# Phil's 2.8w Jtech Laser Journey **URL:** \ **Category:** Upgrades\ **Created:** [October 16, 2017, 9:31pm UTC](https://community.inventables.com/t/phils-2-8w-jtech-laser-journey/43814 "2017-10-16T21:31:44Z")\ **Posts on this page:** 20\ **Page:** 0
**Author:** ![LarryM](https://yyz1.discourse-cdn.com/flex009/user_avatar/community.inventables.com/larrym/32/51450_2.png) [@LarryM](https://community.inventables.com/u/LarryM)\ **Post date:** [October 16, 2017, 10:09pm UTC](https://community.inventables.com/t/phils-2-8w-jtech-laser-journey/43814/2 "2017-10-16T22:09:19Z")
Phil, take a moment and figure out what your primary use for the laser is going to be. Depending on what you want to do the 2.8 W unit might be a better fit to your job than the 3.8 W unit. ---
**Author:** ![LarryM](https://yyz1.discourse-cdn.com/flex009/user_avatar/community.inventables.com/larrym/32/51450_2.png) [@LarryM](https://community.inventables.com/u/LarryM)\ **Post date:** [October 16, 2017, 10:40pm UTC](https://community.inventables.com/t/phils-2-8w-jtech-laser-journey/43814/4 "2017-10-16T22:40:19Z")
Bigger is always better, right? Using the numbers on the Jtech site: 2.8 W has a spot size of 0.009 inch 2.8 / PI \* (0.009 / 2) ^ 2 = 44013 watts per square inch 3.8W has a spot size of 0.015 inch 3.8 / PI \* (0.015 / 2) ^ 2 = 21503 watts per square inch You actually get higher power density (hotter spot) at the material with the smaller laser (with a smaller spot - good for engraving detail). Others with experience with the laser diodes can chip in here, but you will not be happy trying to cut materials with any laser diode. The Opt people have a good web page (keep in mind these test were done with a 6 Watt laser your results would be roughly twice (3.8 w laser) as many passes to do each cut). They used to give times, but I see that they have changed that (really pointed out how slow cutting is). Very thin materials. > **[Laser Heads for CNC Engraving ⁎ Laser Systems, Drivers, Modules, Diodes -...](https://optlasers.com/)** > > European manufacturer of laser systems, modules, and electronics. Laser solutions for science and industry. E-shop: laser components, engraving laser heads for CNC machines. PLH3D series - laser heads for CNC, engraving, 3D printing. Accessories,... ---
**Author:** ![LarryM](https://yyz1.discourse-cdn.com/flex009/user_avatar/community.inventables.com/larrym/32/51450_2.png) [@LarryM](https://community.inventables.com/u/LarryM)\ **Post date:** [October 16, 2017, 11:41pm UTC](https://community.inventables.com/t/phils-2-8w-jtech-laser-journey/43814/6 "2017-10-16T23:41:25Z")
> [@RobertCanning](#): > > he has the 3.8 and it does burn faster. When you say faster, do you mean the same job will complete in less time with the 3.8 rather than the 2.8? And, is that just because the 3.8 burns a wider path than the 2.8? ---
**Author:** ![alvingm](https://yyz1.discourse-cdn.com/flex009/user_avatar/community.inventables.com/alvingm/32/45992_2.png) [@alvingm](https://community.inventables.com/u/alvingm)\ **Post date:** [October 16, 2017, 11:46pm UTC](https://community.inventables.com/t/phils-2-8w-jtech-laser-journey/43814/8 "2017-10-16T23:46:02Z")
Tried cutting a 3mm birch with my 3.8w JTech before, it took at lot of passes and sides are pretty charred. Jay said air assist might help but not much. I have not tried it with air assist though ---
**Author:** ![LarryM](https://yyz1.discourse-cdn.com/flex009/user_avatar/community.inventables.com/larrym/32/51450_2.png) [@LarryM](https://community.inventables.com/u/LarryM)\ **Post date:** [October 16, 2017, 11:59pm UTC](https://community.inventables.com/t/phils-2-8w-jtech-laser-journey/43814/10 "2017-10-16T23:59:06Z")
> [@RobertCanning](#): > > thats above my pay grade Larry but I always assumed it was simply higher power can make the same burn in less time The 2.8 watt unit delivers higher optical power to a thinner path than the 3.8 watt delivers a lower optical power to a wider path. Think this way 2.8 watt is smaller diameter mill with greater depth of cut capability and the 3.8 watt is like a larger diameater mill with less depth of cut capability… ---
