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Thread: Need help with understanding what I am doing wrong. Laser alignment

  1. #1

    Need help with understanding what I am doing wrong. Laser alignment

    My wife and I purchased a used laser in 2016. It's a mini 30 watt 24". It came with the rotary attachment and it was a very well maintained machine. We use it only for wine glass etching and we have always not had the best luck finding the sweet spot. I tried everything, from power adjustment,focus, changing the settings ( speed, power, and design color etc 80% black ) It worked out ok for two years and I always chalked it up to the fact that most likely the laser tube needed to be reconditioned. Last year we found an amazing deal on an Epilog Mini 50 watt with rotary attachment and decided to pick it up. This thing etches so much better than the 30 watt. The etching looks flawless and even a little out of focus ( on the curve of the glass ) it does such an amazing job compared to the 30 watt.

    I figured might as well replace the 30 watt tube to get it running like the 50 watt. We got the tube replaced last week, showing about 35.5 watts of power at peak. I was so excited to get it in and running ( expecting it to be like the 50 watt ). I ran the first job, and....ehhh. The etching looked ok. I have tried everything- adjusting power levels, speed. It looks much better than it did before we replaced the laser tube but it's no where compared to the 50 watt etching. The laser beam is aligned and the mirrors and the lens are cleaned. When we etch, we have always used some sort of a mask , usually a face wipe, and we have had extremely good success with the 50 watt. But when lasering on the 30 watt, the etching looks just ok. Our main problem is the edges of the design. We will always get little rough spots and you can see where the glass just didn't etch well. The glass we use is not very round. I have even tried etching in the middle of the glass with a small design where it is extremely flat. I know glass is somewhat tricky to etch, but the fact that our 50 watt does such a better job than our 30, makes me wonder if I am missing an important factor is trying to figure this out.

    Any help would be much appreciated as I have ran out of options.

    Thanks guys!

    Mike

  2. #2
    Join Date
    Dec 2010
    Location
    NW Arkansas
    Posts
    1,415
    Have you tried to post your question to the epilog Facebook group? There are a number of folks doing a wide variety of glass there. But it is a distinct issue with some users. I do a decent number of liquor bottles for a distributor here. I mask with a paper mask for vinyl installation. It definitely helps on glasses, and on the bottles. The square bottles I mainly do etch really well with decent size graphics. Thin letters, fine details, not as good. wide bold, great. I hit with about 50% of my 80watts (which is about 20mA or so). My guess is that you aren't hitting with enough power as compared to the 50 watt machine.
    Woodworking, Old Tools and Shooting
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  3. #3
    It's likely not so much the laser or power as it is the way the machine is processing the image.
    My 2 Gravographs have a fully automatic photo mode, that make things real easy-- usually...
    My GCC Explorer has a multitude of photo options, but I've yet to find one that will engrave glass decent.

    What DOES work with the GCC- and my Gravograph's too, is this procedure, assuming you're using Corel:

    make your graphic/text/etc., ready to engrave
    paint it 80% black (to start)
    group it and copy it
    open Corel PhotoPaint, and paste 'new from clipboard'
    when the 'convert to bitmap' box comes up, resize to 400%-
    You'll likely have a checkered 'invisible' background- click on OBJECT/COMBINE/Combine all objects with background...
    now click on IMAGE/Convert to black/white -- then chose STUCKI as the conversion method, slider at 100%.
    You'll now have a nicely dithered image-- copy and paste it back into corel
    Group it and resize to 25%, this brings it back to actual size
    Now, engrave it as a typical black anything else, no 'photo mode' help of any kind-
    Try 400x400 dpi resolution, and with 35 watts try 85% power and 30% speed...

    Using the Stucki dither at 400% up-size works great for me, and I prefer Stucki because the edges always seem cleaner.

    This example 'ABC Co.' is CloisterOpenFace made to 2" long, height works out to just under 1/2"-
    top is black, 2nd down was returned from 80% black, bottom was 70% black, and a closeup of the B's at 80% and 70%...
    (and the photo reproduction isn't too great)
    dither.jpg


    dither2.jpg

    --the whole trick is to break up the firing of the laser, which really helps reduce the over-fracturing and shards that end up looking like un-engraved spots. You may find 70% works better, or even 60%, experiment!

    This is a screenshot of the image I'm engraving on these wine glasses below
    (the dither is almost gone in the photo, pics don't transition well to the website)
    btg1.jpg
    btg2.jpgbtg3.jpg
    -again, the photo doesn't show the dither well, but the glasses don't lie! One on the left was done on my LS100, on the right was done on the LS900, 2 different machines, same basic results. And for what it's worth, I've never applied anything to the glass, just dry glass and laser light

    Using 'my own' dithering has been working out well for leather too...


    .
    Last edited by Kev Williams; 11-08-2018 at 11:06 PM.


  4. #4
    Join Date
    Jan 2008
    Location
    Rock Hill, SC
    Posts
    108
    I've been doing glass for some time but it was never as good as I would have liked it. I am going to try your method Kev. Thanks again for a great tip!!
    Universal 60w VLS6.60 w/ rotary
    RayFine 30w MOPA
    Corel X8, Photoshop

    Fab shop with South Bend Heavy 10, Bridgeport 9x42, 185a welder and a multitude of supporting tools/equipment

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