Air assist myths

[@MalcolmProductions1]

Excellent discourse on supplementary air, I just bought a co2 machine and set it up with a solenoid for my compressor but have the internal pump running in bypass around the solenoid as I want air running all the time to protect the lens. I was thinking of getting a larger compressor, but now will consider a second larger volume air pump to supplement the original one with a relay to turn it on with lightburn. I'll see how things go as I'm just getting started.

[@paulsangree916]

To completely eliminate the flow restriction of the solenoid valve, an alternative is a “full-flow motorized ball valve”. “Full flow”means that the valve orifice is the same diameter as the input and output fittings, so flow restriction is minimized. In the USA the most common air hose used on shop compressors is 3/8 inch with 1/4 inch fittings, so the valve only needs to be a 1/4 inch valve for our purposes. Motorized valves are actuated using an electric motor and gears. They have an added advantage that they draw only a minuscule amount of power when not actively opening or closing the valve. There are multiple versions with different ways of controlling the valve, but for our application the “2-wire auto return” version probably is the simplest. With this type you simply apply power to open the valve (assuming it is normally closed), and disconnect power to close it. The valve contains a circuit that stores enough power in a capacitor so that it can run the motor long enough to close the valve after power was disconnected, even in the event of an unexpected power failure. There are a couple of brands on Amazon: “US Solid” and “Kezhai Dream”, both made in China.The US Solid one has some plastic gears but the more expensive one has all metal gears. Both of them can be driven using 9 to 24 Vdc.

[@SarbarMultimedia]

Thanks for your detailed list of valve options. I will examine those valves on Amazon because all knowledge is good knowledge and I have not encountered these brands before. However no matter how "full bore" a valve is, the limiting flow resistance is either the fitting into the nozzle or the orifice in the nozzle itself. There can be no less resistance than removing the valve all together, which I have done for test purposes. The free airflow from the nozzle that I see on my flow meter is little different. The disadvantage of any motorized system is response time. One of the air assist options available on my RDC 6445 controller is to have the valve opering with the beam on and off. A poppet solenioid has about a 10 ms response and can match the laser switching. If you just want to select air on or off for a layer where switching only happens once. then slower response options work well enough.

[@swp466]

This is something I've been saying for years as I see these people recommending shop air compressors for their lasers. Not to mention the addition of moisture to the air stream from condensation in the storage tank. Knowing that flow is more important than pressure, what would you say the optimum flow (in CFM or LPM)? And, would the optimum flow rate be different for different materials (wood, acrylic, etc.)?

[@VladOnEarth]

I machined a custom orifice plug for my machine and it works MUCH better now. What I did basically is reduced orifice from 4.2mm to 2.5mm, so the pressure is increased, flow is same, and it helps with much cleaner cuts now. It depends on material, I cut and engrave a lot of EVA foam and rubbers, so these benefits of higher pressure are more apparent of such materials. More flow will never hurt, which is why I upgraded my machine with 180W 8inch exhaust fan too :) When I tried my shop compressor tho, it was a disaster due to moisture build uo, totallly unnecessary.

[@SarbarMultimedia]

Hi Steve Now you are getting a bittechnical!!! As I demonstrated, if you keep the gap between work and nozzle small (2 to 3mm) and you use a dedicated cutting nozzle (2mm to 2.5mm diameter orifice) then it requires very little flow to efficiently purge fumes from the kerf. My experience is the anywhere between 6 and 10 LPM should suffice You must remember that most compressors are rated at CFM or LPM free air . My little pump is rated at 70 LPM and that would be true if you measured the volume directly out of the pump with zero restriction. into free air. As soon as you start restricting the flow in some way, the pressure starts to increase and the flow decreases. This is a very non-linear relationship. . My pumps are rated at 0.3 bar max pressure (4psi) so my zero flow reading of 3.5psi is not far off. There has to be a pressure difference to create flow and just like elctricity, if you wish to incease the curent FLOW though a resistor you must increase the voltage difference (ie the pressure difference). Many lasers are supplied with a nozzle that has a 4mm diameter orifice. This is basically good for neither cutting nor engraving and shows a total lack of process understanding on the part of the Chinerse machine builders. There is no optimum flow rate for different materials . Any wood based product chemically degrades upon exposuer to the laser beam (that's a whole differnt topic) and produces a mix of gases plus a variety of solid and liquid micro particlates which when suspended in air we see as white fumes. These micro particles absorb laser energy and make the cutting process less efficient hence the aim of air assist is to quickly push those particles out of the BOTTOM of the cut as soon as they are created. to keep the cutting as efficient as possible and stop those fumes settling around the edge of the kerf. Brown edges to the cut indicates inefficient or biassed.air assist. (the subject of a future video) Acrylic is a unique material in that is the only material we can cut that does not chemically degrade during cutting. It turns to liquid at 160 C and then boils and evaporates at 200C. So cutting is by vapourization not chemical destruction. Just like steam. the vapour micro particles will still absorb laser energy, heat up even more and then chemically decompose to produce flammable gasses.. So air assist will help to purge the vapour, dilute it and move it away from the laser beam so that it does not ignite.. if you haven't seen it already you may like to watch kzbin.info/www/bejne/m5Ldao17n9ydnNU Best wishes Russ

