Hi guys, hopefully some of you can spare some knowledge to help a newbie.

I'm in New Zealand and have bought a mill that while rebranded, having an MT3 spindle and running on 240v is essentially an X2. So to save confusion I'll call it an X2 from now on.

I plan to convert this to CNC to make what the machine shop boys call rats and mice. the pieces that are too small to bother them with. Mountainbike parts, small car parts etc.
I'm also hoping that with a probe I can use it as a small CMM to reverse engineer parts.

I've been trolling sites like this for a few weeks and the options available just seem to grow rather than shrink. So I need some help nailing down the best collection of parts.
I want ballscrews, that's easy as the CNC fusion kit has that covered.
I'm on the fence regarding servos vs steppers. The absolute positioning of the servos will be a major advantage (I freely admit to crashing and stalling machine tools) and I like that I can buy braked servos which will go nowhere when the power is off.

I have absolutely no idea what control system to buy and I need help here. I would like to run the system from a laptop and will probably have to build/buy a 24v supply. But I would like the rest to be as complete for plug and play as possible.
I'm fairly savvy with electronics, but I'd rather pay for a kit to avoid the hassle.

CAM is something I'll address later. I've been playing around with demos of lazycam as well as cambam and g-simple thanks to finding out about them here. I'm a solidworks user, I have used G-code for industrial automation but not milling and have never used a CAM package before. But I know plenty of people who earn their living that way.

Any help appreciated.

If you are going as far as ballscrews and servos, why a 24v drive and power supply? That would seriously cripple the thing, and only save you a few bucks at most.

BTW, I have brakes on my steppers as well, to both prevent the Z backdriving and hold positions on power off. They aren't just a servo thing.

If you are looking to cut corners anywhere, a servo system might be the better thing to drop. At this size both systems perform the equally well for designed operation, its only when you crash it does it become an issue.
That said, is the fairly significant chunk of extra money worth the occasional instance of having to recut of one of the little 'rats and mice' you might have potentially been able to save after a crash if you had servos? Remember that even with servos few parts can just be picked back up after a crash and resumed. Unless your cuts are very long and your material very expensive or irreplaceable, its hard to justify the cost solely on that basis.
Servos are definitely nice to have, so you could just really want them for other reasons, but the often used reason of recovery-after-crash is not really of much value at all when it comes to this type and size of machining.

If you are going as far as ballscrews and servos, why a 24v drive and power supply? That would seriously cripple the thing, and only save you a few bucks at most.
I had stumbled across one controller that said it needed a 24v supply, what do most require?


BTW, I have brakes on my steppers as well, to both prevent the Z backdriving and hold positions on power off. They aren't just a servo thing.

If you are looking to cut corners anywhere, a servo system might be the better thing to drop. At this size both systems perform the equally well for designed operation, its only when you crash it does it become an issue.
That said, is the fairly significant chunk of extra money worth the occasional instance of having to recut of one of the little 'rats and mice' you might have potentially been able to save after a crash if you had servos? Remember that even with servos few parts can just be picked back up after a crash and resumed. Unless your cuts are very long and your material very expensive or irreplaceable, its hard to justify the cost solely on that basis.
Servos are definitely nice to have, so you could just really want them for other reasons, but the often used reason of recovery-after-crash is not really of much value at all when it comes to this type and size of machining.

Thanks for your advice, since you have brakes on your steppers, is it possible to put encoders for feeback on them as well?
Or would this require a controller that isn't commonly available?

Are the servos available in this size fitted with incremental or absolute encoders? Absolute would of course be best (power up the machine and it knows where it is), but are they available and at what cost?

I had stumbled across one controller that said it needed a 24v supply, what do most require?

Some stepper systems run at 24v, but it is much, much better if they are capable to run at 36 or 48, or even as much as 60 or 72v. I am not a servo expert by any stretch, but they generally run much higher - the ones I have seen have ran at 72 or 90v.

Thanks for your advice, since you have brakes on your steppers, is it possible to put encoders for feeback on them as well?
Or would this require a controller that isn't commonly available?

The brakes are standard Nema 23 items, and it is common and easily done to place a shaft encoder on the rear shaft of double shaft steppers (its generally why the second shaft is there). Mach3 controller software can accept the standard quadrature from encoders natively. There are also a number of commonly available breakout and interface boards to help for this purpose if needed.

One thought though; any feedback system using only shaft encoders is limited, as it does not give any extra benefit beyond more intelligently handling failure modes as you mentioned earlier. Under normal operating conditions they are redundant.

To actually increase accuracy or other performance attributes during normal operation, it takes MUCH more expensive linear encoders on each axis, as shaft encoders only monitor motor position. It therefore cannot reflect actual table position, as backlash or any other errors induced in the components after the motors themselves cannot be monitored by this type of system. This is as true for servos as steppers.
A shaft encoder only system has uses, not to knock them, just to point out that not all feedback systems are equal!

