Denford Software & Machines

As a newbie to this great site I am in need of some help. With such a wealth of info on this site I am hoping someone can help me.

Just bought a 1983 Orac from my local engineering company who bought it many years ago but never used it so although it was covered in filth it is pristine underneath. I was going to convert it all to mach3 with new steppers and electronics but I think I would like to keep it all original for the moment.

Now here in lies the problem. Switching on with the E/S button pressed in is fine. The screen lights up and you can program ether manually or from cassette etc, but if you release the E/S button the is a loud buzzing sound from inside the electronics enclosure and the screen flicks to rapid feed. I hit the E/S button to stop it. I am assuming a relay is stuck or could it be a stepper although I am sure it is coming from the electrical bay. I have thoroughly cleaned out the bay with compressed air but not sure where to look or start. I am hoping it is nothing serious.

Can anybody point me in the right direction as to where to look first or to testing individual items so as to isolate the problem.
Many Thanks
Paul.

Hi Paul

When you release the EM stop switch and the buzzing starts the machine is in Manual operation mode, you should be able to move the Z and X axis with the push pads on the Manual console.
Using the centre switch you can toggle between Fast, Slow and Step speeds for the travel.
To get to programming mode from Manual mode press the small red Stop on the manual control console, this takes you to the Home screen showing the 7 choices available.
The buzzing noise could be from a contactor with dirty pole faces, this would prevent the poles closing completely so would be chattering.
I suggest you remove the rear hinge down panel and check any plug in relays or contactor pole faces, use a contact spray on the pins and plug in and out a few times to ensure good contact.
I have the same lathe and use it in the original form, for the model maker it will handle most jobs.

Rgds, Emgee

Hi Paul
Video showing my lathe cutting a thread for a tap.

https://youtu.be/Ev0zllycnHQ

Emgee

Hello Emgee.

Thank you for posting your replies.

I eventually traced the loud buzzing to the toroidal transformer. I guess the plates are vibrating wildly but with continued use it has slowly quietened down to a very low audible hum.

I have used the manual buttons like you said but the X axis will not move. The red led illuminates on the control board. The ball screw is free and the stepper turns ok so I am not sure whether it's related to the second problem. The Z axis only moves away from the chuck whichever in/out button you press. The spindle runs ok and speed change works fine.

I guess I will try a simple program and see what happens.

Again any advice would be appreciated.

Check the X axis is not driven onto the limit switch, limit override switch is under front console just about in line with the manual control buttons, press in and hold at the same time press the X axis travel out key, this will drive the operating rod off the limit.
Marcus

You may be best swapping over the X & Z drives & see if the fault follows the drive.

Thanks for the replies guys.

I checked the limit switches and neither axis had reached the limits.

I was about to swap the axis boards but they are no both dead with no power to them. The spindle also does not work although the manual switch is clicking the relay. I though it may be a fuse but I have checked all the fuses I can find and none have blown. I guess the power supply for the drivers is at fault. Can anybody help me identify where it is located.

Also the machine had a large mouse nest in it. I have cleaned it all out but a few wires have been chewed but not causing problems I think. If it cannot be fixed easily I am seriously thinking of going down the route of removing the electronics and fitting modern drivers for Mach3 etc.

It has probably been mentioned on here several times but what bits can one keep when converting. I assume steppers and vfd etc.

Thanks again.