[@swp466]

@@SarbarMultimedia Thanks for the detailed reply, Russ! I have seen the honeycomb video as well, and I only use my honeycomb when cutting paper -- never with wood, acrylic or foam. I've been wanting to add a flowmeter like the one in your video for quite a while now, and you just pushed me over the edge -- I just ordered a Dwyer 1-20 lpm flowmeter with valve so I can tweak the flow. As for the nozzle, I use the American Photonics lens kit for my boss laser. I'm not home to measure the aperture, but it is very small. Their lens kit has the focus lenses permanently mounted in the tube, so you change out the whole tube for different focal points. But they all share the same 10.5mm gap between the material and nozzle, so setting the focus distance between the nozzle and material is as simple as spacing the nozzle with an AAA battery. I don't think I can post non-KZbin links in comments, but Google "american photonics boss kit" I'm referencing. Cheers, Steve

[@resin-art-and-3d-printing]

Thank you for explaining how air assist works. I have just recently got into laser engraving with a small 5.5 Watt Diode laser and was going to buy an air assist, but for a pump with tubing and the fixings they are not cheap. Lucky my laser came with the side mount for an air assist so instead of paying stupid amounts of money I have purchased an aquarium pump which has the same flow rate as they ones they are selling for laser engravers and cutters and does the exact same thing for a lot less money and your video just proves this. Its all about the flow rate not the PSI ..

[@SarbarMultimedia]

A 5 watt diode laser is really only suitable for engraving Cutting with multiple passes tells you how inefficient it is at cutting. You do not need air assist for engraving because the last thing you want is to blow the brown fumes onto your work. You need to let them explode upwards and BLOW then away with crossflow air The only reasin for air assist is to keep a SMALL amount of positive pressure in the nozzle to prevent lens contamination by the fumes. Your beam is blue but you can clearly see the fumes in your beam. Point your air assist tube parallel to the work sirface where the beam hits and see the difference to the smoke in your beam.

[@resin-art-and-3d-printing]

Thank you for the reply. Im new to lasers and this info really helps. I will do some cutting but only 3 mm ply so will use the pump for that only. I will also more than likley upgrade to a 20 watt at some point but I did not want to spend a lot of money on my first laser to find out that im not going to use it much. I really do appricate your advice thank you

[@SarbarMultimedia]

Diode laserrs are a simple way into the laser technology world and with no mirrors to worry about or coolong systems it is a tempting first step and the world of light is fascinating when you turn that light into a sort of optical tsunami to damage materials by virtue of its INTENSITY.. However, different wavlengths of light affect materials very differently. The long wavlength CO2 technology can damage many more materials more agressively than the 450nm diode technology. So think carefully about spending lots of money on a more powerful diode. machine when an equally priced CO2 will outperform any diode. I have never spent any time with a diode laser because they are so limited. However in the next few months I do plan to fit a range of diode heads to one of my CO2 machines (obvously disabling the CO2system) so that I can explore the technology in a way that most cannot because the diode control technology is in itself specialised and limited.,@@resin-art-and-3d-printing

[@resin-art-and-3d-printing]

I will keep an eye for your videos when you explore the diode laser technology :)

[@magichousestudio]

an essential video to understand air assist! Thank you very much for all the tips. I was able to buy a small 60Lmin compressor which does the job just as well as a huge compressor that consumes electricity and is much noisier. for me one of the best videos on the subject. thanks again

[@joshsmallwood1]

I’ve been playing with my air assist a little. I have a question, as you were saying in the video, engraving requires less air. Would you ever engrave leather without air assist? I have the stock air system. So I really don’t have the ability to lower my air pressure for engravings. But I’ve tried engraving without air and my work does look darker and better.

