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Diode lasers for plywood cutting

Discussion in 'Laser Cutters' started by Anelito, May 21, 2020.

  1. Rob Taylor

    Rob Taylor Veteran
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    15-20W nominal is about 6.5W actual. There is no current diode rated higher than this. I would expect, with a good air nozzle, them to be able to cut thin balsa, maybe up to 1/16", in one, maybe two passes. Plywood, no chance, though I'd look into the possibility of them doing it in 5-6 passes.

    They're not toys, but they're also not for heavy fabrication. They excel with paper, fabric, veneers, non-transparent sub-1.5mm sheet plastics (or transparent with the film sprayed black to catch the light), etc. I use my 1.6W laser to cut stencils and recently fabric for masks. It's super handy.

    But it's not a 60W CO2 laser. Plywood and acrylic, that's what you need.
     
  2. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
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    445nm lasers absorb (read does its job on) well into Organics (wood, paper, leather) but not in any kind of plastic/resin/etc - CO2 lasers with the smaller 10600um wavelength absorbs better into all kinds of materials.
    With plywood the problem is the PLY part of the word... its layers of organics (wood) glued together with Inorganic resins - so running a diode laser to cut plywood (even 3mm thick plywood consisting of three layers) fails because you "cut" (more like slowly scorch through though as the diode lasers are weak anyway) the first layer of wood, but then when it gets to the resin glue between the two layers, you get stuck and spend pass after pass trying to get through the glue line. But the time you did burn away the glue layer, all that heat has scorched the edge of the layer of wood above it beyond what it should look like.

    A piece of 3mm solid balsa, yeah, with enough passes, good focus and a Z axis to do stepdown to keep the focal spot on the right depth for each pass, you can cut wood - but yeah, if cutting is the game, get a CO2 (or cut with a CNC router) and keep the diode lasers for engravings (their linear power control makes them awesome for engravings, you can get photo quality grayscales out of them)
     
  3. Anelito

    Anelito New
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    Actually, a friend of mine was able to cut 3mm plywood using a custom-made air nozzle and a 5.5W (optical output) diode laser. I am quite concerned his successful result was just due to the type of wood used and may not be reproducible with the one I can get off-the-shelf.
    Can a K40 or similar cheap CO2 cutter be disassembled and readapted to support a larger cutting area?
     
  4. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
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    6w is the limit of diode technology at the moment, anything more is "marketing" (;

    Fair enough it can be done, the question is done to show you can, or done as in "this worked great" - question is what kind of feedrate, how many passes, etc.
    Air nozzle helps to blow up the carbonised residue, so yes, air assist is a good thing

    Speaking of marketing, see

    https://optlasers.com/manual/laser-head-test-1-plh3d-6w-optlasers.com.pdf and https://optlasers.com/manual/laser-head-test-2-plh3d-6w-optlasers.com.pdf for some quoted feedrates/capabilites of OPTlaser's 6w lasers. There is a test of 3mm plywood in there: 10mm/s (600mm/min) and 10 passes at 0.3mm each (they say) - if you instead cut that on a CNC with a 1/8th endmill, you could run 1500mm/min and 2 passes (about 10-15x faster)
     
  5. Rob Taylor

    Rob Taylor Veteran
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    In one pass that would be extremely impressive. Couldn't comment much without more details about the setup and the circumstances though.

    Yes. That gets you a 30W tube, PSU, mirrors, maybe a chiller and coolant plumbing. The rest of it you can basically turf, and replace with V-Slot. Might be cheaper to completely scratch-build at that point.
     
  6. Anelito

    Anelito New
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    It's a NEJE 20W (output 5.5) at 10cm distance and 100% power, in two passes. I'll ask the permission and share the video with you.
    If it turns to be possible, I'd be paying less than $300 for a laser cutter able to slice 3-4mm plywood. Otherwise, I think using online service is more suited as A3-sized CO2 laser cutters are way out of my budget.
     
