Laser Cutter Focus - Measuring Focal Point and Depth of Cut

[@pissantsseemore7095]

Best explanation in 3-years laser video searching

[@sariddle]

Great info and description of what is going on with the lens and focal point but the best I think is how you use your laser to draw your example. That is awesome and creative.

[@okinawanwarrior8689]

The way to remember whether flat side or curve side down, think of parabolic antenna dish like you see on the satellite tv receiver. All the rays are focused toward center of the dish (at some focal point from the parabola) to concentrate the rays at a single point. Flat side down so that rays leaving the lens gets bent inward toward center.

[@mikkosutube]

in summary..for this machine..a 38mm lens is good for cutting thin metal for example where you need high power focused in a small area..the longer lens is for making straight cuts in softer and thicker material..in between those two is a good general purpose lens..running tests at various depths allows you to determine the focal pont for fine detail work. Thanks for a great video!

[@thebeststooge]

This is from Boss Laser on this subject: 1.5" - Best for detailed engraving 2.0" - Good compromise between cutting & engraving 3.0" - Cut thicker materials and some engraving 4.0" - Primarily for cutting thick material

[@valmoyer6203]

i learned more watching 2 of your vids then 48 hrs of other peoples THANK YOU.

[@geminiman2831]

Can I use the preforated sheet for co2 laser bed? What is the thickness of the sheet used in your bed?

[@freddotu]

I've learned that the lens is called a plano-convex, which means one side is flat, unlike the diagrams in the video. The focus point is changed depending on which side is pointing to the work. It has been determined that the flat side of the lens should be on the work side. Inexpensive Chinese lasers are frequently shipped with the lens inverted.

[@makestuffnow]

You are correct. Beam goes in curved side, goes out flat side. If it is the other way around the focal point gets spread out more along the beam direction. My diagram shows just a generic lens, but in the machine I do have the lens put in correctly like you point out.

[@freddotu]

at 6:34, you reference the flat side, then state "curved down," hence my comment. Thank you for the video, as I've learned a few new things for laser alignment and will soon perform those checks.

[@makestuffnow]

Yeah I did say that wrong... Thanks for pointing it out, I'll add a caption or something.

[@pissantsseemore7095]

video diagram shows diagonal not end view

[@pissantsseemore7095]

you are incorrect. beam enters flat end is spot focused on curved. both need study optical physics. join the Boy Scouts for life experience

[@houstonfirefox]

Good explanation of the different focal lengths and when you would use one over the other. Very well done!

[@shahadipour]

Thank you so much you are the best person who explains in engineering language yet simple enough for everyone to understand not too much talking and not mute.

[@MikiZChannel]

How do I know what kind of Lense I have? It came with the machine of course but I do not know what type it is.

[@ElenaWilliams-elequ]

Terrific information. So glad you're concentrating on the actual highest impact part of the machine -- the focal point. Unlike so many other videos just dummying through alignment. Thanks for the proper research. Legendary work.

[@CisnerosShop]

Do you lower the head of the laser with a controller, some software, or adjusting the laser bed?

[@paulmicallef5990]

According to others, plano-convex lens work in both directions but due to aberration it should be oriented with the flat side toward the workpiece and the convex side toward the laser to get a smaller spot.

[@makestuffnow]

Put it in the correct way, and you get a smaller spot for finer engraving and higher power density for things like marking metals and hard woods. Put it in the 'wrong' way and aberration will stretch the working depth out just a little more at the cost of lower power density. Helps cut a bit deeper in acrylic which doesn't require such a high power density to melt through.

[@paulmicallef5990]

Thank for your reply. By the way, really good videos and well explained.

[@julioguzman5197]

Barely getting a 55watt co2 laser and I find this video great to get started on my acrylic work

[@Tekniques25]

With a plano-convex lens, THE CURVED SIDE GOESUP (toward the beam) and THE FLAT SIDE GOESDOWN (toward the work).In other words the laserbeam needs to pass through the curved part of the lens first. Lenses are typically referenced by their focal point. So it kind of voids the video. To be honest once your plywood started shifting up and down when you pressed on one of the corners when you were measuring the distance between the laser head and the wood with your super accurate tool you really threw the measurement off.

[@screeningstudio3868]

Does the laser tube power effect the size of focal length lens needed to be use?

[@leosbagoftricks3732]

Best video on the subject so far- thank you!

[@pieterleroux7889]

Should the PC lens not be installed flat side down?

[@makestuffnow]

Yes. I said it wrong and didn't realise until well after i put the video together. But even if you put it in the wrong way, for a narrow single wavelength beam like this it doesn't make a very big difference

[@jbrondos]

(1) Do you have design for making your adjustable bed? (2) Is it possible to replace the laser tube on a 40W Chinese laser with a higher wattage laser tube (e.g. 60W or 80W) without having to make any other modifications to the program, circuit board, etc.? If it is possible, where can one order such replacement laser tube?

