Cutting foam sheets... with a needle!
- Thread starter dkj4linux
- Start date
dkj4linux
Elite member
Hey, Mike! The cut starts bottom-left corner of all figures and proceeds clock-wise. So the "sharp end" (the tapered section) is the beginning of the cut... when the speed should be ramping up. The end of the cut looks like it came back to the exact starting point. My understanding is that GRBL laser mode and M4 ramps the power up when accelerating... and ramps power down when it decelerates. I guess I expected those to be more symmetrical but they're not... so I think the "flaw" is in my thinking/ignorance of all the various settings involved in Lightburn and Grbl. I'm sure they are doing exactly what they are being told to do...
dkj4linux
Elite member
No, you're correct, M3 is the right command for this project. I've successfully cut these with Marlin and M106/M107 before... and that's just a simple constant power command, similar to Grbl's M3. I don't think M4's dynamic power adjustment is the appropriate action -- based on what I've seen here -- for through cuts and closed shapes. But for some odd reason, even M3 is not completely closing the figure... better than M4 but still a small gap. My workaround for now is to simply make 2 passes for the holes and profile cuts... the 2nd pass just to cut the tiny tab. Unfortunately that also greatly increases the chances of starting a fire in this thin material. Ask me how I know...
Now what box did I put that little fan in?
Now what box did I put that little fan in?
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Springer
Member
I'm waiting at secretary of state to renew car tags, found this page that may help: https://github.com/gnea/grbl/wiki/Grbl-v1.1-Laser-Mode the M4 dynamic sounds fraught with confusing opportunities! The mention that one has to turn M3 on and off at the right time. So far it has always worked correctly for me. I also looked at Lightburn, an interesting program to allow raster and vector on same job. So far I am just using Su and wafer to generate my code, and add the laser on off manually by editing in notepad since I discovered it has a <replace all> option. Every S change is the same, so it has been easy. I am burning sayings on slices of wood branches (end grain all vector, no raster). I'll post a pic or two.
Springer
Member
Just looked again at your picture! Oops! Yup need to turn off at right time! One interesting thing I noticed is MPF is a perfect spoiler board for laser work. The beam just lights it up, diffusing into a round circle but not burning. (Which would be really unfortunate if not for the needle cutter!
dkj4linux
Elite member
I'm not sure a solid spoiler board is best for this -- even if it doesn't burn -- unless it allows for some air flow underneath. A bed of nails or light metal gridwork of some sort. that holds the workpiece suspended in the air, allows air flow underneath to carry away the smoke and soot... and the bottom-side stays cleaner. That's what you see in most of the commercial machines out there, I think. I also had a little experience with this as well, in this very thread, when I first started playing with lasers... check this post and following to see the fun we had...Just looked again at your picture! Oops! Yup need to turn off at right time! One interesting thing I noticed is MPF is a perfect spoiler board for laser work. The beam just lights it up, diffusing into a round circle but not burning. (Which would be really unfortunate if not for the needle cutter!
Springer
Member
(Long delay in reply!) In my case, since I don't need the vac table to hold pieces down with laser (as opposed to needler), I hold the shop back close to the work piece to suck up smoke. That seems to work fine for me with the MPF spoiler board. I cut through 3mm ply for a servo mount ( must have taken 10 passes!). As it cut I saw some flame, but the suction seemed to quench it. When it cut the last few layers and I had intermittent burn through, I could easily see them as the MPF lit up, but it never penetrated it or ignited it.
Wildthing
Legendary member
The lasers don't reflect off of white that's why it works great as a spoiler, I have white foam under mine also and just once in awhile the laser will penetrate the foam but it has never gone through all the way. . If you have some grey foam though watch it cut it like butter
dkj4linux
Elite member
OK. When I last left off in my UN-closed closed-figures saga…
Once I delivered my daughter’s little T8 Mini-mill, turned laser engraver… I dragged out an Eleksmaker A3 3.5 watt laser machine I had built up before. Got it set up and running with Mega/RAMPS/Marlin — as before — and then went to my stash and found a Uno/CNCshieldV3 board set to play with. Converted the Eleksmaker to a Grbl v1.1h set up… and hooked up the 3.5 watt Banggood laser it had mounted.
