Taig CNC Mill, round two

[RB211]

Ok, I called Taig this morning and found out some things...

The ball screw taig CNC comes with everything except for a computer for 2995. Another 125 for the USB option for Mach3. So a little over 3k.

The ball screw CR model which doesn't include steppers or motion is 1850.
300 for the Acorn, 300 for a G540 and 48v power supply, and another 60 for steppers, you are around 2500$. Going with import stepper drivers can further lower that price.

Left out the cost of a computer because that's an afterthought.
Nick Carter offers 10% discount, for further price savings.

3phase, I am leaning heavily towards the Acorn route

[3 Phase Lightbulb]

Is this a 2-axis, or 3-axis, and is there support for adding a 4th-axis for a rotary or indexer? The 4th axis is just something nice to have the ability to add later of course.

Also, what kind of features are we talking about? Do either options computer controlled spindle power/control or is that typically done with manual power/speed controls for these guys. Do either options support misc outputs for things like coolant on/off, etc?

Does either/any of the options provide a manual mode (preferably with electronic e-wheels)?

What about "touching off" types of sensors for positional/origin/digitizing/etc. Do any of those systems support adding stuff like that?

I'm not listing requirements, just wondering what's typically available/used on these small CNC systems.

[Bob La Londe]

Ok, I called Taig this morning and found out some things...

The ball screw taig CNC comes with everything except for a computer for 2995. Another 125 for the USB option for Mach3. So a little over 3k.

The ball screw CR model which doesn't include steppers or motion is 1850.
300 for the Acorn, 300 for a G540 and 48v power supply, and another 60 for steppers, you are around 2500$. Going with import stepper drivers can further lower that price.

Left out the cost of a computer because that's an afterthought.
Nick Carter offers 10% discount, for further price savings.

3phase, I am leaning heavily towards the Acorn route

Its pretty well documented that USB can have latency times that cause problems. Particular if you use another USB device at the same time. They could be using a number of USB interface devices, but the UC100/UC300 and the Smoothstepper are the most common. The Smoothstepper is better designed to work with Mach 3 and implement all necessary features. It also costs more than $125 so its not likely to be the USB option they are offering. If going that route I'd go with an Ethernet Smoothstepper (which costs even more) as the ethernet connection is very reliable and subject only to actual slow downs or overloading of the computer itself. Ethernet also has built in timing and error checking in the hardware. I have four machines currently running Ethernet Smoothsteppers, and one running a USB Smoothstepper and one running a MESA IO card. I've used straight parallel and it works, but its subject to all kinds of issues. If trying to run straight parallel communications I'd definitely go LinuxCNC over Mach3.

If going with Acorn I have no feedback.

I have had two G540s fail. One was totally my fault for poor setup while I was still learning, but the other was well cooled, protected, and run within spec. Interestingly the one I abused was replaced no questions asked, but the other was refused. It was not the replacement for the first one. I no longer run any G540s, but I have one you can have for shipping. I think it will fit in a small FRB. At one time I was running three of them.

I was told that GeckoDrive has a one time free replacement no questions asked policy, but my experience show that there was no warranty on additional units purchased separately after that. Maybe it was just a misunderstanding.

[RB211]

Is this a 2-axis, or 3-axis, and is there support for adding a 4th-axis for a rotary or indexer? The 4th axis is just something nice to have the ability to add later of course.

Acorn supports much more than 4. 8? The G540 I think is 4 axis.

Also, what kind of features are we talking about? Do either options computer controlled spindle power/control or is that typically done with manual power/speed controls for these guys. Do either options support misc outputs for things like coolant on/off, etc?

Acorn supports ALL that stuff, the taig mill is a simple on/off spindle motor. You could add any motor you want to the Taig with speed control, the ACORN has 0-10vdc analog out for stuff like a VFD for variable speed control.

Does either/any of the options provide a manual mode (preferably with electronic e-wheels)?

What about "touching off" types of sensors for positional/origin/digitizing/etc. Do any of those systems support adding stuff like that?

Acorn supports all of that, even wireless pendent controls, or if an Xbox360 controller floats your boat

I'm not listing requirements, just wondering what's typically available/used on these small CNC systems.

ACORN is Centroids move into the hobby world, they make commercial controllers for the big boys, so you have all these options. Linux CNC also gives you all these options, so does Kflop, and all the others. Watching videos on Youtube, I like what the ACORN offers.

