Blackhole 60W Laser

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Re: Blackhole 60W Laser

Postby iGull » Thu Nov 10, 2011 10:48 pm

Hi All

It's been a while since I last updated the log - mainly due to vacation and general laziness :D

Things have moved on a little since my last post, I've installed some electronics, air and waterworks to get the beast moving (most of the work is temporary, but the stage and X axis cabling is permanent).

I'm now running with a pair of Keling 4020 drivers at present along with a Lasersaur setup consisting of an Arduino Uno (with lasaurgrbl) interfaced to my Macbook Pro running the python serial server and a copy of Firefox (the serial server I believe is to be moved from the host computer to an Mbed ). What can I say, everything I have touched with arduino and lasersaur has worked first time every time - no glitches, no hang ups no reboots - zilch - it just works. Anyone that puts down this arduino setup needs their heads examined. OK, it may (in the future) have some issues with rastering, but the current setup works faultlessly and is a VERY clean interface (Mach take note :lol: ). It won't take much to turn this setup into something very professional (and also CHEAP !). I should really join the lasersaur set, but I only need the software (and I can spend sixty bucks on the skins :D ), so there's not much point - I'll wait until it is fully open source.

Really didn't have any issues installing and aligning the 60W tube - apart from the fact that the original tube I received was broken (the water nozzles at the rear were snapped off) and the new replacement tube I find is NOT 56mm but 60mm in diameter !! Consequently, the tube doesn't fit my mounts :x I haven't informed coletech yet - the tube is 1250 mm long, so it's not an 80W tube (which is what I thought - it does say in chinese if anyone can read it). However, I lashed up a couple of alloy tubes and epoxied the rear nozzles back to the original tube - bingo, no leaks and it all works - AND I have a spare tube - albeit 60mm :D I may be prepared to sell the new 60W tube if anyone is really interested - I believe there is a shelf life.

Had a few semi-major design issues - my original intention was to have a 1240x620mm working area, but due to a faux pas, the energy chain interferes with one of the rear Z mount brackets and loses me 18mm of Y movement - I can still cut 1210x610 (4'x2') sheets 'though - just :roll:

The new Z belt system works fine and is quiet - however, I haven't had the chance to do anything with it yet and just rotate the whole thing by hand for now :D While on vacation in Florida, I was directed to this surplus 'shop' - Skycraft Surplus (more of a warehouse - even has spares for cruise missiles :D ) and scored a proximity sensor for 5 dollars - best part of 70 GBP across here so it was worth the ten minute drive. I have it mounted and it works (within about 5% each time) - I have a small 15mm disc of alloy that will sit on the material - the intention is to build a small utility processor with a stepper driver that can handle all the odd jobs needed. Saying that, a winder handle on the z axis leadscrew and an 11mm gauge works equally well :D

I've attached a couple of vids of the beast working - I still get a kick out of laser cutting balsa ribs - when I consider the amount of wasted time in my life cutting ribs with a broken razor blade :lol:



Next are the skins - my original choice was magnet fittings, but after getting some sample skin material, the magnets came undone - epoxy/cyano/gorilla/silicon - the magnets eventually pop off the rear painted surface - I'm really annoyed - I've moved to screws under duress, but at least they are into small tabs that will fit in the extrusion slots. The removable panels will have thumbscrews. I guess this machine is really a prototype and you have to put up with some compromises, but that's not in my nature :lol: :lol:

Once the plenum floor is fitted (there's a second floor to be fitted above the waterworks and electronics to form a 'smoke' plenum) and the eggcrate table is done, I need to make some decisions about which controller system I will finally use. Tim Wehr has just posted some info on his blog about tests he has done using VMware Fusion on his Mac using the LO Controller - this looks exceedingly promising - anyone need a cheap(ish) 60W tube in the UK to pay for it =;-???

Cheers

Neil
EMOs are a sign of weakness ...
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Re: Blackhole 60W Laser

Postby iGull » Mon Nov 14, 2011 9:20 pm

We have liftoff :D

tintin.JPG
Tintin rocket from Thigiverse


Don't know what's going wrong with the pic, it's portrait on my computer - rotated it and it's just the same !

Spent some time at the weekend testing a pile of materials - lots of success, but many failures ! I had hoped with a 60W laser that it would be able to cleanly cut 6.0mm birch ply - not. This is good quality 'aircraft' 7 ply - not the cheap and nasty 3 ply you get from DIY stores (although I had the same issue with that too :cry: ). I barely made a dent in it - perhaps 3mm if I'm lucky - full power and only a couple of hundred mm/min - lots of black soot though :D

It would have been nice to check a database of materials and their cutting speeds/powers required. I fully realise that each machine is different, but there has to be correlation somewhere. I'll create my own as a matter of course as it'll be needed anyway. I don't see a 'database' of materials in LaserCAD or PHCad - I should have thought that it would be a necessity ??? My step-four cnc router software had all that built-in - feeds/speeds/materials.
If there is any interest in a database, I could lash something up in FileMaker (I can create standalone databases for a couple of platforms) - maybe an online wiki would be more useful 'though - Bart?

