RDWorks Learning Lab 103 Gold Mirrors

[@gaolave]

Hi Russ, thanks for sharing this experience. Every day I'm waiting for a new episody... Guido from Santiago, Chile

[@jameslamb4573]

Thanks Russ. I had it in mind to get a local Silversmith to knock me up some silver mirrors, doesn't seem to be any point to that experiment now.

[@SarbarMultimedia]

+Hi James Rob and I did discuss plating a set with silver but we decided against it because of it's tendancy to oxidize and tarnish so easily. Gold is obviously impervious to oxidation and promised great potential. Many thought that copper would tarnish quickly but in practice 6 months or more between light polishes seems normal.. I am staying true to my copper mirrors because because I already have them, but still have my moly set as backup (and 2 gold sets!!) Glad it saved you the expense Best regards Russ

[@DoRC]

I wonder if the gold coated ones were mirror polished if they would work better?

[@SarbarMultimedia]

These mirrors were lapped dead flat and had a good reflective finish before plating. After plating they looked exactly the same level of shininess as the Chinese mirrors. It is possible that a light polish may improve them but to be honest I've spent far too much time chasing those last 1 or 2% efficiency. It's been informative for me and others but I have concluded that there is a practical barrier at about 97% and after that the cost of achievement is not worth the effort. Accept the fact of a 10% loss through the system and if you need a specific work-face power then choose a bigger tube at upgrade time. Best regards Russ

[@Viragoman11]

Love your vlogs.

[@ottosouta7445]

Hi Russ, this is fantastic trial, it answered my question perfectly JIT. I was going to do the same, but as you ventured on the journey, I just stood on the roadside and I am happy to read you findings. As you say, chasing the last 1-2% is rather costly, I had a quote from optical manufacturer of several hundreds dollars for ONE mirror with 99.9% reflectivity. They may have some dichroic coating, but what the heck. So I will happily use my molybdenum mirrors, costing fiver each. There are horses for courses. Thank you very much for doing this, and sharing it with us. Now I have task in front of me - mechanically modifying, adjusting and setting true the Dragon's table, X & Y carriages, Lens tube and squaring and opening the 45 deg. mirror holes. regards otto

[@SarbarMultimedia]

Hi Otto I'm glad you did not spend your money also. It's cost me quite a bit when I think of 3 Chinese crap mirrors, professional lapping of 12 copper mirrors. the laser cutting of those discs plus carriage charges, but it became a bit of an obsession to find a definitive answer and I'm glad the journey is finally over and we have answers rather than opinions. if you look at several comments below you will find people asking if it would have been better to polish the gold mirrors. Maybe but for 1 or 2% do I now care? Thanks for your input along the way Best regards Russ

[@ottosouta7445]

If I was you after all the huffing and puffing and credit card flexing, I would pour myself a glass of wine and put my feet up. You at least have 70W tube, mine is 50W at the beginning of it's life, so I will have to use it before it dies, as they do not keep as spares apparently. Is it true, that the actual claimed 2000 to 4000 hours life is not the actual working ON life, but just time form the initial manufacture of the tube? regards otto

[@SarbarMultimedia]

Hi Otto Thinklaser, who have direct contact with the manufacturing plant in China have established that the claimed life of a tube is it's "shelf life". It is all to do with the epoxy used to bond the mirrors to the tube. The gases in the tube are under partial vacuum so there is a gradual ingress of external contamination. Even Reci ,who are about the best tube maker, are a bit cute with their tube specs and warranty period.They advertise 10,000 hours tube life (shelf life is therefore 13.7 months) but the warranty is only 10 months, with further running current restrictions to qualify for that warranty. Thinklaser are sufficiently honest about this fact that they give you a replacement tube at the end of the 1 year warranty period. My 70 watt tube was only ever claimed to be a 4000hour tube (= 5.4months) and is now at 14 months and still going strong (maybe 2 or 3 watts down). I would take this fact as a warning to hold off buying a new tube until you need it. With a through flow of machines, I know that Thinklaser will be stocking 40 and 60 watt tubes for resale, because they can keep their stocks fresh. Regards Russ

