cutting out a border via art import?

General MeshCAM Art Questions

cutting out a border via art import?

Postby Josh » Mon Nov 26, 2012 10:48 pm

Hello,
I am just digging into MeshCAM and so far its pretty straight forward to use.. I am trying to make a simple sign for my "workshop" (by that I mean the garage because I am just a Hobbyist)... For now I am making an image to import (because I am still exploring CAD options but I am not to bad at Illustrator and Photoshop) but I am having the darnest time trying to express cutting a border ( I am looking at about 3" radius corners on my 10" wide sign that I'll be cutting out of 12" stock...

I don't want to machine away all the "excess" material, I just want to plung thru the stock around the outside.. I was thinking maybe I need to make two gcode files (one for the border, one for the rest of the art) and run them seporate.. But before I did that I figured I would ask..

Also (according to CutViewer) I am getting a lot of collisions when the system trys to do the detail work with 1/8" bit.. I though MeshCam was suppose to detect those kinds of things and just not cut them.. Or is CutViewer not interpreting the path and Tool correctly?

Thanks
Josh
Very much a Newbie
Josh
 
Posts: 5
Joined: Mon Nov 26, 2012 10:18 pm

Re: cutting out a border via art import?

Postby Randy » Tue Nov 27, 2012 6:31 am

Hi Josh and welcome to the forum. Don't worry--we all start(ed) as newbies.

Generally yes, if you want to cut just the face of the sign and then go back and cut the outline, that will need to be two steps. I will need to admit that my knowledge of the Art side of MeshCAM isn't what it probably should be, but in the general sense (machining an imported STL file) there are two main tools to use to restrict machining. A Machine Region lets you set a boundary that confines MeshCAM to machining on a specific area or areas of your workpiece, and a Check Surface is a separate STL that you superimpose on your workpiece to act as a mask, and MeshCAM will only process the areas of the workpiece outside the Check Surface. What I don't know is if you can use those two items in Art. I think so, because MC makes an STL that you define by the Art commands, but I'll need to do some playing to find out for sure.

About the collisions--CutViewer collisions are usually rapid moves below the top surface of the stock, at least in my experience.

Could you post a couple of screenshots showing first what specifically you are trying to do and second, what CutViewer shows the collisions to be?

Randy
All opinions in this post are mine alone. I am not a MeshCAM employee, I do not have a financial interest in MeshCAM, nor do I speak for MeshCAM. MeshCAM user since Beta 5 in 2003. viewtopic.php?f=11&t=15333 :ugeek:
Randy
 
Posts: 1812
Joined: Wed May 14, 2008 9:50 am
Location: North Texas, USA

Re: cutting out a border via art import?

Postby Josh » Tue Nov 27, 2012 10:48 pm

I ended up having to do as you mentioned and make two files... lining up the two seporate jobs is kinda rought for a first time project but I figured it out.. By the way Adobe no longer exports DFX R12... So I had to figure out a whole new process... For postarity sake here it is (for others)..

1) Download and install Inkscape
2) Download and install the better DFX export for Inkscape http://bobcookdev.com/inkscape/inkscape-dxf.html (the current ones in inkscape won't open in MeshCAM either)
2) Save your drawing in Adobe as a SVG
3) open the SVG in Inkscape and save it as a DFX
4) open the DFX in MeshCAM
5) Choose MMs (thats what the size will look like but its not, just use it to avoid rounding erros in the next step) and set the thickness of your model
6) open Define Stock to get the exact size MeshCam thinks it is (click your target units.. for me thats inches)
7) select all of your items in Illustrator and open the info pane/Window...
8) do some basic math to figure out the scalling factor (MeshCAM width/Adobe Width)
9) Scale your model in MeshCAM but not uniform (don't want to mess with thickness) so place your scaling factor in the X and Y boxes...
10) [BUG ALERT!] when you save your G-Code it will still use MMs for the size of your stock.. For mean that ment all the X/Y/Z movements were in Inches but the stock size was completely wrong (in MM) making CutViewer very confused (my cuts were this tiny dot in the corner)... open a text editor and fix the stock size to what ever it sould be...

