Photo engraving 2
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- čas přidán 10. 04. 2023
- Part 1 was all about the therory of digital graphics and how resolution and image size are intimately entwined. Dithered images are based on pixels but there are limtations on what size pixels can be reproduced with hobby laser macines. This part 2 is all about creating small dots with a laser machne to emulate pixels. It's not as simple as most users think. There are many factors that will ultimately affect the size of a burnt dot. These include the material, the lens type and its orientation, the intensity profile within a laser beam and the laser beam control system.
This session demonstrates that if you can create dots to match a pixel size, then you can do photo replication with no image "interference" or "preperation".
The little 254ppi bitmap test pattern used in this video can be downloaded with this link
workdrive.zohopublic.eu/exter... - Věda a technologie
You are the best! Ive been watching for years and appreciate the super educational videos you make
I’ve had my laser for about a year. 60 watt co2. I’ll admit I tried watching your videos then, but all info was way over my head. Now a year in, I can’t watch enough. So much information! Great information at that!
Amazing, very intuitive. Thankyou 👍
Russ, I wish I had seen this a couple of weeks ago. I was doing a photo engraving on slate. I fiddled and fiddled with the picture and got a decent engraving but it was not perfect. The customer was estatic however. I did the engraving with a fiber laser. Now using what I have just learned I think I will be able to produce much better results.
Hi Kris
The real secret with the fibre laser is to set the frequency correctly
If you are using an image of 254ppi that means the pixel size is 25.4mm (1") divided by the ppi ie 25.4/254= 0.1mm square. This means there are 10 pixels per mm. So, if you choose to run at say 400mm/s that meams you will be dotting at the rate of 4000 pixels per second. You must match this number when you set your frequency ie 4kHz.
Best wishes...Russ
@@SarbarMultimedia thanks for that bit of information. See, every time I communicate with you I learn something new. Now, if this adlepated old brain can retain all this new information. Take care my friend.
Another well thought out and incredibly informative video :)
Awesome masterclass!
What size is that metal tube for the air you stuck into the cloudray lens tip? Did you have to weld or glue it in?
Hi Russ, thank you so much for the educational videos you've been making! I have learned so much from them. You definitely have a talent teaching. Wonder, though, how/where did you learn all this stuff yourself. For instance, there is no much info at all for RDworks and unless yours and couple of other's videos one cannot learn it.
in this video, at around 16:41, the lines you etch are wavy. It's especially pronounced on the thinnest lines. I have this same problem with my 100W Chinese Co2 laser. On mine I attribute this issue to the X linear carriage being too lose on its rail - no preload there. Consequently, each movement in Y (which precedes each X movement) causes vibration in the Y direction do to wobble of the X carriage.
Have you attempted fixing this? I have been thinking of buying a preloaded carriage.
Hi
When I retired from an engineering career that was multifacated,and included a 10 year spell running a precision sheet metal business that included two large CO2 metsl cutting lasers, I decided to buy a cheap Chinese laser to "play" with and to keep my two remaining grey cells execised.. Coming from a background where I had learnt a lot about lasers , I felt this would be an easy downscaling. How wrong I was. This was like stepping onto another plannet and if 5% of what I knew was transfereable, even that may be an exaggeration.It was a junk machine with a junk tube tat the Chines sold as a dream rather than a usable machine. After some tesing and fiddling (my naivety was immense) I bought a replacement tube from Ebay. Mistake number two! I replaced rubbish with rubbish.. With CZcams in its infancy there were no recources to guide me.I decided to call upon my life time of engineering skils and problem solving to make sure I did not repeat my stupidity. I began to slowly learn about laser tubes and how they worked form distilling a few basic facts ffrom many unreadable achedemic papers (a bit kie doing a jigsaw puzzle with no picture to guide you) and then decided I needed to understand every aspect of this wierd but fascinating technology. It seemed that so much was unkown or explained by techno babble from "experts" selling their machines. It took my about 8 years of experimenting, making mistakes , to discover the many pieces of the jigsaw that finally made sense of this whole technology. It's been a slow process of self education, delving into the edges of physics, cheimstry optics and material science to understand sufficient priciples to glue all the pieces of the jigsaw together. The other big part of the jigswaw that thousands of correspondents helped me to build, was how the whole Chines laser industry worked Helping so many people all around the globe to solve their laser machine problems it was easy to start seeing patterns of fraudlent activity.
So there is no magic solution to my learning. it's just time, reseach , successful and failded experiments. The fortunate thing was my long time interest in video and editing. I decided to dispense withall my semi pro video kit and just do a simple" look over my shoulder "style video.No lighs, no s special mics . no fancy titles etc , just videio as it comes . All facts and no frills I am not seeking an Oscar.
This is a perfectly adequate machine now that I hasve done some work on it the slight jitter you see is very small and whether it be engraving or cutting it is totally unoticeable. Compared to a high quality CNC machne this is still B grade kit but for me, my 5 various laser machines are teaching and reserch aids and not production equipment. On the way to developing my lightweight headI encountered significant "ringing" issues caused bt the head as the nozzle and lens tube acted like a pendulum at the beginning of each scan . It all boiled down to a flexing head mount. Although I have designed several different head mounting brackets, the system I favour most is to bolt the head directly to a 15mm front mounted bearing block....no chance of flex and then all that leaves is what you mentioned, the bearing clearance. So check your mounting flex before investing in a new X rail.
