Justin Log 2013 - Revision history

Marcin: Marcin moved page Justin Log to Justin Log 2013 without leaving a redirect

2019-09-11T16:46:50Z

Marcin moved page Justin Log to Justin Log 2013 without leaving a redirect

← Older revision	Revision as of 16:46, 11 September 2019
(No difference)

Marcin: /* Sat May 18, 2013 */

2016-01-24T13:45:53Z

Sat May 18, 2013

← Older revision		Revision as of 13:45, 24 January 2016
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	[[Category:Logs]][[Category:CNC Torch~~/Router~~ Table]].		[[Category:Logs]][[Category:CNC Torch Table]].

Marcin: /* Sat May 18, 2013 */

2016-01-24T13:45:41Z

Sat May 18, 2013

← Older revision		Revision as of 13:45, 24 January 2016
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	Spent a good day designing [[Bobcat Standard Quick Attach for LifeTrac]] during OSE Design Sprint.		Spent a good day designing [[Bobcat Standard Quick Attach for LifeTrac]] during OSE Design Sprint.


			[[Category:Logs]][[Category:CNC Torch/Router Table]].

IEF RD: /* Mechanical */

2013-07-20T13:29:35Z

Mechanical

← Older revision		Revision as of 13:29, 20 July 2013
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	==Mechanical==		==Mechanical==
	Direct drive to threaded rod ~~figure steps~~ to ~~height~~ to compute sample rate. Needs one stepper motor for z could use another for angle rotation.		Direct drive to threaded rod, Thread pitch/step pitch/minimum xy step needs to be computed in regards to compute sample rate for height sensor. Needs one stepper motor for z could use another for angle rotation. Most systems just use some extruded track material and a antibacklash nut to control height. Make sure it can accommodate Oxy and plasma torch head.

	=Sat Jun 22, 2013=		=Sat Jun 22, 2013=

IEF RD at 13:24, 20 July 2013

2013-07-20T13:24:58Z

← Older revision		Revision as of 13:24, 20 July 2013
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	2V/4.88mv resolution gives 0-409 range or .244V resolution from the plasma torch or theoretically 3 mill this should be fine.		2V/4.88mv resolution gives 0-409 range or .244V resolution from the plasma torch or theoretically 3 mill this should be fine.

			3.'''Event monitoring'''- needed to monitor crash/limit switches and also torch control variables, if the torch slows down as in a curve the voltage will rise and cause a erroneous lower of the torch. These conditions need to be addressed in software.

			===Links===
			http://www.everlastgenerators.com/downloads/PowerPlasma%202013.pdf

			http://www.candcnc.com/PDF/LCTHC-Manual_REV8.pdf

			Possible systems

			http://www.candcnc.com/LCTHC.html


	===Software integration grbl===		===Software integration grbl===
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	3.'''Event monitoring'''- needed to monitor crash/limit switches and also torch control variables, if the torch slows down as in a curve the voltage will rise and cause a erroneous lower of the torch. These conditions need to be addressed in software.

	~~===Links===~~
	~~http://www.everlastgenerators.com/downloads/PowerPlasma%202013.pdf~~

	~~http://www.candcnc.com/PDF/LCTHC-Manual_REV8.pdf~~

	~~Possible systems~~

	~~http://www.candcnc.com/LCTHC.html~~

IEF RD at 13:23, 20 July 2013

2013-07-20T13:23:05Z

← Older revision		Revision as of 13:23, 20 July 2013
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	This can be measured by a a/d on a microcontrol but needs to be isolated first. The sample rate should allow a A/D reading every .5 second.		This can be measured by a a/d on a microcontrol but needs to be isolated first. The sample rate should allow a A/D reading every .5 second.

	The Atmega1280/328 sample rate for a A/D is 14 clock cycles the A/D has a internal clock that should be set to the lowest sample rate of 50KHZ this will help with noise and give a more accurate reading. It seems like a half second latency is the cutoff for sensing and correcting at 25KHZ 14 clocks would give 1785 samples, to deal with noise probably 50 samples should be averaged. 10 bit resolution gives a 1023/AVcc if a 5v system is used that gives 4.88mV resolution.		The Atmega1280/328 sample rate for a A/D is 14 clock cycles the A/D has a internal clock that should be set to the lowest sample rate of 50KHZ this will help with noise and give a more accurate reading, also as many IO ports as possible should be in High Z to ensure better reading. It seems like a half second latency is the cutoff for sensing and correcting at 25KHZ 14 clocks would give 1785 samples, to deal with noise probably 50 samples should be averaged, most commercial systems are claiming a 6Khz sample rate. 10 bit resolution gives a 1023/AVcc if a 5v system is used that gives 4.88mV resolution.

