Originally Posted by
bobby milam
It seems that this thread has made some think that the aluminum isn't a good machine.
Good thing nobody has thus far brought up how well carefully built wood frame Solsylva machines can do, to include light aluminum work. If interested, watch Alex Crane's Youtube videos cutting guitar body from wood and an aluminum part, plus others, as examples.
Art,
I still think you have some research to do. Again, I highly recommend spending some days on the CNCZone DIY build forums to get a better feel for the technology. It is good that at this point you realize you don't know everything and are asking the right questions and weighing against what you realistically think you'd like to accomplish. I've seen a lot of build logs started by people who think they know way more than they do; usually those never get beyond the design stage.
I firmly believe that the CNCRP 24x48 is an excellent choice and one that you could inexpensively and easily grow to a "full-size" machine yourself. You may want to investigate the recommendation for NEMA34 stepper motors versus much less expensive NEMA23 setup--looks like ~$1K difference. If you do determine you truly need and want the NEMA34s, then you may want to also investigate using servo motors rather than steppers for improved reliability. I've seen a lot of discussions about 34s being slower than well chosen 23s at the same gearing/resolution, something you would better understand than I given your background.
My machine's gantry is probably about 1/2 to 1/3 the weight of the CNCRP's, but I can reliably rapid at 840 IPM while temporarily using lower capacity resistors in line with the steppers (I did hit 1200 IPM while tuning my settings, but it was just too much for a mid-size machine and it was getting some errors/locks--the limiting factor, I believe, was the controlling computer, a dual-core Atom CPU). For reference, I'm using dual CNCRP rack and pinions for my X direction with 381 oz-in steppers, 48V power supply, essentially the same stepper drivers as used in the Gecko G540 box, and 2.5K Ohm resistors (versus 3.5K optimal--trying to keep heat down until I can properly heat sink the drivers). Rapids speeds are nice to position the router (and brag about), but probably won't make a whole lot of difference on artistic/intricate/small jobs where the head doesn't move far "in the air" during a particular job; different story for large jobs where the head has to reposition long distances over large material. The cutting speeds I choose are much slower, I'm not sure I've ever set a job to run at over 150-200 IPM for "generic" straight cuts mainly due to the size of my jobs, experience level, and not wanting to break bits. Acceleration is usually much more a contributing factor for smaller/artistic/intricate jobs than IPM; for instance, when cutting lithophanes, I've never seen the IPMs go over 100 and usually are under 50 during the job due to the constant up/down Z movement that causes the X or Y to need to slow down.
Roy
Roy
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G.Weike 80W LG900N 600x900mm laser
LaserCut 5.3, CorelDraw 12, Inkscape, TurboCAD 19
Homemade 3-axis 18x51" CNC router
Vectric Aspire 8, PhotoVCarve, Mach 3
EurekaZone track saw system