Cutting foam sheets... with a needle!

[dkj4linux]

Great progress, Dave. I haven't been bold enough to play with stainless or vinyl yet.

I repeated my test with the F4 "engraving" on frozen pizza box cardboard. Kept full power but set best focus and bumped the feed rate up to 1500 mm/min with far better detail in small areas...







but, alas... still too much power to qualify as "engraving" on this thin cardboard



-- David

 

[RAGII]

Hey guys, I was reading over on the Vicious site that one of the laser users added air assist and it greatly increased the quality of the burn. http://www.vicious1.com/forum/topic/simple-air-assist-for-laser-work-is-surprisingly-effective/

You might want to play around with that and see what results you get.

Rob

 

[dkj4linux]

First photo test using image2gcode...

 

[wild.bill]

Hi guy's

I have been following this thread for almost a year and if I ever posted anything it was not much. I started following because I had built a 24" x 36" laser cutter to cut planes from DTFB with. I had the same issues you guts have with it not cutting the bottom layer. I have built the parts to do the needle cutter but but off into other project and never installed them. In keeping with all the toys you have talked about I have the laser cutter, 3 3D printers and am in the process of building a CNC platform that I will mount a rotor and another laser. All of them have been built with 2020 rails.

With the laser I have a number of controller boards and have been using ELEKS L6 board and a UNO/CNC Shield board with GBRL. For the laser I have the Banggood 2.0W TTL laser. Now that you are talking about engraving I finally have something that I can add. The latest GBRL release has added better support for Lasers and you can get some very nice images. For the images I have been using T2 - which works with GBRL but not Marlin at this time. I don't know if you know about this forum http://benboxlaser.us/index.php which has lots of great information. The guy's on that forum have written user code for engraving (T2) and for cutting BenCutLaser which does work with Marlin/ramps boards.

Here is an image I made the other day using the T2 software. Burnt into word that was used as a layer separator in a cigar box. I can get better images on cardboard than this wood but I didn't have any more cardboard at hand. Being a retired engineer the image is fitting most morning while I plan the day.

 

[dkj4linux]

That looks really nice, wild.bill. That was my first attempt at engraving a photo. I actually used the default levels for "wood" on that thin pizza-box cardboard... looks like I need to move closer to the "vaporize bulldozer" settings

I've visited over on that forum a couple of times but never lingered long enough to see what all was there. There's a similar forum revolving around the MPCNC, which many of us here have built, and there's a MPCNC-specific version of the Image2gcode software that a couple of sharp fellows have been working on... so I really want to give it a proper go. I'll be tickled to get an engraving as nice as the one you show. BTW I'm a retired electrical engineer as well and can relate to the image... and morning routine -- David

 

[GremlinRC]

Hi Wild Bill. That is really first rate. Gave me a good giggle too!! Thanks for jumping in. We have a right laser crew here now!

Hi Rob: I was just thinking about air cooling. My safety goggles are pretty dense so I just see a bright spot through them, but I can still see little shards of laser light bouncing off smoke particles. I think for simple tests I could cable tie up my airbrush which should allow some good comparitives. I'll get cracking on that tomorrow and see how it goes. I the longer term I'd like to tie this in with an extraction system too. I was messing around with lots of material today including foamboard and I did not like one little bit the smell coming off the burned foam. I certainly wouldn't want to release large quantities of that in my workshop.


..anyways as mentioned I was messing around with anything I could find with mixed success.

Clear Acrylic: Fail. The last just passes straight through and burns the spoilboard which in turn melts the underside of the acrylic but not in any useful way (sorry havent got a photo).

Aluminium Foil: Fail. Doesn't even mark. Even full power 50mm/min and 10 passes

Clear PETG: Fail. Same as clear acrylic.

Balsa: Big success. 300mm/min full power 1 pass. I can definitely see me getting into a bit of balsa bashing after this success.



FliteTest Waterproof Foam Board. Cuts ok but leaves too much of an undercut to make this a viable alternative to the needle cutter.

400mm/Min, 100%, just cut through the paper and left a channel exactly like the rightmost cut in the image below.

