Centroid Acorn CNC User manual

Centroid AcornCNC Plasma Installation Manual
CNC Software version: CNC12 v4.66+
Models: AcornCNC and Centroid THC
2
3
www.centroidcnc.com
Plasma G-code Introduction
Acorn and THC Bench Test
Acorn CNC Plasma Installation Manual Copyright © 2022 CENTROID
AcornCNC Plasma
1
Installation Steps Overview
6
20
4
25
34
21
Test Fire Torch
Arc Voltage Calibration Procedure
Machine Homing Methods
Plasma G and M codes
Plasma G code Smoothing
Operator Control Panel
Plasma Machine Sweet Spot
8
THC TX and RX Mounting Guidelines
9
Torch Touch O󰀨 Types and Conguration
37
Plasma Wireless Control Pendant 40
Appendix 42
23
Material Prole Manager
THC RX and TX Specications 48
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Overview: Centroid Acorn Plasma CNC controller etup and Commissioning teps
Perform these setup tasks in order.
1.) Acorn Bench Test and then the THC kit Bench Test. It is imperative to bench test both the Acorn and the THC
boards (R and T ) Before installing in a cabinet or hooking up to the Plasma Unit.
2.) CNC control wiring and configuration using the Acorn Wizard.
(See the Acorn Installation manual for non plasma related wiring and configuration such as axis motor drive wiring
and setup, overall turns ratio, homing options etc.
https://www.centroidcnc.com/centroid_diy/downloads/acorn_documentation/centroid_acorn_install_manual.pdf
If using open loop stepper motors it is imperative that the motor,drive and power supply be matched/balanced and
configured properly. Be sure to follow the guidance found here from GeckoDrive.
https://www.geckodrive.com/support/step-motor-basics.html
It is imperative that the mechanical design of the machine operates in the 1 to 2 turns of the axis motor yields 1” of
travel on the and Y axes. Direct ‘Axis motor to Rack Pinion’ driven machines do not provide the best cutting
results. A gear box or belt reduction is highly recommended on rack driven machines so one rotation of the axis
motor will result in at least 1” of axis travel. Typical gear box ratios used on rack drive Plasma machines are 5:1 and
3:1. ( which one you use depends on the pinion diameter being used).
Ensure Machine design is in the “Plasma Sweet Spot” before proceeding.
3.) Choose Torch Touch off Method and follow THC Wiring and Plasma specific setup information in this document.
4.) Verify Torch Touch Off and Breakaway functionality
5.) Verify basic torch function with the Torch Test Fire button on the VCP.
6.) Load a Profile using the Centroid Profile manager to select a Profile to match the material to test cut with.
7.) Run the Arc Voltage Calibration macro.
8.) Load and cut the Centroid test plate plasma G code program to verify operation.
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Introduction: Centroid Plasma G code programs are designed to be used in conjunction with a material profile. A
material profile is a set of Plasma CNC values for a particular torch type/amperage and material type and thickness.
The G code program that defines the geometry itself does not contain these values managed by the Profile manager
such as pierce height, target voltage, cut height etc.. this information is provided by the material profile. This
method of separating Geometry from Plasma settings provides advantages such as the ability to quickly change
plasma related setting without having to go back to the CAD/CAM system to generate a new G code program and
allows the same G code program to run with any material profile. One G code program for any material thickness or
type.
Below is an example of a typical Centroid Plasma G code program
(this G code was created with SheetCam, the Centroid Plasma sheet cam post processor is available for download
here ) .
