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printer speed average test

Posted by jamesdanielv 
printer speed average test
July 01, 2011 06:16AM
it would be nice if we had a torture test for printers so we know how they ran fast. here is an stl file that can be run with infill turned off. the speed of printer is mm distance travel/time completed. the test pasts if it successfully builds up the walls. with infill off nozzle size should not matter only perimeter distance. also thinner layers should not matter because it increases distance. the test also provides a reference of where the printer weaknesses are, and the limits to the firmware.

also as part of the spec, a fastest theoretical speed should be provided, that is fastest actual tested maximum pulsed per second on x or y axis, and fastest pulses per second with and x and y move. divide those numbers by the minimum stepper multiplier used to pass the stl test

here is a printer its specs according to the benchmark are:

printer speed: mm/s [unknown]
theoretical limits are: [unknown]
single axis speed: [unknown]
multi axis speed: [unknown]

this is torture test, and it includes 45,47 deg angles and 2 sizes of circles, and a large area for acceleration results. this test will provide a more reliable average speed for printers.

OK here is a genuine test for printers. this tests uneven angles , 45 deg angles, circles of various diameters, and allows range for acceleration.

it is 3mm high, so it does involve more than 2 passes. to run the test, turn off infill, and setup the max speed you have for your printer, time it until complete, and then divide it by the mm distance total travel.

if the printer passes the test then the speed value can be stated as the max speed of printer. if this object is successfully printed at that speed,. then it is considered a stable speed for printer. If a firmware is optimized to work for this stl it will be stable at the speed it ran. a printer passes the test if with infill turned off, it outlines the inside and outside of object, and produces the object to 3mm in height consistently. it is not important that it is perfectly aligned to pass this test, just that it builds up the walls completely.

here is stl file stl test file

i am posting this both in firmware section and general sections.
Re: printer speed average test
July 01, 2011 12:22PM
Your test needs to test for short lines that often occurs with infill. Not just to test if they infill properly but to see if the sudden change in direction causes missed steppes.

I have been trying to increases the speed of my printer and the mechanics of the moving parts has not been the biggest problem.

The problem is getting the plastic to come out fast enough. If you have ever tried pushing the filament by hand in to a hot end then it becomes quite clear that much less pressure is needed to extrude at slow speed than is needed to extrude at high speed.

I'm sure there are fluid flow laws that govern this that I don't understand but is is extremely obvious pushing by hand.

The result is it takes more time to build up pressure in my extruder running at high speed and so tends to not start threads properly. This could be because of a poor fit between the filament and the wall of the heat insulation allowing molten plastic to ooze up as pressure builds instead of pushing through the nozzle. But I'm not sure.

My torture test is just to print stuff and see if it does it properly.

Make your Mendel twice as accurate.
Re: printer speed average test
July 01, 2011 02:18PM
Yes when you extrude faster the pressure is more so the plastic compresses more, has to be rewound further to stop ooze and so fast forwarded further. The rewind / fast forward speed needs to be much faster than normal extrusion, so when extrusion is itself very fast you struggle to be able to rewind/fast forward fast enough. You need less gear ratio, which means a more powerful motor.

The pressure increases linearly with flow rate but at some point the plastic doesn't have time to melt fully so the pressure then rises much faster. To mitigate that you need a bigger melt chamber, but then that also needs more rewind.

Re: printer speed average test
July 01, 2011 02:30PM
I'm getting the distinct feeling that there is a practical limit to pushing plastic through a .5mm nozzle.

The only way I can see going faster now with my hot end is to have thinner layers so I'm depositing less. Which makes the build time the same though you might get a nicer finish.

The other way round it would be to have a bigger size nozzle so it pushes easier and keep the layer height the same as well as the height/thickness ratio but move the nozzle faster to keep that ratio the same as before.

Probably going to work on my remote extruder and not worry about this for a while.

Make your Mendel twice as accurate.
Re: printer speed average test
July 01, 2011 03:31PM
ok so the test needs to also test for extrusion speed? the circle would likely test the short lines. and of course it could be switched to have infill. the distance would be increased correct? so distance traveled /time taken still would apply.

i was hoping for a baseline that would show average print speed. max print speed currently is meaningless.

Edited 2 time(s). Last edit at 07/01/2011 03:44PM by jamesdanielv.
Re: printer speed average test
July 01, 2011 05:09PM
Max speed should probably be qualified with volume/hr at a particular layer height instead of a linear velocity.

I don't see the usefulness of max speed anyway, since most of us (I'm assuming from what I've observed) only want to print where the quality is reasonably high (somewhat below the max speed, usually)

Perhaps "Maximum deposition volume at layer height of X while maintaining acceptable print quality" would be better? Needs a good acronym :p
Re: printer speed average test
July 02, 2011 01:03AM
Ok anyone else?. how do we differentiate between printer specs for firmware?
Re: printer speed average test
July 02, 2011 08:18PM
ok updated test. includes circle infill and rectangle infills.

stl test file

here is what it looks like modified

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