Future Project: Laser engraving for arrows (Carbon)

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Orngrimm
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Future Project: Laser engraving for arrows (Carbon)

Post by Orngrimm »

Well well well... Here we are again with an exciting new idea... an not real time to follow up on it.
Ill put it here for talking and ideas. As soon as i find time, i will post updates hre or start (and link) a thread in "Projects".

OK. Cut to the chase!
Short intro on marking of arrows:
High quality arrows like Easton X10 have a C-weight determined. If you want to know more about C-codes and why they matter in archery, please open a thread and i will be happy to explain and talk...
Anyway: Since about 2018 Easton started to mark their C-code (+serial number) as laser etch on the shaft itself and no longer prints them as GFX on the individual shaft-label.
See https://www.archerytalk.com/threads/eas ... 1107320657 for example.

Now... As with foil-fletches (Spinwings, Spider, XS, Eli performance vanes, and so on...) one needs to have the baseline precise in position, angle and length. Once we have this baseline on the arrow, you can fletch and refletch the vanes on the fly with the doublesided tape and securing tape. Only thing needed is the markings of the baseline.
In international competitions, one also needs to mark the name and country (but the controls on that are rather lax).
Anyway: What if we could just laseretch those lines and maybe even name, country and number onto the round shaft?
Well... Welcome to my idea...
It is quite easy to design a FLAT design which should be wrapped around the shaft while lasering. There are cheap 20W electric (About 5-7W optical 450nm) laser engrver in an open frame configuration. Why the config is important in a minute...
Now, the laser should be able to mark the carbon. Tuning for clear but only a few micrometer deep marks need to be done. I think high power, but short pulses should do the trick.
The challenge will be to mark a 2D flat image around a 3D round shaft.
Thats where the open frame configuration comes into place: I will just disconnect one axis and connect it to a own stepper with driver. One which is connected thru a gear (timing belt with a ratio bethweeen the 2 gears). This will turn the arrow (secured in a drill-chuck-head) exactly as fast as it needs to to translate the axis to rotation based on the diameter of the arrow. Different arrow-diameter will need different ratios.
But then, it should be possible to laser-etch the 2D flat image onto the full circumference of the 3D round shaft.

So... Thats the basic idea.
The laser engraver is ordered from Aliexpress (160$), motor (with TMC2130) and chuck are already available from other projects.

If you want to comment or have ideas, feel free to post. Thats what this forum is here for...

PS: No: I dont think it will etch anodised aluminum. It may bleach the anodisation back to clear transparent, but to remove amorphous aluminum oxide one needs CO2 or fiber lasers i think... We will try it for sure but the hopes in this venue are slim ;)
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Downunder35m
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Re: Future Project: Laser engraving for arrows (Carbon)

Post by Downunder35m »

Back in my days Marlin had a feature already for a rotating "bottle" holder of sorts.
Never really took off due to the extreme hassle of height adjusting of this spinning contraption.
But arrows are not really that much different in their diameters, so this part could be neglected in favour of a fixed base.

I had a similar idea before I had to move house.
For me it was not arrows but glass test tubes.
With my CO2 laser I noticed a severe shortcoming here in terms of accuracy in relation to font size.
As it turned out CO2 lasers work great on glass and many other things but their focussing is rather limited.
Even with multiple passes at quite low energy levels the results were always lacking the detail.
Did a paper test and noticed that the optics won't keep the dot size when the power increases.
There seems to be some sorts of glare, reflection or whatver causing the beam to get wider the higher the power levels are.

Have a look if the current Marlin version still support the rotation addon.
It is really much easier with it than trying to convert the linear motion of one axis into a rotary one.
Plus you can still use the engraver for normal engraving without having to change the firmware all the time.
A 32bit board certainly helps here as you want to do this engraving on resin coated arrows in fast scanning lines.
If you want to go simple and maybe even add a diode laser to your 3D printer aim for something with much more power than what you really need - helps the diode to survive longer.
The blue lasers should work reasonably well on resin, not 100 sure on the carbon part though as I never had anything to test.

One thing to keep in mind and for consideration is how big you can actually engrave on an arrow.
I guess a line of text should not be higher in font size than about 1/4 or 1/3 than what is visible from looking on the tube.
Industrial marking lasers use a wavelenght that is rather short to allow for these extra fine details in micro size.


