A proper CNC machine

I have always wanted to buy a CNC machine to cut cases like Frank does, maybe build some prototypes. So far the CNCs that stand out are the Probotix Fireball V90 and the Rockler Shark. Does anyone have any recommendations for cutting acrylic and aluminum accurately?

For cutting acryl use a laser. With a CNC Machine you will never be able to cut sharp 90°corners hence to the diameter of the milling cutter. The V-90 is a toy (albeit one of the better ones) compared to a CNC thats intended to work 24/7 and is with some proper options 1700$ (they only cleverly stat the BasePrice :wink: ) The Rockler Shark doesnt look any more rugged and is even more expensive. My tip would be looking for a used “Pro” machine maybe even from a specialized machine dealer. That won’t be more expensive and will be better investment even when heavily used.

@fcd72 whoa, awesome advice. The Pro is not a laser cutter right? Do they make a laser attachment?

There are indeed Laser System from EuroLaser that can do both, but these are mainly LaserCutting Machines rather than Milling machines. Keep in Mind that a Laser is principally the same (a x,y,z Plotter) but the Lasers mechanic is much lighter as it only has to move a mirror rather than a bulky 1kW Electric Motor. The Laser itself is mounted somewhere to the Base of the machine as it would not withstand the vibrations on the Motion System for long (its always a Gas Laser so it has some kind of Tube made of Glass…) and would be even heavier than a Motor (we are talking in the 15-20kg class without coolingI.

A used refurbished Pro Laser System for Cutting Plexi (with at least 30W) is around 5000€ over here, keep in mind that this is only the Laser, you’ll need some infrastructure (extraction, purge, a PC, Software) to make use of it.

I found this one here in the states. The price seems very good for a 40w.


Frank will tell you more on that, but a laser cutter at this price should be pretty much considered a DIY project rather than a ready to use solution. You’ll need to tweak it and calibrate it a lot if you want it to work reliably enough to do something like a Shruthi-1 case.

The clue is in the name “hobby” I guess. But it is still better than doing it with a hacksaw :slight_smile:

You’re much better off making cases from wood if you’re a hobbyist I think.

The thing from fslaser looks a bit like a Toy… and if you add some options (Air, Extraction, a 2.5" Lens) hit quickly adds up to 5000€. For a machine i wouldn’t invest in if i wanted for my business. The Head Assembly tells it all…this machine won’t make some hundred hrs before wearing out every single roll. Worn Roll means 15 Minutes for replacement and a whole day of calibration. Don’t be fooled, they all work fine on Videos/Demos, but the crucial thing is, will they do this hour after hour, week after week? You are paying a lot for the more or less invisible Quality. Ive got good reasons for this:

  • The Head assembly from your mentioned Machine has only 3 Rolls, all in one Plane and a massive Aluminium Plate carrying even the pointer laser (BTW you will have to adjust this thingie to the different Lens Focus…) so a massive Torque is on the Rolls. They will wear in hours so your beam will be tilted in y Axis and be out of Focus. Pro Machines have the Red Beam Pointer Laser coupled within the Cutting Lasers Optical Path with a semitransparent Mirror.
  • Speaking of Focus - This thing seems to have no AutoFocus (a Z-Axis Probe) - so prepare for prolonged Focusing Sessions burning precious material.
  • Id like to see the other Mirror Assemblies, its important that these Mirrors stay always in place, not easy when mounted on a moving bridge, accelerated the whole day with some Gs…
  • The Y Axis in this machine looks like simple round Rods, that are suboptimal in terms of precision but cheap - the bearings look like cheap plain Teflon Bearings.
  • They don’t tell what Servos they use, there are huge differences in available Accelerations / Lifespan (on my first machine the Servos now have 4700hrs are still superb and a replacement set costs about 900€).
  • They state this machine has a 40W Laser, which Brand is it ? (preferably Coherent or Synrad… the rest is - ähem - questionable?). Why do they state 40W and tell you later its “Peak” and there will be 30W-35W average? Is this some kind of tolerance which would mean the Manufacturer isn’t able to build precisely one Tube like the other? Trustworthy Vendors tell you how much Power they put on the Cutting Table available for cutting, not what the Tube “Peaks” whatever that will be (LaserTubes are regulated by PWM, if you want to lower power you will have to switch it off and on, so theres no “Peak”)
  • They don’t tell a thing about the Lifespan of the LaserTube. I have seen vendors that claim 8000hrs (which sounds like a lot…) but its a sealed Glass Tube and the 8000hrs start after sealing it off - so the Tube will last only 10 Months after being produced! The Laser Tubes in my Machine are guaranteed for 15000+ hrs of nominal Power Output and cost more than that whole System.
  • What Brand/Quality are the Optics. I have seen coatings from Lenses falling apart after a Week rendering the Lens useless, pretty bad for a 250$ Lens. If the Mirror isn’t plane (and plane means 1 Atom!) you will loose significant amount of Power and the Mirror gets hot so your Beam will run out of Focus…
  • There is no Vacuum table to extract the produced Fumes to the bottom.
  • It has Water Cooling - so the Water runs thru the Glass Tube and thru your machine. You will need a Pump and a Reservoir or a Cooler. If your Cooling fails the Tube will die within Minutes if you don’t notice. Coherent and Synrad manage to build Laser with up to 90W Aircooled that automatically switch off when cooling fails for any reason. Personally i would not buy a water cooled system.
  • They Charge 250$ for a Phone Support of a 5000$ System??? Over here this is for free.

