RDWorks Learning Lab 188 The 4 inch Lens Part 1

[@andyspoo2]

Does it make for a thinner cut all the way down the depth of the acrylic? With a 1.5" lens I find that the slower I have to go for the thicker the acrylic, the edge of the cut is angled, i.e. wider at the top and thinner at the bottom. I'm guessing the 4" lens would also work better for wood that's also slightly warped, where the distance from nozzle to the wood will vary (I find that some sheets of wood are perfectly flat where it's mostly intact, but will warp when some items have been cut out of it, and therefore it's rigidity has changed. With your lens setup here , the nozzle is further away from the material than before, because of the focus point. Will that also effect the air hitting the material, and change the cutting performance at all? If the lens was further up the lens tube, would that have helped with the cut at all?

[@andyspoo2]

I just noted that you've answered some of this in your reply to John Hunt, below, which I did not see because the reply was not expanded out.

[@SarbarMultimedia]

Hi Andy A 1.5" lens will focus to a pretty small spot size with very little halo. That means that if you set the focus exactly on the surface there will be no peripheral halo power to burn the top of the cut wider. It may take a little longer to cut through but with the right speed you will produce a virtually parallel cut. If you try to run too fast then the bottom of the cut will be "though" but not properly through and you will finish up with a very narrow breakthrough at the bottom that will not let the fumes out properly and also will be a tapered cut. Acrylic cuts very slowly (in fact it evaporates) and you cannot hurry acrylic no matter how much power you chuck at it. A commercial business near me runs 10mm acrylic at 12mm/s with a 200 watt laser. Many things about the 4" and long focus compound system are yet to be discovered Sorry, I cannot answer some of your questions. I hate guessing. I like to deal in proven facts. Best wishes Russ

[@andyspoo2]

@@SarbarMultimedia Cheers for the reply Russ, and thanks for the tip.

[@rogini_music]

Really good work! You are doing valuable content! 👌🏻 Greetings from Poland 🙏🏻

[@naeemmawji]

I love how you programmed it to drop 1mm after every pass in order to investigate the best cutting distance from the lens. How did you create a file that does that. Do you have a video in which you explain how we can write the code that would allow us to do that? I am familiar with writing my own G-code for my CNC, I am hoping there is a way to do the same for the Ruida controller.

[@SarbarMultimedia]

Hi Naeem First take a look at this kzbin.info/www/bejne/f3XEeHirZcmXqKc and then this kzbin.info/www/bejne/r4CVhXeVnZ2SpKs Hope this explains all Best wishes Russ

[@dinesharts7777]

Sir your videos are very helpful...! Great work sir...!

[@dietmuse]

I would like to cut through 10 mm thick very hard hardwoods. Would a stock Chinese laser cutter like yours do this, or would I need a 4 inch lens for that? I don’t care if the cut is a little charred because I can just sand it down.

[@dietmuse]

(By “stock” I mean one without all the tweaks and mods you’ve made)

[@SarbarMultimedia]

Hi Stephen From the various clues in your question I would position you somewhere on the East cost of USA. I would say that there are several importers of Chinese machines in your huge country but most are adding just a little value in that they are maybe doing final setting and debugging and in return your are paying a huge margin to support their infrastructure. In all honesty I can only recommend one known good quality Chinese machine that is available in USA and that is ThunderLaser. (I think they are in Texas) I have been critical of some of their over-enthusiastic claims but I have always respected their engineering quality and enthusiastic customer support and one big plus in my books is that they are up front with their pricing www.thunderlaserusa.com/pricing/ So now it's a matter of what size machine do you need (not what power) to do your job. The one problem with many machines, including TL is that size, tube power and price are solidly interlocked. This is a totally unnecessary linkage and is actually more to do with packaging convenience. A big tube in a small machine is a major crating inconvenience. For instance the 600x400 TL machine seems excellent value at $4500 but it only has a 40 watt tube and that will not do your 3/8" hardwood job. You need to be throwing 100 watts at it To do that you need to pay another $5200 for a stock machine that is more than twice the size whereas for about $500 you can upgrade the 600x400 machine to suit your needs. Finally, I hate to be a party pooper but as far as the laser is concerned there is no such thing as hard wood, They are all organic materials and the way the light interacts with the cellular structure to heat it is extremely complex and varied. The generic term hardwood implies there is a denser grain structure with more resinous content. That does not necessarily mean it is difficult to cut. As a woodworker you will be aware of the fume dangers , but many will think that wood smoke smells great and is harmless. Hmmmmm. If you have a company selling lasers in your area, why not arrange a demo session with them "as a potential customer" and take some wood samples along to determine what power of laser you need (i'm sure 100 watts will be fine) and then decide on your purchasing strategy . Best wishes Russ

