Retrofiting an old big milling machine


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Thread: Retrofiting an old big milling machine

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    Default Retrofiting an old big milling machine

    Hello.
    I have found this old bulgarian cnc milling machine for 1500 euros.
    It has some problem with electronics..
    Is it suitable for retrofiting to modern cnc?
    I have no more infos about machine..
    Can you reply me quickly because i must buy it before other one get it.
    Thank you.

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    Retrofiting an old big milling machine-14210623_3_b-jpg   Retrofiting an old big milling machine-14210623_2_b-jpg   Retrofiting an old big milling machine-14210623_1_b-jpg  


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    Default Re: Retrofiting an old big milling machine

    It would certainly be easier to put a new control system on that old mill than to build a mill from scratch. If the ball screws are still in good shape, that would be a plus, as would the ability to use the old motors and power supply. The main things that you can check are the condition of the ways and spindle. Sometimes a mill has been used for a single operation, over and over every day for years. This wears out part of the ways. Try locking it down at the ends of travel, then see if the lockdown screws need more travel to lock it in the middle. If you can run the spindle, see how much runout it shows. If it doesn't run, see if it deflects when you push on it.

    Andrew Werby
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    Default Re: Retrofiting an old big milling machine

    thank you for your reply.
    the machine is far away from me i can not inspect it...
    I plan to retrofit with mesa fpga + linuxcnc
    in 1500 euros he gives me with machine and about 10-15 iso50 tool holders.
    How it seems is a good bargain?



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    Default Re: Retrofiting an old big milling machine

    If the machine is mechanically good, and with 10-15 tool holders I would say it is OK. Mesa + Linux is good.

    Jim Dawson
    Sandy, Oregon, USA


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    Default Re: Retrofiting an old big milling machine

    The tool holders are worth about $100 each (if they're in good shape) so if there are 15 of them you've almost covered the cost of the machine right there.

    Andrew Werby
    Website


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    Default Re: Retrofiting an old big milling machine

    Quote Originally Posted by awerby View Post
    The tool holders are worth about $100 each (if they're in good shape) so if there are 15 of them you've almost covered the cost of the machine right there.
    thank for your reply ..
    you can see some of the toolholders in the last photo.
    that you told the same told me the person sells the machine.



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    Default Re: Retrofiting an old big milling machine

    That does not look like a CNC machine to me, where are the servo motors. The big motor on the right of the saddle box is the power feed and the one on the left is an oil pump. It is unlikely to have ball screws,, what appears to be a CNC control panel is just a pendant with rapid and feed controls, the screen will be a simple DRO readout.



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    Default Re: Retrofiting an old big milling machine

    here is a photo of another machine that same to that iam looking

    Attached Thumbnails Attached Thumbnails Retrofiting an old big milling machine-img_20110422_175851-jpg  


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    Default Re: Retrofiting an old big milling machine

    Have a look underneath the bed you will see straightaway if it is fitted with ball screws. The odd looking limit switch on the front of the bed looks like it is part of an automatic feed system which is controlled by the pendant using a very simplistic control. It looks to me like it came from the WMW works in Romania if you want to check it out and could actually have been made before the Soviet Union collapsed (early 80's) so it is unlikely to have anything like a computer on it. They were marketed in the UK using a variety of meaningless names much like Chinese machines are now. Mechanically they were very well made. If memory serves me well the feed and speed changes were done using hydraulic clutches controlled from the pendant.



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    Default Re: Retrofiting an old big milling machine

    Whats your opinion worth 1500 euros ?Same size machines (non cnc) in my region range from 3k to 8k.If it hasn't ballscrews can i add cheap chinese or better taiwan c7 ballscrews for example 2505 or 2005 ?or such as modification is imposible?
    I have already 2 new 1.8kw 110st-m06030 servos with 2500ppr encoders that accept step-dir/analog +-10V and and an ethernet mesa fpga card to drive the servos from linuxcnc



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    Default Re: Retrofiting an old big milling machine

    It is probably worth the money for manual machining but converting it to CNC would be a challenge to say the least. Ask yourself how and where would you mount the servo's, is there physical room to accommodate the nuts, and the anti back lash bearings for the screws. How are you going to drive the "Z" axis, the knee must weigh at least a ton, you could drive the quill but how are you going to attach a ball screw mount to it. These are the questions only you can answer and many others. I would say you would need 32mm screws at a minimum, that is what is often used on a Bridgeport which is a much lighter machine. Firstly though check the condition of the slide ways as already mentioned by Awerby. They are the most important thing on any machine if you want accuracy. I don't want to sound negative I am sure with enough time, effort and money you could it, but is it worth doing ?, I can't answer that, there are too many unknowns. Personally I would steer clear of it.



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    Default Re: Retrofiting an old big milling machine

    If understand right the motion in Z is done by up-down the table not head.
    You are right driving the Z is extreme difficult it maybe needs 7.5kw servo and a giant ballscrew...
    Perhaps i will buy it as manual machine to fix it and sell it.
    The problem is a power supply so it would be an easy fix..
    The person have it says that the motions in all axis are programmable as is from pendant.
    Also says that mechanically is good.
    Driving Z in this machine how many kw servo needs ? also what ballscrew?

    Last edited by mrsa; 07-12-2018 at 01:12 AM.


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Retrofiting an old big milling machine

Retrofiting an old big milling machine