Q2 - wiring. Those two circuit diagrams are effectively the same. Not sure why you would want to do B. Diagram A shows a short wire connecting two terminals on the BOB; in B you need two longer wires running to the switches. However, as I say, electrically they are equivalent.
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Wouldn't go above 10x Ms because you'll gain very little just stress the system more. Often the machine will dictate to some degree the best MS setting based on the resonance and how it affects the motors at different speeds. Again better drives will handle this better allowing optimum Ms without sacrificing anything in terms of motor smoothness/speed.
You want half current Mode On because it lowers motor heating when stood still.
Well got most of the wiring run today, and i thought I would give it a quick test with just the X-Axis hooked up to see if i could get basic communication and motor control.
Having installed the drivers and connected the UC300 to the computer successfully i thought i was home free, however i got absolutely no response in Mach from either the Estop button or the XAxis motor when jogging.
As per the BOB KK01 diagram from CNC 4 You, I have the Estop wired to pin 15 / ground.
There is 5V wired to the UC300 and the BOB, and both have power lights on.
The LPT cable is attached from UC300 to the BOB. Tried both standard ports.
Under Ports and Pins, Mach 3 knows to look for Estop on Pin15 and xaxis motor on Pins 2 / 3 (Port 1).
Have i missed something or is it possible i have a faulty BOB / uc300?
Anyone got any suggestions on how to troubleshoot this ?
Last edited by mturneruk; 19-12-2015 at 10:35 PM.
Sorted it. Was messing about in Mach 3 and i discovered that the port should of been 2 and not 1. Pure guess, but now everything works as expected. That was lucky.
Have first movements video from yesterday.
Looking good. Really pleased. My long axis seems (which i call y / a) seems to make much more noise than my short axis (which i call x).
Obviously there is two steppers running, but the noise seems a lot more. I think is could be down to the movement resonating through the table.
The noise is far more at higher speeds. So far i have only dared to go to 2000mm per minute with acceleration of 250.
What do you think those stepper motors could handle if I wasn't worried about the noise?
The anti backlash Nuts were tightened to the gantry near the end of the ball screw travel to ensure they were correctly aligned.
As you can see i have used some plastic combined with aluminium angle to make a rudimentary guard around the screws.
Onto the sensors now, which i am trying to work out how to mount.
The electronics seem to be sweet so far.
Depends on ballscrew pitch and Volts your running steppers at. But given it's relatively light weight construction ie not heavy gantry and using External motion controller then some thing like below.
If 10mm pitch and say 60-70V then you should easily velocity at 10mtr/min and would proababy max out around 14-15mtr/min. Maybe slightly less on the Y axis. With Accel of roughly 800-1000. Just remember can't have both high Vel and high Accel.
If 5mm pitch and 60-70v then roughly half the above velocity figures. With slightly less Accel.
If less volts then slightly less speed but with around 40-50V I'd only expect about 15-20% less.
How you tune the motors will depend on several factors like type of work you'll be doing etc. Good all round setup for such a small machine would be Max velocity of 8000mm/min with Accel around 1200-1500.
This is based on 10mm pitch/60-70v. It will give you good balance of speed and accel along with reliabilty.
Nice job by the way and you'll make some nice stuff with that. Well done. .
Last edited by JAZZCNC; 21-12-2015 at 07:54 PM.
I am running 1605 ball screws at 48v.
I tried last night on 4000mm per minute, and that seems just about ok actually. I tried higher, but it was screaming at me, so I tuned it down.
As far as the acceleration goes, i have increased it to 600 and that seems ok with hardly a noticeable ramp up in acceleration.
At the end of the day, i guess i will just have to play with it to find the best settings for my machine.
I don't really need it to be able to run stupid fast, but I am hoping to be able to make much deeper cuts which will be the main time saving.
I think I am going to need a way to lift my machine up off it's castors when it's in use.
I seem to be getting an amount of table movement when the machine is moving around.
Martin, its looking good...you'll love making bits with that. Will be interested to see what you plan for machine build number 2 ;)
Are you putting any sort of dust/chip extraction in? One thing I've found is that dust and chips goes everywhere and I mean everywhere!Neil...
22-12-2015 #139I think I am going to need a way to lift my machine up off it's castors when it's in use.
I seem to be getting an amount of table movement when the machine is moving around
What I do is lift the front end with a lever (bit of 3x2) and then put two blocks under the frame and I find that is OK for me.
I think your machine is much too clean and needs to be making a mess now..Clive
If I was running that setup I'd be tuning it at 4500-5000mtr/min with 800-1000s/s.
Speed you cut at is mostly determined by the material, cutter and machine ridgidty etc. It shouldn't really be based on what you feel comfortable with in terms of being afraid or scared to push machine. Your far more likely to break cutters and ruin work by under cutting than you are ever likely to break the machine.! . . . . The machine it's self will soon let you know when it's not happy.!
NOW get them switches on and make some Bloody chips. . .
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