    #7 Anelito, May 21, 2020
    Last edited by a moderator: May 21, 2020
  7. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
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    I don't know if they still do, but a while back that company had an overdrive driver on those modules (I had one myself): Instead of powering the diode continuously with a current-limited driver, it instead pulsed the diode without current protection, only relying on its initial high resistance to not burn out, to get high peak output for short bursts to "cut" better - I think they even had a warning saying "only suitable for cutting not for engraving" or something like that - sadly that style of driving shortens the diode life to around 80-100 hours. The better designed drivers power the diode with proper current limiting, for thousands of hours of diode life. Only mentioning this so the "cheap" module is seen as a consumable
    Also, those drivers don't do PWM well, so you loose some flexibility (can't use it for engravings too)

    Easy to see if you look at a cut video (camera settings dependant of course), the camera tends to look a bit stobe-ey from the pulsing
     
  8. Rob Taylor

    Rob Taylor Veteran
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    I have looked at the 4.5-5.5W units like the NUBM08 periodically, since my BlackBuck 8M can drive them too (though I'd have to add active cooling, I'm sure). 1.6W isn't as impressive as it was in 2016 when I started my build, but it does the job I need it to. Would be nice to be able to occasionally throw some slightly chunkier sheet materials in there though. When the current NDB7875 unit dies maybe I'll upgrade. It's only about a $15 difference on the TO5 canister packages.

    Yeah that seems like a horrible idea. :D
     
  9. gattis

    gattis New
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    Most powerful diode laser is the nubm44-v2 (aka nubm47?) rated at 7W. Anyone claiming higher than that in a diode is fudging the numbers.

    Only one I could find for sale in a full module with lens, fan, heatsink and ttl driver is here 7W - 15W CNC Laser Engraving Module w/ Driver, G-7 Lens & Turbo Fan - NUBM44-V2 | eBay

    On the fence but think I'm going to grab one. Listing says it can be pulsed to 15W. I'd estimate you could realistically cut 4-5mm of plywood or bamboo.
     
  10. josejvargas

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  11. gattis

    gattis New
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    watch this youtube vid

    he cuts 5mm plywood with a 4W laser in 12 passes. For whatever reason these blue diode lasers actually seem to excel at plywood over any kind of solid wood.
     
  12. Rob Taylor

    Rob Taylor Veteran
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    Yep!

    Barnett's got a fair chunk of change out of me over the last few years thanks to the bad driver I bought from them. I don't think it was their fault, I just got a bad unit of a less-than-stellar product. I've looked at that listing before though, should be a solid laser unit but I'm not sure I'd trust another unlabelled driver, if such it is. I'd go with a BlackBuck, a DTR X-Driver, something well-known in laser-forum-land.

    Exactly, no chance. Within the context of the original claim, I was expecting 1-2 passes. I wouldn't call more than five actually successfully cutting something, and even that's pushing it. Probably three, to actually be useful for production.
     
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  13. JustinTime

    JustinTime Journeyman
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    For production, I agree, not worth it. If you do production it infers that it's going to be making income so invest some more money in your 'business'. For the hobbyist, like me, for example, 12 passes may take a long time but I do it only once in a while so maybe the cost savings are a good option.

    Time I have lots it's money I'm short of! :ROFL::ROFL:
     
  14. Gary Caruso

    Gary Caruso OpenBuilds Team
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    To cut wood with a laser you really need an "air blast" to clear the smoke, and more than 1 pass ends up with nasty char on the edges.. my experience with laser cutting (i've sourced laser work with several companies) is that 40watt CO2 is what you want for 1/8" birch ply and up to 5/16" balsa (1/2 Balsa can be done but it's not easy).. I used one guy who made excellent kits with 20watts CO2 but setup was super critical. Plywood is the hardest, the glue scatters the beam, or something.
    Gary
     

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  15. romamaker

    romamaker New
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    You can go thicker then 1/8" with 40W. I've done a bunch of 1/4" birch ply with a 40W. 1 pass, no charring. Might be able to go more, but I've never had the need. But to echo others, CO2 is the way to go if you want to cut.
     
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  16. Rob Taylor

    Rob Taylor Veteran
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    Nice to see real practical experiences.

    40W CO2 is also in a pretty good sweet spot, price-wise, to DIY. The 1m tube lengths and 40-60W ranged PSUs also allow for convenient upgrade later, if desired. I wouldn't be surprised if I ended up doing a build like that at some point in the next couple years or so, it opens up a whole world of opportunities.
     

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