drawcut wrote:FYI, simple way to think about it:
Velocity (speed) is the rate of change of position.
Acceleration is the rate of change of velocity.
Jerk is the rate of change of acceleration.
drawcut wrote:ETA: Jerks are bad.
not yet, but it's a good idea. Print speeds and finish times are a LOT faster when you start to turn up acceleration.
I now tend to print at below 80mm/sec. but I have 2x travel speed and 3x Max acceleration of 1year ago. Things print a lot quicker.
; generated by Slic3r 0.9.8 on 2013-01-23 at 21:19:12
; layer_height = 0.35
; perimeters = 3
; top_solid_layers = 3
; bottom_solid_layers = 3
; fill_density = .1
; perimeter_speed = 40
; infill_speed = 65
; travel_speed = 195
; scale = 1
; nozzle_diameter = 0.35
; filament_diameter = 3
; extrusion_multiplier = 1
; perimeters extrusion width = 0.37mm
; infill extrusion width = 0.37mm
; first layer extrusion width = 0.70mm
M107
M190 S75 ; wait for bed temperature to be reached
M104 S230 ; set temperature
M92 X44.3118; calibrate X
M92 Y43.8036; calibrate Y
M92 Z2028.95 ; calibrate Z
M92 E502; calibrate E
G28 ; home all axes
M116 ; wait for temps to settle
M205 X20 ;max XY Jerk speed
M201 Y700 ; max Y acceleration
M201 X700 ; max X acceleration
M109 S230 ; wait for temperature to be reached
G90 ; use absolute coordinates
G21 ; set units to millimeters
G92 E0
M82 ; use absolute distances for extrusion
mikemwa53 wrote:Can you also list your Gcode?
M203 X200.00 Y200.00 Z2.00 E14.00 ; set max speeds for XYZE
M201 X700 Y700 ; set XY acceleration
mikemwa53 wrote:...I've been able to bump up the speeds without any adverse effects except that the corners stick out more than normal. Not sure why. ...
#define DEFAULT_MAX_ACCELERATION {9000,9000,100,10000} // 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.
RetireeJay wrote:Another point is that the wooden bed on a Printrbot Plus seems to have much more wood than absolutely necessary. It extends 4" beyond the heater, when less than one inch would do. >>snip<<The big problem for me is: If I shorten the bed then I must drill new holes for attaching the clamps that hold the mounting rods - and the distance between these holes needs to be VERY precise in order to keep the rods exactly parallel.
gyronictonic wrote:...
I have a feeling that cutting holes to lighten the mass of the Y carriage is going to compromise the structural integrity of the wood bed. ...
I'm interested about that vibration test. The new slic3r added a new but untested feature that gives you the ability to fiddle with the frequency or vibration. I can also perform this test and give you the data.
generated by Slic3r 0.9.8 on 2013-02-05 at 23:43:59
; layer_height = 0.3
; perimeters = 3
; top_solid_layers = 3
; bottom_solid_layers = 3
; fill_density = 0.1
; travel_speed = 150
; scale = 1
; nozzle_diameter = 0.5
; filament_diameter = 3
; extrusion_multiplier = 1
; perimeters extrusion width = 0.70mm
; infill extrusion width = 0.70mm
; first layer extrusion width = 0.60mm
MegaMoonMan wrote:Adjusting that acceleration setting from 2000 down to 700 really helps with bumpy corners. I also upped my max speed from 60 to 100 without much quality degradation.
plexus wrote:This may be why PBHQ set the firmware max speeds to 60mm/s because higher nominal speeds don't translate to actual speed.
holmes4 wrote:Why would a lighter motor help on the X axis? The only motion of the X motor is in the Z direction.
plexus wrote:It could be that there is no one ideal setting for accel and jerk for given speeds. or it could be variations in our printers. but i get better results slow to fast with faster acceleration. however 9000 is just too much at fast speeds. so i am using 4000 and 25 and that seems ok. maybe its then pointless to share these numbers as universal settings??
plexus wrote:Ok I figured it out. it was nice to use google to search for this and find the first link this thread on printrbottalk. i merged my thread below into this one...
