Manual control of CNC

Hi,

I am thinking of getting a CNC mill, but from what I can see you can only drive them via gcode etc.

I have tried googling for this, but to no definitive answer.

I was wondering if anyone had connected rotary encoders with handwheels to the CNC controller. Thus creating a mill by wire. That way I could still mill by hand.

Adrian

No point in having a CNC mill if you don't let the computer drive it. Some 'conversions' from manual mills still have handles but those designed as CNC from the start do not. There are no handles on my CNC mill. Manual milling and ballscrews is not a good combination, as ballscrews are poor at self-locking so axes can move when least expected. Some controllers have 'wizards' which allow simple operations, such as facing or pocketing, to be done by entering parameters on screen which the computer then follows without explicitly generating a G-code file. My CNC mill has several wizards, although I've never needed to use them so far.

Andrew

All the many CNC machines I have used feature a 'manual pulse generator', basically a hand wheel which can be used for setting up & manual milling to some degree.

Tony

My Bridgeport clone Has ballscrews and stepper motors. It still has handles and does get used as a manual machine. Yes you do need to be careful with the screws moving but experience and an independent DRO says that this is not much of a problem. That said the machine is a bit of a Frankenstein and is not doing anything of any great accuracy.

The type of control may or may not allow you to add more than 1 encoder and closed loop stepper motors won't let you turn them when off (at least the ones I have won't) so you would need to check out before you commit.

I also have a CNC lathe that currently runs on Mach 3 and while this does only get used with the control on, I have recently bought a couple of rotary encoders to provide some degree of manual movement. When I get chance I will set this up.

You do get faster at using a CNC machine as you understand both the hardware and software you are using so it may not be as much of a problem as you think.

Regards.

David.

I agree with Andrew's comments and will add that a CNC mill needs a computer and some sort of program to tell it what to do, I use Mach3. You can use Mach3 like a manual machine via the axis direction buttons on the key board or screen, adjusting the speeds and feeds accordingly. Just keep your finger on the button. The added bonus is the digital readout for all the axis. No need for G code.

Ian

AdrianR

I have an Emco F1 cnc milling machine that can be used manually or in cnc mode.

When set to Manual mode all the machine axis can be operated by the use of pushbutton switches, this is to allow normal Jogging when setting up a job but you can operate the machine in that manner but I seldom do. The same facility is available as a plug-in unit for most machines.

Link showing axis control at about 3.30sec on Emco F1 cnc mill

**LINK**

Emgee

Edited By Emgee on 19/04/2020 12:49:55

As others have said, the term you need is 'manual pulse generator'. The software you use to control the machine will determine if and how many MPGs you can use.

They can be used by Mach 3. I believe most of the ones you can buy are 100ppr and you can set a distance in the software for how far one pulse moves the axis, so you do not need to spin the MPG like a turbine if you need to move a long way.

You can buy or build a pendant control with E-stop, MPG, axis selection switches and jog distance switches on it.

Lots of information in the Mach 3 archives.

Hi Adrian

I have an Emco VMC mill. It runs on Mach3

There is a jog facility with Mach3, or you can use the keyboard right/left up and down arrows but doing it this way is not pleasant as you have no feel for the work like with a manual mill.

I find I mostly write small programs for it, or use the Mach3 midi function for a direct line input. For example if you wanted to mill a 20mm length, starting from 0, type in X20, (adjusted for mill dia) enter and the machine will do the work. You can set the speed of travel, depth of cut etc.

I also have a manual mill. In my book they are both for very different things, and I wouldn't be without either!

John

Most CNC machines have a manual positioning capability but this is usually a single hand wheel selectable to act on one axis at at time for positioning. There are few technical reasons why a CNC machine couldn't have a manual reversion capability using an arrangement of hand wheels similar to manual machines. These hand wheels do not need to be mechanical connected to the CNC machines ball screws as their function could be replicated electrically. Strictly speaking there may be no need for a computer if the electrical encoders are fitted to the hand wheels provide step and direction signals that can directly connect to the ball screw stepper motor drivers. However some CNC machines micro step the axis motors so the effective "gearing" between the hand wheel and axis movement may be too fine.

This might be a way to test the mechanics of a machine being converted to CNC before splashing out on an expensive computer and software or to check out a machine whose controller is unusable because of license issues.

Being able to use a CNC machine in full manual mode may help when a simple one off task doesn't justify the time investment overhead of CAD/CAM.

Clive

With Mach 3 you can use a Playstation controller for direct movement of the axes.

Rod

Not something I have any serious experience with but surely it's possible to do "manual" control using gcode segments? That is, drive, say, the x-axis at such and such a speed until terminated.

etc

It should be possible to compose a whole toolbox of gcode segments for manual use. In fact I'd be a bit surprised if someone hasn't already done that .... a simple control panel with manual commands.

Or am I all wet?

Adrian;

Any CNC controller (I use LinuxCNC) can have "MPG"s attached. My CNC mills (plural) all have them.

When I worked in a Canadian Govt. research site, the machine shop made one-offs for all kinds of prototypes; one day in there getting some work done for a project, and talking to the machinist, he asked me

"how many manual mills do you see in here?"

I looked around, the place was about the size of a basketball court, and said "none"

His next question was "then why do you use such an archaic thing as a manual mill?"

He showed me how they used a CNC mill for making one-off parts, and I was converted.

I don't even have a pillar drill; all drilling is done on a CNC machine either under program, or hole by hole with a quill and handle.

Something to ponder while waiting for COVID-19 to pass. JohnS.

They are called wizards. Very common, very useful.

Rod, you can also use wireless USB mini keyboards to control Mach3 without the need for a PlayStation controller driver.

Adrian, I would suggest downloading Mach3 and/or PlanetCNC software and look at how manual data input (MDI) works using G0 and G01 commands to move the axes around. For example G0 x0 y0 z0 followed by G01 x100 f25 as an easy start example.

Martin C

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I do quite a bit of basic machining on my Seig KX3 by just manually typing in lines of G code. Manually jogging during setup with all maching done by g code - either manually entered for simple stuff or from CamBam. I don't miss having a manual way to control the machine beyond this.

I believe the Compucut system designed to be run from a 286/386 PC made available from Roger Bertlett who was based at one time in Coventry offered a manual control option of a CNC mill

I've never gone the CNC route but I have had a stepper motor connected to the leadscrew for other purposes and the (lumpy) drag from the stepper when manually feeding was very noticeable and pretty much killed any "tactile feedback". I certainly didn't like it.

Moreover, at the time there was concern in some quarters (refuted in others - this is the internet after all) that back-driving the stepper while it's still connected to its driving electronics is a bad thing to do because of generated voltages. Dunno personally - bit beyond my pay grade.

I use a 'Contour' Shuttlexpress controller (designed for video editing) with Mach3 on the lathe and mill. It works really well, I regularly do manual work with it. There is a plug-in and information on the Mach3 website. Cost £40.

Richard

On my cnc mill running mach3 I use a 6 axis hand controller ( like a PlayStation) and a program called key grabber to have the 5 axis's on my machine under control, just plug the hand controller into a USB port, works a treat if I just want to mill something simple.

Mark