2.x for kbob's maker space

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Re: 2.x for kbob's maker space

Postby TLHarrell » Thu May 16, 2013 10:53 pm

I really like that little green "breathing" light there at the end. Pretty cool way to be able to show machine status.
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Time passes.

Postby kbob » Mon Jul 14, 2014 3:18 am

My eighth grade math teacher had covered the clock at the front of the classroom with a cardboard sign that read, "Time passes. Will you?" My dad taught in the same school and was good friends with him. But I digress.

It has been OVER A YEAR since I updated this build log. And I've been working on this laser cutter all that time, and I still don't have it working.

Okay, I bought a 3D printer last May, and that distracted me for about three months. But the real distraction is that I've been writing my own firmware stack from scratch. It's been a blast, but it hasn't actually resulted in a working laser cutter yet.

Recap: I am using an Azteeg X3 as the back end, and I'm using a Raspberry Pi as the front end. The Raspberry Pi is headless, and the laser cutter is accessed over the network.

I have working software to start with a line drawing in a PDF file, convert that to G-Code, convert the G-Code to my own command language, called S-Code, send the S-Code through the USB port to the Azteeg, and the Azteeg can trace the outlines and pulse the laser to cut the lines. That much works.

Things that work. Most of these are new in the last year.
  • Firmware: motor control, laser control, limit switches, E-stop and lid switches, power relays for water, air, high voltage supply.
  • Comms software: hold serial port open, send commands and receive status
  • G-Code interpreter: read G-Code, output S-Code.
  • Monitor app: shows all kinds of firmware state, updates in real time.
  • 110V wiring is done. Relays control water and air pumps and high voltage supply.
  • Shelf for laser power supply constructed.
  • Laser tube is installed and the positive lead is attached.
  • Water pump has been tested.
  • Rubber grommets and vent outlet are attached to the back panel. Vent tubing has been acquired.
  • Alu-Panel skins have been sanded smooth and some panels have been attached.
  • Ammeter and E-Stop switch mounted. E-Stop switch is wired in.

Things that are not done yet:

  • Lots of software/system testing.
  • Wire up laser's negative lead through the ammeter.
  • Wire up the laser power supply's control signals.
  • Permanently attach the laser power supply to the chassis.
  • Attach water tubing to laser.
  • Create a web interface so you don't have to ssh in to the Raspberry Pi. (-:

Today's subproject has been to design and fabricate Mk. 2 of the rear panel. The first one was 3D printed in 7 pieces, and was flimsy and wouldn't stay in place. The second one is on the printer now. I'm making it in 3 main pieces with 8 printed fasteners. When it's finished, I'll post details.

Here is a teaser for the software. This is the monitoring app I mentioned earlier. It runs in a terminal window. The idea is to make it easy to pinpoint why things are disabled.

It would be useful to add an LCD display that just displays the Status, Laser, and Motors lines.

kbmon sample.png
Bob
"If you didn't code it, it will never own you." (-:
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Re: 2.x for kbob's maker space

Postby kbob » Thu Jul 17, 2014 12:01 am

This morning before work, I got the negative lead attached to the laser tube. As Bart suggested, I bound the two together with a thin tinned wire, then I buried it in enough silicone tape that it won't pull apart. (Well, not easily. I tested it with about 3 oz. of force. (-: )

The back panel came out well too. I have photos to post.
Bob
"If you didn't code it, it will never own you." (-:
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Back Panel and Top Panel

Postby kbob » Thu Jul 17, 2014 1:14 am

Here is my second-generation back panel. I 3D printed it in ABS.

IMG_0851.JPG
back panel


The lower center connection is another 110V power plug like the one at center top. The upper right is a USB port with a Wi-Fi adapter.

I printed the panel in three sections. The sections interlock, and they are also held together by plastic pins.

Back Panel Exploded.png
back panel sections


I printed plastic pins in two lengths. The long ones (shown) hold the sections together. The short ones hold the panel tight against the laser cutter's skin.

Screen Shot 2014-07-16 at 5.43.47 PM.png
split pin


This actually worked really well. The panel is stiff enough to plug and unplug the power cords, and it holds together pretty tightly.

IMG_0846.JPG
inside view showing the pins


I had already used this technique to make the top panel. Right now it just has an ammeter. I may add some buttons later, or I may implement manual control through the web interface. For now, there is no manual control.

IMG_0841.JPG
top panel with ammeter


IMG_0842.JPG
top panel, inside view


The big insight I got from this subproject is, when designing complex assemblies for 3D printing, make the fasteners big. Really big, like a child's toy.

