RDWorks Learning Lab 100 Etching Stainless Steel

[@DustanWebb]

I dont know if you have heard this before but I read somewhere once that you could use a mixture of isopropyl alcohol and plaster of Paris spread thinly onto stainless and it will make it possible to etch it. I have not tried it yet but has always been in the back of my minds projects folder

[@SarbarMultimedia]

Hi Dustin I just answered this and You Tube has posted it into oblivion From what I know about this, it works on the same principle as Cermark and MoS2. It's a thermo chemical reaction with the surface of the stainless and not a melting process Best regards Russ

[@DoRC]

oh man I was hoping to see you run like 3 or 4 passes in a row

[@HeirloomGameCalls]

Hi Russ, I found this lesson extremely interesting as one of my main requests in my shop is to engrave the stainless steel blades of the knives I make. This video proves the concept to be practical for me. when things get settled and I have some more experience, I will have to try this. for now, I will keep reading and watching until my machine gets here. fingers crossed the letters KH do not show up on the tube.

[@SarbarMultimedia]

Hi Please do NOT try to engrave naked stainless as I did in this video. It worked this time BUT take a look at kzbin.info/www/bejne/kHymaXWvmJ2saJo 22min 58 sec and you will understand the trepidation as I undertook this test. If you want to mark steel there is a safe way see kzbin.info/www/bejne/mJCTZ5-Xds-AhsU Good luck with your new machine All best wishes Russ

[@HeirloomGameCalls]

Thankyou for the update. I have been watching as many lessons as possible but given that I am "Retired" I (or my wife) have found so much to do that I seem to be busier than ever.

[@johnstevenson2353]

Instead of Cermark try experimenting by using dry moly spray which is about £12 a tin. I use this all the while for engraving on stainless.

[@stephenbranston1588]

Hi Russ, I am a novice and have just purchased my first Co2 50w machine, I really want to etch/engrave onto stainless steel but am having difficulty finding agents that i can use for bonding in Sweden, do you have any recommendations, I have watched your LBT post, but again unable to buy that product in Sweden. any support will be very much appreciated. BTW, i really do like your videos, so educational.

[@SarbarMultimedia]

Hi Stephen Marking stainless steel is a heat induced chemical process . This video is everything your should NOT do with stainless steel because it will kill lenses faster than you can buy them. All you can do is MARK stainless. Since this making video, I have done more experiments and investigations so you may wish to watch this video. kzbin.info/www/bejne/rZmnop1_nbeEY9E Cermark is VERY expensive but good. There is another product around that you may like to checkout www.engraving-supplies.co.uk/news/laser-marking-products brilliancelaserinks.com/en-gb Also see if you can track down any of these products in Sweden as an alternative to DM-90 www.google.com/search?q=dry+Mos2+spray&rlz=1C1CHBF_en-GBGB911GB911&oq=dry+Mos2+spray&aqs=chrome..69i57.12525j0j7&sourceid=chrome&ie=UTF-8 Best wishes Russ

[@stephenbranston1588]

@@SarbarMultimedia Thank you so much for this video, it has helped me a lot, one last question, do you believe my 50w CO2 laser will be able to mark golf club heads which are primarily made from Carbon Steel?

[@RokyR2011]

Hi, thank you for the video. Informative. Can I ask what type of protective glasses are you using doing this. Searching for affordable solution with my 130w co2 laser. Thanks

[@SarbarMultimedia]

H Rok The answer is nothing more than £2 cheap non prescription reading glasses. There are lots of people that would like you to believe that this laser light is really dangerous. Well, , tt really IS dangerous but ONLY under certain conditions . . The laser beam is about 6mm diameter and like a jet of water from a hose pipe it travels in straight lines and does not create any scattered side rays. In the same way that you can stand right next to a jet of water and not get wet so it is for the laser beam. You need to be standing in the direct path of the beam to sustain any damage, 95% of all materials turn the light energy into heat when it hits the surface. The exception is ANY metal. Metals act like mirrors and will REDIRECT the light. That is why we have metal faced mirrors in the machine. IF the beam happens to reflect AT YOU from a suitably angled METAL surface within the machine (a bit like winning the lottery?) then yes it will HEAT up whatever it contacts. That includes the front of your eyeball, your skin, or your clothes , anything.......... The anything would include protective eyewear , be it glass or polycarbonate lenses. They will absorb the energy and prevent it getting to your eyes. I f you do not wear glasses, cheap polycarbonate protective eyewear will do the job well. see www.ebay.co.uk/itm/Safety-Goggles-Glasses-Eye-Protection-Anti-Fog-Clear-Vent-Unisex-Lab-Work/283847952665?hash=item4216a80919:g:eaAAAOSw59pelnI9 or www.ebay.co.uk/itm/Safety-Goggles-Clear-Safety-Glasses-For-Lab-Work-Dust-Proof-Eyes-Protector/303617649368?hash=item46b105aad8:g:7lwAAOSwov5fBYuw The bigger danger to your eyes is watching the cut when you are cutting organic materials such as wood, There is a VERT intense light (much like a small welding arc) where the beam is cutting. This intense white light contains strong UV spikes which WILL damage your eyes of you watch it for more than a few seconds. You would not stare at the sun so treat your cut zone with the same respect.Again, glass or polycarbonate will absorb the UV frequencies BUT they will NOT attenuate the intensity . It is the BRIGHT light that offers the greatest risk to your eyes. Hope this answers your question. Best wishes Russ

