Topics

41

Show"N"Tell ( Your Machines) / My New CNC

« on: June 02, 2017, 02:47:57 PM »

This is my last CNC which I made with 3/8" & 1/2” thick T6511 Aluminum Flat Bar/Plate, Grade 12 alloy bolts, 48"x34"x24" support table on casters, Aluminum T-Slot table top 42"x30", Approx. Cutting area 36"x29"x6", 1.5KW VFD with 800W water cooled 24K RPM Spindle with 3 ER11 collet, Water temperature indicator with audible alarm, Gecko G540 Controller, Four 281oz.in motors,  Limit Switches in all axes, Cable Carriers on A & X, AutoZero Z Axis Probe. Video of first cut here:
https://youtu.be/kR-7OlmeVkM

42

General Mach Discussion / What is this RPM Line

« on: March 19, 2017, 04:42:32 PM »

On the attached snip, what is the purpose of the RPM line circled in red? At the bottom where the two zeros are I can see my spindle RPM but the red circled line always shows 0

43

General Mach Discussion / RPM / Feed Rates Again?

« on: March 12, 2017, 10:47:39 PM »

Searching on this subject I find a lot of answers but not what I’m looking for

For example I found this formula: ChipLoad x CutterDiameter x Number of Flutes x SpindleRPM = FeedRate in Inches/min.

Perhaps I’m wrong but the above formula does not take into the account how much material we hog per pass. Is the above formula correct regardless the depth of cut?

I was hoping to find a table summarizing most materials but I didn’t find any

I’m working on MDF and I found the ChipLoad for MDF is 0.1 to 0.18. Using 0.18 to the formula above with 1/8” Single Flute at 18000RPM gives me a feed rate of 405 inches/min. I wouldn’t even dream to use this kind of feed rate so either I do something wrong or the formula is not applicable for MDF material.

Anyone knows what the feed rate will be if I use 1/8” Single flute on MDF? (my spindle can go from 6000 – 24000 RPM and normally I take 1/16 to 1/32 per pass).

44

General Mach Discussion / What is Step Pulse / Dir Pulse?

« on: February 23, 2017, 07:33:20 PM »

Cant find any info on the manual but would like to know what the values for “Step Pulse” & “Dir Pulse” do to a stepper motor in the Motor Tuning and Setup Screen

Are any guidelines on the settings? (the screen shows 1-5us)

45

General Mach Discussion / Y&A Axes Move the Wrong Direction

« on: February 12, 2017, 07:29:11 PM »

Y&A Axes Move the Wrong Direction

When I stand in front of my cnc, X axis moves left / right, Z axis moves up/dn and the Y/A axes moves away from me or towards me (up/dn). To avoid confusion X axis moves with the right/left arrows, Z with the page up/dn arrows and Y&A with the up/dn arrows.

All is set correct except the Y&A. I have been playing with the Active Lows on the input signals and motor outputs plus clicking the Reverse in the Homing/Limits with no success. I can get Y&A to move up/dn the way I like it but then when at the MID screen I type G0Y1.0 the axes moves up (away from me) which is the negative way and I think it will create a conflict when I start a gcode.

In comparison the X axis when I type G0X1.0 modes to the right and Z when I type G0Z-1.0 moves down which both are correct

Any ideas what I do wrong?

46

General Mach Discussion / Mach3 PWM Settings

« on: February 08, 2017, 06:14:10 PM »

Reading on the web some say that the Mach3 Motor Tuning and Setup screen has no affect when using PWM and some say to set the Stepsper to 1000, increase the Velocity / Acceleration to maximum and set the Step pulse to 5, Direction pulse to 1. I wonder which one is true

On my PWM system with G540 and a 400Hz / 24K RPM spindle I get the following with my pulley set to min=0 and max=24000, ratio=1

M3S6000 / 188Hz on the VFD, It should be 100Hz
S12000 / 256, it should be 200Hz
S18000 / 324, it should be 300Hz
I didn’t try yet S24000 since the spindle is new and will try this speed later

Should I play with the numbers on the Motor Tuning & Setup page to get the right frequency?

47

General Mach Discussion / G540 No PWM Signal

« on: February 05, 2017, 01:29:22 PM »

I have tried various settings to get G540 to output the correct PWM voltage on terminals 7&8 with no success. (The 4 stepper motors work fine).

The first time I powered ON my Chinese VFD it was programmed for local control and the spindle started at very low RPM. Turning the speed knob had no effect on the spindle speed (spindle is water cooled and I can hear the VFD powered ON the water pump). But when I switched ON the power to the G540 it went to full speed in a second and I turned it OFF with my Estop to avoid damaging the spindle.

Reading on the web, someone suggested to first check the voltage on the G540 terminals 7&8. Doing that (with the wiring to VFD disconnected) I get between 0.09 – 0.12vdc with speeds M3S6000 to M3S24000) Changing the Mach3 settings to various combinations including the pulley settings from 0-24K and other combinations, the volts remain the same.

I used the Gecko 540BVFD.XML but now it has changed because of the various new settings regarding motor outputs, output signals and motor tuning but under Spindle setup on Mach3 I left the default settings in the motor control (Use Spindle Motor Control and PWM Control are checked, PWM Base Freq. = 50, Minimum PWM = 5%)

The G540 terminal 5 is connected the VFD FOR (terminal 6 is not connected to anything)
Terminals 7, 8, 9, ARE connected to VFD ACM, VI and +10V respectively
The water pump is connected to VFD terminals FA & FB (pump works fine)
The G540 terminal 12 is connected to VFD DCM plus to earth ground plus to the PSU negative (all separate wires).

Any ideas for help?

48

General Mach Discussion / Change Wiring

« on: February 04, 2017, 01:58:44 PM »

My setup with the G540 is all complete and works fine but the motors direction is not the way I wanted. Like when I press the page UP keyboard button the Z axis goes down. I know I can change the Active Low from green to red or from red to green or perhaps from the Homing / Limits page click on the Reverse column? 

It’s also easy for me to switch the motor wiring but I don’t know which pair. From the attached Keling wiring schematic which pair of wires will change the motor direction?

49

General Mach Discussion / G540 Steps Per

« on: January 28, 2017, 11:31:24 AM »

I got a new G540 and using the .XML from Gecko (540BVFD) the steps per setting is 20000 which makes my motor running very rough. Using the Mach3 “Set Steps per unit” on the Settings tab it gives me a steps per of 4002 which is pretty close to what I get with my calculations assuming a 1/8 microstepping. (my cals: 200 x 8 x 2.54 = 4064 with 10mm Lead ball screws)

What microsteps the G540 is using and can I change them?

50

General Mach Discussion / General Config “Charge Pump ON in Estop”

« on: July 25, 2016, 12:14:09 PM »

What really happens when I check the “Charge Pump ON in Estop” in the General Config?

Pressing my Estop disables all outputs regardless if my BOB includes a SCHP circuitry?