In terms of crash recovery, won't an accurate homing procedure do as much to salvage the job as a servo drive? You can return to a known position, fix the cause of the crash, and restart the job from there. OK, maybe a *little* more manual intervention but you'll presumably be in there anyway to fix the code that crashe dyou in the first place. And if the crash has caused the part to shift (or more likely run it over) then you're well and @#$!ed no matter what kind of drive you're using...

In terms of crash recovery, won't an accurate homing procedure do as much to salvage the job as a servo drive? You can return to a known position, fix the cause of the crash, and restart the job from there. OK, maybe a *little* more manual intervention but you'll presumably be in there anyway to fix the code that crashe dyou in the first place. And if the crash has caused the part to shift (or more likely run it over) then you're well and @#$!ed no matter what kind of drive you're using...

Exactly this. Well said.

I want ballscrews, that's easy as the CNC fusion kit has that covered.

I have the CNCFusion ballscrew kit. The X and Y parts are just fine; I'd buy them again without a second thought. Since I plan on setting up a second X2 if things go well, that's not an idle comment.

Unfortunately, the Z-axis bracketry sucks decomposing roadkill. It's nicely made and bolts right up (requires drilling a couple of extra holes in the column, no big deal). However, it covers the Z gib screws. You can't even remove the bracket without removing the head first, so any adjustment of the gibs requires completely removing the head and CNCFusion bits.

I had read complaints about this while searching for comments on the kit, but I didn't really understand what people were talking about.

I have no clue why CNCFusion did things that way, but they could have pulled the screw forward a bit to clear the gib screws, or put it in the middle like some other kits, or even mounted it on the other side. My simplest solution is to make new brackets similar to the CNCFusion ones, except mounting the ballscrew on the other side.

The KDNTools Z-axis kit mounts in the middle of the headstock. The web site shows an Acme screw, but they supposedly have a ballscrew option. The CNCFusion XY bits look sturdier than the KDNTools stuff, and were cheaper; I'd use those with the KDNTools Z kit.

The Hossmachine design also uses a central leadscrew, bit Dan ran the screw up above the machine instead of down along the column. It took a while to figure out why - the table doesn't get close to the screw on the KDNTools layout - but Dan's layout with the overhead screw keeps it out of the path of coolant and swarf at the expense of making the mill a bit taller, though you would only care if you planned to enclose it.

Thanks for the advice guys.
X2CNC, excellent information about the Z screw on the CNCfusion kit. I'll most likely still get the full kit and make new mounts later like you have. Getting the machine working is going to be the first and most important step.

If I invest in some linear scales or seperate encoders, are there any advantages to servos over steppers?

I haven't made my brackets yet, but I'll post a drawing when I'm done. I think I can flip the CNCFusion bracket around to the other side and get away with one adapter at the top of the column.

I asked about encoders a few weeks ago. There were several replies, all to the effect that they shouldn't be necessary with steppers. The count should always reflect the position as long as you're not losing steps, and if you are losing steps, you have a problem you need to fix.

If I invest in some linear scales or seperate encoders, are there any advantages to servos over steppers?

That tends to get you into a quality of gear well beyond anything reasonable for a hobbyist, while as rotary encoders can cost $20-30 each, proper linear encoders easily exceed the cost of the entire machine - for EACH one of them. They normally aren't found except on very serious five- and six-figure equipment.
That being said, there are people here who have quite creatively made some reasonably functional ones by mounting cheap Chinese digital hand calipers to each axis and wired the readouts to a custom board that converts the signals into standard quadrature, but even that adds up to quite a bit of a project and cost. I don't know who has them on here but they may pop up and offer more advice on that particular project.
Linear encoders are neat if you have them or can scrounge them up used and cheap, but really probably not the direction you need to realistically plan to go on a budget hobby mill!

If I invest in some linear scales or seperate encoders, are there any advantages to servos over steppers?

That tends to get you into a quality of gear well beyond anything reasonable for a hobbyist, while as rotary encoders can cost $20-30 each, proper linear encoders easily exceed the cost of the entire machine - for EACH one of them. They normally aren't found except on very serious five- and six-figure equipment.
That being said, there are people here who have quite creatively made some reasonably functional ones by mounting cheap Chinese digital hand calipers to each axis and wired the readouts to a custom board that converts the signals into standard quadrature, but even that adds up to quite a bit of a project and cost. I don't know who has them on here but they may pop up and offer more advice on that particular project.
Linear encoders are neat if you have them or can scrounge them up used and cheap, but really probably not the direction you need to realistically plan to go on a budget hobby mill!