[RB211]

Its pretty well documented that USB can have latency times that cause problems. Particular if you use another USB device at the same time. They could be using a number of USB interface devices, but the UC100/UC300 and the Smoothstepper are the most common. The Smoothstepper is better designed to work with Mach 3 and implement all necessary features. It also costs more than $125 so its not likely to be the USB option they are offering. If going that route I'd go with an Ethernet Smoothstepper (which costs even more) as the ethernet connection is very reliable and subject only to actual slow downs or overloading of the computer itself. Ethernet also has built in timing and error checking in the hardware. I have four machines currently running Ethernet Smoothsteppers, and one running a USB Smoothstepper and one running a MESA IO card. I've used straight parallel and it works, but its subject to all kinds of issues. If trying to run straight parallel communications I'd definitely go LinuxCNC over Mach3.

If going with Acorn I have no feedback.

I have had two G540s fail. One was totally my fault for poor setup while I was still learning, but the other was well cooled, protected, and run within spec. Interestingly the one I abused was replaced no questions asked, but the other was refused. It was not the replacement for the first one. I no longer run any G540s, but I have one you can have for shipping. I think it will fit in a small FRB. At one time I was running three of them.

I most certainly will take you up on your offer for that G540! Thank you! The Acorn is ethernet, not usb.

[3 Phase Lightbulb]

Sounds like Acorn is what I'd like too.

[skunkworks]

Sounds like Acorn is what I'd like too.

make sure you look at what it cost with all the extra 'stuff'

sam

[3 Phase Lightbulb]

make sure you look at what it cost with all the extra 'stuff'

sam

Cost is not an issue but I would like to have the flexibility there to add stuff.

[RB211]

make sure you look at what it cost with all the extra 'stuff'

sam

Yes, the free edition of the mill software has a limit to G code size, not sure what it is. 140$ unlocks it to pro. Digitizing is another 399$, but don't have any current desires for that.

[RB211]

A cool video on ball screw mapping...

[Bob La Londe]

I don't know that this has any bearing, but a friend with an old Bridgeport with a Heidenhain controller had a system failure. He ordered a Centroid (not Acorn) complete replacement package. (quite a lot more than an Acorn controller) He said he had it running in less than 24hrs after receiving the kit, and was cutting jobs after some testing a day later. He was doing a running commentary on the CB forums at the time so it seems likely he was not exaggerating.

[skunkworks]

You had asked this in the closed thread.

Linuxcnc is the motion controller. It has to run in a realtime environment. External interface cards like mesa lowers the bar a bit for the computer. (latency can be higher - aprox 100us vs if you did printer port software step generation you would want < 20us)

Linuxcnc has the 'sense, model, act' So 1000 times a second (every ms) linuxcnc
Reads all inputs (including position feedback) (sense)
plans trajectory, ladder logic, pid, etc (model)
writes outputs including torque/velocity commands. (act)

and the 1000 times a second is settable.. (although works for most machines)

sam

You mentioned you needed realtime kernel extensions for your system? Why is that? Doesn't the ethernet based controller decouple any/all real time requirements?

Edit: Unless the host is reading scales/feedback out-of-band and latency from reading the scales would cause servo/stepper error oscillation/etc?

[Bob La Londe]

You had asked this in the closed thread.

Linuxcnc is the motion controller. It has to run in a realtime environment. External interface cards like mesa lowers the bar a bit for the computer. (latency can be higher - aprox 100us vs if you did printer port software step generation you would want < 20us)

Linuxcnc has the 'sense, model, act' So 1000 times a second (every ms) linuxcnc
Reads all inputs (including position feedback) (sense)
plans trajectory, ladder logic, pid, etc (model)
writes outputs including torque/velocity commands. (act)

and the 1000 times a second is settable.. (although works for most machines)

sam

There is an offboard Ethernet card from MESA now. Tormach is using it, although I don't know if they are using exclusively yet. My 1100 controller came with a 5i25.

[3 Phase Lightbulb]

You had asked this in the closed thread.

Linuxcnc is the motion controller. It has to run in a realtime environment. External interface cards like mesa lowers the bar a bit for the computer. (latency can be higher - aprox 100us vs if you did printer port software step generation you would want < 20us)

Linuxcnc has the 'sense, model, act' So 1000 times a second (every ms) linuxcnc
Reads all inputs (including position feedback) (sense)
plans trajectory, ladder logic, pid, etc (model)
writes outputs including torque/velocity commands. (act)

and the 1000 times a second is settable.. (although works for most machines)

sam

Ok, I thought positional information was simply sent down to the controller and the controller itself handled the movement, PID correction, etc. It sounds like the computer is doing that and the controller (that you're talking to via Ethernet) just does PWM and doesn't close the loop by itself?

[3 Phase Lightbulb]

Got a meeting. Be back in ~1 hour