Buildlog Title: WildCircuits Laser HackLog
Member Since: 2010-05-19
Wednesday, February 20th 2013 - 5:39 PM
Sorry to hear that you had a tube blow up.
I run my tube at 16 to 17mA. 18mA is the highest current you can go to safely. I would suggest always using a POT to control your max power. My controller board does the following:
5V PWM output -> POT voltage divider -> laser PSU input
That configuration gives you 100% power when your PWM duty cycle is 100%. If your controller has a malfunction and the PWM is stuck at 100% nothing will get damaged.
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Monday, February 18th 2013 - 5:40 PM
I don't recall if i ever measured what the coil current is that the Moshi driver board applies to the motors. I think that you would be fine with a 1.5A driver, but i don't know anything about Leadshine. Right now on my 2'x4' laser my motor current is 1.1A
I built my own control board based on a PIC microcontroller. I wrote my own program in python to get designs from the PC to the laser, as well as an inkscape extension. I'm planning on doing a detailed writeup about it soon and opensourcing it all, I just haven't gotten around to it yet. A lot of the guys on this forum are using DSPs from FullSpectrum Engineering or LightObject. They sound like they are full featured and do a good job with engraving / cutting, but I don't have any experience with them. I wanted the challenge of doing my own.
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Monday, January 28th 2013 - 10:52 PM
evokanivo wrote:I'm planning a 2'x4' and am worried about a few issues. Would you mind covering in your next post:
-beam divergence: does the spot size or cutting strength vary noticeably based on the XY coordinates?
-do you use a beam expander?
-laser wattage (or better yet, beam width at the tube exit point, if you know it)?
1. the beam does diverge a bit, but it's not extreme and not really a problem. I never tried to measure beam convergence before, so I just went out and had a look at it. I used a piece of scrap plywood and held it on the opening of the focusing head when it was in the home position and the repeated for when it was in the farthest-from-home position. Measuring the two burns that were created, I have: 4.55mm in the home position and 6.65mm in the other position.
2. no beam expanders or any other tricks. Just mirrors
3. my laser is 40watts. I'm using the laser tube and laser powersupply from my DC-KIII. Beam width must be around 4.5mm at the exit of the tube.
I bought this one: http://www.lightobject.com/Pro-laser-he ... -P587.aspx
And I have to say that I love it. It is very well made and adjusting it is very easy. You do have to buy a lens and mirror for it. The lens from my DC-KIII was too small as was the mirror. I also bought them from light object.
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Tuesday, January 22nd 2013 - 12:11 AM
It has been a very long time since I've posted here, but life has calmed down enough that I can get back to my build log. I decided to change direction a little on the electronics and built my own board with the motor drivers built in. Hacking the moshi board like I did worked fine, but the allegro motor driver chips that everyone is using on the pololu boards are so cheap it doesn't even make sense to keep any of the moshi electronics.
I designed up a board using a PIC16F1937 (that's my favorite PIC right now), using an MCP2200 USB to Serial converter and 4 Allegro A4984s. The Pololu boards that everyone is using use the A4988. I chose the A4984 instead because I could get it in a TSSOP package (easier to solder) and the A4988s had a super long lead time. The laser is only using 2 of the motor drivers right now. I put down 4 so that I could use this same board to build a 3D printer in the future. I also have a header on board to get to my E-Stop and limit switches. I bought my boards from iteadstudio.com. I'm very happy with the quality of their 2 sided boards, and they are very low cost. Shipping takes a long time to NY.
I originally bought my DC-KIII with the intention of building a much bigger laser. I wanted a 2' x 4' work area and planned to transition all the electronics, tube, mirrors and power supply to the new laser. That plan ended up panning out quite well. I spent the month of September designing up my dream laser and buying parts. The month of October was consumed with building. By the middle of November I was back up with an operational laser. Here is the computer rendering of my design:
All the aluminum extrusion is from misumi. The total bill was $913 at misumi. I didn't expect it to cost that much, but I did use a lot of it. I decided to build a complete base so that that laser would be free standing, which drove the cost up. I decided to swap out the DC-KIII's focusing optics for a one of the adjustable ones that LightObject.com sells. That allowed me to have a fixed table, which I think is a terrific idea if you are going to build a 2'x4' laser. My linear rails are maker slide that I purchased from inventables. I bought 2 1800mm rails and cut one of them in half to make the y axis. The gantry is just a solid piece of makerslide. When I bought it I wasn't sure it would hold up running the whole 4' of the table ( I thought it might sag) but it has worked out great.