I'm still throwing around ideas at this stage.
The cheap digital vernier type slides that you're talking about would work great for incremental position, but if I went to seperate encoders I'd be looking for absolute position. I've used linear potentiometers for a few projects before and still have two in the 125mm stroke size. That'd take care of the x axis, I don't know if they're available in the size required for y and z but the cost would probably be a few hundred $US for each axis.
I've spent a lot of time around serious sized cnc mills, even helped repair them but unfortunately never operated one. Some of them were large enough to mill half a car.

So it appears steppers are the most attractive option at this stage, what is the best bet for controllers and interface boards? Keeping in mind that I'd like to drive it all from a laptop via USB even though parallel and serial are available. Our power here is 240v but building/buying a power supply shouldn't be a problem.

Keeping in mind that I'd like to drive it all from a laptop via USB even though parallel and serial are available.

hrrrm? Why would you want to do that? USB was not designed for real-time functions, and is not suited to it at all. It is good for massive data transfer to 'smart' devices capable of then parsing things and data handling at their end, but CNC machines aren't smart devices. The parallel was designed specifically for direct CNC machine control, its actually precisely why it exists.
Parallel is the right tool for that job. People think it is old and therefore must be obsolete, but for this purpose there is none better - back when it was invented the old line printers that it was designed for had no buffers or internal control systems themselves, they required full direct real-time hands-on control by the host computer. Quite literally they were CNC devices, direct machine control is actually exactly what parallel was doing all along. We just happen to be the only people still using it as it was intended!

USB and parallel were developed for two different jobs, (massive non-synchronous data transfer versus real time control) and they don't interchange.

There are USB control systems for CNC out there, but they don't act like you may think. Using one, your computer isn't then the controller anymore. At that point it simply uses the USB to pass the gcode to a separate embedded controlling computer module mounted in your drive box that then does the work of sending the signals to the drivers - using, um, parallel. There is no way of getting around it, and so if you have parallel already, adding extra hardware and an extra control computer in between seems redundant.

steppers, is it possible to put encoders for feeback on them as well?
Or would this require a controller that isn't commonly available?


http://www.microproto.com/MMDSLS.htm

Not sure if something like this can easily be done strictly on the software side of things.
If the software attempts to make up for a lost step by speeding up the stepper the game is lost.
If the software can adapt the feedrate with a lost step it could work in a sort of kind of way.
If the software would stop all motion when detecting a lost step the work could be salvaged and adjustments made to the program.

Just talking hypothetically. I never gave it much thought until you asked.

Re using a digital caliper or similar for feedback. There may be a speed issue involved. Seem to remember reading something about that.

edit/ if the software could somehow add some needed steps it would be a cool solution.

There is one guy on here who is working on a motion controller that uses feedback from cheap chinese linear scales, but they only have a 50hz update rate, so that will turn out to be a problem. A better sollution would be to use them as possition checkers and not drive the motors out from the signal you get from them. Just to verify the position.

I have been working on a simple device to check for lost steps and stop the machine if it detects any. Most people say that this is overkill, but I say you can never be to safe.

Stepper Monkey is right about USB for cnc. It is used as a serial data line, not as a means to control the machine. You need some logic computer in between which converts the signal into a parallel signal.

SmoothStepper USB Motion Control Interface for Mach 3 (http://www.warp9td.com/index.php?option=com_frontpage&Itemid=1).
They just got a new shipment of 136 boards in July 14th.
No need for a parallel port at all if you are really wanting to use a laptop.
Very impressive results as you can see in the video,
he tripled his speed vs the LPT port.
This is my first test of the Beta version of Smooth Stepper. Compared the LPT port I have increased rapids from 370 IPM to 1,100 IPM. And increased the rate of acceleration by 5X... These parts are being cut @ 150 IPM.
There are other vids too using mills and steppers, just search youtube.
Something to consider when the time comes, or not.
I might have to get on the list.
Hoss

Smooth Stepper USB Interface

Yup, thats one of them. It has the embedded computer on the board to sit between your laptops USB and the stepper drives, and its job is to convert the signal into a parallel signal for real time control. For only one extra piece of gear, a couple of extra cables, and $155 bucks, you can do exactly what you could have done by simply plugging it into your parallel port in the first place, only with less performance.
If your laptop doesn't have a parallel, a PCMCIA parallel card works better and is much cheaper.

This system may indeed allow faster rapids on routers, though pointless on a mill with less than a foot of axis travel, and at the cost of giving up things like the look ahead buffers and CV, and therefore things like actual cutting time and tool life along with a lot of other nice features that are pretty important. Looks like a solution in search of a problem to me.