[@RokyR2011]

@@SarbarMultimedia Thank you very much for extended answer. You confirmed my assumption. I'm using two polycarbonate glasses.7€ each. Both of them I tested with direct focused hit of 50W and 0.4s duration. The beam did not penetrate the glasses just a small burn mark on impact side. No damage to cotton wool I putted on eyeball side. Also totally impossible scenario if somebody ask me. If they protected from direct focused hit they for sure can protect from scattered light with extra acrylic protection (lid closed) between glasses and laser. And yes. Totally agree about welding effect. Been there done that 🥺😁. Stronger the "arc" less I look. It works for me that way for few months now. Again thanks for answering. Have a nice day.

[@johnmacdougall9424]

Hi Russ. Just became a (donating) member of RDworkslab! Off topic here, but I have one of these ordered and I'm finding conflicting info re: the size of the machine. I'm also trying to have a cart (trolley?) made up before it arrives. Can you tell me the dimensions and how high you made the cart off the ground? Thanks!

[@SarbarMultimedia]

Hi John Click on the S and the Sarbar Multimedia page should appear. Go to the address bar and add /about to the end of it and enter. You should get a new page with message button top right corner. Send me your email address via that private route and I'll drop you a dxf file of the cart I made (can you read dxf files?) Best regards Russ

[@depravedpuma]

What do you think would happen if you delayed your cutting by .5 seconds? Would it change the structure enough to cut deeper at the same power?

[@SarbarMultimedia]

If you can get enough power into the surface INSTANTLY so that you immediately change the crystal structure of the metal so that it absorbs rather than reflects energy. then you can damage the surface.The melting point of stainless is around1450C and its about 90% reflective. Theorertically that's a big ask .You will notice that it was black cut, that's because it was badly oxidized. I suspect I could have attempted a repeat run and done a bit more damage as the crystal structure of the oxidized material will be different. However with 60 watts, the cut depth will always be limited because the thermal conductivity of the steel will quickly pull the heat away. I spent 10years running a metal cutting laser business and stainless requires some VERY special conditions to cut cleanly and accurately. Knowing what I know aboutcutting stainless made me a bit nervous of even attempting it but no one was more surprised than me about the result. Best regards Russ

[@mryoutuser]

Very nice video, I really appreciate your efforts to educate us, even though some experiments may damage your machine. I have a wood laser machine which works great on wood , why laser won't burn a metal sheet when placed instead of wood? Is it the power, wavelength, laser type ?

[@SarbarMultimedia]

Hi Upon reflection (no pun intended) there is little risk of damage to the lens because when you think about it logically, There is 1.5" back to the lens. and after that distance the beam will have defocused and the energy density will not damage the lens. As I mentioned in the video, the memory of trashing a £500 lens over-rides logic and made me extra cautious. Obviously my machine is not planned to damage metal either. The fact that it does is all to do with something called energy density. The easiest way to explain it is to imagine a sharp pencil, Push the blunt end into the palm of you hand as hard as you can. No pain, no marks. Now turn turn the pencil round and think what would happen if you applied the same force with the sharp point in your palm. Your push forace (watts) applied over a large area (the blunt end) will do little DAMAGE. The same force (watts) applied to a very small area, amplifies it and will do a lot of DAMAGE. The shorter the focal length of the lens, the smaller is the focused spot size. A 2" lens has a spot size twice the size of a 1.5" lens. Hence the largere the spot size the more power you have to throw at it to do the same amount of damage. You will note that I had to run quite slowly so that the heating effect of the beam lingered enough to melt the surface of the metal. Too fast and it wont work. When you work with wood the cutting action is by BURNING. Wood is a very poor conductor of heat so it's easy for the beam to heat and burn it. Metal is a good conductor of heat, so even though I was able to melt a thin layer at the surface, the thermal conductivity quickly sucked the heat from the cut area and limited the depth that I could damage. Different wavelengths will be absorbed by materials differently, especially metals where the absorption is all to do with the crystal structure of the material. CO2 lasers are very powerful but do bump into material limitations. Increasing the power overcomes some of these Hope this has answered your question. Best regards Russ

[@MichaelPaauwe]

Hi Dustin, What you are doing is called temper marking. It's not technically engraving but if it quacks like a duck....

