Couple servo questions, and X2/X3 advise needed.

[clytle374]

I've got an X2 and desperately want a CNC. I'm a CNC machinist by trade and currently repair machinery(mostly manuals). I've also worked for a undisclosed CNC manufacture, so I'm a little embarrassed to ask the servo questions. Forgive me, I didn't work in design.

Should I sell the X2 and buy a X3? The X2 is quite small, but at least doesn't have a quill. I hate quills on CNCs. I can't find the HF X3 for sale anywhere. Are there any other larger mills in the $1000 range? One more thing, why does no one sell stripped machines for CNC conversion? Has anyone added up the necessary parts from little machine shop to build one from scratch without all the screws, gearbox, spindle drives, or quill?

I have some new Omron servos I got for almost free. And I really want to go servo drive. The Omrons(R88Mxx 200V AC) I believe they are the re-branded Yaskawa SGDs. So the SGDA SGDB drives should work, or the Omron drives. I think I remember one other brand being the same thing, anyone know? They are quite small 50W and 100W, so torque is low. But wattage wise they are comparable to many steppers, and I figured that belt reductions are mandatory anyway, and servos have the speed to make up for it. Power wise(watts) it looks okay. Is this way too small? What am I missing in the 'servo torque' vs 'stepper torque' comparison?

Are the SGDH drives the new proprietary ones? What other drives are compatible? I have no experience with them, and am trying to get my head around the different models. Anyone have a chart or reading to bring me 'up to speed' on the different models?

I have read several people here claim that the drive wattage must match the motor, I know this is not true with the SGDA and SGDB drives and motors since we did it all the time and changed a parameter. I would like to get larger drives (300-400W) in hope of building a larger machine later.

I'm planning to use EMC since I'm a Linux fanatic. Control either a Motenc-Lite or one of the Mesa boards when I can sort through the documentation and figure out what it does. The Servo-to-go card might be the answer since it would be more 'future machine' compatible. It has to be able to run 4th axis, I already have a little rotary table. Open to suggestions here.

Funny note. I signed up here in 2003 when I bought the X2 planning to convert it. Well, life changes, and changed back. I finally made my first post yesterday.

Cory

[hoss2006]

I wouldn't bother with servos on an X2, nothing to be gained over steppers.
The $950 G0704 would be a good candidate for a servo system.
I've debated it but may leave servos for my ZX45.
The RF45's can do some serious milling and go for around $1400.
Hoss

[clytle374]

I wouldn't bother with servos on an X2, nothing to be gained over steppers.
The $950 G0704 would be a good candidate for a servo system.
I've debated it but may leave servos for my ZX45.
The RF45's can do some serious milling and go for around $1400.
Hoss

I had missed that one, thanks. Is it one of the 45s, X3, or something else? Sorry, I'm still a bit behind on what is what.

[SCzEngrgGroup]

If you're used to working with "real" CNC machines, I would think you'd find working on most of these small machines painfully slow, with their slow, low-power spindles, and flexy frames. I'd suggest you buy the biggest machine you can afford. I would think an RF-45 would be your best bet, as it's about the biggest, stiffest thing you'll find short of the Bridgeport, or a used VMC. Then again, used Bridgeports can be had awfully cheap, if you're patient....

Regards,
Ray L.

[clytle374]

If you're used to working with "real" CNC machines, I would think you'd find working on most of these small machines painfully slow, with their slow, low-power spindles, and flexy frames. I'd suggest you buy the biggest machine you can afford. I would think an RF-45 would be your best bet, as it's about the biggest, stiffest thing you'll find short of the Bridgeport, or a used VMC. Then again, used Bridgeports can be had awfully cheap, if you're patient....

Regards,
Ray L.

Oh, it is completely horrible. Not to mention I'm not any good at a manual machine either.

Cheap Bridgeports don't come around locally, still high tech equipment around here And they are trash by the time someone gets rid of them.

Not much room for a Bridgeport, VMC is out of the question.

What are the options for the RF-45, who sells them?

