Dimensional Accuracy
Firstly, I'd like to say I am extremely happy with the MK3 to date. I've printed over 40 hours now on various types of component and apart from a few learning issues on Slic3r it has performed flawlessly.
I did some research and calibration printing / testing yesterday and I am pretty happy with how things are now going. I would, however, appreciate some feedback as to my results and if anything else can be improved or if I have missed something!
Basically, my prints were perfect on internal dimensions and Z dimension but small on the external dimensions - all with Prusa PLA and the the stock 0.2mm layer height and PLA filament settings that came.
So I went to 0.5 mm perimeters and measured them. They were small and indicated an Extrusion modifier of 1.075 requirement. This then gave me an exact 1.0mm wall with two perimeters (+- 0.02mm ish).
This din't address the undersized part so I then played with the XY Compensation thinking that would help. I printed the a 50x20mm block with a 20x10mm rectangular hole in it. The 50mm was about 0.3 mm small. I measured the undersize on the external dimension and calculated the required XY addition. Note: The internals were already perfect (=- 0.02). Printing again with the calculated XY provided an almost perfect external dimension but the internal ones were now too small by the offset. Not what I wanted.....
I looked around again and thought I'd try the part scale. Again I calculated the scale from the original non scaled part and reprinted. This was 100.25. The part now seemed pretty perfect on both external AND internal dimensions.
Note I also turned on External Perimeters first and haven't tried it reverse yet.
So I'm not 100% sure how Slic3r deals with each modifier but the scale seemed to sort it out and not the XY thing. It would be good if this could be applied to the filament stored setting and not have to be reapplied to every part added individually.
However, does that all sound feasible? Has anybody any other experience?
Cheers
Re: Dimensional Accuracy
You can add gcode line in start section of printer settings.
M92 X100.25 Y100.25
Re: Dimensional Accuracy
That’s great!
Many thanks!
Re: Dimensional Accuracy
Actually - got a question on that. So the SCALE is not applied by the Splic3r but rather by the MK3 at print time?
I had kind of thought the printer just followed the curve it was given.......
Re: Dimensional Accuracy
Yes.
More here: https://shop.prusa3d.com/forum/prusa-i3-kit-building-calibrating-first-print-main-f6/why-is-m92-bad--t2928.html
Re: Dimensional Accuracy
Interesting. But M92 probably does not do the same thing as 'Scale'.
I'm guessing the gcode is written and M92 is applied to everything at run time.
If you do 'Scale' it scales the part before it slices it so the infill, for example, is still the correct ratio. With M92 the infill is also scaled but with Scale it is the per cent you set it at for any model size......I like 'Scale' better!