3D Printer performance data

General discussion of 3D printers

3D Printer performance data

Postby tmccafferty » Sun Mar 10, 2013 5:02 am

Has anyone seen a definitive performance comparison of the more popular open source printers? It would be interesting to compare technical performance parameter that affect print speed and quality. Things like accuracy, resolution, speed, max accel,... Has anyone seen anything like this?

It would bee interesting to have something like this for extruders as well?

If it doesn' exist, I guess the place to start would be to define the important parameters to compare. You would have to make sure each entry was properly tuned.

Seems like it would be a good tool to decide what to build, but would also definitively define areas each design could improve.
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Re: 3D Printer performance data

Postby orcinus » Sun Mar 10, 2013 1:36 pm

There are too many parameters that vary from individual machine to an individual machine. Caused by the environmental parameters, things like squareness, tolerances, variations in components... I'm afraid you'd have to test a boggling number of samples of each construction to reach any (statistically) meaningful conclusion.

And that's after you settle for a testing procedure you can guarantee will work on and for all the constructions.
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Re: 3D Printer performance data

Postby richmond » Sun Mar 10, 2013 4:28 pm

I'm not certain that one of the biggest benefits to such an undertaking wouldn't be to create a standard that printers would reach toward. Similar to video card test suites, there are too many variables to wait for standards to emerge, but if you create a benchmark first and measure how well printers do. Sure environmental conditions play a part but they can be recorded as well.

Perhaps a couple test objects that would evaluate
1) Squareness
2) Levelness
3) Layer resolution
4) Layer consistancy
5) etc.

I like some of the test objects already in place but perhaps an x shaped object with a set number of layers to test levelness across the xy axis, a pillar test next where you test the height of pillars on extremes of a symmetrical object with calipers to ensure they are all the same height, time to print a fixed size reference object once all the other tests are done, and publish your results. I would hate to see it devolve into competition (too much anyway) but if you have the same architecture as someone else and they get better results you can compare the builds to see why.
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Re: 3D Printer performance data

Postby cvoinescu » Sun Mar 10, 2013 5:44 pm

I have a feeling that printers do not differ substantially in the basic, static accuracy -- and with many of them being kits, these depend a lot on the skill and patience of the builder, as well as on the design. You can rate them, subjectively, on the ease of squaring and levelling -- useful information, but not easy to devise a good test for.

Some criteria have a habit of becoming meaningless (can't help thinking "capture resolution after software processing" for cheap webcams). For instance, the theoretical Z resolution of a leadscrew design is very fine -- but does it make sense to say the ORD Bot has a layer resolution of 3.125 microns? That's the smallest vertical displacement possible with a 0.9 degree motor in full step mode (with 16x microstepping, it's about 0.2 microns), but can you actually print anything with 0.003mm layers (let alone 0.0002mm), and is the result any better than 0.2mm layers? We know that the quality of the print begins to degrade below a certain layer size (the threshold being somewhere around 0.1..0.2mm in the test I read about). My point is that the parameter you can determine objectively (Z axis resolution) is meaningless, and the one you really care about is subjective and depends on too many factors.

Layer consistency touches a sensitive spot -- that's good. The ORD Bot can suffer from at least two modes of "Z wobble" (periodic vertical unevenness, and periodic horizontal displacement coupled to Z movement). An interesting metric for printer designs with allthread as leadscrew would be how much of an error is caused by a given curvature of the rod, or by a given misalignment of the coupling to the motor. Again, not an easy thing to standardize and measure, and it would not say much about a particular instance of printer.

My main point, however, is that many errors are of dynamic nature, and difficult to quantify. Sharp cornering can cause parts of the printer to oscillate, imprinting a wavy pattern into the printed object. Backlash can cause problems too. An extruder can ooze, or it can have a slow response of actual extrusion vs. motor movement. One extruder may deposit a nice, smooth line of filament, while another, although driven in a straight line, may deposit a more variable shape or quantity. All are things you see in the print, yet it's often hard to tell what the cause of a problem is, let alone measure it to compare printers.

I agree that it would be useful to have a small suite of objects that could be used to evaluate printer performance. However, simply measuring them would not be enough; evaluation will have to be at least somewhat subjective. And you'd have to study several printer designs carefully, think of what inaccuracies would affect the print and how they would affect it, and design objects that are likely to catch them, and to help distinguish between them. It's not easy!
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Re: 3D Printer performance data

Postby orcinus » Sun Mar 10, 2013 9:51 pm

What about filament? Or particular flavours and brands of hotends? Hobbed bolts? Extruder gears?
Just changing to a different filament color (from the same filament maker) can change the result *drastically*.

I've had radically different results just by switching between Ultimachine white and Ultimachine silver filaments. White was extremely inconsistent layer-wise, silver was good. And i'm not talking about a slight difference observable under a loupe, one was butt fugly, the other was great.

Heck, even a shift in temperature of a few degrees up or down will influence things like layer consistency significantly and you can't guarantee everyone's thermistor is calibrated to even within 5 degrees much less 1.

It's not impossible, but it would either have to be one person testing multiple bots or a *very large* user base so you can cover all the possible variations and draw direct comparisons without unwanted variables causing any differences. Neither option looks very feasible to me.
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Re: 3D Printer performance data

Postby MaryDelko » Tue Apr 09, 2013 4:05 am

I think that most of the people consider only basic things like resolution, speed when it comes to printer.Most of us are actually unaware about many technical things out there.

replacement ink
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