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View Full Version : Between Two Lasers - part 1



Trey Tull
12-28-2018, 8:23 AM
I'm sure this will be a multipart series that logs my failed attempts and observations at learning a mopa fiber.

I do a fair amount of long range / PRS style shooting. We recently setup a target at 1 mine (1760 yards) and everyone that we have tried hitting it, has connected. We wanted to give those people a challenge coin for hitting the target (24"x48"), so last night, I got busy making one. I sliced off a .173" thick piece of stainless bar stock and came up with a design. Below are my thoughts from the failed attempt to do it with the fiber.

1. I put on my 70x70 lens and for some reason, when I draw a 70mmx70mm square and hit the red button (ez cad software) the square that is shown is like 6mmx6mm. :confused: It shows correctly in the software but for some reason the fiber is shrinking it WAY down. If I set the box to 700mmx700mm and hit the red button, it will make a box alittle over 30mm.

2. After more than 4 hrs engraving on the coin, I was barely able to get .001" depth out of it. My last settings were 50s, 100p, 31khz, 250ns with a .01 (0, 90, 135 hatch). It was very very frustrating b/c sparks were coming off of it like it was being welded on but I just wasn't able to obtain any real depth. :mad: I was hoping that with time, I could obtain some real relief in the coin.

3. I'm glad I made the coin so thick b/c now, I can put it back in the mill and remove last nights failed attempt. :D

Kev Williams
12-28-2018, 1:12 PM
a) what's your approx. focus distance the lens to the work? My 70mm lens focuses as something like 4-3/4" (my 150 is 11-something inches, my 220 is 14-something, for reference)

b) are your F3 parameter settings in the ballpark? Field size entered is directly proportional to output size-- are there any other places in a MOPA settings menu that might be outta whack?

c) is it possible your machine has some weird inch/mm conversion thing going on?

John Lifer
12-28-2018, 7:01 PM
Did you Buy the 70x70 with your machine? Ray fine sent me setup for both my 100x100 and 150x150 lens. Gave me focal length along with settings for each.
You have to change a good bit under parameters. And I've never run anything over an hour. Even cutting grooves in my G17 slide didn't take that long. Thinking back, probably 20 minutes per groove, about a 1/8" x 1 length and 10 to 15 thousandths.

I use settings of 1500 speed, 100 power, 35 freq on my 20 watt. .02 or .03mm hatch at 90 and 270 with cleanup of 135degrees and power there of 100, 75khz and 2000 speed. Sounds like you were creeping too slow for one thing. Make it fly when cutting.