So it looks like you may have misunderstood my instructions for moving and adjusting the lens. By the looks of the pictures you have loosened the set screw that holds the copper laser tube in the heatsink with the thermal paste. Your laser is now falling out of the heatsink. This is not good. You need to loosen the set screw on the top of the heatsink and push the copper tube back into the laser heatsink until it is flush with the front of the heatsink. It used to have thermal paste on it, but it looks like it has been removed.
From the last picture it looks like the brass lens holder is pushed all the way into the laser tube. This will not produce a spot that is small enough to burn. There should be about a 1mm to 2mm distance between the silver outer thumb screw ring and the front of the heatsink (or the copper laser tube). I attached a picture showing a properly focused laser on our lab machine.
I may just need to swap out your laser for a new one that is “pre set” for focus for you at 3". Let me know if this is how you want to proceed or if you think you can get it fixed on yours.
When I received my laser from Jay the thumb screw was to tight and when I tried to adjust it the brass tube unscrewed. Once I realized this I got them apart and threaded the tube into the heat sink and was finally able to adjust the focusing lens.
Take your time and really pay attention to see what is turning. Once you get it adjusted you will have loads of success with a great product.
Curt
Hi Alvin- Great news! I am not sure what happened on the first go around, but I am glad to see you are up and running! I really like the protective shield around the laser as well. Nice work!
Jay
has anyone tried cutting a 1/8" craft plywood with either a 2.8 or 3.8 laser? I think it’s birch. Tried tons of settings I was able to cut once but the sides were pretty charred.
I used the laser mount with the line laser holder for Universal Mount (http://www.thingiverse.com/thing:1025450). I removed the laser holders (just manually break them by hand :)) and created a very crude holder for the shield that mounts on top of the fan. I just started using Fusion 360, I actually tried modifying that mount directly but I think I just maxed out my knowledge when it comes to creating/modifying a model ?? I cut the shield from JTech and make sure the length is almost 3" so using that as my gauge as well
EDIT: I attached the .STL and here’s the Fusion 360 project if you want to try it (http://a360.co/2e0NNv4)
We cut through the Home Depot Birch plywood with the filler in the middle on the 3.8W laser at 150mm/min with 5 passes. We have a shop vacuum attached down by the work surface to suck up the smoke where the cut is made. This helps with reducing the amount of char and makes the efficiency of the laser better for cutting. There will be less flare up and the laser light will not get reflected off the smoke coming off the cut. I think without the vacuum (or other air assist system) cutting hard woods is going to be difficult. The 1/8" built up hobby plywood (multiple sheets of Birch) is going to be very tough to get through. I have seen people accomplish it, but I think they had a vacuum or air system as well.
Jay
I have the 2.8W unit which I think is more of the issue. I assumed that when I bought this I could cut 1/8" plywood but I should have bought the 3.8W instead.
Curt
Would a normal analog ammeter in line along the positive laser wire between the driver and diobe be the correct way to measure the amperage pulled by the laser?
While I don’t normally recommend using a meter in the output path, an old school analog meter is the best bet. The digital ones tend to “sample” the signal and cause noise when this occurs. If you want to use the test points on the side and make a micro-controller solution here is the blog post on it: https://jtechphotonics.com/?p=1379
Has anyone designed a mount that bolts directly to the MPCNC Z gantry using Ryan’s universal plate. The popular one seems like you have to pull the universal mount off the 3/4" pipe.
I was able to cut once but the sides were pretty charred.