[@dietmuse]

SarbarMultimedia thank you so much

[@mauriceshay4958]

Hello sir I enjoy your vids a great deal and have learned so much about engraving and my Machine which is a 30watt. I would like to know how can I recieve you're information package as well as the Acrylic gauge to measure laser head distance. thank you.

[@SarbarMultimedia]

Hi Maurice Just add your disguised email address (johndotsmithatgmaildotcom) to another comment and I will contact you and also delete your comment/email address. Best wishes Russ

[@johnhunt2390]

Please investigate air pressure as a variable in cutting wood. (Supplied to the nozzle.)

[@SarbarMultimedia]

Hi John It's not necessarily air pressure that natters but air flow. When you fire our beam of invisible light at wood there is a SURFACE conversion of energy into heat. In the same way that a sone falling from the sky does no damage until it hits you on the head , only when something gets in the way of the stone will it give up its kinetic energy into a different form, That is exactly how the laser beam acts. Put something in its way and it will hit the SURFACE and excite the atoms and molecules to vibrate faster and THEY will get hotter (rapidly) When they reach a critical temperature there will be a critical chemical reaction where the cellulose will break down and combine with oxygen and other atmospheric gasses to (very crudely) create smoke . In the same way that steam is not a gas, it is micro particles of water suspended in a gas, so wood smoke is the same. Two major things happen. A) smoke is thousands of times more volumetric than the solid wood that it was, so it is going to expand rapidly. B) The smoke is still micro solid suspended in air so those particles are going to absorb the light energy from the beam, will heat up even more and ignite becase smoke is flammable.. That is in effect reducing your beam's ability to cut if it has to fight its way though a smoke cloud to reach the work surface. Thus it is obvious that we need to keep the smoke away from the beam., hence we use air assist to blow the smoke out of the BOTTOM of the cut. If the smoke come upwards it will get blown down onto your work and condense as a brown mark around your cut. To achieve this goal you need an EFFICIENT flow of air through your kerf (cut) The kerf is narrow so you cannot get huge amounts of air through it, hence my emphaisis on the word efficient. Several factors affect that efficiency. 1) The size of the orifice in your nozzle. A cutting nozzle should be between 2mm and 2.5mm diameter 2) The distance of the nozzle from the work, 3mm is ideal but up to 5mm is OK 3) FLOW of air through the nozzle. Air flow is related to pressure so theoretically the greater the pressure inside the nozzle the faster the air will flow though the orifice.. The problem now becomes a physics issue. Air is compressible so to make it flow through that orifice it has to be compressed. that means that when it exits the nozzle it will expand. An expanding jet of air is not going to be very efficient at getting into the narrow kerf. if most of it has spread out. So just 2 or 3psi will be sufficient to force an adequate amount of air through the nozzle 4) Speed of cutting. If you watch my MDF cutting again you will note copious amounts of smoke welling up out of the top of the cut. That is because the CUT was too fast and not efficient, Although the cut was right through and I was able to remove the square (that was all I was aiming to do) the cut was wide at the top and almost nothing at the bottom. That narrow (just through) cut was choking the flow of air from exiting freely out of the BOTTOM of the cut. hence the brown mess on the surface. In reality I probably should have run at about 8mm/s for an overall EFFICIENT cut. I hope you can now understand that there is quite alot of science to comprehend. It's not complex stuff but with no understanding of the detail you will never be able to decode your cutting issues Best wishes Russ

[@atmospheredecor5228]

