Emco PC Turn Turret

Hey,

I'm currently re-rebuilding an EMCO PC Turn 55 that was gifted to me some years back. About 5 years ago I did a basic retrofit with linuxcnc and a chinese BOB and managed to get the thing working, after that it was in storage at my work for the remainder of the time and I've just now taken it back home again. In those days I did not have a huge amount of experience with CNC, so I had made some bad choices, main one being I had not chosen a break out board with enough inputs to allow me to interface with the toolchanger or the spindle speed feedback. I did however implement all the stepper drive controls, limits and PWM to VFD which are all working fine and should transfer to a new BOB easily enough.

I've decided now to move the thing over to a mesa 7i96 to give me the additional connectivity to finally put this into full service with all features. A lot of the hard work is done so it should go pretty smoothly, I hope, I haven't used Mesa cards before though so that will be a new experience. I need to add spindle speed feedback (it is fitted with opto based disk 100 slot plus one slot) and the ATC turret.

So, to get to the point, the next thing I want to approach is the turret on this lathe for tool changes, and here is where I'd appreciate some help (I know next to nothing about these units). I see that there is a new carousel module(?) in 2.8 so I'm guessing that would be the way to go with this in relation to the Mesa when it arrives but I haven't been able to find much info on it in usage so would appreciate some guidance on how to theoretically configure this, if someone wouldn't mind that is.

Info on the turret:

The turret on this lathe is has six positions, with a 24VDC motor driving the unit. After a small disassembly it seems it has a ratchet and pawl mechanism with a stop for each position. The opposite end has two opto-interrupter sensors (the now defuct HOA-2003-001 from Honeywell) which are configured in a pull up arrangement and test out to be functional (scoped on the bench). One seems to be a home position sensor with the other for tool position with a disk to interrupt the opto path at each tool position.

I've sort of reverse engineered the original turret motor drive board which is a DPDT relay (24V) which defaults to reversing the motor at 12V (ish 10.8) at reduced current via four 100R 4W resistors, when coil of the relay is activated with 24V high, the motor will rotate at 24V towards the user, when input signal is low to the coil, it reverses the motor at 12V ish. I'm pretty sure I can interface with this motor driver board easily, I'll knock together a high-side opto isolated sub board to drive the relay coil with 24V, nothing too complicated there. Also, reading the opto-interupters shouldn't be an issue, after reverse engineering the resistor values on the LED's vs the datasheet it's clear they're all configured for 5V supply.

At the moment what I'm struggling to understand how the carousel module would be configured in this case, could anyone give some example of where to start?

Here are some images of the unit for reference.

I thought it might be useful to include some information on the original motor driver PCB, in case anyone else has a similar unit, it might save a few hours of head scratching.

The initial state (relay off) will invert the motor by sending -12V reduced current to the motor which should keep it tight up to the pawl (I assume).

The relays coil is energised at 24V high at the pin indicated in the image in order to rotate the turret for tool changes.

Thanks for the links. Ive been through a good number of those already but there are some ones there that I haven't seen, thanks. Ill read those now. The emco 120 is quite distinct from this unit as it uses greyscale sensors for position so I suppose my question is related specifically to the use of the carousel module in 2.8 with this encoder per tool (index?) plus home sensing arrangement. Maybe I should be in a different area of the forum for such a question though, do excuse me if so. I've read the man page but I'm struggling to translate that to real life settings for this setup.

Okay. Perfect, I'll take a look at that, thanks a lot

You can use the toolerator3000 for this, just got it working for my EMCO 5 CNC.

The toolerator3000 is for the case where you still have the 24 Volt DC motor. it has been written for its bigger brother, the EMCO 120P. So you might have to change the .comp-file (look for % 8 and replace it to % 6) and have to change some timings in the Arduino-sketch.

If you want to modify the turret motor to a stepper, which I did, you can also look into my version of the toolerator. In this version the number of tools can easily be modified with the TOOL_COUNT definition. You can find this version at GitLab

Hey. Thanks for the suggestion. I did look at going this way but decided on the mesa 7i96 board so I've began to implement that along with the carousel functionality in 2.8. I really didn't want to mess with a usb connection even though I use arduino a lot elsewhere. Appreciate you pointing it out though

Thanks for your positive reply!

I've looked into the Carousel functionality, but for a stepper driven turret which also requires to reverse (it's not a Geneva mechanism),, I cannot see a way to make it work on my turret. But I learned something new, which is nice!