How to mill a word in wood? please help

[casperove]

Hello,

I am abit new toCNC and I was inteested to try the Meshcam. I am using the Sherline CNC milling machine, and I installed the trial version of Meshcam to try it out. It looks an interesting application. What I didnt know about the software is how to decide the Zero level of Z-axis. as I generated the G-code and I run it using Mach3, I realised that the Z-axis always go above the wood board I am tring on. I tried a very simple project, I wrote a word on Autocad, saved it as DXF, imported it into Meshcam and generated the G-Code. Any one can help on how to draw or write that word on the wood? I want the word to be -1.0 mm above the wood surface. I need to dig the word in the wood not to mill the whole wood and keep the word up.
Any help would be highly appreciated.

[Randy]

Hi casperove, and welcome to the forum. Make sure you set the Program Zero (under the CAM menu) to the top of your workpiece. I usually use the top front left corner. That way all the machining Z coordinates will be negative. That is assuming that you touch down your tool to the top of the stock and zero your machine's Z coordinate too.

That is the most convenient thing to do, but I have also touched down the mill's Z to the bottom of the workpiece (i.e. the table or parallel the rawstock was setting on) and also set MeshCAM's Program Zero to match. The key is having the same Z zero reference in the program and on your machine.

Randy

[cnczane]

...and I always define Z=0 at Top, Middle and always make sure I fib "just a little" about the model's XY dimensions when importing it, telling MC it's just a wee bit larger (like 0.05") than my blank.

I've discovered that "stock" lumber isn't and that using the center and cutting just a little oversize (sort've) (often) guarantees decent results with "nearly right" sized blanks.

Also, I don't bother defining the model dimensions, just letting them default to those of the digital model that was input. If I have a bw image to input, "black" (assuming I choose "black is deeper") will be at the Z dimension I told MC when I input it--and note that it can be anything I want--and white will be the top.

Imagine I have an image of 50% gray letters on a black (100% gray) background surrounded by a white border. If I import the image to MC and say that it's 3/8" tall, the deepest cut (to black) will be 3/8" deep and the letters will be 3/16" tall. If 1/2", make those numbers 1/2" and 1/4" respectively. (So that you don't have abrupt up- and down-cuts at the black-white borders, bring the image into GIMP first and blur that region first. Do the same with gray-black too, but less strongly.)

I just ran across an Etsy store that does beautiful multi-layer signs for family names, and stains the letters on each layer differently. Quite striking.
https://www.etsy.com/shop/Lovejoystore? ... -info-name

LovejoyStoreSign.jpg (19.44 KiB) Viewed 6393 times

Gimpchat.com has a tutorial for adding a picture frame to a photo: the same technique can be used in GIMP to add an undulating grayscale frame border to the image before being brought into MeshCAM. (User ofnuts created the sine qua non script; user mahvin wrote the tutorial.)
http://gimpchat.com/viewtopic.php?f=23&t=1119
--
David
P.S. I have no affiliation with lovejoystore in Minnesota.
I am not Dan & Kathy BRADY either.

[JJKIZAK]

...and I always define Z=0 at Top, Middle and always make sure I fib "just a little" about the model's XY dimensions when importing it, telling MC it's just a wee bit larger (like 0.05") than my blank.

I've discovered that "stock" lumber isn't and that using the center and cutting just a little oversize (sort've) (often) guarantees decent results with "nearly right" sized blanks.

Also, I don't bother defining the model dimensions, just letting them default to those of the digital model that was input. If I have a bw image to input, "black" (assuming I choose "black is deeper") will be at the Z dimension I told MC when I input it--and note that it can be anything I want--and white will be the top.

Imagine I have an image of 50% gray letters on a black (100% gray) background surrounded by a white border. If I import the image to MC and say that it's 3/8" tall, the deepest cut (to black) will be 3/8" deep and the letters will be 3/16" tall. If 1/2", make those numbers 1/2" and 1/4" respectively. (So that you don't have abrupt up- and down-cuts at the black-white borders, bring the image into GIMP first and blur that region first. Do the same with gray-black too, but less strongly.)

I just ran across an Etsy store that does beautiful multi-layer signs for family names, and stains the letters on each layer differently. Quite striking.
https://www.etsy.com/shop/Lovejoystore? ... -info-name

LovejoyStoreSign.jpg

Gimpchat.com has a tutorial for adding a picture frame to a photo: the same technique can be used in GIMP to add an undulating grayscale frame border to the image before being brought into MeshCAM. (User ofnuts created the sine qua non script; user mahvin wrote the tutorial.)
http://gimpchat.com/viewtopic.php?f=23&t=1119
--
David
P.S. I have no affiliation with lovejoystore in Minnesota.
I am not Dan & Kathy BRADY either.

When you say "black is deeper" do you mean that the "Z" is set to "-Z"?
JJK

[Randy]

Hi JJK and welcome to the forum. Yes, you are right. When you import a bitmap, black can represent either height or depth so for "black is deeper" you select the Z- option.

blackdeeper.png (19.02 KiB) Viewed 5962 times

Randy

[cnczane]

(Thanks, Randy. We were out-of-pocket for a few days.)

"Black is Z-"

means that Black(er) shades represent the "negative-Z" direction, and conversely, White(r) shades are in the "postive-Z" direction.

Going from darker-to-lighter shade is "up." From lighter-to-darker, "down."

"Black is Z+"

is the exactical opposite.