[@SarbarMultimedia]

Hi Michael That's an interesting thought but as I understand it temper marking is something exploited by fibre lasers to produce "coloured " marking of stainless steel. The super precision of power delivery allows accurate spot delivery of temperature to oxidize the surface to one of the range of tempering colours (a very dark browny black to a light yellow) Non -engineers seem amazed that lasers can "paint" colours but fail to recognize that there are no reds or greens in the colour pallet. The process that Dustin is speaking of is a chemical reaction between elements in the plaster and the stainless that only occur when sufficient heat is added to the equation. Sdaly we do not hace adequate control of power in our little fire breathing Chines dragons to achieve temper marking ......but it's an interesting thought that perhaps I ought to experiment with. Thanks for the comment because all comments are thought provoking and who knows where careless thoughts will lead? Best wishes Russ

[@MichaelPaauwe]

Hi Russ, Thanks for all the effort you go to with these videos. I've learned so much from them already. And I've only watched a fraction of them. In my eagerness to contribute something to the conversation, I got your name wrong. Not a great start. Anyway, I've recently got a 150w CO2 laser with 900x600 bed and I'm going through the pain of finding my way around RD Works. So my comment about temper marking was actually in relation to the CO2 laser marking on Stainless. I haven't tried marking any metal yet on my CO2 but I've used an NdYAG laser to mark stainless before. The localised heating causes the color change even if you don't have enough power to melt the surface. Emissivity of Stainless is also higher than most metals at 0.16 so it will absorb quite a bit of infrared. (Ask any kid who's used a stainless slide on a sunny day). The thermal conductivity of stainless is also lower than most other metals. I think that helps to make the markings have very good definition. Your magnified images did appear to show some melting of the surface so you've got enough power. I'm sure you're right that we don't have sufficient control to achieve a particular colour but that doesn't mean we can't make worthwhile black and white marking. Anyway, I should take a leaf out of your book and give it a go, instead of waffling about what should be possible. Thanks again. Mike

[@SarbarMultimedia]

Hi Mike Good luck with your new machine. I hope you are not planning to do much engraving on it because you have bought a fantastic cutting beast (a lumberjacks axe) but if you want to do engraving, you need scalpel control at very low power. Even with my 60 watt tube I sometimes struggle to get the control I need at low wattages. I am amazed at just how much undiscovered territory there is in this simple little Chines dragon and I cant see me running out of subjects ant time soon. Your throw away comment has been added to my long list of things to investigate so thanks for that.. Best regards Russ

[@INWondeR]

I am amazed.. Do you think it's possible with a 2" lens as well?

[@SarbarMultimedia]

Hi I discovered this as I was using a 2" lens but the penetration was minimal even with about 70 watts at the work surface. Running at 2mm/sec may improve penetration but I would guess that anything less than 40 watts at the work surface may not work because the build up of heat (it takes about 1450C to melt stainless) will be overtaken by the thermal conductivity of the steel and the melt temperature will never be attained. Give it a try. Best regards Russ

[@INWondeR]

Luckily I have a 60w, with brand new Si gold plated mirrors mounted (what a difference) So I have suddenly gotten a whole lot more power at the lens. I might give it a try an see if I can do something similar on my machine. :) Thank you for all your wonderful videos, they have really helped me get my laser up and running pretty much perfectly.

[@jimmybleron4700]

Very interesting! Did your lens get damaged at all?

[@SarbarMultimedia]

Hi Jimmy There was no damage to the lens because when you think about it logically, it's 1.5" back to the lens. By that distance the beam will have defocused and the energy density will not damage the lens. As I mentioned in the video, the memory of trashing a £500 lens over-rides logic and made me extra cautious. Best regards Russ

[@ibreakstuff815]

What does your lens look like? did it get impacted?

[@SarbarMultimedia]

Hi Robert I just replied to this comment but You Tube sent it to another universe!!! There was no damage to the lens because when you think about it logically, it's 1.5" back to the lens. By that distance the beam will have defocused and the energy density will not damage the lens. As I mentioned in the video, the memory of trashing a £500 lens over-rides logic. Best regards Russ

[@h4z4rd42]

Awesome experiment, thanks for sharing.

[@robgandy4550]

Just curious, why such high power on that thin of stock. My 40 watt, has to cut at least 5-8mm at 22 mm/s; Also makes total sense why it ingraves.

[@SarbarMultimedia]

