Messages

791

Mach4 General Discussion / Re: dangerous malfunction of a machine driven by Mach4

« on: February 23, 2022, 09:05:57 PM »

Hi Hakan,
I think your'e over doing it, even 32mm has a stiffness of 1100N/um, easily twenty times the stiffness of my machine. Many comments I garnered from CNCZone concluded
that my ballscrews were too big for my machine, 800kg, with 150kg X axis weight.

I would expect 40mm diameter screws to be found on machines requiring 100kN or more of thrust and an X axis weight of tonnes...not hundreds of kg's but tonnes.

When I was finding parts for my new mill I like you thought the bigger the ballscrew the better...right? Wrong, a large diameter ballscrew, or at least an out-size ballscrew, requires huge torque
just to accelerate and that counts against toolpath following. As it turns out I can still get 0.25g with the ballscrews I've got with 750W servos, but I would have done even better with 25mm
ballscrews. When it comes to rotating components bigger is not always....or even normally....better.

792

Mach4 General Discussion / Re: dangerous malfunction of a machine driven by Mach4

« on: February 23, 2022, 06:31:58 PM »

Hi,
I did the calculations with my 32mm diameter 5mm pitch screws and the inertia is totally dominated by the rotational inertia of the ballscrew, not the 150kg axis weight.

The breakdown went like this:
85% rotational inertia of the ballscrew
10% rotational inertia of the servo rotor
5% linear inertia of the axis.

Given that the first moment of inertia of a ballscrew goes as the fourth power of diameter I would guess you situation more like 92% of the inertia is in the ballscrew.
Why such large diameter screws? Mine were outsized at 32mm...but they were what I could get.

Craig

793

Mach4 General Discussion / Re: dangerous malfunction of a machine driven by Mach4

« on: February 23, 2022, 06:25:26 PM »

Hi,

Delta is also nice but its my second choice because approx. same price you can buy a yaskawa/panasonic from China or even from ebay if u catch the right bid.

All the sites I seen selling Yaskawa are  double and triple for the equivalent Delta.

Craig

794

Mach4 General Discussion / Re: Mach4 Lathe: Displaying spindle rotational angle?

« on: February 23, 2022, 04:34:43 PM »

Hi,
I use an ESS and I imagine the PoKeys will at least be broadly similar.

Craig

795

Mach4 General Discussion / Re: Mach4 Lathe: Displaying spindle rotational angle?

« on: February 23, 2022, 04:19:13 PM »

Hi,
OK, you are going to have to hook the encoder via to the PoKeys, I presume the PoKeys has MPG and/or encoder inputs.
The PoKeys will probably report to Mach in the form of a register. Open the register diagnostics and scan through the PoKeys registers until
you find it.

Craig

796

Mach4 General Discussion / Re: Mach4 Lathe: Displaying spindle rotational angle?

« on: February 23, 2022, 04:11:53 PM »

Hi,
what motion controller are you using?

Craig

797

Mach4 General Discussion / Re: Mach4 Lathe: Displaying spindle rotational angle?

« on: February 22, 2022, 10:51:24 PM »

Hi,
I'm guessing that the encoder is actually an auxilliary encoder output from a servo?

What motion controller are you using?

You will need at least three spare inputs, A, B, Z. Mach can deduce a number from those input, and that number can be
manipulated to represent an angle in degrees or radians and then be displayed as a DRO.

Craig

798

Mach3 under Vista / Re: ERROR: Following Error Limit Exceeded on Axis #. Servo Disarmed

« on: February 22, 2022, 09:41:25 PM »

Hi,
Following error occurs when the commands to a servo are not obeyed and the distance between where the servo actually is, and where Mach commanded it to be, exceeds your programmed threshold.

Is the encoder hooked up properly?. If the encoder is not hooked up or hooked up backwards then the controller will have no idea if the servo moved or not and will very quickly generate a Following Error.

Craig

799

Mach4 General Discussion / Re: dangerous malfunction of a machine driven by Mach4

« on: February 22, 2022, 08:08:06 PM »

Hi,
what sort of machine requires 16Nm?

I have bought and used 750W Delta B2 series servos which are 2.4Nm rated, and 7.1Nm overload and they kick arse!
While I can get 25m/min rapids and 0.25g accels, its too aggressive and I back in off to 15m/min and 0.15g....and that's still scary fast.

Craig

800

Mach4 General Discussion / Re: dangerous malfunction of a machine driven by Mach4

« on: February 22, 2022, 08:03:53 PM »

Hi,
closed loop steppers do offer an advantage of higher resolution, but that's about the only advantage. The manufacturers claim 'they
go faster, more power, never lose steps'....pure BS. Closed loop steppers are still steppers and they lose torque at speed just like any stepper,
closed loop doesn't do squat about that.

If you want true closed loop performance, don't waste your money on closed loop steppers, get servos. A servo will eat any stepper ever made.

Craig