Thread: Usb smooth stepper
I've seen people connecting step and dir of both x axis motor drivers to the same output on a bob. It's there some reason this isn't a good idea? If the IP-M can source/sink enough current this would work to slave, yes?
Last edited by Tumblebeer; 12-07-2014 at 09:49 PM.
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.!
Last edited by JAZZCNC; 12-07-2014 at 10:42 PM.
Some experience from my build.
If you make your long rails perfectly parallel / using some hard stop fixture and precise square and rule or straight edge/ and perfectly level -using epoxy, then will be very easy to align perfectly the ball screws. That would lead to extremely precise movement where the only factor left would be a missed step due to who the hell knows what reason.
So doing all this correctly will lead to such ease of movement, as i discovered some days ago, that the gantry will move without racking even with one motor only and the other tripped. The tripped motor ball screw will turn by itself even with speeds like 10m per minute as i said-without racking.
What i want to say is not worry, if you like the controller, wire it like Dean says, you can use hard stops to Zero the gantry axis at some very low speed / this programmed at the soft limits tab in mach3/
Another thing is that the Leadshine stall detect works better than expected/ found with faulty LPT cable/ so if you wire the alarm to say Enable or something similar or alarm input/ the machine will stop right away. Then take the power of the motors, move screws by hand so to say to center more or less the gantry, then run again and Zero.
This is a worse case scenario which may happen very rarely if ever when the machine is tuned.
Anyways, doing the machine precise is a must and so is centering the ball screws. Otherwise there will be problems later. Like running out of square/the gantry and the job, cause the travel of rails differs between them/due to slight angle out of parallel/ or between rail and screw/for the same reason as before said/, and that means adjusting steps in Mach separately for the gantry motors, which i believe could be a nightmare, especially if you aim precision.
As to the Americans and their preferred drives and BOBs. I have Geckos on my machine and they never lost a step for 3 years, coupled with Campbel design BOB. So,for sure there is a reason why. Too bad that they are far away and we have to pay tax.
About the CSMIO 6 axis controllers. Cheap from industrial point of view. Very expensive from DIY point of view. Not worth the effort for me. On my next build which would be quite industrial i spend nights contemplating to buy or not. 549.00 EUR + 23%=667euro. Not for me. I bought 8 axis Galil for 500eur which though risque, seemed quite a better purchase with much more possibilities.
At the end it seems there is almost no choice of BOBs, though it looks at first glance that there are a lot of them.
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.?
Last edited by JAZZCNC; 13-07-2014 at 07:29 PM.
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.
Last edited by vre; 22-07-2014 at 11:32 AM.
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.
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.
Last edited by vre; 22-07-2014 at 02:05 PM.
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