;Filename: bear_23x23.tap
;Post processor: centroid_plasma_thc_sheetcam.scpost
;Date: 1-21-2022
G20 ;Units: Inches
G90 ; Absolute positioning
M65 ; Loads the profile selected in the Profile Manager
;Operation: Inside Offset, Under Bear, T1: 0.060 Steel Plasma
G0 10.3078 Y7.1462
M61 ; Performs Torch Touch off and Pierce Cycle
G2 10.4878 Y7.166 I0.0998 J-0.0801
G1 10.763 Y6.9451
G1 10.314 Y6.9368
G3 10.1121 Y7.1204 I-0.3355 J-0.1661
G3 10.1095 Y7.1213 I-0.0105 J-0.0276
G3 10.0053 Y7.1233 I-0.0561 J-0.2024
G3 10.0012 Y7.1221 I0.0068 J-0.0288
G2 9.896 Y7.1735 I-0.0291 J0.0739
G1 9.8954 Y7.1751
G2 9.8817 Y7.2354 I0.2442 J0.0875
G1 9.8816 Y7.2362
G2 9.8802 Y7.2819 I0.2124 J0.0289
G2 9.9898 Y7.6885 I1.2866 J-0.1287
G2 10.0437 Y7.7657 I0.2517 J-0.1182
G3 10.0453 Y7.7675 I-0.021 J0.0208
G2 10.0986 Y7.7702 I0.0279 J-0.0234
G1 10.0995 Y7.7694
G2 10.1288 Y7.7344 I-0.1061 J-0.1184
G1 10.141 Y7.7133
G3 10.2179 Y7.4412 I1.6518 J0.3199
G3 10.2818 Y7.3269 I0.4091 J0.1538
G3 10.3452 Y7.2803 I0.114 J0.0889
G1 10.4878 Y7.166
G2 10.5075 Y6.986 I-0.0801 J-0.0998
M62 ; Performs Torch End Cycle
As you can see the Geometry of the plasma cuts consist of G1, G2 and G3’s with no feed rate and no Z values.
( Note: This example program is included with the CNC12 Plasma software installation and can be found by
pressing F2 LOAD from the main screen of CNC12. )
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Centroid Acorn Plasma etup and Configuration
1.) Acorn Bench Test. Follow the bench test procedure found here.
https://www.centroidcnc.com/centroid_diy/acorn_quick_start_guide.html
CNC12 Plasma Beta Software Download is here.
https://centroidcncforum.com/viewtopic.php?f=65&t=6950
Please review the requirements follow the bench test procedure to the letter.
Highlights not to be overlooked.
- CNC PC requirements especially the SINGLE CORE benchmark requirements. (this does not mean you
have to use a single core CPU (which is impossible to find these days anyways) The single core bench mark of 1500
is the performance rating of ONE of the cores of the CPU, NOT the overall score (combined core performance).
- use a 1920x1080 display resolution
- properly preparing Windows 10/11 for CNC PC use. Imperative that these guidelines are followed.
Perform the R an T Bench Test after following the Acorn Bench Test procedure.
Bench Test the Centroid THC kit with the Acorn, follow schematic # 15121 and hook up the TX and RX
board. Do not connect to Plasma unit at this time.
https://www.centroidcnc.com/centroid_diy/schematics/pbrowse.php#
https://www.centroidcnc.com/dealersupport/schematics/uploads/S15121.r2.pdf
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Once the THC boards have been setup in bench test configuration, be sure to Set the THC Installed selection in the
THC configuration menu to “YES”. Found in the Profile Manager.
THC RX and TX Voltage ignal Communication Bench Test
Now Connect a DC power source such as a Battery or Lab Supply to the T board.
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Or use a Lab Power supply.
Verify with a Volt meter that the supplied voltage is actually at the T board terminals.
Then run the “THC_Benchtest.cnc” T to CNC12 Voltage signal communication Test Macro.
1.) Home CNC12 by pressing cycle start button.
2.) Press F2 Load and navigate to “THC_Benchtest.cnc”
3.) Press Cycle Start to run the “THC_Benchtest.cnc” macro
4.) The test macro will report the Voltage that CNC12 is measuring with a message on the screen.
Once the test voltage signal has been verified by the macro, power down and continue with the installation.
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2.) Once the bench tests has been performed its time to install, setup and configure the YZ axes to get basic CNC
motion.
See Acorn Installation manual for non plasma related wiring and configuration such as axis motor drive wiring and
setup, overall turns ratio, homing options etc.
https://www.centroidcnc.com/centroid_diy/downloads/acorn_documentation/centroid_acorn_install_manual.pdf
Important details for good Plasma machine performance not to be overlooked.
- When using open loop stepper motors it is imperative that the motor, drive and power supply be matched/balanced
and configured properly. Just because it runs doesn’t mean it is configured properly for best performance. Be sure
to follow the guidance found here from GeckoDrive. https://www.geckodrive.com/support/step-motor-basics.html
Better yet, use any of the affordable Closed Loop Stepper or AC motor/drive packages now available. There is
really no real cost savings in using open loop steppers any more and the performance advantages of closed loop is
tremendous in operational time savings and machine performance. (better smoother cuts with less waste/mistakes).
