Usb smooth stepper

[Tumblebeer]

No this isn't a good idea. While in theory and practice it does works it gives problems due to the way drives work regards handling midband resonance. Modern drives compensate for mid band resonance and apply correction, problem is the correction only happens on one motor but at same time forces the other motor into resonance so it's a bad idea and often results in lost steps and crazy weird shit happening. (If 2 motors sharing one drive)
Also then there's slight timing differences and if your lucky enough to run the motors in range where you avoid resonance the timings can slowly run the machine into loosing positon and racking etc.!

I'm not saying to connect two motors to one driver, but rather connect two drivers to one step output. The aim of a slaved axis would be to provide two identical step pulses anyway, yes? There's no feedback from the driver to the controller anyway, so it can't possibly adjust more synchronized with separate step pulses than with two parallelled identical?

[JAZZCNC]

I'm not saying to connect two motors to one driver, but rather connect two drivers to one step output. The aim of a slaved axis would be to provide two identical step pulses anyway, yes? There's no feedback from the driver to the controller anyway, so it can't possibly adjust more synchronized with separate step pulses than with two parallelled identical?

I know what your saying but the answer is not simple and several factors play apart. The BOB output circuitry plays a hige part and like wise so does the drive input circuitry. Often output signals are buffered and filtered on the BOB and only have a certain amount of current available and if the drives are optoisolated which often they are there may not be enough current to drive both opto's correctly and then signals start going stray. This is just a simple version and there's more to it than this but the up shot is your playing with fire and likely prone to timing errors.

IMO why bother to go to all the trouble and time building the machine only to spoil and cripple it for the sake of a few more pounds.?

[vre]

Real stuff are real time linux kernel + linuxcnc + mesa fpga or any other card that supports real time.
If you want industrial level controller with low cost that is the way.
USB is not a real time interface all usb boards use buffers mach3 is not real time because windows is not real time.

[Ger21]

I've been using "industrial" machines that cost $150,000 or more for almost 20 years. They all run from a Windows PC.
I doubt that there are any real commercially available "industrial " machines running Linux CNC.

LinuxCNC is a viable alternative. But the LinuxCNC guys need to stop knocking Mach3 every chance they get.
Mach3 users probably outnumber LinuxCNC users by at least 20:1. So Mach3 can't be all that bad.

[vre]

I have seen an industrial machine 160k euros or 216k usd it is semi-realtime because it has a realtime fanuc motion controller (with buffer)
but it don't show in real time at windows program what the machine is doing, is realtime but it has no realtime feedback to windows (windows is not realtime).
The only realtime part that machine have is the fanuc controller not the windows software...

Linuxcnc is not alternative.. is the only way to get a soft real time industrial controller with low cost.
I dont want to knock mach3 but the difference with linuxcnc is huge (difference to the underlying os) that is the simple truth.
The problem is not in mach3 is to the windows which is not real time os.In the other side linux has a realtime kernel.
You can get realtime with mach3 but only with a hardware realtime motion controller and buffer.
Caveat with linuxcnc is more difficult learning curve.

[dazza]

Any feedback on this below,theres not that much chat about em on the web...,im not sure how long they've been around.

http://cncdrive.com/UC300.html

[JAZZCNC]

Any feedback on this below,theres not that much chat about em on the web...,im not sure how long they've been around.

http://cncdrive.com/UC300.html

Don't know anything about these UC300 but do know plenty about other USB based motion control cards SS USBCNC etc and I would advise you to go with Ethernet based cards as they are much better regards handling noise which plagues USB cards. They also allow much longer cable runs and can be connected to networks etc. They appear to give a cleaner signal as well which translates into faster smoother motion.

My Favorite (and I have most common cards) by a very long margins is the CSLABS CSMIO-IP-M or IP-S and while the IP-S is expensive nothing comes remotely close in it's class.

[magicniner]

The problem is not in mach3 is to the windows which is not real time os.In the other side linux has a realtime kernel.
You can get realtime with mach3 but only with a hardware realtime motion controller and buffer.
Caveat with linuxcnc is more difficult learning curve.

I think there are a lot of guys out there milling and turning parts who have a problem they don't know about, how about you don't tell them and they'll just keep making the parts ;-)

- Nick