buildlog.net

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.

I went the exact same route and actually bought from the same seller and I've been very happy (relative to the money spent.). You should check out this thread to see some of the internals better and what other folks are doing with it. I would highly recommend checking the machine for square cuts, I and others have had the X gantry ship "torqued" due to bad installation of the right hand rail bracket.

The software, Moshidraw, that mine came with is a joke. It would not work at all under Windows 7 and would sometimes crash in a way that required a full reinstall of Moshidraw to recover config files to be able to cut. Once I worked out a workflow which didn't trigger these bugs with CorelDraw I got cutting down pretty well, but it would crash like that when exporting as bmp from CorelDraw so I could engrave. I finally pulled the trigger on a 2012 DSP and got it hooked up over the last few days... so far night and day better. I just need to keep tweaking the alignment so it's better.

The other thing you'll quickly realize is that the bed it comes with is worthless as you can't adjust for focus height at all. I want to design a Z lift table that fits in there and I'm looking heavily at the 2.x z table design to do it.

timogiles wrote: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)

Glad to see you are taking the leap - hope you enjoy it as much as the rest of us do.

I also started out with Chinese box. I upgraded it to a new PS, new controller (using Mac3 at first, then moving on to the DSP), etc. Finally, I scrapped the whole thing, built the 2x and moving the DSP to it. Finally, I am happy (but never satisfied - I always want to do something more.) If you count the $ you have already spent, and add what you are going to spend, you will have easily exceeded the $2000 you were hesitant to spend. That does NOT mean you made a poor choice. You can learn so much from the cheapy machine that, when you finally move it to the dump pile and build what you really want, you will have gained a lot of knowledge you you could not otherwise buy for the same amount of money.

Again - welcome. You'll find plenty of help here.

I've got got about $1500 in so far, so Tim is probably right. I'll say that I've learned a lot in the last week, which I'd have had a much harder time with if I didn't start with a functioning machine. I'd probably have spent well over that if I'd tried to build from scratch right off. I have to say K40 + DPS is an incredible value and I could stop now... but of course I won't .

One other thing you need to keep in mind is the exhaust fan it comes with is a joke. It will work for light engraving or cutting paper, but is no where enough air flow to cut acrylic or wood. I got a harbor freight dust collection system and use it for the exhaust fan and now I can cut acrylic with out smelling it.

Tim,

I just ordered the same one on 11-11-11 from ebay seller rumei-shopping, I hope it will be here this week. Glad you got it for $687. I made an offer for $686. I think it was and seller declined, I didn't want to waste anymore time so I went ahead and paid $745. for it. I'm going to be adding the air assist right away also, thanks to Bart for making the drawing available I'm going to make one on my lathe. Just like you also, my plans are to get used to using it a bit then gut it and convert my 4x5 CNC router table to laser.

I'll probably use Mach3 to start with but I think I'll end up getting a DSP from LO, we'll see. I hope to build a 2.x after I get used to all thing laser, maybe a slightly scaled up version.

Anyway, real happy you started your build log ! I'll be following it closely.

Steve

BTW: rumei-shopping's support email is "lovehappyshopping", I guess the same people.

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!

Tim

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.

Nicely done!

I will be the first in line to get that modification. My machine is on the truck for delivery today. Unfortunately, I work from 4 in the afternoon til 4 in the morning and will probably have to wait to get at it until tomorrow morning. All in good time, I guess.

Milt

You guys seem to be following the same path I took back in 2009 before I found a used ULS-25 to rebuild. My original thread was here:

http://www.buildlog.net/forum/viewtopic.php?f=13&t=26