[@ottosouta7445]

Hi Russ, thanks, yes, it is the term "shelf life" I was looking for. So what is the actual useful working time one can expect out of the "fresh" tube? There are the catalyst and non-catalyst tubes helping to keep the gas mixture in balance. We have been warned not to actually run at 100% current, as that shortens the life, and my own measurement told me that going over 65-70% does not significantly increase output power. So - how long is the piece of string, or is there MTBF? Perhaps the power gradually drops, until it does not cut any more. I also read somewhere that the pink colour of the beam is sign of a healthy tube, white is not so healthy. Not that I have in mind to run mine 24/7. regards otto

[@SarbarMultimedia]

Hi Otto Yes, you are asking me "how long is a piece of string?" I am expecting 2 years and many folks with known good tubes are at three years and beyond. If you are unlucky enough to have a KH Laser "brand" that period could be days to months with a high degree of certainty. There is 10% nitrogen in the tube and that is an essential "driving" ingredient. It is the ionization of this nitrogen that you see as the pink glow. Gasses do not normally conduct electricity but, when ionized, the nitrogen can do just that. As it carries current its energy (and temperature) rises. You then need 80% helium to act as a heat conductor to transfer heat to the water jacket. Below a critical current flow, when the nitrogen collides with the CO2 molecule it can impart some extra energy to it. Unhappy to be carrying this extra energy, the CO2 molecule gets rid of it in the form of a photon of invisible IR light. It is this light that is then mechanically amplified by internal mirrors before exiting the tube as usable energy. However, if you program more than the allowable critical current (%power) then the energy level (and temperature) of the nitrogen gets so high that the collisions with CO2 split the CO2 into CO and a free O. You are now destroying the one thing that makes your tube work, the 10% of CO2. Remove the excess current and there is a percentage recombination that takes place because of some trace hydrogen catalyst that is also added to the gas mix. This is not that efficient and not the catalyst mentioned for long life tubes. Even under normal operating currents, there is an occasional "dissociation" occurring. To mitigate this normal loss of CO2 they do two things. 1) they make the tube fatter so that it can hold more gas mix. 2) if you look closely at the inner central tube you will see it has a faint pink tint. That is because it has a vacuum deposited film of gold on the inside of the tube. Gold is a more efficient recombination catalyst and is the trick they use to give long service life. If you do have an ammeter fitted to your 50 watt machine, then, if it is a true 50 watt tube (1000mm long), you should never exceed 20mA. If your tube is actually a 40watt tube (800mm long) then do not exceed 19mA. If you do not have an ammeter then stay safe and never exceed 65%power setting. Hope this VERY brief explanation answers your questions. Regards Russ

[@cmachielsen]

Russ, can you tell me what to buy for mirrors for my lasercutter?

[@SarbarMultimedia]

Hi Christ The only mirrors I would recommend are solid molybdenum No matter how expensive and whatever the claims, do not ever buy plated mirrors. You can clean these moly mirrors acetone if you really need to but generally iospropyl alcohol will suffice. Plated mirrors wear through after a few cleans Try these www.cloudraylaser.com/collections/co2-mirrors/products/cloudray-high-quality-mo-mirror-dia-15-19-05-20-25-30-38-1mm-thk-3mm-1pcs-custom-made-for-co2-laser-engraving-cutting-machine?variant=7645314744371 Normally they will be 25mm diameter but check diameter before you buy. At about $5 each these are fabulous value Best wishes Russ

[@cmachielsen]

Russ, thank you! Currently working on my chinese laser. Bought this without the Ruida controller and laser tube. Fitted a 80watt laser tube from Reci inside and need to change the mirrors to get a good quality of products. I changed all wires inside the control cabinet. Lot of work but hopefully it will be a better machine.