Hi Rob It's nothing to do with the thickness of the stock, although the thicker the stock the greater potential for rapid heat transfer to the background. You must understand a couple of fundamental properties of our IR laser beam. Firstly it is a beam of light and carries no heat, just pure energy. A rock falling out of the sky is full of pure kinetic energy but is doing absolutely no damage whilst it is falling. The transfer of energy only occurs when it collides with something solid. The same applies to our laser beam. All molecules are vibrating but the speed and amplitude of that vibration is a definition of their temperature. When IR light collides with a material, one of two things occurs. If that material is a metal then the beam is reflected. The amount of reflection varies with different metals and is nothing to do with the shininess of the surface but all to do with the crystallographic structure. Metals like copper, aluminium, gold and silver are 99%+ efficient at reflecting whereas stainless is about 95%. All non-metals are highly reactive to the IR light and their SURFACE molecules become easily stimulated by the light energy and start to vibrate faster. More vibration=higher temperature. This is the mechanism of energy transfer that occurs in out machines.. The second thing to understand is that the power is not uniformly spread across the beam. The central core of the beam contains the highest energy density. When you pass this beam through a lens, the high energy focused spot you produce is also NOT uniform. There is an ultra high energy concentration at the centre. Bear in mind that with stainless steel, only 5% of the energy is being accepted as a molecular stimulant and the rest reflected. That 5% has to heat the stainless above it's 1450C melting point to cause surface damage. Once the metal is melted, it's crystallographic structure changes and it then accepts the IR stimulation more readily. . But 60 watts is barely enough to scratch the surface. You need kw of energy to cut stainless and I was very surprised that I could raise the energy density high enough to do ANY damage. I was using a 38.1mm focal length lens. If I had tried it with a normal 50.8mm lens with 50% of the energy density potential, I am sure I would have failed. Best wishes Russ

[@duanecalhoon3322]

What would happen if you did the same cut like 3 times in a row???

[@SarbarMultimedia]

The second and third test would be no different except you may not even get to the second test because your lens would already be destroyed. ALL metals are mirrors and in the case of stainless steel it is at least 96% effeicient at refelecting the energy back onto the lens. That energy is sufficiently powerful to burn off the coating that is on the lens. There is an interesting property of firing CO2 light at a metal surface. In its solid state the metal acts like a mirror but IF you can throw enough power to melt the surface, the MOLTEN metal no longer acts like a mirror. instead it absorbs about 60% of the energy to keep the molten state going. The risk to your lens is high so that is why I made this video. I have a few lenses that I was prepared to sacrifice so that you dont try the same thing Berst wishes Russ

[@duanecalhoon3322]

@SarbarMultimedia would you be interested in helping me troubleshoot a electric power problem on my 100w machine?

[@SarbarMultimedia]

@@duanecalhoon3322 It is usually difficult to assist people on an open forum. You tube does not allow emailmaddresses so if you like to contact me via this private contact form I will try to help solve your problem forms.zohopublic.eu/ndeavorlimited/form/K40XtreeemLaserCutterContactRussSadler/formperma/k2Cn0QN5ChpazfTMAUw25lZ-FKpjZa96TQWHjv3ntOg Best wishes Russ

[@duanecalhoon3322]

I contacted you thru the link below, thanks

[@duanecalhoon3322]

It kind of makes me wonder,,,, 90 percent of my engraving is done on stainless steel tumblers, I know the first pass cuts the powder coat but I always do a 2nd or 3rd pass just to clean up the SS after the powdercoating is gone.

[@polakis1975]

What a discovery! Could not imagine this was possible

[@larrykh465]

surface oxidation, if you were to use argon in place of air for the air assist it might come out with a rainbow effect.

[@SarbarMultimedia]

Hi Larry I think the effect your are proposing is the thin film surface OXIDATION effect that occurs as you heat a shiny steel surface. The transparent OXIDE film thickens with temperature and causes interference with different wavelengths of light giving rise to the rainbow effect you describe. This effect happens for each colour at a very specific temperature starting with a faint light straw colour at 176 C and progressing through 7 more recognized colours to grey blue at 371 C. This level of temperature control can be achieved with a fibre laser and you can generate coloured pictures on stainless steel using this phenomenon. However, we stand zero chance of achieving such precision temperature control with our sledge hammer CO2 laser and secondly argon is a shield gas and is specifically used in welding and other processes to prevent OXIDATION. Thus I think logic decrees that argon will prevent the effect you are imagining Nice thought though so thanks for the comment. Best wishes Russ

[@mihaitadici6908]

i engrave RWL34 steel without cermark on a 80w reci tube... i put just painters tape over the knife bland and hit start...

[@Odb718]

After watching more than a few of your videos, I've a theory why your lens didn't pop. The beam was/is askew. Your cutlery project proved that you're not at 100% plum, level, and square. Which in this case was a good thing. I'm betting those more expensive machines were tested meticulously to be. That'd have the laser shooting right back up the tube. Your "3 degrees or so" seems to have a benefit.

[@SarbarMultimedia]

Nice idea but I'm afraid that not the case. The beam has been reset many times between then and now and I am also older and wiser about the peculiarities of cutting acrylic. I was using (and continue to use) a 1.5" focal length lens. I can set my beam absolutely perpendicular to the material surface and still get an off angle cut. Acrylic is unique in that it does not burn or melt, it sublimates when it gets hot enough ie it turns directly from solid to vapour.I should not be able to cut 10mm acrylic with a 1.5" lens but by going slow enough I can. This is due to a light pipe/wave guide/fibre optic phenomenon that occurs where the acrylic traps and reflects the beam inside the cut and causes hot vapour to scarify strange profiles. I will shortly be demonstrating this strange behaviour but please accept that the off angle cut is not through beam alignment. By the way, I thought the same as you originally, it is only time/experience and careful observation that have taught me differently now. If you watch kzbin.info/www/bejne/kHymaXWvmJ2saJo at 22min 50sec you will see what I did to a lens after etching a stainless label earlier in the video.. Basic advice is "don't' try this at home" Thanks for the comment All best wishes Russ

[@rodsims8471]

OMG , 60 watts focus laser head welding a micro bead on mirror polished stainless steel , That WAS BEUTIFUAL !!! and scary at the same time ( pretty gutsy ) Look like great fun . would be cool to see the welds as they were being made , I'm attempting to make a complex acrylic light manifold . and then put it together with optical cement , Humm I may have to look in to just the laser tube , since I already have and X Y plotter .

