Thankyou for such a helpful answer. I need to get this nailed as I now using two ultimakers in my shop.
So basically try and keep perimeters and infill the same speed. say 50 - 60 for "average quality"
Travel 150..
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two other questions -
Retraction 40mm/s ? at 4.5mm
does cura always Retract on layer change?
The reason for the questions, is I'm trying simplify 3d and very annoyingly all the settings are in mm/min
thanks
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gr5 2,295
You are talking about the error caused by minimal steps (max resolution of Z axis) but the resolution is so high that it doesn't matter. I looked into this about a year ago. .1 and .2 are fine. Don't worry about this - it's silly.
Well - I usually do 150mm/sec because that's plenty fast for me and the non-printing moves tend to be rare - the long moves anyway. On the short moves it never gets up to 150mm/sec. Some people do 250mm/sec. I think the max speed is 300mm/sec. Before going that speed you should test the repeatability using prontrface which is free, and easy to use GUI, and you can do lots of 300mm/sec moves back and forth and see if you lose any steps. Probably you will be fine:
http://koti.kapsi.fi/~kliment/printrun/
Doing 80mm/sec for fill and 50mm/sec shell will lower the quality - speed change will result in over extrusion when it slows down. A little bit. But if you don't need "perfect" quality, and if you don't care too much about stringing, I can print at .2mm layers, 100mm/sec or maybe even 200mm/sec if you heat up the PLA to 240C. Here are some photos that explore the relationship between speed, temperature, quality:
http://umforum.ultimaker.com/index.php?/topic/1872-some-calibration-photographs/
In general, "perfect" quality is around 30mm/sec. But you can do fine at 100mm/sec if you aren't picky.
Another huge speed improvement I have found with zero quality reduction is to not print any infill. The UM is amazing how good it can bridge openings - for example the top layer of a cube with no infill. This means however that you need the top/bottom thickness to be a layer or 2 thicker than if you use infill. Usually 4 layers is plenty. The latest Cura (14.02) is now very accurate about predicting how long a print will take. So you can fiddle with more top layers and less infill and see how much time you will save.
The strength of a part comes mainly from the outer edge - that's why bones are hollow and the wood beams in a house can be drilled only in the center (for plumbing/electrical) without sacrificing strength, etc.
Speeding up the Z axis won't print any faster but will print with better quality. I doubled the default Z acceleration and it changes layers twice as fast. Didn't need to touch the max Z velocity. This helps the Z seam quite a bit.
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