Multiple mpg handwheels

[Scary]

Hi all.
I have just received my acorn (still in box ). I have been looking at how I am going to mount the servo motors on the lathe and have found there is no practical way to keep the manual handwheels. I really need to keep manual control as I do alot of small fiddly maintenance type work and even with conversational,
it would be painful to use CNC all the time. Is there any way to connect two mpg handwheels (one for X, one for Z) to allow "manual" machine control simultaneously. I know I will loose the feel through the servos but at least I can throw somethingin there and touch it up easily

[Nigelo]

Review Centroid's WPMG which is worth every penny/cent.

We don't know limitations of your machine but take a look at how Wabeco in Germany mount their stepper motors and provide these motorized axes WITH hand controls. The manual for my manual Wabeco D6000 shows the following:

X Axis

Z Axis Tailstock end

hope this helps

[tblough]

Switch to Oak. There is no way to have multiple handwheels on Acorn with only one encoder port.

[tblough]

The Wabeco method will not work with Acorn since it's an open loop control. When you manually turn a handle, the Acorn DRO positions will not update.

[BDubs]

Just a quick reality/sanity check...

In what real life situation do you need to turn both handles at once? Most operations are going to be locking one axis and positioning the other with the handwheel. Thinking facing, turning etc. The only thing I can think of requiring 2 is a chamfer...but you'd want to do that via gcode anyway. Everything else is intermittent/incremental movement and that's quick and easy on the pendant. What am I missing?

[martyscncgarage]

Just a quick reality/sanity check...

In what real life situation do you need to turn both handles at once? Most operations are going to be locking one axis and positioning the other with the handwheel. Thinking facing, turning etc. The only thing I can think of requiring 2 is a chamfer...but you'd want to do that via gcode anyway. Everything else is intermittent/incremental movement and that's quick and easy on the pendant. What am I missing?

No,
Both handwheels were usually put on CNC machines for "Manual Machinists"
The Centroid Wireless pendant will do what you need it to. It has an axis selector knob on it. You'll be manually be moving one axis at a time anyway....

[Nigelo]

The OP's question was to facilitate manual operation for situations where cnc was an unnecessary complication. In that situation, Acorn is powered off.

My lathe is fully manual for the moment but my Wabeco Mill uses exactly the same setup with a quill and manual ops are useful on some, admittedly rare, occasions.

[Scary]

Wow, thanks heaps for all the replies. To answer a few questions I will explain my situation as it is a bit different to the normal. (Excuse the long post).

I provide a mobile machine maintenance and fabrication business for rural and remote areas of Australia and quite often I am working in very remote areas running of diesel generator (single phase). My whole workshop fits into a 20ft shipping container that gets loaded onto an off road truck for transport between jobs so size, weight, power consumption and reliability are all very important and part the reason I have not gone to cnc many years ago. With the large amount of equipment and most of it custom made to be multi functional, I can do everything from mill, lathe, internal spline forming, gear cutting/hobbing, shaping, surface grinding, cylindrical grinding, portable line boring, case and through hardening, metal casting, powder welding, EDM sinker, Sectional roll forming etc. I think you now understand the limited space I have available.

Back to the lathe in question. It is a fairly standard 1m bed, 300mm swing over carriage type Center lathe. I have no trouble with the Z axis mounting as I am replacing the acme threading rail for a ball screw and have the servo mounted on the tailstock end. I am machining a new half nut arrangement to be a taper that locks onto the ball nut to allow me to quickly disconnect from the ball screw to allow manual function when required. I am not concerned about loosing the DRO on screen as I have both the hand wheel indicator and stand alone DROs fitted to the machine. I also understand that I will loose manual threading availability but conversational programming will certainly make up for that.

The issue I have is with the X axis. I cannot seem to find a way to keep the handwheel. I can’t mount the servo on the back side of the cross slide as I am too close to the wall and I can’t belt drive to a lower or side position and mount the motor facing the other way as it interferes with the bed or working area of the lathe. The only way I can find is to direct mount it to the front, removing the handwheel. Upon replacement of the acme for ball screw, I am going to remove the front section and machine a recess into the saddle to mount the servo further into the lathe and mount ball nut on carriage accordingly. I need to create more room for the operator as there is limited space between the lathe and bench behind. Fitting a belt arrangement will space it closer to the operator by about an inch which doesn’t sound like much but will make a huge difference given the already limited space available.

The question has been asked as to why I would still need manual functionality. Picture this scenario, one I come across regularly. You are given a bent/broken PTO driveshaft to repair. You cut out the tube from the ends and then need to machine off the welds until you see the seam to remove tube from the yoke. With a manual it is easy to wiggle the Z back and forth while slowly increasing the cut until you can see the join. With CNC it will be more difficult as you don’t know any specific coordinates and it is done mostly by sight/feel/sound. I am sure you get the idea. The same goes for welding up worn bearing surfaces on shafts, you just “wiggle” your tool in until it cleans up to allow for welding and turning down again. Machining the weld down should be simple enough with CNC but to prep, once again left/right/depth have no real coordinates and are done by feel to remove the least amount of material. To change between axis on a single handwheel would be painful in these situations. Keep in mind this machine has also been modified to allow shaft balancing capabilities, another function that will be manual however single axis movement will be fine for this.

Is there a way I can “turn off” the z axis or ignore it through the cnc software. I don’t want the shaft rotating with a free floating ball nut when it is disengaged. This would allow me to use the MPG for X, and manual Z. The servos are closed loop to the servo controller and servo drive sends an out of position alarm to the acorn meaning that I can’t just manually “unplug” the motor. I also don’t really want to interfere with any switching of wiring, I would much prefer to do it in software if possible. Are there any other ideas to gain the functionality I require?

I really appreciate the help so far and it is refreshing to find a forum that is helpful rather than the usual trolls one finds nowadays.

[tblough]

As I mentioned before, you can do exactly what you want with Oak (ac servos) or AllIn1DC (DC servos). I have a converted Hardinge TFB with an Oak controller and encoders added to the original handwheels in the apron along with microswitches on the original feed control levers.

This allows me to operate the lathe manually EXACTLY like the original lathe with only the loss of "feel".

Here's my thread on building it:
viewtopic.php?f=57&t=1098&hilit=Hardinge

And here's a thread on dual handwheels and joysticks (feed control levers on my machine):
viewtopic.php?f=64&t=3116&hilit=Hardinge

[Scary]

As I mentioned before, you can do exactly what you want with Oak (ac servos) or AllIn1DC (DC servos).

I can appreciate this however, I have an Acorn, I do not have an oak and I am reluctant to purchase another system on top of the one I have. Unfortunately, inexperience on my part has led me down this path and I am trying to deal with what I have. I will keep the oak in mind if/when I do the milling machine