[@pamelalopez9187]

Hello. i have watched all the tutorials. And more of your videos. I was having a water issue, I fixed it. But now my machine wont cut. It sort of traces the image but wont cut. Any advice? PLEASE

[@SarbarMultimedia]

Hi Pamela It sounds like an almost dead tube BUT lets not panic just yet. A few questions. 1)Do you have an ammeter fitted? 2)Is your tube labeled K H Laser? 3) How long have you had the machine 4) Do you have a small piece of 6 or 8mm acrylic? Speak soon Russ

[@pamelalopez9187]

hello thank you for your reply. It says KH Laser. Is an ammeter like a gauge? If so no i dont. I tried pressing the green test button on the side panel but the laser does not turn colors. BUT if i press the "pulse" button the laser tube turns a strong shade and it looks like purple electricity running through it. I used the power supply from my previous machine and still does the same

[@pamelalopez9187]

i just purchased the machine. i upgraded from a 50Watt blue machine. I accidentally burned the machine and almost my house. So had to buy a new machine. i do not have a piece of acrylic Pam

[@SarbarMultimedia]

Hi Pamela I think it really is bad news. Your machine is almost certainly a machine branded KeHui. The KeHui factory have a notorious reputation derived from all the correspondence I get and some hard evidence I have seen with my own eyes. K H Laser and KeHui (note the similarity) are one and the same. They do NOT manufacture laser tubes. Instead they trawl round all the major tube manufacturers for REJECT tubes. They retest those tubes and relabel those that work "in some way", enough to fool the average technically naive Ebay buyer . They then fit those tube to their own machines. You cannot buy Kehui machines direct from the factory, they ship them in bulk to various warehouses around the world. Lots of private sellers with a PC s (in their kitchens in China) then sell these machines for commission. That way the chain of responsibility back to the factory is broken and you are dealing with someone who knows nothing about the machine and has never seen it. So, I'm afraid from this far away, the circumstantial evidence indicates a dead tube. The fact that your tube glows when you press the pulse button is proof that the power supply is working well, but that glow does not mean that you are producing power. The glow is the nitrogen ionizing but if there is insufficient CO2 in the gas mix then there will be no power. It's a bit like having a car with an engine that works but no wheels..... useless. Depending on where you live I may be able to recommend somewhere to buy a new tube, Do NOT buy from Ebay or Amazon marketplace because you risk buying rubbish I'm sorry it's bad news but once you have experience of a proper tube then I'm sure your tears will turn to smiles. I suffered with TWO crap tubes initially before I learnt my lesson, so I can definitely empathize with you. Best wishes Russ

[@pamelalopez9187]

SarbarMultimedia thank you for your help. I am located in NY USA any idea where I can purchase another one? Or should I just be returning the machine. Which would prob be another headache

[@tim1299]

Great job, as all your videos' . I haven't purchased "yet" a co2 laser. Why? For production reasons . In the US of A sheet goods of acrylic come in dimensions of 48 x 96 inches. A laser from China , being metric, all seem short in any number divisibleby 12, 16, 18, and 24 inches. Question?? Can the axis x and y positive stops' be moved for the purpose of gaining the .25 inchesI need to gain in x and y?. I do not need a machine (for machine footprint and product dimensions reasons) greater than 12 inches x 20 inches or if forced 16 x 24. If possible, would the firmware/software/stepper motors handle the extra travel that would then be created or would the machine parameters be totally "lost". If this has been asked ,excuse the redundancy and please redirect.P.S. just now got connected , not able to ask direct, as yet. through youtube, will check in this lab 100 for your kind response. Thank you , Tim

[@RGCbaseace]

WOW those are beads like stacking dimes really tiny beads outstanding

[@hovedskou]

Hi Russ... Very interesting discovery.. ;-) Did you check the output window in your tube..? I work with very big industrial lasers (up to 10KW), and the biggest risk doing things like this, is a beam reflecting back through the lens and all the way to the resonator. If a (slightly focused) beam goes backwards into the resonator optics it can make quite a big damage.! -Pepsi-

[@SarbarMultimedia]

Hi Pepsi You are right to be concerned with powerful machines such as yours because only a small percentage reflection may still amount to a kilowatt or more arriving back at that tube window. .You note my hesitation in the video, because even with a 3kw machine I have damaged two lenses. Defocused 60watts is not enough to do much damage when you think about it logically, but none the less bad, memories take precedence over logical thought. The good news is that I have done no damage. The fact that the burn was continuous means that all the energy was being expended at the work surface and reflection=0% Best regards Russ

[@thebeststooge]

This will work with all wattages?

