[Discussion] Distance, default acceleration and "plausible" speed

Hey there,

Before I dig into it, I've just done my first build so I'm a noob for now. So take it easy on me.

My first printer still has some issues that I'm trying to solve like oozing and other stuff. Yet, I get very nice prints at 25mm/s (more on the numbers later) with default Acc settings of 60mm/s^2 (I know now that this is too low). So I print a part in three hours a small low poly pokemon and it looks great. Then I looked at my speeds and try to undertsand how things work to get greater speeds. I increase my default acc to 3000 and then setup the speed in slic3er at 25 like usual. I start my print and it waaaaay much more faster in a negative way so build quality suffer a lot. then it hit me...

1- Those who are reporting to be printing on 100mm/s on youtube mostly are NOT reaching those speeds. I tried and saw what a 100mm/s looks like with enough acceleration and it's waaay faster than what i saw on youtube.
2- let's take a step back and examine those numbers anyways; 25mm/s is 2.5 CM/s and 100mm/s is 10CM/s that is insane speeds!!!!! think about it for a second. 10 CM in each second. and of course since your printer moves are too short the printer, in most cases doesn't reach those speeds. this issue is also discussed by Thomas on his channel [www.youtube.com]

now I have many questions
1- what are a "good" sensible def acceleration values?
2- what are the actual speed that we are REALLY reaching during prints?
3- what are "good" sensible achievable printing speeds? A speed that we can actually achieve!

The achievable accelerations and printing speeds depend on the printer design, and you haven't said what printer you have. My Ormerod (Cartesian) printer works well at 1000mm/sec^2 acceleration, and my Kossel (delta) can handle at least 2000mm/sec^2. I slice using 30mm/sec for perimeters, 21mm/sec for external perimeters and 50mm/sec for infill. But these figures are conservative, and after the first layer I often turn my Ormerod up to 150% speed and my delta up to 200% or even more - which means I am printing long infill moves at 100mm/sec or more on the delta.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

Quote
dc42
The achievable accelerations and printing speeds depend on the printer design, and you haven't said what printer you have. My Ormerod (Cartesian) printer works well at 1000mm/sec^2 acceleration, and my Kossel (delta) can handle at least 2000mm/sec^2. I slice using 30mm/sec for perimeters, 21mm/sec for external perimeters and 50mm/sec for infill. But these figures are conservative, and after the first layer I often turn my Ormerod up to 150% speed and my delta up to 200% or even more - which means I am printing long infill moves at 100mm/sec or more on the delta.

Sorry for missing that out I've a Prusa i3.. I will reply more later...

Quote
dc42
The achievable accelerations and printing speeds depend on the printer design, and you haven't said what printer you have. My Ormerod (Cartesian) printer works well at 1000mm/sec^2 acceleration, and my Kossel (delta) can handle at least 2000mm/sec^2. I slice using 30mm/sec for perimeters, 21mm/sec for external perimeters and 50mm/sec for infill. But these figures are conservative, and after the first layer I often turn my Ormerod up to 150% speed and my delta up to 200% or even more - which means I am printing long infill moves at 100mm/sec or more on the delta.

I know that delta is superior in terms of speed. Don't you think 1000mm/s^2 is too much? How is the quality you're getting??

I have just checked, and I am actually using 800mm/sec^2 on X and Y axes of the Ormerod, not 1000mm/sec^2. I increased the motor currents to 1000mA from the default of 800mA, although I am not sure this is necessary. Print quality is good at 100% speed, acceptable at 150% speed, and poor at 200% speed (all using the same acceleration setting).

However, I see that in October last year, RepRapPro reduced the acceleration from 800 to 500mm/sec^2 in their default config.g file for the Ormerod. So maybe I'll try 500 and see if print quality gets even better.

---

Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

Quote
dc42
I have just checked, and I am actually using 800mm/sec^2 on X and Y axes of the Ormerod, not 1000mm/sec^2. I increased the motor currents to 1000mA from the default of 800mA, although I am not sure this is necessary. Print quality is good at 100% speed, acceptable at 150% speed, and poor at 200% speed (all using the same acceleration setting).

However, I see that in October last year, RepRapPro reduced the acceleration from 800 to 500mm/sec^2 in their default config.g file for the Ormerod. So maybe I'll try 500 and see if print quality gets even better.

I started with 2000mm/s^2 and decreasing every time I skip a step. I'm printing [www.thingiverse.com] since I'm still calibrating the retraction as well.
I got down to 1500... I hear people all setting at 3000mm/s^2 is ordinary!! I really want someone else to highlight their experience with a Cartesian system with a 3000

My machine, with its massive bed and drive screw in the Y axis, is running at 1000 mm/s^2 and producing extremely high quality prints at 40mm/sec print speed. If my printer can do that while driving all that mass, I would think you guys ought to be able to set acceleration and print speed a lot higher. Right now my machine has external drivers on the X and Y axis motors with 32V supplies, but before I installed the drive screw, external drivers and 32V supplies the machine was running at 3000 mm/sec^2 acceleration, using the pololu module and 12V supply on the RAMPS board.