Calibration using laser beam

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ivan.akapulko
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Calibration using laser beam

Post by ivan.akapulko »

Because I regularly work with geodetic instruments as tacheometers and levels there was a following idea: a separate addition to the UM hotend block with the following functionality: red laser diode 675nm, the signal receiver and display with the indicator of the difference of the distance to the optimum. Ie If you want to increase the level when calibrating on X. XX mm, the screen shows this figure. Calibration is completed when the display of the readings is zero.The power of a typical laser diode with a wavelength equal to 3.2 Volts. As a base i think to use something like the Arduino Nano with custom shield.
What do you think, folks?
reibuehl
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Re: Calibration using laser beam

Post by reibuehl »

Just for my slow understanding: That would be for bed leveling, correct?

If so, would the glass bed not create strange reflections?
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Re: Calibration using laser beam

Post by ivan.akapulko »

Yep, exactly.

The principle of operation of the laser rangefinder of any type works with the reflection from the glass prism/other reflective surface. Up to one hundred meters of measurement can be carried out even without it.
Of course we are talking about relatively powerful lasers that can give distances up to 15 kilometers under good weather conditions.
In our case, the laser power is small, and because of this I don't think glass will give anything like a serious error.
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LePaul
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Re: Calibration using laser beam

Post by LePaul »

What about ultrasonic or feeler-type probes to check distance?
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Re: Calibration using laser beam

Post by reibuehl »

I thought I have read somewhere that you get reflections from the glass surface and (to a lesser extend) from the shiny aluminium of the heated bed underneath the glass.
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Izzy
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Re: Calibration using laser beam

Post by Izzy »

The only thing with these guys is what you are actually interested in is not just bed levelling which we do after every time we swap out the glass bed plate but also the nozzle tip to plate gap.
I use a mix of postit notes to a thickness of 1mm for the 1st level set then a couple cut at an angle so I can use as a stack of feelers for 0.1mm gapping. After this I try printing a few thin discs at 3 points and check their thickness and adjust. Some times simple works.
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Re: Calibration using laser beam

Post by jonnybischof »

The problem about most of these sensors is that you will need 0.01mm accuracy in order to be able to justify the high cost of such a setup.
Like Izzy described, you can go 0.1 or even 0.05mm without any hokus-pokus, and without too much hassle.

Don't forget that if a sensor's datasheet says 0.01mm, it doesn't mean your application will actually live up to that spec. Also, don't forget that most printing surfaces don't even come close to a 0.01mm surface flatness.

I've been thinking a lot about making some kind of auto-bed levelling feature. My conclusion was that it's not worth putting the money and effort in. I just use a thick first layer (0.25mm) and a sturdy z-stage and never really have any problems with bed levelling. I hand-levelled my bed once, and never touched it again...
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Re: Calibration using laser beam

Post by LePaul »

jonnybischof wrote: I hand-levelled my bed once, and never touched it again...
These are the guys I envy in life :lol:
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Re: Calibration using laser beam

Post by jonnybischof »

It's the little things, right ;)
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Izzy
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Re: Calibration using laser beam

Post by Izzy »

Hope this works :geek: below should be a picture of my high-tech bed levelling tool
image.jpeg
Now the tech specs.
The handle in the middle is a wooden coffee stirring stick.
The 'soft feeler gauge' pad ends consist of a stack of 'post-it' type notes, the top few are cut to give stepping as you get the approximate depth. Each layer is approximately 0.085mm thick, so my thick end is ~1.0 with a step either side.
Thin end is 0.17mm and 0.085mm
The pads are cut slightly to suit the width of the coffee stick and sticky tape is wraped about them to retain them in place.
Please feel free to make your own on a N.C. Licence, there is a fee of "Hi" over a cup of coffee if we ever me up some day :-D
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