Bought a brand new 20W Fiber Laser and feel completely lost - help?

[Alex Smith23]

Hi everybody. Long time listener, first time caller.

I just took ownership of a 20W Chinese JPT fiber laser. I've owned a CNC hobby machine in the past so I didn't fear the learning curve with the laser would be too different. I've been playing around with the laser for two nights, but feel completely lost. This machine came with some parameters from the manufacturer (see attached pics), but I can't seem to get the machine to mark my 304 stainless steel consistently. For a little bit I was able to get some markings on my 304, but this evening I can't. The laser seems to move around and mark, but nothing appears.

So far I've:

1. Made sure the distance between the galvo and material is 295mm (distance it tells me on the galvo)
2. Aligned the two red dots (really part of #1)
3. Set Ezcad parameters to what the manufacturer gave me

Surely I must be missing something. At this point I'm seeking a mentor to help me get started and would even be willing to pay somebody to help me out. Any takers?

[Gary Hair]

The measurement on the lens isn’t the distance to the material. Draw a small square and place it directly in the center of the drawing page. Check “continuous”, and set power to 100, speed to 300 (metric), and frequency to 30. Start with your distance at 295 and click run. Move the galvo head down until you get the brightest flash with the tallest sparks. You may have to move it quite a ways down to get there, but keep going until you get this result. Click stop and measure the distance - that is your focus distance.

[Bill George]

Surely I must be missing something. At this point I'm seeking a mentor to help me get started and would even be willing to pay somebody to help me out. Any takers?

What you can do for Free and I did if Before I even ordered mine was spend a few days/weeks Searching and Reading on here. Lot faster than posting a Question and waiting for if and when someone came on with the Answer.

[Kev Williams]

This should get you in the ballpark on focus distance---

According to your first photo, you have a 175mm lens. I have a 160, and have my focus dialed in perfect.

So what I did was draw a 2" (50.8mm) square, and measured the red box with my dial calipers, measured dead to rights 2".

So I went into my parameters and changed my 160mm number to 175mm. Just doing this makes the machine recalculate what 2" should be with a 175mm lens. I had to lower my table nearly an inch to get the square to again measure 2". Then I took my digital 12" calipers and measure from the edge of the lens collar to the top of the table.

I got 279mm, or 10.984", whichever works best for you

Cut yourself a piece of something- small dia dowel rod, some scrap Rowmark- to exactly 10.984" and use it as an intial focus tool. Use the COLLAR of the lens, NOT the glass as the reference point.

This should put you very close. Gary's suggestion will get you fine tuned - When you ARE fine tuned, tweak your focus tool.

The red-light focus is okay, but needs occasional adjusting and isn't that close anyway. A physical ruler of some sort is always more accurate.

[Jacob John]

Welcome to the world of fibers! We're all guinea pigs in this game. I have a stack of ruined test materials that could likely be enough to build a stainless steel car.

[John Lifer]

For my Ray fine, they gave me a measurement for my two lenses focal lengths, it was from item up to the separation of the head sections. Would be higher than the lens. But it works and this seems to be your issue. Yes, go searching and read and read some more. The manual is good too.

[Alex Smith23]

The measurement on the lens isn’t the distance to the material. Draw a small square and place it directly in the center of the drawing page. Check “continuous”, and set power to 100, speed to 300 (metric), and frequency to 30. Start with your distance at 295 and click run. Move the galvo head down until you get the brightest flash with the tallest sparks. You may have to move it quite a ways down to get there, but keep going until you get this result. Click stop and measure the distance - that is your focus distance.

Gary, Thank you for the quick response. I did as you suggested, but to no avail. It's as if the power on my laser isn't strong enough to make a mark. Are there some other settings that I may have missed?

[Neville Stewart]

https://youtu.be/o_jg02Zgfm4

As you see, this is the hazard version of what Gary & Kev told you but try it and then re-read G&Ks posts.

[Gary Hair]

https://youtu.be/o_jg02Zgfm4

As you see, this is the hazard version of what Gary & Kev told you but try it and then re-read G&Ks posts.

. That video shows exactly what I suggest but I would use a small (.25") square instead of text and I'd use stainless instead of aluminum.

[Bill George]

I suggest contacting your vender, my Ray Fine machine came with the files already set up for both my lens, and a nice stainless metric ruler and measurements noted in the set up instructions. My measurement index is from the center line of the galvo housing. Easy, Peasy.

[Neville Stewart]

When you find your focus, make yourself an isosceles triangle that the close corner side rests on the lens edge. Better than a single point contact.

[Alex Smith23]

https://youtu.be/o_jg02Zgfm4

As you see, this is the hazard version of what Gary & Kev told you but try it and then re-read G&Ks posts.

This video is more or less exactly what I've tried along with setting speed to 11.81 inches (Gary said 300mm, but I changed my preferences to inches), power to 100, and frequency to 30. I changed the height of the galvo head from as high as it would go to as low as it would go to no avail. Tried marking on 304.

[Kev Williams]

I've always thought engraving the same thing over and over to be counter productive to finding good focus, in regular use I notice different spark and light characteristics going over same place more than once. So I went into Corel and drew up a 2" spiral and imported it in...
spiral.jpg
run at 200 or 300 speed, it takes a long time to finish, and nothing is engraved twice until it does, always a 'virgin' burn...

And IMO using 100% power to focus-test is also counter-productive, learned that from ramp testing. Rather, I use very low power, which when in focus, the beam will just barely make a mark. It's MUCH easier to find or notice THE mark than trying to discern the brightest part of a mark or the brightest flash while the mark is being made. For my C02 machines I ramp test at 5% power, and just draw a straight line. The only mark that shows is less than 1/4" long, I take my measurement from the middle of that 1/4". For the fiber I started at 20% power and located the focus range the beam would mark, then lowered the power and re-tested until I got the distance dialed in to within around .010" or so.

[John Lifer]

One thing I suspect is your focal distance should be well over 295mm from surface to case divide with this lens. Taking ratio of my two lens, I think it should be 375mm. And with JPT fiber, you shouldn't have a q pulse showing if set up like my machine. I'd be asking for full configuration settings.

Now one other thing I remember about my setup is that I had to reset the external focus red dot. Mine had been bumped and once I got into focus (burning best spot) I reset it. Don't depend on it being in exact right position.

[Kev Williams]

with all due respect, a 375mm focus distance doesn't work, that's over 14.6" inches-- the distance between my lens housing and the bottom of the machine is only 15-1/2"-- add in the height of the scissor table that came mounted and a 375mm focus distance would be well below the top of the table when full down. I have a black line drawn across the front of my machine at my focus distance (quick visual reference), and that line is 5.46"/139mm above the bottom of the machine. I'm using a 160 lens, Alex is using a 175, my focus stick is exactly 9.747"-- going to 14.6" is a 50% increase in focus distance for only a 15mm lens jump, that can't be right--

Alex- if you're getting zero marking at any distance, you have something else going on, could be the laser's actually not firing for some reason...