[@SarbarMultimedia]

Some older machines have 20mm mirrors. If you are upgrading you may want to also consider new 25mm mirror holders for at least positions 1 and 2. Sadly it will mean a new head as well if that is 20mm. The whole kit is not that expensive. Best wishes Russ

[@Viragoman11]

Hi Russ. Tell me can you up grade a Laser Machine to be able to cut metals as an example? I bought a machine on the understanding that it could cut metals. Thanks Russ. Rob.

[@SarbarMultimedia]

Hi Rob Maybe. You require several things for a metal cutting machine. First a lot of power, at least 130watts. Secondly you will need a special head that has an pneumatic or stepper driven lift/autofocus. It's a lot bigger than the normal head. You will need a cylinder of oxygen for mild steel and masses of nitrogen at high pressure (150psi to cut stainless steel to use as the cutting assist gas. I owned two 3kw metal cutting lasers as a profiling business for 10 years and when they sell or demo these Chinese machines they never mention all the infra structure you will need. see kzbin.info/www/bejne/aZandXRmdtiEjNU Listen to the high pressure gas leaking away $$$$. There is just a flash of the gas bottle. I think they are using argon rather than nitrogen as a cover gas in this case. The cut edge looks a bit black. Sorry for the disappointment Best regards Russ

[@Viragoman11]

Thanks Russ.

[@RabHaw1947]

Hi Russ, I was just wondering if you have tried the mirrors made from hard drive platters and if so how did they compare?. cheers. Rab

[@SarbarMultimedia]

Hi Rab I had heard the myths and as usual I have been there and tried it for myself, kzbin.info/www/bejne/fnnEmKykgZmtp9U Best regards Russ

[@RabHaw1947]

Hi Russ, just watched that video, I must have missed it first time around ,very informative, I won't be trying to make mirrors out of hard disk platters now. cheers.Rab

[@natedavies9718]

Hello Russ, thank you for your videos. so helpful! You are a wonderful teacher. I run two 60 watt Ebay Chinese lasers. The black and red runs that I think are the next step up from the blue and white one that you have. I love them!!!! As I think you have mentioned, I don't even bother with the tubes they come with. I replace both the tubes with real 60 watt tubes and the machines work great even in a commercial stetting. We run them 10-12 hours per day with no issues. I will probably buy a third one soon. 99% of our work is engraving client logos on veneered plywood. I was thinking of upgrading the lenses for lenses specifically designed for engraving. We do not do any photo engraving by the way. I believe these lenses have a smaller focus point. What type of lens do you think would be best for this and also what is the actual diameter of the lenses. I am having trouble figuring out what size to replace with. My apologies if you already went over this in one of your videos (as I am sure that you have) but I have not seen it yet. Thanks Russ!

[@SarbarMultimedia]