**Author:** ![ErikJenkins](https://yyz1.discourse-cdn.com/flex009/user_avatar/community.inventables.com/erikjenkins/32/84368_2.png) [@ErikJenkins](https://community.inventables.com/u/ErikJenkins)\ **Post date:** [October 17, 2017, 12:14am UTC](https://community.inventables.com/t/phils-2-8w-jtech-laser-journey/43814/14 "2017-10-17T00:14:25Z")
One thing I did was to get a new lens for the 3.8w laser that gives me a much smaller focal point. I’ll find the link of the lens I used. ---
**Author:** ![LarryM](https://yyz1.discourse-cdn.com/flex009/user_avatar/community.inventables.com/larrym/32/51450_2.png) [@LarryM](https://community.inventables.com/u/LarryM)\ **Post date:** [October 17, 2017, 12:23am UTC](https://community.inventables.com/t/phils-2-8w-jtech-laser-journey/43814/16 "2017-10-17T00:23:07Z")
Just as a reference Phil, I have been quite surprised in reading the forums of people that use the K40 Chinese 40 watt CO2 laser cutter. Although, they do a much better job of cutting than a laser diode, I’m still not impressed by their cutting capability. ---
**Author:** ![LarryM](https://yyz1.discourse-cdn.com/flex009/user_avatar/community.inventables.com/larrym/32/51450_2.png) [@LarryM](https://community.inventables.com/u/LarryM)\ **Post date:** [October 17, 2017, 12:25am UTC](https://community.inventables.com/t/phils-2-8w-jtech-laser-journey/43814/18 "2017-10-17T00:25:07Z")
> [@PhilJohnson](#): > > Hopefully it will engrave like I want! You’re going to get hooked on doing laser images. ---
**Author:** ![DavidLovely](https://avatars.discourse-cdn.com/v4/letter/d/a3d4f5/32.png) [@DavidLovely](https://community.inventables.com/u/DavidLovely)\ **Post date:** [October 17, 2017, 12:36am UTC](https://community.inventables.com/t/phils-2-8w-jtech-laser-journey/43814/19 "2017-10-17T00:36:35Z")
@ErikJenkins What lens was that? I ordered this [lens](http://www.ebay.com/itm/445nm-450nm-462nm-465nm-Blue-Glass-Collimating-Lens-M9P0-5-Metal-Frame/261157555202) for the 3.8w but have been unable to get it to focus. It seems to make a 1" long rectangle. I can get a smaller focal point but its at the very end of the threads and falls out with any movement. ---
**Author:** ![ErikJenkins](https://yyz1.discourse-cdn.com/flex009/user_avatar/community.inventables.com/erikjenkins/32/84368_2.png) [@ErikJenkins](https://community.inventables.com/u/ErikJenkins)\ **Post date:** [October 17, 2017, 12:37am UTC](https://community.inventables.com/t/phils-2-8w-jtech-laser-journey/43814/20 "2017-10-17T00:37:42Z")
It sounds like the lens is in backwards. Edit: I purchased a 3 element lens. I did the same thing when I swapped out the lens…reversed it and focus was easy 🙂 ---
**Author:** ![DavidLovely](https://avatars.discourse-cdn.com/v4/letter/d/a3d4f5/32.png) [@DavidLovely](https://community.inventables.com/u/DavidLovely)\ **Post date:** [October 17, 2017, 12:41am UTC](https://community.inventables.com/t/phils-2-8w-jtech-laser-journey/43814/21 "2017-10-17T00:41:42Z")
I installed it with the threaded end in first. I have not tired it with the notched end in first. ---
**Author:** ![ErikJenkins](https://yyz1.discourse-cdn.com/flex009/user_avatar/community.inventables.com/erikjenkins/32/84368_2.png) [@ErikJenkins](https://community.inventables.com/u/ErikJenkins)\ **Post date:** [October 17, 2017, 12:43am UTC](https://community.inventables.com/t/phils-2-8w-jtech-laser-journey/43814/22 "2017-10-17T00:43:24Z")
mine had a threaded housing (brass end) I unscrewed it from the brass ring…flipped it…it is a apparently common error. ![s-l500](https://cdck-file-uploads-canada1.s3.dualstack.ca-central-1.amazonaws.com/flex009/uploads/inventables/original/3X/b/6/b6fdc5683bb5b3f42860d1e5931c2d8da0fda6ee.jpg) This is how mine came…I took off the ring and put it on the other side… ---
**Author:** ![RyanEdwards](https://yyz1.discourse-cdn.com/flex009/user_avatar/community.inventables.com/ryanedwards/32/38826_2.png) [@RyanEdwards](https://community.inventables.com/u/RyanEdwards)\ **Post date:** [October 17, 2017, 12:48am UTC](https://community.inventables.com/t/phils-2-8w-jtech-laser-journey/43814/23 "2017-10-17T00:48:00Z")
Also curious about the lens. I have the 3.8 and have not used it much because it takes too long to do anything other than line art… Maybe I still don’t have my settings right or haven’t focused it properly but it took a good 8-10 passes at 40ipm to cut through some thicker cardboard and text outlines are the only thing I can accomplish unless I want it running all day. Seems if I run any faster than 40ipm it doesn’t come out well. ---
