TT_Vert
Posts: 24
Joined: Mon Jan 08, 2018 12:48 am

Print time estimate way off (More than double?)

First, I did search and did find a few older posts (2-3 years old) but I had hoped things had changed w/ the latest and greatest S3D.

So it seems that maybe more lately that my print times are signifigantly longer than the "build time" shown in the software. An example, I have a print which said it would take 1 hour 28 minutes and I'm now 2 hours and 40 minutes in and it's only at 58%. I don't recall this doing this before but to be honest I never paid attention until recently when things seemed to be taking way longer than the estimate. I have a maker select v2. I was playing w/ print speed since I don't care so much about the finish of these pieces so I increased print speed from my normal medium print speed of 100mm/sec to 150mm/sec just to see what would happen. To my surprise it printed fine (A bit rough). I printed via SDCARD. I wonder if something in the printer is throttling down the speed? I don't have a trained enough of an eye to determine the actual speed it's printing at but it cannot be 150mm/sec. I've included the first 1.386 lines of gcode as the entire file is too large.

Note that until today I printed via USB but the USB port on the printer gave up the ghost. Perhaps there is some sdcard read speed limitation (Not likely) but just trying to come up w/ some rationale for this behavior.

Looking at my gcode it is defining print speed @9,000 mm/min and first layer speed properly @33% (2,970 mm/min) and then back to 9000mm/min for the second layer. I then notice it throttles it back again and I'm not sure why. I do know it reduces speed for walls, infill, etc. yet the time calculation is far different than actual.


Last lines of code:
; Build Summary
; Build time: 1 hour 28 minutes
; Filament length: 32308.7 mm (32.31 m)
; Plastic volume: 77711.50 mm^3 (77.71 cc)
; Plastic weight: 97.14 g (0.21 lb)
; Material cost: 4.47
Thanks
Dave
Attachments
Partial.gcode
First 1386 lines of gcode.
(39.32 KiB) Downloaded 260 times
rrdavis
Posts: 421
Joined: Sat Dec 09, 2017 4:52 am

Re: Print time estimate way off (More than double?)

TT_Vert wrote:I wonder if something in the printer is throttling down the speed?
Yes, that is exactly what is happening. Many printers have a max speed setting that will limit any speeds that you send to the machine. So you could increase the print speed 10X, and it might not make a difference since the printer will limit it. Printers also usually have settings that limit the rate at which the speed can increase (acceleration), and unfortunately, the small inexpensive printers usually have much more restrictive limits for these settings as well. So a $200 printer with a cheap wooden frame is going to have a much worse restriction than a $3000 printer with high end motion systems and bigger motors.

If you can modify the firmware on the printer, you can increase some of these limits and you would see the printer would go much faster when printing the exact same file. But keep in mind that the limits are usually there for a good reason, because most printers have a limit on how fast they can move before they start to have issues with vibrations, layer shifting, skipping steps, etc.
TT_Vert
Posts: 24
Joined: Mon Jan 08, 2018 12:48 am

Re: Print time estimate way off (More than double?)

Can you tell me what settings in FW would limit this exactly? I'd love to learn more about these and play w/ them to see what happens.

I looked and this is what I found but I'm not exactly sure if these are in mm/min, steps, or what they represent.
Print X: 1000
Print Y: 1000
Print Z: 100
Move X : 1000
Move Y: 1000
Jerk: 20.0
Z-Jerk: 0.3

Max X: 200
Max Y: 200
Max Z: 2
Home X: 40
Home Y: 40
Home Z: 2

Steps/MM: 96.0 (Verified was dead on)
Start FR: 20
Max FR: 50
Accell: 5000
Stab.Time: 1

Wait Units: 0mm
Wait Temp. 150C
Control: Dead Time
DT/PID P: 7.00
PID I: 2.00
PID D: 40.00
Drive Min: 40
Drive Max: 230
PID Max: 255
rrdavis
Posts: 421
Joined: Sat Dec 09, 2017 4:52 am

Re: Print time estimate way off (More than double?)

Max FR: 50 <--- maximum feedrate limit
Accell: 5000 <--- acceleration limit (limits how fast the speed can change)
TT_Vert
Posts: 24
Joined: Mon Jan 08, 2018 12:48 am

Re: Print time estimate way off (More than double?)

Thanks I know what a few of them are. Are these steps, mm/min??


Dave
arhi
Posts: 463
Joined: Thu Oct 06, 2016 5:13 pm

Re: Print time estimate way off (More than double?)

accel is mm/sec/sec
max fr depends from fw to fw but usually mm/min
jerk and junction deviation are unitless
gcodestat integrates with Simplify3D and allow you to
Calculate print time accurately (acceleration, max speed, junction deviation all taken into consideration)
Embed M117 codes into G-Code
Upload your G-Code directly to Octoprint
open source and unlicence
skelator
Posts: 11
Joined: Fri May 08, 2015 4:18 am

Re: Print time estimate way off (More than double?)

The main question is what is the defaults value used by the S3D? I think it more sane if user able to change the S3D settings instead of re-flashing firmware? assuming all printer have the same speed are not really suitable for a software that can support multiple type of printer hardware
TT_Vert
Posts: 24
Joined: Mon Jan 08, 2018 12:48 am

Re: Print time estimate way off (More than double?)

Thanks guys.
arhi
Posts: 463
Joined: Thu Oct 06, 2016 5:13 pm

Re: Print time estimate way off (More than double?)

skelator wrote:The main question is what is the defaults value used by the S3D?
s3d ignores these values, and for time calculation, I think, they don't take acceleration into account at all (indefinite acceleration, so they assume movement from A to B is done at constant speed instead with trapezoid-shape speed change you get on marlin, smoothieware and most other firmwares or s-shape speed change on some more advanced electronics) and that's why the time calc is off by a lot.
skelator wrote: I think it more sane if user able to change the S3D settings instead of re-flashing firmware? assuming all printer have the same speed are not really suitable for a software that can support multiple type of printer hardware
you can change these using M204 in your startup script (or add it throughout the final file with additional post-processing to have different acceleration settings for different features)... most firmware's support this (at least marlin and smoothieware do) so no need to reflash the firmware just add something like "M204 S1000" to your starting script to set 1000mm/sec/sec acceleration for your XY movements... look at the M204 explanation here:
http://reprap.org/wiki/G-code#M204:_Set ... celeration
http://marlinfw.org/docs/gcode/M204.html
http://smoothieware.org/supported-g-codes
gcodestat integrates with Simplify3D and allow you to
Calculate print time accurately (acceleration, max speed, junction deviation all taken into consideration)
Embed M117 codes into G-Code
Upload your G-Code directly to Octoprint
open source and unlicence

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