Watt’s up, Doc?

February 24, 2013

power_test 3

So finally after about a year on the back burner, I finally managed to get some time in on the LASER. I have been slowly acquiring bits for the re-build over the past year, but this is the first real hands on moment I had for a while. One of my more recent acquisitions for the LASER was a 100W power sensor for measuring the output power of the LASER. The idea being that I would use it to monitor the health of the tube and my optical path once I got everything up and running. I also wanted to have an idea of what the real power was of my “free” LASER that had been sitting around for about 3 years before I got my hands on it, and then another year now on my shelf. So while the LASER was relatively new before being relegated to the scrap heap, a lot has happened that could have resulted in a drop in performance of the LASER. I’ve herd stories of the glass tube LASERs dropping in power output, even if just sitting on the shelf for a while‚Ķ So I’ve been wondering if the same is happening to my LASER.

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Back on the air

May 14, 2012

Sorry for all the static folks. Personal and financial setbacks have forced me to put the project on hold for a while. Rest assured it is not dead, just delayed, and will be getting back up and running in the near future, with perhaps a slight shift in direction, but we’ll see when we get there ūüôā [I know I said this before, but this time I mean it… I promise!]

Also, while I initially planned on having this blog for the laser rebuild project only, I’ve decided to expand my content and include some of the other projects I’m working on¬†[or rather planning to], or dreaming up ūüôā I will mostly keep the projects centric around making, or tools for making (like the laser), to keep a general theme for the blog. This will help keep some form of content flowing for the few of you that are following along, and allow me to document some more of the things that interest me.

Stay tuned, more to come!


In the meantime

February 8, 2012

Here is another LASER re-build I’m somewhat involved with.


It’s a *slightly* larger scale than the one I personally have. ūüėČ


The Living Dead

February 3, 2012

Okay it’s been quite a while since I last posted. The project has come to a bit of a standstill, only due to a lack of time, and budget. The holidays were busier than I had expected, and I had a car accident between Christmas and New Years which ate into my budget for buying parts. So while things are on hold for the moment, the project is far from dead. I’m still working on various solutions for some aspects, and will be posting again soon. I also expect¬† the actual re-build process to start in the near future. So please hang in there, the ride is about to start.



December 28, 2011

For those of you that have been following along, you will remember that the X rail for my old ULS-M25 is badly warped from the fire. To replace it with an official part from ULS will cost me $365 + taxes [or about $13.50/inch for the 27 inch extrusion]. Needless to say, this is a unpalatable price for an aluminum extrusion. So I’ve been trying to come up with possible replacement solutions that are more cost effective. The first step was to create a CAD model for the existing part to serve as a reference. While my model isn’t exact, as it is based on measurements of the damaged part, it should be close enough to serve its purpose.

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The wiring harness

December 10, 2011

Today I took on the relatively arduous task of mapping out the wiring harness as it will need to be totally replaced. Fairly large portions of it are severely burnt/melted, more than I had initially noticed/assessed. For the most part it it is fairly straight-forward point-to-point connections. I started with the door sensor loop, as it is the most damaged.

Door Sensors & Bypass Circuit:

CTL[13] --- + --- <RSL> --- <LSL> --- + --- <RSD> --- <LSD> --- CTL[9]
             \                       /
              \ --- --<     >-- --- /
                 Lid Sensor Bypass
RSL/LSL: Right & Left Side Lid sensors
RSD/LSD: Right & Left Side Door sensors

As you can see the magnetic door sensors are simply connected in a loop. There was a mystery connector on the top of the chassis, as it turns out this is used to form a bridge across the lid-door sensors, effectively bypassing them to allow operation with the door open. Unfortunately I had to destroy this connector to remove it, so I will need to find a suitable replacement. [I didn’t have the bridging plug anyway]

Next up is the connections to the front panel. I had initially assumed the mystery RC on the control board was for debouncing an input from the wiring harness, but as it turns out it is a straight connection from the main controller to the front panel. So the purpose of the RC remains a mystery for the time being. The connection is a standard IDC ribbon cable [26 pins].

Another unknown [but assumed to be for the rotary attachment] was a completely melted DB9 connector. Once I unbundeled the harness, I was able to confirm that it indeed was for the rotary attachment, as one set of wires went to the stepper driver, and the other to the main controller.¬† I was able to determine a pin-mapping, but don’t know the function of each line yet. Although the insulation was burnt off, and the connector was melted beyond use, the bare copper of the wire remained, and all the wires appear to have remained in their relative positions.