I used the neon blue color because it was at hand. But now I sort of like that color scheme. I guess I just have no taste.
Bob
"If you didn't code it, it will never own you." (-:
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Connecting the laser power supply

Postby kbob » Sat Jul 26, 2014 7:15 am

I've been trying to decide how to wire up the laser power supply's control signals. My power supply has six signals. I think it's the same as most. The labels are cryptic; have are my best guesses.

  • TH - TTL High
  • TL - TTL Low
  • WP - Water Pump (tie to ground to enable)
  • G - Ground
  • IN - analog power level
  • 5V - +5 Volts

I am planning to drive TL and leave TH unconnected. I am using a 12 bit D/A to drive the IN signal. I am leaving the WP hardwired to ground for now. Software stops the laser when it detects lid open or the big red button, and I don't have a water flow meter yet.

That gives me four unique signals: +5V, ground, TTL Low, and power level.

Rather than run individual wires to spots all over the Azteeg board, I decided to use the 2nd extruder motor connectors. There are four of them. I am making a daughter board that fits where the stepper driver would be that routes the wires and holds the extra circuitry. I'm using perfboard. I got it about half soldered this morning.

It's kludgey. Maybe I'll come up with something better later.
Bob
"If you didn't code it, it will never own you." (-:
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Re: 2.x for kbob's maker space

Postby mpeele » Mon Jul 28, 2014 4:12 am

We are doing a laser controller also but instead of using a Raspberry Pi we are using a beaglebone and have a front panel which allows for manual control for laser power and laser firing.

TH is connected to a beaglebone GPIO pin for bone control of laser firing.
TL is connected to a front panel push button fire switch which is connected to a toggle switch(open or ground presented to fire switch) to enable manual laser firing
WP is connected to a toggle switch to enable laser power supply.
G is connected to digital ground point
IN is connected to a toggle switch which selects either a beaglebone PWM output or a front panel pot which is connected to 5V
5V is connected to +5V supply.

I think ours is wired very simular to Barts 1.x design which is what we have built.
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Re: 2.x for kbob's maker space

Postby kbob » Mon Jul 28, 2014 4:28 am

Cool!

I saw that in one of Bart's wiring diagrams -- using TH for software actuation and TL for manual firing. Are you using the BeagleBone's PRU processor to drive the GPIO or doing it through the main CPU?

I'm kind of thinking of an iPad as a pendant someday -- if the web interface is good enough, that should be viable. So I'm not thinking about manual control. Touch screens aren't as good as hard buttons, but they're easier to configure.
Bob
"If you didn't code it, it will never own you." (-:
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Re: 2.x for kbob's maker space

Postby mpeele » Mon Jul 28, 2014 5:49 pm

We have a manual interface because its one of the the first things we did just to be able to fire the laser. But we found a manual fire function really made alignment easy and we use it to check and realign. We use the manual laser enable a lot to verify motion without modifying soft configuration. Manual power level setting I use a lot to, it makes it easy to do a cut on paper by turning the power way down and then let the controller control power on the actual material.

The PRU controls all of the realtime I/O during a cut such as motor controls, laser firing, fault detection and laser power level. The ARM processor controls all other I/O such a fans, pumps and nozzle air and provides a data interface between iMac application and PRU.

Currently we have a prototype virtual pendant function in our iMac application which allows for mouse or touch pad controls. This is just a prototype and we are going to do a IOS application based on the prototype pendant. So many projects, so little time. If you just try to replicate a button based pendent on a touch device it can be awkward but if you use the capabilities of a touch device like a iPhone/iPad you can end up with a very nice intuitive interface. Our approach is not to replicate an old implementation with new technology but analyze it to see what can be done with current technology.

With a 100 BaseT network there is not a network issue with either pendant operation or CNC control for our 1.x machine with Nema 17 motors from Bart, 18 toot pulleys and Gecko 351 stepper drivers powered with 24 V and 1.8 amps. It starts to lose steps at about 80 uSec on the heavy axis so we use 100 uSec as the min step timing. Bone will step much faster than our mechanical configuration will support.
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Re: 2.x for kbob's maker space

Postby kbob » Mon Jul 28, 2014 8:00 pm

You say, "we." What project are you working on?
Bob
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Re: 2.x for kbob's maker space

Postby mpeele » Tue Jul 29, 2014 9:50 pm

The "we" is actually 2 people and we are not part of any organization or organized open source project.

We started on a project in 2009 that required a XY motion mechanism and control soft software. That lead us to Bart sometime in early 2010 and resulted in building a 1.x laser as tool and test platform of software. Last year a ShapeOko 2 was added as another test platform and tool for other projects.

So I guess you can say we are working on three projects, a laser cutter, router and control software running on a Beaglebone/iMac and Beaglebone capes. There is also an IOS app in the near future.
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