Comparisons - what speeds do you get?

Hey all,

I'm just curious as to the communities' general consensus on 'reasonable' speeds are for an 'average' RepRap. I know, I know, there are so many variables in play here - I'll narrow them down to my scenario, and tell me how yours compares!

- Prusa i3, Alu frame, direct drive extruder
- Printing PLA onto PVA juiced glass, non-heated
- Acceleration at 500 m/s² (much smoother now it's lower than 9000m/s²!!)
At 0.3mm layers, I can get 100m/s prints without causing any side effects. I can usually dial up the feedrate to 150% without issue, but at these lower accelerations there's not enough distance to ramp up to full throttle across the print to make much effect.

At the original acceleration settings I would be game to try 50m/s, which ran the risk of missed steps and print fouling from knocking it off the bed.

What speeds do you get? Does a deltabot or Bowden make a significant improvement to speeds, or just slight? Let me know!

Switchblade

Edited 1 time(s). Last edit at 06/15/2014 07:54PM by Switchblade88.

100mm/sec is already very good according to me. I am happy with mine running at 40mm/s

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Switchblade88
- Acceleration at 500 m/s (much smoother now it's lower than 9000m/s!!)
At 0.3mm layers, I can get 100m/s prints [...]

For a more serious discussion - which would be quite interesting -, please try to get units right. Can we assume you mean 500 mm/s², 9000 mm/s² and 100 mm/s (without "²") ? These buttons right at the top of the edit field include ones to make a ₂ or ² from a 2.

Thanks.

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Generation 7 Electronics	Teacup Firmware	RepRap DIY

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Traumflug
Can we assume you mean 500 mm/s², 9000 mm/s² and 100 mm/s?

Indeed, just edited to correct.

I don't know about other firmwares, but Marlin's default is excessively high for any RepRap design; unfortunately I didn't realise that until further researching and traced it down as the cause of my missed steps. Upon fixing that, I could significantly push my speeds higher with less risk of failure overall.

Acceleration, while allowing higher speeds, lowers the quality of your corners.

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Realizer- One who realizes dreams by making them a reality either by possibility or by completion. Also creating or renewing hopes of dreams.
"keep in mind, even the best printer can not print with the best filament if the user is the problem." -Ohmarinus

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MrDoctorDIV
Acceleration, while allowing higher speeds, lowers the quality of your corners.

Agreed. The question is really what is better, high acceleration and lower speed or low acceleration and higher speed? In terms of print quality I see a huge, positive difference, when I print with my acceleration in the 9000 mm/s² range. As doc said, the quality of corners and holes on vertical faces are much cleaner.

Edited 1 time(s). Last edit at 06/16/2014 09:24AM by tkole.

I used to have an acceleration of 1000m/s², but have since raised to 4000m/s² and a bit slower speed, vastly improving my quality.

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Realizer- One who realizes dreams by making them a reality either by possibility or by completion. Also creating or renewing hopes of dreams.
"keep in mind, even the best printer can not print with the best filament if the user is the problem." -Ohmarinus

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MrDoctorDIV
Acceleration, while allowing higher speeds, lowers the quality of your corners.

Ah, it has taken RepRap how many years to recognize this simple fact of physics? Higher acceleration means higher forces and as such more printer frame bending. Not to mention a higher risk of step losses (which resulted in many people searching for position encoders / verification methods).

If you get better quality with higher acceleration anyways I'd guess it's due to the fact that extruders don't push out material immediately, but do so a bit delayed. On what "delayed" exactly means, experts debate for quite a while already.

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Generation 7 Electronics	Teacup Firmware	RepRap DIY

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Traumflug

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MrDoctorDIV
Acceleration, while allowing higher speeds, lowers the quality of your corners.

Ah, it has taken RepRap how many years to recognize this simple fact of physics? Higher acceleration means higher forces and as such more printer frame bending. Not to mention a higher risk of step losses (which resulted in many people searching for position encoders / verification methods).

If you get better quality with higher acceleration anyways I'd guess it's due to the fact that extruders don't push out material immediately, but do so a bit delayed. On what "delayed" exactly means, experts debate for quite a while already.

the bottom line people seem to forget also is that we are building printers, not race cars

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thejollygrimreaper

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Traumflug

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MrDoctorDIV
Acceleration, while allowing higher speeds, lowers the quality of your corners.

Ah, it has taken RepRap how many years to recognize this simple fact of physics? Higher acceleration means higher forces and as such more printer frame bending. Not to mention a higher risk of step losses (which resulted in many people searching for position encoders / verification methods).

If you get better quality with higher acceleration anyways I'd guess it's due to the fact that extruders don't push out material immediately, but do so a bit delayed. On what "delayed" exactly means, experts debate for quite a while already.

the bottom line people seem to forget also is that we are building printers, not race cars

But I would like to build me a nice Ferrari 250GTO some day. Maybe even a printer to compare.

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Realizer- One who realizes dreams by making them a reality either by possibility or by completion. Also creating or renewing hopes of dreams.
"keep in mind, even the best printer can not print with the best filament if the user is the problem." -Ohmarinus

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thejollygrimreaper
the bottom line people seem to forget also is that we are building printers, not race cars

Speak for yourself! I have a whole pile of full-sized race car parts sliced and ready to print.....

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MrDoctorDIV
I used to have an acceleration of 1000m/s², but have since raised to 4000m/s² and a bit slower speed, vastly improving my quality.

Ah, but the question here is - was it lowering the speed or raising the acceleration that made the improvement??

The jump from 1000m/s² to 4000m/s² will make the overall print speed more 'linear' (for lack of a better term) which I could see helping if there are extrustion inconsistencies (i.e. Bowden setups and the like). Printing at an even speed means extrusion is at an even speed and thus the effects of filament hysteresis are less pronounced.

I should note that I only changed my axial acceleration values, and left the extruder at 3000m/s². If you just change the MAX_ACCELERATION value that'll affect all the steppers, which I deliberately didn't want to do. This would also explain Doc's improvements after raising his values back up again; if that was the variable in play, the extruder's responsiveness would have been affected.

Switchblade

Edited 1 time(s). Last edit at 06/17/2014 12:13AM by Switchblade88.