[Riceburner98]

Cleaning up a bit so I can walk around in my "shop" room, and wondering what to do (like I don't have enough projects) with this XYZ stepper-driven table I have.. All 3 are Parker-Daedal 6"x6" tables on small linear ball ways, X and Y are stacked on each other, with the Z on a big right-angle plate on top of the Y. They each appear to have high-resolution optical linear encoders, I *think* 4" of travel.. (been a while since I moved the axis..) All are brass anti-backlash ACME nuts on precision leadscrews, the Z is .1" per turn, or .0005" per full step (.00005" per 1/10 step). The X and Y are .02" per turn, or .0001" per full step (.00001" per 1/10 step). I hooked up the drivers to a frequency generator and had to crank the step pulses into the Megahertz to zip them along. I think the drivers are set to 1/256 step, which is insane. (and probably way beyond what typical steppers will even go down to)

I have no idea what the backlash would be like for "machining", I don't even know if it would really be fast enough for "real" machining, more like super-precision engraving, or milling some dust from metal. It was originally set up to move a very light object around in front of a microscope lens, really really precisely.. I would get a picture, but the cables are all wrapped around it and I don't really feel like unwinding it all at the moment. There's a crazy-expensive (when new) Parker 6KE 4-axis controller with it that I assume would read the linear encoders, but not likely that's going to play well with Mach3 or something like that.

I saved it from the trash with the intention of doing something useful with it, but so far it's just been collecting dust. On the opposite end of the spectrum, it's actually sitting on top of a 24" x 24" or so ballscrew-driven XY table that's got to weigh 150 pounds. That's got a huge open area in the center (like the X and Y are big open window frames with the bearings and ballscrews around the sides), I think it was used for some optics application that needed a big open center to look through.. Another machine? I was thinking I'd just use it for the 22" ballscrews, but I'd hate to junk the rest. Ugh. Not enough space for all these projects!

[macpod]

PCB milling setup?

I favor having someone in China make my PCBs for 20$ or to chemically etch them personally.. but that doesn't mean the idea isn't there.

Edit: Watchmaking?

[sansbury]

eBay it, spend the money on something practical, and let some other sucker figure out what to do with the "awesome deal" he just got

EDIT: I'd ask on the emc-users mailing list (and the Mach forums) about that Parker controller. A complete instrumentation-quality 4-axis drive system might make a killer setup on a Taig or Sherline. You might be able to fit larger encoders to get more travel. Or maybe just eBay that separately....

[Riceburner98]

LOL... I thought about using it for PCB's, but I too would rather just send them out to be made. ExpressPCB is cheap enough, and boards come back better than I could make in just a couple days. Watchmaking.... A friend of mine wants to start making custom shirt buttons with designs machined in them. I thought about using it for that, but don't know if it would be fast enough. Might be a "hit run and go to work" thing assuming it would run OK unattended. I haven't actually tried it with Mach to see how it would perform.

Thought about Ebay'ing it, but the similar Parker parts were getting 0 bids. I'd hate to just give it away. Maybe if I stuck a Wolfgang or similar spindle on it and sold it off as a complete machine.. Though if I do that, I'd probably want to keep it.

Any idea if the Parker Zeta drive thing could interface with Mach? There's a huge manual about programming it; I just figured it was meant as a stand-alone thing, but maybe it could talk to Mach and take Gcode.. Hmm. I thought about using the 3 driver modules with the new mill I'm working on, but I'd need to buy a 4th and I can't tell which on eBay are the same / close enough. There's one with the exact same P/N, but of course it's $$$$. Some that look identical are much cheaper, but the P/N is a little different. They seem like awesome drivers, with built in 120v AC power supplies, electronic damping / anti-resonance, and up to a ridiculous 256-microsteps/step. Very solid units.

[HawkJET]

ExpressPCB is cheap enough, and boards come back better than I could make in just a couple days.

I agree completely! I started to CNC a PCB but my senses got the better of me and I sent it off to ExpressPCB... I made my own BreakOut Board with ExpressPCB.

Any idea if the Parker Zeta drive thing could interface with Mach?

I quickly googled Parker 6KE and didn't find anything. If it is a 4 axis controller, Mach3 will replace it and be FAR easier to use! Mach will not talk to it - there is no need for it if you have Mach3.

I thought about using the 3 driver modules with the new mill I'm working on

I HIGHLY RECOMMEND doing exactly this!

I'd need to buy a 4th

I saw one last week for $75 (buy it now). I almost got it (But I have a dozen already).

