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Topics - ggallant571

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General Discussion / inkscape export
« on: January 18, 2017, 05:12:01 PM »
I have some files in svg format that I would like to convert to dxf. I open and display the files ok in Inkscape 0.91. Then I save as "dxf". The files get saved but the units are off. 10mm  exports as 2.82mm. The ratio is 3.54 which I recall is the pixel to mm at some standard ppi.

General Discussion / First Slate Etch
« on: January 08, 2017, 05:52:34 PM »
Tried my first etching in slate. Not very good compared to wood. Tried to etch the picture of a tigers head, assume I got it from this forum. The lines are nice and crisp but the texture of the hair came out all flat. I suspect it was a poor example to start with.

Going to try Agastar's Elf with text.

Is there a way to clean (sand) the slate so it can be reused? At least for test pattern.

Alternative Applications & Firmware / STM32F303K8
« on: January 08, 2017, 01:59:46 PM »
I purchased a low cost STM32F303K8 Nucleo board in the AVR Nano form factor. Ported my home brew gcode firmware. After a week of setbacks it is working. No visible difference in results from the AVR but the processing speed (72MHz) and the extra RAM (12KB) make for a more comfortable processing environment.

Have started to do some performance measurements. I currently drive the stepper motor update at 40HKz (25 usec). The AVR uses about 14usec and the ST about 6usec. Starting to instrument the time it takes to process a single G01 Yyy.yyy command. The AVR was about 1.6msec with the processor idle which goes to about 4msec when actively etching.

If you are wondering if this matters the answer is probably NO for cutting and YES for etching. The faster the processing the shorter the individual etch segments can get. User Beikeland posted an interesting unit (mm/hz) that I want to investigate.

I still need to find the magic recipe to enable hardware floating point.

General Discussion / Killing a A4998 stepper motor driver
« on: January 05, 2017, 08:07:15 AM »
I killed a A4988 driver last night. Was playing with new software and had the current limit on the bench supply set quite low, probably less that 0.5A. The X played ok but the Y which drives two motors just consumed all the current the bench supply could deliver causing the voltage to drop low and very sporadic movement on the Y motors. Few seconds and all stopped. Do not know if the bench supply caused random surges but the module is quite dead. Set current limit at 2A and a new A4988 works as expected.

General Discussion / Benbox laser Messages
« on: December 14, 2016, 01:22:31 PM »
I am wondering about the behavior of messages in "My Messages". From some users I get a email and not from others. Is this something that the sender selects or I need to configure?

General Discussion / Power & Weak Laser switches
« on: December 05, 2016, 02:32:49 PM »
I am looking for a manufacturer part number for the latching switches used on the Eleks controllers.

General Discussion / SVG Files
« on: November 02, 2016, 05:17:42 PM »
I have been using png files for raster etching operation on my Linux application that utilizes the GTK toolkit. When reading the png file I get the number of channels (3 or 4) that represent the R,G,G,A data channels.

I was converting the RGB into gray scale by averaging the 3 color channels. Then I imported a png that was created in grayscale only where RGB are all zero and the intensity is in the A channel.

Note: If there are only 3 channels then it must be RGB.

Both are fine except I don't know how to determine which one is really there. So far I scan the A channels looking to see it they are all 0xFF. If so then calculate the grey from RGB. Or I can scan all the RGB channels for all 0xFF or 0x00 and use the A channel. Problem is what if there is info in both RGB & A or is that an invalid condition?

An acceptable alternative would be a utility that rewrites the file as grayscale only.

General Discussion / Connecting to forum
« on: October 28, 2016, 09:04:50 AM »
I have a Windows 10 laptop that will not login into this forum. Getting:


You don't have permissions to access /index/php on this server.
Additionally, a Forbidden error was encountered ..................

This laptop just went thru a Microsoft auto update. Able to login on 3 other machines, 1 Win 10, 2 Linux. Have rebooted and reset password (to existing) via this computer.

General Discussion / Option to read new messages
« on: October 13, 2016, 09:38:21 PM »
I had to kill Google Chrome, not due to benboxlaser, and when it came back I no longer have the option to display unread messages. 

Alternative Applications & Firmware / DLCM
« on: October 12, 2016, 12:05:32 PM »
Ralph, our friendly admin, has kindly added this forum entry for comments regarding Linux software applications in general and my Diode Laser Command Module (DLCM) in specific. I am not interested in competing with T2Laser or BCL and have absolutely no interest in providing long term support but I do use Linux as my primary development system and have a somewhat working application.

My work flow for cutting has been to design in OpenScad and export to a 2D SVG file. This is primitive straight lines only, no arcs.

For etching I load png or jpg files. Etching is nowhere close in quality to T2Laser.

Cutting / BCL dfx file
« on: October 07, 2016, 07:56:57 PM »
My first attempt at using BCL with my own design file fails with error message:

"Premature end of entity definition"

My work path is openScad 3d design projected onto a 2D image and exported to either SVG or DFX. Up to now it has been svg and the cutting application was home brew on Linux. Loaded BCL 1.52 on a Windows 10 laptop and her I be.
dfx file attached. BTW, the dfx file opens ok with LibreOffice on Windows.

General Discussion / Image Testing Material
« on: October 05, 2016, 06:02:28 PM »
I have been doing a lot of laser related firmware and host software. Had been using 3mm (1/8 ") craft plywood for testing. Started using white printer paper but not very useful for etching. Today I bought a package of 4x6 inch blank Neon index cards at Walmart for around $0.88. They are great. Low power cuts the top color layer and exposes the inner cardboard.

I am running a 5.5W laser at 10% power and 900 mm/min feed rate. A lot cheaper, easier to use, and quicker.

General Discussion / XON/XOFF with USB
« on: September 22, 2016, 08:05:39 PM »
I am rolling my own firmware for the Nano geared towards just low power laser units. Been working OK for a few days while cutting. Switched to engraving mode and think there is data corruption when running at a high feed rates.

Small images complete as expected. Zax provided a test image of a cow and that causes grief after a few minutes of etching.

The host software counts the number of outstanding "ok/error" responses and throttles the new messages accordingly. Wondering if adding XON/XOFF to the serial stream would help. With a traditional serial UART mechanism I know we need to account for data queued in the hardware. With USB I expected the amount of buffered data to be much larger.

The stock grbl code does not enable XON/XOFF. It is a compile time option.

I can increase the receive buffer size in the Nano by a small amount and am looking at the code to free more. Just do not know what the stack requirements are (or even how to measure) so I really don't know the upper limit on RAM usage is. I have a Verilog model of the AVR CPU instruction execution unit (no peripherals) that would allow detailed examination but that is another sink hole to drown in.

Thoughts, hints, suggestions would be appreciated.

General Discussion / Corrupt EEPROM
« on: September 14, 2016, 01:55:10 PM »
The EEPROM in one of my Nano's is corrupt. Anyone know the magic sequence to restore. Right now it spends a long time waiting for an "ok" after issuing a "$$" command. Then it spews a ton of register settings.

Cutting / Slightly odd behavior when cutting triangles
« on: September 07, 2016, 09:09:20 PM »
Attached is a small gcode file that cuts two triangles with x & y set at 20mm. The difference is the order in which the cuts are taken. On my machine they are different. There appears to be a 1mm error.

Test was performed with GrblController and Grbl 09j firmware. Firmware was modified to support 100% pwd at S100 so the cuts are at 20% power (if power is linear).

I would appreciate it if someone else could either duplicate or assert that it is just me.


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