I can see the uses of these for a number of reasons in some cases, none that apply to this case though. You are actually giving up a LOT in exchange when you trade both your computers power and the very powerful Mach software for a simple embedded control chip and whatever limited software and memory it has available.
Rapids aren't an issue anyway here, as the mill and the motors are the limit. The LPT and Mach can send signals a LOT faster than the mill can move, so signal transfer rate through the parallel is not the short link in the chain by a long shot. Giving up a lot of useful features to fix a problem that isn't one doesn't help anything.
Get a 10' router with a fast screw and it might well be a different story.

PCMCIA cards are not that much cheaper. Unless I'm missing something? Last time I checked, a true PCMCIA parallel port cost $125. Do you know of any cheaper cards? Not the ones that are actually a usb port with a built in parallel port emulator. Those are no good when it comes to motion control.

Are ya done? 2 edits and counting:rolleyes:

Dougal,
Just giving you an option that's available out there,
If you have an open mind you can decide for yourself.
They are a new company but reading their initial pdf,
the spindle control and more inputs/outputs than 2 parallel ports
looks inviting. I've already used all of mine, an MPG hogs a bunch.
I would need to see the final PDF with the wiring diagrams and such first.
Don't just take my word, read up on things yourself
so you can make an informed decision.
There are many more options available to you.
If you want to reach me for anything, you can contact me on my website (http://www.hossmachine.info)
and I'll be glad to help.
I have shared lots of tips, tutorials and projects free for the asking.
Cheers, Hoss

Are ya done? 2 edits and counting

I like to make sure I get the point across clearly and succinctly. More productive than, say, having to use half a dozen other aliases to simply insult people with, barack.

BTW, you've done two posts IN A ROW even without threats or personal attacks, one of which even had useful information in it. Are you feeling OK Dan?

Yeah you know my name because I'm not a troll hiding behind a keyboard.
Thanks for visiting my website, hope you found it helpful.
Who might you be?
Care to share a little personal info with the rest of us?
There's no reason to hide, you're among friends:D
You should start a webpage and share some of your creations, you seem savvy enough.
It's great for business which a lot of us on here are venturing into with our hobby.
A nice little extra change in the pocket and having fun doing it.
Come on now, join in the fun, share something you designed or made,
it's almost 500 posts now with nothing.
Time to give something back, it's easy. You'll feel better.
And what happened then? Well, in Whoville they say that the Grinch's small heart grew three sizes that day.

"Keeping in mind that I'd like to drive it all from a laptop via USB even though parallel and serial are available"



You might want to keep your eye out on this thread. http://www.cnczone.com/forums/showthread.php?t=59763

And here is the website. www.cncbrain.com I cannot vouch for them but their response to peoples questions is great. Not only that but for extreme accuracy could be within the grasp of a hobbiest.

CNCBrain does look quite nice. Will have to look into that tomorrow. I had to spend over $200 to get all the outputs and inputs that I needed for my machine. So if you need lots of inputs/outputs then the USB sollution might be best, but if you are just planning on running the machine without any added functions, a simple parallel port would do just fine. I too am curious as to why you have reached that conclusion.

So much help to work through.:)

The main reason for using USB is futureproofing. Currently I have laptops with parallel ports but if/when the smoke escapes from them the chances of getting another aren't great. I have used USB-serial converters for real time control of other automation gear (servo pneumatics etc) and I can't see why a USB-parallel converter would suffer from such issues. Either way I'm willing to find out. The converters while not being a complete standalone computer are smart enough to relay data in real time.
The second reason is convenience, being able to run all the peripherals through a USB hub so having minimal stuff to unplug to remove the laptop to somewhere safe and clean when it's not being used. I don't yet have a dedicated and well setup area for my new mill.

I have a electrical mate who thinks he may be able to cook up a complete solution for me, but I'm keeping up the research in the mean time.

Hoss, thanks for chiming in. I've flicked through many of your threads but you're about 3 years ahead of me right now. The smoothstepper looks promising.
So it takes the place of any breakout boards and still requires stepper motor drivers to interface to the motors themselves?

I take it the CNC brain devices performs the same function as the 9 pin connectors couldn't provide the amperage that a stepper motor would draw? Or can they?

As for using a seperate encoder and how to modify the signal, it's done in exactly the same way as a normal negative feedback system. You track the intended position, the actual position and calculate the error between them. The range of gains (proportional, integral, derivative) determine what happens next.
That part I've done plenty on, you can imagine how spongey servo-pneumatics are for positioning and how "active" a controller needs to be to get them to accelerate, move and decelerate smoothly with changing loads.

After a little more hunting, the CNC Brain appears to be just the ticket.

So how about motor sizing (torque requirements) and motor controllers?
I'll be using ballscrews, mostly cutting alumin(i)um (yes English spelling) and plain carbon steel with some stainless steel and grade 12.9 capscrews being the hardest stuff I expect to cut. I'll be expecting to go slower with harder materials and will be bracing the machine at some stage.