As for the error I was getting when I tried to do everything in a single image
"Cut depth is greater then cut length of tool" was what I was getting... It was throwing the error when trying to cut out the black areas around the edge.. (the idea was that Black was cut thru, Red was the top of the stock and all the verious colors would be lower then red to carve out the design. the STL looked like the second attachment..

I think one "quick" improvement to MeshCAM Art would be to provide a "thru model" color.. so if you say black is cut thru the stock then you can place supports around it or something like that.. as it is you have to set black to zero which is "kind of" thru the stock but not really. (just my two cents).

oh and while I have a process to import DFX's from Illustrator, that area of the code probably needs a little love and attention.. Sorry, I bet file format support isn't pleasent.

But the tool really is very impressive.. I can't wait to lock down my piece of wood and cut this sucker out..

Josh



Oh,
Attachments
Untitled.png
Untitled.png (313.85 KiB) Viewed 4088 times
board.png
board.png (69.93 KiB) Viewed 4088 times
Josh
 
Posts: 5
Joined: Mon Nov 26, 2012 10:18 pm

Re: cutting out a border via art import?

Postby Randy » Thu Nov 29, 2012 7:02 am

Josh, thank you very much for the pictures and description. About the "Cut depth is greater then cut length of tool", MeshCAM doesn't keep track of the flute length, but does keep track of a cutter with a larger shank so that the shank doesn't hit the workpiece. For the time being, it's up to you to choose a cutter with long enough flutes. But if it was me, I'd be using a larger cutter for the perimeter anyway. I'd also probably keep the radial supports about half the thickness of the workpiece so that the hand-finishing to cut and smooth them wasn't near the "front" of the sign. And there is no harm in lying to MeshCAM about the thickness of the workpiece--make it .010" thicker than your stock and flush on the top, and "bottom of the stock" will become ".010" below the stock". (For that matter, you will likely get used to lying to MeshCAM about various things, mostly stock dimensions--MeshCAM only knows what you tell it, and that is something you can exploit...)

But I don't understand your whole SVG > DXF > MeshCAM process. Aren't you using board.png as the input for Art? I'm feeling like the newbie now, because I've only used bitmaps as input on the Art side of MeshCAM (on the few occasions I've worked with that side)

Randy
All opinions in this post are mine alone. I am not a MeshCAM employee, I do not have a financial interest in MeshCAM, nor do I speak for MeshCAM. MeshCAM user since Beta 5 in 2003. viewtopic.php?f=11&t=15333 :ugeek:
Randy
 
Posts: 1812
Joined: Wed May 14, 2008 9:50 am
Location: North Texas, USA

Re: cutting out a border via art import?

Postby Josh » Thu Nov 29, 2012 4:49 pm

I uploaded the files I used that were failing... I changed my approach after the first conversation and made two separate STLs the first was just a DFX of the perimeter.. I used that instead of the black hatch's to cut out the sign from the stock.. I then used a PNG (same as the one below but without the black border) .. So the narely multi step process was to export the DFX parimeter and make sure that it would generate gcode that would exactly line up with the PNG sign...

it worked, but as a "first time project" it was a bit stressful.

I thought the video said that the length of the shank was ignored but the length of the flute was tracked by MeshCAM? I'm going to have to re-watch the tool input video again.

Josh
Josh
 
Posts: 5
Joined: Mon Nov 26, 2012 10:18 pm

Re: cutting out a border via art import?

Postby Randy » Thu Nov 29, 2012 6:36 pm

Josh wrote:So the narely multi step process was to export the DFX parimeter and make sure that it would generate gcode that would exactly line up with the PNG sign...

OK, Josh. I was wondering why you didn't just use a second copy of the PNG with only the border and supports.
Josh wrote:I thought the video said that the length of the shank was ignored but the length of the flute was tracked by MeshCAM?