[SCzEngrgGroup]

Oh, it is completely horrible. Not to mention I'm not any good at a manual machine either.

Cheap Bridgeports don't come around locally, still high tech equipment around here And they are trash by the time someone gets rid of them.

Not much room for a Bridgeport, VMC is out of the question.

What are the options for the RF-45, who sells them?

RF45s are available from Grizzly (G-0519), Enco, Lathemaster, Penn Tools, and several others. The "Big Kahuna" of RF45s is the Industrial Hobbies, which is bigger, heavier, stiffer than any other, but also more expensive. The RF45s are about the biggest, baddest "benchtop" machines there are. The Grizzly is nice, as it comes with a 3-phase motor. Add a $200 VFD, and you have variable speed. All the others are single-phase, so require swapping out the motor to get variable speed. And, of course, Grizzly machines are generally considered to have slightly better quality control, and definitely better customer support and parts availability than most.

Regards,
Ray L.

[hoss2006]

I had missed that one, thanks. Is it one of the 45s, X3, or something else? Sorry, I'm still a bit behind on what is what.

I wrote up an excel breakdown of several of the commonly available RF45's when I chose mine recently.
http://www.hossmachine.info/RF-45_Clone.html
Some come with more bells and whistles than others.
The G0704 is in the same size class as the X3, neither come close to the RF45's.
Hoss

[hoss2006]

My mill comparison page will give you an idea of the sizes of some of these mills.
http://www.hossmachine.info/Mill_Comparisons.html
Hoss

[clytle374]

My mill comparison page will give you an idea of the sizes of some of these mills.
http://www.hossmachine.info/Mill_Comparisons.html
Hoss

Thanks. Hey I noticed you were quoted shipping to "WV", if you mean a state in the US, we're kinda neighbors.

Now to figure out what machine I can afford, and still afford some electronics. The HF45 is gonna need bigger servos? Or more reduction.

[clytle374]

Sadly, I'm back to the original problem. Afford bigger mill or CNC. Being I can't do much of anything on a manual, looks like CNCing the X2 is the way to go.

Any advise on servo sizing?

[SCzEngrgGroup]

Sadly, I'm back to the original problem. Afford bigger mill or CNC. Being I can't do much of anything on a manual, looks like CNCing the X2 is the way to go.

Any advise on servo sizing?

Putting servos on an X2 is putting lipstick on a pig - there's just nothing to be gained. My stepper-driven X2 will do 270 IPM rapids (which is ridiculous on a machine with such short travels) and has more than enough thrust for any operation it's capable of performing. Servos have no advantage, unless you consider higher cost and complexity an advantage.

Regards,
Ray L.

[BobWarfield]

Sadly, I'm back to the original problem. Afford bigger mill or CNC. Being I can't do much of anything on a manual, looks like CNCing the X2 is the way to go.

Any advise on servo sizing?

Like the folks are saying, unless you can get your servos more cheaply than steppers (perhaps they're surplus from your business), there's no reason to use servos on the small machine.

Mariss F. (Mr Geckodrive) has some neat calculations on where he thinks the breakeven point of choosing servos would be:

http://www.geckodrive.com/faq.aspx?n=720465

You'll also like his "Top 10 Stepper" and "Top 10 Servo" advantages on that same page to tell you the tradeoffs. He sells both step and servo drives.

Before you get too far down the road, if you weren't already aware, be sure your drives take step and dir inputs for either EMC or Mach3 compatibility.

Lastly, Hoss is one of the (no, probably THE) expert on what you can do with an X2. Peruse his site. In particular, this page is a gem of concise goodies:

http://hossmachine.info/Shop_Info.html

Note the links to increasing travels and increasing column rigidity. The X2 can be a "bigger" machine than you'd think, both figuratively and literally. I really like the idea of putting a much stouter column together for it.

That newer mill from Grizzly that Hoss sent you a link to, the BG20, is likely a lot more mill though. It seems to be the champ in the range between the X2 and the RF-45 if your budget will bear it.

Cheers,

BW