I have been working on a simple device to check for lost steps and stop the machine if it detects any. Most people say that this is overkill, but I say you can never be to safe.

Overkill ? Sounds very sensible. There's an emc user doing exactly this
http://wiki.linuxcnc.org/cgi-bin/emcinfo.pl?Steppers_With_Encoders

Looks nice. Thats exactly what I'm doing right now, but I'm running TCNC, so there will be a micro controller in between for signal handeling.

USB for cnc machines will work if there is some sort of computer in between that can turn the serial signal into a parallel one and get the timing right.

After a little more hunting, the CNC Brain appears to be just the ticket.

So how about motor sizing (torque requirements) and motor controllers?


Seeing as I may have taken the thread a bit OT here's a small bump and repeat. Sorry, it's just that Blight's idea looks practical for my system.

Seeing as you're ready to spend $500 on the cncbrainz, why not go with Gecko's? Mariss Freemanis (sp?) has some very good posts on choosing motors, power supplies, etc.

Most benchtop people are using Mach3, emc, TCNC, etc. You're going into unchartered waters for most of us. If you get this going a lot of people will be seeking your advice :)

As for using a seperate encoder and how to modify the signal, it's done in exactly the same way as a normal negative feedback system. You track the intended position, the actual position and calculate the error between them. The range of gains (proportional, integral, derivative) determine what happens next.


"what happens next" being the key ingredient ;)

EDIT/ There is also talk of using ethernet with the cncbrain. Usb may not be the best option for the future.

Seeing as you're ready to spend $500 on the cncbrainz, why not go with Gecko's? Mariss Freemanis (sp?) has some very good posts on choosing motors, power supplies, etc.

In theory the CNC Brain is a true closed-loop system with position feedback from table position--in theory one that might be able to compensate for some number of mechanical flaws. In theory, because no one has seen or used one of these magic boxes yet. The Gecko drives are just drives, but OTOH, they actually exist.

That said, IF the Brain lives up to its billing, it might well open new doors for high-quality DIY CNC. Who cares about backlash or lead error in the screws if the drive can compensate for it? Precision silicon is a lot cheaper than precision steel. One can't always substitute for the other but it will be interesting to see what happens with this new gizmo, if it ever actually materializes.

Looking back to the first post - the OP mentions probing for reverse engineering.

I recall that Turbo CNC had a crude way to do this, But EMC has ongoing developement in this area.

Just another reason you may want to keep the servo plan.

In theory the CNC Brain is a true closed-loop system with position feedback from table position--in theory one that might be able to compensate for some number of mechanical flaws. In theory, because no one has seen or used one of these magic boxes yet. The Gecko drives are just drives, but OTOH, they actually exist.

:eek: But they've had a checkout available for over a month ??!! Anyone here waiting for delivery ? The vendor seems plenty sincere. Then again so did Dwayne Harlow. Not sounding the alarm bell, just suggesting due diligence before hitting the pay button.

Seeing as you're ready to spend $500 on the cncbrainz, why not go with Gecko's? Mariss Freemanis (sp?) has some very good posts on choosing motors, power supplies, etc.

They're two completely different components, the CNCbrain is an interface which offers up to two feedback channels per axis (full closed loop control), the gecko drives are just motor drives, the CNCbrain still needs motor drives but I can probably economise there now.

I tried to order the CNCbrain but their website needed tweaked to deal with shipping to foreign countries, hopefully tomorrow I can place the order.



Most benchtop people are using Mach3, emc, TCNC, etc. You're going into unchartered waters for most of us. If you get this going a lot of people will be seeking your advice :)

"what happens next" being the key ingredient ;)

EDIT/ There is also talk of using ethernet with the cncbrain. Usb may not be the best option for the future.

It will be interesting, I just feel like open loop control (steppers with no feedback) is a major handicap, the cncbrain isn't cheap, but will only be about 20% of the total cost (including mill, clamps, collet chucks etc) and should offer benefits far beyond the 20%.

Ethernet seems best when distances are large (USB can run about 5 meters before needing a booster), the USB will be fine for my plans. USB is also faster than all but gigabit ethernet.

Looking back to the first post - the OP mentions probing for reverse engineering.

I recall that Turbo CNC had a crude way to do this, But EMC has ongoing developement in this area.

Just another reason you may want to keep the servo plan.

Who/what are EMC?

These guys have a probe setup:
http://www.cadcamcadcam.com/index.asp?PageAction=VIEWCATS&Category=14

But they haven't answered my emails.

Ah, OK, I thought the CNC Brain was a complete drive system, not just a controller.