However, scored a brace of transparent yellow 6mm perspex sheets originally intended for an optical cleanroom area - makes for a nice transparent cover for the cutter!

I did a full cut of a tintin rocket (thingiverse) from 3mm liteply - cuts very easily on low power - so I'm quite happy with the results. Beam diameter seems to be a tad under 0.23mm - this is with a 63.5mm lens - I'm really not sure what it should be - 50mm lenses seem to be around 0.15mm ??? Perhaps someone can clarify. I've done a focus ramp test and the focus range is quite wide - about +/- 2mm.

I also picked up some old free plastic lighting grid - actually works ok - after loads of cutting, it's barely cut away - it'll do for now.

Cut some 20x40mm extrusion end caps from 6mm smoky acrylic - really fast to cut - but the smell - yukk :D I don't have my extraction fitted yet as there are no skins on. You can't get 20x40 caps for bosch/rexroth - you are supposed to use 2 20x20 caps. I just screwed them on using core screws.
I've cut my hand a few times on the bare extrusion, so they are quite useful.

Cheers

Neil
EMOs are a sign of weakness ...
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Re: Blackhole 60W Laser

Postby TLHarrell » Tue Nov 15, 2011 12:40 am

Sweet little rocket. Looks a bit like the lamp I designed.

Image

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Re: Blackhole 60W Laser

Postby mikegrundvig » Tue Nov 15, 2011 4:13 pm

Ugh, I'm really disappointed to hear you can't cut 6mm plywood with a 60 watt laser. Obviously the glue used is critical but still, I'd hoped that 20 extra watts would make a difference. A friend of mine says the FabLab-type place he goes to routinely cuts .25" plywood on a 50 watt laser so I'm just not sure why they can do that and a 60 watt is having trouble. Do you know you are getting the power you expect? Is the tube old and partially discharged? I really need to cut 0.25" plywood a lot so this is making me think I should go with at least an 80 watt tube. Thanks and good luck!

-Mike
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Re: Blackhole 60W Laser

Postby twehr » Tue Nov 15, 2011 4:32 pm

mikegrundvig wrote:Ugh, I'm really disappointed to hear you can't cut 6mm plywood with a 60 watt laser. Obviously the glue used is critical but still, I'd hoped that 20 extra watts would make a difference. A friend of mine says the FabLab-type place he goes to routinely cuts .25" plywood on a 50 watt laser so I'm just not sure why they can do that and a 60 watt is having trouble. Do you know you are getting the power you expect? Is the tube old and partially discharged? I really need to cut 0.25" plywood a lot so this is making me think I should go with at least an 80 watt tube. Thanks and good luck!

-Mike


It's all in the glue.

I am cutting 1/4" red oak and birch ply from the big box stores with 40 watts - slow but cuts in a single pass.
tim
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Re: Blackhole 60W Laser

Postby iGull » Tue Nov 15, 2011 9:49 pm

Hi All

First off - nice rocket lamp ! Reminds me of Buck Rogers ! BTW, how DO you get the bulb in :?

mikegrundvig wrote:Ugh, I'm really disappointed to hear you can't cut 6mm plywood with a 60 watt laser. Obviously the glue used is critical but still, I'd hoped that 20 extra watts would make a difference. A friend of mine says the FabLab-type place he goes to routinely cuts .25" plywood on a 50 watt laser so I'm just not sure why they can do that and a 60 watt is having trouble.


Mmm - what we need is a level playing field here - something common we can all refer to worldwide - I'm guessing 3mm liteply (laserply as it's occasionally called) - most ARTF model aircraft/boats/castles are made with it - might be an answer ? Other option might be a notepad of graphpaper ? Although I can get access to a laser power meter, from memory, it only went up to 10W at 10.6um - anyway, even between power meters there are huge differences ! (I had problems through my whole working career with calibration pi$$ing contests :D )

mikegrundvig wrote: Do you know you are getting the power you expect? Is the tube old and partially discharged? I really need to cut 0.25" plywood a lot so this is making me think I should go with at least an 80 watt tube. Thanks and good luck!


The tube is brand new from Coletech - however, I have no idea of it's condition and age - label says something in chinese the 11/07/11 which I'm assuming is the 11 July 2011. I'd really like to cut 1/4" plywood too :D which is why I went to 60W ! My experience of laser cutters is low, perhaps the 50W laser your friend has access to is an expensive RF type and not an 'el cheapo' chinese tube like mine ?

twehr wrote:It's all in the glue.
I am cutting 1/4" red oak and birch ply from the big box stores with 40 watts - slow but cuts in a single pass.


Define 'slow' ? Therein lies the rub Tim - expensive plys tend to use phenolic resins - phenol-formaldehydes from memory - also used to manufacture printed circuit board (before epoxy glass fibre) - that might account for not cutting through my aircraft ply (it was 6mm 5 ply BTW, I just checked).
I don't know how many laminations would be in your ply Tim - I'm guessing 3 ? I know the US home trade uses different timbers to Europe, so trying to get a worldwide handle from there could be difficult.
As a quick test, on full power at 600mm/min (10mm/s), I can cleanly cut through a stack of 4 sheets of 3mm liteply at once.

