[pudrik]

Hi.

Ive recently purchased a 40W laser cutter engraver from china and ive found that this forum seem to have alot of people with experince in lasers of this kind so i have a couple of questions.

Since moshisoft is a really really crappy software i didnt learn in deep how it works other then i open my DXF in corel and save as PLT file. i later use the PLT option in moshi to load it before cutting / engraving. (mostly intrested in the cutting part)

Due to crappy service from DHL they cracked my tube so i had to order a second one and change it, calibration was a pain and if i may say so myself i dont think its that good at all. Tips on how to calibrate it better an easier other then removing mirrors put scotch tape and press "test" move a little bit and repeat? Is there some way to fire a low level visible laser for calibration?

How important is it to have a center center on the focal lens?

Ive accidently dropped the focal lens when removing it and im not sure what side should be turning up or down, golden up or green up ?

Ive tried to cut into 3mm acrylic the laser eats it like it was butter, but when it comes to cutting details it fails horribly either by making it look like a melted horror show or only carve it half ways. Speed / power settings?

Ive also noted that the cut isnt straight more a little stray causing the cut not to be perfect 180 degre (probably due to bad calibration from my end)?

When i try cutting 4mm plywood it looks like a massacer i have to use high power and slow runs multiple times and i stil dont manage to get all the way, ideas ?

im using the plastic piece that came with it to align focal length to around 40mm from the cutting surface.

all help/ideas would be appreciated

[Smiffy6885]

Hi, I'm looking at purchasing one of these from eBay too, iv done quite a bit of research to try and preempt any pit falls. Have a little google for cheap Chinese eBay lasers, there are a few blogs out there that really go into detail on the finer points of calibration and focal height, off hand I think the machine ends up working better at around 57mm, but please don't take my word for it.

Can I ask, what version of Moshi are you using and how are you finding it? I'm trying to decide between newlydraw/seal, moshi or laserdraw/WinsealXP, so any insight would be great.

Also, you might want to consider adding an air assist, this (as far as I understand it) will reduce/prevent the burning and melting when cutting thicker materials. And if yor feeling really brave you may want to have a look at making the crystal in the board swappable, this makes it possible to slow the cuts down manually by lowering the crystal hertz. From memory I think the moshi board comes with a 20. Haven't seen anyone speeding it up tho.

The off 180 cut is (again, as far as I understand it) due to the laser not be centrally alligned and not having the beam strike the lense dead centre. Also have you given all the mirrors and lense a good clean? This can really reduce the lasers effectiveness. As for which way up the lense goes, I'm not sure.

Hope that helps a little.

Steve

[pudrik]

well i got the latest version of moshi (9.92?)from their homepage ??-? as im running win7 and the one that came with the machine v9.2 didnt work (there is also a moshi 2012). Bad part is you cant boot it unless you have a dongle that comes with the software, been trying to remove it but the software has anti debug detection etc.. so its showing quite hard (only have 2 usb ports on my laptop so i want to clear on, no other reason for trying to remove the copy protection)

been thinking about adding a air assist but havent gotten around to it yet as ive i belive that somethings is really wrong in my config as i cant cut 4mm plywood with even 5 passes at maximum strenght (cutting problem first, cosmetics later) as ive seen on This week, I have been mostly working on… blog the cutting in plywood shouldnt be any problem on only 2-3 passes also gonna try his calibration tips. (and yeah also concluded as he did that the gantry is crappy and about a couple mm off in my assembly causing 1 corner to be WAY WAY off when everything else is totaly centered)

And about the crystal part, soldering shouldnt be any trouble as i mainly repair / refurbish electronics. got any link where youve got the info about the crystal on stepping?

havent tried cleaning the mirros yet but thats not a bad idea. i figgured the 180 alignment might probably be due to "incorrect" instructionvideo included as they adjust final center positioning by tilting the 45 degre mirror with some scotch tape.

my machine came with 0 manuals in paper form all included was a cd with software and 5 incomplete instructionvideos (last step look everything is good style) i bought it from a company called Dexian in china using aliexpress they have however been extremly helpful in determinating what was wrong with my machine on delivery and also on providing information about most of my questions. still waiting for my replacement tube from them (didnt want to wait so i ordered a spare one from another supplier)

Only tip i can give you is if your shipping by DHL or equalent demand that from your seller that you will buy the shipping and pay for it and a pickup will be arranged at their specified location (no dont let the seller do this for you as the direct paying part only have CLAIM if anything breaks during transport)

and almost forgot, my machine came with a normal acrylic glas in the "viewport" insane to say the least. I would recommend buying safety googles and never look directly at the laser. i THINK the co2 operate at 10600nm but im not sure.

[Smiffy6885]

Here that link:

Laser Cutter

The whole blog has some great stuff in it, the guy clearly has a good technical knowledge.

As for the dongle issue, have you though about a cheap hub hidden in the machines housing?

Thanks for the shipping advice, I think there must be a warehouse in Portsmouth full of these Chinese cutters, as all the ones on eBay seem to be from there.

