• Your membership appears to have expired. Please consider renewing your membership to the OTI as the dues are used to support the great content within the site, the Symposium and all the educational content for new and established ornamental turners. PLEASE CLICK HERE TO RENEW YOUR MEMBERSHIP If you believe this message is in error, please contact our Treasurer Thank you.

Automatic vs Manual operation of CNC machines


New Member
I'd like to start a discussion on the relative merits of automatic vs manual operation of CNC machines for OT work.

What I mean by "automatic" operation is the way that CNC machines operate today. The software generates a complete G-Code file, this is loaded onto the CNC machine, the "Start" button is pressed, and the user stands there with his hands in his pockets while the machine does everything automatically (with the possible exception of tool changes).

"Manual" operation has the user more involved in the operation of the CNC machine. There have been two methods suggested for this:
  1. The machine operates automatically, as above, until the user presses "Pause". This stops the machine. The user can then adjust settings in the software and press "Start" to continue from where he left off (but with these new settings now in effect).
  2. There are one or two handwheels attached to encoders that the software reads as it's feeding instructions to the CNC machine. The user turns these handwheels, just like on a real OT machine, and the software simulates the change in settings in real-time on the CNC machine. In this case, the machine may not be able to operate automatically at all.
Either manual approach requires the simulator software to be "in the loop" driving the CNC machine in real-time, rather than generating a batch G-Code file. I don't know if there are standard software interfaces defined for this kind of operation of CNC machines.

My experience so far has only been with the automatic operation, as that has been the only option open to me. While getting the entire run set up can be quite tedious (lots of numbers and calculations!), it does represent a full record of what was done. This allows you to go back and revise your settings as many times as you need to in order to continually improve the quality of the result. But it also means that there is a considerable delay (hours or even days) between changing a setting and seeing the result of that change.

I would like to hear other peoples experiences and thoughts on this! This is an area that I would like to explore with the OT simulator software...



New Member
Re: automatic versus manual


I am aiming for a semi manual system as my ultimate goal. I want the headstock and pumping movements to be digitally based but allow the user to manually adjust the cutter position, orientation and depth if they want too. Now when I say manual I also include manual digital in that the depth and angle of cut may be governed by a stepper system but this ought to be independent of the system running the spindle and pumping movements.

So my ultimate setup will be two parallel digital systems, one controlling the spindles and the other controlling the cutter depth, angle, position etc.

My intention with the spindle system is to have software on a pc to design the rosette combination to give the shape I want but then to download this data to a small independant processor that controls my equipment. I also want to be able to have this running continuously so that the spindle rotates and the headstock moves continuously just like a purely mechanical system, but allow it to be paused and during the pause have the ability to jog an axis to a new position if required.

My intention with the cutter system is to be able to set up depth stops, and allow for a depth movement, or jog or whatever to mimic how someone with a manual system works.

So in fact in the future I see no reliance on gcode or emc like interpreters even though they are essential to me at the present.

Finally why do it this way? well the simple answer is because I want to but also I think that it is also the way to impart craftsmanship to the pieces I make. I am still relatively new to this area and there are many much more experienced people in this forum who could profitably suggest to both of us how best to retain a craftsmans approach whilst making the best of what digital control has to offer.

So that when someone at the SOT tells me its all just automatically created at the press of a button (even with the few pieces I have made so far I know that even using emc you cannot do that but have to carefully set things up.) I can emphatically say no its not and argue that my machine is just the same as theirs except that their control is a mechanical disc and rubber whilst mine is a processor.

Anyway I will get off the soapbox now :lol: and await your comments / reflections.