I find 2 to 2.5bar is best for 6mm mdf

[@SarbarMultimedia]

@@atmospheredecor5228 High pressure usually means more air flow but it depends where you are measuring the pressure and what are the restrictions on the way to your nozzle . The key thing about air assist is EFFICIENT FLOW THOUGH THE KERF. It maybe that your system is flow is limited by a very small bore through the fitting to your nozzle. If (for example) hat orifice is blocked off there will be zero flow but your pressure gauge will still read 1 bar. My point is that pressure is no reliable indicator of flow. It is the air flow through the nozzle orifice that is key to efficiency. If your orifice is large (maybe 4 or 5mm) and the gap to your work is large (say 6mm or more) then the chances are that the fitting that feeds air into your nozzle is the limiting orifice (maybe 3mm). That is less than half the area of your nozzle and the air will be turbulent as it expands and find its way to the work surface. More pressure will mean more turbulence and less efficiency. Do you experience brown edges around the top of your cut?. Low pressure, a small nozzle orifice (typically 2mm) and a small gap to your work (about 3mm is ideal) is the EFFICIENT way to force air through the kerf. Any air that expands ACROSS the surface risks dragging the fumes onto the TOP surface of your work. I learnt this lesson very soon after I acquired my machine. Coming from a metal cutting laser background, I laughed out load at the stupid little pulsing air assist compressor. I hooked up to my shop compressor with regulator and filters (just as I had been used to with big machines). I will not go into the story other than to say that after 3 weeks I swapped back to that stupid pump and although it delivers max 0.3bar , it has worked perfectly for almost 5 years now. Airflow through my nozzle is about 8 litres per minute. Best wishes Russ ps I am super envious of your artistic skills!!!!

[@lowsideswitch]

where can I get a copy of that spreadsheet?

[@SarbarMultimedia]

Hi Abby I have done a much more comprehensive set of lens tests that may be more interesting to you. I can send it to younif you like to add your disguised email to another comment. KZbin has algorithms that prevent email address transfer so we now have to be smarter tha Google. Here is an example of what works. Use sentances ....... If you start with john and a dot follwed by smith thats a good start. An at symbol and then g++m__ai??l etc. That has not failed yet. I will then delete your comment Best wishes Russ

[@lowsideswitch]

Ive thoroughly enjoy the content you provide. Your demographic is such a small market I know its hard to get subscribers but your content is top notch. Thank you for the hard work.

[@SarbarMultimedia]

@@lowsideswitch Hi Abby To be honest I am not in the least bit concerned about subscriber numbers because this is a very selfish learning journey that I am on with this tchnology. I do not monatize , I am happy to freely share my experiences. Ther are no plans for my journey. if I observe something that does not make sense, my natural curiosity drags me off to explore and hopefully understand/decode. It took 3 years to decode the mechanism by which lenses cut and now, understanding that opened up a whole new world of to explore about lenses and laser beams. When you get to my age you need something stimulating to keep the few few remaining grey cells exercised. I never want people to believe I am teaching, that implies I am an expert, no, I am still a student but maybe a bit further up the learning curve than many others. Best wishes Russ

[@lowsideswitch]

@@SarbarMultimedia well thank you again. keep up the good work. The laser I am watching videos for is a 150w Co2 with a 4'x8' bed...I also have a 1000w fiber laser as well as a 100w Co2 Galvo laser.... have you played with either one of those? Did my email message make it across?

[@SarbarMultimedia]

@@lowsideswitch Hi Abby No email from your or any comment with a disguised email address yet, I understand fibre laser technology because a lot of my learning with the CO2 glass tube lasers has been transferrable. I did have a 20 watt JPT MOPA galvo head laser that was loaned to me by a local company. It was on loan for me to dig into the darker corners of the technology to discover things beyond the normal applications that the company was selling to their customers.. At 20 watts this was only a marking machine. The company builds bespoke marking machine applying all types of laser tecnology to mach client requirements As yet no metal cutting machines. So your 1000 watt device is a REAL cutting machine. Do you run inert gas for cutting? I have a friend with a 60 watt CO2 galvo but in reality it is like the fiber laser but using a different wavelength of light. It is still a marking machine for organic and mineral materials. I have built a budget RF CO2 machine based on a 30 watt unit and after all the hype from the big sellers, I was expecting to find some real magic in that technology. Hmmm , it turns out to be smoke and mirrors and a very complex and non exciting technology. It insulate users from the technology with an array of menus system software. After being switched off for almost a year, my new found knowlwedge has tempted me to fire it up because I can see a fantastic opportuniyt to transform its performance. Your venture int a large bed CO2 machine is a minefield. We must link up because there is so much that could go wrong with that prurchase. NONE of your current experienc will have prepared you for this much simpler technology. Best wishes Russ

