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#1 2016-04-08 23:02:44

mandreas
Member
Registered: 2016-03-13
Posts: 136

Calibrate the projector

Hi Shahin,

I propose an idea, to rapidly calibrate the projector:

it comes to adding a window on the page "Projector Calibration", this window projects a red pattern with a dial gauge defined  (5 cm or 10 cm, for example), with this method the parameter "xy resolution" becomes secondary, (but still to be defined by intuition)
we're going to print with the home printer on a sheet A4, the same pattern 1: 1 scale, the sheet will be positioned above the surface of the vat , and we're going to zoom  or move the projector up or down , up that fits in perfectly with the paper ...
I hope it is a useful idea....

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#2 2016-04-09 00:00:37

Shahin
Administrator
Registered: 2016-02-17
Posts: 3,536

Re: Calibrate the projector

Hi,

It is a very useful feature.
I have couple of suggestion to extend the feature.

  • Supports both red and white drawing (to be compatible with uv projectors)

  • In addition to 5cm and 10cm dial. Lets put some common object sizes such as credit card, half dollar coin. It would be helpful to check sizes with plate full of resin.

  • Unfortunately as I know, in the most of cases platforms are bigger than printable area. But they could be a awesome measurement tool as there no needs to worry about resin. Maybe put laser marks on platform. 5cm and 10cm line which should be matched with mark on platform.

  • Definable outline rectangle

I have not tried focus projector using dot instead of lines (or small empty circles). Maybe it could be easier to user. It just a guess.
http://www.aaarpinball.com/Miscellaneous/p1080.htm

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#3 2016-04-09 18:29:07

adam
Member
Registered: 2016-02-18
Posts: 100

Re: Calibrate the projector

If I may add my 2 cents, until now for me the only real calibration option is printing one defined length and then calculating the x/y resulotion from that. It is absolutely correct and is not prone to human error. The pattern method might be good if you need to have a defined resolution but i've never come across a real use case for that. for the calibrate-by-printing method, you don't need to change the setup (remove vat etc..) at all.

Furthermore it's almost impossible to see the lines correctly if you have an UV projector and the eye cannot really focus on the pattern smile

For focus calibration I use a mobile phone/digital camera with live preview. there you can zoom in and focus to perfect pixel precision with not much hassle.

I hope you've found my suggestions useful,

Cheers!

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#4 2016-04-09 19:23:32

mandreas
Member
Registered: 2016-03-13
Posts: 136

Re: Calibrate the projector

yes @ Adam,

I understand your method, and it is certainly effective and precise, you have to consider one thing: I build a printer "top down" in which, there is not a constant printing table level, because it changes ,depending of the  tank contained resin level, so I need a quick method of calibration at  beginning of each print.
In the bottom up, the operation you advice, is  functional , because it will be done only  one time at all ,

Cya

p.s. my "baby"...
th_DSC_0849.jpg

Last edited by mandreas (2016-04-09 19:30:59)

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#5 2016-04-14 20:22:38

adam
Member
Registered: 2016-02-18
Posts: 100

Re: Calibrate the projector

Haha, sorry, i totally dropped the top-down from my mind.
My apologies. In that case i retract my comment ^^

Cheers!

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#6 2017-01-16 17:26:48

jaidek
Member
Registered: 2016-11-19
Posts: 29

Re: Calibrate the projector

I hate to bring up old threads, but has there been any developments on setting proper scale for top down printers? I am looking for something similar to how CW handles it. I measure the projected area, input the dimensions, print a 20mm cube then measure. If the scale is off, I just input the prints measurements and it calculates the proper scale. This has been the one thing that has been keeping me from fully pursuing nanoDLP as my main printing software.

Thanks!

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#7 2017-01-16 19:51:07

mandreas
Member
Registered: 2016-03-13
Posts: 136

Re: Calibrate the projector

jaidek wrote:

I hate to bring up old threads, but has there been any developments on setting proper scale for top down printers? I am looking for something similar to how CW handles it. I measure the projected area, input the dimensions, print a 20mm cube then measure. If the scale is off, I just input the prints measurements and it calculates the proper scale. This has been the one thing that has been keeping me from fully pursuing nanoDLP as my main printing software.