[@SarbarMultimedia]

Hi Josh Leather is a particularly "messy" material to engrave because of all the oils in the hide. Thr copious volumes of tar laden fumes represents a serious issue of tainting your work with sticky brown residue. The slow mo images I show about "explosive " fumes spresding sideways for wood engraving are the same (but worse) for leather. Although the general rules for engraving and cutting are as I descibe, there are a mix of techniques that work well for leather and all organic materials., First see this little video I created for a guy that wanted to cut, draw and engrave with one setting, one nozzle amd achieve a clean residue free finish.. kzbin.info/www/bejne/fqi5qJKKr956qK8 Note the BIG air gap that allows the fumes to escape upwards The fundamental issue with leather engraving ids depth of engraving. If youb watch this video you will see me illustrate that there is no such thing as an "engraving" lens . All lenses are cutting tools and convert copious amounts of SOLID material into FUMES.. That is the problem with engraving, even though you may be engraving quickly the mass of fume creation is your enemy. I have developed a technique that greatly reduces the rate of fume creation......convert images to dithered bitmaps see this video kzbin.info/www/bejne/i2S4kJSKmrp0fNU Best wishes Russ

[@ianstewart-koster9982]

Thanks, Russ. You basically explain what I've always tried to tell people - it's not about pressure, and having a huge flow rate at some higher pressure can blow the substrate sideways and wreck a job too. But I learned something interesting: somehow the air press-fit end connector at the nozzle caught fire, and melted before i saw it, 6 months ago. Before I could get another one, I left the air hose hanging loosely, which it did, dangling down and almost horizontally below the nozzle. I kept running it, and it was brilliant. The little chinese puffer pump was blowing the smoke away from the beam area almost better than when it blew down through the nozzle. After thinking for a bit, I bought some tee pieces and regulator screws, to divide the airline at the nozzle so I can have some air coming through the nozzle to keep debris out, and some blowing past it underneath like I found to me most helpful. But I've had scant need to use the laser since I got the tee pieces - other priorities took over.

[@SarbarMultimedia]

Hi Ian I know you commented on this video but in kzbin.info/www/bejne/bWq5i52Dmct1o6s at 45:25 I demonstrate the crossflow air assist that you accidently discovered. Great for engraving but useless for cutting.I have experimented with quite a few different air assist methods and I will soon put together a video to demonstrate the sucesses and failures of my wacky ideas. Inquisitiveness and failure are the basic ingredients of success. . Best wishes.....Russ Russ

[@ianstewart-koster9982]

@@SarbarMultimedia thanks , Russ! Trial, and error, and further trial... your words are more eloquent than mine!

[@LithosAndLasers]

Always and informative and entertaining explanation. Thanks!

[@tof545557]

Hello ! Thank you very much for your video ! I have ordered the Cloudray system with the solenoid valve kit on Amazon yesterday, but can you tell me what is the size for your stock air pump please ? Mine is ACO-003 / 45 Watts / 50 liters by minute (delivered with a 50 Watts CO2 chinese machine). I understood she's sufficient but if I buy an other with more liters by minute , for exemple 100 or 150 what will be the differences ? Thank you for your answer, regards, Christophe.

[@SarbarMultimedia]

Hi Christophe Air assist pumps are widely misunderstood Take a look at the list of popular Hailea ACO compressos at this website gogrow.co.uk/products/air-compressors-aco-series-high-frequency-hailea It does not show your ACO-003 but it shows something very important......... PRESSURE The final goal of air assist is to remove the smoke fumes as efficiently as possible from the cut zone in the kerf. It is a VERY small slot you are trying to direct air into and you need to do that as EFFICIENTLY as possible. People intuitively believe that more flow means better air assist. Sdalythat's not how the physics of gas flows operates. Somewhere in your air systen there will be a limiting diameter for the FLOW. That mayb the 2.5mm hole in the end of your nozzle (idealy that should be your limiting restriction) or it may be the size of the passage through the fitting into your nozzle Wherever that restriction happens to be will govern the FLOW of air. However, you can force more airflow through that restiction with a higher pressure. As this video shows, you do not need a high volume pump but you need sufficient flow and pressure to allow a 8 to 12 litres per minute through your nozzle. Increasing the pump size is a waste of money and also inceased electricity usage. I have 70 l/m pumps on my machines and that is more than enough. Examine HOW you are using your air assist to make sure you are getting the maximum efficiency from what you have . Take a look at this earlier video I did about how airr asisst actually works and the way to maximise it's effect. kzbin.info/www/bejne/bWq5i52Dmct1o6s Best wishes Russ

[@terryevans1976]

Great information as always Russ

[@aus1046]

Can you help me to understand why I need a big nozzle for optimal engraving? I'm using the cloud ray compound lens kit and if I recall correctly the nozzle diameter isn't that large. Should I drill it out to be larger?

