Need Help!- Fitting laser into homemade CNC

[marting]

Hi to all,
After having built my own CNC router a couple of years ago as most guys on this forum, I'm now considering to fit in a laser onto it to cut 5 to 6 mm thick perspex or wood. To be honest I'm not much bothered about how to fit it in or hook it up, but the big question is from where to start and what to look for. I've been spinning around on many forums of all aspects related to cutting with lasers on CNC but the more I read the more dishearthed i get due so many varieties.

Since I use this for hobby my budget is limited and was considering using a Co2 laser as this shown here 2pcs 100W co2 laser tube with power supply water cool - eBay (item 140493974710 end time Jan-23-11 18:21:39 PST) which looks decent but am relutant of using it due to the fact that quite fragile and so would prefare something solid like this High Power Laser Module -- 750 mw -- Cutting Burning - eBay (item 170589331533 end time Jan-13-11 12:19:02 PST) but am not quite sure this will do the job.

Having said this, it's obvious that my main difficulty to start off with is that I have no idea what sort of power range I require, too little will not float, too large a power would be an expensive overkill! I'm not interested in cutting metal, stone or what ever, just 5 or 6mm perspex and wood. Anyone could shed some light on this matter.

To give an idea of my machine and software here is the info:
Working area: 750mm (X) x 550mm (Y) x 220mm (Z)
Servo motor driven
Servo drivers from Rutex
Software: Mach3, OneCNC, Aspire and photo VCarve
OS: Windows XP
PC: P4 core II 2
Cheers

[zax15uk]

Based on your requirements I would go with an 80W CO2 tube, the diode option won't cut it

So you'll need the tube, psu, focus lens, a couple of mirrors and a water pump (ok, so there's some other small items but that's the basics).

That ebay link is expensive, I know it's for 2.... why? but it's still more than I would pay. Just contact a few of the Chinese sellers that are on here, several have good reputations for adequate packing and prompt shipping. I would expect under $800 shipped for all the items you need.

Zax.

[marting]

Hi Zax,
Thanks for the reply, I thought I'd have to recur to a CO2 laser! so now I have to figure out how to go around with fitting it in a manner that I can easily replace with my router when required, as I would still be needing it when cutting at depths more than 6mm as well as when doing reliefs. I have never physically seen such lasers but the ones I found on ebay are far too long (1600mm) to fit into my headroom which is about 350mm, while on the other hand I couldn't find any of this sort on the forum, maybe I'm doing something wrong while searching. I'm not sure if I'm being impractical but I was of the impression (from the photos I've seen) that these type of tubes were approx 290mm long the most!! Any further advise / pointers of where I can purchase such a laser?
Thanks

[marting]

Hi Again,
After having posted my previous reply, I have come to realize that these lasers are normally and probably fitted in a stationary position and the mirrors or prisms divert the beam! in which case is a bit out of my hand due to the way my machine is built. However I have seen other CNCs with the laser fitted vertically on the gantry head which is how I want it but having thinking further into the setup, the laser will probably be damaged due to vibrations or the least have it's life expectancy drastically reduced. Hoooo!!! now I'm really getting confused with all this if, but and or situation I think I should look for more information about how these are actually fitted into a cnc.

Thanks

[zax15uk]

If cost is a major factor you'll be looking at a glass tube, in which case mounting it on the gantry is not recommended. I know it's been done but as you mentioned vibration and other issues are significant concerns.

The alternative would be to mount it along the side or back of the system and use mirrors to direct the beam to your focus lens. This is generally the better method except on very large travel systems.

Another alternative would be an air cooled RF excited metal tube like those from Coherent, although these are more expensive, especially the shorter folded waveguide designs that are ideal for gantry mounting and can replace the router head or sit along side and enable dual purpose operation.

You mention your machine design makes static mounting difficult, I haven't seen a system where it can't be done (yet). Do you have a photo of your machine? Perhaps I can offer some advice.

Zax.

[marting]

Hi Zax, the problem is a combination of many.
To start off with are the major: Financial funding is an issue but even worse is due to very limited workshop space, I designed my CNC in such a compact manner to utilize as much as possible of it's foot print for the working area and when designing it, I never considered fitting in a laser. So there are many things in the way for a straight forward fitting without functional modifications. Further more in order not to bother the neighbors with any noises generated, I enclosed it in a sound proofing case so much so that with the door closed all one can hear is sound of a vacuum cleaner on low speed. I guess I'll have to shelve the project for now.
Thanks

[Tweakie]

Hi Martin,

If you do consider a CO2 tube then it is probably not a good idea to even think about mounting it vertically. The cheaper, China import, tubes can make quite a lot of internal debris (from the gas or the electrodes, don't know which) and if it lands on the surface of a mirror it will almost certainly cause damage and degrade performance. The more expensive tubes, made in the USA and used for medical equipment perhaps don't suffer with this but the tube cost is many times that of the China types. Synrad do not recommend that their RF tubes are mounted more than a few degrees from horizontal for just this reason.

When I fitted a laser to my CNC Tweakie.CNC - CO2 Laser Cutting. I purchased as many parts as possible 'second user' but the cost was probably still over the $1500 so I think you must expect it will cost around that mark.

Good fortune with your project.

Tweakie.

[bpoulin]

With your machine being totally enclosed you would have to go with a stationary laser tube, which also may not be practical. By the time you retrofit your CNC you could probably buy a stand-alone laser system. But then you have the space issue... So you seem to be in a bit of a catch-22.

[marting]

Hi bpoulin, indeed I am in a catch-22 and that's why I'll have to shelve it for now untill I find somewhere with some more space ..... in the mean time I'm planning to start designing my 2nd cnc build. Thanks to all of you for the input.