Tweakie published a new build:

Read more about this build...

 

I haven't even got to the complicated bit yet, but yes I agree this is not for everybody although there has got to be some other wacko's, like me, out there somewhere.



Tweakie.

 

Hi Mark,

Yes indeed sir, the total distance the beam has to travel does affect the power.

In practical terms a variation in distance of 4’ or so will not produce any noticeable variation in power but if this distance is increased to say 8’ then it may start to show. For this reason the larger commercial machines (bed size 8’ x 4’) actually mount the laser tube ontop of the gantry so it travels with the Y axis then the beam distance variation is back to within the 4’ or so.

I have no way of actually measuring my laser power at it’s smallest focussed point but, just as a guess, I would suspect it to be approaching a kilowatt.

Things you can cut with a laser will depend on the laser beam’s wavelength.

Just as an example the beam from a ‘visible beam’ laser will travel straight through clear Perspex, glass etc. whereas an Infrared laser (not visible) of the same wattage will cut into Perspex and etch the surface of glass.

The cool looking tube was manufactured in the USA. Unfortunately, when it eventually reached the end of it’s useful life, it could not be replaced with like so I had to turn to a China manufactured tube instead – still looks cool though.


Tweakie.

 

I have never actually seen a 40kW laser but I don’t think it would even go in through the door of my workshop. Perhaps best if I keep to 40Watts.

Tweakie.

 

Thanks Michael,
Very valid points that you have mentioned, I think most of them will be covered as the build progresses but I just haven't had time to write it all up yet. Stay tuned folks

Tweakie.

 

Tweakie.

 

Chicken's egg shells

Tweakie.

 

Thanks Mark.

Tweakie.

 

Perhaps one of the greatest advantage in adding a CO2 laser is it’s ability to cut acrylic.


Acrylic is one of those materials which will easily sublimate (change state from a solid to a gas without going through the liquid stage) and as a bonus, it also has the property to act as a waveguide at the 10.6 um wavelength of the laser beam. This enables acrylic up to 10mm thick to be cut with reasonably straight sides and have near perfectly polished edges which require no additional finishing.


This Open Builds Logo keyfob took just 45 seconds to cut from 6mm Plexiglas and was made, just as an example, to illustrate laser cut acrylic.


Tweakie.

 

Laser beams do not actually contain any heat, they are just a coherent stream of photons. It is the reaction of the molecules in the material laser beams come into contact with that generates the heat.

Tweakie.

 

These little bikes were laser cut some time ago and they are perhaps a good example of the edge finish that can be expected when working with acrylic. Unfortunately not all plastics behave the same way - with Polycarbonate, for example, it is doable but the edge finish is extremely poor in comparison.


Exactly what a laser can and cannot do is to a large extent determined by its operating wavelength – for example my 40 Watt CO2 laser (operating a 10.6 um) will find almost all metals to be excellent reflectors, the laser beam just bounces off leaving the surface totally untouched. With different types of laser (YAG / Fibre etc.) operating at far shorter wavelengths the situation is entirely different and almost all metals are easily etched. So it is basically ‘horses for courses’ and a bit of trial and error soon reveals the strong and the weak points of any particular type of laser.


Tweakie.

 

Hi Manuel,

Welcome to the forum, its very nice to see another CO2 laser user here.

Tweakie.

 

Two of the best – without them we would not have the V-Slot and our tremendously popular forum of builders and inventors that just keeps growing and growing.


Thanks Mark & Trish.


Tweakie.

 

A short video demonstrating PWM control of laser output power enabling seamless engraving and cutting operations using Mach4 with the Darwin driver and of course my homebuilt machine.

http://www.graytel.talktalk.net/Darwin 2.wmv

Tweakie.

 

Maybe, one day I will give it a try.

Tweakie.