[@SarbarMultimedia]

When you fire the laser beam at material (especially organic materials) you vapourise small volumes o SOLID material and rapidly create a huge volume of fumes. It's the same as when half a cupmcof water boils into a HUGE volume of steam so as fill a closed room in minutes.. When you CUT material you blow the fumes out of the bottom of the cut with a small orifice nozzle to to create well directed efficient air flow through the kerf. Engraving is different. The only place fumes can go is upwards. If you have a big gap then the fumes "explode" upwards abd the tarry resinous fumes do not affect the surface of your engraving. If you use a small orifice nozzle for engraving , even small air flows will be directed down and force some of those resinous fumes back onto your work. The compound lens already has as a large hole (about 6mm diameter) so as to slow the airflow from the nozzle and prevent it "jetting" air at the work . There should be just a whisper of air from the nozzle to stop the lens being "smoked" and the airflow should not be strong enough to blow the resinous fumes onto your work.. Best wishes Russ

[@samlenlap]

21:32 can anyone tell me what is that and is it better than the pump that comes with machine

[@SarbarMultimedia]

Hi I bought this from Amazon www.amazon.co.uk/Oil-Less-Disinfection-Equipment-adsorption-Automation/dp/B07WP47P6G. Yes it delivers higher pressure but the smaller diaphragm works hardet than the one supplied withthe machine but the air is hot and the pump is noisy. . I used this as an example and not a recommendation. Stick with your original pump.

[@samlenlap]

@@SarbarMultimedia I currently use high pressure pump as u showed in video With closed line pressure set to 30 psi. I was going to add one more machine to our workshop, for that I was going to buy a new compressor but after watching this i have second thoughts

[@samlenlap]

@@SarbarMultimedia I use my machine for continuous cutting, speed is important and for that when I switched from regular pump to air compressor there was significant difference

[@SarbarMultimedia]

@@samlenlap Hi I have heard reports that higher pressure (actually means higher flow rate through the nozzle) gives more efficient cutting. I have done many experiments and not been able to find this improvement. However, I have never been able to obtain data about the systems that claim this improvement. Can you let me know what lens you use, what is the airgap between nozzle and work and what size is the hole in the end of your nozzle. Many thanks Russ

[@samlenlap]

@@SarbarMultimedia my lense is 75 mm Distance from nozel to surface 7 mm Hole at bottom is around 2 mm Also I have 100 watt tube For cutting 3.4 mm mdf I use 55% Power and 33 cutting Today I tried using less air flow cutting was successful but it left some extra resude as compared to high flow air setting Also tried the small pump it had significant flow and pressure loss at end of nozzle as compared to the beginning of pump I have 1 hp pump 50 liter tank size compressor For my next machine I am thinking about 1hp pump and smaller tank may be 20 liters as flow is all I want Please correct me if i am wrong

[@archerak293]

I liked the addition of this video with the one that previously you showed the need for only light air on engrave but higher air on cutting. It might be interesting to see what the differences are in cutting at some intervals of air flow keeping all other things the same. Also I believe from your testing having the gap between the nozzle and the workpiece shorter seems to help some also. I spoke with someone that runs a laser that cuts metal and he stated their gap between the material and the nozzle is very close. It would be interesting to see another video on dealing with the nozzle gap too. That head you have is really cool in that you are able to so easily swap lenses. Now you have me thinking how I can test some of these things on my setup.

[@SarbarMultimedia]

Hi The nozzle spacing for engraving and cutting is logical but sometimes you need to do things that are not logical . See ths video I did for another guy with air assist issues. It may set you thinking. kzbin.info/www/bejne/fqi5qJKKr956qK8 Best wishes Russ

[@williesims8655]

So I am actually dealing with the air assist issues now, I have a machine that when new costed about 20k. It's an engraving machine using an RF Tube, it doesn't have a through nozzle air flow, but instead it uses an air knife, a small pipe runs along the x axis that blows air across the engraving area at slight angle that deflects up off the surface moving the smoke up and away from the work

[@SarbarMultimedia]

Hi I have 3 C02 machines , and RF machine and a fibre laser. The RF laser has been good at high speed engraving but never shown any serious cutting capability, even with a coaxil air assist through the nozzle.. Yes, it cuts but is no competition for the glass tube machines. So I can understand why you call it an engraving machine. After years of badmouthing the unreliability, short like span and crap performance of sealed glass tube technology, it is notable that Trotec is now selling a combined technology machine as the best thing since sliced bread. Hmmmm. I have experimented with this air knife principle myself as one of many ways to use air assist and it works well for engraving but is utterly uselessm as a cutting aid. The micro particles produced when cutting wood and acrylic absorb the laser energy and reduce cutting efficiency. The only way to track cutting and blow the fumes out of the BOTTOM of the cut is with an air flow that is coaxial with the laser beam. I have seen many videos of Epilog and Trotec machines using this air knife princple and the cuts are a brown mess around the kerf edges. They offer all sorts of "hacks" to remove the "burn" as they call it, as a post processing operation.. Some later macines have a nozzle( of sorts) but it is certainly not a cutting nozzle as I show in this video. Out of personal interest, on the output of your RF unit I would expect to see a beam expander tube. I would be interested to know if this is an X2, X3 or X4 unit. Mant thanks.