[@makestuffnow]

1) Just a 3mm aluminium plate cut to shape. I wrote how I made it here goo.gl/6vYxW3 2) A bigger tube is longer and wont physically fit. But if you did manage to modify the case to fit it all the control stuff will work fine, the only thing you need to check is to make sure your laser power supply puts out enough current. I would just buy a new power supply along with the laser tube.

[@tassiespirit]

Curve side up for a standard lens.

[@mdeen9135]

Great video, however how does one work with engraving precisely with depth. Say I want my engaving to be exactly 1mm in one project and 2mm on the other?

[@M4R10_]

and about other kind of ✴️ laser like NEJE MASTER 20W. how can i descovery the focus range and deep cut effectiveness ?

[@makestuffnow]

those little solid state lasers have the lens attached directly to the laser unit. You can adjust the focus a bit by twisting the screw mount holding the laser, or by lifting or lowering the work piece. In principle it all works the same.

[@rvinayak7698]

Thanks for the explanation, can i cut 12mm MDF with 3" Lens ?

[@tassiespirit]

Always been told curve side up for best focus and curved side down for best power. Why do you use curved side down?

[@makestuffnow]

Yeah I meant to say curve up. That's how it is normal placed. Really though with the characteristics of the laser and what you are trying to achieve it makes very little difference how it goes in. Just be aware though that the way you put it in will affect the distance to the focal point by a few millimetres so either be consistent or make a separate focal point measurement for either orientation.

[@brian2k1]

The air nozzle looks adjustable right on the side. Was it included or did you add it later? I'd like to add that to my machine to get finer control on the air flow, right now I just have a 1/4" on/off fitting near the pump and at best you can do settings of on, half on, and off.

[@makestuffnow]

It came already fitted. Like the rest of the stock fitted air flow system, it doesn't work very well.

[@seckora]

What do you cut do you cut the foam for? I'm kind of interest in costuming and You really sparked my interest

[@makestuffnow]

Ive cut acoustic foam for making inserts for cases mostly, but also tried a few other foams which would be similar to costuming. You need to test materials first. Some foams and plastic types will just burn black instead of cutting nicely (very bad). As a quick test you can try bringing a lighter up to the material. If it just melts away it will probably cut nicely, if it burns brown/black it is not suitable to put in the laser cutter.

[@halilakgun3947]

Hello I bought a China (ebay) laser and have problems with MDF plates to cut with 3 mm thick of the workpiece, in contrast to set of hard plexiglas with 4-5 mm, the machine cuts well, where do I go wrong? what could you recommend to me? what distance do I have to keep from the workpiece, the position from the work table? Please, for a feedback, dake you ever in advance for your helpful answers. Best regards Halil Akgün

[@makestuffnow]

You should be having no trouble cutting 3mm MDF with any lens. Set the distance from the nozzle to the workpiece exactly where the focal point is. If this distance is set correct you should be cutting through 3mm easily. Make sure the airflow from the nozzle is working ok.

[@JoBeelen]

Super interesting video, thank you for sharing your knowledge! I recently bought a 60w laser, I'm definitely going to try this focus method. How can I find out what kind of focal length the pre-installed lens has?

[@maggidawson]

Hi, wondering if you could help. I have a piranha 5060 that ive just bought. got it set up and laser aligned, thanks to your videos and others on KZbin :) sent a test file to the laser and when i click start it says not enough extend space? have you any idea what this means and how I could fix it? Thanks Maggi

[@makestuffnow]

You're trying to engrave a bmp/png image file. When the laser scans left to right it needs a bit of space to accelerate up to speed first. So if you have your image too close to either the left or right of the table, the laser has no room to get it's run up, and gives the 'not enough extended space' error. Move your image about 1cm away from edge and it should then work ok. At least that's how the chinese ruida brand controllers work.

[@linzero3664]

1:26, light passed trough lens doesn't CURVE to and beyond the focal point. Actually light doesn't curve at all.

[@terrybrockhoff8168]

My manual says curved of lens to face up

[@btomas225]

Umm, Curve down? Shouldn't the lens be installed "belly up" or curved side up?

[@thebeststooge]

I am finally up and running and I just replaced the Blue Turd power supply with a HY-T60 and night and day difference. It matters and these Chinese "eBay" Laser manufacturers use seconds, and thirds, anyway so you are getting rejects to begin with. Buying something made by an ISO9001 factory vs some guys in a vacant building matters a lot.

[@kingsmanarmscorp6077]

hi, i have a problem with my laser is there somewhere i can contact you to see if you could help. thank in advance.

