Laser – J Tech Photonics Tips and hints

New Home Forum Mostly Printed CNC – MPCNC Your Builds – MPCNC Laser – J Tech Photonics Tips and hints

This topic contains 93 replies, has 12 voices, and was last updated by  Zeenon 2 years, 6 months ago.

Viewing 30 posts - 31 through 60 (of 94 total)
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  • #5504

    karltinsly
    Participant

    Hey thanks for the callout. The new one looks much better, and the clearance for the slide looks good.

    Karl

    #5505

    Curt
    Participant

    Here is an updated version of my mount. I also modified Karl’s mount to remove the laser holders since I like his better!!. http://www.thingiverse.com/thing:1250531

    #5509

    karltinsly
    Participant

    Thanks, Curt!. My version of the laser mount has enlarged holders for the line lasers, but since you didn’t need those, the credit for the parts you kept should go to DuctSoup, who did the original design I used: http://www.thingiverse.com/thing:1025450.

    #5511

    karltinsly
    Participant

    I will. I’m thinking about some different designs. I’d like to incorporate all the control functions – LCD, laser driver, router speed control (I’m using the harbor freight one) – into one panel, if possible, with RJ45 connectors for the low power connections and some molex connectors for the high power ones (laser, extruder heater).

    Here’s a question: to change the power output on the laser driver, you need to change some jumpers. I would like to be able to change the power easily with some toggle switches, or maybe a rotary switch. Anyone have any ideas for this? 4 toggle switches would give access to the 5 power levels (with the lowest power, .5w, being the default if all switches are off).

    EDIT: It would actually take 5 switches, since there is no connection for the lowest level.

    #5522

    Curt
    Participant

    Along with the jumpers you need to adjust the pot to get the right voltage and they is set with the laser disconnected. I guess I do not see why you would need this. If you set up the laser at the max (recomended) setting then use the M106 Sxxx to adjust power with S255 being max power and S0 being off.

    #5524

    karltinsly
    Participant

    Thanks, Curt. So what you’re saying is that for my 2.8w laser, I should set the board to 2.5w output, turn the pot down and focus the laser for whatever my focal length will be, then turn the pot up, and just let the M106 command control the output over its full range from that point on. I shouldn’t have to change the jumpers or mess with the pot again unless I change focal length, right?

    Makes sense to me. Does anyone know of a reason not to do it this way?

    #5525

    alan
    Participant

    That’s how I did it. Working so far, though I have to always fiddle because I change material size and Z height, which is why I think we all need a good spacer block that sets the Z exactly where we want it every time.

    Sometimes I use a really low S number to test my focus and adjust Z height if necessary.

    #5526

    Curt
    Participant

    Yes, the jumpers and pot should not be adjusted unless something physical changes. Per the J Tech website they recommend that the laser be set up at a little over 2W to preserve the life of the diode. In the PicLaser and Laser Etch software the laser power is changed automagically via M106S.

    #5631

    Leo69
    Participant

    I like the Jtech gear and their website but I think it’s worth mentioning that there are much cheaper solutions available for laser add-ons. In the true “Most bang for least buck” spirit of the MPCNC you should consider building a laser add-on yourself. The Jtech laser is $350 and is a kit with 2.8w laser and the driver. After that you need the $20 fan upgrade and the $40 software package so it’s a $400 project which rivals the cost of the entire MPCNC build. Take a look at DTR laser shop and you’ll find the same 2.8w 9mm 445nm diodes mounted in a module with a 3-element lens for $70. Add another $20 for a heatsink and driver board and you’re in business. Free software options exist as well so you can do the whole thing for about $100.

    #5647

    Curt
    Participant

    Leo69
    I get your point as I started down this same path but I very much doubt you will make anything near the quality and consistency as the JTech laser for $100. I am VERY happy with what I bought and I would not change it for anything. As far as the software I am sure there are free ones out there but I am not against supporting those who write software. Spending $30-40 for software is not the end of the world.
    Here is what I burnt today using the Laser Etch software. The smaller one (2″ wide) took 20 minutes and the larger one (4″ wide) took 40 minutes. I am still working out the lasing speed vs/ laser power.
    Curt

    #5673

    Ulli
    Participant

    If this is one’s first laser project, he or she should figure in at least 40+ $ for a pair of saftey goggles.