	1023/5AVcc = 4.88mV resolution		1023/5AVcc = 4.88mV resolution
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	2V/4.88mv resolution gives 0-409 range or .244V resolution from the plasma torch or theoretically 3 mill this should be fine.		2V/4.88mv resolution gives 0-409 range or .244V resolution from the plasma torch or theoretically 3 mill this should be fine.

	''Use with grbl'' The G~~-code/stepper driver~~ code ~~running on~~ the ~~Atmega utilizes~~ the fixed timer1 interrupt (TIMER1_COMPA_vect) to pulse I ~~think there~~ will ~~be latency issues~~.		===Software integration grbl===
			''Use with grbl'' The G code is parsed from serial input checked for exclusivity in command structure then parsed into a block which is stored in a ring buffer the ring buffer is read out one command at a time utilizing the fixed timer1 interrupt (TIMER1_COMPA_vect) to run the pulse event and timer2 compare to clear the stepper port I/O. They use different motion envelopes to interpolate speed/distance with each command.

			''Integrating a THC''- To integrate the torch height controller four components would need to be integrated (limit switch, z axis motor control, two height/ A/D sensors and G-code parsing for a M command). Since grbl already controls the z axis in software a new block could be designed for each stage of torch setup, touch off, piercing, cut ect. The problem will come from integrating the sensors into the program flow grbl is right now a event driven machine either from a serial event or then a timing event to control the the rest of the control structure.

			Since the THC is only a specific process for plasma and oxy-fuel cutting I recommend developing a second board to run the sampling and motion control for the z axis while using a plasma cutter this will avoid the problems of:

			Latency caused by a conflict with the A/D sample rate and the stepper pulse train. This will decouple the sample rate from the timed execution cycle of grbl.

			I/O for future iterations if height and angle are desired as in some commercial applications along with limit switches and sensors the available I/O might get in short supply depending on which Atmel chip is used.

			To keep grbl a lightweight targeted code base development of code to run on a separate processor would in my opinion keep the code base cleaner, instead of writing a bunch of exceptions for new timing models.

	~~I recommend a separate processor for height control.~~

	===Use with oxy torch===		===Use with oxy torch===

IEF RD: /* Mechanical */

2013-07-18T03:10:15Z

Mechanical

← Older revision		Revision as of 03:10, 18 July 2013
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	==Mechanical==		==Mechanical==
	~~The same rack and pinion track should be used with direct~~ drive ~~off the~~ stepper motor for ~~maximum speed and resolution~~.		Direct drive to threaded rod figure steps to height to compute sample rate. Needs one stepper motor for z could use another for angle rotation.

	=Sat Jun 22, 2013=		=Sat Jun 22, 2013=

IEF RD at 02:26, 18 July 2013

2013-07-18T02:26:54Z

← Older revision		Revision as of 02:26, 18 July 2013
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	=Wed jul 17 2013=		=Wed jul 17 2013=
	Cnc torch table notes		'''Cnc torch table notes'''

	==Height control==		==Height control==

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	and		and

	Qprox: http://media.digikey.com/pdf/Data%20Sheets/Quantum%20PDFs/Qt160_07.pdf		Qprox: http://media.digikey.com/pdf/Data%20Sheets/Quantum%20PDFs/Qt160_07.pdf

	These provide baseline sampling compensation so they act like a switch more than a sensor but for the initial height sensing I think they would work well.		These provide baseline sampling compensation so they act like a switch more than a sensor but for the initial height sensing I think they would work well.
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	http://www.agelkom.com.tr/prod02.htm		http://www.agelkom.com.tr/prod02.htm

			http://www.youtube.com/watch?v=b0TpmfcNzeU

	there is not the same issue of noise so I think it would be feasible to make a capacitive sensor based height controller that could be used in both cases. With the plasma torch the capacitive sensor is used ONLY for touch off then it switches to the voltage sensing for the cutting. The oxy-fuel would use the capacitive sensing throughout the cut at a high sample rate.		there is not the same issue of noise so I think it would be feasible to make a capacitive sensor based height controller that could be used in both cases. With the plasma torch the capacitive sensor is used ONLY for touch off then it switches to the voltage sensing for the cutting. The oxy-fuel would use the capacitive sensing throughout the cut at a high sample rate.
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	3.'''Event monitoring'''- needed to monitor crash/limit switches and also torch control variables, if the torch slows down as in a curve the voltage will rise and cause a erroneous lower of the torch. These conditions need to be addressed in software.		3.'''Event monitoring'''- needed to monitor crash/limit switches and also torch control variables, if the torch slows down as in a curve the voltage will rise and cause a erroneous lower of the torch. These conditions need to be addressed in software.