I might be thinking in the wrong direction but what about etching with a resist film?
A quick blast with fine sand would do the trick just fine.
Depending on the resin even wiping with a solvent and then wiping with some bright paint should work reasonably well - and cheap.
Since it is carbon electron etching with high voltage might work fine as well to just burn the top layer of the resin coating.
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Orngrimm
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Re: Future Project: Laser engraving for arrows (Carbon)

Post by Orngrimm »

Intere4sting note on the feature of rotation in marlin. Ill have to check if that is still there.

But you may have misunderstood me: I will add an additional stepper and go thru a gear to have the SIGNALS of one axis converted to the correct angular movement. The original motor and stuff stays in place but gets disconnected by unplugging the cable.
So basically, all that has to be done to convert from Arrow-mode back to flat-mode is unplugging the rotation-motor and plugging in the axis-motor again.
This is the beauty of this all: You can design the font and lines in 2D and the gearing automatically converts it to the proper rotational-lasering on the shaft.

The 450nm should work reasonably well for carbon. I once saw them cutting thin carbon mats with laser in this region.
Focusing will be a challenge i think... Those cheapo chinese lasers are not known for nice optics ;)
But i already got options to buy high grade optics for a penny and an egg from the local university.

Size: The markings can be more than 1/3 or 1/4 of the side of the tube. They are not meant to be read on the quick. A field-judge will inspect the arrows once beforehand of a competition. And as long as the markin is there and readable (Even by turning the arrow) all is OK. See, those markings are only a requirement for some very special cases of shot-too-many-arrows and cheating. Often they also find use in the case when you have a pass-thru (And you dont find it on the quick) and notify the field-judge. The field-crew will search the arrow after competition. Whose arrow was this we just found? Because we found like 10... ? Read the country, send it to their hotel, hotel gives to the head of delegation, he gives to the archer. Simple.
It is really a thing you should never HAVE to read. ;)

But back to topic... I think there WILL be a bunch of challenges ahead. I am eager to see what my engineering-brain will do with them :D
Builder of stuff, creator of things, inventor of many and master of none.
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Downunder35m
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Re: Future Project: Laser engraving for arrows (Carbon)

Post by Downunder35m »

What you want to do with gear is an additional motor setup in Marlin, or at least it was back then.
I know it is still implemented in several custom ports for laser engraving.
Comes down to the same bsics as your approach but allows for very easy adjustments if you would have to deal with more than one diameter.
And whow knows, you might like the idea of laser engraved bottles of glasses one day ;)
I do like the whole pulg and play idea though :)

If you go diode I might have a solution for your problem of optics if you are willing to build a custom laser rig for your arrows.
The biggest problem with these "cheap" china lasers is not always the optics they came with.
It is their focussing lenght!
In most if not all cases the optics used are to provide a parallel beam, usually at least the same diameter as the actual diode chip.
Due to the nature of things those original optics really struggle with the concept of creating the samllest, most energy rich point possible.
As a result the use ends with more a big blob of stray light than actual dot.
Sold my diode setup when I moved house and figured out too late the landlord won't allow me to use any bunring laser in the house :(
I used a beam expander as the main optics on the laser.
I got it back then as a set from some china guy on Alibaba - what a hassle that was lol
From there and with the help of a 3D printed mount it went into a lens with a long focus factor, if I am not mistaken it was just over 35cm.
With that setup the laser energy at full level was still not enough to have any effect on the printed pastic but I used a charded metal ring anyway to block the outside mm of the expanded beam from entering the focus lens.
The diameter was matched so that about 15-20 of the lens outer area was free from the laser light - helps to prevent the distortion.
Thanks to this very long fous system it is possible have a lot of freedom when it comes to properly placing the part to be lasered.
Instead of let's say about 1mm of distance to have have a more or less focussed dot you have almost a cm where the beam stays very, very narrow.
The real beauty for your application is:
You can mount the laser with the beam expander stationary along the x-axis and use a morror and lens on the moving part.
Eliminates the weight and allows for very fast scanning speeds.
And as a desktop solution it would not take much more room in the y-dimension than what you need as a stand to the x-axis only framework.
Reduces Marlin to basicall just two axis to worry about wich in return means using a dedicated milling firmware instead of a modified 3D printing firmware might be the easiet way out.
Especially once you consider the many dedicated projects for using lasers instead of a rotating head.
Laser engraving is more common on CNC setups than on Marlin setups, so might be worth considering this alternative as well.
Exploring the works of the old inventors, mixng them up with a modern touch.
To tinker and create means to be alive.
Bringing the long lost back means history comes alive again.
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