    #5674

    Leo69
    Participant

    Agreed. I think I spent $20 on mine but that’s the one thing that you may not want to skimp on.

    #5692

    karltinsly
    Participant

    Just thought I’d share a pic of how my laser looks on the universal mount at the moment. I will probably eventually replace the terminal block with some sort of quick disconnect, but for now it’s functional.
    KT Laser universal mount

    #5694

    Leo69
    Participant

    Karl did you design that mount? Those crosshair lasers are nice! What size heatsink would you say that’ll fit? I’m gonna have to make some time to print those nice quick release mounts I’ve seen and to get my laser on the mpcnc.

    #5695

    Leo69
    Participant

    This is a pic of my laser as it sits now. It’s a 9mm nichia ndb7875 2.8w laser module. I’m fairly certain the laser and the size of the heatsink would fit your mount without any modification. If it’s your design I’d really appreciate it if you shared the source file so i can tweak it to my needs. Let me know….thanks

    #5697

    Curt
    Participant

    Leo69
    I get your point as I started down this same path but I very much doubt you will make anything near the quality and consistency as the JTech laser for $100. I am VERY happy with what I bought and I would not change it for anything. As far as the software I am sure there are free ones out there but I am not against supporting those who write software. Spending $30-40 for software is not the end of the world.
    Here is what I burnt today using the Laser Etch software. The smaller one (2″ wide) took 20 minutes and the larger one (4″ wide) took 40 minutes. I am still working out the lasing speed vs/ laser power.
    Curt

    #5699

    karltinsly
    Participant

    Sorry Leo it’s not my design. I got it on thingiverse, and I believe it was created by ductsoup. All I did was join it with the universal mount and enlarge the line laser tubes. It is a cool design, though.

    I just looked, and ductsoup included .stp and .3dm files of it, if those help. It’s thing #1025450.

    #5704

    Ryan
    Keymaster

    Really make me want a laser with that pic. Laser etch the kit boxes before I ship them…

    #5706

    Curt
    Participant

    #5711

    Ryan
    Keymaster

    Leo69, it’s probably obvious I’m in your boat. I want to build everything I can. I have a bunch of old CPU heatsinks, and I own a mill 😉 So I think I might make an overkill heatsink and grab one of those lasers or maybe one of there giant 6W puppies! I see some of the lasers that come with the drivers take 6-9v are you using a separate power supply or is there a 12v driver? And since you have become one of our resident laser experts….do you know if those stronger diodes can handle a long enough duty cycle to etch with?

    #5716

    Leo69
    Participant

    Ryan,

    I personally use a 2.8w diode ,likely the same as Jtech does in their set-up but I didn’t buy it from Jtech. If anyone decides to go the DIY route then you’ll want the 2.8w Nichia NDB7875 module from DTR laser shop. This is a well reviewed and documented module among laser enthusiasts and DTR laser shop is also a reputable source in that community. Buy a fully assembled module to save yourself headaches. The NDB7875 module with a G2 lens(same one used by Jtech) is $90 or you can get it with a 3-element lens for $70. Both are good options and from what I’ve read the G2 lens will give you a slightly more powerful beam but a slightly larger spot size so a 3-element lens may be better for detailed work. I use the 3-element lens myself.

    You’ll need a 12v TTL driver with output up to 3amps to support that laser module. These can be found on ebay for about $8 . A heatsink can also be found there for another $6 or so. You should be able to connect the laser driver directly to a 12v output on your Ramps board so long as you’re MPCNC power supply has about 10amps or better. The laser should be tuned to run at about 2 amps and that leaves 8 amps left over for the MPCNC stepper motors which is PLENTY for most of our set-ups. The TTL input on the laser driver needs to be coonected to the fan outputs on the Ramps controller so that the M106 and M107 commands will drive it.

    I’m pretty busy these days but I WILL make time at some point to do a complete walkthrough for people interested in a laser set-up for under $100.

    #5720

    Ulli
    Participant

    Where’s the beef? Errr, the pic?

    #5723

    Leo69
    Participant

    Lol where’s the beef? Haven’t heard that in a long time. File attached…sorry. These laser modules and heatsinks all seem to be the same size which is nice.makes all the cool mounts everyone has designed more universal.