[@williesims8655]

This is a 20 year old machine it is a Xenetech, I am.updating.the electronics to a Ruida Board, like you I question its ability to cut well, the laser source will be back from the recharge shop Monday and I will start doing some testing

[@williesims8655]

P.S I also have an 50 watt fiber laser source that I want to run through a gantry system to cut thin metal with I would love to pick your brain on the design ideas

[@SarbarMultimedia]

@@williesims8655 Hi Willie To fit a fibre laser laser head to a moving XY plotter machine may prove to be challenging. Not mechanically, but from the point of fibre flexibility . Yes the fibre cable is flexible but not designed for continuous flexing.. It's for that reason that fibre lasers normally work via a galvo head where the mirrors move and the fibre optic cable is static.. The problem could be reduced if you mount the laser source on the gantry and limit the X axis to maybe 200mm. This would limit the flex on the fibre cable which can be several meters long. However, a 50 watt fibre laser is pretty powerful and may require speeds in excess of 200mm/s. . That then becomes a mechanical challenge to create a stiff gantry and provide sufficient motor torque to accelerate the massquickly to cutting speed.. I would be happy to bat ideas around so if you wish to contact me privately use this contact form. forms.zohopublic.eu/ndeavorlimited/form/K40XtreeemLaserCutterContactRussSadler/formperma/k2Cn0QN5ChpazfTMAUw25lZ-FKpjZa96TQWHjv3ntOg Best wishes...Russ

[@nickynorton]

Pretty well matches the testing I did a few years back With a $300 compressor and two Aquarium pumps 1 pump 20 l/min the other 70 l/min I actually used an air pump needle 1 mm from cut zone The 70 l/min Aquarium pump gave the best results ($58 CA) 18 watt By fiddling with the Air Compressor I could get the same results as the 70 l/min pump BUT the noise and co$t to run it absurd 900 watts AND the power surges when it first kicked on were bad...It needed to be on its own circuit I might also add when doing NWT using air assist will reduce the TiO2 reaction and give you greys and Not Blacks The same when engraving wood ...with air assist on the wood "burn " is not as dark In the above two cases I will have the air assist nozzle Blowing across the lens to keep it cleaner

[@ianbedwell4871]

Interesting video as always. I used a different setup, 80 PSI to a air dry and regulator mounted on the side of the laser. Then a custom turned head that reduced the air gap between the nozzle and the material (longer and finer than the standard). It had dual air feeds to the head. It made a large difference to the quality of the cut. I agree its all about flow not pressure. I had a large range of settings for different types of work and material, the regulator on the laser was used not the one on the compressor to change setting. An air dryer is critical otherwise moist compressed air can wreck the cut. In NZ in summer the humidity is very high. Liked your water jar demo, that was my theory about closing the distance to the material by the use of a longer head with 2mm hole. However you need very good alignment with a smaller hole. I disagree somewhat with the engraving setup, a longer focal point allows a finer engrave. Commercial reality trades time vs cost. So doing a job with much less cleanup (and my engraves had almost zero brown sticky stuff) and faster means I can do more work in the same time. Material choice (which is a massive subject on its own) also makes a major difference.

[@semperidem2577]

One thing to add.... Compressors usually have a 'duty cycle' which means that they cannot be run constantly and need a ceratin amount of time to recover and cool down. Most lower end compressors, the type that most people would use with a laser, will often have a duty cycle as low as 25%. So if you run the compressor for 15 mins say, then you should let it rest for 45 minutes before continuing. Not really feasible if your using your laser commercially.

[@SarbarMultimedia]

Thanks for an excellent point. Because I never use my shop compressor it has never been a problem . However, as I demonstrated, this compressor is exactly the type most people buy to upgrade, and if you try to run it at 30psi , it does run continuosly. I hope others read this important limitation.

[@gdro]

Maybe I got this wrong but should I understand that for max efficiency and better health of the machine you should run the job in different batches ( engrave / cut). You cut closer to the surface (first job) and engrave a bit further away (second job). Maybe it’s a silly question, I’m new to this craft 😊.