[@makestuffnow]

email address is in the about section on my channel page. Happy to help you out.

[@kingsmanarmscorp6077]

@@makestuffnow thanks brother. when i click the about section of your channel it shows empty. anyways shoot me an email and ill respond to it please. [e-mail]

[@jrtx]

Very useful information. And brilliant idea using the laser itself to draw the details! :)

[@mariosantos6319]

Hello I bought a China (ebay) k40 laser and have problems to engraving with the same intensity from right to left. When it goes to the right it does not engraving with the same intensity, it seems that the laser loses power in the right. It will be because of the alignment of the laser / mirror? Thanks for some tips :)

[@makestuffnow]

Very likely it is a mirror alignment problem. Another possibility is the cutting surface isn't level, but has a slight slope to it which you need to fix.

[@mariosantos6319]

Thanks a lot for your time, well, from what I've seen and analyzed it should be a mirror alignment problem.

[@kirisakichitogee]

Placing the material at an angle makes it easy to find the desired focus.

[@Chidoc]

seeing your calibration board wobble under slight pressure, makes any adjustment nearly pointless, or am i wrong?

[@makestuffnow]

Things are only shaking sideways mostly due to play in the screws holding the table bed. The up/down distance isn't changed once it settles back so it won't have any affect on trying to test the focal length.

[@FBI43]

hi, I can discreetly use the software, but the machine does not respect the characteristics described in the listing on ebay. I can work well with wooden materials, paper and cardboard. But there is a big problem for me and for my job: the machine is not able to work the methacrylate (plexiglass) WHY? on youtube we can all use my same settings and the same damn car! maybe it has factory problems?

[@makestuffnow]

That is strange because plexiglass should be one of the easiest materials to cut. I would need to see how the laser is marking the plexiglass. Feel free to email me. Email address in 'about' tab on my channel page

[@dr.premiumomar4771]

My machine cuts smaller than the order I give for example I give the order for a 4cm*4cm square it cuts it 3.8cm*3.8cm anyone can help me ???

[@ianschutt6242]

Great video thanks! Are you still cutting and making videos?

[@SciStarborne]

You've got me wondering about building a little carousel/turret plate to manually select between three different lenses rather than having to remove them entirely to change over. Something with a nice little detent for positioning and a locking clamp.

[@makestuffnow]

I like that idea! I think a bulky carousel might get in the way and bump into things, but some system with magnets and guide pins so you can quick-change different lens tubes would be great. I really like it. If I get around to making it up myself I will be sure to credit you with the inspiration :)

[@SciStarborne]

@@makestuffnow I'd really be interested to see how it turns out with magnets! Guide pins might certainly help resist them shifting under the accelerations used in engraving. Clearance issues are certainly something to look out for as well as not adding too much mass to the head. It might be that it'd only work well with a smoothieboard brain swap or similar where you can tweak the acceleration rates. But most of the large Chinese cutters I've been looking at seem to have plenty of mechanical clearance. Thinking of something like how you change magnification on a microscope. I'm also thinking of this for a community makerspace laser though, so don't know if I'd trust people to be able to physically remove the lens assemblies to swap them!

[@howtofixyourosx1978]

Can you also make a tutorial regarding - optimizing the engraving settings? The fokus of our laser is fine and everything but the engraving is just not very much on point...

[@makestuffnow]

Im going to film a few things while I install a bigger laser tube this weekend. I may do some tips on cutting various materials as well.

[@allan4317]

Between this video and your mirror alignment video, you helped clear up how the laser actually works. In your summary at the end, you state the 2" lens is the best GP lens for cutting 6-8mm hard materials. What is the wattage of the laser for these types of cuts. (eq. Baltic birch)? I'm leaning towards 60W right now. And as always, thank you for the time and effort you put into your videos.

[@makestuffnow]

My laser is 50W. That is just good enough to start cutting up to 8mm deep in softer hardwoods provided everything is aligned and set up well. 60W will make things much easier, 80W even better. Just depends if you have the money and the space to put the larger machine.

[@jimbauer6822]

both sides of lens is curved the concave side goes down the convex side goes up convex is the side curved up the concave is side curved inward

[@lasercuttemplate6595]

Thanks for the video! Friends, are people to whom here models are necessary for laser cutting?

[@JonDotExe]

What software are you using to generate the number and lines so quickly?

[@makestuffnow]

I just drew the lines and numbers in the control software RDWorks. I made each line/number a separate colour/layer so I could quickly choose which individual ones to sends to the laser.

[@fine2dream1]

Thanks for the detailled informaton! Will help many laser opreators. Indeed these Chinese machines are built rather sloppy, you can easily detect how the table is moving unequally and side to side when adjusting the height. But still, a good adjustment will improve work results.

