Centroid Community CNC Support Forum

martyscncgarage wrote: ↑Sun May 16, 2021 4:52 pm Roman,
No, I cannot, do drawings of operator panels
Here is my suggestion to, you. Start with a basic Acorn system. Use the Centroid provided schematics as a guide to build your control. If you do not have some basic Electrical or electronics knowledge, and/ or you might have trouble following schematics, find someone that can help you.

Have you posted pictures of your lathe?
Start with the basics and learn to use the control and the machine. Then worry about other enhancements later.

martyscncgarage wrote: ↑Tue May 18, 2021 9:38 am How many speeds does your gear box have? What horse power is the current motor?
I would probably consider replacing the motor with a larger motor and use a sensorless vector VFD like the GS3 from Automationdirect.com or similar.
CNC12 can accommodate 3 speeds as it is, so you could select three most used speeds and go with that.
You will want an encoder belted at 1:1 directly to the spindle for threading and rigid tapping.

As I said before, get the machine running under CNC12 and Acorn, then worry about the bells and whistles.
You have your work cut out for you replacing the leadscrews with good ballscrews and motor mounts for your axis motors

tblough wrote: ↑Tue May 18, 2021 11:44 am CNC12 has provisions for 3 speeds. You will need to add switches to the gear selector to notify CNC12 which gear you have selected, or you can use VCP buttons to manually tell CNC12 which gear range you are using. Marty suggests picking three gear ranges to preserve torque, and then using a variable speed motor drive to vary the spindle speed within each of the three gear ranges. You will not be able to use all four gear ranges, only three, and you will not be able to use the dual speed motor which is why most people change to a VFD.

CNC12 uses the spindle encoder only for syncing the spindle and Z axis for threading.

tblough wrote: ↑Wed May 19, 2021 12:37 pm Many people when converting a gear-head lathe will select a gear range in middle of the settings and leave it there permanently. They then use the Acorn's spindle output connected to a VFD to vary the motor speed and therefore the spindle RPM without having to worry about gear ranges.

If you decide you would rather use the gear box in conjunction with a VFD, then you can choose up to 3 gear ranges. You can choose two (hi -low) or just a single range as above. When using gear ranges, you can either create a custom PLC that figures out from the speed requested, what would be the appropriate gear range and then command a solenoid or some other electromechanical device to do the actual gear shifting automatically.

This is a fairly complicated solution so many choose to do the gear changes manually. In that case, you can use VCP buttons to select gear 1, gear 2, or gear 3 to tell Acorn what gear range you are going to manually shift the headstock into. Acorn would then use the gear ratio you entered when setting up the gear ranges to adjust the VFD speed output to correctly command the motor to run at the right rpm to drive the spindle at the correct rpm given the gear reduction in place.

As far as the spindle encoder goes. Acorn uses the spindle speed derived from the Acorn to adjust the speed of the X or Z axis to maintain the correct feed per rev. If you call out 600rpm and 0.1mm/rev feed rate, the Acorn would normally run the axis at 60mm/min. However if the spindle encoder shows the actual spindle speed as 592rpm, the Acorn will drive the axis at 59.2mm/min. The Acorn WILL NOT adjust the spindle analog output to try and correct the 592rpm to 600rpm.

With a spindle encoder attached, the Acorn will display the ACTUAL rpm derived from the encoder and display that on the screen so you might notice that if you issue a M3 S1000 command, the actual displayed rpm will be 984 rpm. If you don't have a spindle encoder connected to the Acorn, the displayed rpm is equal to the programmed rpm.