Calulate rapid prototyping stl build time

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Discussion Overview

The discussion revolves around calculating the time required to build a part using rapid prototyping techniques, specifically focusing on the application of a formula related to 3D printing. Participants explore the implications of various parameters such as scanning speed, layer thickness, and part geometry on the overall build time.

Discussion Character

  • Technical explanation
  • Mathematical reasoning
  • Homework-related
  • Debate/contested

Main Points Raised

  • One participant presents a formula for calculating the time to complete a layer, which includes variables for area, scanning speed, spot size, and delay time.
  • Another participant explains how to apply units to the formula, suggesting that understanding the units clarifies the calculation process.
  • Concerns are raised about the accuracy of manual calculations, noting that actual print times can vary significantly based on factors like part shape and infill density.
  • Some participants suggest that for prismatic parts, the total time can be calculated by multiplying the number of layers by the time per layer, while non-prismatic parts may require more complex calculations.
  • There is a discussion about the assumptions in the formula, such as infinite acceleration and 100% infill, which may lead to inaccurate results.
  • One participant mentions that the question originated from an exam context, indicating a need for manual calculation despite the availability of software tools that can automate this process.
  • Another participant suggests that choosing a better orientation for the part could lead to faster calculations and more efficient use of exam time.

Areas of Agreement / Disagreement

Participants express varying opinions on the accuracy and practicality of the formula provided, with some agreeing on the need for additional considerations in the calculations, while others emphasize the limitations of manual calculations compared to software solutions. The discussion remains unresolved regarding the best approach to calculate build time accurately.

Contextual Notes

Limitations include assumptions about part geometry, infill density, and the effects of acceleration on print head movement, which are not fully addressed in the formula. The discussion also highlights the variability in actual print times based on different factors.

SagarPatil
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I am not sure where this goes , if this is the wrong place sorry.

The question is asking for
Time required to build the part.

upload_2015-4-18_11-49-0.png


The 4 is the total length of the part.

It also says the scanning speed is 80ft/min
the spot size is 0.010 in
delay time is 7 sec/layer

The formula that is given

Ti=(Ai/(vD))+Td

Where
Ti= time to complete layer
Ai=area of the layer
v= average scanning speed of the laser beam at the surface
D= diameter of the spot size
Td= delay time between layers to re position the worktable

I want to know the steps of this formula.
 
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Are you familiar with how a 3D printer works?
If you put units into the formula and it should become clear.

Ti=(Ai/(vD))+Td
Time taken = (area to be covered / (speed of print head * width of printed line) + time to reposition for next layer
Seconds = m^2 / (m/s * m) + Seconds

If you know the layer thickness you can expand the formula to give a total time to make the part.

Of course most parts are not printed with 100% infill so actual time may be significantly shorter.
The actual time is difficult to calculate accurately (by hand) as it depends on the part shape, the slicing method, infill shape x, y, z max acceleration etc etc
Most slicer programs can calculate it for you.
 
billy_joule said:
Are you familiar with how a 3D printer works?
If you put units into the formula and it should become clear.

Ti=(Ai/(vD))+Td
Time taken = (area to be covered / (speed of print head * width of printed line) + time to reposition for next layer
Seconds = m^2 / (m/s * m) + Seconds

If you know the layer thickness you can expand the formula to give a total time to make the part.

Of course most parts are not printed with 100% infill so actual time may be significantly shorter.
The actual time is difficult to calculate accurately (by hand) as it depends on the part shape, the slicing method, infill shape x, y, z max acceleration etc etc
Most slicer programs can calculate it for you.
Yes, I am familiar how 3D printing works. I have printed a few parts. I know that the printer will calculate the time, but the question is asking to caclulate manually .

So when I calculate the time

(I am choose the bottom surface)

Ai=3*4 = 12
v=16in/second
D=0.01
Td=7

When I enter it in the formula I get

82 seconds

82 seconds gave me the time to build 1 layer

The question is asking how long will it take to build the whole part.

 
SagarPatil said:
The question is asking how long will it take to build the whole part.

If the part is prismatic then each layer takes the same time so clearly:
total time = #layers * (time/layer)
To calc. #layers you need this information:

billy_joule said:
If you know the layer thickness you can expand the formula to give a total time to make the part.

If the part is not prismatic, you'll need to derive an expression for area as a function of height. Then maybe a bit of integration.

Your formula assumes infinite acceleration of the print heat & 100% infill - not a realistic model and will give poor results.

Is this homework? If it isn't, why not just use the printers software? Or upload your STL to an on-line print calculator? Anything else will not be accurate.
 
billy_joule said:
If the part is prismatic then each layer takes the same time so clearly:
total time = #layers * (time/layer)
To calc. #layers you need this information:
If the part is not prismatic, you'll need to derive an expression for area as a function of height. Then maybe a bit of integration.

Your formula assumes infinite acceleration of the print heat & 100% infill - not a realistic model and will give poor results.

Is this homework? If it isn't, why not just use the printers software? Or upload your STL to an on-line print calculator? Anything else will not be accurate.

This was a question from a exam where you have to calculate the time it takes. I know printers can calculate the time, but what can I do.

When you calculate the time which was 82 seconds

You divide the thickness/height by the layer thickness. The layer thickness can be any reasonable number.

So in this case 1/0.02 = 50

So 50*82 = 4100 seconds to make the bottom part

Do the same thing on the top part.
 
Yes, that's right. If you choose a better (ie prismatic) orientation you'll get the answer faster.
Let your image be the plan view/layer shape then layer area is constant and you have more time for other exam questions.
 

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