Messages

81

General Mach Discussion / Re: Z speed limiting xy speed

« on: February 13, 2018, 06:46:27 PM »

When moving 3 axis simultaneously the actual feed rate is along the vector between the 3 axis. So if Mach 3 sees the Z distance as a long move then motion along XY will be slowed a lot. Your Z move needs to be seen as very short by Mach 3. Maybe setting the step pulses per unit move to a very high number would do the job.

82

General Mach Discussion / Re: Nmotion Controller

« on: February 09, 2018, 01:27:04 PM »

An apropo saying “ Never attribute to conspiracy ( or step error) what can be explained by stupidity”

83

General Mach Discussion / Re: Nmotion Controller

« on: February 09, 2018, 01:24:48 PM »

Same here, no missing steps ever except for when I do stupid. However I just machined a stainless part that took 2 hours and the center hole is perfectly round and NOT concentric with the round housing all cut at the same time! However I suspect a loose coupling between a motor and ball screw as the culprit. Missed steps would have been way more random.

84

G-Code, CAD, and CAM discussions / Re: Using Catia with Mach3

« on: February 09, 2018, 01:19:43 PM »

The big boys like Catia have always gotten big bucks for post processors. Many really hot CNC programmers write their own posts to match the kind of work they do, and the VARS that have people that can do it for customers see this as great profit center.

I use SolidWorks and CamBam for programming. Not nearly as powerful as the Catia solution. However it runs on the same underpowered old PC as Mach 3 on the machine making changes really quick. It has rudimentary drawing capabilty and I can stand there wirh my calipers in hand and knock out a workable program in seconds. At 40 sessions before you buy and $149 I rate it as a very good value. We have a second copy on the big machine in the shop that isn’t Mach 3 too.

85

G-Code, CAD, and CAM discussions / Re: Mach3 Error when running G-code

« on: February 07, 2018, 10:53:36 AM »

Your g-code shows a diameter of about 12” so the problem is with Mach 3 settings not V-carve.

86

General Mach Discussion / Re: Mach3 spindle RPM OFF!

« on: January 26, 2018, 01:55:28 PM »

On commercial CNCs with ridgid tapping 3 phase motors and inverters are the norm for spindle drives.  On the Fadal I ran you had to use the high speed range for ridgid tapping too. So I believe the answer here is that the spindle position encoder is used to sych the Z axis to a spindle that is changing speed and direction, instead of trying to closely control the spindle speed. The problem here is that Mach can’t close the loop this way without help from a motion controller.

87

General Mach Discussion / Re: Mach3 spindle RPM OFF!

« on: January 25, 2018, 07:04:34 PM »

I don’t think you will get better than that with a motor to controller mismatch like that.  Are you running the motor in its normal direction? The brushes are offset for rotation in one direction only on many tread mill motors. Running backwards my treadmill motor went up in flames!

88

General Mach Discussion / Re: Mach3 spindle RPM OFF!

« on: January 25, 2018, 07:02:53 PM »

I don’t think you will get better than that with a motor to controller mismatch like that.  Are you running the motor in its normal direction? The brushes are offset for rotation in one direction only on many tread mill motors. Running backwards my treadmill motor went up in flames!

89

PoKeys / Re: Pokeys57cnc 10v spindle control only reaches 8.1v

« on: January 25, 2018, 06:35:37 PM »

The pokeys output current is too low to drive the input impedance of the VFD. So you will need an amplifier circuit that can provide more drive current than the Pokeys. I know the why, but I am not not an electronics guy to suggest a circuit.

90

FAQs / Re: Intermittent inaccuracy

« on: January 24, 2018, 01:20:47 PM »

My Z axis has a gas spring counterbalance because it is heavy and ball screws back drive so well that it comes right down if I hit E-stop or loose power.  This also means the stepper motor doesn't have to overcome the weight of the Z and the load of cutting, so it never misses steps.