Intensity Varying

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Honk
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Intensity Varying

Postby Honk » Mon Apr 13, 2015 6:58 pm

Varying Intensity
I am getting something bad happening! What could this be? Dark and light areas in Horizontal and 45 Degrees? I have tried fast, slow, and quite a few different settings in PEP.
test.jpg
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2015-04-13 15.41.04.jpg
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There are funny little loops at the end of travel and it doesn't seem to change power until the change in direction. I been messing with it all day and it is only getting worse. I think I broke it! any Ideas? This picture of this idem is about 6 inches long and 3/4 inches wide.
Thanks Jerry

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Picengraver
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Re: Intensity Varying

Postby Picengraver » Mon Apr 13, 2015 7:35 pm

Jerry,
Not enough info. What are you trying to engrave? Please post the original image and we can check it for you.

Have you made any changes to Mach3?

John

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Re: Intensity Varying

Postby Picengraver » Mon Apr 13, 2015 8:38 pm

Jerry,
I meant to add that what I see on the pictures could be the wood. What is it?
John

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Re: Intensity Varying

Postby Honk » Mon Apr 13, 2015 11:04 pm

llioncubeveefront.005.jpg
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number1.jpg
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I'll do more later thanks Jerry

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Honk
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Re: Intensity Varying

Postby Honk » Tue Apr 14, 2015 12:10 am

Wood, Poplar. No changes in Mach3. I'll email the G code file if you need it. What happens when a laser diode starts going bad?
Jerry

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Re: Intensity Varying

Postby Picengraver » Tue Apr 14, 2015 5:27 am

Jerry,
I think what you are seeing is not laser diode failure. It is most likely the natural variations of the wood itself, plus a slower feed rate causing some over-burning, and perhaps an excessively enlarged image(?).

The image itself is near all mid-gray shades, with un-sharp details, so there is not much spread in gray shade values that would normally help mask the naturally variable burn characteristics of the wood grain. Am I correct that the original image much smaller, and then enlarged quite a bit for engraving?

Can you post a picture of the complete engraving? It will help to see if I am correct about the wood grain causing your "zebra" issue.

You might try sharpening the image some before generating the gcode, and also use a larger pixel resolution (0.005" is usually too low for a laser diode), and use a higher feed rate. I am doubtful, however, that this image is going to give you satisfactory results.

Hope this is helpful.
John

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Honk
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Re: Intensity Varying

Postby Honk » Tue Apr 14, 2015 8:32 am

lyon cub round .JPG
lyon cub round .JPG (337.5 KiB) Viewed 10597 times
John
This Picture is right out of the camera, I did touch up the snow flakes and crop it some, if anything shrank the picture. The original is 2.78 MB. I have it in three heights as it is already spindle engraved and that came out real good. The dimensions of the hole picture are 24 X 24 inches. I did question the wood grain issue at first but when it followed the 45 degree burn that didn't make since. I will speed it up and try it again, I'll let you know
Thanks again
Jerry ps. Oh yah I know it's not a cub its a kitten.

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Re: Intensity Varying

Postby Picengravertoo » Tue Apr 14, 2015 8:49 am

Honk wrote: What happens when a laser diode starts going bad? Jerry


You have to run a very low feedrate because it's loosing it's burning power. Are you using the full 0-5v range from the encoder to the modulation on the driver with the -.0255 depth setting? 48IPM with a 25% Feed Rate Change seems pretty darn slow to me. Maybe it's time to replace your lens. After a period of time, it may get cloudy and you lose the burning power and detail.

Jeff

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Re: Intensity Varying

Postby Picengravertoo » Tue Apr 14, 2015 3:53 pm

Jerry,

I downloaded your kitten and re-sized it for the piece of Poplar I have and adjusted gamma to .8 and and sharpened it to 20. In PEP5, I used a 105IPM feedrate and a FRC of 25% with a Pixel Resolution of .006" and engraved it at 45D Right. Since it was done on our Shapeoko and the 2.8W J-Tech laser, I used a Min 10 and Max of 255 S power command. I did this to show that sharpening will bring out more detail and that you should be able to engrave faster then you are.

Jeff

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Honk
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Re: Intensity Varying

Postby Honk » Tue Apr 14, 2015 4:52 pm

Thank you Jeff
That's great!!
I think there is another problem that needs attention first. I tried that multi shaded test thing you all made and It has the same problem I was at 110 i.p.m. 25 % .005 resolution. The Zebra effect (for lack of a better term) is also present and it has nothing to do with the grain of the wood. I tried it 45D grain right, left, vertical horizontal etc. The effect is always in the same place and the same direction. I have a feeling that one of the bearings on the Y axis is crabbing the rail. Misalignment??? I'm not sure but if I try to adjust the bearings on that rail I can increase the size and spacing of the Zebras' stripe. If I get it to loose it just wonders all around. I have been wanting to improve the system with some rails and lineal axis bearings. I am thinking that I will try that next but I need to save up first, them things are pricy. I should have left things alone and just done horizontal, this started when I put the y axis on that diet. (I think).
Thanks Jerry


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