Problem - Overspeeding

Hey all,

Trying to get my first print for calibration going...
The issue I'm having is when I start the print (the calibration cube)
The machine heats up, then 'ZOOMS' into position... problem is,
it overspeeds, and looses steps. I have to stop it before it self destructs!!

I left the defaults in the marlin firmware(2000mm/min for X/Y and 100mm/min Z)
In the software, I have the same speeds set (Even tried 200 and 50mm/min)

but as soon as the machine is warmed up and starts to move... its WAY too fast.

I not sure what settings I have missed, can you point me in the right direction?

Thanks!
Chris

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Custom all metal CoreXY
- Duet 2 Wifi w/ PanelDue 7i
- 330mm x 360mm x 500mm
- 750w Silicon heater

Custom Mendel90
(Backup printer - Old reliable!) - Sold

Have you done any calibration of steps/mm? If this number is set too high for your system it will cause your system to move too rapidly. Check out here: [calculator.josefprusa.cz] to get an idea of what numbers to use for this.

Additionally, are you looking at HOMING_FEEDRATE or DEFAULT_MAX_FEEDRATE? The units here don't match up; homing is in mm/min, but max feedrate is in mm/sec (though even if that is your mistake, 50 mm/sec is pretty slow and shouldn't be a problem).

Other than that, I'd recommend making sure you don't have some incorrect value stuck in EEPROM. I haven't really used the EEPROM settings, so I don't know the specific command off the top of my head, but the wiki should point you in the right direction.

Here is a copy/paste of my movements in the firmware.
I have gone through Joe's Calc to get my steps, and they are pretty much bang on.
(I still have to calibrate my E though)
I see now that the feedrate is mm/sec... I'll lower that and see what I get.

I'll also have to investigate the EPROM (I've never looked into it)
Thanks!

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//// MOVEMENT SETTINGS
#define NUM_AXIS 4 // The axis order in all axis related arrays is X, Y, Z, E
#define HOMING_FEEDRATE {10*60, 10*60, 2*60, 0} // set the homing speeds (mm/min)

// default settings

#define DEFAULT_AXIS_STEPS_PER_UNIT {80,80,2535,760*1.1} // default steps per unit for ultimaker
#define DEFAULT_MAX_FEEDRATE {2000, 2000, 50, 1000} // (mm/sec)
#define DEFAULT_MAX_ACCELERATION {5000,5000,100,10000} // X, Y, Z, E maximum start speed for accelerated moves. E default values are good for skeinforge 40+, for older versions raise them a lot.

#define DEFAULT_ACCELERATION 4000 // X, Y, Z and E max acceleration in mm/s^2 for printing moves
#define DEFAULT_RETRACT_ACCELERATION 5000 // X, Y, Z and E max acceleration in mm/s^2 for r retracts

//
#define DEFAULT_XYJERK 10.0 // (mm/sec)
#define DEFAULT_ZJERK 0.0 // (mm/sec)
#define DEFAULT_EJERK 10.0 // (mm/sec)
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--------------------------------------------------------
Custom all metal CoreXY
- Duet 2 Wifi w/ PanelDue 7i
- 330mm x 360mm x 500mm
- 750w Silicon heater

Custom Mendel90
(Backup printer - Old reliable!) - Sold

Yeah, those feedrates are really high. I'd switch back to the Marlin default, at least (500, 500, 5, 45). The only change I've made is lowering my Z to 2.5, because I have a Prusa i2 with anti-backlash springs, so my pololu burns out if I run it any faster.

Additionally, what slicer and host are you using? In reality, these X and Y speeds are still faster than the supposed maximum step frequency the current ATmega processors can handle, so the speed it's traveling at is actually probably either the travel speed set by the slicer or some speed set in the host.

Ah crap!
I just broke a wire off my hot end thermistor...
I haven't got another one, so outa commission till a new one gets here.
(How do I bypass the temps so I can still test things?)

I've re-flashed with the speed you recommend, how about acceleration? is that ok?

---

--------------------------------------------------------
Custom all metal CoreXY
- Duet 2 Wifi w/ PanelDue 7i
- 330mm x 360mm x 500mm
- 750w Silicon heater

Custom Mendel90
(Backup printer - Old reliable!) - Sold

Those accelerations should be fine, I use similar ones.

If you want to run it without a thermistor, set TEMP_SENSOR_0 in Configuration.h to 0 and it will let you move everything around without giving you temp errors. Additionally, if you want to pretend to print something (move everything like its printing but ignore the temp) M302 tells the printer to ignore temperature errors.

Thanks Topher!
I didn't know about M302, it'll come in handy until I get the new thermisters.

Chris

---

--------------------------------------------------------
Custom all metal CoreXY
- Duet 2 Wifi w/ PanelDue 7i
- 330mm x 360mm x 500mm
- 750w Silicon heater

Custom Mendel90
(Backup printer - Old reliable!) - Sold

All those defaults are really high and are designed for an Ultimaker with a really light carriage. Most machines can not accelerate that fast. A normal Prusa/Max etc would have a default accel of 1500-2000 and a max of 4000-5000 on x/y. The max speeds are also really high unless you have low acceleration that stop it from ever actually reaching those speeds. To start printing a perimeter speed of 45 and infill of 60 is a good place to start. Above that the quality usually starts to drop off.

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