What do you know? This unit seems to handle every previously-problematic test case without difficulty... all closed-figures are closed. Not a problem at all. So Lightburn is fine… and Grbl is fine. Apparently the CNC processor/controller and/or laser driver are the culprit(s). Note the M3 and M4 labels in the following photos… in Grbl 1.1h laser mode, M3 is the CONSTANT power mode and M4 is the newer DYNAMIC power mode. Look closely at the corners… and note the darker M3 burns (first photo left) whereas the M4 burns (right) show the effect of reducing power as each cut accelerates and decelerates at the corners.
I think I’m going to tidy this machine up and swap out my daughter’s machine. She said she prefers Lightburn’s all-in-one, ease of use, features over Inkscape/Jtech and is looking forward to the larger work area of the Eleksmaker machine.
This machine seems so much better behaved and, being belt-driven, is very much quieter. And, for the first time, I'm able to get some decent images out of Lighburn, that actually match pretty closely those I got from Victor’s ImageToGcode for the same feed, power, resolution settings (“Laser engraving – not really getting great results” MPCNC/V1Engineering thread)…
The black stripe in the following photo is where my PWM’s GND wire pulled loose from the pin on the controller… and the laser was then on full-blast. Be careful with these things, folks!
I continue to be impressed by that inexpensive little CNC V3 shield… it is so simple and versatile. I had used it, without the Uno, for my Inexpensive LinuxCNC Interface board set and it was perfect for that application… and it is, here, as well IMHO. It uses the same little step-stick drivers we all know and love, the fourth driver is easily jumpered to clone any axis or be independent, and hooking a laser to this thing is dead-simple (if you need +5v PWM, verified with a scope)…. just use Grbl 1.1 or later and use the Z+ and GND for PWM (right-most green and blue wires), with no pin remapping necessary…
I’m really wondering now if this controller set CLOSES my closed-shapes because the PWM pin (Z+) for laser control is a simple, straight (wire only), connection to the D11 pin on the Arduino. The other CNC1610 boardset (the one with the problem?) I used is an integrated controller (which I haven’t probed and have no schematic for) and has connector “ports” for laser power and modulation. Maybe there’s some “funky” circuitry between the Arduino and PWM connector pin that causes some [integrated?] controllers to exhibit the problem? Or, it could be the laser’s driver board, I think… I’ve got another 2.5 watt Eleksmaker laser ordered, so maybe we’ll see.
Anyway, I am really starting to like Grbl 1.1 (with laser mode M3/M4 control) with this simple Uno/CNCshield boardset… and Lightburn seems to generate gcode that works well with it. It also helps that it has my daughter’s “stamp of approval", so...
All is right in my world again… and I am at peace 😉
— David
Once I delivered my daughter’s little T8 Mini-mill, turned laser engraver… I dragged out an Eleksmaker A3 3.5 watt laser machine I had built up before. Got it set up and running with Mega/RAMPS/Marlin — as before — and then went to my stash and found a Uno/CNCshieldV3 board set to play with. Converted the Eleksmaker to a Grbl v1.1h set up… and hooked up the 3.5 watt Banggood laser it had mounted.
What do you know? This unit seems to handle every previously-problematic test case without difficulty... all closed-figures are closed. Not a problem at all. So Lightburn is fine… and Grbl is fine. Apparently the CNC processor/controller and/or laser driver are the culprit(s). Note the M3 and M4 labels in the following photos… in Grbl 1.1h laser mode, M3 is the CONSTANT power mode and M4 is the newer DYNAMIC power mode. Look closely at the corners… and note the darker M3 burns (first photo left) whereas the M4 burns (right) show the effect of reducing power as each cut accelerates and decelerates at the corners.
I think I’m going to tidy this machine up and swap out my daughter’s machine. She said she prefers Lightburn’s all-in-one, ease of use, features over Inkscape/Jtech and is looking forward to the larger work area of the Eleksmaker machine.