Thanks!

Hi Jaidek,

I used the following method (see attached pictures):
1_ raise the plate  on the resin level, but clean,
2_ from  "projector calibration" of nanodlp, active "boundary"
3_ position a sheet of paper,
4_  I draw with a pen the angles
5_  measures the longest side (eg 125 mm),
mathematical calculation: 125/1920 = 0.065 (65 microns to be set on nanodlp)
that's it, then you can make tweaks scale x / y or z (Override X / Y Resolution).
I developed a pan, however, that stabilizes the projection plane, it works very well, and just do calibration only once,

th_P_20170116_202347_p.jpg
th_P_20170116_202554_1_p.jpg
th_P_20170116_202631_1_p.jpg
th_P_20170116_202705_1_p.jpg
th_P_20170116_202752_1_p.jpg
th_P_20170116_202802_1_p.jpg

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#8 2017-01-17 00:07:30

jaidek
Member
Registered: 2016-11-19
Posts: 29

Re: Calibrate the projector

Thanks mandreas! That is some very helpful information and will be giving it a try this week on my top down. Can you talk more about the pan that you developed?

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#9 2017-01-17 12:26:11

mandreas
Member
Registered: 2016-03-13
Posts: 136

Re: Calibrate the projector

P_20170117_132314_1_p.jpg

level of detail achievable with pan

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#10 2017-01-17 13:30:23

jaidek
Member
Registered: 2016-11-19
Posts: 29

Re: Calibrate the projector

Wow, that looks great! What micron and about how many milliseconds per layer? I'm still in the tweaking phase of my top down, getting some really nice prints, just some are a bit rough on the undersides so I am trying to find that curing sweet spot.

As for the pan, I am still not sure I understand what it does exactly. Is it just used to hold your resin?

Thanks again!

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#11 2017-01-17 16:37:51

mandreas
Member
Registered: 2016-03-13
Posts: 136

Re: Calibrate the projector

jaidek wrote:

Wow, that looks great! What micron and about how many milliseconds per layer? I'm still in the tweaking phase of my top down, getting some really nice prints, just some are a bit rough on the undersides so I am trying to find that curing sweet spot.

As for the pan, I am still not sure I understand what it does exactly. Is it just used to hold your resin?

Thanks again!

44 micron XY
30 micron Z
3 Burn layer          @ 60 sec.
30  after burn layer @ 10 sec.
normal layer         @ 3,5 sec.
 

the main problems of the "top down" system are : inconstant resin level and  formation of bulges during exposure to UV rays, which produce geometric anomalies,
to solve these problems a solution is to use a pan according to the drawing

P_20170117_172348_1_p.jpg

Last edited by mandreas (2017-01-17 16:44:50)

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#12 2017-01-17 17:54:16

jaidek
Member
Registered: 2016-11-19
Posts: 29

Re: Calibrate the projector

Thanks mandreas! That is ingenious! Is it using FEP film or just glass? Last question, are you using dynamic curing (3,5) on the normal layer?

Thanks again for all the help!

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#13 2017-01-18 19:39:45

mandreas
Member
Registered: 2016-03-13
Posts: 136

Re: Calibrate the projector

here is a view in section of the pan :

a290d781-a91f-4873-81c2-74939420dbe6.jpg

P.s: no Dynamic curing  time

Last edited by mandreas (2017-01-18 19:44:30)

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#14 2017-01-19 00:22:50

jaidek
Member
Registered: 2016-11-19
Posts: 29

Re: Calibrate the projector

Very cool and thanks for the information. Does it have a peeling motion, or just works from the normal plate movement? I might have to give this a try during my rebuild. smile

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#15 2017-01-23 19:37:18

mandreas
Member
Registered: 2016-03-13
Posts: 136

Re: Calibrate the projector

jaidek wrote:

Very cool and thanks for the information. Does it have a peeling motion, or just works from the normal plate movement? I might have to give this a try during my rebuild. smile


the  detachment from the FEP sheet is by the natural elasticity of the film, you have to find the right speed of descent of the plate

Last edited by mandreas (2017-01-23 19:37:41)

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