    #5725

    karltinsly
    Participant

    I’m having a hard time getting my laser focused. The setup guide says to turn down the laser output at the driver until the focus point is just bright enough to see, focus it, then turn the power back up to operating level. I’m sure this works, but really, I’m going to want to refocus each time I have a new work piece under the laser, and their method is too cumbersome.

    What I would rather do is use M106 to turn on the laser at a low power level so I can focus it whenever I want. I tried doing this by creating several files similar to this one:

    M106 S10
    M25
    M106 S00

    The idea here is bring the laser up at a given level and pause, then after focusing, resume the burn and the laser turns off. What’s happening, though, is that either the laser blinks on and off and that’s it, or the laser comes on at the specified level and stays on, but the file just ends, so there’s no resuming and turning off the laser. I also have tried as laser off file, with both M106 S00 and M107 commands, but running it doesn’t turn off the laser.

    So anyway, I’m able to turn the laser on at low power and focus it, and get it to turn off, which is what I wanted, but does anyone know why my files do not act as I expect?

    I’m running the files off an SD card and LCD.

    Karl

    #5727

    Leo69
    Participant

    These lasers should focus to a point at a working distance of about 50mm. I think the easiest thing to do is fire up your 3d printed and create a simple ruler/standard that measures 50mm, maybe add some legs so it can stand on it’s own on your work surface. Then put this ruler on your work surface and bring the laser down until it just touches it. The end of your laser should have a knurled cap that holds the lens in place(spring loaded). You have a few turns of thread here to fine adjust the focus point at that work distance. That distance will always be fixed so you can just ‘zero’ your laser z height against your rule before you burn from then on.

    Before you create anything , take a ruler and confirm that your focal distance is close to 50mm. It has to be pretty close to start with because there isn’t that much adjustment room on the lens assembly.

    #5728

    Leo69
    Participant

    I should also mention that you don’t want to be bumping the lens against anything, just the heatsink.

    #5730

    Curt
    Participant

    Karl
    Use the control temperature feature and turn your fan on to 15 to get the laser on at low power. I do this anytime I remount the laser after setting my height.
    Curt

    #5734

    karltinsly
    Participant

    Curt – is the control temperature feature something on the LCD menus? I’d check myself but the MPCNC’s lasing another project 🙂

    Leo – is 50mm the right focal distance for the JTP laser? I thought their website recommended around 30mm, but someone also pointed out that in their videos, the focal length seems much greater. I think I will try focusing to 50mm for my next burn.

    Thanks, both of you for your input!

    #5736

    Leo69
    Participant

    My laser set-up isn’t on an MPCNC (yet…) and doesn’t even have a Z-axis. I adjust my Z with a couple of set screws before each burn. The distance where the beam focuses at it’s smallest point will vary depending on which lens you have but my point is that this distance is fixed and once you know what that distance is you can create a “gauge” to quickly set the laser from the work surface by that same amount of distance each and every time. That way you can set your Z laser distance from the work surface without even turning the laser on. When I set my laser I just loosen the set screws and drop the laser heatsink onto my “gauge”. Then I just tighten the set screws and I’m done.

    As far as finding that perfect focus distance goes, I think the Jtech site makes a good suggestion about turning the beam power really low. I also found that a matte black or gray surface is best for focusing the spot size. It’s hard to tell how small the spot is on a bright or reflective surface. If the power is really low, like M106 S10 or S5, you can take the laser goggles off and look at it directly without frying your retina. Very hard to see the laser at low power with the goggles on.

    The order you choose is up to you. You can set the focus, measure it and then create a gauge to match or you can work backwards. Create the gage and try to get the focus distance set tp the same as the gage by using the fine adjustment on the lens cap. I went the second route because all I had was a ruler and it was hard to measure a straight distance with obstacles in my way.

    #5737

    karltinsly
    Participant

    Thanks, Leo. I agree that getting focused at a specific length and then just setting that distance for each new surface is the way to go – I certainly plan to create some kind of gage to do that. Thanks for the tip on using black or gray for focusing!

Viewing 30 posts - 31 through 60 (of 94 total)

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