One of the key pieces of my design is that all the custom brackets and connectors were designed to be laser cut on my DC-KIII to build the new bigger laser. This saved a lot of money as several of the parts had to be remade a few times when I changed my mind during the build or something wasn't measured correctly. I remade the gantry mounts several times when I found that acceleration of the gantry was causing the brackets to flex. I had to widen them quite a bit and changed from 3 v wheels to 4 v wheels.
Original gantry mount - only 3 vwheels and not wide enough:
Wider gantry mount and laser head mount:
Trouble Shooting Electronics:
Everything is finised enough to get back to production!
I decided to skip the expense of Alupanel and skin the laser with luan plywood. I bought to alumium foil to cover the insides of the wood panels with in case of a beam alignment problem. I don't really want the sides to start on fire. I haven't actually installed my safety aluminum foil yet though.
I'll save the rest of the info of my build for another post.
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Friday, January 20th 2012 - 2:56 AM
I haven't posted any updates in a while, so I've got a back log of things to talk about. Here is my rotational adapter:
My brother likes to homebrew his own beer so I thought that it would be a great Christmas present to give him a set of custom engraved bottles. Unfortunately that meant that I couldn't post about my progress in case he was reading. The bottles came out awesome and he really liked his Christmas present! My wife helped design 5 custom altered logos. She has serious photoshop skills. We took 5 of his favorite brands and incorporated the words "Homebrew" and his name, the 6th label was a totally custom design. The bottle in the picture has a modified Stone Brewing logo on it.
The rotational adapter cost only a few dollars to make. I harvested the stepper motor, drive belt, pulleys and 2 shafts from an old photo printer. The two wood side plates I designed up to the correct dimensions to fit my printer hardware and cut out with the laser cutter. The two wood sides are held together with 3 pieces of 1/4-20 threaded rod and a few nuts and bolts. The whole process of part scavenging/designing/fabricating took a whole Saturday including a trip to Lowes for the threaded rod. Not bad for a day's work. I have to say that it is incredibly rewarding to design something and be able to make the parts myself and by the end of the day have a working mechanism.
I got lucky with this stepper motor. It is a bipolar motor and was compatible with the moshi driver board that I'm using on my machine. I've replaced the brains of my moshi control board with a PIC running my own code. If I didn't have discrete control of the motor driver this wouldn't have worked. I unplugged the Y axis motor and plugged in the rotational adapter motor. The problem with the moshi controller is that on power up it finds home. the Y axis doesn't find home when the motor is unplugged
. Another quirk is that DPI of the rotational adapter ends up being 3000 with the standard gearing that was in the laser printer. That is easily fixed, all my Y moves are multiplied by 3 when I'm using the rotational adapter. Lastly, the plug that was on the stepper motor cable was the correct size to fit into the moshi board, but the windings were not pinned out correctly. I think it was wired A-B-/A-/B but needed to be A-/A-B-/B.
I have lots to say about my PIC moshi controller, I'll have to save it for another post.
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Wednesday, November 30th 2011 - 4:59 AM
One of the things I mentioned in my last post was reverse engineering the USB communications of the Moshi board in the DC-KIII. I used SniffUSB to monitor what traffic there is between the computer and the laser. It went surprisingly well on the data collection and data parsing end. The instructions I linked to were a big help. And that is about the point where I could go no further.
I had the laser setup to a 1" square that I drew 1" from the X and Y home position. I figured that knowing the measurements of my drawing and changing 1 thing at a time I ought to be able to piece together what was being said. I started by cutting out the same drawing at 3 different speeds. I compared the data transferred to the machine but couldn't quite make sense of it. I repeated a few times and my data didn't get any better.