If anything, it would seem to me that with a system like that, there's very little reason to use servos. While they have some benefits as you scale up towards larger motor sizes or speeds, for this application a properly-sized stepper should work without incident, and the CNC Brain should detect and compensate for incidents more effectively anyway.

Ah, OK, I thought the CNC Brain was a complete drive system, not just a controller.

If anything, it would seem to me that with a system like that, there's very little reason to use servos. While they have some benefits as you scale up towards larger motor sizes or speeds, for this application a properly-sized stepper should work without incident, and the CNC Brain should detect and compensate for incidents more effectively anyway.

That's what I'm currently debating, I'm still hoping to get some recommendations on the torque requirements for each axis. They'll all be CNCfusion ballscrews which are direct drive.

Who/what are EMC?

These guys have a probe setup:
http://www.cadcamcadcam.com/index.asp?PageAction=VIEWCATS&Category=14

But they haven't answered my emails.

EMC2 = Enhanced Machine Controller (http://www.linuxcnc.org/) v2

Some good reading on the EMC2 Wiki (http://wiki.linuxcnc.org/cgi-bin/emcinfo.pl) - But like most rapidly advancing software much of the documentation lags behind. However you can reach many of the developers Live and in real time (pun intended) on the #emc channel on freenode.net someone is usually there 24/7 since this truely is a world wide effort and user base.

Yes its fully open source and FREE. :)

I'm probably going to use 425oz motors (probably Keling) on my X2. I am using ballscrews as well but based on Hoss's design so it's direct-drive on XY and a 2:1 reduction on the Z. IIRC the Xylotex 270oz kits were pretty popular with the CNCFusion kit and seemed to work well.

In this case the 425s only cost a few bucks more and are still in the 3A range so they should work with inexpensive drives. I've been using a HobbyCNC unipolar drive but just caught a good deal on a third IM 483 driver so I expect to use those for this project.

I wrote
Seeing as you're ready to spend $500 on the cncbrainz, why not go with Gecko's? Mariss Freemanis (sp?) has some very good posts on choosing motors, power supplies, etc.


Meaning Gecko might work well with the cncbrain. I was aware the brain claims to interpret gcode and generates the neede signals , making it the control(ler) afaict. Think it's time to quit while I'm behind :)

They're two completely different components, the CNCbrain is an interface which offers up to two feedback channels per axis (full closed loop control), the gecko drives are just motor drives, the CNCbrain still needs motor drives but I can probably economise there now.


skullworks suggestion to look at emc with servos is well worth a look.

I'm probably going to use 425oz motors (probably Keling) on my X2. I am using ballscrews as well but based on Hoss's design so it's direct-drive on XY and a 2:1 reduction on the Z. IIRC the Xylotex 270oz kits were pretty popular with the CNCFusion kit and seemed to work well.

In this case the 425s only cost a few bucks more and are still in the 3A range so they should work with inexpensive drives. I've been using a HobbyCNC unipolar drive but just caught a good deal on a third IM 483 driver so I expect to use those for this project.

Thanks for the torque ranges. Sounds like anyting in the 300 ozin range will do the job.
Are the 425's still the NEMA23 frame size?

I've ordered the CNCfusion kit, still waiting to hear confirmation on the CNC brain order.

Next set of questions.
Zero backlash couplers, where is the best place to find them? They're not difficult to make but if I can buy them for a good price there's no need to make them.
Brakes for the Z axis stepper, where is the best place for those?

My 2 cents:
Hi guys, hopefully some of you can spare some knowledge to help a newbie.

I'm in New Zealand and have bought a mill that while rebranded, having an MT3 spindle and running on 240v is essentially an X2. So to save confusion I'll call it an X2 from now on.

I want ballscrews, that's easy as the CNC fusion kit has that covered.
I'm on the fence regarding servos vs steppers. The absolute positioning of the servos will be a major advantage (I freely admit to crashing and stalling machine tools) and I like that I can buy braked servos which will go nowhere when the power is off.
I have the CNC Fusion ballscrew kit. can you backdrive the axis when the steppers are off ... yes, but it's not as easy as you are thinking. My Z is held perfectly in position and while it's easier to turn the stepper (I have a knob I can put on the dual shaft) to go down, it doesn't fall on it's own weight.

I have absolutely no idea what control system to buy and I need help here. I would like to run the system from a laptop and will probably have to build/buy a 24v supply. But I would like the rest to be as complete for plug and play as possible.
I run mine from an old Pentium 3 733MHz Dell laptop. I'm using the HobbyCNC Pro board with a 28V linear P/S I built. More voltage means your stepper coils can charge quicker ... but the faster you spin a stepper the less torque it has. 24V is fine. I use Mach3 I bought when I got my steppers from Kelinginc.net
I'm fairly savvy with electronics, but I'd rather pay for a kit to avoid the hassle.
Unfortunately, the HobbyCNC doesn't ship international (this may have changed so confirm) but there are some other kits to consider. http://pminmo.com/ has a long list.