This machine seems so much better behaved and, being belt-driven, is very much quieter. And, for the first time, I'm able to get some decent images out of Lighburn, that actually match pretty closely those I got from Victor’s ImageToGcode for the same feed, power, resolution settings (“Laser engraving – not really getting great results” MPCNC/V1Engineering thread)…
The black stripe in the following photo is where my PWM’s GND wire pulled loose from the pin on the controller… and the laser was then on full-blast. Be careful with these things, folks!
I continue to be impressed by that inexpensive little CNC V3 shield… it is so simple and versatile. I had used it, without the Uno, for my Inexpensive LinuxCNC Interface board set and it was perfect for that application… and it is, here, as well IMHO. It uses the same little step-stick drivers we all know and love, the fourth driver is easily jumpered to clone any axis or be independent, and hooking a laser to this thing is dead-simple (if you need +5v PWM, verified with a scope)…. just use Grbl 1.1 or later and use the Z+ and GND for PWM (right-most green and blue wires), with no pin remapping necessary…
I’m really wondering now if this controller set CLOSES my closed-shapes because the PWM pin (Z+) for laser control is a simple, straight (wire only), connection to the D11 pin on the Arduino. The other CNC1610 boardset (the one with the problem?) I used is an integrated controller (which I haven’t probed and have no schematic for) and has connector “ports” for laser power and modulation. Maybe there’s some “funky” circuitry between the Arduino and PWM connector pin that causes some [integrated?] controllers to exhibit the problem? Or, it could be the laser’s driver board, I think… I’ve got another 2.5 watt Eleksmaker laser ordered, so maybe we’ll see.
Anyway, I am really starting to like Grbl 1.1 (with laser mode M3/M4 control) with this simple Uno/CNCshield boardset… and Lightburn seems to generate gcode that works well with it. It also helps that it has my daughter’s “stamp of approval", so...
All is right in my world again… and I am at peace 😉
— David
Hello guys I just want to thank to all of you for all information in this thread and for mastering this great way to manufacture planes at home. 🏡 Today I finished my needle cutter and it's running very smooth, I'm really happy! Can't wait for first cuts foamboard is on its way to my door, hope it's the right type. In Europe is almost impossible to buy FT foam board, but on Amazon I found something looking very similar.
I just want to thank to all of you for all information in this thread and for mastering this great way to manufacture planes at home. 🏡 Today I finished my needle cutter and it's running very smooth, I'm really happy! Can't wait for first cuts foamboard is on its way to my door, hope it's the right type. In Europe is almost impossible to buy FT foam board, but on Amazon I found something looking very similar.
dkj4linux
Elite member
I'm not sure whether this was ever fully developed but the idea of a handheld cutter has been brought up a few times. AFAIK this one came closest to being a practical cutter...
dkj4linux
Elite member
No, I'm sorry. I didn't see your question... I'm really not a FB kinda guy. I feel much more at home here in the forums.
He showed up here a few weeks ago and I've now got a kit coming from him. I've already ordered and received some extrusions. But I've also got several projects going at the moment, so I'm not sure when I'll get around to putting it together. I've often thought I'd build a machine similar to this one from Tom McGuire (who was the inspiration for my free-running needle cutter for general-purpose 3-axis CNC machines)
or similar to a drawing machine like AxiDraw... but Edward's machine is a distinct improvement over anything I'd envisioned so it definitely seems the way to go.
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sooriginl
New member
Thanks! Maybe handy for complex inside curves.
CMS_1961
CMS_1961
Hey Edwardchew,
Really like the machine you have made and would like to purchase a kit. I joined your facebook group buy I am lost in there--never used facebook and have no idea where to order a kit from or how to navigate in that discussion??? For the flitetest people, could you post the information on how to order a kit here so those that are not part of the facebook world (me) could get a kit.
Thank You,
Chalie
Really like the machine you have made and would like to purchase a kit. I joined your facebook group buy I am lost in there--never used facebook and have no idea where to order a kit from or how to navigate in that discussion??? For the flitetest people, could you post the information on how to order a kit here so those that are not part of the facebook world (me) could get a kit.
Thank You,
Chalie
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