200mm/min (pic below) 1pass (righmost) through 5 passes leftmost. Might be interesting to try again with an airblast and see if that helps. I should mention this was just sitting on MDF hence the lower paper burn in.



Posterboard: cuts a dream at 700mm/min, 1 pass, 75% power. (Sorry no pic).

I use Mach3 and it doesn't work very well with image2gcode. However I came across a Mach3 plugin to rasterise images via a laser so I'll have a play with that tomorrow and see what damage I can do.

Finally I'd just like to wish you and your families a safe, peaceful and healthy 2017. I wish you all lots of cool gadgets and look forward to sharing lots more experiments!

 

[wild.bill]

The coffee must be an EE things - that is what I am - a retired EE (but don't tell anyone).

In the past I had used a separate fan to clear the smoke, but upgrading to the 2watt TTL laser was a good move. In addition to having a much better lens to get a very fine dot it also has a high volume fan that puts so much air by the laser it also keeps the smoke away. I have not used the external fan since I installed it.

I have found that clear plastic of any type cuts very poorly. The only thing that is clear that I have had any luck with is etching glass and mirrors. I run at 200mm/min for glass.

I never had much luck cutting any foam board, it would cut the upper layers with no problem but always left the bottom layer intact.

And for speed the image that I showed earlier was done at 2500mm/min. For reference I do cardboard at 1500 - 1800 mm/min. The softwood etches real easy.

Hope everyone has a happy and safe new year.

 

[dkj4linux]

The coffee must be an EE things - that is what I am - a retired EE (but don't tell anyone).

In the past I had used a separate fan to clear the smoke, but upgrading to the 2watt TTL laser was a good move. In addition to having a much better lens to get a very fine dot it also has a high volume fan that puts so much air by the laser it also keeps the smoke away. I have not used the external fan since I installed it.

I have found that clear plastic of any type cuts very poorly. The only thing that is clear that I have had any luck with is etching glass and mirrors. I run at 200mm/min for glass.

I never had much luck cutting any foam board, it would cut the upper layers with no problem but always left the bottom layer intact.

And for speed the image that I showed earlier was done at 2500mm/min. For reference I do cardboard at 1500 - 1800 mm/min. The softwood etches real easy.

Hope everyone has a happy and safe new year.

Back at you, WildBill, retired EE (but I won't tell anyone)...



This was done in about 40 minutes using Image2gcode... 60% power max, 3000 mm/min, and same cardboard. Not quite "vaporize bulldozer" but better...

And then, again, at 75% power (upper image)...



And, finally, 100% power (far left)... sorry 'bout the photo disorientation but it looks as though I'm safe just using max power and 3000 mm/min for engraving cereal- and pizza-box cardboard...





And a short video of the first run...

Google was, once again, my friend and saved me asking you if you could send that image to me. Ain't technology wonderful? And good friends...

Thanks, guys.... one and all. This is fun... let's keep it up. Merry New Year, all! -- David

 

[GremlinRC]

Some tests this morning with an air blast hose. I rigged up this rather heath-robinson arrangement with some silicone hose a beach ball inflation needle (as recommended on the vicious1 forum) and my airbrish compressor.



First up was the foamboard. Same settings as the pic in my previous post (200mm min, 100%) but with air blast. The difference is striking. The single pass (right) of course cut the paper. But the 2 and 3 pass lines hardly made any difference. the 4 pass run was making an impact but the problem of melting really occurs when the paper burns hot as it did on the 5 pass run (left).



Next up was balsa and as you can see the difference is remarkable. I have an issue where there is about a one second delay from the first time the laser starts until motion starts, the result is a wide burn spot, but as you can see this is significantly reduced with air cooling.



If I remove the parts and turn them unpside down, you can see that the air is blwing the smoke across the bottom of the part and staining. I think air is needed top and bottom, now I just have to figure out a way to do that!

 

[wild.bill]

I am not pushing any specific software, just saying what I have been using and what works for me.
I am using a controller that is supported by GBRL and I really like the new 1.1 GBRL release because of the laser support that was added.

First when the laser comes on for a second before moving that is an artifact of being CNC software, it is waiting for the spindle to spin up prior to starting the motion.