[@makestuffnow]

funny thing is even though it shakes a lot, it always would fall back to the same place. Ive since tightened up those joints so it is not so sloppy, but it was never really a problem I needed to urgently fix.

[@hanspijpers2100]

nice idea, but I saw someone (forgot who it was) use a different system , he tilted the plywood at one side, burnt a hor. line and looked for the thinnest piece of that line, there he measured the ideal length, with a heme made step gauge meter or a wedge . kind regards Hans

[@zoo98513]

Curve is down, is this right ?!

[@Lennings82]

but the drowning is not good. the light beam is not bent. goes like a X with the burn mark in the middle. but the angle is different. so with with different focal length(linses) the X will be more draged out in the high. that way you get a longer cut before the spot become so big that the energi is not big enough to still cut. So in other words, how fast the sport grow/Distance.

[@makestuffnow]

The drawing is correct for a gaussian shaped beam. The intensity profile does curve like shown in the diagram. Look up information on 'TEM00 mode' if you want all the technical mathematics behind it.

[@Lennings82]

makestuffnow! Never heard about. Will take a look .👍

[@1designm923]

Thanks for the Super Instructional Video composition!!! The added laser engraving video detailing your instruction is the best ! I love it......Definitely took a lot of work on you r part!!! Good day Mate! Matthewwwwwwwwwwwww

[@neatpleats11]

Best tutorial ever

[@brianfoster1504]

It would have been better if the board had been made flat to the metal surface. As it is, the bowing in it is enough to make the entire exercise less than optimal. You can clearly see that the board has at least 5mm between bed and center of board, yet, when he measures, he pushes the board down, which affects the overall results.

[@edsapp7842]

Thank you. Interesting. I have never seen this explanation before and I have been using my laser for 8 years. I have a much better understanding of the cutting procedure's.

[@soniakarkera847]

Great Explanation. I want to ask that my machine is cutting great, but while Engraving it is only working good with x-unilateralism which engraves one sided (left), and that takes double the time. Can you please suggest some solution so that it would work good with x-swing also which engraves two sided (left and right)?

[@Rommelioh]

You need to compensate the backlash, had to adjust mine to -0.3

[@Rommelioh]

www.instructables.com/id/How-to-Improve-Engraving-Quality-of-Laser-Machine/

[@dariuszscharsig568]

Jesus christ that is some excellent editing!!!

[@avcomth]

At 06:42 you said the wrong word. The lens should be placed CURVE UP!! (flat down)

[@sylvaingenevay3147]

Really great when you start and just get nothing about it :) thanks a lot

[@7jmnplaylist253]

Great video, not just how, but why - top work thanks

[@manic9816]

do you any email so i can reach you? i hjave a couple of question and i hope you can help me.

[@makestuffnow]

check the 'about' tab on my channel page. email address there. I'm happy to help

[@z08840]

wow, there should be an incredible gravity along the ray to make light bend like that...

[@derek2593]

ALMOST great advice.... Some of it is machine independent. As Goku would say, "what is your power level?" Your advice is only good for the specific power of your laser, so what is it?

[@Jakefrc]

Thank you for a super informative video!

[@maggidawson]

Thank you for replying. Did that and it works perfectly now 😁

[@rickmccaskill7888]

What a great explanation. Thank you.

[@bgaworkshop7209]

Very good explanation and useful information, thank you

[@airstuff1874]

Thank you your video has been very helpful for me

[@GeorgeIndustry]

No funciona el link @t

[@ElevatedEngraver970]

Very Informative, Thank you very much for this information !!

[@mikenuke]

absolutely perfect explanation! thank you!!!

[@Someoldguycoding]

Very interesting and informative! Thanks!

[@paulfoster3491]

Some Old Guy Coding the

[@FuturefabOrgUk]

Fancy seeing you here!

[@sunlec]

Very informative. Thanks!

[@nebiaydogdu48]

Very interesting and informative! Thanks!

[@gracebyseven]

GREAT video, thank you! BTW love the cutting visuals to learn LOL

[@gezer2u]

thanks for taking the time!

[@higherperspectivephotography]

Very helpful. Thanks!

[@beyonddeath123]

Til lasers defy all the stuff I studied in physics. Curving light. Who knew

[@franciscojacome2420]

Very good video I learned so much tanks your cooperation!! I t is no easy to find good explanations on this matter.

[@hexahelix]

Thanks again.

[@davidfarish4076]

The top left corner of the material you are using is moving up and down every time you touch it. You are no better than the ones that you criticize.

[@davidmiguez9447]

Thanks, you save me

[@user-zq6pj5jo8j]

HOLLY VOLUME BATMAN..!!!

[@alg4633]

Dude, why bother with all of this. Why not just do a ramp test?