Once again, problems

[Hannu Rinne]

Which lens is better - 1,5" or 2" - when engraving a photo on acrylic ? I didn't realize that acrylic (casted) could be so hard material to work with when doing photos on it. Any suggestions for suitable speed/power/dpi/ppi ? Seems that acrylic isn't my best friend :D

Regards,
Hannu

[Mark Sipes]

I use a DPI of 333

[Martin Boekers]

Acrylic is usually a pretty good substrate for photos. Are you
converting to halftones through software or using driver settings?

What do your engraved pieces look like?

I always recommend searching You Tube for this, Roy Brewer has
an excellent video on prepping the image in Corel.

There are many great videos on You Tube for lasers.

There is much right here on SMC if you use the search engine.

[John Noell]

I have seen very little difference due to the lens focal length. However, the PREP process you use on the photo is absolutely critical. And some photos simply won't give good results. Some of the people here (e.g., Frank Corker) are incredibly good at photo prep. The photo Frank prepped for me engraves great with both 1.5" and 2" lenses.

[Hannu Rinne]

Here is the image what I've been playing with. The photo is prepared in PS and then I ran it through Photograv with clear acrylic settings. This last test is made with the settings as; DPI 380 / PPI 350 / Speed 90 / Power 23 and with 2" lens. The size of the work is 7,9" x 11,85". The picture resolution was 400 Dpi. This is my attempt nr. 10/10 - and it was absolutely the last one, I'm tired...:D

Regards,
Hannu

[Scott Shepherd]

I don't know what PPI is on the GCC, but on every other laser I have seen, PPI is for vectoring only. DPI is for rastering, and, as a general rule, the DPI of the photo should match the DPI of your laser. You don't generally want to have a mismatch between the two. Sometimes it seems to work fine, other times, it can introduce really odd patterns you can't get out, patterns that look like laser issues.

Try to make them all the same DPI.

[Gary Hair]

Scott is right about PPI not being used for rastering, it is Pulses Per Inch and is for vector cutting only. It won't matter what you set it to if you are rastering.

Gary

[Dee Gallo]

Hannu,

I'm not sure about what I am looking at - is that puppy just floating by himself on the acrylic and the blurry background is something behind the piece? Also, what do you consider the problem?

From what I see on my screen, it appears that there might not be enough contrast, so the blacks are not as dark as they should be. But I think you got the lighter fur to show very well - we all know that black or white animals are difficult... double that with a light furry animal with a dark head!

~ dee

[Steven Cox]

Not sure what you are doing in PS to work the image but here's a little tip to help define the egdes, not this process works better for clipped images. Like Dee I looked at your image and was unable to determine if the background was part of the image or not, I suspect it is so you might be better off clipping it.:

1. Open the image

2. Duplicate the image Layer, then with the duplicated layer selected in Layer Manager

3. Go to Filters > Other > Hipass

4. Set the Pixel Value to 20 (20 seems to work best) then click ok

5. Back in the Layer Manager change the Dropdown from Normal to Soft Light (depending on the image you could also use Hard Light)

6. If you toggle the layers view icon in the Layer Manager you'll see the difference.

7. Now merge the two layers together.

Forgot to mention those that don't have Photoshop you can do the same in Corel's PhotoPaint. I Hipass all my images for laser engraving.

[walter hofmann]

Hi hannu,
I just wana mention from my experience in regards to the kind of lense. it is importand to have the right working hight for each lense :
1.5 inch lense needs the work piece set at 1,5inch down from the lense, and 2 inch lense needs the work piece set to 2 inch down from the lense.
a 1.5inch lense brings more crisp results especially by picture.
that maybe helps
greetings
walt