Newbie trying to drill holes

General MeshCAM Art Questions

Newbie trying to drill holes

Postby marff3 » Tue Apr 21, 2015 10:35 pm

Hello all,

A little background info...

Im new to the CAD and CNC world and just started messing around with MeshCam today. A professor at school built a CNC machine with some students last semester and is encouraging other students to use it. I'm studying printmaking and am trying to use the CNC machine to generate some plates to ink up and print. I think it would be cool to use the CNC machine as a way to generate art. I started by recording the sound of the CNC machine working and then imported the audio files into Pro Tools to generate visual wav images. I then took those wav images and drew points over the peaks in Adobe illustrator.

So now what Im trying to do...

I want to use the CNC machine to drill holes into a plate (in this case, some plexiglass) directly where the points are that I created in Illustrator. While Illustrator may not be the best software to use, I was able to export a .dxf file. However, when I attempted to import it into MeshCam, I get the "DXF File contained no closed contours...." dialog. I understand MeshCam not being able to recognize the .dxf file, but Im confused on how I can go about achieving my goal.

I basically want to use the CNC machine to drill holes about 0.1" deep at fixed X and Y coordinates. Can anyone give any advice on how to generate a correct .dxf file or another way to get the gcode?

Here is a link to one of the images. Its really not complicated at all and I feel like Im not giving MeshCam what it needs.

http://postimg.org/image/btiypfd5b/

Any help or guidance would be greatly appreciated.

- Matt
marff3
 
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Re: Newbie trying to drill holes

Postby Randy » Wed Apr 22, 2015 4:32 am

Hi Matt, and welcome to the forum. MeshCAM treats bitmap input differently than STL input, and cannot do hole recognition on bitmap inputs.

I tried running your JPEG through WinTopo ( http://wintopo.com/wintopo-free.htm ) for edge detection, but that did not work.

This will work, but might not be exactly what you want:

I input your JPEG into Gimp ( http://www.gimp.org/ ) and altered the grayscale curve to make the hole edges as sharp as possible (basically maximizing the contrast):
dotscurves.png
dotscurves.png (27.46 KiB) Viewed 2350 times


I then imported the new JPEG into MeshCAM and scaled to 10 inches wide and .100 inches deep
dots-import.png
dots-import.png (11.61 KiB) Viewed 2350 times


I set the toopath parameters for the typical waterline+pencil finishing for a 2.5D job
dots-parameters.png
dots-parameters.png (87.35 KiB) Viewed 2350 times


and MeshCAM generated toopaths
dots-toolpath.PNG
dots-toolpath.PNG (156.39 KiB) Viewed 2350 times


which look not too unreasonable in CutViewer
dots-cutviewer.PNG
dots-cutviewer.PNG (26.86 KiB) Viewed 2350 times


I'll admit this is nothing like the simplicity of drilling a few holes. It involves a fair time in milling out the recesses but given a bitmap input I think this is the best I could do. And it does involve cutting the stock to the finished dimensions independently from MeshCAM.

For B/W (all-or-nothing) bitmaps it is best to start with a lossless-compression format such as PNG, TIF or BMP. That would eliminate the need to increase the contrast (which I just did to kind of bypass JPG's compression artifacts at the B/W interface).

I think the reason MeshCAM didn't find any closed contours in the DXF is becuase there was no outline to the shape--just the holes themselves. At least that is the same error message I got when I tried importing the WinTopo DXF.

There are mutiple ways to achieve an end goal with MeshCAM, it is just finding out the workflow to do it! I'm not familiar with Illustrator myself so I don't know what all the output options would be. But I am sure that there is a way to ultimately do what you want.

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
 
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Re: Newbie trying to drill holes

Postby AdPrinter » Sun May 24, 2015 8:23 am

Not trying to discredit Randy's suggestion, or advice. But for something as simple as drilling holes at fixed locations, you could always just write the g code yourself, using a text editor like Notepad. A few assumptions are made, here in the following:
1-Stock has already been clamped on the work table
2-The coordinates of the lower-left corner of the stock has been established as X0 Y0
3-The top surface of the stock has been established as Z0
4-The desired coordinates for each hole to be drilled is known
EXAMPLE COORDINATES X1Y1, X1.5Y1, X1.75Y1, X2Y1
Z.1
M3 (Starts the router running, assuming you have the router power under relay control)
X1 Y1
Z-.1
Z.1
X1.5 Y1
Z-.1
Z.1
X1.75 Y1
Z-.1
Z.1
X2 Y1
Z-.1
Z.1
M5 (Stops the router, again assuming you have the router power under relay control)

The above is a VERY Basic g code program, which does not include anything special.
It is meant only as an illustration of manually creating basic g code.
The same could actually be entered on the manual input line of driver software such as Mach 3.
Note: the first Y1 move is the only required entry, the second, and subsequent Y1 moves could be eliminated from the program,
since the first Y1 move would locate the tool at Y1.
Since there are no other changes to the Y coordinate, Y1 would still be the current coordinate of the Y axis.
Hope this helps you to gain a basic understanding of CNC. As I know that it can be somewhat overwhelming!
AdPrinter
 
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Re: Newbie trying to drill holes

Postby Randy » Wed May 27, 2015 3:37 am

AdPrinter wrote:Not trying to discredit Randy's suggestion, or advice.

I'm just always poking around at the edges, so always take everything I say with a grain of salt. (As President Reagan said "Trust, but verify"...) Thank you for your thoughtful posting.

There has also been some discussion of canned cycles for drilling at viewtopic.php?f=3&t=15501 and peck drilling at viewtopic.php?f=3&t=15488

AdPrinter wrote:Hope this helps you to gain a basic understanding of CNC. As I know that it can be somewhat overwhelming!


You are entirely right, AdPrinter. Sometimes a little hand-written gcode is the most efficient way of getting the job done. And in doing so, as Obi-Wan Kenobi (who was almost as wise as Mr. Reagan) said "You've taken your first step into a larger world" :)

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


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