How to set my default spindle speed higher?

[countryguy]

My DCAIO will start up at 1000M for the spindle speed. This translates into about 24Hz on the VFD. Since I have a SuperMax Vari-speed Mill I need to also have some measure of speed control from the front face until I can get the unit converted to direct drive If I need to do that?? So as a newb I am wondering:

1) Is there a way to set the startup RPMs to be about 2650 which hits 60Hz on the VFD. From there I can spin the speed up/down from the Mill for now.
Or 2) Is there a way to set this up w/ some type of CNC11/DCAIO parameter settings to avoid taking out the stock speed control?

TIA
CG

[cncsnw]

I am not sure I understand your question.

The speed the spindle "will start up at" depends on whether you have selected Auto or Manual spindle control; what spindle speed override setting you have selected; and, in Auto mode, what speed you have programmed with the S code and what you have set for the expected maximum speed on the Control Configuration screen.

To set up a control so that the speed programmed and shown on the Centroid screen is approximately the same as the actual speed of the spindle, here is what you need to do:

1) Decide how fast you need to run the spindle, in high gear.
2) Think about how fast you want to turn the motor to get that speed.
3) Set the vari-speed dial at a setting that will give you the desired maximum spindle speed, at the desired maximum motor speed.
4) Program your VFD so that its maximum output frequency turns the motor at the desired maximum speed.
5) Enter the expected maximum spindle speed on the Control Configuration screen in the CNC11 software.

On a few VFD's, if you enter a maximum output frequency higher than base frequency (e.g. 60Hz), then you also have to set some parameters to scale the analog reference (0-10V) so that it ranges up to the maximum frequency at 10V, rather than just to base frequency at 10V. On most VFD's this is not necessary, as the analog reference automatically scales from 0 to maximum frequency.

So, for an example, suppose you have a Bridgeport-style knee mill, and you cannot afford the time and expense to change to an inverter-duty motor and fixed-ratio pulleys in the head. You are willing to take a chance on running the vari-speed pulleys at up to twice their design speed, and on running the old motor at up to twice its design frequency. If the motor burns out some day down the road, you can replace it with an inverter-duty motor then.

1) We decide we want to get a maximum spindle speed of approximately 3600 RPM.
2) At 120Hz, the motor will turn a little under 3600 RPM.
3) Set the vari-speed dial to approximately 1800 RPM. That is the spindle speed you would get if the motor were running at 60Hz.
4) Program the VFD for a maximum output frequency of 120Hz.
5) Go to the Control Configuration menu (F1/Setup -> F3/Config -> "137" -> F1/Control) and enter 3600 next to "Max spindle (high range)".

While you are at it, go to the Machine Parameters page and make sure you have Parameter 56 set to 4. That will enable the bar graphs for spindle override and feedrate override in the status window.

With these settings, if you are in high range and have Auto spindle mode selected and the override at 100%, a command like "M3 S1000" should give you approximately 1000 RPM (around 34Hz output frequency). "M3 S3600" would give you approximately 3600 RPM, at 120Hz output frequency.

If you switch to Manual spindle mode, the override setting initially drops to 10%. Therefore if you switch to Manual mode, don't touch the override buttons, and start the spindle using the green Spindle Start button, you will get approximately 180RPM (6Hz). If you turn the override back up to the 100% mark, you will get approximately 1800RPM. If you turn the spindle override up to 200%, you will get approximately 3600RPM.

In other words:
1) In Auto mode, the spindle override is the percentage of the programmed speed
2) In manual mode, ranging the spindle override from 1% to 200% gives you from 1/200 of maximum speed up to maximum speed.

If you have a low gear range, and you want to have correct spindle speed and direction in both ranges, then you need to install a spindle range detect switch (so the PLC can see when you have shifted into low gear), and you need to set Machine Parameter 65 to the fraction of high-range speed that you get in low range. If your low range uses a typical Bridgeport-style back gear which reverses the direction of rotation in low gear, then you should make Parameter 65 negative. E.g., for an 8:1 ratio with direction reversal, set Parameter 65 to -0.1250.

[countryguy]

Thank you for the detailed response! This was exactly what I wanted to know. Much appreciated
CG.