[@SarbarMultimedia]

Hi I doubt it . I would guess you need at least 40 watts at the work surface, a 1.5" lens and a VERY slow speed (2mm/sec?). As you increase the power so the speed can increase. It's all to do with energy density and lingering long enough on one spot to melt metal. Bear in mind that metal conducts heat away very quickly so that is what will ultimately limit (or prevent) melting. Best regards Russ

[@thebeststooge]

Exactly what I thought so I am a perplexed at how you managed to cut into it. You call it engraving which is just another word for a shallow cut and with that much metal AND you are not at the precise focal point AND you are using about 55 watts something evil is happening. Black magic is at work here I can tell.

[@guinnesspeaks]

hmmm .. this is good stuff. This tells me that using a 2" lens would actually work better. But that it would be more difficult to focus it. I know you need a longer lens for cutting very thick materials by my own experience. Like for example, I'd have a very difficult time on our 4kw machine cutting 1/2" steel with a 5" lens. But with a 7" it's almost effortless.

[@SarbarMultimedia]

Hi I think not. This is not a cutting exercise but one of local surface damage. In general you are right that longer focal lengths have longer penetration. The problem is that as the focal length increases the spot size at the focus point grows and the energy density (its ability to do damage) decreases. However, you can get the energy density back up by increasing the power. It is energy density that you need for cutting. The longer the focal length the less VARIATION of energy density over a longer length (the beam is more parallel). So provided you have masses of power to play with then you are correct about longer FL=deeper cut. Sadly when you have only 60 watts you need it to be amplified as much as possible to do damage. A 2" lens has twice as much spot AREA and will therefore have HALF the energy density of a 1.5" lens at the focus point. Best regards Russ

[@guinnesspeaks]

Damn .. that really does make a lot of sense.

[@guinnesspeaks]

also ... the shorter focal length increases the reflectivity wider. Decreasing need to worry about lens damage. ( as if that is a concern at 60 watts)

[@guinnesspeaks]

This being the case ... a 1" lens would be better. does that even exist for these machines?

[@malcolmbarth1605]

I am interested in this as I am in the process of getting a large 150W 2.5m x 1.3m machine from china. Its only about $6000USD landed. I could have obtained at an extra $3000USD one that would cut up to 1.5mm stainless. As far as I could see the difference was a lens system that would electronically track the surface of the stainless very well. Looks like it uses a 1.5" lens. So I suspect you machine may cut 0.5" stainless.

[@SarbarMultimedia]

Hi Malcolm For 12 years I ran a metal cutting laser business with two 3kw machines so I thought that owning one of these low power sealed tube Chinese machines would be an easy hobby for me to retire with. Not so. Maybe 5% of my knowledge and experience is transferable. After 2 years I am still learning!! However, metal cutting with these machines is not a simple matter of a different sensing head. The tracking head is essential to maintain focus but there is a lot more than that that is not mentioned when you look at yYou Tube videos or machine specs. Although You can make a reasonable job of cutting mild steel with just ordinary air assist you will need much more pressure maybe 15 to 20psi (big compressor!!!) The ideal requirement for efficient cutting of mild steel is pure oxygen (expensive) at about 10psi. Stainless is a completely different animal. If you start cutting stainless with any oxygen around the melt turns into treacle and becomes very difficult to blow out of the cut area. For that reason you use pure nitrogen BUT it has to be used at very high pressure (120 to 150 psi) so that's a hideous amount of gas consumption (and expense). Metal cutting is not really a hobby, there is so much cost involved with infrastructure that it has to be a high turnover business to recover the costs. If you listen to any you tube videos you will hear the hiss of high pressure assist gas. Go and visit a laser profiling facility and you will see just whats involved. I was surprised that I could get enough energy density with 60 watts to damage the surface of stainless,. The black cut is great for marking but tells me that the melt was very oxidized. Best regards Russ

[@raewebb6348]

Yes that is what I thought to. I also expected a assist gas as maybe these need this but look at keliangcnclaser.com/5-laser-cutting-machine/216293 this is the one I looked at buying and lists stainless up to 1.5mm stainless in its cutting list with a 150W Reci tube. I decided in the end to get the wood only version with a 150W Reci tube. I already have a 600x400mm desktop laser from them with a 60W Reci tube that goes well. I wanted something that I could make furnature on :-). like you I am getting these for fun, retirement and to allow the local's to come and use them at a very low price. www.thedoylestonshed.nz

[@raewebb6348]

ops Rae webb is my partner. regards Malcolm.