The second thing that I really like when printing images is Dynamic Laser Power. There is acceleration with these machines so when the gantry first starts moving it not moving as fast at the start as it is in the middle of a leg which can lead to some burning at the ends of a line. With the Dynamic Laser Power the controller ramps the laser power up/down with the acceleration and eliminates the burns at the end of lines.

So I jumped into inkscape and made a little star to burn and you can see that there are no burn marks where the laser was at the start of the cut. I was a vector file so no DLP was needed. And nothing like going off the edge of the balsa when trying to make an example - OH Well.

 

[dkj4linux]

I am not pushing any specific software, just saying what I have been using and what works for me.
I am using a controller that is supported by GBRL and I really like the new 1.1 GBRL release because of the laser support that was added.

Wild.Bill, I knew you weren't pushing a specific software and wasn't trying to "one up" you, saying my software's better than your software. I think we were all impressed with the Garfield engraving you showed... and I'd already said I'd be tickled to have my engravings look as good. So I Google'd and found your image to use as a "standard" image (rather than a personal photo) to further test my engravings. No offense intended.

While both my current MPCNC's are "stock" and use the Mega/RAMPS combo, I have used GRBL-based Uno/Gshield combos on a couple of other CNC's I've built... including a Shapeoko2 that my son now has. I've also used EMC2/LinuxCNC and HobbyCNC driver boards with a couple of old leadscrew-driven BuildYourCNC-based machines that I've shown needle-cutting planes from several years ago... so am aware that the CAD/CAM software and gcode post-processors you use are pretty much determined by the board set choices you've made.

Everything you said about the "power on delay" (before movement) and acceleration/deceleration is true. It's amazing that with a laser such short-duration events as simply a change of direction will leave a little divot in the corner. So much to learn and consider when using it is what makes the laser such a fun toy to play with.

Again, I value your input concerning your experiences with the tools you're using... please keep sharing. We all learn something when folks are willing to share their experiences... and the affordable choices we have today -- in machines and software -- are better than ever. It's an exciting time we live in... -- David

 

[GremlinRC]

Everything you said about the "power on delay" (before movement) and acceleration/deceleration is true. It's amazing that with a laser such short-duration events as simply a change of direction will leave a little divot in the corner.

Indeed it is true and like a switch on a relay, Wild Bill's wisdom made me twig exactly why I was getting that 1 second delay between power on and motion. It's a setting in Mach3 which defaults to 1 second. Changed it to zero and the delay is gone

I've moved my laser onto my smaller but ballscrew driven CNC. I have an issue with the Y axis on my foamboard CNC machine which will need some attention. I may well replace the acme screw with a GT2 belt drive as the acme screw severely limits my top speed on that axis anyway.

I've been playing with ABS with some very good success. Some pics later. Again the air shot makes a huge difference.

From my initial tests I'd say go set up an air shot, from my tests today it is the single biggest improvement you can get.

 

[wild.bill]

I had my compressor in the room with the laser for a while but didn't like the noise so I went to a low tech method of blowing the smoke away- see the picture. You can also see the low tech method of holding the cardboard down. This was an earlier time when I was using a 1.6 watt laser which I liked because it also had a very fine dot.

When you say ABS I am assuming you mean with the 3D printer. That is what I started with and about all I ever print with. I did a little with PLA but I had alreay dialed in the ABS so I always got better prints with ABS so I stopped using the PLA.

 

[GremlinRC]

When you say ABS I am assuming you mean with the 3D printer.

No I meant cutting abs with the laser. If ever a picture told a thousand words its the one below with and without air cooling. I don't think I need say which one was air cooled. This was 7 passes 300mm/min 100%. Black ABS cuts better and in 3 passes. The material is 2.5mm thick. Without the cooling the material caught fire a couple of times and produced thick black smoke which just did not happen with the air cooling.



Cheers

Dave.

 

[wild.bill]

OK - I think I will stay with printing ABS and stay away from cutting it. The air probably cools the plastic quickly after the laser beam has gone by. My wife is never happy when I make a lot of smoke.

