New Machine Build- 4x6 Cutting area 80/20, sourcing parts.

[Hdale85]

As the title says I'm starting to source parts for an 80/20 build that will have a cutting area of 4'x6'. I already have some parts like 3 Nema 34 960 oz/in stepper motors. I also have 3 Gecko G203V's to drive these steppers. I still need to pick up or build an adequate power supply though. I think I'll do the outsides of my table out of 3060 and then do the inner bracing and what not out of either 3030 or 2040.

One thing I'm not sure on is if I can get away with using a ball screw for the 6ft length? A lot of the other details I'm still working out.

Of course I'm open to suggestions. Unless there is a R&P kit out there I don't have many tools to really fabricate the brackets. Would I need to use a bigger ball screw? I think I may use some of the DIY linear bearing assemblies here on the forums although linear rails aren't out of the question just yet.

[CarveOne]

Originally Posted by Hdale85 As the title says I'm starting to source parts for an 80/20 build that will have a cutting area of 4'x6'. I already have some parts like 3 Nema 34 960 oz/in stepper motors. I also have 3 Gecko G203V's to drive these steppers. I still need to pick up or build an adequate power supply though. I think I'll do the outsides of my table out of 3060 and then do the inner bracing and what not out of either 3030 or 2040. One thing I'm not sure on is if I can get away with using a ball screw for the 6ft length? A lot of the other details I'm still working out. Of course I'm open to suggestions. Unless there is a R&P kit out there I don't have many tools to really fabricate the brackets. Would I need to use a bigger ball screw? I think I may use some of the DIY linear bearing assemblies here on the forums although linear rails aren't out of the question just yet.

Keling Inc. has a couple of unregulated 72vdc power supplies that will do the job. A number of builders here are using them, and I just recently purchased the 20 amp version for my build. Haven't wired anything up yet, but I'll be at that point real soon.

Cncrouterparts and FinelineAutomation will be releasing an R&P drive and racks soon. Keep those in mind before ordering long ball screws.

CarveOne

[Hdale85]

Yeah I've been looking at their threads but partial problem is they wont have Nema 34 mounting atm and not sure what the cost is going to be or how long before they release them. We'll have to see.

Thanks on the PSU that's one of the ones I had seen.

Looks like they have an 82v as well. Of course its quite a bit more. I think my steppers are 90v but the 72V would probably work fine.

http://www.kelinginc.net/KL-8215.pdf

[LeeWay]

Your Gecko's are only rated 80 volts, so I would lean toward the 72 VDC.

[Hdale85]

Oh ok, you're right hah. I thought I had read they were rated higher. So yeah the 72v is certainly the way to go Not sure the extra voltage would help me out much anyways I'm sure I'll have more then enough torque seeing as I'm using steppers that are roughly twice as powerful as what most are using here.

[Hdale85]

Do you guys have any examples of a rack and pinion setup with very detailed pics of the R&P in particular. I'm trying to decide if it's something I can machine with a saw and a drill press.... Kind of thinking no at least not with much precision.

[CarveOne]

Originally Posted by Hdale85 Oh ok, you're right hah. I thought I had read they were rated higher. So yeah the 72v is certainly the way to go Not sure the extra voltage would help me out much anyways I'm sure I'll have more then enough torque seeing as I'm using steppers that are roughly twice as powerful as what most are using here.

The G203Vs over voltage protection circuit shuts down at 80Vdc. The Keling unregulated power supplies are rated at no load current, and the output voltage drops off as the load current increases. At full rated load it is around 55vdc as I recall the specs. You will get higher torque out of your motors at full speed with more voltage input. Even at 55vdc you will have more torque than running them at 24 or 36vdc with other drives.

All this extra torque just means that you can twist those NEMA 34 motors right off the mounts when you run into a serious sudden stall situation. If you do that, show us the video please....

CarveOne

[Hdale85]

Hmm well hopefully that does not happen. Are you saying that I should of probably gotten some lighter duty steppers? I got these because I won them on ebay at an incredibly cheap price (200 for all 3) several months ago.

[Hdale85]

The main reason I was happy with the 960 oz/in motors is that eventually I'll slowly upgrade my first machine and when I buy a welder I'll start on a second machine that I'm hoping will be steal and quite a bit heavier. I was figuring I could move most of the electronics over to the new bigger machine that would mostly be for aluminum work and if I decide to keep both machines I can find a good deal on a G540 and some matching Steppers. So I was hoping that the 960oz/in wouldn't be too much for this machine. I guess I'll just have to keep an eye on it.

[CarveOne]

I doubt that having motors with that much power is a bad thing. You could probably power a Mechmate with those if you wanted to. Since most of the machines in the 4' x 4' size and smaller are happy with much smaller motors 960 oz-in just seems like a lot of excess power. I was kidding about the sudden stall scenario. You'll need to be sure you pick a driver that works well with the inductance and phase current of those motors. Gecko G203V drives can handle 7amp motors. G540 may not be able to handle your motors.

CarveOne

[Hdale85]

Yeah I have the G203V's right now.

I'm just trying to figure out the rack and pinion thing. Seems part of the speed problem with some of these are from the ball screw so seems a R&P setup is better in regards anyways.

I'm also thinking about getting a real spindle. I've been looking around on ebay and what not. I know some have used the Chinese spindles with some luck. I'm not sure if I want to go that cheap but it seems the next best option is 2k. So maybe the Chinese ones are worth a shot lol. There was a couple I saw that I could possibly swing for but total cost with VFD is going to be ~2k or so. The Chinese Spindle I was looking at was 3KW water cooled with VFD for 650 or there is a 4KW with VFD that's air cooled for 800. Was looking to spend ~1k for a Spindle but it seems the nicer brands are quite a bit more.

These are the couple others I was looking at.

http://cgi.ebay.com/ws/eBayISAPI.dll...=STRK:MEWAX:IT

http://cgi.ebay.com/ws/eBayISAPI.dll...=STRK:MEWAX:IT

Not sure if those models would be much better but I believe they will run at a lower speed then the Chinese one. From what I understand the min speed seems to be 10k RPM for the Chinese models although not sure how accurate that is? I'm not real sure if 10k RPM is slow enough for good aluminum work.

I may go with Joe's Hybrid kit to get me started and then slowly modify it cutting new parts out of aluminum instead of MDF and HDPE for the gantry and what not with the machine.

[CarveOne]

Anything with much over 4' of travel need something better than ACME screws. R&P is the only real solution for long lengths of travel. They can be a little less accurate over long distances depending on tolerance buildup. Software based error compensation can help with that. I think Mach3 has that capability.

From reading the Chinese spindle threads it appears that the Chinese spindles have documentation issues and many unhappy users. Until they get that sorted out I would recommend holding off on buying those. You need to be sure you can get three phase power at your location if you consider a spindle that needs it. Colombo seems to be the one to buy. I wouldn't buy one that has no warranty.

Joe's 4x4 builders seem to be really happy with their machines.

CarveOne