Print Speeds explained

[changedsoul 2]

I have seen many posts where people ask questions on speeds for printing, how to solve print problems, etc.

Responses usually come back as print with "what ever" mm/s.

My question is, is this "what ever" speed the "Main - Print Speed" in cura, leaving cura to calculate all the others, infill speed, perimeter speed, wall speed, automatically?

So for example if someone says to print with say "50mm/s", that is referring to the Main Print Speed value, which will give a much slower Wall Speed, top/bottom speed, etc, correct? Assuming cura is left to auto calculate those values.

[neotko 1,417]

Depends. I don't use cura at all but last versions have a lot of speed downs by default to gain quality at the expense of print time. I use s3d and I set my print speed 90% of the time at 60-70mm/s 0.2 layers with default max acceleration/jerk

Most of the UM by default (without improvements) can't do good quality beyond 50mm/s so all depends on your setup. And um3 max real speed is around 20-30mm/s for default profiles. Sometimes even less when uses the acceleration/jerk tricks to remove ringing on the external perimeters at the expense of bad infill. All that settings are hidden by default, on s3d you have access to all the settings and there's no hidden/non-easy to edit from the program (by default).

So, max speed is something that 90% of the printer sellers try (consciously or unconsciously) to hide. Also there's no much culture out there about print vs quality vs speed. Most of the time, specially 3d printer reviewers) don't establish a definition of this. That also why I have change my printers to the point that they are hardly UM (except the frame and gantry).

Also is important to add that all changes with nozzle size, material, need or no need for extra slow speed for adhesion, how much the material drips, etcetcetc.

One should need a table of basic test setup like X brand + X size nozzle vs X max print time. Then the machine and settings makers should need to make the best of their machine for a defined frame.

Edited July 3, 2017 by Guest

[changedsoul 2]

Right, but so for your case, the 60-70mm/s, is that all moves? For example, infill, top/bottom layers, external/internal walls, etc. Is everything set at a flat 60-70mm/s? Or is that a generic speed, and all sub items (walls, infill, top/bottoms) printing at a calculated different speeds.

[DaHai8 74]

For both S3D and Cura, Print Speed refers to the Infill Speed. All other speeds are calculated from that, and at a lower value - if left up to the Slicer.

In Cura it is: Speed -> Print Speed

In S3D it is: Other tab - Speeds -> Default Print Speed

Hope this helps.

[neotko 1,417]

S3D speeds. For example, you set the Main speed. Then you set Under or Over speeds (less than 100% or more than 100%) for the Outlines, Solid infill (top and bottom - but don't confuse bottom with first layer) Also you set travel speed for non printing moves and Z speed.

Edit: Forgot to explain an important thing. Outlines underspeed. If you set it to 50% for example and you use 3 Perimeters each one will slow down progressively.

For a 70mm/s main speed and 50% underspeed for outlines:

First inside perimeter will be 70mm/s - 11.67mm/s = 58.34mm/s

Second inside perimeter would be 70mm/s - 23.34mm/s = 46.66mm/s

Outside perimeter at 50% slow down would be 70mm/s - 35mm/s = 35mm/s

Then also... First layer has it's own settings

As you can see first layer has a Speed %. Also this one can be Less than 100% or More than 100%. So it will take the speed layer and Slow it down or Speed it up by that %. Usually used to slow down the first layer for better adhesion.

THEN this is the tricky one that not many users know about

This if activated sets a minimum layer speed. It will automatically slow down each layer speed to force a minimum time per layer (if activated). ALSO the important thing, is the 'Allow Speed Reductions down to'. If you have that activated will affect to the first layer print speed. For example if you set an underspeed max of 50% then even if you set the first layer speed at 10% it will set it at 50% because you have a 'Allow speed blabla' max of 50%. Complex? Well lets go to cura now

This is Cura 2.6 UM3 Fine profile print speeds for pla. As you can see all is unhide (default shows much less). They have specific speeds for each part, also specific acceleration/jerk, and much of this data will automagically change without you knowing it unless you unhide it. So... I leave a Cura expert to explain all this long enchilada

Edited July 4, 2017 by Guest

[changedsoul 2]

Thanks for the detailed explanations, this answers my question quite well.