[@SarbarMultimedia]

Hi Malcolm. You will probably need your 60 watt machine for engraving projects where you need relatively low power. I was recently using a supposed 100watt reci tube (it was a W2 and inreality was only an 80 watt output) but with a 2" lens was ablle to cut 3/4" oak at 5mm.sec. A 4" lens and 150 watts will do even better. I'm sure you made the right choice. Best wishes Russ

[@ashleybishton742]

Could you laser cut some catapult designs for me so that I can use them as tamplate. Il pay you for them I want as many as you can find and complete.

[@SarbarMultimedia]

Hi Ashley Sorry to disappoint but I am not using my machine for monetary gain. I quit manufacturing a few years ago and now just use it as a learning vehicle for my own personal enjoyment. However, there is a facebook group where you can request help from a large group of entusiats facebook.com/groups/900528680076062/ All best wishes Russ

[@RickEverett]

Hi Russ. Have been doing some experimenting myself with some 52 rockwell spacers. The thickness of the spacers is critical, as they are to be ground to tenths of an inch, (.0001) thickness. The OD however has a higher tolerance. We then use an engraver tool to label each piece with the part # and it's thickness. When you have an order for 100 pcs or more, the hands get tired from engraving by hand. Spoke with the boss and took one home to experiment with the material, thinking its 4340 (Unsure) hardened to 52 rockwell. Went with the bonding route, at 50% power, using dry molly spray, (Get to use my rotary as well) and it came out with a nice "Digital" finish of all info. (Scans in under 40 seconds/Piece, saves your hands) Although I'm thinking 60% might brandish a better result, so i'll keep testing. I have also been doing stainless water bottles, using the Dry molly spray and 16%power, with acceptable results. That said, this is very interesting, being able to physically alter the material itself! I also think it shouldn't damage the lens as it has to travel back TO the lens the same distance, after reflecting, and thus shouldn't have the power to damage the lens, right? Seriously!....What a great hobby!

[@SarbarMultimedia]

Hi Rick My previous bad experience was over riding the logic of the situation. I reasoned that IF the beam was reflecting, it would be in a divergent form. A 60 watt diffuse beam is not going to do any significant damage, but of course, as soon as you see the bright light of the melt then you know that the energy is going into the surface and not reflecting. I have tried dry moly many times and it does a good job. Slower speed more power allows the beam to linger a bit longer to achieve a good thermo chemical bond. One must not ignore the mass of the object you are marking because the thermal conductivity of the body is trying to drag the heat from the marking zone. Thicker material requires more power/slower speed Best wishes Russ

[@RickEverett]

"A 60 watt diffuse beam is not going to do any significant damage, but of course, as soon as you see the bright light of the melt then you know that the energy is going into the surface and not reflecting." This makes total sense now. Brilliant, Russ. Thanks for all the great info. Rick

[@guinnesspeaks]

Ok ... so with this proven. I watched your other etching experiment in SS with the special paint. I can't help but wonder why those were so disappointing ( extra expense aside) This is a focal/travel speed issue at that point?

[@guinnesspeaks]

I mean a 2" lens would improve the etch quality because in that format, you could regulate the heat better for the ceramic stuff to bond.

[@SarbarMultimedia]

Hi This method of etching is completely different. It is not a surface damage process. It is a thermo chemical reaction on the surface of the stainless. It still requires a certain level of heat at the surface for that reaction to occur. If you do not get the balance of power and speed correct, the thermal conductivity of the steel will pull the heat away from the work area. The thicker the material you try to mark, the slower (even with more power) you have to run Best regards Russ.

[@SarbarMultimedia]

A 2" lens has half the energy density of a 1.5" lens so you would have to double the power or halve the speed to achieve the same heating effect Regards Russ

[@guinnesspeaks]

I'd like to send you a cad file or perhaps a pdf if you prefer on exactly my thoughts about this ... Do you have a place from to send you file that won't affect your daily biz by making it public?

[@guinnesspeaks]

My thoughts are about the heating process , not about the surface damage. It seems to me that a longer focal range would provide a more consistent and reliable embossing through the entire plate using the paint. Not just one section of it. During your test burns using the paint, some etching caused warping to the material. The material moves and changes the focal point to the surface. Given that the goal in that method is not to cause surface damage, but to create a chemical bond, a longer focal range would be preferable. It seems that if you have the power to cause surface damage, you'd have the power to heat a chemical reaction, and to do that over the surface of a larger plate, (nobody has a perfectly level bed) you would prefer a longer focal range. The goal would be to not cause surface damage, but to evenly heat. Hair dryer versus a blow torch.

[@marshalltjones]

I think what may be going on here is that steel is a VERY poor conductor of heat compared to aluminum and copper alloys. Since the heat does not flow away, you may be getting it hot enough to affect the surface. You should pop that thing in a Scanning Electron Microscope!