I can't tell which on eBay are the same / close enough.

The numbering system is deceptive. It just has to be the same kind. If it is a ZETA4 stepper drive, they are all basically the same.

They seem like awesome drivers, with built in 120v AC power supplies, electronic damping / anti-resonance, and up to a ridiculous 256-microsteps/step. Very solid units.

I never could understand the need to have a power supply (a la Gecko) when the driver is basically already a switching power supply. I understand that the lower voltage components are cheaper so Geckos can hit their price point (don't get me wrong, Geckos are FINE drivers, I just have a different engineering philosophy). But the separate power supply is redundant. These Compumotor units are VERY solid (that's why I have a dozen or so). I highly recommend keeping them and using them for your project.

I'm using ZETA drives on my Bridgeport Series I Boss3 retrofit. http://www.cnczone.com/forums/bridge...it_anyway.html

I can assist you in using these drives if you wish (even show you how to double their current output).

[Riceburner98]

Wow, good stuff! I thought the part numbers were odd.. Probably like the visions systems the place I work makes; base part is the same but customer can order different firmware versions, which changes the end part number..

It's great to see someone else using these drives. The only reason I can think that more people don't is they just don't know better.. The price on eBay isn't bad at all when they come up for what you get. I'm curious about the current doubling - did you replace any parts, or just tweak something inside? I doubt I'll need more than 4A per stepper with my fairly small machine, but you never know..

My fat fingers seem to have typed "Parker 6KE" instead of "Parker 6K4". Whoops. There's a few of them on eBay for ridiculous $$. I like Mach and have always used it (I did boot up an embedded PC with Unbuntu and EMC for about 10 minutes, but never actually ran a machine with it), I just wondered if the 6K4 drive would produce any smoother or "better" motion considering how much the thing cost new. Maybe it's just expensive because it replaces what a PC would do..? Though I guess you wouldn't use Mach to control an industrial machine anyway, so you'd need something like that.

I'll have to keep an eye out for Zeta drives on eBay.. I don't think the $100-ish ones are too expensive, but if I see any for less than that I'll have to think about picking them up just-in-case. I currently use IM483 drivers which I got on eBay, and now I have a dozen or so of those. They work WAY better than the Xylotex board I started with, for the same or less money. We still use them at work in our simple stepper-driven equipment, because you tell them over serial where to go. (I use the step/direction input of course.. Can't do coordinated movement with no way of syncing them.)

[HawkJET]

I thought the part numbers were odd.

They were originally sold as a motor/driver pair. The part number reflects the motor they were paired with. All the ZETA drives are the same, the difference is how the dip switches are preset from the factory. If you use a different motor that needs different current, you just change the dip switches....

The price on eBay isn't bad at all when they come up for what you get.

Geckos cost just over $100 per axis. But then you also need to buy a power supply. I got my ZETA drives for about $100 per axis, but I don't need a power supply. The ZETA drives are every bit as good as Geckos (and vise versa).

One thing you need to watch though, since the ZETA drives use rectified line voltage (170 volts), it is easier to overheat the motors (since it is easier to get higher speed performance). I am building an industrial machine and pushing the motor pretty hard. So I have a fan, heatsink and temperature sensor/interlock to protect the motor.

I'm curious about the current doubling - did you replace any parts, or just tweak something inside?

I have worked for various motor companies for most of my career (I was one of the original employees of Compumotor). So I have a good sense how things work. The ZETA drives are a 15-20 year old design, so the MOSFETs are that old too. I replaced the MOSFETs with newer technology parts with 1/3rd the on resistance and double the voltage capability. With these new parts, the heat generated by the driver is less than original, so the heatsink can handle the higher current. I also had to change the current sense resistors to "fool" the firmware into increasing the current.

Maybe it's just expensive because it replaces what a PC would do..?

They are expensive because, back when they were designed, Mach wasn't around (or at least is was barely known). Also, in those days, the customers for such devices were generally corporations (not hobbyists), so they charged more, plus the market was much smaller. Since the advent of the likes of Gecko, Compumotor is really struggling. Gecko knows how to make a product that is both, very high quality, AND inexpensive to manufacture. Unfortunately, Compumotor did not. The items on eBay are expensive because Compumotor controllers are so specialized that if you have one that fails, it HAS to be replaced with another Compumotor (so they have you by the short hairs).

Though I guess you wouldn't use Mach to control an industrial machine

There is no reason NOT to use Mach3 on an industrial machine. I am currently building a machine to automate the production of a carbon fiber product. That machine is controlled with Mach3 (I started with EMC2 but found that Mach3 is FAR EASIER to customize for special applications). There are a number of turnkey CNCs that use Mach3 (I believe Tormach does).