I've done some quick testing - the fastest I can make a clean cut of a 20mm square of 3mm liteply is 2500mm/min - 41.6mm/s - 98.4"/min - 1.64"/s.
I also did some tests on a paper graphpad lying on my desk - it's 5mm graphpaper - sheets are 0.07mm (0.003") thick - here's the results ...

0.76mm @2500mm/min (98.4"/min)
0.99 @ 2000mm/min (78.74"/min)
1.35mm @ 1500mm/min (59.06"/min)
1.75mm @ 1000mm/min (39.37"/min)
I didn't count the sheets, being an engineer, I used a digital vernier gauge - I left it to the student to calculate how many sheets it cut :D

I'm hoping someone can perhaps try a similar test with their 40W chinese tube lasers. I revisited my laser alignment at the weekend and I'm extremely happy with the alignment - everything is down the centre. I double checked the beam placement from the final mirror by aligning the tube to a scribed circle with a cross (mine is the big coletech black assembly BTW) - the tube was moved back up to focus position, the spot was smack bang on the crosshair. FWIW, from the bottom of my nozzle to the cuttable surface is 11mm (I have a 63.5mm lens). I fully cleaned the optics with methanol before I tested tonight.

Something I also did as I had previously seen 'stitching' in my cuts (probably due to using the lasersaur board - I'm guessing the PRF of the PWM signal is a bit slow) was to use the 'test' button to ensure it was at max power (no other connections connected to the PSU other than 240V) - judiciously pressing the button at the start of the cuts :D

Apologies for the long post, I look forward to any replies and suggestions.

Best regards from a wet and windy Scotland

Neil
EMOs are a sign of weakness ...
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Re: Blackhole 60W Laser

Postby TLHarrell » Tue Nov 15, 2011 10:47 pm

iGull wrote:First off - nice rocket lamp ! Reminds me of Buck Rogers ! BTW, how DO you get the bulb in :?


Thank you. I'm really happy with it too.
There's a double ring just above the bulb socket. The two rings have three rectangular holes in them that have matching clips that lock them together.

Next up, I'm working on designing some permanent fastening methods for flat MDF parts so I can ship flat packed and don't require any glue.
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Re: Blackhole 60W Laser

Postby iGull » Wed Nov 16, 2011 2:33 pm

The sweet smell of success (or burning 6mm ply in my case :D ).

I took some time this morning to monitor the tube current on full power using the lasersaur board - 12.3mA. This is roughly half what it should be. The quoted operating current for a 60W tube is 22mA. Using the test button with a 5k pot set to max gave 27.2mA!

The lasersaur board setup uses only three wires - gnd(4), TTL-H(1) and protect(3). I checked the PWM signal on max (255) - straight lined at 5V as hoped. At about half - 128 - the PW was about 50% - PRF was 30uS. I added a pot to the setup and set to max - 27mA - backed it off until it was 22mA during a test cut (pot across 6,5 and 4 - wiper to 5).

I can now cut hard 12mm (1/2") balsa at 1100mm/min (18.3mm/s) on max pwr - I couldn't cut it at all before without creating a flaming mass :o
The 6mm quality aircraft ply (5ply) - I can just cut it at 200mm/min - but to be honest, the material is really cremated. I tried two passes - lowering the nozzle half way - but that was just as bad - as Tim said, "it's all in the glue" :D

I'm not sure why it is is happening now, but I can cleanly cut 3mm liteply at 4000mm/min (157mm/s) - and the edges are barely marked.

Anyway, I'm happy today - I need to re-read the chinese manual that comes with the PSU (coletech) - looks like you set the max pwr attainable with a pot (current limit) and the PWM gives a percentage of that max. No pot, and it would sem the current is limited internally to about half. I also need to look at Barts schematic - as they say, if all else fails RTFM :D :D

I'd like to hear anyone's attempts at MDF (not chipboard) - I get VERY blackened edges on the stuff, it's not pretty - I can cut up to 9mm (albeit at 300mm/min).

Cheers

Neil
EMOs are a sign of weakness ...
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Re: Blackhole 60W Laser

Postby TLHarrell » Wed Nov 16, 2011 4:45 pm

MDF cuts great on my little laser! It's very homogenous, so cuts are always the same. I usually use 1/8". Edges do come out quite dark. I have also cut 1/4" MDF, but it requires higher power and more passes, and has significant charring. Pieces still come out with very tight tolerances though. I can maintain a tight slip fit on slots by offsetting the original part by .003" and cutting normally.

Rastering produces zero char. Vector cutting, even at very low power for marking (see rocket above), does produce dark lines. The hatching on the fins was rastered, the remaining details were vector cut at 2% power.
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Re: Blackhole 60W Laser

Postby mikegrundvig » Wed Nov 16, 2011 8:55 pm

I'm very glad to hear it's working great. I'm going to take a partial assit on this one with my comment " Do you know you are getting the power you expect?" :)

-Mike
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