[@SarbarMultimedia]

`Hi George. That is a sensible conclusion that you have reached and crtainly for a new user I would suggest optimising each process.. It depends on what you are trying to achieve as to the best method to use. a) If you are doing a repeated shape (maybe coasters or keyrings etc) where the engraving may or may not be the same on each one but you have say 20 or more to do, I would suggest the template method. Draw both your cut and engraving on different layers but first disable the engrave layer. Cut all your blank shapes out with a cutting setting ( it depends on your lens tube and nozzle as to whether you can do this wirh a small gap). Once you have a pile of blanks, tape a piece of scrap material securely to your machine bed. Set an origin point and cut the shape one more time. Remove the scrap shape and do NOT touch the origin button again. Now enable the engraving layer and find the ideal engraving settings. You can now put your good blanks into the template shape to get perfect registration for your engraving/s b) Find a compromise solution that breaks all the basic rules. In this video you will see me using an "engraving " setting to also achieve cutting. I have the luxury of a large choice of lenses and nozzles , along with a lot of experience , that allows me to make choices that others may not even consider. This video was done for a friend to help make a fairly simple product into an efficient manifacturing method without the need for templates. kzbin.info/www/bejne/fqi5qJKKr956qK8. Once you understand the basic methods for using this technology, there are unlimited ways to use your curiosity and imagination to find YOUR method. Remember that failure is just a stepping stone to success BUT you must be very self critical and recognize what failure looks like..Would you buy your product for moeny?....that's always a good way to judge success. All best wishes and good luck in your new journey.....Russ

[@gdro]

@@SarbarMultimedia Russ thanks for taking time to reply and explain.

[@avelkm]

I want to correct you on something. There is a usecase in the middle between cutting and engraving. It is a deep engraving. I use it for two purposes - engraving for inlays (epoxy, crushed stones, glow in the dark powders or "marketry"-style) and for contrast engraving on dark or porous wood(Bog Oak is both:). For that application you definitely need an air assist with decent (pretty high) flow mainly to cool the material. Also I use 1000 DPI to have smooth bottom, on 300 ("ideal") or even 500 DPI there are visible lines (that's true not only for deep engraving but for any logo).

[@SarbarMultimedia]

Hi I must first thank you for pointing out that there are exceptions to the general rules and for your application, I respect the information you proffer.. The fact that you use the term DPI indicates that you are using an RF laser rather than a constant current glass tube system. I have both technologies and have experienced of the performance differences. This video was focused on the confusion many people have about the physics of air pressure and flow and not really about the effect of air assist on the material itself. In principle for both technologies you only need air assist for cutting, not engraving. The way in which an RF beam can be focused with a lens is significantly different to that of a glass tube beam. The higher central intensity of a glass tube beam is significantly better at vapourising wood without charring or burning but it still produces resinous tar vapour. Blowing that back into the work is actually adding a more flammable material to your engraved surface.A long focus meniscus lens (maybe 2.5"/63.5mm), a big air gap along with significant cross flow fume extraction may help with your burning problem without the need for significan air assist. I must hastily add that although I have worked with many types of hardwood,including ebony, I have never worked with bog oak, so there may be some peculiar material properties that I cannot account for . If you have not seen it already you may wish to watch my explantion of how and why air assist works the way it does with materials as this is more applicable to your engraving issue. kzbin.info/www/bejne/bWq5i52Dmct1o6s The fact that wood can be vaporised to maybe 0.75mm deep without burning is demonstrated in this video at 22:30 onwards kzbin.info/www/bejne/hJKYkGmloLqsgck Part of my learning experience is by gaining information from others. Please take a look at the two videos above and do some experiments with your bog oak. I would be sreriously interested in any feedback that you can provide. Thanks again....Russ

[@avelkm]

Ross, I confused you by mentioning dpi) I use K40 with stock software, so I'm referring to dpi in the corel plugin (yeah, I'm planning to change a board and software to lightbirn) I've watched a ton of your videos throughout the years, almost from the beginning and did dome experiments. First of all, specifically for Bog Oak I have problems with thin details on deep engraving without air, especially when they are islands. Second, I don't use air assist nozzle as in a video, I have a thin tube roughly at 45° angle pretty far from workpiece. It still leaves residue on oily wood or resin, so you have a point here. On Bog oak there's no residue as it's very "dry". My small aquarium pump recently failed (membranes torn apart) and I used my big 2kW compressor and was not happy))) This video is really helpful for choosing my next pump, thanks) have a good day!

[@avelkm]

btw, what board should I buy know, I want three axis (rotary as third) and ideały work without usb connection for batch work? Coehision3d looks like the thing I want but they are out of GLCD (needed for work without pc) and no support on forums for last year or two. Are there any alternatives except Ruida (too expensive for k40)?

