Laser Engraver for Duck Calls

[BearKraft]

I am in desperate need of some help on building a simplified CNC Laser Engraver. I owned a CNC Router for a little over a year and ran it with Mach3. Got pretty comfortable with the setup and use of the router, but I didn't personally do any of the programming on it. All the parameters were setup for the machine when I got it. I need a Laser engraver big enough to engrave 2 dimensional pictures and text on Duck Calls (max 6" long 2" diameter with 5/8-7/8" inside bore). I am thinking of trying to build one myself out of an old printer, but do not have the electrical expertise to know how to setup the wiring or the parameters for the CNC portion of it. I do have a 4-axis stepper motor controller, but I will only need to use 2 maybe 3 axis for this. The other problem I have is the laser. I am laser stupid! I only need to burn maybe 1/16" or less into wood or acrylic, pretty much just making a mark, but I have no idea what wattage laser I need to do this. I am also not sure on what I need to control the laser. I assume that there is not an inexpensive switching device that turns it off and on in correspondence with the MACH3 program? (that would be too easy) Am i going to be able to run Mach3, or will I need another program?

Any help here would be appreciated. And I know there will be a lot of people who have opinions on what I should do, but I will be up front about it. I don't have $10k to spend on a Versalaser with Rotary attachment. There has to be some way to redneck engineer something for this application! I would also entertain any proposals for someone who has built their own homebuilt laser to build me one if they are willing. Feel free to avoid the criticism and PM me if you want.

Thanks in advance,
Bear
www.bearkraft.com

[zax15uk]

Hey Bear, well a modified printer is certainly an option. Since you need rotary engraving the rollers could be made to turn the tube while the head scans the length.

Yes, Mach3 should work ok. You probably need the laser (raster) plug-in which is available on their site. The problem would be the laser, your application won't need much power - so a small (25-40W) CO2 would work great or you could try with a high wattage diode laser (the driver PSU is always the problem here).

Cost wise, I would look at the laser and other components and see if it makes sense to build your own or buy a Chinese model or even a used brand name.

If the diameter varies, you may also need a Z-axis to control focus. I am sure Mach3 could handle this but haven't tried.

Zax.

[BearKraft]

Zax,
Thanks for the input. As far as the Chinese models, I would probably go that route except I haven't been able to find one with a rotary attachment until you get into $3000+ range. On the Diode laser, how much is considered high power? I've seen them up to 1W on Ebay, but compared to a 10W CO2, I just don't think it will do much. Also PSU? Pulse Sending Unit??? Just a guess. Is this just the problem with the Diode laser, or is this also something that you need for a CO2. I have been unable to find any information on adapting CO2 lasers to homebuilt machines. Other than the tube and a power supply,what do you have to have to run one? What do you use to transfer the laser from the tube to the engraving head? I think the Diodes use fiber optics?, but didn't see any info on how the CO2's work.

I apologize for being so uneducated on this, but I like to figure out ways of doing things that are cheaper than purchasing a ready made unit, especially when I would have to purchase a monster unit (just to get the rotary attachment) to work on my very small items. Just so happens that this project includes very few skills and technologies that I'm familiar with. I promise, I'm a quick learner and hopefully the elementary questions will stop soon!

How much programming is involved to get the Mach3 program to run the old printer stepper motors? I'm sure its pretty simple once you have the info from the motor, but I don't know where to start in the Mach3 program to enter the specifics.

Thanks again,
Bear

[zax15uk]

You are in the ball park at $3k for a Chinese laser w/rotary, and anything less than that is probably not what you want anyway.

No - you'd need more than 1W, probably a 25W diode laser would work. The PSU (power supply unit - see, much less complex than the pulse sending unit) needs to be able to quickly switch several amps of current while keeping a stable voltage and eliminating any spikes. It isn't something you're going to build. Yes, they can use fiber optics, or direct to a lens.

The CO2 laser on the other hand is pretty simple, you can get away with a neon sign supply (slightly dangerous, but then so is the laser) for a PSU, but a 'real' supply isn't that expensive and is likely to have features for faster on/off switching (tickle voltage to keep it 'ready'), variable power control and will make the tube last longer so pay back in the end. Obviously this is the route to take.

You can buy mirrors and optics from ebay or from China, although you'll need to make sure to get the correct components (when I have time I'd be happy to provide some links).

The printer conversion is dependent on what motors it has, probably some very small steppers. If it has 6 or 8 wires you will not have any trouble hooking it do your driver, just make sure you keep the current low and see how much heat is generated. Mach3 only needs to know how many steps/inch etc, this can be figured out later.

No problem regarding the questions, keep 'em coming... although I may be slow to respond the next couple of days as I'm travelling back to the US (after a month in Asia on business).

Zax.

[BearKraft]

I see that the higher power diode lasers and power supplies are going to cost as much if not more than a comparable CO2 tube. What else do you need to run the CO2 laser?

Here is a link to the 4-axis cnc driver I have:
http://cgi.ebay.com/4-Axis-CNC-Laser...item518d2e1154
Will this interface with the diode laser driver to tell it when to switch on or off, or how does that work by running Mach3?

Same question on the CO2 laser, how does it get the info out of Mach3?

Links would be helpful. I would like to get an idea of how much I will have to spend before I jump into this!

If it looks to be too expensive, I may look at doing a rotary type cnc with the parts i already have.