@@SarbarMultimedia Wow! That was a fascinating read for me! Thank you so much! A possible idea to a video of its own - "My journey studying lasers". One thing I wish with your videos is that CZcams were putting at the top of its suggested videos for CO2 laser inquiries (and the like). Often times there is so much value (at least for me) in the videos you make as compared to the top suggested ones.
Well, at least I can tell that mine arrived in a much more useable condition than yours. I bought mine just over an year ago, so would assume the Chinese have improved somewhat.
Yes, the mounting was the first thing to get my suspicion, but I quickly discovered that most of the play was coming from the carriage being lose on the rail. Sure there is flex in the mount bracket, but its contribution I reckon is negligible in comparison to the carriage.
@@DYEngineering
I have to admit to seeing several machines with rubbish X bearings where you just put your finger on the nozzle and with just gentle pressure back and forth tcan feel 0.5 to 1mm of free movement. In all cases , just a replacement bearing ( not the rail) fixed the problem but that is a choice you can make .
I really want to try this on my 100w c02 2 inch lens can you do a short video on how to use the image you provided (254ppi bitmap test pattern) with the dashes with out the theory. I love the theory but i want to just see you do the test. I think that would be very helpful. Thank you from Canda
Hi Mark
It is impossible to get 0.1mm dots from a 2" lens. The best you can expect is 0.2mm dots which means 25.4/0.2=127ppi. BUT even a 0.2mm dot will depend on your tube power and its beam intensity profile. Using a tube at very low power (working in the tube's preionization zone) is the best chance of any succes and then regulating the exposure time with speed. Sadly, the higher ther tube power the less chance of success even with a 0.2mm dot. This is where the 40 to 60 watt tube excels. More power is great for cutting but that power comes at the expense of precision control of low power. The reason for all these "prepare you image for photo engraving" bits of software is that most people do not have the patience or the curiosity to understand to capabilities of their equipment, thus, removing pixels (and lots of detail) is the simple path that most pursue with their machine's 0.5mm dot capability. I have gone into the theory of how and why it is incredibly difficult to achieve a 0.1mm dot and how different materials produce different results. However, all is not lost for you. The second part of photo engraving is to understand how digital graphics works with the eye. Simply put, if you are limited to a 0.2mm dot then every feature in your image will be described with 50% less dots. Double the size of your finished image from A4 (say) to A3 and you have now doubled the number of pixels for each feature. The downside is that this bigger picture looks great at 6 feet away but a bit dotty at 2 feet.
If you can use my test pattern to get dots that just touch on the bottom line then you have 0.2mm dots.. That's the absolute best you will be able to achieve with your machine. This tiger image was done at about 200mm/s and for a glass tube machine the speed is determined by the response time characteristics of you the HV power supply. This is a subject I dig deeply into in another video and discovered that changing my HV power supply allowed me to run the same image at 600mm/s with no loss of quality. See this video if you are interested. czcams.com/video/Cgkze6gPI8M/video.html. It's understanding this sort of process detail that allows me to push the boundaries.
I would love to make a video for you showing how to succeed with your equipment but I absolutley know (1've been there) that I will just be demonstrating failure.
Any experience in photo engraving on Acrylic. I have recently started playing with this (new to me). I have found some strange behaviour. I do the engraving (which of course thanks to your videos became that much better than it used to be) and then cut the outline. As soon as I cut there start to form cracks along the cut edge (but only on the internal, engraved side - not the outside stock), as well as cracks on the engraved surface, as if all the engraved dots form into micro-cracks). This looks almost as if the material had internal stresses and the heat acted as a catalyst in creating those cracks. But then, it's only on the engraved part and not the leftover.
What you descibe is totally abnormal There matybe something deeper happening that you are unaware of. I have worked extensively with acrylic for many years, both cutting and engraving and never encountered such difficulties. This sound like a fascinating problem that may in fact be nothing to do with the acrylic and more to do with your tube. I think we should communicate more on this issue sothat you can send me some pictures etc. CZcams does not allow email addresses and they run algorthms to hunt them down and remove your comment. However they are really stupid and easily fooled by encoding your address in a simple sentence (or sentences) such as this. John will be seeiing DOTty plus a 777 at the big G company next week. Speak soon Russ
@@SarbarMultimedia I guess you can call me as much stupid, since I seem to be fooled by your encoding as well lol. Made a few attempts with the options that make the most sense to me as the correct "decoding", but my mails keep bouncing.
@@DYEngineering
Perhaps those algorthms are wise to my workaround
You can contact me privately via this form
forms.zohopublic.eu/ndeavorlimited/form/K40XtreeemLaserCutterContactRussSadler/formperma/k2Cn0QN5ChpazfTMAUw25lZ-FKpjZa96TQWHjv3ntOg
Hallo Russ. I bought 50w chinese blue white laser. I am trying to find your contact information, but unsuccessfull. I am just curious, do you still offer light head kit for this machine ? I would like to change the mirror mounts and laser head. I have a lots of problems with them, and would like to change them completely on 25mm mirrors and 18 or 20 mm lenses. Thank you in advance for your answer.
Hi Damir
Sadly You tube stpper it's messaging service several years ago. and it will not publish comments with email addresses. Please contact me privately byusing this contact form
forms.zohopublic.eu/ndeavorlimited/form/K40XtreeemLaserCutterContactRussSadler/formperma/k2Cn0QN5ChpazfTMAUw25lZ-FKpjZa96TQWHjv3ntOg
Best wishes
Russ