[@SarbarMultimedia]

@@avelkm Yes, even the cheapest 2 axis Ruida RDC 5121 is $279. But in reality you only need two axes because Y is dead whenever you use a rotary. The K40 Xtreeem that I created used a 2 axis controller and when I ran with the rotary I just switched the driveer to the rotary and loaded another vendor setting file that had the different calibration data in it. It worked perfectly. I don't know which country you are in but it may be a more worthwhile option to look for a preowned 5030 machine that has everything you need . The great advantage you have is experience and machine knowledge. Many quite decent machines appear on the market because the technology is not the dream that the original buyer thought. The learning curve was too steep. Your K40 also has value on the preowned market because laser diodes (the modern K40?) are VERY expensive. Thoghts on the wood I want to buy? Russ

[@avelkm]

@@SarbarMultimedia My k40 is having 10-year anniversary this year. For years now I'm tempting to throw it away and buy something better more precise. But I live in Ukraine... Unfortunately, the cheapest 3050 is $4000. Also, I really need a smaller more precise machine and not bigger one, but I'm stuck to CO2 because of the materials used, neither expensive RF nor cheap diod lasers work well both on wood and clear epoxy resin with added mica powders. Just today found a hybrid laser with CO2 tube but the galvanic head, no price though, waiting a call from a manager, but it wouldn't be cheaper than $3000-4000 without a rotary. And this price is hard to justify, I charge $50 per custom engraving and sell may be 50 a year at best. On corporate orders for 20-50 pieces, it's at most $10 per engraving, a few times a year. Can't outsource either because of high accuracy requirements and jewelry engravers can't do wood and epoxy. Thanks to your suggestion I have at least found a very nice new k40 version with much nicer mechanics and better optics for around $600, it has a lot of upgrades except it still uses M2 nano, but at least it's worth upgrading (mine is very worn out but still stays aligned pretty well). Then I could probably sell mine for $300 or better yet leave it for spares or as an emergency swap (it has new-ish Cloudray tube, lenses and still working power supply:)). As for 3rd axis, I'm doing this for years, swapping rotary with Y axis but it has it's problems - I have to manually position Y axis, it can shift suddenly and worth of all when I forgot to tick "rotary" in laserdrw and design gets stretched ruining hours or even days of work. As for wood, you wanna buy bog oak for tests? Bog oak is VERY expensive (mine is carbon dated 3000 yrs old). I could've send you some offcuts that I use for tests, I don't know how long will it take to reach you. Are you in UK? Can't decide from the accent:) I think standard white oak have some similarities being very porous, though it is not nearly as flammable. As a test design you can use the Ukrainian coat of arms, it has this four small features in lower part that are somewhat challenging. Can I contact you by email, I could send you pictures and designs I'm talking about and may we can workout sending you samples of materials. I still don't know which lenses should I really chose for my usecase, stuck on 2" from Cloudray:(

[@krisknowlton5935]

After watching most of your videos I finally purchased a Cloudray CR7050 55 watt laser which I received last month. Then, earlier this week Cloudray said I had won a Russ designed Super Ultimate Air Assist system to put on my laser. I've read all the comments on this video and it seems that one person does not have nice things to say about Cloudray. Do you find their lenses to be of poor quality? From my experience with Cloudray is they have high quality machines. I have been using my 50 watt fiber laser for over a year with absolutely no problems.

[@SarbarMultimedia]

Hi Kris You can never assess why some one was unhappy. I have done a huge amount of experimentation with lenses over the years and have several lenses in my "dead" box but I blame every one to my own experimental stupidity. I have experimented with expensive ll-Vl lenses as well as standard USA CVD material, normal brownish Chinese PVD lenses and Gallium arsenide material. Lens manufactiureres use the same sort of grinding and polishing machines to achieve the spherial geometry common to almost all lenses , certainly those used in our machines. The major differences in lens quality is the material itself not the optical geometry. That geometry (by the laws of physics ) must be the same for all manufactures. Any minute geomtric differences between Chinese and USA lenses would be significant were they to be used on the James Webb telescope, but we are not focusing IMAGES of uniform light, instead were are focusing the varing Gaussian INTENSITY of a laser beam over just a few inches. Simply put, you can pay a fortune for a lens and see no performance gain.. Different materials have different power limitations and you must be aware when buying a lens. Chinese PVD lenses are fine up to 80 watts. Above that, you must use USA CVD material which will be good up to at least 200 watts . Gallium arsenide is rated well above 200 watts but becuse it has a different refractive index, the GaAs lens will have a flatter geomerty (larger spherical radius) when compared to a ZnSe lens. There are certain beam intensity profiles that suit the flatter geometry. Your own experience is more valuable than others opinion. Best wishes.....Russ

[@VladOnEarth]