I'll have to keep an eye out for Zeta drives on eBay.. I don't think the $100-ish ones are too expensive, but if I see any for less than that I'll have to think about picking them up just-in-case.

The $75 price is very rare, which is why I almost bought it.

[sansbury]

(I started with EMC2 but found that Mach3 is FAR EASIER to customize for special applications).

That depends a lot on the application. If you need to build a few custom screens to control a typical machine with cartesian kinematics, then yeah, definitely easier. It will beat EMC in the quarter mile every time. Where EMC shines is when things get a lot more complicated, whether you're doing closed-loop control, complex kinematics like a robot arm, rigid tapping... that sort of thing.

As an aside, I started switching one of my machines last night from Mach to EMC, and right off the bat, I'm able to sustain slightly higher speeds than I could with Mach. Whether this is the PC or the software is impossible to say for sure, since the hardware is different, but I'm not the first person to find this kind of thing.

Likewise, I've long felt that Mach is just plain buggier than EMC. In EMC, things seem to mostly either work or throw errors. Mach seems to have more scenarios where the machine wanders off in a totally unexpected way.

[HawkJET]

That depends a lot on the application. If you need to build a few custom screens to control a typical machine with cartesian kinematics, then yeah, definitely easier. It will beat EMC in the quarter mile every time.

This machine has one linear axis and two rotational (take-up and pay-out reels). The standard Cartesian screens are of little use.

Where EMC shines is when things get a lot more complicated, whether you're doing closed-loop control, complex kinematics like a robot arm, rigid tapping... that sort of thing.

Well, maybe... here is a thread that shows Mach3 running closed loop and doing rigid tapping...http://www.cnczone.com/forums/bencht...g_1000rpm.html

As an aside, I started switching one of my machines last night from Mach to EMC, and right off the bat, I'm able to sustain slightly higher speeds than I could with Mach.

My experience was the complete opposite. I was able to more than double my speed when going to Mach3.

Mach seems to have more scenarios where the machine wanders off in a totally unexpected way.

It has never happened to me and I have not heard of this. Mach works flawlessly for tens of thousands of users. This seems like superstition to me....

[SCzEngrgGroup]

It has never happened to me and I have not heard of this. Mach works flawlessly for tens of thousands of users. This seems like superstition to me....

Hawk,

Nope, far from superstition. Come by my place sometime, and I'll demonstrate some of the many problems in Mach3. Hang out on the Mach3 forums, and you'll see how many people have weird things happen. I've personally reported, and helped track down and fix, a dozen or so mostly pretty serious bugs in Mach3, and there are several more that have been proven, and acknowledged, but not yet fixed, even after several years.

Want to see a good one? Configure your machine so the Z axis acceleration is much less than X/Y (not at all unusual), then program a linear move in X/Y that then transitions into a helical move in X/Y/Z. The Z acceleration limit is not respected, and, on a real machine, the Z axis will fault, or lose position. That one cost me a $100 endmill the first time I encountered it.

If I had a nickel for every time Mach3 has just flat weirded out, and gone "off script", I coulda bought me a VMC by now. I've got quite a collection of broken tools and probes from random, non-repeatable moves Mach3 decided to make all on its own. If I ever have to pause a program, and re-start from some intermediate point, and see that "preparatory move" dialog come up, I STOP, exit Mach3, and re-start, as those moves are virtually NEVER right, and will do such interesting things as send the machine completely outside it's working envelope, or rapid a tool right thought a vice or clamp, taking it completely outside the bounds of the program being run.

And this is across at least three different complete systems, some servoed, some steppered, some with SmoothStepper, some without, completely different PCs, drivers, BOBs, etc, and spanning well over 5 years. Never once had any of these problems with TurboCNC, BTW. Many people never have a problem, many people have frequent problems. I am, sadly, one of the latter, and am seriously considering going to EMC as a result. Mach3 has great potential, but it really is not all that stable, all things considered. And each new release brings a new raft of problems.

Regards,
Ray L.

[sansbury]

This machine has one linear axis and two rotational (take-up and pay-out reels). The standard Cartesian screens are of little use.

Screens and kinematic models are *totally* different issues. Let's say you have a SCARA arm. In this case, moving the actuator at the end of the arm from X=0 to X=1 is not simply a matter of spinning the X-axis leadscrew 5 rotations, you may have 3 or 4 axis moves needed depending on the degrees of freedom on the end of the arm and whether you want to keep the orientation the same. Serial kinematics are a classic example of this.