CAM is something I'll address later. I've been playing around with demos of lazycam as well as cambam and g-simple thanks to finding out about them here. I'm a solidworks user, I have used G-code for industrial automation but not milling and have never used a CAM package before. But I know plenty of people who earn their living that way.

Any help appreciated.
CAM BAM ... great little program. Still a work in progress but I have found it very useful. Lazy CAM - I haven't played too much with it, but I didn't get very far trying to intuit how to use it :) Vectric.com Cut 2D ... I'm weighing this against the CAM BAM. Right now I'm playing int he PCB arena so it's not a priority but I like the Vectric about 25% more.

Hope this helps,
Jay

My 2 cents:

I have the CNC Fusion ballscrew kit. can you backdrive the axis when the steppers are off ... yes, but it's not as easy as you are thinking. My Z is held perfectly in position and while it's easier to turn the stepper (I have a knob I can put on the dual shaft) to go down, it doesn't fall on it's own weight.

I run mine from an old Pentium 3 733MHz Dell laptop. I'm using the HobbyCNC Pro board with a 28V linear P/S I built. More voltage means your stepper coils can charge quicker ... but the faster you spin a stepper the less torque it has. 24V is fine. I use Mach3 I bought when I got my steppers from Kelinginc.net

Unfortunately, the HobbyCNC doesn't ship international (this may have changed so confirm) but there are some other kits to consider. http://pminmo.com/ has a long list.

CAM BAM ... great little program. Still a work in progress but I have found it very useful. Lazy CAM - I haven't played too much with it, but I didn't get very far trying to intuit how to use it :) Vectric.com Cut 2D ... I'm weighing this against the CAM BAM. Right now I'm playing int he PCB arena so it's not a priority but I like the Vectric about 25% more.

Hope this helps,
Jay

Yes that does help, thanks.

Are you using the same size steppers on each axis? I'm wondering if the Z needs more torque for drilling steel?
The pminmo link is a handy one.

What are you using your mill for and what materials do you cut other than PCB boards?

Just an update.

My CNC Fusion ballscrew kit has arrived. CNC Brain is shipping, still haven't found motors, looking for dual shaft Nema 23 frame, around 300 oz-in (2Nm).

www.kelinginc.net

Good to see another kiwi! That makes about 4 of us... We're taking over :)

Would you happen to know what class ballscrews the CNC fusion ones are, and how the premium ones differ?

Looking forward to hearing how the CNCbrain goes for you too - I'm using the smoothstepper & brushless servos, but the brain looks very interesting.

Regards,

Jason

Good to see another kiwi! That makes about 4 of us... We're taking over :)

Would you happen to know what class ballscrews the CNC fusion ones are, and how the premium ones differ?

Looking forward to hearing how the CNCbrain goes for you too - I'm using the smoothstepper & brushless servos, but the brain looks very interesting.

Regards,

Jason

Now there are four of us, but there are about four more who'll probably jump once I've got mine working.:)
Were you selling some hobby CNC parts on trademe a few weeks back? I figure the sector here is small enough that sooner or later I'll run into whoever it was.
The CNCfusion ballscrews are rolled, not ground (this was expected). I worked for an automation company so I know the sharp price premium to ground screws.
But I don't know what grade finish or tolerance these are made to.

Where did you get your servos from and what size are they? I still haven't made the servo/stepper call yet and if I find the right servo setup I could still jump in that direction.
Are you using an X2 type mill? Direct drive onto your ballscrews or geared down?

I want some absolute linear scales to get feedback on the x and y when I'm up and running. The brain has provisions for up to two feedback devices per axis, so as well as tracking your motor position you can track errors in your ballscrews as well as backlash in the couplers.

Yes, it likely was me selling parts on Trademe - I need the space they're occupying :) I spoke to a gentleman today who happened to be another one of us too - quite a coincidence.

I bought my servos from the US - some from Ebay, and quite a few sets from a nice chap somewhere near Alabama. He's run out, but I'm awash with them now... Mostly NEMA23, with 8000 CPR encoders, peak torque about 3.8Nm. I built my machines (that's one by my username), but I think the travels on the small ones are similar to the X2... or I might be thinking of the X3? Not sure - about 400 x 170 x 170 mm. I'd really like to produce them when I have my company set up and workshop built. The 'prototypes' are looking quite good, I think. They're intended for small HF spindles, mould work, jewellery & prototyping, that sort of thing.

Direct drive ballscrews best fitted my design so that's what it is. Actually, I made a bigger machine (550 x 410 x 410 travels) with 10mm pitch ballscrews that is direct drive too, and even with the coarse pitch it has enough power to snap 1/4" carbide end mills easily.