- The ‘sweet spot’ for Plasma Table mechanical design is so that the machine operates anywhere in the range of 1 to
2 turns of the axis motor yields 1” of travel for the and Y axes. Direct Axis motor to Rack Pinion driven machines
do not provide the best cutting results. A gear box or belt reduction is highly recommended on rack driven machines
so one rotation of the axis motor will result in a least 1” of axis travel, more is better. Arrange the mechanicals to be
in the 1 to 2 inch of travel per one revolution of the Axis Motor. Typical gear box/belt reduction ratios used on rack
drive Plasma machines are 5:1 and 3:1 which one you use depends on the pinion diameter being used.
- If you are coming from Mach, LinuxCNC or other DIY cnc controllers be sure to set Acorn ‘steps per rev’ and the
‘overall turns ratio’ properly..see this post
- Plasma Table Z axis Overall turns ratio is ideal at 2.5 turns per inch. Range for good performance 2.5 to 5 turns
per inch. Note: More reduction results in slower Z axis max rate. 5 turns per inch (a common ballscrew pitch is
5mm which = 5.08 turns per inch) can be used just be sure to have a Z axis motor that has the RPM and power
rating to operate the Z axis at least 500 ipm reliably. Highly recommend a Closed Loop motor/drive on the Z axis of
a Plasma machine.
- AC servos on all axis are the best solution. If budget is a consideration use Closed Loop Stepper motors. At this
day and age it is really not cost effective to use open loop stepper motors any more, but if you insist at least install a
Closed Loop Stepper on the Z axis. Like this. https://www.automationtechnologiesinc.com/products-page/nema34-
closed-loop-stepper-motor-system-hybrid-servo-kit/nema-34-hybrid-servo-motor-kl34-8n-1000-rated-torque-1128-oz-
in
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The Plasma Machine etup weet pot for nice cuts and smooth action.
Mechanical Sweet Spot.
1.) Overall Turns ratio value in the range of 1 to 2 turns of the axis motor per inch. Mechanically build the machine
so that one turn of the axis motor yields 1” of travel (25mm) or less. All rack and pinion driven machines will require
a belt reduction or gear box to achieve this. Typically in the 3:1 to 5:1 range depending on the rack and pinion
chosen. Note: Direct driving the pinion with the axis motor results in poor cuts. Z axis Overall turns ratio sweet spot
is in the range of 2.5 to 5 turns per inch.
2.) Motors sized properly to move the machine without risking losing steps or stalling.
3.) Free and easy axis motion with no sticky spots or other problems, when the axis motor is disconnected moving
the axis back and forth by hand should be smooth, consistent and easy.
4.) Machine is rigid enough not to shake or flex when moving at typical cutting speeds.
Electronic sweet spot
1.) Steps per rev set in the 1600 to 3200 range for stepper motors. Both the Acorn Wizard and the Stepper drive
should be set to at least 1600 steps per revolution. 2000 is a good steps per rev value to use. Do not use values
below 1600.
2.) Stepper motors are required to have proper matching power supplies and AMP settings on the stepper drive. Just
because the motor works does not mean that it has been optimized for smoothness. No amount of Centroid G code
smoothing will overcome a stepper motor that has too many amps being pumped into it or has its phases not wired
properly for the voltage of the drive power supply being used. Review https://www.geckodrive.com/support/step-
motor-basics.html for details. Better yet use AC brushless servo motors (Clearpath, Estun, Delta etc) or closed loop
stepper motors (Leadshine, Stepper Online) instead of open loop stepper motors.
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Machine Homing: Two philosophies, Chose to use a ‘machine home position’ or not. See below for pros and cons
of each method.
To home or not to home: The Centroid Plasma CNC controller can be run in main two modes.
1.) A machine coordinate system is employed. This method requires that a type of machine homing be used.
2.) No machine coordinate system is used, only a local “temporary” part zero location. This method does not require
any sort of machine homing.
Each method has its advantages and which one you choose depends on the machine and how it is being used and
often boils down to personal preference. The Centroid CNC controller supports either method.
Advantages of #1
- CNC controller will ‘remember’ Part Zero Locations when powered on and off.
- CNC controller can use ‘soft travel limits’ to avoid crashes
- CNC controller will inform the user before running a job if that job is going to fit within the work envelope based on
the part zero location.
