DIY Laser Cutter Project

[HIMNL9]

Re: My holiday project

PWM (pulse width modulation) control allow you to turn the unit on and off very quickly, changing the duty-cycle (or, if you prefer, the proportion between the on and off time) of the driving square wave.

So, if you drive it, say, 10KHz, with a duty-cycle of 10% on (laser turned on for 10% of the time and off for the 90% of the time), you get the 10% of the power, if you use a 50% duty cycle, you get the 50% of the power, and so on.

 

[methuso]

Re: My holiday project

ok i get the pulse width modulation but how do i connect it to my computer to do this ? I have used ttl on one pin for a diode that i kept burning up. so i guess that i can connect one of the TTL-ports on the PSU there and Ground to common ground but how do i connect for the PWM? directly to another free pin or do i need some PWM-hardware?
BTW.. Im using Ubuntu/EMC2

 

[HIMNL9]

Re: My holiday project

Ehm, you will need a PWM hardware, or a program for drive an output (like one line of the printer port) with the PWM signal generated from the program ..... or also a program that drive your PC output on and off, and an external PWM oscillator for set the power manually ..... all depend from the use you need it.

Don't try to connect directly your PC ports to an external hardware without an interface (optoinsulated is better), otherwise you will risk to burn also the PC

 

[methuso]

Re: My holiday project

hm ok. thanks.
well i have the cnc-cards connected to a breakoutboard. dont know if its opto coupled or not.
Ill have to investigate this further before powerup

/Ulf

 

[Things]

Re: My holiday project

I have been told that Mach3 is not all that good for PWM output, and that you'd probably need a specialized control card for it to work properly (Not the cheap Chinese CNC boards).

The PWM input is taken in by the CO2 laser power supply, where it passes through a filter to smooth out the pulses. The smoothed power is them proportional to the PWM level, which is then used to control the laser tube. It doesn't actually turn the laser on and off to achieve different powers, as the peak power would still be the same, and you'd just burn lots of little holes into whatever you're trying to cut/engrave.

I'm not sure in the exact details, but I believe what you can do is connect the laser PWM input to the step pin of an unused axis, then set Mach3 to use that as the spindle motor.

I will probably just have manual power control for now.

Progress has slowed again due to alignment issues. Alignment is proving to be a very, very tedious process.

 

[methuso]

Re: My holiday project

Thanks. Ill look into this. I'm usin EMC2 so there more difficulties to fight off too.. but i'm in no hurry.

/Ulf

 

[Things]

Re: My holiday project

I haven't really done much of an update on this project for a while. I've been pretty busy with school, and money isn't a strong point at the moment.

Anyway. I have made some pretty drastic changes to my machine. Infact, I have pretty much scrapped the previous version.

Mainly due to complicated alignment. If the machine isn't stable, alignment isn't gonna work, so I ultimately decided it needed a frame. I also ditched the v-groove bearing system and went with a much more stable rail system.

Don't get me wrong, v-groove bearings can be made to work brilliantly, however it worked out cheaper for me to do it this way in the end.

Anyway, it's going to be a bit slow on this one too (Money, once again). Also, if anyone has/has access to a CNC mill that can do some fairly hefty alu plate (say 12mm), I'd love to know

I have so far created the frame (20mm steel RHS), all welded up and ready for components.

Testing out the rail system:

The frame mockup:

The finished frame:

Like I said, those dual mounts on the end of the 2 Y axis rails I had to make by hand, but I really need to get them made properly before I can do much more with the carriage system.

Cheers,
Dan

 

[Things]

Re: My holiday project

Just did a bit more work on it, mounted the linear rods down. I've also found someone to make my dual mounts for me

Cheers,
Dan

 

[Things]

Re: My holiday project

I'd say this is a pretty good way of testing strength

I'm installing the 2nd platform that the CO2 laser will sit on.

Cheers,
Dan

 

[millirad]

Re: My holiday project

Crikey! That's coming along very nicely. op: kudos!

 

[HIMNL9]

Re: My holiday project

Are you planning to use this as high-speed machine ?

If no, then you probably may never have problems, with structural vibrations, if yes, i suggest you to add some diagonal extra bars, where you can do that ..... it will give you a super stable structure.

Also, if you plan to use it at high speed, probably doubling the carriage rollers can help too :beer:

 

[Things]

Re: My holiday project

OK, I have set myself a goal to have this cutter at least running, if not completed, by the end of the year! Hopefully with this little extra money from the laser harp kits, I'll finally be able to complete this.

That said, if anyone is able to do a little CNC machining work on Aluminium for me, please let me know

Cheers,
Dan

 

[Things]

Re: My holiday project

Just purchased a new ZnSe lens with a longer focal length, as well as an adjustable mount for it and some gold plated mirrors. Along with that I also bought some extra linear bearings to make it all a bit stronger, as well as some 10mm rod mounts.

I've also got permission to use the CNC machine at school, so I'll hopefully be able to make up a fair few parts before I finish school at the end of the year

So, if anyone needs a ZnSe lens with a focal length of about 1", let me know

Cheers,
Dan

 

[LaZeRz]

Re: My holiday project

After seeing your laserharp, im pretty sure that this is going to be epic once completed

 

[Things]

Re: My holiday project - DIY Laser Cutter

Thanks

I'm looking forward to when this is done. I've got a friend in Adelaide that has a great use for laser cut objects, I'd be happy to do jobs for people for a small bit of change (Although shipping outside of Aus would probably cost more than the job)

Mucked around with the belt system a bit today

Cheers,
Dan

 

[Things]

Re: My holiday project - DIY Laser Cutter

Update video



Cheers,
Dan