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alden
MemberSince you are running 3 threaded axes you do not need the Shapeoko mod. Sorry for the confusion.
MemberHere are a few things you can try.
1. Set the trimpots in the middle of the range and leave them there. Almost every motor that grblshield is capable of driving will work in the middle of the range.
2. Try switching the motors to see if the motor has problems or the channel has problems.
3. Try running the board with no motors. Do the LED’s light when you issue Gcode commands like G0x10?
4. Check your grbl settings
5. Check your motor wiring
SOme help on these items can be found on the wiki:
http://www.synthetos.com/wiki/index.php?title=Projects:grblShieldMemberThe reason is explained on the Shapeoko forum in this post:
http://www.shapeoko.com/forum/viewtopic.php?f=4&t=221MemberGrbl makes all LEDs turn on at the same time. This is normal. Did you over-torque the potentiometers? They only turn through 270 degrees. If you try to force them they will break and the motors will not turn. If you did this may be why the motors don’t turn.
-Alden
MemberIf you are running the Shapeoko I recommend making the Z axis mod. Here is a page describing the rationale and instructions. It’s quite simple and takes about 5 minutes. If you are running another CNC machine like a Zen Toolworks or a Probotix this is not necessary.
http://www.synthetos.com/wiki/index.php?title=Z_Axis_Mod_for_ShapeokoJune 21, 2012 at 9:11 pm in reply to: Travel per Revolution set to 1mm, stepper turning only 3/4 of a turn when asked to move 1mm #2597MemberFabrice,
No worries, we’ll leave it up. These systems require tuning in many layers – the mechanical layer for the machine itself, the motors, and the settings and software.
If you have not already done so, I’d recommend reading the section on setting motor current here:
http://www.synthetos.com/wiki/index.php?title=Wiring_TinyG– Alden
MemberI still haven’t tried it, but would like to. You should be able to wire pin1 of the USB port over to the 5v input of the power connector. Perhaps through a ferrite bead. The grounds are referenced the same, so that should be OK. If I recall correctly the board consumes about 80 ma, so the 100ma limit on USB at plugin should be OK. I will need to check the current draw, wire it up, cross my fingers, and turn it on. Now that I have an idea of what to do let me see if I can get to this in the next day or so.
– Alden
MemberBrendan,
Try setting the switches to 1 instead of 2 – homing only, no limits. See what this does.
Ref: http://www.synthetos.com/wiki/index.php?title=TinyG:ConfiguringThere is no bug fix related to this issue, but can you tell me what firmware build you are running? The latest build is 338.12 / revision 0.93
-Alden
MemberI think Shapeoko is a great option, and thank Edward Ford, Bart Dring, and the rest of the community for all the hard work. I have a number of 3 axis tables, mostly commercial. Each one is better at doing something than the others, but none are as good as Shapeoko for pure flexibility and hackability. Given that it’s based on Makerslide you can pretty much turn it into anything. I have some interesting projects up my sleeve that I wouldn’t try to do on any of the other machines. It’s also quite inexpensive.
–Alden
MemberUsing belts or screw is a trade off.
Belts: Fast, inexpensive, less precise than screws, not much cutting power (if you need that – 3d printers do not)
Screws: Slower, more expensive but a lot of power and much more positional accuracy.Grbl/grblshield works fine with mixed belt/screw designs, but it does have some limitations. Grbl/grblshield has a single maximum velocity for all 3 axes. If the Z axis can’t move as fast as the X and Y the machine must be limited to the speed of he Z axis.
— Alden
MemberSorry to hear you are still having problems. Let’s re-examine the facts.
– The Z axis was not working and now it is. This makes me think that the wiring might be intermittent. Have you swapped the motors around – X on Y, etc? Results?
– All three LEDS flash when you run a command. This is good. This means the stepper drivers are working. It’s possible that Y is not putting out enough current – but it is putting out something. The LEDs do not indicate thermal cycling, they indicate that voltage is being output to the A winding. (We could have put a second LED for the B winding but in most cases this is redundant).
– Y is trying to move but can’t. Does this happen regardless of what motor you try? This sounds like the current reference from the pot is not what it should be (assuming it’s not a motor or wiring problem). Do you have a VOM and can you read the input and output voltages on the Y current setting pot? The schematics are on the grblshield github.
— Alden
MemberI like that the problem is fixed / I don’t like that it just magically just fixed itself. I’m sure you wracking your brain trying to figure out what’s different. Let me know if this recurs. The only thing I can think of that would affect all axes equally is the input reference voltage for the current setting pots. The reference voltage going into the pots is the 5v that comes off the Arduino. If that’s not stable there could be all kinds of havoc.
The chips will get that hot when you run them at close to their max. That’s just the way they are. I think you will find this on all the small stepper driver chips. This is why we offer heatsinks, and suggest fan cooling. However, with the motors you are using you should not need to run them that close to the limit to get max torque, or at least sufficient torque. So you might try backing off the current in a real application – i.e. cutting – and see if you get adequate torque.
I do not know of a command that is capable of locking an axis. What are you trying to do? I’m not sure I understand. In TinyG you can set axis modes. You can disable an axis or inhibit it. A disable takes the axis out of the calculations – i.e. removes it like it never exists. An inhibit incorporates the axis into the motion calculations but doesn’t run it. This is good for Z kill. There is no command to just freeze and axis by applying power but no motion – if that’s what you are looking for.
— Alden
MemberSorry to hear about the issue. This is not usual. Some questions:
– What version of grbl are you running and what are your grbl settings?
– What is the manufacturer and model of the stepper and do you have spec sheets or a link?
– When you are doing the test are you running one axes, 2 or all?
– Does the thermal behavior happen on all axes or is it more pronounced on any of X, Y or Z?
– Do you have a 24 volt supply available to you?
– (edited) What commands are you running through grbl for the movement = G0 X1000 Y1000 Z1000 or something like that?
– (edited) One last thing, when you turn the board over do you see solder in the 0.080″ holes under the chips?Thanks
— Alden
MemberThe default in both grbl and grblshield is 8x microstepping. However, it’s important to know that for grbl that’s only a parameter that goes into the calculation of the values for $0, $1 and $2. Refer to the grbl wiki configuration page to see how this works. For grblshield, 8x is actually set by the resistors. Check the grblshield wiki to see how that works.
The value of microstepping is confused, and overrated. 8x is not necessarily beter than 4x, 2x or 1, and higher microstep values are not necessarily better than 8x. The best microstepping value for an application is a compromise between the following factors:
– power (torque) needed at high speed (the higher the microsteps the less the power – in general)
– smoothness of motor operation (1x is pretty rough – higher values get smoother – to a point)
– the maximum step rate of the control software (grbl has a max or 30,000 pulses per second, tinyg 50,000)TinyG can also set microsteps to 1x, 2x, 4x, and 8x.
MemberYou can use an ATX supply with +12 and +5v (assuming you have done all the right things with the power-on switch lines, voltage sense lines and loading as required). There are plenty of articles on the interwebs about how to convert an ATX supply into a “bench power supply” that address these issues. One caveat: I have had trouble using power supplies harvested from a particular generation of Dell desktop – so be careful if the PS originated in a Dell.
Using 12 volts for the motors works fine. Using 24 volts just works better, regardless of the type of motor. Most of the Reprap world uses 12v and is quite happy with it.
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