I was googling to see if anyone had done anything similar and I found someone talking about the parallel port model of the DC-KIII. It uses a parallel port version of the Moshi board that is in my laser. He mentioned that the communications to the board over the parallel port were encrypted. This is something I had not considered, so maybe the USB communications were encrypted too? I went back and cut out my 1" square again, capturing the communications. This time I cut out the same shape 3 times without changing anything. Looking through the captured data you can see that each time the computer talks to the laser, it says something completely different (same number of bytes though). Long story short, the USB communication to the laser seems to be encrypted and I don't have the skills or patients to try and reverse engineer that.
So I gave up on taking control of the Moshi board without modifying it. On to Phase 2...
This controller itself is pretty well designed, it's real down fall is that it only works with the MoshiDraw program. In the picture above is my component breakdown of the board. I spent a bit of time going through the datasheets of the parts that I could identify and traced all of the signals back to pins on the 40 pin unlabeled processor. It's quite convenient that they used a DIP package for that processor, because my new plan became removing the processor and controlling the stepper drivers with a PIC. The best part is that it's completely reversible by just pulling off my PIC and replacing the moshi processor chip.
The stepper drivers are TEA3718. There are four of them, each one controls one of the phases of the 2 motors. The drivers have 4 levels of current that you can drive through a phase. [None, Low, Med, High] If you drive the DC-KIII motors in full step mode then you end up with 250 steps/inch, so the Moshi board drives the motors by quarter stepping. From the 40 pin socket you directly drive all of the phase/in0/in1 signals through a 74HC273 octal D flip flop to get to the TEA3718. Essentially, you setup your phase/in1/in0 signals and then use the clock signal to load it to either the X or Y motor.
The 40 pin processor is intended to communicate with the unlabeled USB chip on the Moshi board. Unfortunately the communication between the 2 chips is on pins 2 to 9 of the processor. If you look at my diagram you will notice that these are the pins used for phase/in1/in0. Between the processor and the usb chip is a 74HC245. Holding pin 13 on the processor socket high will keep the USB chip from being able to control the phase/in1/in0 while you are driving the motors.
Ultimately I'm going to make a small PCB that will plug into the 40 pin socket. It will have a USB-UART connection (Microchip MCP2200), an 8 bit PIC micro (PIC16F1936), an SRAM (probably a 23K256). A few years ago a built a CNC pcb router and designed and built the controller myself. It has a simple serial interface and I'm doing the same thing with this PIC. I'm using my PCB toolpath script and feeding the output across the USB-Serial connection to the PIC. In the picture below I've soldered wires onto the backside of the Moshi board corresponding to the important pins that I identified. I have a PIC16F1936 on a little breakout board that I made (and use for just about everything). That is my test bed.
Tonight I finished my motor driving algorithm, you can see the results below. I hope to be able to put something together and sell for low cost that will be a plug in for the Moshi board. I think it could be a hit with the crowd of people who don't want to drop $500 on a DSP but want more than Moshi Draw can offer. I still have quite a few things that need to be tested. I want to add PWM power control, add an SRAM (part number noted above) so that a job can be loaded and cut more quickly, etc.
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Tuesday, November 22nd 2011 - 12:57 AM
twehr - It's cool to hear (or read) that you started out the same way. I've read about a million of your posts here, but I didn't know you started with one of these machines.
Gadroc - Thanks for the link. I've searched and searched but I never came across that thread. My Googling skills have failed me. I agree that MoshiDraw is a little lacking but I've had pretty good luck with it so far. I'm converting everything to 1000dpi monochrome bitmaps and importing to MoshiDraw. That has been working out pretty well.
I think before I breakdown and buy a DSP I'm going to look into reverse engineering the USB protocol for the Moshi card and see if I can make my own driver and interface it to a better program. If anyone has done anything like that before and would like to collaborate, chime in. I've found a little bit of information that makes me think that I can hack it. http://ieee.students.mtu.edu/node/47
I made a bit of progress this weekend. Right now the laser is living in my garage. I used some of the nice thick foam that the laser was packaged in to build a window insert for my exhaust tube.