MeshCAM does track the length of the cutter to where it flares out for the shank, but only to avoid shank crashing. I think that MeshCAM only uses the flute length in relation to the stepdowns you have specified--but not the total depth from the top of the stock. I have several 1/8" cutters with 1/8" shanks but with different flute lengths.
long-reach.jpg
long-reach.jpg (27.42 KiB) Viewed 4077 times
To MeshCAM they are all the same, because I never program a stepdown longer than the flute length. But I do poke a long cutter with short flutes way down in the workpiece on occasion. Generally for me the flute length isn't the issue--it's how much of the cutter is protruding from the collet so that the collet doesn't hit the workpiece on deeper areas.

I just watched Robert's tool video and it isn't extremely clear on the flute length issue--and Robert doesn't go in and actually enter a flute length and shaft/shank diameter and show what happens. For that matter, in my experience MC assumes that the cutter suddenly widens to the shaft diameter right at the back of the flutes, without a tapered section. But again, I stopped worrying about that years ago and just choose my cutters based on what I know I'll need to use.

Randy
All opinions in this post are mine alone. I am not a MeshCAM employee, I do not have a financial interest in MeshCAM, nor do I speak for MeshCAM. MeshCAM user since Beta 5 in 2003. viewtopic.php?f=11&t=15333 :ugeek:
Randy
 
Posts: 1812
Joined: Wed May 14, 2008 9:50 am
Location: North Texas, USA

Re: cutting out a border via art import?

Postby Josh » Thu Nov 29, 2012 7:12 pm

There is a bit of Illustrator Voodoo going on there, the black outline is actually a much thicker stroke just hidden behind the brown.. I could have done two PNGs but then I would have had to re-work the black line.. and try to make its outside exactly match the outer edge of the brown... Doable but then I wouldn't have gotten to test the DFX import or the adding supports to the model... So ya two PNGs might have been easier, but a DFX with the support spurs matched up to a PNG gave me an opportunity to learn more about the tool...

Robert, if your listening.. letting us pick a "all the way thru" color in MeshCAM Art so that we could then later attach spurs would be AWESOME! Just a little FYI :-P

Thanks all... I'll be sure to post the final cut piece when I am done machining it.
Josh
 
Posts: 5
Joined: Mon Nov 26, 2012 10:18 pm

Re: cutting out a border via art import?

Postby Randy » Thu Nov 29, 2012 8:03 pm

OK, fair enough. I've never used DXF as an input to MeshCAM (I use DXF's with a 2.5D CAM program I also use extensively) so I can appreciate your tutorial on matching a DXF outline with a PNG image.

But PNG is just a bitmap format. What I'm wondering is why you wouldn't just copy board.png and edit all the interanal content out in, say, IrfanView, make boardoutline.png and define its black depth to be .010" deeper than your stock? Still flush on top, or for safety raise the "top" to be .010" higher than your stock so there isn't any chance of touching an already-machined surface? Without going back to Illustrator? The two images are guaranteed to line up then...
boardoutline.png
boardoutline.png (42.48 KiB) Viewed 4077 times

Randy
All opinions in this post are mine alone. I am not a MeshCAM employee, I do not have a financial interest in MeshCAM, nor do I speak for MeshCAM. MeshCAM user since Beta 5 in 2003. viewtopic.php?f=11&t=15333 :ugeek:
Randy
 
Posts: 1812
Joined: Wed May 14, 2008 9:50 am
Location: North Texas, USA

Re: cutting out a border via art import?

Postby AdPrinter » Thu Nov 29, 2012 10:29 pm

Josh wrote:I ended up having to do as you mentioned and make two files... lining up the two seporate jobs is kinda rought for a first time project but I figured it out.. By the way Adobe no longer exports DFX R12... So I had to figure out a whole new process... For postarity sake here it is (for others)..