- Homing can be automatic using switches or done semi automatic (user simply jogs or pushes machine to home
position (usually to marks on the machine or urethane hard stops)) to set home position.
- The Reset Home button on the VCP will reset the home position after a loss of steps event when using open loop
steppers
- Auto squaring of Gantry can be used or semi auto squaring (semi auto = push gantry against hard stops before
homing)
- A predefined Torch Tip Change location can be used along with the “Torch Check” button on the VCP.
Cons of #1
- some view homing as an extra step before the machine can be used to cut a part.
- If the machine is constantly losing steps, having to re-home after loss of steps event when using open loop
steppers is viewed by some to be a pain and unnecessary step when the advantages listed above are not important.
- some are confused by the use of two coordinate systems: Machine Coordinates and Work Coordinates and how
the are used together when using this method.
Advantages of #2
- To some using only the Work Coordinate System (WCS) is simpler way of doing things.
- You never have to home the machine.
Cons of #2
- Loss of the advantages of #1. For example: if commanded to move 100 inches even if there is not 100 inches of
travel the machine will do it and crash. Example 2: If part is too large for work envelope of the machine or the part
zero location is set at a position that where the part won’t fit the machine just runs the part until it crashes creating
wasted material.
- Gantry should be square before power up of machine so paired motors lock the gantry in the square position when
powered up. If you forget or if the gantry gets knocked out of square while running you have to power cycle the
machine to get it square.
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Choose the type of Homing in the Wizard Homing and Travel menu.
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TX and RX Board mounting guidelines.
- The Centroid THC supports only Plasma Units with divided voltage output.
- The T board MUST be powered with a separate 24 volt power supply
Follow the Hookup schematics and use the meanwell 24 volt provided with the Acorn THC kit.
Search “plasma” to see all the Acorn plasma schematics.
https://www.centroidcnc.com/centroid_diy/schematics/pbrowse.php#
- Mount the T board as far away from any other components in the cabinet. One of the T ’s jobs is to
isolate any possible Plasma Unit voltage noise/leak/EMI etc so, if that happens it does not destroy the R
board or the Acorn or any other components.
- Run any wires from the Plasma Unit, Torch Head or machine as far apart from any other control related
wires to isolate them from other wires and components.
- The Plasma Unit’s positive divider voltage is referenced to THC T GND, see schematic.
- The Plasma Unit’s negative divider voltage connects to the THC T ANLV connection.
(ANLV = Analog Low Voltage)
- Do Not bend the fiber optic cable tighter than a 2 inch radius. Do not pull on the black fiber part of the
fiber optic cable to remove or insert into socket. Hold the Plastic end to insert or remove the fiber from the
socket on the T and R boards.
- Follow good wiring and ground practices to avoid ground loops. Verify Plasma Unit Clamp and T GND
are same with a good low ohm continuity with an ohm meter.
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3.) Choose Torch Touch off Method.
Centroid Acorn Plasma support several common Torch Touch Off methods.
a.) The conductive Torch Tip is used as the sole method of touch off. (either a straight connection or with a stand
alone Ohmic sensor box can be used. ) see schematic #15107 all Acorn schematics are here.
https://www.centroidcnc.com/centroid_diy/schematics/pbrowse.php#
b.) A Float Switch is used as the sole method of touch off. see schematic #15109
c.) The conductive Torch Tip is used in conjunction with a Float switch. see schematic #15108
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Torch Mounts: Floating heads, Magnetic breakaway and Round Mounts are all supported.
Magnetic Breakaway Torch Mounts.
Magnetic Breakaway combined with a sliding head (Floating Head) is a good choice. This setup provides good
protection with accurate Floating Head Torch touch off performance. This torch mount set up can also be used in
conjunction with ohmic/conductive touch off. Photo on left shows Magnetic Breakaway mount used with
ohmic/conductive touch off and the photo on the right shows a magnetic mount with a Floating Head Torch Touch
Off.
Magnetic Breakaway with Floating Head Touch Off
and Ohmic/Conductive Touch Off
Magnetic Breakaway with Ohmic/Conductive Touch Off
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Round Mounts
Round Mounts are a crude kinematic seat that lifts and pivots in YZ
when the torch touches anything.
Round Mounts come in two flavors:
1.) a two sensor Round Mount and 2.) a three sensor Round Mount.