You'll be super accurate with linear encoder feedback - there can't be many who have gone to those lengths with an X2, surely? I look forward to hearing how that goes.

Keep us posted!

Best regards,

Jason

Ps, if you're going for linear encoders, surely you should be using linear motors? Hey, I have one for sale ...what a coincidence! :rolleyes:

Another update, the CNC Brain has arrived.:)

So thanks to your thread, I went and checked on the CNC Brain. Very intriguing device, but I'm wondering about a few items. If you run it open loop what do you gain? To run close loop you need linear encoders on the axis. Where to put them, and how to mount them? The double closed loop seems easy after to get past the LE's as long as you have DS steppers. Looking forward to how you proceed.

Jay

Yes that does help, thanks.

Are you using the same size steppers on each axis? I'm wondering if the Z needs more torque for drilling steel?
The pminmo link is a handy one.

What are you using your mill for and what materials do you cut other than PCB boards?

Sorry I missed this post. Yes, I am using the same sized stepper on all three axis. I haven't tried and steel, but here is a recent vid (http://www.cnczone.com/forums/showthread.php?t=62858) of aluminum. I learned a lot from that experience so the next parts will only get better.

BTW, I decided on Vectric Cut2D for my needs. The price is right and the SW is perfect for my needs.

FWIW,
Jay

So thanks to your thread, I went and checked on the CNC Brain. Very intriguing device, but I'm wondering about a few items. If you run it open loop what do you gain? To run close loop you need linear encoders on the axis. Where to put them, and how to mount them? The double closed loop seems easy after to get past the LE's as long as you have DS steppers. Looking forward to how you proceed.

Jay

If you run it open loop there's probably not that much benefit other than having a USB connection, very neat packaging and a nice user interface. But running closed loop (as all control should IMO) the benefits will all be there.
You can run either linear encoders or rotary or both as I understand. Rotary encoders won't pick up backlash but they will know when your motors are struggling to keep up and can head off potential errors.

I'll be getting dual shaft motors anyway and probably start with rotary encoders. Linear scales aren't the price shock I was expecting but they can wait. The Brain also has inputs for both a touch probe (use your mill as a CMM) and a touch pad (automatic tool length adjustment).

I still haven't used it with my mill, but now I've got it connected to the computer and installed it's looking very promising.:)

What's the price difference between rotary and linear encoders? I've always felt that rotary encoders on mills this size are kind of an extravagance, but the concept of what the CNC Brain can do with linear encoders might offer much higher precision for less $$ than needed for high-quality ballscrews and all that.

What's the price difference between rotary and linear encoders? I've always felt that rotary encoders on mills this size are kind of an extravagance, but the concept of what the CNC Brain can do with linear encoders might offer much higher precision for less $$ than needed for high-quality ballscrews and all that.

It looks like rotary encoders are about $30 each and linear around $150 each.

That sounds pretty cheap for the linear encoders - can you tell us where that's from and what resolution they are?

Thanks,

Jason

That sounds pretty cheap for the linear encoders - can you tell us where that's from and what resolution they are?

Thanks,

Jason

Here's the thread I found them on.
http://www.safeguardrobotics.com/forum/forum_posts.asp?TID=24

Motors ordered. 280 oz-in dual shaft steppers.

Hopefully Gecko will release their new controllers soon, no-one likes buying yesterdays technology.

I ordered my controllers today.

Gecko have their new G250 drives for the frankly ludicrous price of $US30 each.:)

So I bought four in case I blow one up. If I don't blow one up I'll add a fourth axis at a later date.

Thanks for the link for the encoders - I see a couple of the places referred to in that thread offer 1 micron resolution as an option. Almost fine enough for a linear motor... I feel a new machine coming on :)

Hey, if you don't blow up the fourth stepper driver you'll have to add a rotary axis to use it up :) EDIT - (Doh...)

Don't forget to show us a photo of all the parts laid out ready to go!

Best regards,

Jason

Thanks for the link for the encoders - I see a couple of the places referred to in that thread offer 1 micron resolution as an option. Almost fine enough for a linear motor... I feel a new machine coming on :)

Hey, if you don't blow up the fourth stepper driver you'll have to add a rotary axis to use it up :) EDIT - (Doh...)

Don't forget to show us a photo of all the parts laid out ready to go!

Best regards,

Jason

Come to think of it, a linear motor would be ideal for a shock dyno. Hmmmmm.

Yes a rotary table is in the plans, but for now the budget is hurting enough already. At least I saved some coin on the motors and drivers.

Geckos arrived.
Microswitches bought.

Almost time to bolt everything together.:)

Just need a power supply and a lot of cords. Heading towards 50v and 4 amp power supply and 6 DB9 plugs with leads.