Rotary Attachment Connector:

1 - Stepper   6 - Stepper
2 - Stepper   7 - Stepper
3 - N/C       8 - N/C
4 - Homing    9 - Homing
5 - Homing

Next I Mapped out the Stepper driver connector, which is a 20pin ATX power connector style connector. The connections are as follows.

 1 - Rotary[6]           11 - Rotary[7]
 2 - Rotary[2]           12 - X[5]
 3 - Rotary[1]           13 - X[6]
 4 - Shield [Rotary]     14 - X[7]
 5 - Shield [X]          15 - X[8]
 6 - Shield [Y]          16 - Y[3]
 7 - Shield [Z]          17 - Y[4]
 8 - Z[1]                18 - Y[2]
 9 - Z[6]                19 - Y[1]
10 - Z[8]                20 - Z[3]

I will need to analyze the stepper driver board to try and determine the wire parings for the motors. Though I may also be able to derive it from the stepper datasheets I can find. Though given the pinout, I am imagining its:

Axis   PhaseA  PhaseB
Rotary  1&2     6&7
X       5&6     7&8
Y       1&2     3&4
Z       1&6     3&8

I’ve confirmed the Z pairing via the datasheet. The motor side has jumpers between 2&6, and 5&7 placing the coils in series for bipolar operation.

The remaining wires all run to the same 34 pin connector [J4] on the main controller board. This connector contains the LASER control, safety loops, and homing & limit circuits.

 1 - CO2 Modulation     2 - Opto Return (Modulation & Diode)
 3 - LASER Diode        4 - N/C
 5 - AIR[5]             6 - AIR[6]
 7 - AIR[2]             8 - BEEP[1]
 9 - DoorLoop          10 - BEEP[2]
11 - INT[6]            12 - LASER Interlock Out
13 - DoorLoop          14 - INT[5]
15 - N/C               16 - N/C
17 - AIR[8]            18 - VCC (XY[3])
19 - GND (XY[4])       20 - LIM[2]
21 - GND (ZLIM[4])     22 - N/C
23 - XHOME (XY[1])     24 - N/C
25 - YHOME(XY[2])      26 - GND (ZLIM[2])
27 - LIM[3]            28 - LIM[1]
29 - Z-LIMIT (ZLIM[1]) 30 - VCC (ZLIM[3])
31 - Rotary[4]         32 - Rotary[9]
33 - Rotary[5]         34 - N/C

I forgot to map out the Z axis limits board (ZLIM) so I’ll need to do that to determine their final functions. [I’ll come back and edit this post once I get a chance to do so]

There’s a trio of unknown connectors I’ve labelled as AIR/INT/LIM; I’m assuming these are for the Air-Assist option. The connectors were present on my harness, but not attached to anything else, with the exception of the INT connector which had a small loopback plugged into it for two of the wires [5&6]. INT and LIM are bundled together, and were located in the back right corner of the unit inside the engraving chamber. AIR and a 48V power connector were located on the bottom of the unit below the laser & electronics [outside the engraving chamber].

The INT/AIR connectors also have a set of wires that runs between them as follows:

 1     7
 2     1
 3     4
 4     3

Based on the pattern within the main connector, I’m guessing that INT 5&6 form some sort of safety/interlock loop like the door sensors do. [hence the reason they are looped together]. The LIM connections appear to be another set of limit/homing sensors. So perhaps this is not for the air-assist option as previously thought, as I cannot think of why we would need en extra safety-loop and limit detector for air-assist. Though if it’s not for air-assist, I have no idea what it could be for.

The final connector, is the one on the back of the LASER itself. The pinout for it was pulled from a ULS OEM LASER manual.
LASER Pinout:

1 - +48V    4 - N/C           7 - GND       10 - N/C
2 -  N/C    5 - Interlock In  8 - +12VOut   11 - LASER Diode
3 -  N/C    6 - Modulation    9 - RET       12 - N/C

Note that the pinout does define additional signals, but I’ve only included the ones connected in my harness here.

Actually there a re a few more connectors, but they are for power, which is straight forward. And the two break-outs for the back panel connectors to the mainboard, which are of no consequence here.