**Author:** ![RyanEdwards](https://yyz1.discourse-cdn.com/flex009/user_avatar/community.inventables.com/ryanedwards/32/38826_2.png) [@RyanEdwards](https://community.inventables.com/u/RyanEdwards)\ **Post date:** [October 17, 2017, 12:49am UTC](https://community.inventables.com/t/phils-2-8w-jtech-laser-journey/43814/24 "2017-10-17T00:49:26Z")
So flipping it may work better? ---
**Author:** ![ErikJenkins](https://yyz1.discourse-cdn.com/flex009/user_avatar/community.inventables.com/erikjenkins/32/84368_2.png) [@ErikJenkins](https://community.inventables.com/u/ErikJenkins)\ **Post date:** [October 17, 2017, 12:51am UTC](https://community.inventables.com/t/phils-2-8w-jtech-laser-journey/43814/25 "2017-10-17T00:51:11Z")
No, if you are cutting at all you have the lens in correctly. These laser just do not cut well at all. They are primarily for etching and they do a great job at that. ---
**Author:** ![ErikJenkins](https://yyz1.discourse-cdn.com/flex009/user_avatar/community.inventables.com/erikjenkins/32/84368_2.png) [@ErikJenkins](https://community.inventables.com/u/ErikJenkins)\ **Post date:** [October 17, 2017, 1:06am UTC](https://community.inventables.com/t/phils-2-8w-jtech-laser-journey/43814/26 "2017-10-17T01:06:28Z")
If you are having a problem getting a good focus, I found using a piece of black anodized aluminum makes it much easier to see the focal point. I use a piece 0.5mm thick, focus on that piece while it is resting on the material I am etching. Then drop the z axis 0.5mm and I am good to go. ---
**Author:** ![BrianSaban](https://yyz1.discourse-cdn.com/flex009/user_avatar/community.inventables.com/briansaban/32/84709_2.png) [@BrianSaban](https://community.inventables.com/u/BrianSaban)\ **Post date:** [October 17, 2017, 2:33am UTC](https://community.inventables.com/t/phils-2-8w-jtech-laser-journey/43814/27 "2017-10-17T02:33:50Z")
I got this guy, it’s 40watts and not enough power for me 🕶 Don’t forget to wear laser safe glasses with those open models and make sure you learn what **NOT** to cut or engrave with a laser, like vinyl (it can easily kill you). ![download (1)](https://cdck-file-uploads-canada1.s3.dualstack.ca-central-1.amazonaws.com/flex009/uploads/inventables/original/3X/3/8/389ab826a88a4c6154e24d517d47cc807e50796a.jpg) ---
**Author:** ![LarryM](https://yyz1.discourse-cdn.com/flex009/user_avatar/community.inventables.com/larrym/32/51450_2.png) [@LarryM](https://community.inventables.com/u/LarryM)\ **Post date:** [October 17, 2017, 4:01am UTC](https://community.inventables.com/t/phils-2-8w-jtech-laser-journey/43814/29 "2017-10-17T04:01:00Z")
Be sure to set things up so that your kids (or anyone else) can’t walk in while you’re working the laser. ---
**Author:** ![LarryM](https://yyz1.discourse-cdn.com/flex009/user_avatar/community.inventables.com/larrym/32/51450_2.png) [@LarryM](https://community.inventables.com/u/LarryM)\ **Post date:** [October 17, 2017, 4:08am UTC](https://community.inventables.com/t/phils-2-8w-jtech-laser-journey/43814/31 "2017-10-17T04:08:52Z")
JTech does have some inspection window filters, but they are small. You have to worry about reflections as well. When I put my laser setup together it will be totally enclosed with an inspection window filter. I’m pretty paranoid about this. I’ve worked with lasers for a lot of years in other applications. It’s so easy to make a mistake that cannot be undone. ---
**Author:** ![AlanDavis](https://yyz1.discourse-cdn.com/flex009/user_avatar/community.inventables.com/alandavis/32/4710_2.png) [@AlanDavis](https://community.inventables.com/u/AlanDavis)\ **Post date:** [October 17, 2017, 5:15am UTC](https://community.inventables.com/t/phils-2-8w-jtech-laser-journey/43814/32 "2017-10-17T05:15:46Z")
That’s what your Last name stands for, got it. 🤨 [Next page](https://community.inventables.com/t/phils-2-8w-jtech-laser-journey/43814.md?page=1)