[@MilanKarakas]

OMG, 4 inch lens... that will not fit my K40 laser cutter. Or, I should to remove bottom metal in order to put workpiece there. :D

[@SarbarMultimedia]

Hi Milan Remember that this is effectively beam convergence NOT the BEAM EXPANSION you were advocating for the RF beam. Perhaps you can now see why I am ignoring all good optical practices. If I'm told I should do it, I want to understand why . So here is another mental conundrum for you. BIg smiles Russ

[@MilanKarakas]

@@SarbarMultimedia True. Maybe one day I will try to buy variety of lenses, from shortest possible focal length to the longer one. Just space beneath laser head is small, so long focal length is out of question. And, yes - mental exercise is always welcome to keep all remained grey cells active. :)

[@nigelconroy3944]

Great content as always. I have one question around the cost of these lens, a quick search on cloudray shows only very expensive lens in that focal length, are these 7.5in lens going to be really expensive?(you usually are concious of this) Obviously you aren't are the stage that you are recommending a 7.5in lens yet but it's an early indication that these may be useful.

[@SarbarMultimedia]

Hi Nigel I hope I make it clear that I have gentleman's arrangement with Cloudray whereby I give him designs to manufacture for the community at Chinese prices ( and it absolves me of any long term manufacturing responsibility) and in return he sends me the necessary items that I need for experimentation.......totally non-commercial and it work to all our benefits. Thus at this stage I have no idea of the lens cost as I am more interested in the outcome BUT I am mindful of the potential gains for some users. My very quick and dirty tests were just to see if there is any promise in the direction I am heading. I may have hit a "sweet spot" by pure accident but I suspect there is a LOT more to learn. IF there are gains to be had in depth of cut or cutting speed, it all then becomes a value judgment according to your individual needs. Normally to cut deeper or faster you would have to upgrade your tube and power supply and that is a VERY expensive decision, so this may offer a much more cost effective way to gain cutting performance. Best wishes Russ

[@nigelconroy3944]

@@SarbarMultimedia Thanks Russ, it most certainly is clear about your arrangements and I for one have benefited immensely from it. I know that cost is always something you keep in mind so was just asking out of curiosity more than anything. It would be annoying at the end of all your experiments to have hit the sweet spot on an educated guess at the start but I wouldn't be surprised!!! Agreed a lens upgrade could definitely be cheaper then a tube and power supply upgrade. I look forward to the results. Thanks

[@Kubachini]

Спасибо за Ваши видео! Thanks for video!!!

[@dinesharts7777]

Sir I m facing a problem installation of rdworks, the installation gets complete At last it shows. install failure error Anyone knows the solution for this I tried installation on 3 different PC's with 3 different windows operating systems winxp, win7, win8 but the same error occurs.... Pls help Iam unable to operate my laser since 8 days...

[@SarbarMultimedia]

Hi Dinesh There are many versions of RDWorks. Ruida continually upgrades and adds features. However Chinese software quality control management is pretty poor and often something that works perfectly in one version is completely broken in the next revision. I think the current issue is at 42 or maybe even 44. I have been using issue 38 for some time now because it is stable and relatively bug free. I have it installedon win 7 and win 10 machines. You can download a copy from my drop box link. www.dropbox.com/s/8xugiag5alqlp4v/RDWorks%20ruida%20issue%2038.rar?dl=0 Best wishes Russ

[@dinesharts7777]

Rd works v8.18 Rd works v8.41 Both versions tried but same error