ok so there are max speeds set in the firmware. if you do M501 you get M203 X60.00 Y60.00 Z2.00 E14.00
so for my configs, anything above 60 was being ignored! this explains why i was thinking i wasn't getting anything faster than a moderate speed. even though i set the parameters in slic3r.
so i opened up the throttle by manually entering M203 X200.00 Y20.00 Z5.00 E14.00 **did you mean 200.00?-**
I experimented with Z and found 5 to be the fastest I could go up. now with my fast configs... ITS FAST! wow...
i am printing a small cube now to test it. its printing very fast at around 150-170mm/s. print quality is down but at least now i can get the fast speeds.
you have to put the M203 command in your g-code header. be careful with this as it will make your PB print very quickly which may result in undesirable results or even permanent damage. know what you are doing.
pomonabill221 wrote:I have created several print speed "profiles" using slicer/configure/print settings/speed and also added the custom G codes to set max speed, X,Y,Z stepper calibration values and acceleration as I did see the EEPROM values change a couple of times and don't know why it did that, so I wanted to make SURE I override the eeprom settings when I print.
They do show up in the generated Gcode after slicing so I know the calibrated values are there.
WOW, the fastest REALLY makes the printer MOVE!!! I didn't use any filament YET, but will time a couple of prints and see if the printer is really moving as fast as the profile is set for... speed isn't necessarily the goal, but speed AND quality are so we'll see!
Thanks alot for this thread! Very helpful!
violadavis wrote: It causes electromagnetic noise and loss within the motor cables. Eventually it will lead the wires to negate each others' signals at higher speeds. FalconFour is absolutely right about all this.
I saw your posts here viewtopic.php?f=15&t=1124 but, I was having a little trouble adapting them to my software. I am learning how to use Simplify3D and it is my understanding from your post that you can set many of the speeds on your firmware and tell the printer how to behave with the software but, the firmware will always be the overwriting source. I am unsure what settings I should be setting in Simplify3D in order to get similar results you have. The only speed settings I see in software however is the "default printing speed" under the "other" tab for FFF settings. I don't know if you have used this software before but, can you clear up any settings I need to set in addition to the firmware changes? I mainly noticed that the particular thread was old so I was looking for more updated info.
Mooselake wrote:I'm sure you remember the 200mm/sec (12000mm/min) guys here http://www.printrbottalk.com/forum/viewtopic.php?f=21&t=979.
Did you do an M203 and up the max speeds? I'm at the wrong computer and don't recall what the defaults are, but IIRC they were pretty low. M503 (just type M503 in the command window) will tell you what the current settings are). They're somewhat arbitrarily set, remember Marlin isn't aimed at just Printrbot's and I don't believe the defaults were adjusted in the Printrbot specific version. They're also in mm/second (mm/minute vs mm/sec is a frequent confusion issued) so multiply by 60 to get mm/min (the feedrate on G commands is mm/min). You're limited by the speed of the slowest axis, but thinking about how X, Y,Z, and the extruder limits would interact is beyond my insufficiently caffeinated brain.
Marlin claims a 30kHz step rate, or around 460 mm/sec with the pbot's X and Y around 65 steps/mm. Like all marketing claims that 30kHz is probably overstated, but 20k should be pretty doable (around 300 mm/s X,Y, 10 mm/s Z, 30mm/sec Z)). That's still audio range, the stepper wiring shouldn't be an issue at that low a frequency. See CL1's microstepping discussions elsewhere, too. If you ever get to where Marlin's a limit check out linuxcnc.org - I get a 50kHz step rate (way faster than the hardware) on the machine that drives my CNC router.
Jerk (basically how fast you can yank an axis sideways while it's moving?) seems to be a big topic in research circles, but the discussions and papers are from the academic crowd. They rapidly degrade into math that's beyond my 40+ year old memory of all those classes I took in ee school. FF4 probably understands it a lot better than I do.
Don't let all the reasons why it won't work discourage you. Bump up the max speeds and play with the acceleration and jerk values (one a time, of course) and see what your one of a kind Pbot will do! If you have a way to video your bot (with a ruler somewhere in the background) and then single step through the individual frames it would be real interesting to see just how fast it's really going.
All you risk is a pile of blobs in the saved for filabot box, maybe vibrating your bot onto the floor, and a massive explosionof flying bot fragments.
Kirk
Edit: fix min/sec mistake
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