With Mach, you can sort of handle this, but you need to pre-calculate all the individual axis moves, and even then, you may not be able to keep them perfectly synched during the move, which may or may not matter. With EMC, the motion controller can have a model of the arm, and you can simply issue G1 X1 F5 and it will do exactly that.

Now, does this matter to 99.8% of people here? Not really

Well, maybe... here is a thread that shows Mach3 running closed loop and doing rigid tapping...http://www.cnczone.com/forums/bencht...g_1000rpm.html

As I posted in that thread, I'm curious to understand a little better what's really going on under the hood. That said, the test of what he built isn't what the book says, it's whether the thread comes out right. If it meets his needs, then it works for him.

My experience was the complete opposite. I was able to more than double my speed when going to Mach3.

Yeah, you definitely had a lot of trouble with EMC. This piece of the stack is still a huge mess. I've always had good luck with getting machines up and running but I know enough really smart guys who've had a hard time to know it's a mess. The fact is that using a PC to generate steps is a hack. Art's printer driver is one hack and the Linux RTAPI module is another. It may be a more formal and in some cases better hack, but it's still kind of a hack.

It has never happened to me and I have not heard of this. Mach works flawlessly for tens of thousands of users. This seems like superstition to me....

Well, I don't know that I'd ever use the words "flawlessly" and "software" anywhere near each other

This is a hard situation because there's enormous variation. You have different PCs, then you have different machine configurations, then you have different G-code. Even if you just saw something weird happen on your machine, it can be hard to figure out what got you there, whether it was something you did or the controller, and replicating the bug can be really hard.

Neither Mach nor EMC are anywhere close to perfect. They have different flaws and strengths. If I was a custom machine builder, I can easily imagine projects where I'd choose one or the other depending on what I need to do.

[HawkJET]

Nope, far from superstition.

Interesting....

Both Mach3 and EMC2 are complex programs. It seems that the more complex the program is, the more likely there will be a large number of users with absolutely no problems and those with several - as if they were using different programs altogether.

Ray, sorry to hear of your issues. Good luck if you switch to EMC2.

My sense is that both Mach3 and EMC2 are very comparable, although they have different design philosophies. It is really just a matter of which one fits your application best.

[HawkJET]

Screens and kinematic models are *totally* different issues.

Yes, I agree. I was on a different page in my reply.

Well, I don't know that I'd ever use the words "flawlessly" and "software" anywhere near each other

BUSTED! You really got me on this one

Neither Mach nor EMC are anywhere close to perfect. They have different flaws and strengths. If I was a custom machine builder, I can easily imagine projects where I'd choose one or the other depending on what I need to do.

Very well put.

[ihavenofish]

mach3 sucks. emc sucks. there. i said it.

mach3 has serious issues on contouring at high speed and high detail. bascally it cant figure out how to decellerate when the command is very short - 0.1mm or less in my case. this shows up when you have a sharp corner in your program. it will overload the stepper and cause it to stall. its a massive part and tool killer.

emc has no such issue, however its constant velocity contouring allows it to deviate from the requested tool path ridiculously causing issues like facets, gouges, and out of square cuts. on the bright side this can be tuned out at the expense of speed, without risking damage to your part, tool or machine.

[sansbury]

I completely agree with ihavenofish. This can get a little like Coke vs. Pepsi sometimes and I try to avoid that.

Where EMC sucks is that customizing GUIs is somewhere between hard and impossible, and the underlying configuration of things is at times very opaque. With Mach, simple things are fairly simple, while difficult things are either very difficult or impossible. With EMC, impossible things and simple things are equally possible and equally difficult. The EMC core users respond by saying that Mach's GUI looks silly (one user said it looks like a slot machine ) and by saying that EMC is vastly more flexible. While more or less true, these miss the point.

What Art nailed even with the original version of Mach, was a complete and harmonious stack of tools for integrating a basic machine control with the typical feel of a Windows application. You had the core app, menu-driven configuration, the screen builder, the wizard framework, and the scripting API.

The bottom line is that Mach is a commercial product and thus driven by the needs of the average user. EMC is maintained and run by hardcore enthusiasts who value technical superiority over silly things like ease of use. Even so, compared to a few years ago, it's gotten a lot more accessible, and the upcoming 2.5 release will include a graphical screen-builder (GladeVCP) that will I think lead to a lot better GUI options than we have today.