Retrofiting an old big milling machine - Page 2


Page 2 of 2 FirstFirst 12
Results 13 to 16 of 16

Thread: Retrofiting an old big milling machine

  1. #13
    Registered
    Join Date
    Apr 2015
    Posts
    119
    Downloads
    0
    Uploads
    0

    Default Re: Retrofiting an old big milling machine

    It is hard to tell from the photo's but it looks like there is a quill on this machine. if that is the case then that would the better way to go. If you were to use the knee for ""Z motion I would start by fitting some type of counterbalance system, probably compressed air cylinders that can use a regulator to achieve some balance. If you could achieve that then even a modestly sized servo would be good enough if it is geared down using a 3 or 4 to 1 ratio. Inertia will be a bigger factor than weight. Physically fitting a ball screw could be difficult because on some machines you may need to remove the knee to get the screw out. Generally speaking you will need a ball screw of a similar size to the existing one and that will be around 50 mm at a guess. Not a cheap screw and I am not even sure that rolled screws are available in that size. How are you planning to turn the screw,?. The only practical way as far as I can see would be to fit the motor inside the knee. There will be a lot of work involved. There will be a bevel gear keyed on to the screw. This in turn is driven by another bevel gear that is mounted on the back of the main feed gearbox casting. If you remove the front of the knee where the handles fit you may well find that the entire gearbox and drive train will pull out as a complete unit. It will be heavy and awkward. Often it is easier to remove the knee and turn it on its back so a crane can be used to lift it out. Once it is out there will just be the main drive motor and the remains of the hydraulic system which powers the clutches and provides lubrication in most cases. You should then be able to asess how easy it will be to remove the screw and get some idea as to where to mount the drive there should be plenty of room inside but of course you will have to dispense with the original drive mechanics which will make the machine totally dependent on servo's. you will not be able to move the axis's by hand after you have disabled the existing system.. I am only generalizing based on working on similar machines, this could be different. It would help if you could identify the manufacturer. Any markings or names could be in Russian. I hope you have a crane of some kind.



  2. #14
    Registered
    Join Date
    Jul 2014
    Posts
    32
    Downloads
    0
    Uploads
    0

    Default Re: Retrofiting an old big milling machine

    Some news..
    Z axis movement is done only by table movement only by knee not the head head is fixed.
    The big black motor shown in the right down on the photo moves all axis X Y Z each times makes 1 axis movement
    and change axis by coupling mechanically to each axis.
    spindle is about 7.5kw machine weight 2.5tons .
    The ways are in good condition.
    The machine is made in bulgaria from 1980 to 1990.
    I think that can not be converted to cnc...
    But what is your opinion as manual machine ?

    Last edited by mrsa; 07-12-2018 at 07:23 AM.


  3. #15
    Registered
    Join Date
    Apr 2015
    Posts
    119
    Downloads
    0
    Uploads
    0

    Default Re: Retrofiting an old big milling machine

    If the bed ways are good and it runs OK then it is worth buying. It would be worth rather more in the UK, I would say around £6000 and would be worth even more in India or Pakistan where most of our old machines go. The only problem is that spare parts will be almost impossible to obtain and the electrical system and parts will be incompatible with modern equivalents. I have never encountered any machine made in Bulgaria but as I mentioned before was probably built while Bulgaria was still an Eastern bloc country and the design would be from a Russian design bureau and is likely to be fairly generic using common components. It was common for machines to be shipped into another country from Russia without any electrical system. This would be finished off in the recipient country using locally sourced components and then the machine rebadged giving the impression it was built locally. Often electrical parts in European machines would be sourced from Seimens.
    Good luck



  4. #16
    Registered
    Join Date
    Jul 2014
    Posts
    32
    Downloads
    0
    Uploads
    0

    Default Re: Retrofiting an old big milling machine

    One local seller sold almost the same machine for 6000 euros.Look the photo it is sold in my region for 6000

    Attached Thumbnails Attached Thumbnails Retrofiting an old big milling machine-freza-bulgaria-big-jpg  


Page 2 of 2 FirstFirst 12

Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  


About CNCzone.com

    We are the largest and most active discussion forum for manufacturing industry. The site is 100% free to join and use, so join today!

Follow us on


Our Brands

Retrofiting an old big milling machine

Retrofiting an old big milling machine