I have no doubt the machine will have it's limitations. If everything pans out I also have no problem upgrading the belts to a much wider design in the future. The cost of my current belts were dirt cheap in comparison of a wider belt/rack and pinion design and thus why I'm moving foward with this design.
I have $3500 in my machine and just couldn't put in an extra $800 or so for an alternative design when I knew this would get me what I needed (for now atleaste).
For the foam
SB320 (20lbs/cubic foot)
SB240 (15 lbs/cubic foot)
will be what I use.
A belt drive system will work fine if done properly, here is a good example of an ACTUAL working system using belt drive. http://www.cnczone.com/forums/open_s...oot_print.html
I say go with whats known to work in real applications.
Got one side of the x belts attached and tensioned so had a chance to do a quick test. For the x, one rotation on the nema 34 stepper motor is around one inch of movement. This will hopefully keep the precision up.
Current rapid settings
X = 700 ipm
Y = 200 ipm (was a dummy an unloaded the ball screw nut, need to reload it and should be able to get higher rapids.
Z = 300 ipm
The one side of the x that is connected to the belt is super rigid and i don't have any doubts of it not working...yet. So far so good!!!
Made a first part last weekend! Not sure why the z lost steps or slipped on the shaft, but it did and messed up some of the part on the final pass. Tightened things up and slowed things down, only future parts will test the true performance. Have some small changes to make(need to reduce chatter in the z), but very happy thus far!
Guys, figure I got so much help from this site so it's time for a long needed update! After building the machine I got burned out and the wife was like wtf. So she had me start making parts with her designs, made a website and now we have sold enough product to cover the cost of the machine a few times now!
What I have learned: enclosed the sides, added a retractable top and a true duct collection! I cut parts all day long with black cars in the garage and have very little build up! Oh yah, the chinese stepper controllers work really good but are bit noisy and I need max torque so upgraded to a gecko unit (yes I'm driving a nema 34 and a 100 lbs gantry!!). Also, I love the fact I have 18" of z travel but have yet to cut a part over 1" thick :/
Belts...ah the much debated debate, let me just say I have ZERO 'springiness' sure the bottom side bounces a bit, but who cares! Top side is tensioned and that's what drive the gantry. I would do belts AGAIN in a heart beat!
This post is scattered as from the time I built the unit over a year ago we've had a kid, moved to Colorado from Texas and now the kid is back awake so typing as fast as I can. Just wanted to say thanks, buy a gecko g540 for the few hundred more than a chinese, drive a nema 34 if you want, belts work perfect and are CHEAP CHEAP CHEAP, get a wife that can design for you cause I can't design crap and start making some $$. Now onto a hunt for a laser cutter, think I'll buy this one...
Hey guys, just to update you, the BELTS WORKED and this machine was great! I only needed 6" of travel and not the monster 20" but whatever! This machine ran over 2000 parts on 1/2 plywood and was the base of a fun side business to what has grown to a full shop, 5 employees, quite day job dream!
Just so you know, for this size of machine I would do belts in a heartbeat! I'm not sure what people have against belts, maybe it's just the unknown, but they worked wonderful and the cost was so cheap compared to the alternatives. Again, I saw belts work at my last job on a 10'ft long, 5' wide, 3' z, foam cnc machine that was single sided run so many parts!
Just wanted to say thanks for all the input (even those who I didn't listen to). Without this forum I wouldn't of been able to get where I'm at!
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