To add something to your video Russ, I would like to tell that you are mostly talking about cutting wood here I assume. For exampl3 with my EVA cutting setup, I absolutely need airflow AND pressure too, otherwise, because foam burns so fast, I get burned off edges when I engrave or cut. For rubber I fiund it very beneficial to have a higher pressure, because those carbon burned particles stick to rubber and stay there, causing all kind of issues. My experience with big compresson was a total disaster, very inefficient and generates a LOT of moisture, so I jist upgraded my system with a similar pump that it cane with, just 4x larger and with more flow, super silent too, and I am very happy with it actually. Where a lot fo flow is very beneficial imo also is the exhaust system, i now upgraded from 36W fan there to 180W and it made a huge difference. Almost never need to clean lenses now, especially with that custom window I made. My next upgrade would probably be at thia point to build my own machine from the scratch, just to get the gantry and other things precise and correct. And put servo motors into the system, the existing machine is as upgraded now as it can possibly be, thank to you too, and your advices! I have researched faster HV PSUs and no luck there at all, everyone just producing the same design from last century, nobody wants to innovate there unfortunately, including Cloudray company who are just chinese resellers basically of other companies stuff, and they arent great either, I bought their lens on amazon and the lens failed after 1 hour on my machine, they also use cheaper grade material for their lenses and never disclose that. They send freebies to youtubers for their own benefit, I get it, but I would personally never support them.

[@SarbarMultimedia]

Hi Vlad I agree that there are special cases to be made for difficult materials like your rubber. The carbon content is a bit of a killer. Higher flow rates are not really removing fumes in your case, instead its blowing away solid carbon particles. Very few people are dong what you are doing so this video was aimed at the masses who are cutting wood based products and acrylic and think that upgrading to a shop compressor is advantageous. Building your own machine is a great idea now that you have the experience of what does and doesn't work for your situation. Always good to hear your comments Best wishes Russ

[@VladOnEarth]

@SarbarMultimedia it's too boring to do what everybody else is already doing 😛 and it doesn't pay well either. Plus I loved the learning curve of all this and an achievement now to be able to nearly perfect the process, not without your help! Thanks for that!

[@SarbarMultimedia]

@@VladOnEarth Your kind words are appreciated but remember that everything we discuss and you suceded with is great learning for me also. I learn a lot from helping others because there are many issues that I never encounter personally. Thanks.

[@VladOnEarth]

@SarbarMultimedia we both learned new things, what can be better! Haha. 🤖🤖🤖

[@petervaiciukas8727]

Hi Russ Long time since I messaged you and I hope you are well, I have lost your email address. It is reassuring to see your video because your conclusions match with mine that its more about managing airflow than air pressure. My cuts are perfectly clean both sides. There is another bit of the video that sparked an interest for me that I haven't yet explored for having crossflow air blowing horizontally over the workpiece. I have the Cloudray air assist system installed so when I engrave I can lower the air flow with a regulator but even with this, when I engrave I suffer with the contamination still being blown into the work piece even if the positive air flow through the nozzle is down to 0.5 litre per minute. I noticed the improvement in your engraving when you had cross flow air so I have temporarily fitted a 2nd air line to blow like a blade horizontally over the tip of the nozzle. This has improved but there is still notable contamination which actually falls towards the door opening so against the fume extraction air flow. Can I ask what camera you used for the slow motion video? I would like to do similar on my machine to see if this gives any insight into how the fumes are still being pushed down and also towards the enclosure opening. You are welcome to email me if you still have my email address. Very best wishes. Peter

[@samlenlap]

*addon Guys i am trying new idea I am going to try Ring Blower or Side Channel Blower which is used for bio floc fishing water airator If anyone know anything about it please reply

[@InlayMasterdeveloper]

Your statements are more than wrong. of course your manometer does not show pressure. Because the air passes by... The pressure is looking for the easiest way. If you had made cutting charts with compressor or air pump in practice, you would be more credible.

[@InlayMasterdeveloper]

I had supplied an ACO 318, but could only cut at 12-14mm/s. With compressor @30psi /45L sec suction power ) I get 30-50 mm/s with 4mm poplar. Practical values would be better than your theory explanation

[@SarbarMultimedia]

@@InlayMasterdeveloper I greatly appreciate your comments and interesting data. Was your cutting improved to 30 or 50mm/s? This video was never about the EFFECT of air assist (that is dealt with in another video) but the misunderstanding that many people have , believing that 30psi at the regulator gives 30psi at the nozzle.

[@InlayMasterdeveloper]

@@SarbarMultimedia i can cut 30 to 50 mm/sec (4mm Ply Wood)poplar very easily with 30 psi and the compressor (16mA ). Your video is understood in Germany so that a simple air pump is sufficient, which I can not confirm