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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.
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.
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?
If the machine is mechanically good, and with 10-15 tool holders I would say it is OK. Mesa + Linux is good.
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 ..Quote:
Originally Posted by awerby
you can see some of the toolholders in the last photo.
that you told the same told me the person sells the 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.
here is a photo of another machine that same to that iam looking
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.
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
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.
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?
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.
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 ?
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
One local seller sold almost the same machine for 6000 euros.Look the photo it is sold in my region for 6000