Need help with photo engraving on wood

[Zahid Naqvi]

I am making a commemorative box for the family of a co-worker who passed away a few weeks ago. I need his picture engraved on the Cherry lid. If someone has done this kind of work before and would like to help please let me know, I also need this done before Dec 15, so that I can deliver the completed piece before christmas.
I have already tried the local laser engraving and trophy shops, no one has done any photos before and are charging upwords of $50 plus setup fee. What can I say Arkansas is that kind of a state.

thanks for any help

[mike wallis]

Hello Zahid,
although I havn't done a whole lot of it, in my experience photo engraving on wood has proven difficult. There are a factors that need to be good in order to make the engraving come out acceptable. One of the main factors is the photo needs to be of good detail and good resolution.
Most of the time the subject has to be extracted from the background. Also if the wood is varnished some half tones might apear frosty when engraved because the laser dosn't penetrate down into the wood on those areas. If to much power is used the engraving is likely to appear washed out.
I get the best results engraving the wood before its varnished. This gives the photo the best gradients of tones. The only draw back from this is the smoke that comes off the wood while engraving can leave a residue. This usally comes off with a damp rag. Once cleaned a clear varnish can be applied by spray can/paint gun.
If your still planning to have the box engraved I highly recomend giving the person who does it a sample piece to test before the final box is engraved. This will can save some grief if a setting needs to be changed. Also who ever does it will likely have a 1-2 of hours logged just in the graphic time so you should be prepared to probably pay for this as well along with the engraving time.
Good luck,
Mike

[Rodne Gold]

Mike , hiya
If you use Photgrav, getting VERY acceptable results is a breeze , shouldnt take longer then 5-10 mins to do , even with background removal. Even my "novice" laser operator gets it right with this program.
Engraving wood with no protection is ok for some woods , but light stuff like birch or ash or oak will stain badly.
The contrast or laser burn in wood is actually due to a side effect of lasers that you normally DONT want , and that is a heat affected zone. If the laser works properly in wood , it vaporises it and actually leaves almost NO contrast.
In effect you want the laser to burn and not vaporise the substrate. So to get the better result , you either want to "clump" the burns , so one spot overlaps the other and you do get a heat affected zone (often raising DPI does this) or go slightly out of focus.
Problem is , if you set too high a resolution (we NOT talking dpi here) then you get a mess.
Why is this so ? Well essentially the laser prints one colour so to get gradations one uses 1/2 tones which are actually "cells" of laser spots with spacing etc
Setting the 1/2 tone method to fine and dpi/ppi of the laser high reduces the resolution of these cells and on wood causes a lot of spot overlaps which will "blur"" the image. This is counter intuitive as one would assume MORE resolution and higher dpi will actually produce better results. So if having unacceptable results at those levels , the place to start is going DOWNWARD in dpi , ppi and using a coarser 1/2 tone screen.
If you actually have a look at the photograv image it outputs for engraving , it looks like a dogs breakfast but engraves very well.
That package looks at the power , spot size , material and so forth and works out a bitmap that optimizes all the aformentiond factors.
One can do the same in a graphics package or with your laser driver , but the variability and schlep involved is not worth it.
Some ppl love it , some hate it ,but in our case Photograv has made it real easy.
My advice to Zahid is to find someone using that package to do his job.
$50+ for it seems a fair amount of money , but then again its a one off, "one shot" (you only get one chance) job

[mike wallis]

Thanks for the info Rodney.
I do use Photograv to process for wood but perhaps im doing something wrong. Typically I keep the image resolution around 400-600 DPI and engrave at the matching resolution of the image. In Photograve I load the appropriate materal param and make minor adjustments in interactive mode.
If you would please tell me your basic process when using Photograv or if you see something im doing wrong let me know.
Thanks,
Mike

[Rodne Gold]

Mike , the problem is that DPI is not equal to the "cells" per inch.
Actually what you really need to do is limit the photo to at BEST to 125 pixels per inch of output , so for example you have to work out engraved size and resample the pic to reflect this.
For example if you want a 6" x 6" picture , it should NOT be more than 750 pixels by 750 pixels. Even that is most likely overkill as the amount of "cells" a laser can resolve on wood is most likely NOT more than 75-100 , 1 pixel is represented by one cell. Try much coarser settings, Work at 200 "dpi" or at best 300 dpi...

[Zahid Naqvi]

Perhaps I was not clear when I posted the original thread. Can someone who does this commercially would like to help me by doing the engraving. The box in question has not been made yet I can ship the lid only, which is pretty flat. Or if you know someone in Dallas or Memphis who does this kind of work I can contact them directly if you would be kind enbough to give me a name and a phone number.

thanks

[George M. Perzel]

Hi All;
Mike, go with Rodne's advice. I've done a lot of different photos on various woods- all done with Photograv choosing the Cherry (only wood they have) parameter. I do not tweak the settings in Photograv at all. Image is cleaned up and sized in Photoshop and set to 300 dpi. Key is to make the image the proper size in Photoshop (or other photo program), adjust the brightness/contrast curves if necessary, send i to Photograv as a bmp file and do not resize the Photograv output. here's a few samples, although the detail is much better than it appears in these photos:
George M. Perzel:

[Jackie Outten]

Hi all,

Just to get things back on track, Zahid is looking for someone to engrave the lid of a box he is making. Any takers?

Jackie Outten

[J Porter]

Zahid... I'm in West Helena (120 miles east of LR, 75 miles south of Memphis. I can probably help you.

Email me @ porjoe@hnb.com

~Joe

[Zahid Naqvi]

Thanks Joe, I sent you an email.