[Update]Added the Z-limit signal assignments. The board is arranged differently than I had imagined. I had assumed the two LED’s would have been in parallel, and each limit would have had a discreet output, given the 4 pin connector.¬† But the board is actually arranged such that the two LED’s are in series, as are the two photo transistors. In this arrangement if beam is broken at either detector the sense loop goes open circuit. The only downside to this arrangement is that you have no idea which side was broken, but one can extrapolate that from the direction of motion. [assuming everything is set up correctly][/update]


X motor PCB’s

December 6, 2011

Almost forgot, there is a pair of small PCB’s that need to be mapped‚Ķ The PCB that sits over the X stepper motor, and the one that connects the flex cable to the main wiring harness. For all intents and purposes these two PCB’s can be thought of as a single PCB, and that’s how I’m going to handle them [it looks like ULS looks at them like this as well, based on their component designators]. The main wiring harness plugs into the lower PCB which is bolted to the chassis. This PCB simply passes the signals onto a flex cable, that runs the signals up to the upper PCB, which then breaks them out for the X stepper motor, and the X & Y homing sensors. With the exception of a handful of capacitors, and a couple of resistors, there really isn’t anything to the PCB’s.

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Second Sourcing: Belts

December 6, 2011

So now that I have my quote in from the ULS rep for my list of parts, I thought I’d go through the list and see how much of it I can second source from other suppliers outside of the ULS umbrella. So for starters I decided to go with what is most-likely the easiest part to find elsewhere‚Ķ the timing belts. Now I don’t know much about timing belts, but figured they were an off the shelf component. So after doing a little research online, I discovered that the pitch/profile for the belt is known as MXL (Miniature Extra Light). I wasn’t sure on the material of the belt, but I did come across a spec that stated it was kevlar re-enforced. After searching he usual retail suspects [McMaster Carr & SDP/SI as well as few others] it became apparent that the material must be urethane. So armed with that information, as well as the length¬† and width specifications for the replacement belts, I came up with some pricing:

The base spec for all the belts is: MXL (0.080) pitch timing belt x 1/4in wide, urethane belt with kevlar re-enforcing members. All are closed loop belts, for open they will be cut. (McMaster & SDP-SI don’t have kevlar re-enforced belts that are open)

Short Z belt: [meas: 105 teeth closed] (there is some flex in the length due to the adjustment mechanism, s0 103-108 should all be ok)
Primary: 105MXL, 105 teeth [8.4in] SDP/SI – A 6B16-105025 [3.52]
Alternate: 103MXL, 103 teeth [8.2in] McMaster – 1679K93 [2.55]

X Belt: [spec: 5.25ft / 63; meas: ~60in – open]
Primary: 962MXL,  [77in] McMaster Р1679K686 [9.61]
Alternate: 1500MXL,  [120in] SDP/SI РA 6B16-15C025 [21.33]

Y Belt: x2 [Spec 3.25ft / 39in; meas: ~37in – open]
Primary: 482MXL,  [38.5in] SDP/SI РA 6B16-482025 [5.54]
Alternate: 482MXL,  [38.5in]  McMaster Р1679K683 [5.84]

Now I could probably do even better here, but for 1 off, there is no real need to. At $24.21 for all the belts, I’m roughly 1/6th the quoted cost of $140! That’s $120 savings right there‚Ķ if I can keep this up, I just might be able to swallow the outrageous price of the extrusion.

[yes I know the prices above are US dollars, and the quote was in Canadian, but given the value of the dollar right now, I consider them to be pretty much equal]


The front panel (part 2)

December 2, 2011

Today I took on the front-panel control/display board. The board is pretty much charred as you can see. It has quite a few traces on it, but is fairly simple in function, thus making it relatively easy to decode.

Before even doing any cleaning I tried  to make some pretty good guesses as to the architecture, the next paragraph is my assessment from before I started.

There are 2 IC’s on it, which are likely some sort of tri-stating buffer, allowing the switch signals to be multiplexed onto a data bus. The data bus also feeds to the LCD.¬† Then there are the 2 LED’s, these are fairly large and probably consume a bit of current, which would explain the two transistors beneath them, likely acting as low side switches. There’s a 3rd transistor on the board, which I’m not sure of the function yet, but it should become more obvious as I trace it out.

Now lets get into it and see how well my guess did.
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The front panel (part 1)

December 1, 2011

Today I took a bit of time after work to map out the membrane keypad of the control panel. Unfortunately it was badly burnt up, so unusable, and I didn’t take the best of care pulling it off.

However, fortunately enough, it mostly came off in large pieces, so I was able to put the pieces together enough to trace out the signal mapping. to make life a little easier, I took a picture from the backside where the traces can be seen, and then traced out the lines in CorelDraw. Virtually any membrane keypad can be reverse engineered this way, as they are almost always printed on transparent material. Read the rest of this entry »