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QSwitched Lasers?
#1
What is the feasibility of using QSwitched lasers?  I realize it means the laser is pulsed at a high frequency making a higher power pulse.  Often when looking at fiber laser sources on alibaba/aliexpress I find high powers at "reasonable" prices, which I assume are QSwitched sources.  

Also, if interested, I have a CNC machine shop....I could probably make some prototype parts for you a little more accurately than a 3d printer.  My shop is mostly for an unrelated project, but I have many side projects....like I may one day finish my larger scale 3d printer, robotic rtkdgps controlled lawnmower, and more!  I have a 4 axis lathe and a 5 axis mill.  (though the 4th and 5th are removable and not currently on the machine....it barely fits!)

3d printing in metal at home is something I really want to see happen.  I think reprinting your argon nozzle to be closer to the print bed would help.  Also, you may want to flow the argon past the laser to help cool it.  Coming out of the bottle, it should be cold.  It would also help to fill that cone at the top, and neck down to shield the print.  Someone here should be able to do a simulation to figure out the best point to insert the argon, best flow rate, etc.
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#2
So, I did some more reading, these cheap sources are "Quasi CW".  Still pulsed, but longer pulses.  They actually seem to provide some benefit in that they have a high initial energy, followed by a dwell, followed by a ramp down.  The 500W versions seem to have a 120W average energy, so I assume it could be used at the same speed as a 120W CW system?  Not really sure.  The page I found describing the QCW systems was Quasi Continuous Wave (QCW) Fiber Lasers | IPG Photonics
an example of a unit "reasonably" priced: 30W/60W/80W/1 O0W QCW Fiber Laser Series Fiber laser|Laser Welders| - AliExpress Looks like $1000 for 120W average power.  There are others out there.  A 500W CW system can be had for about $3K, so its not horrible, but certainly not worth spending for proof of concept...
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#3
I stumbled across these on Aliexpress a while ago while looking for alternatives. A lot of the sellers advertising these seem to have very poor feedback. I would like to know whether they would be suitable as well, if they are actually obtainable for that price. Their beam characteristics seem far more favourable for our interests.

Thanks for your offer of help. It seems like machining will be inevitable so I will keep that in mind.
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#4
I have a feeling this listing may be more of an accurate reflection of their pricing: link
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#5
Hmmmm.....maybe I'll have to risk some money Big Grin

Other than just getting some goggles, a lens, and some sheet metal, have any better ideas for a test?  Id like to have a simple, non time consuming test...
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#6
Just a small update....I do want to try some fiber laser source, maybe even risking on one of these poor reputation aliexpress vendors, but I'm looking for lots of functionality. Metal printing would be awesome, but its not a sure bet. So while I want to tinker along with my bigger project, I need immediate value if I'm going to spend money. To that end, I took a baby step....I mean, a real tiny step. I ordered a CO2 laser cutter. Nope, it can't do anything with metal...at all...well, it can etch resist for PCBs...but thats not metal directly Smile It does get me a large XYZ linear motion system, and lets me cut many organics. I have several projects on hold for needing that capability, so I do get immediate value. I might even be able to sell some of them Smile The internet has several examples of people adding both Nd:YAG and fiber lasers to CO2 laser cutters - reusing the XYZ linear motion system, but now being able to cut metal. So I wouldn't be breaking any new ground adding a fiber laser source to a CO2 cutter, and I'm sure you can see where this is going Smile I spent close to $1k extra getting the motorized Z axis of significant depth. Deep enough to drop at least a small powder bed system in Smile Again, I don't think I'm breaking any new ground here, as I have seen many other things, like sand molding systems dropped in high Z depth laser cutters. So, it all adds up to immediate value.

My original topic here was on QCW lasers though, and, I am noticing a distinct lack of them. In fact, I am only seeing them from the vendors with a bad rep! This makes me wonder if people are buying them and giving bad feedback because they thought they were getting CW lasers for that price! Feedback is such a touchy thing...all based on emotion, and expectation. I can easily see of someone could think they were getting a 1KW CW laser based on the model number, ignoring the Q in front of it, or thinking it was "meaningless". However, I was motivated to look for other options. I found used/refurbished CW sources for similar prices but higher power. 500W for $2k, and 750W for $3.3k. More than I want to spend at the moment, but still interesting. The used sources likely don't come with the fiber cable or a chiller, so that has to be factored in, as well as the focusing head. I just think there may be a good reason for the bad reputation. (Unfortunately, I do not see a way to see what the feedback was). When I order a fiber laser, either way, I'll start a project thread rather than continue posting in here. I know the QCW sources are way more interesting for the purpose of printing, but a 500W or 750W continuous source is really really really tempting!
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