New lathe purchase


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Thread: New lathe purchase

  1. #1
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    Default New lathe purchase

    Hello,

    I want to buy a lathe, but have no experience with such machines, so I would like to ask for some knowledgeble opinions.

    I am opting between 2 lathes:
    1. Bernardo profi 700 pro including DRO
    https://www.bernardo.at/en/profi-700...eige-i200.html

    2. Paulimot PM4000 + DRO
    https://www.paulimot.de/drehmaschinen/pm4000/dro

    Main differences between the 2 are:

    1. Bernardo is 3000 RPM with VFD vs. Paulimot 1815 RPM with 9 speed gearbox
    (+1 bernardo)

    2. Bernardo has 700mm between centers vs. Paulimot which is 900mm
    (+1 Paulimot)

    3. Bernardo has electric motor start/stop vs. Paulimot has a lever on the carrige
    (can not decide which is better. I see advantages for both)

    4. Bernardo has no footbrake vs. Paulimot which it does
    (+1 Paulimot)

    5. Paulimot is +100kg heavier
    (+1 Paulimot)

    6. Bernardo has local dealership vs. Paulimot which is shipped from Germany
    (+1 Bernardo)

    All the rest being equal from technics down to the price, which would be your choice?

    I like the footbrake idea + biger center distance of the Paulimot, but is the extra 1200 RPM of the Bernardo really make a difference? Is this extra speed worth it?

    Thank you,
    Andrei

    Sent from my SM-A520F using Tapatalk

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  2. #2
    Member ninefinger's Avatar
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    Default Re: New lathe purchase

    The large machine (Paulimot) is a better value in my opinion, based on a quick review of the specs. The gear box is not a negative but rather a positive. It allows the motor to develop full power and convert that into rpm or torque. The VFD can alter the speed but it will only generate the same torque at low speed as it does at high speed - this is a big limitation for a lathe in my opinion. Turning a large diameter item requires lower speed but high torque that the VFD will not provide. Lastly - you can always change the motor in the future and add a VFD but you can't really add a gearbox...
    The max rpm should not be a concern either in a non production environment and unless you are turning really small parts all the time it won't matter.
    Lastly the spindle nose on the Paulimot appears to be better in that it is a standard cam lock style making chuck changes easy, not to mention easy to source alternate chucks. The Bernardo has some sort of bolt on which gets old if you want to switch between chucks frequently.

    Mike



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    Default Re: New lathe purchase

    Quote Originally Posted by ninefinger View Post
    The max rpm should not be a concern either in a non production environment and unless you are turning really small parts all the time it won't matter.
    Mike
    Hi Mike,

    Thank you for your answer. What does really small parts mean?

    Anyhow I will be fitting a VFD because I only have single phase in my shop.

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    Member ninefinger's Avatar
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    Default Re: New lathe purchase

    When machining its about the cutting speed - i.e. how fast the material is moving at the cutter point. Different materials and cutters have different recommended speeds expressed as SFM (surface feet per minute) or meters per minute. So a few examples will show what is small:
    5mm diameter mild steel being turned using a high speed steel tool the recommended surface cutting speed is 37 m/min which requires ~1750 rpm.
    5mm diameter aluminum (6061) using the same cutting tool the recommended surface speed is 152 m/min so the rpm is 7277 rpm.
    Using carbide tools will result in an even higher recommended speed but usually the small machines can't provide the power required, never mind the speed.
    Larger diameters will achieve the surface speed with less rpm...

    You can very well cut at less than the recommended speeds - its just that you won't be as efficient / fast. As I said, unless you are a manufacturer it doesn't really matter in my opinion. Also, not many manual machines have chucks that are rated to spin that fast, and standing in front of one that is spinning like that would scare the !@%$#^@ out of me!
    Mike

    Last edited by ninefinger; 03-27-2019 at 07:32 PM. Reason: additional comment of chuck rpm limits


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    Default Re: New lathe purchase

    Ok. I'm convinced. Will go for the Paulimot.

    Did a little more digging. It is actually a rebranded Grizzly 12x36 or Optimum 320x900.

    Actually where I work there is an Optimum 320x900 and the guys operating it gave it good references.

    There is also Optimum available but more expensive and without factory DRO. Therefore, no.

    Sent from my SM-A520F using Tapatalk



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