 

[dkj4linux]

Guys,

I'm not really sure yet what kind of air movement you're talking about with this "air assist" thing. There's no doubt from the pictures you've shown, Dave, that the air-assist has made for far cleaner cuts... but I also see that neither you nor WildBill has a housing of any sort around your laser. I've been pretty pleased overall with the cleanliness of most of the cuts I've made -- and I've never had any as ugly as those "before/without" pictures you've shown, Dave -- but I've also got a printed housing completely enclosing my setup. There's a 40mm fan near the top of the housing, blowing air down through the housing and across my driver and laser/heatsink, and out through the nozzle... completely surrounding the beam. Not a hurricane, mind you... but enough to clear the smoke pretty effectively, it seems to me. I've rarely seen a solid beam (from smoke) when properly focused on the material.

So my question is this... does what I have qualify as "air-assist"? Or, do I need to be doing more to see a dramatic improvement?

-- David

 

[GremlinRC]

So my question is this... does what I have qualify as "air-assist"? Or, do I need to be doing more to see a dramatic improvement?

-- David

Your right, I've got no enclosure yet, until I get my 3d printer. Mine has a 40mm fan too and it blows the air straight down across the cooling fins of the module but of course the diode itself prevents it blowing directly onto the hotspot. My air assist is an airbrush compressor hooked up to a silicone hose terminated at a beach ball inflator needle just a couple of mm away from the hotspot. I pretty much just did exactly what the guy on the vicious1 forum did. Having such a powerful air jet so close to the burn point also seems to clear away any ash. I can see little flecks of burning ash being ejected clear of the cut, which I guess helps a lot on multiple pass cuts.

David I notice your enclosure tapers in a good bit at the end which should direct a lot of the air to the laser spot. BTW is that your own design or did you find it on thingverse?

I know for sure that I'm gonna design my hood to allow a needle be inserted to get that really fine air blast right onto the laser spot.

 

[GremlinRC]

OK - I think I will stay with printing ABS and stay away from cutting it. The air probably cools the plastic quickly after the laser beam has gone by. My wife is never happy when I make a lot of smoke.

Good plan! If you're set up in the house stay well clear of the plastics, your good lady wife will not be impressed!

Cheers,

Dave.

 

[dkj4linux]

Your right, I've got no enclosure yet, until I get my 3d printer. Mine has a 40mm fan too and it blows the air straight down across the cooling fins of the module but of course the diode itself prevents it blowing directly onto the hotspot. My air assist is an airbrush compressor hooked up to a silicone hose terminated at a beach ball inflator needle just a couple of mm away from the hotspot. I pretty much just did exactly what the guy on the vicious1 forum did. Having such a powerful air jet so close to the burn point also seems to clear away any ash. I can see little flecks of burning ash being ejected clear of the cut, which I guess helps a lot on multiple pass cuts.

David I notice your enclosure tapers in a good bit at the end which should direct a lot of the air to the laser spot. BTW is that your own design or did you find it on thingverse?

I know for sure that I'm gonna design my hood to allow a needle be inserted to get that really fine air blast right onto the laser spot.

Dave,

I used Allted's housing design since I was using similar components... but I used Tinkercad to modify it so that it has the Hicwic's quick change mount like the rest of my tool mounts. You can see it here...

http://www.thingiverse.com/thing:1636811

It does seem to "focus" the air quite nicely but, as I said, I'm not sure how it compares with the "air assist" you've been playing with. It's probably less -- i.e. it doesn't clear out all the ash -- but that may be simply because it's not so tightly focused as the inflation needle provides. -- David

 

[wild.bill]

Good morning,

I never felt the need to enclose the laser so I never did.
My take on air is all I have been trying to do is move any smoke away from the area that I am cutting so none of the light reflects away and anything no matter how small that does the job is air assist. I have seen people use fish tank air pumps and they can do the job and a lot quieter than my air brush pump.

On my newest laser has a good size 40mm fan on top and it moves more air than my old one and keeps the smoke away which is why I have not been using anything else. You can see in the picture its the high volume fan. This laser has a separate TTL board which is next to my controller so it has 4 wires running to the laser module.