motor mounts, cable routing, way cover mounting screws (aka the little details that could potentially cause big headaches!).
    I'm probably going to go for a slant bed build, as although it makes the casting/machining a bit more problematic, the swarf management is far better in the long term.

    I'm still very much undecided about the spindle mount. I'm likely to buy a spindle from China, but I'm not sure whether a steel weldment, or another EG cast would be better.

    So this thread is going to be somewhere to list my ideas/thoughts, and for anybody else to add in comments/advise/criticism (I already know this could be very likely end up in a reasonably expensive stupid idea!)
    Avoiding the rubbish customer service from AluminiumWarehouse since July '13.

  2. #2
    Doddy's Avatar
    Lives in Preston, United Kingdom. Last Activity: 8 Hours Ago Has been a member for 6-7 years. Has a total post count of 800. Received thanks 128 times, giving thanks to others 34 times. Referred 1 members to the community.
    Can't offer anything other than the knowledge that I'll be following this thread with interest.

  3. #3
    I will certainly be following this. I'm in the same boat and just starting to retrofit my Boxford 250 for production and build a custom lathe for prototyping . Although I don't need such a large work envelope so looking at a Denford Orac as a base

  4. #4
    If you have a nice flat topped bed and the only problem is that it's too narrow why not fit a ground plate on top of that giving you the required width?
    You think that's too expensive? You're not a Model Engineer are you? :D

  5. #5
    Cant add positive advice.

    But my "simple" saddle swap to linear slides has so far cost 300+ work hours.

    Over 12 fits / fiddle to the ballnut mount, and now servo motor mount, and shear plate/z axis connection.
    New limits, fiddle with servo mount size to the saddle plate to clear the motor mount, ...

    None of it is very "hard" but all of it is slow and heavy (parts assy == 30 kg).

  6. #6
    m_c's Avatar
    Lives in East Lothian, United Kingdom. Last Activity: 21 Hours Ago Forum Superstar, has done so much to help others, they deserve a medal. Has been a member for 9-10 years. Has a total post count of 2,437. Received thanks 279 times, giving thanks to others 7 times.
    Quote Originally Posted by magicniner View Post
    If you have a nice flat topped bed and the only problem is that it's too narrow why not fit a ground plate on top of that giving you the required width?
    I did consider that, but my big concern with that approach, is I think realistically I need at least 18" of cross slide travel, so by the time you hang that length of cross slide over the back along with a servo motor, it's an awful lot of weight pivoting around some bolts that would be around 5" between centres.

    I'm still at the point of adding sketches/notes/ideas to the notepad, and I now have a pretty good idea of the main layout, but I now need to find some time to do some modelling and some calculations to see if my plan is going to work.
    Avoiding the rubbish customer service from AluminiumWarehouse since July '13.

  7. #7
    m_c's Avatar
    Lives in East Lothian, United Kingdom. Last Activity: 21 Hours Ago Forum Superstar, has done so much to help others, they deserve a medal. Has been a member for 9-10 years. Has a total post count of 2,437. Received thanks 279 times, giving thanks to others 7 times.
    So this project has been bumped back up the list, after a slight mishap with my Cyclone (all I'll say is running a 25mm boring bar into the chuck wasn't a good move), and as I'm still waiting to find out if the parts needed to fix the Cyclone are available, this project is getting a lot of attention, as even if the Cyclone is fixed, I'd like the extra capability.

    The current status is an A2-4 6000rpm spindle has been ordered, and is now crudely modelled in Fusion for the purpose of figuring out layout/dimensions.

    I'm currently fleshing out a couple options.
    My main use for this lathe is for gang tooling, with live tools, however I have discovered turrets are available for less money than I thought.

    For those unfamiliar with lathes, the big benefit of gang tooling (row of tools mounted directly to the cross slide) is speed of changing tool. The limitation is part size, and the number of tools you can mount.
    The benefit of a turret, is you can machine relatively far larger parts, but the tool changes take longer.

    In terms of machine design, gang tooling doesn't need much bed clearance as long as tools are on the spindle centre height, whereas a turret requires far larger clearance. To give an example, the 8 position changers I've looked at, typically require 200mm clearance below the spindle centre height.

    I'm currently weighing up whether I want to go to the hassle of designing that high a headstock, for something I might never use.
    If I knew I would still have the cyclone, I probably wouldn't as the cyclone can handle up to ~120mm diameter parts with a fully loaded turret, whereas if I only have gang tooling capability, I'd be limited to either only a few tools with limited Z travel, or small diameter parts.

    I'm now off to model a turret in Fusion
    Avoiding the rubbish customer service from AluminiumWarehouse since July '13.

  8. #8
    m_c's Avatar
    Lives in East Lothian, United Kingdom. Last Activity: 21 Hours Ago Forum Superstar, has done so much to help others, they deserve a medal. Has been a member for 9-10 years. Has a total post count of 2,437. Received thanks 279 times, giving thanks to others 7 times.
    This little 45kg lump got delivered today
    Click image for larger version. 

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    The basic design is slowly progressing. Not quite as quickly as I'd hoped, due to lots of distractions, and quite a bit of contemplation over what layout to go for, but I think I've now got the basic layout decided on. I just need to design it in Fusion to make sure it's going to work as I think it will...
    Avoiding the rubbish customer service from AluminiumWarehouse since July '13.

  9. #9
    That looks expensive.!!!!!!
    -use common sense, if you lack it, there is no software to help that.

  10. #10
    m_c's Avatar
    Lives in East Lothian, United Kingdom. Last Activity: 21 Hours Ago Forum Superstar, has done so much to help others, they deserve a medal. Has been a member for 9-10 years. Has a total post count of 2,437. Received thanks 279 times, giving thanks to others 7 times.
    Quote Originally Posted by JAZZCNC View Post
    That looks expensive.!!!!!!
    Not quite as much as I was expecting, but the 4 servos, 1 three phase stepper drive, and 16:1 reduction gearbox for the mill were cheaper.
    However I did opt for Japanese bearings, and air freight, which was a third of the cost. I did wonder why the air freight was as expensive, until I seen the weight on the delivery label. No wonder the DHL driver didn't want to lift it out his van
    Avoiding the rubbish customer service from AluminiumWarehouse since July '13.

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