Thank you for the patience and information,
Bear

[zax15uk]

Bear, yes that is true. A suitable diode laser with power supply and optics will cost at least as much and probably slightly more compared to a CO2 system (if you are looking at a Chinese glass tube). The difference is the diode will last 10,000-20,000 hours and the Chinese CO2 tube perhaps 2,000 hours.

For the CO2 laser you're going to need to mount the tube at the rear or side of the machine, it needs to be static as they are fragile and require water cooling. Then you'll use 2 or 3 mirrors (generally gold flashed onto silicon, front surface) and finally a lens (ZnSe is typical) to focus the beam. I am not a lightobjects fan but since you bought the driver board from them you may want to check out their site as it has all the components. It will give you an idea of prices, although everything would be cheaper to import yourself.

Laser tube 250
Laser PSU 200
Mirrors + Lens 100
Hardware... ?
Water pump, air compressor (not necessary but a good idea)... ?

The driver board would interface to the printer steppers (depending what type it uses) and you would take one of the remaining pin outputs to a DigiSpeed (0-5v output) and input that to the laser PSU. It is also possible to connect it directly if you have an opto isolated breakout board. Most of the laser PSU's have either PWM (pulse wave modulation - meaning it accepts pulses from the PC just like the driver card does) or voltage scaled inputs like the DigiSpeed creates (again, from the PC pulses). No other interface is required, so it is basically bypassing your driver card and hooking to the PC parallel port directly (wth buffering since the laser PSU is very high voltage).

I use both CNC router and laser, in this application the laser would win. You just need the right lens and it will be much easier - no curvature to worry about or depth control issues that the CNC has.

Zax. (off to the airport)

[BearKraft]

Zax,
I think I have figured out that I am not ready to jump into the Laser part of it yet. Seeing as how this is going to be my first machine build on my own, I don't want to sink a bunch of money into it just in case it fails. I do already have the items I need to build a rotary engraver so I am thinking about trying to rig that up as a 4 axis. Maybe upgrade to the laser later. So, as far as the curvature and depth control, how can you take care of that with the router? I have DeskCNC and Enroute, are either one of these capable of creating 4 axis G-code? If not, what is a relatively inexpensive or free program to achieve this with? Most of the duck calls will have a tapered barrel, so I thought about just jacking up one side of the rotary axis and running the program as flat, but that will still cause problems even though the engraver tip will be at the same level, the revolution will be quicker on the smaller end.

I did get one of the motors running last night. Got hot pretty quick though, luckily I won't be doing any large projects with them. I am sure I will need help with motor tuning once I get everything built, but I am going to work with the Mach3 literature and give it a shot on my own first. Maybe this way I will know what questions to ask!

Hope your flight went well,
Ben

[zax15uk]

You probably need to reduce the current if it's getting hot, if the driver has a setting to reduce the holding current you might want to enable that too.

I wouldn't try to use software for the curvature (taper), instead go with a floating Z-head. This will ensure you get a constant depth. Depending on your spindle it may not be too hard to implement.

The cutter is spring loaded and has a 'foot' that rides on the material so the cutting depth remains the same.

Zax.

P.S. I made it home, so I guess the flights were good enough

[BearKraft]

I can't find any adjustments on the controller board. I am running a Condor 24V 1A power supply. The controller calls for 12-36V. I also tried my battery charger which is 12V 2A, but the motors still got hot. I tried a 6V cell phone charger, but it was just enough power to get the motor to flutter. Not sure what the printer was running for a power supply, but I'm going to look at that tonight. Maybe 9V is the trick??? Maybe I'll just run em til they melt!

I also figured out that the new printers and dvd burners are using 2 wire motors which look to be small servos instead of steppers.

I was able to turn a 5-wire stepper motor into a 4-wire last night and am able to run it with bipolar controller. I read something somewhere that it was impossible to use a 5-wire with a bipolar controller, but the redneck and a dremel was able to figure it out.....

Working on the rotary axis tonight, hopefully more progress to be made! I understand the floating head idea, but can't find any pictures of any "rigged" up models to get ideas from. Guess that will have to be added later. Maybe I'll go with a very slight taper on my calls for now.

Glad you made it back ok.

[zax15uk]

The driver board should have some adjustment pots to change the output current limit, the input voltage will have some impact but it's the output current that needs to be adjusted. 5-wire is probably just a common ground configuration so should be capable of bi-polar operation.

If you search for 'router floating z head' you'll probably find some pictures, there's been several discussions on them before and are fairly common in the sign inductry for engraving brass etc where the thickness isn't well controlled but you need the depth of letter to be constant.

Try here: Floating head on Kress router

Zax.

[BearKraft]

Did not see any adjustment pots, but after messing with it last night, I think I may have screwed up the board. I got the x and z-axis built and wired, so I was going to try it out. Jogged the x axis back and forth for about 10sec and it worked fine. Moved the z about 2mm and the power led starts flashing. I see it's only getting 4-8V so I think its the ps. I disconnect from controller and it's putting out 24V. Hook it back up, it's flashing and giving 4-8V again. I thought if I fried the board it would just be dead, but I can't figure this one out...

Bear

[zax15uk]

The motor may have shorted internally causing an over load.

Many power supplies will 'shutdown' from over current.

You could try hooking the other axis motor to it and checking it out.

I looked at that driver board, and don't see any way to limit the output current - perhaps it is supposed to have limit resistors installed but without knowing more about the design it is hard to say.

Zax.