Gray Scale cut depths

Thought this might help when designing in gray scale. These are the doc in Easel with these percentages of gray. Doesn’t seem to follow or have any pattern to the doc versus amount of gray, but it is what it is I guess. Might help with getting close when you import svg.

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This will change depending on the material thickness upon import. If material thickness is set to 1" then a 50% grey will be a doc of .5" but after import if the thickness changes, the doc will stay .5" and not scale.

Yep, your right. It does change dependent on material thickness. I ran my test with .5" material, but I only got .424" when I imported to 1" material @ 50%. Where do you think the discrepancy comes from?

Depends on how you are creating your SVG

Can you step me through what you do to create a grey scale based SVG and maybe post an example?

That’ll help me see if there are any tweaks that you can make to be more accurate.

I create my artwork using CorelDraw which has a 256 shades of gray palette I can use.
I export/ save as .svg directly from Corel. This piece of the big isl of Hawaii was done with 16 shades of gray. I just experimented with gray levels until it matched the topo elevations and looked right. Didn’t matter too much in this case to get each level to cut as an exact known doc, but would be nice to export .svg files and not have to change each level of gray scale to get the doc you want.

Hi @JeffParish

Sorry I didn’t get back to you about this right away… I didn’t forget.

Nice carve by the way. You might be a shoe-in for a future Tip-Jar (hint hint… keep one of these up your sleeve)

Would you mind posting an example SVG of something you expect to be one depth but shifts slightly?

Here’s a file in Easel. Circle is in 20% increments and bar is 10% to 100% gray scale.
Maybe you can shed some light on the difference of doc expected.
http://easel.inventables.com/projects/gNFNM3V4SHKsjfzAHjeSFA

Ok, thanks! I’ll take a look at it tonight and see if I can notice anything that might be doing this.

Edit: I’ll need the SVG file to see the discrepancy. Can you post it here?

It won’t let me send a .svg file. Only images. PM me your email and I can send unless you know of a way I can attach file here.

You can use the “upload” button, and select the file to upload, on your post

Tried that. Still only uploads a image of the file and not the actual file.

Are you sure ? I was able to do it in this thread Need help with efficient milling and svg . You can just right click the image I uploaded to download it. It does change the filename though.

Images yes, but I’m trying to send the actual .svg file. Won’t do it.

If you use the upload button and wait for it to finish uploading it will place code into your post. Then when you click reply it will look like it is just an embedded image, but that image will be an SVG file that others can drag and drop onto their desktop.

Like I said, I uploaded an svg in that other thread. It may be that the file filter for the upload is not set to show all files, in which case set it to all, but there doesn’t seem to be any restricting in uploading svg’s

Ok, I think I see the problem in the SVG that you sent.

I think that even though the SVG is saving in RGB color you may be working in a CMYK color space when creating the image.

Here is a screenshot of the colors as I see them when opening the file:

You can see that the HSB aren’t quite grey, but rather a mixture of colors. You can also tell this by the HEX value at the bottom. If it was to be black (full depth cut) then the HEX will be 000000, or if it was a deep cut then it would be 212121 (reading at 13%) the hex value will be 3 of the same number if it is really a grey scale value. The image below is what you would want it to be for 13%

In Illustrator there is a way to set a bunch of vectors as grey scale, but I wouldn’t know how to do this in a sweeping scale to a bunch of vectors in Corel Draw. There is another thing in Illustrator that I check for and that is the document color space… making sure it is RGB. If there is a way to set this in CD then you will want to check that it has been set.

So going forward, if you have a specific percent depth that you want to achieve like say 25% then make sure the HSB is set to H: 0%, S: 0%; B: 75% and your HEX value will read #bfbfbf

Hope that helps troubleshoot the issue.

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I see what your saying. Did not know saving gray scale vector images as .svg saved them in rgb format. Never check that out. That messes everything up when your working with pure blacks (k) and now you have percents of rgb. I’ll see if I can get a work around in Corel. Thanks Jeremy. You are a smart guy!

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Just a side note here:

pure K as in CMYK black is not actually really pure black. Something closer to real black is what is called “rich black” and is a mixture of all CMYK together… This is all because we are talking about an additive process where inks are added to make colors.

For the purposes of this project you’ll want to work from end to end in RGB where real black is achievable and is the subtraction of every color hence #000000

Yes , I knew that. Even have a rich black selection on my pallett. Used it for special cmyk printing jobs.

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Just created a RGB gray scale color palette for drawings that are save as .svg and imported into Easel. As long as your material thickness is set before importing .svg, all your doc’s are 100% accurate. Very cool! Now what I see is what I get. Thanks for all your imput. Got me understanding the doc problems with gray scale and now have a fix!

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