Most Round Mounts perform can two functions: Torch crash protection
(Breakaway), and as a “Float Switch” Torch touch off sensor.
Round Mounts typically employ Proximity Sensors as the switches.
Proximity Sensors also come in several flavors, make sure the round
mount has NPN NC prox switches. The Acorn Plasma system requires
NPN NC proximity sensors. (PNP will not work)
Round Mounts can be used to act solely as torch breakaway sensor to
let the CNC controller know that the torch has hit something. In this
case the all the sensors can be wired in series and connected to the
Torch Breakaway input.
Round Mount heads can also be set up so that one of the proximity
switches performs the Torch “Float Switch” duties and the others are
used as Torch “Breakaway” sensors.
Note: Sometimes getting the cheap made in china round mounts to trigger properly will require a bit of trail and error
adjustment and sometimes will require modifying the unit to get it to perform as intended.
For Round Mounts that have three sensors, often two of them are used as the Breakaway sensors and the third is
the Torch Float switch. In this case simply wire the two breakaway proximity switches in series as seen in the Round
Mount schematics.
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Ohmic and Conductive Torch Touch Off.
The “T in” screw terminal on the THC T board is dedicated for conductive/ohmic touch off.
By design the “T in” terminal on the T board is intended to be used with the Torch Conductive Tip. This conductive
torch tip connection can be used with or without a separate stand alone Ohmic sensor box. By definition the T in
connection on the T board is CNC12/Acorn Input 9. No need to define an input assignment to input 9 (you won’t
see it in the Wizard Input Definitions menu) as input 9 is only used for conductive Torch Touch Off.
Green LED = Conductive tip is grounded
Red LED = Conductive torch tip is not touching anything.
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For Method a. A Float witch is used as the sole method of touch off:
Wire Conductive Torch Tip according to schematic #S15107
In the Torch Touch Off configuration menu, set “Is a Float Switch being used in conjunction with Torch Tip Touch off?”
to No. the rest of the setting and questions in this menu. then do not apply so no need to set them one way or the
other, they are ignored.
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Method b. Set Wizard Torch Float Switch input definition to Input Two.
Then Choose “No” to “Is a Float Switch being used in conjunction with Torch Tip Touch Off?
Set the Distance between Float switch trigger and torch tip touch in inches (or mm)
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For Method c. Wire the Float Switch to input #2. See Schematic # 15108
Use the Acorn Plasma Wizard Input definition menu to let CNC12 know which Acorn input is being used for the Float
Switch, click and drag “TorchFloatSwitch” to Input #2.
CNC12 needs to know which switch triggered first so set the “Before and After” slider to indicate if the Float Switch
triggers before the Torch Tip touches the metal of after the Torch Tip touches the metal.
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Is a Float Switch being used in conjunction with Torch Tip Touch Off?:
Yes= Both the conductive torch tip and float switch are being used.
No= either a Float or a Conductive is being used just not together.
Float Switch input state when triggered: Does the switch Open or Close when triggered?
Does the Float switch trigger before or after the Torch Tip touches surface?
Distance between Float switch trigger and torch tip touch in inches (or mm)
The Acorn Plasma Torch Touch off menu supports several typical touch off setups.
1.) Torch Tip alone
2.) Float Switch alone
3.) Float Switch with Breakaway safety switch
4.) Torch Tip with Breakaway safety switch
5.) Torch Tip with Float Switch and Breakaway safety switch
6.) Torch Tip with Float Switch
The Float switch trigger position can be either above, below or even with the Torch Tip.
Use the Acorn Wizard Input menu to define which input numbers to use for the Float Switch and the Torch
Safety Breakaway switch connections. The Torch Tip on the THC T board is always input #9 and can not
be changed. The inputs being utilized for Torch Tip, Float Switch and the Breakaway switch are echo’d
below.
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Acorn Wizard Input Menu
Note:
the
Float
The “TorchFloatSwitch” input is also monitored by CNC12 when not running a touch off cycle so that it also
acts as a breakaway switch. In other words is the Float Switch is triggered unexpectedly (while not in a
touch off cycle) CNC12 will stop and issue a Breakaway error message.
THC hookup schematics are here. https://www.centroidcnc.com/centroid_diy/schematics/pbrowse.php|
Click Search Files type button and type in “plasma”
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