[@SarbarMultimedia]

Hi Marshal You are correct about the lower thermal conductivity of stainless but it also has a lower reflectivity of about 95% when compared to that of gold, silver copper and aluminium which are at 99% plus. For stainless this means there is 5% light interacting with the surface molecules of the stainless. 5% may not seem much but with a 1.5" lens and full 70 watts there is so much energy density in a spot about 0.1mm diameter that 5% is enough to stimulate the molecules above their melting point. Once the metal has melted, it's crystallographic structure changes and it no longer reflects the light. However, there is not enough net energy to cut the material. just enough to melt a few microns deep. That melt material is cooling in the presence of oxygen in the air and its the black oxide layer we can observe. The BIG risk with this experiment was the 95% reflected light. Several people have postulated that the reflected light will be harmless to the lens because it will reflect off the surface the opposite way to the converging focused beam. I'm pretty sure this is wrong because I have damaged a few very expensive lenses experimenting with cutting aluminium and copper on 3kw metal cutting lasers. The light is not reflecting off the flatish surface but off the crystallographic structure of the material and I think that instead of harmlessly diverging and scattering off the imagined reflective flat surface there is a colimating effect from the crystal structure. If this is the case then then add into the mix addition and subtraction of colliding wavelengths and the energy that gets reflected back to the lens would easily be high enough to burn off the anti reflective coating on the lens. Having "got away" with it for this experiment, my luck ran out when In tried it again on another occasion . see kzbin.info/www/bejne/kHymaXWvmJ2saJo at about 28minutes Best wishes Russ ps My scanning electron microscope is tossed up in the attic because the wife was complaining about it cluttering her kitchen!! Big smile. This is shed science not NASA

[@marshalltjones]

SarbarMultimedia Well, I work for the Navy....have one at work

[@steven-jellemeijer8412]

CO2 laser?

[@SarbarMultimedia]

Hi Steven Yes, a CO2 laser where the wavelength is 10.6microns .Having spent 10 years owning two 3kw CO2 lasers as part of a sheet metal business, I know the difficulties of cutting stainless steel with a CO2 laser. I was VERY surprised to find I could reach an adequate energy density with just 60 watts to melt the surface sufficient to mark it. Seeing is believing. Best regards Russ

[@Runner50783]

mmm, engraving is the first thing that comes to mind

[@SarbarMultimedia]

Hi Abraham Simple line engraving (cut mode) will be possible but scanning will be painfully slow and I suspect it will distort a flat plate because stainless has a tendency to do that. It has to be slow because you need the energy to linger on one spot to melt it. I'm still amazed that it did it. The effect with the Bodor 2" lens was not as pronounced , but the potential to mark the surface piqued my curiosity. Best regards Russ

[@SarbarMultimedia]

Hi Abraham I have a question for you this time. I know that you were considering changing your steppers to servos. Did you ever do it? I presume that you used hybrid servos which technically are steppers with closed loop positional feedback. I have another correspondent that is convinced that his acrylic striations are caused by his steppers and is planning to change to servos. I am in the enviable position of having two machines. one with servos and one with steppers. If I showed you edge samples from each you would not see any discernable edge difference. If you have servos, did it fix the edge striations on acrylic (apart from running slow to flame polish the edges).? All best wishes Russ

[@Runner50783]

Hi Ross, eager to share my experiences with you. Servos have been the single most radical change I did to my machine yet and its been absolutely worth it. Just to give you an idea my current acceleration parameters are 2000 mm/s^2 min and 8000 mm/s^2 max when cutting, for engraving I use 30 000 mm/s^2 on the X axis, that translates into no less than 3X the avg. cutting speed on papers and thin materials. This to me are far more important than the maximun speed you set the cut to, specially on intricate cuts all with very little deviations (oscillations, striations, etc...) and I can go higher but then I will compromise the actual structure of the drive system (bearings, bolts, nuts, etc...) that my cutter came with from factory. Now, I'm using true servos, Teknic's ClearPaths to be precise and in theory they are far superior to leadshine's EasyServos that came with your newer cutter, the feature that I think makes all of the difference is what they call Jerk Limiting, this is like a cushion on your drive system as it smooths the motion profile at the beginning and the end of the command (acceleration and deceleration) reducing the stress on your drive system allowing you to achieve much higher acceleration rates with out pulverising your cutter. Adapting them to my machine was no easy task (as Teknic's promo videos may make one believe), but after properly tuning them to my machine they are a dream that is translating into real economic benefits on my case :)

[@Runner50783]

On the acrylic issue, did not you debunk that a while ago?, I still have them if that is the concern. Stiations on other materials like paper and wood did go away yes, but on acrylic, its a whole different thing

[@ВикторШестакович]

дуже вражае, super!!

[@SarbarMultimedia]

As I anticipated, this experiment burnt the anti-reflective coating off the underside of the lens. Yes, there is enough power to melt the surface but as I say in the video, I knew this was a risk. These lenses are only $15 and I could sacrifice a lens to show you what NOT to do and why. I know you may be amazed at the result but DON'T try etching RAW metal, always cover it with something. You might like to view this unpublished video of marking stainless steel. kzbin.info/www/bejne/eIjSkJSrZrmDgpI Best wishes Russ