			===Links===
	==Links==
	http://www.everlastgenerators.com/downloads/PowerPlasma%202013.pdf		http://www.everlastgenerators.com/downloads/PowerPlasma%202013.pdf

Line 59:		Line 61:

	http://www.candcnc.com/LCTHC.html		http://www.candcnc.com/LCTHC.html


			==Mechanical==
			The same rack and pinion track should be used with direct drive off the stepper motor for maximum speed and resolution.

	=Sat Jun 22, 2013=		=Sat Jun 22, 2013=

IEF RD: /* Wed jul 17 2013 */

2013-07-18T01:56:33Z

Wed jul 17 2013

@@ Line 33: / Line 33: @@
 V/4.88mv resolution gives 0-409 range or .244V resolution from the plasma torch or theoretically 3 mill this should be fine.
-.Event monitoring- needed to monitor crash/limit switches and also torch control variables, if the torch slows down as in a curve the voltage will rise and cause a erroneous lower of the torch. These conditions need to be addressed in software.
+''Use with grbl'' The G-code/stepper driver code running on the Atmega utilizes the fixed timer1 interrupt (TIMER1_COMPA_vect) to pulse I think there will be latency issues.
@@ Line 43: / Line 58: @@
 Possible systems
 =Sat Jun 22, 2013=

IEF RD at 01:23, 18 July 2013

2013-07-18T01:23:31Z

← Older revision		Revision as of 01:23, 18 July 2013
Line 1:		Line 1:
			=Wed jul 17 2013=
			Cnc torch table notes
			==Height control==

			===Specs for stable plasma cut===
			Three components to plasma height control:

			1. '''IHS (initial height sensing)'''- this is the touch off height or pierce height for the torch (pierce at 150-200% of the cut height). Capacitive sensors would work best for thin material since a mechanical switch could deflect the material giving a false reading. Two chips I have used for touch screen buttons are:

			freescale: http://www.freescale.com/files/sensors/doc/data_sheet/MPR121.pdf

			and

			Qprox: http://media.digikey.com/pdf/Data%20Sheets/Quantum%20PDFs/Qt160_07.pdf

			These provide baseline sampling compensation so they act like a switch more than a sensor but for the initial height sensing I think they would work well.

			2. '''Cutting height'''- is determined by the plasma torches cutting voltage, since the plasma torch uses constant current a 1% change in voltage (100 to 101 volts) is equal to several thousands (typically .015 or more) of arc gap change. This voltage can be read directly from the plasma torch, most torches have a voltage output (example):

			PowerPlasma 60S
			OCV 200V
			working voltage 88-100
			has outputs for 1/16 or 1/50 which gives a output of about 4V

			This can be measured by a a/d on a microcontrol but needs to be isolated first. The sample rate should allow a A/D reading every .5 second.

			The Atmega1280/328 sample rate for a A/D is 14 clock cycles the A/D has a internal clock that should be set to the lowest sample rate of 50KHZ this will help with noise and give a more accurate reading. It seems like a half second latency is the cutoff for sensing and correcting at 25KHZ 14 clocks would give 1785 samples, to deal with noise probably 50 samples should be averaged. 10 bit resolution gives a 1023/AVcc if a 5v system is used that gives 4.88mV resolution.

			1023/5AVcc = 4.88mV resolution

			100v/50 = 2V output from plasma torch

			2V/4.88mv resolution gives 0-409 range or .244V resolution from the plasma torch or theoretically 3 mill this should be fine.

			3.Event monitoring- needed to monitor crash/limit switches and also torch control variables, if the torch slows down as in a curve the voltage will rise and cause a erroneous lower of the torch. These conditions need to be addressed in software.


			==Links==
			http://www.everlastgenerators.com/downloads/PowerPlasma%202013.pdf

			http://www.candcnc.com/PDF/LCTHC-Manual_REV8.pdf

			Possible systems


	=Sat Jun 22, 2013=		=Sat Jun 22, 2013=
	Did [[3 Inch Wheel Hub]] for tractor wheels, sprockets.		Did [[3 Inch Wheel Hub]] for tractor wheels, sprockets.