Hi Nate It's good to hear from someone that is really thrashing these machines. I only tinker and enjoy myself. I had 10 years running a profiling business with two 3kw metal cutting lasers. They were industrial machines whereas these Chinese machines are in a different league. I had to start learning from scratch because what I knew did not apply to these low powered sealed laser tubes. Its been a fantastic opportunity for me to combine my video hobby and my love of engineering as a retirement activity. I shall be very interested to know how long your tubes last and what you bought them as , standard or long life (10,000 hours) tubes. It all useful data that I can feed back into the community. Doing only engraving then you are really testing those X axis bearings. Even those Taiwanese bearings should last well. I do know a couple of others who are equally pleased with their machines in a commercial environment. Once you have been through the learning curve with one, adding more for capacity and backup in case of breakdown makes absolute sense. Anything serious like Epilog or Trotec is ten to fifteen time the price. Back to your question. I presume you are using the 2" focal length lens supplied. It all depends on the type of lens mounting you have in you machine as to whether you can even upgrade to a 1.5" focal length. There are two basic lens mount systems used in these machines. My Lightblade machine uses a system where the lens is mounted in the tube above the nozzle. If yours is like that then it will not be possible unless you can engineer a solution as I did with my Lightblade. If yours is mounted in the nozzle, the setting piece you have will almost tell you this. If the gap between work and nozzle is set to 19mm then you have a nozzle mounted lens. If so, it will be easy to remove the lens, measure its diameter (it will be any of 18,19 or 20mm diameter) to make sure you order the right size. HOWEVER, if you are only doing logos and letters on wood, I don't think you will see any benefit from a shorter focal length.. Engraving is a subject I have scratched the surface of during my 2 years with this machine. It is a huge subject with so many variables to understand. I have just started serious pursuance of the subject because so many folks are interested in getting photos onto various materials. I can get half decent results on some materials by the scatter gun approach but I need to understand the foibles of many materials, the limitations of the machine ,lens,speed, power. dots per inch for a given pixels per inch and the many parameters that are there to play with within RDWorks. Only then will I be able to home in quickly on a good result without all the trial and error.. The problem with many woods is the grain structure can take over a picture,. In your case with logos and text it's probably a great textural feature. The problem with wood is that because it is a soft material it burns very easily and it is almost impossible to burn a mark which is the same size as the focal spot potential of the lens. A 2" lens has a theoretical spot of 0.004" and a 1.5" lens a spot size of 0.003". In human eye perception terms I don't think you would ever notice the difference and on wood I'm sure that you would get better result with the 2" lens because , although the energy density is half that of a 1.5" lens. the burn will be softer and more controllable. I'm not saying you are wasting your time trying a 1.5" lens but you may see no benefit with the materials you are using and the type of engraving you do. For about $20 from China, it's worth a trial. Don't bother with an HQ lens, the performance difference is negligible for almost twice the price. Just go for a ZnSe lens. Hope this helps abit All best regards Russ

[@maaloufdany]

Hi Russ, just a question, are these gold mirror polished?

[@SarbarMultimedia]

Hi Danny These mirrors were lapped very flat by a metrology company who brought them up to a reasonably reflective finish. To get an extra 2% out of then I had to carefully "shine" them. The sets I sent to US were the lapped but unpolished ones because I was hopeful that gold, like copper had an inherent reflectivity in its crystal structure, The plating seemed to improve the finish and they were very nice gold mirrors.....just not as expected. Although gold does not tarnish, it is very soft and will easily be damaged if much cleaning is attempted. I think fate is steering us towards moly mirrors. Best regards Russ

[@maaloufdany]

Thank Russ for your prompt reply, it's been very helpful as all of your videos, btw do you know that i'm following your videos half away across the glob from the middle east (Lebanon)? thanks for the great job you are doing, thumbs up! best regards, Dany.

[@SarbarMultimedia]

Hi Danny Thanks for the kind words. I'm just an old guy with a techno toy in his man cave. I have a second hobby which is video (an editing) and I was running out of subject matter. Learning to use use this mysterious Chinese dragon seemed like the perfect video opportunity to document my experiences. Still far to go. I am amazed that something so niche would have followings in every corner of the globe. Best wishes Russ

[@Remoteflyer]

Nice and concise. That's that then. Thanks.

[@Chupria]

And at the 0:33 mark , the supporting actor (his decorated left hand) appears just in time.

[@Rob-wl8dy]

hello Russ. Great series... i watched all the videos few times and started the same adventure few days ago. How can I contact you? i'd like to purchase your laser power measuring device. regards Roberto

[@SarbarMultimedia]

Hi Roberto Send me your email via the You Tube private messaging system and I'll send you all the information Best regards Russ

[@GrowMau5]

Hey Russ & Commentors. IMPORTANT!!!! as of July 2018 DO NOT ATTEMPT to visit Fresno Sim Flight simulator parts website. It has unfortunately been hacked with malicious spyware and will lock down your computer. shame. Going down the mirror rabbit hole on my "50w" china blue. Thanks for the amazing videos as always.