MPG HANDWHEELS

[jholland1]

I am installing T39 lathe kit on Bridgeport Romi lathe. I would like to incorporate existing handwheels with encoders into control CNC7. TB 186says DOS based control cannot utilize Z axis mpg. Can I use the old mpgpic card to accomplish this?
thanks
JH

[cncsnw]

The "Z axis MPG mode" described in that tech bulletin is something completely different (for controlling depth of plasma or water jet on the fly, using a 3-axis mill control).

If you have two encoder-equipped handwheels, then you just need to connect them to available encoder inputs on your CPU board. You should have five encoder inputs, so you have room for both your servo axes; your spindle encoder; and two handwheels.

The handwheel encoders do need to be 5V differential line driver units. Install DB9M connectors per the diagram on your schematic. If the handwheel encoders do not have index pulse channels, then tie the Z and Z/ inputs (pins 6 and 3) to 5V and COM respectively (pins 9 and 2).

See Machine Parameter 128 in your manual for software configuration instructions.

[jholland1]

Progress and questions. Axes 3 and 4 are now displayed on monitor. A turn of carriage handwheel results in display of incremental distance but no motion. X and Z are both displayed below true X and Z. In the PID setup assignment of axis name appears limited to single letters, no numbers or modifiers such as prime symbol.
The major issue is how to link handwheel motion with axis servo motion. A variety of codes entered into parameter 128 did not result in motion. What is the deal with parameter 19? This has something to do with mpg function but confusing in Centroid tech bulletin. Also, the mpg blister switch on pendant, what effect does this have on handwheel function.
thanks in advance for response.
jh

[jholland1]

The tech team at Ajax came thru. I needed to integrate the existing handwheels on Romi cnc lathe. A simple assignment of M to handwheel axis turned function on. Even better, the handwheel feed is two speed as set by blister switch on pendant. I have not peeled a chip yet on lathe but I am impressed with power of software and value of this retrofit package.
I have 5000 line Heidenhain encoders on z and x axes. I strongly recommend this level of encoder density. When you see the ability to dial in one tenth and verify this with dial indicator confidence in operating system and hardware is solid. This is a new lathe and factory proof sheet indicates 3 tenths longitudinal variation.
Next - integrating Toshiba inverter with Ajax Servo3IO.

[jholland1]

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jh