PRO2 real speed much lower than set speed

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M_P
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PRO2 real speed much lower than set speed

Postby M_P » Wed Aug 15, 2018 8:26 am

Hi,
I realized by chance that the real speed of my Pro2 is much lower than the set speed.
I created a round tube of nozzle thickness 0.5, so the path of a layer is only the circumference 67.5 mm.
I set the minimum speed to 50 mm/s, so it should print a layer in about 1.35 s, instead it takes 5 seconds, the movement is not uniform, with constant speed but moves with many shots.

G1 F3000 X141.755 Y152.186 E54.4046
G1 X141.755 Y152.192 E54.4048
G1 X141.755 Y152.807 E54.4304
G1 X141.755 Y152.814 E54.4307
....

I tried the same gcode, on a cheap printer and the object is printed much faster, the real speed is the same as set and the movement is smooth with constant speed.

How can this happen?

Thanks for your help
Attachments
test_speed.stl
(286.96 KiB) Downloaded 20 times

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Vicky@Raise3D
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Re: PRO2 real speed much lower than set speed

Postby Vicky@Raise3D » Thu Aug 16, 2018 12:41 am

It sounds like due to acceleration.
May I ask which are your other printers?

M_P
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Re: PRO2 real speed much lower than set speed

Postby M_P » Thu Aug 16, 2018 9:01 am

The other printer is anycubic i3 mega, this printer makes a single acceleration at the beginning of the layer, then a constant speed and a deceleration at the end of the layer.

While the raise pro2, accelerates and decelerates for each coordinate of the layer, for this it moves in steps.

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Vicky@Raise3D
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Re: PRO2 real speed much lower than set speed

Postby Vicky@Raise3D » Fri Aug 17, 2018 1:24 am

It will be common that a Bowden type printer has higher acceleration rates than a heavy direct drive printer.

For your second paragraph, would you like to explain more about that?

FreedomRules
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Re: PRO2 real speed much lower than set speed

Postby FreedomRules » Fri Aug 17, 2018 2:59 am

Curious if you tried putting it in vase mode for cylindrical shapes to see if it printed as expected? What slicing software did you use? What was all your settings at?

Not sure stating that a direct drive will always be slower than bowden systems is a fair statement. The printer that MIT recently built is a direct drive system and it prints an estimated 10x faster than current printer on the market. So in my opinion that says any properly built direct drive can scream just as lightening fast as a Bowden system. To be fair I think the MIT unit is even heaver in regards to the head design than yours.

FreedomRules
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Re: PRO2 real speed much lower than set speed

Postby FreedomRules » Fri Aug 17, 2018 4:29 am

Vicky can you answer what the volumetric build rate of your printers are at the different resolutions. Preferable in cm3/hr measure scale.

M_P
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Re: PRO2 real speed much lower than set speed

Postby M_P » Fri Aug 17, 2018 7:20 am

The problem is not how fast acceleration is, which in the pro2 is also much more powerful.
In a linear path in which the two points are very distant, there is no problem, point 1 accelerates, decelerates point 2.
The problem is that in a circle path, the layer we put is composed of 100 points, very close.
The pro2 - 1 acceleration deceleration 2 acceleration deceleration 3 acceleration deceleration ... acceleration deceleration 100 (the pro2 in a layer of 100 points makes 100 accelerations and 100 decelerations)
The i3 - 1 accelerates 2 3 4 5 constant speed ... decelerates 100 (the i3 in a layer of 100 points makes 1 acceleration and 1 deceleration)

As a slicer I use Ideamaker for both.
As you can see from the attached file test_speed.stl the object is an empty tube in the middle, I put 50 mm / s for all the movements, the problem is that since the points are very close to each other it is not possible to accelerate and decelerate in a hurry, you have to be able to disable the deceleration acceleration for each point.

If it is not clear, I create a video.

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Vicky@Raise3D
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Re: PRO2 real speed much lower than set speed

Postby Vicky@Raise3D » Fri Aug 17, 2018 11:48 pm

M_P wrote:The problem is not how fast acceleration is, which in the pro2 is also much more powerful.
In a linear path in which the two points are very distant, there is no problem, point 1 accelerates, decelerates point 2.
The problem is that in a circle path, the layer we put is composed of 100 points, very close.
The pro2 - 1 acceleration deceleration 2 acceleration deceleration 3 acceleration deceleration ... acceleration deceleration 100 (the pro2 in a layer of 100 points makes 100 accelerations and 100 decelerations)
The i3 - 1 accelerates 2 3 4 5 constant speed ... decelerates 100 (the i3 in a layer of 100 points makes 1 acceleration and 1 deceleration)

As a slicer I use Ideamaker for both.
As you can see from the attached file test_speed.stl the object is an empty tube in the middle, I put 50 mm / s for all the movements, the problem is that since the points are very close to each other it is not possible to accelerate and decelerate in a hurry, you have to be able to disable the deceleration acceleration for each point.

If it is not clear, I create a video.


Understood your point.
The difference between is how divide a circle. In Pro2, a circle will be divided into a lot short segments which may be more than i3 you are comparing with. If the same test goes to be with a cube, the difference of time won't be that big as there won't have such many short segments to switch acceleration and deceleration between.

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Vicky@Raise3D
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Re: PRO2 real speed much lower than set speed

Postby Vicky@Raise3D » Sat Aug 18, 2018 12:45 am

FreedomRules wrote:Vicky can you answer what the volumetric build rate of your printers are at the different resolutions. Preferable in cm3/hr measure scale.


If you give enough temperature the nozzle needs, the linear speed can reach to 120mm/s. Which means the volumetrically rate of a 0.4mm nozzle can get 9.6mm2/s with 0.2mm resolution.

M_P
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Re: PRO2 real speed much lower than set speed

Postby M_P » Sat Aug 18, 2018 2:12 pm

Vicky@Raise3D wrote:
M_P wrote:The problem is not how fast acceleration is, which in the pro2 is also much more powerful.
In a linear path in which the two points are very distant, there is no problem, point 1 accelerates, decelerates point 2.
The problem is that in a circle path, the layer we put is composed of 100 points, very close.
The pro2 - 1 acceleration deceleration 2 acceleration deceleration 3 acceleration deceleration ... acceleration deceleration 100 (the pro2 in a layer of 100 points makes 100 accelerations and 100 decelerations)
The i3 - 1 accelerates 2 3 4 5 constant speed ... decelerates 100 (the i3 in a layer of 100 points makes 1 acceleration and 1 deceleration)

As a slicer I use Ideamaker for both.
As you can see from the attached file test_speed.stl the object is an empty tube in the middle, I put 50 mm / s for all the movements, the problem is that since the points are very close to each other it is not possible to accelerate and decelerate in a hurry, you have to be able to disable the deceleration acceleration for each point.

If it is not clear, I create a video.


Understood your point.
The difference between is how divide a circle. In Pro2, a circle will be divided into a lot short segments which may be more than i3 you are comparing with. If the same test goes to be with a cube, the difference of time won't be that big as there won't have such many short segments to switch acceleration and deceleration between.


Both pro2 and i3 divide the circle by the same number of points.
The only difference is that the pro2 decelerates for each point, while the i3 only the final point of the circle.

So in pro2 can not deceleration be disabled?

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Vicky@Raise3D
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Re: PRO2 real speed much lower than set speed

Postby Vicky@Raise3D » Tue Aug 21, 2018 12:52 am

I don't believe it is possible to disable deceleration on Pro2.


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