1) Download and install Inkscape
2) Download and install the better DFX export for Inkscape http://bobcookdev.com/inkscape/inkscape-dxf.html (the current ones in inkscape won't open in MeshCAM either)
2) Save your drawing in Adobe as a SVG
3) open the SVG in Inkscape and save it as a DFX
4) open the DFX in MeshCAM
5) Choose MMs (thats what the size will look like but its not, just use it to avoid rounding erros in the next step) and set the thickness of your model
6) open Define Stock to get the exact size MeshCam thinks it is (click your target units.. for me thats inches)
7) select all of your items in Illustrator and open the info pane/Window...
8) do some basic math to figure out the scalling factor (MeshCAM width/Adobe Width)
9) Scale your model in MeshCAM but not uniform (don't want to mess with thickness) so place your scaling factor in the X and Y boxes...
10) [BUG ALERT!] when you save your G-Code it will still use MMs for the size of your stock.. For mean that ment all the X/Y/Z movements were in Inches but the stock size was completely wrong (in MM) making CutViewer very confused (my cuts were this tiny dot in the corner)... open a text editor and fix the stock size to what ever it sould be...

As for the error I was getting when I tried to do everything in a single image
"Cut depth is greater then cut length of tool" was what I was getting... It was throwing the error when trying to cut out the black areas around the edge.. (the idea was that Black was cut thru, Red was the top of the stock and all the verious colors would be lower then red to carve out the design. the STL looked like the second attachment..

I think one "quick" improvement to MeshCAM Art would be to provide a "thru model" color.. so if you say black is cut thru the stock then you can place supports around it or something like that.. as it is you have to set black to zero which is "kind of" thru the stock but not really. (just my two cents).

oh and while I have a process to import DFX's from Illustrator, that area of the code probably needs a little love and attention.. Sorry, I bet file format support isn't pleasent.

But the tool really is very impressive.. I can't wait to lock down my piece of wood and cut this sucker out..

Josh



Oh,

What I have typically done, to avoid the problems created with support "tabs" around the piece, is to set the depth of cut to be just shy of cutting completely thru the stock. Then, once all carving has been completed, I remove the piece from the table, flip it over, re-mount it to the table, and just cut a pocket which is slightly larger than the perimeter of the carved piece. (Basically, just use the Router as a planing mill). It is important to mention here, that the tool path creation for the pocket cut should be done from the inside-out. This will insure that the back side of your piece is planed to a uniform thickness, as when the tool path reaches the outer perimeter of the carved (front side) of the piece, it will drop from the stock onto the table. You may find, that the use of alignment pins on your table will accomplish many things: speeds set up time, since your stock always begins in the same place each time, also allows for precisely locating the "flip side" of stock (for the above described "planing" operations). These alignment "pins" may be permanently mounted to your table, or removed when needed. The trick to using this type of system, is to make a template out of a piece of plywood, or sheet metal for locating the registration holes acurately. Use this template to drill your stock with thru holes each time, then it becomes a simple matter of dropping the stock onto your table, aligning the holes with the pins, until it "drops" into place - ready to apply your hold-down clamps. Also allows for 2-sided machining of pieces, since the flip side will be perfectly aligned with the first side machined.
AdPrinter
 
Posts: 56
Joined: Sun Oct 04, 2009 6:18 am

Re: cutting out a border via art import?

Postby Randy » Fri Nov 30, 2012 1:08 am

I have been sloppy in my speaking here. MeshCAM does keep track of the flute length as it is defined in MeshCAM--the flutes are the whole length of the cutter up to the (possibly) enlarged shaft. My talking about flute length vs. cutter length is entirely my own thinking and doens't reflect how MeshCAM operates. I never tell MeshCAM that any of my cutters have enlarged shafts simply because I do choose the appropriate cutter of the given diameter to use at the time.

Randy
All opinions in this post are mine alone. I am not a MeshCAM employee, I do not have a financial interest in MeshCAM, nor do I speak for MeshCAM. MeshCAM user since Beta 5 in 2003. viewtopic.php?f=11&t=15333 :ugeek:
Randy
 
Posts: 1812
Joined: Wed May 14, 2008 9:50 am
Location: North Texas, USA

Next

Return to General

cron