I have a bunch of luan plywood scraps left over from a kitchen remodel. I played around and cut out and engraved a few things from that. I can safely say now that the exhaust fan that came with the laser is a little on the wussy side. i also have a 1970's range hood that was removed from my kitchen which may get grafted into my exhaust setup... we'll see.
Let's talk about the table on this machine. I'm not sure why it is designed the way it is. The laser can easily be used over a 11"x7" range but the table is designed to hold something much smaller. I want to get some of that aluminum eggcrate material that others have been talking about lately, but I don't think that I can get a local source, so it'll be a little while. In the mean time I decided to make a wood table with manual height adjusters. As much as I can I'm making the parts that I need on the DC-KIII. That saves time, money and make me feel inginuitive.
Here's a shot of the machine with the standard table. This is a picture that I took right when I got the machine; the red thing is a ribbon that the machine shipped with the hold the laser head during shipment.
I removed that table and the hex standoffs that held the table up. I drilled out the holes that the standoffs used to fit 1/4-20 threaded rod. I used a locking nut on the bottom and regular nut on the inside.
For table height adjustment I'm using a standard 1/4-20 nut, one on each of the 4 threaded rods. To adjust the height with the table on I designed a 3 piece topper for the nut. the bottom piece is 1" diameter and has the hex shape of the nut cut in the center. On top of that sits a 1" diameter piece with the center hole the diameter of the 1/4" rod. The top piece is 3/4" diameter with a hole in the center for the threaded rod and two holes on the sides for my adjustment tool.
Lastly I cut a piece of luan to use as a temporary table. I used my step drill to make the hole for my adjusters. as you can see in the pictures I went one step to far on all of them. oops. I then adjusted the table up into the laser's focus and cut out a grid, just like the eggcrate that I'll get someday.
More updates to come. I'm having a great time with this laser cutter and I'm excited at all the making possibilities!
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Friday, November 18th 2011 - 6:20 AM
Like many others here I have been lurking for a long time, silently plotting how to end up with my very own laser. I've been playing with a 1watt 808nm diode for a while. It's fun to play with but it isn't very effective on many materials. 40 watts of CO2 seems to be the way to go, but it looks like most people are spending around $2000 on their 2.x builds. I decided to purchase one of the cheap DC-KIII lasers of ebay and use it as a starting point. I've had it for a couple of days now and I'm pretty impressed so far. I'm calling this a "HackLog" because I will be Hacking/Modding/Upgrading this laser until it is basically a 2.x variant. I ultimately want a 2' x 4' cutting area. The DC-KIII has two selling points for me: (1) it contains most of the laser bits I'll need to put together a larger machine, (2) the instant gratification of making smoke after one evening of ownership! (it was only good smoke, just to be clear)
Since I've read good things about Love-happy-shopping here I bought from them (the actual seller is qiandingzhensatisfaction, but they are the same). Some of the their listings state the location being in california and having free shipping. I really wanted to avoid shipping an entire laser cutter from china as there are lots of stories about extra charges and difficulty with customs and shipping. In mid october prices dropped to $687 for a couple of days and then went back up to $750. Over the summer prices were around $840. I wasn't paying attention (and wasn't ready to buy) during the price low in October, so I put in an offer for $687 on Nov 7th. On Tuesday I had large pacakge on my porch
I have to say that I'm really impressed with the packaging that these guys did. They sent it in 2 packages. A smaller package contained the exhaust fan, water pump, exhaust hose, software cd, power cord and usb cord. I found that one of the screws had backed out of the fan during shipping so I had to open it up and screw it down. That's only quality issued i've encountered.
The laser was in a larger package. The laser was wrapped in about 8 layers of bubble wrap and taped. That was inside a cardboard box that was completely surrounded with 3/4" foam that was inside a cardboard box hermetically sealed with packaging tape.
So I've played with it a little so far and I'm pleased to say it works. I've got the day off tomorrow and I'll be working on getting the exhaust to go out my garage window and fabricating some sort of air assist.
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