Don’t get me wrong, you shurely can have loads of fun with this machine and produce fine cases/whatever with it. But i don’t think it would stand my Use for more than half a year without anything breaking and id curse it everyday for the time id have to put in in for calibration. A Laser Cutter is a moving precision Optics System with at least 2 Moving Mirrors (most have additional 1-2 fixed) and a Moving Lens, all this vibrating and in a dusty environment - it takes quality and experience to keep this running. I have now 3 Mechanically Similar Machines (with different power Tubes) and after 6 Years of professional Laser Cutting i still call the Service for some Problems and see still Problems that are new to the Service.

If you want something to Play try this: http://www.ebay.de/itm/40W-CO2-Graviermaschine-Lasergraviermaschne-CE-Freien-Waben-Bett-Laser-Engraver-/130729844623?pt=LH_DefaultDomain_77&hash=item1e701b1f8f#ht_3340wt_1263

Its a bit cheaper, but be aware it has one of these Cheapo 800hrs Tubes that will die within a year…

@fcd72 I’m really only looking for light use to test prototypes. Any large jobs I could send the files to you. Sound good? No reason to tie up your time making prototypes when I can send you a bulk order.

The “peak” probably refers to what the tube can handle for very short amounts of time… Typically used later as an excuse by the manufacturer if the customer claims that the tube didn’t deliver 40W consistently, or the tube breaks before the mandatory 2year warranty has expired.

Safety is also a problem (at least for me) on the cheap Chinese machines… :frowning:

I wonder why you couldn’t simply “cut past” the corner on a regular CNC to get exact corners ?

A Laser is “digital”, there is only ON or OFF, so there can’t be a Peak when you raise the voltage a bit… If the Tube can’t be powered on 100% of the time its Crap anyways.

before spending 5k+ on a machine you only occasionally use… you can as well print the Proto and cut it with a knife from Cardboard. I don’t know how many different Protos you plan but this may save you 5 Grand minus a Propper cutter :wink:

@fcd72 that sounds like a good idea. :slight_smile:

Yes, you can however send more power to the laser (via the driver), thereby increasing power and reducing lifespan considerably…
( I wouldn’t expect their technical documentation to be correct and/or complete for that price anyways ;D )

You can’t dim a Laser. Its either emitting a Laser Beam or not, you can only Pulse it to have averaged over time less than the Maximum Stable Emission. The Power emitted is determined by the amount of Medium and the Physical aspects of the Resonator(how much Light is coupled out). These are physical Parameters you can’t change by the Driver hence they are built in :wink: If the Laser isn’t capable of continous emitting nominal Power (it must be switched off due to possible overheating or damaging the resonators or whatever) its fairly useless. Its a bit different from your Car, there is no wear to the Medium, the Lifespan is determined by foreign non Medium Molecules that diffuse into it. And even at your Car you expect it to deliver full power for prolonged time (say minutes of Full Speed on the good ole german Autobahn™ ) without breaking apart and not only a Peak…

Hmm… Must have forgotten my brain somewhere, I duly apologize ! :slight_smile:
I only deal with solid state lasers, not switched ones, so I forgot that high powered lasers are switched :slight_smile:

Nicht schlagen meister fcd72, nicht schlagen :smiley:

Nice car analogy by the way :wink:

heh, all this laser talk: Here is my toy at work

WTF is this?? Looks like a Laser originally for Msdical Use?

Welding laser. Mostly stainless steels. 10watt water cooled, needs 2 phase power. We use 600 and 800 um delivery fibers. Throws a 5" plasma plume with each shot :slight_smile:

10w per pulse i assume?

Ya max, we use about 6 J for normal welds. You can take a needle, break it in half weld it back together :stuck_out_tongue: we use a step index fiber though so is no good for cutting