Newbie- X2 CNC Parts Review

[webgeek]

Hi all; I've been around this forum for a long time but never really posted much. I bought an X2 from Harbor Freight with the intent to ultimately CNC it. I opted to wait for the CNC as I figured I'd use it plenty with it set up manually. Interestingly enough, I was wrong. I rarely use the machine for anything and it's basically gathering dust. Much of what I want to make is far beyond my skill to make manually but well within my skill to make via CNC. In order to actually use the machine and start making things, I need to CNC it as I originally planned.

After much research, here are the parts I'm thinking about:

Electronics:
3 x 380 oz-in Nema 23 Stepper Motor
http://cncrouterparts.com/product_in...products_id=42

1 x Gecko G540 4 Axis Stepper Drive
http://cncrouterparts.com/product_in...products_id=40

1 x 48V 7.3A Power Supply
http://cncrouterparts.com/product_in...products_id=41

Kit:
CNC X and Y-Axis Motor Mounts and Screws for Mini Mill
http://www.littlemachineshop.com/pro...ory=1687114045

CNC Z-Axis Motor Mount and Screw for Mini Mill
http://www.littlemachineshop.com/pro...ory=1687114045

Assorted parts:
1 x e-stop switch
? x limit and home switches

So now some questions...
1) Is this a good motor + PS set up for an X2? I'd like to be able to machine most anything but speed isn't a huge concern. I'm fine with taking small passes if needed for harder materials. I figure aluminum will be most common with some mild steel next and lots of plastic for kicks. I love the idea of beautiful parts out of plexi - just too cool for words.

2) Is that conversion kit any good? I've not been able to find anyone talking about it so I'm a bit nervous. I like that it requires no drilling or tapping into the existing mill which is nice. I've read that one of the other popular X2 kits has the z-axis lead screw on the left side and several people have complained about it bitterly and even had to move it around. I'm certainly not interested in that headache. I'm pretty much open to any mostly turn-key kit. I want to avoid a lot of initial machining though.

3) http://www.kelinginc.net has multiple CNC packages (even with the 540) and people seem to like them, is one of those packages a better choice? They require more wiring but I'm a pretty fair hand at electronics so that's not a concern if it's clearly a better choice. Same goes for any of these: http://www.probotix.com/3_axis_stepp...r_driver_kits/ They are certainly very inexpensive!

4) Can someone explain how the home and limit switches are supposed to work? I don't mean so much electronically as much as just how they are positioned. Are there eight limit switches at the max extent of travel in all directions and then a further three home switches somewhere?

Thanks in advance for all the help, this forum is great!

Mike

Edit: added Probotix link too.

[tumutbound]

Check out this thread for answers to most of your questions.

[Dougal]

Why does everyone now go for 380 oz-in steppers?
Even the 280's can provide ~250kg of thrust, which is far more than the 350w motor is capable of using.

[hoss2006]

The parts from cncrouterparts.com look good, the motors have a little higher inductance than the keling 381's, would cost a little top end speed but the prewiring for the g540 is certainly is nice.
prices are similar too.
You'd be better off spending another $100 and getting the ballscrew kit conversion from Cncfusion than
the kits from LMS.
The Z is a problem for some but not most.
You only need 6 limit switches total, one for each end of the axis' travel.
they can all be NC wired in series and 3 of the switches will double as your home switches.
this only requires 1 input on the g540.
Hoss

[kanton]

What kind of limit switches are used with the G540? Are there any instructions to show how to wire them?

Thanks

[Crevice Reamer]

This is one way to do it:

http://geckodrive.com/upload/G540%20REV3%20MANUAL.pdf

Or, you can do as Hoss wisely suggests and wire all of the switches in series, say to pin 1. This will leave pins 2, 3 and 4 for other uses.

CR.

[webgeek]

Alright, thanks for the help thus far - I've gone ahead and ordered the electronics - specifically:
3 x 380 oz-in Nema 23 Stepper Motor
http://cncrouterparts.com/product_in...products_id=42

1 x Gecko G540 4 Axis Stepper Drive
http://cncrouterparts.com/product_in...products_id=40

1 x 48V 7.3A Power Supply
http://cncrouterparts.com/product_in...products_id=41

Based on tons of research, discussion and advice, I'm going to use the CNC Fusion kit #4:
http://www.cncfusion.com/minimill1.html

This comes with ballscrews but I'm quite confused - is this the same as the "pre-loaded ballnut" option or should I get that too? Is it even necessary on a mill this size?

Also, what about the zero-backlash couplings. Is that something I should invest in from the get-go or will the couplings that come with the kit be good enough?

I'm planning on milling PCB boards, mild steel, aluminum, various plastics, and a little wood. I expect that plastic, PCB, and steel will be the majority.

According to a friend of mine, it's a real pain in the butt to mill PCB traces so now I'm quite nervous about it. That was one of the things I was really hoping to do. He got so frustrated with the poor quality of his boards that he gave up on milling them entirely and that's not something I want to do. According to him the traces were just not clean enough the thickness was all over the map. Honestly, it sounded like backlash and a mill that needs trammeling but he says it's due to flex in the board when clamped. Either way, I don't want this to be a problem so I'm trying to head off issues in advance.

Thanks again for all the help!

Mike

[kawazuki]

Not that i've ever done or am likely to do any PCB milling but would have thought that if you factor in your actual measured backlash into your pcb trace widths it could be accomodated. So if you want 0.065" traces and back lash is 0.005" just make them 0.070" wide in design and accept some might be 0.065" and others 0.075" when finished?

Sticking the board to a ply or aluminium backer with double sided tape should cure any flexing problems when clamping?

The Fusion #4 is a good kit and if ordering the preloaded nuts as well should give lash in the order of 0.01 - 0.005" at worst / best but if you want tolerances in the 0.001 - 0.0005" range you maybe disappointed without further work and possibly expense! IMHO

[webgeek]

I'm not really a tolerance nut - I just want to be able to make some things that look and work pretty well. Him talking about how his traces were unusable really made me nervous so I had to ask.

Stupid question - is an e-stop switch NO or NC? Thanks!

Mike

[kawazuki]

Most are NC in use and go NO when pressed so any wiring break for example will also trigger an e-stop

[Crevice Reamer]

If you want good precision and low backlash, go with both the preloaded ball nuts (This means they are filled with oversized balls) AND the helical couplers. The CNCFusion lovejoy types that come standard seem to always loosen up to a lot of backlash.

You will need a higher speed spindle to drive the small bits--DEFINITELY go for the belt conversion.

CR.

[webgeek]

Ah, NC to catch a bad connection - makes good sense. I should have thought of that.

Thanks CR, that info was what I needed. Raises the price quite a bit more than I was planning on but I guess it's the cost of doing business as they say. The belt conversion was on my "must do" list already but I don't plan on getting it from day one.

Thanks again to everyone!

Mike