I know youve only really used moshi but if you you had to make a recommendation, whichl driver would you pick, newly or the laserdraw/WinsealXP models? Or would you stick with moshi?

I've gotta say, if I do end up purchasing one of hese machines, I'll be swiftly checking, cleaning, lubing and rechecking all the mechanics before I make my first cut. I have read in several places that the mechanical alignment can be a bit off and loose.

P.s. just read a great artical on here about makeing your own mirrors from HardDrive disks. Might interest you if you want replacements for dirty or burt ones.

[pudrik]

hehe im kinda to lazy when it comes to the hub part, hence a small usb hub costs around 20$ around here and i dont wanna wait 2 weeks to get one from china

about the software i would say go for the cheapest, if you hate it and want to replace them youll end up with a stepper setup and probably mach 3 so cheapest = best if you ask me.

and yeah saw that post about the hdd laser mirrors on hackaday, one word AWESOME!

[Exsecratio]

acrylic glas in the "viewport" insane to say the least.

Acrylic has almost a 100% absorption rate for 1064nm radiation. Much safer than glass as well as far less likely to get broken.

The colour is to reduce glare, nothing more.

That said Laser goggles are a great idea

best wishes

Dave

[pudrik]

Update:
realigned mirrors once more, have good focal point on 3 corners of the gantry, gotta live with the bad settings until i have time to disassemble and modify it.

Also cleaned mirrors with alcolhol.(think this was a mayor player)

Can now cut 4mm plywood on 2 passes using about 50% power.

Not sure but seems like the glue in the plywood is vaporizing on cut and causing a glueish resedue to form on the optics causing enormous loss in effect when cutting, (first cuts works fine later ones not).

Gonna stock up on rubbing alcohol tomorrow to see if i can replicate the cutting efficency, if so i gotta connect a air assist and possibly a better air exaust to reduce the buildup of residue on the optics.

[Things]

That's 1 major downfall on the cheap lasers, the lack of air assist. It's not only there for assisting with the cutting, but to keep the gunk away from the lens.

The second the vapourized particles land on the lens, the laser begins basically baking them onto the lens. You can only clean it so many times and so much before the lens is basically ruined. I'd highly recommend adding some form of air assist, even if it's just strapping a fan on the cutting head.

[pudrik]

My idea is to connect either a aquarium pump to push away debree, or modify a compressor for suction / both might also be an option

And a lasersight to easier show where the cut is gonna be made.

[fishface]

Hi.
Did you ever get this working to your satisfaction?
I am in a similar situation; I've just bought a cheap and cheerful Chinese laser. My problem is that I can only cut about 1mm into acrylic sheet even on full power. I've tried aligning the mirrors by using a low power test fire at thermal paper in front of each one, and cleaning them and the lens with isopropyl alcohol. There is nothing visibly wrong with the tube and water is circulating correctly without any air locks.
I have a slight dark spot on one mirror which won't clean off even with alcohol; could/would this be causing such a large loss of power?

[herby08]

Hi there
yes all the mirrors have to be pretty much surgigal clean.
you need to replace them you can go for a free mirror cut out of a old harddrive disc they are even better then the gold mirrors and are free.
just cut tem out with a hole saw in the size you need.
greetings
walt

Hi.
Did you ever get this working to your satisfaction?
I am in a similar situation; I've just bought a cheap and cheerful Chinese laser. My problem is that I can only cut about 1mm into acrylic sheet even on full power. I've tried aligning the mirrors by using a low power test fire at thermal paper in front of each one, and cleaning them and the lens with isopropyl alcohol. There is nothing visibly wrong with the tube and water is circulating correctly without any air locks.
I have a slight dark spot on one mirror which won't clean off even with alcohol; could/would this be causing such a large loss of power?

[fishface]

Thanks for the advice; I've replaced my black spotted mirror with a piece of harddrive platter and hey-presto; I can now cut 3mm acrylic in a single pass. Still need to align a little better and sort out my speed settings, but this is enormously better than before.
Now to throw away the electronics and get LinuxCNC involved......

[pudrik]

Fisheye:

Frankly i havent had the time to try to finetune my machine recently, alot of work and no play

I know that cutting 5mm MDF or 4mm Plywood should be any problem as it manges to cut it with surgical percition when i push the "test button" and move the piece by hand (not a nice cut but proved the point)

Im getting kinda feed up with mushisofts ****ty software.

Ive planing to install a better air assist on the nozzle as this seem to be ALOT of the issues, and ive changed the waterpump to an external PC water cooling system. As for the software im quite unsure as of yet might even concider if ive get enouth time to write a better software.

The USB A port connector has been replaced by a cheap USB hub that leeches power from the internal PSU board, Security dongle has been fitted on the inside and the connector to the PC is now USB type B

Not sure what todo about my crappy missaligned gantry, might adjust the axis hole or simply scrap the current one and build a second cutter from scratch, lucky for me ive got a spare tube to experiment on. (yeah i know lazarus is out there but it costs more then a commercial one)