Autocad to gcode

[JamesMI]

I've just started to learn how to use autocad and trying to convert drawings to gcode. I have to admit I really don't know what I'm doing. I can draw objects in autocad, but the only thing I can get gcode2000 to accept is 2d simple shapes. If I start putting holes or other items in it it comes out real strange. I have been unable to get it to accept and 3d drawing at all, it keeps telling me there is no usable information. I made sure to explode the drawing befor saving it to a dxf, but I still had no luck. I'll attach the autocad file I'm trying to convert using gcode 2000, maybe someone could give me a step by step walkthrough of the steps to get from a 3d drawn part to gcode. I would appreciate any help I can get.

Thanks,
James

[vladdy]

not familiar with gcode2000, opened the file, used Kcam, got wierd reversal on 'part' of the drawing..
Converted to dxf with autocad DXB utility, came out ok..
with something simple like this, all you need is a 2d dxf, and input your Z depth directly into the nc code..
not sure if this is the answer you're looking for,,but??

enjoy..

[ger21]

There are 2 free AutoCAD 2d gcode programs here that work right inside AutoCAD, My VBA G-code exporter and Bill's G-Code out lisp.

If you want to do 3D stuff, I don't think gcode2000 supports 3D. You might want to look at MeshCAM. If you need help getting your 3D models into MeshCAM, let me know. It's easy if you use solid models, just export as .stl. If you use Meshes, you need to explode them into 3D faces and save as .dxf.

[Ken_Shea]

James, here is a somewhat cleaned up and repositioned drawing and a NC gcode file for you too look at. As vladdy said your 2D drawing is all you need unless you just wanted to convert it to solids for rendering. It may be also that gcode2000 does not convert anything but 2D.

[JamesMI]

Thanks for the help,
I've given up with gcode and tried kcam, I had the same weird reversal problem. Could it be the way I'm drawing the files. If i draw just 2d everything works fine. I also downloaded the trial version of onecnc and it loads the 3d file just fine. I don't have a cnc machine, not yet anyway, so everything I'm doing is just for learning purposes. I plan to build one in the near future. I want to be able to cut what I think is 2.5d. I guess I'm just trying to figure out how to get my 3d autocad drawing to gcode using any program necessary, but the cheaper the bettter.

I've tried drawing the 3d objects use just squares and circles then using boundary and the extruding to the proper height.

I've also tried drawing 3d boxes directly then drawing cylinders and using the 3d subtract function to cut out the holes in the solid. This seems to give the same weird results in kcam as the above, but works fine in onecnc.

I've tried exploding everything before saving to dxf and that doesn't help either. I've only been using autocad for a couple of days, so maybe i'm just going about everything wrong.

I can at least do the 2d drawings and get them to work in kcam, so I guess that is a start.

I attached a photo of something i've been trying to get gcode for with only success using onecnc. I'ts just a square with filleted edges and a hole in the center.

Jamey

[JamesMI]

ger21: I downloaded the trieal version of meshcam and tried using it with no success, it says it imports 0 faces. I did explode the drawing first. I'm not sure I did everything right. I attached the file I tried to open.

Thanks
James

[buscht]

James, I am not that familiar with the programs you are mentioning other than Autocad, but I don't think that you are doing anything wrong with your drawing.

Its more of an understanding issue with the capabilities and quirks of the CAM software.

For example, your drawing8.bmp could be considered 2-1/2D or 3D depending upon the capabilities of your CNC machine and/or how you choose to process the part.

Some of the early CNC's could be programmed in X and Y, but only had a simple up/down command for the Z. Hence the 2-1/2 D. Along the way, this became the common way of describing flat parts with drilling or milling.

Your part fits this category, with the exception of the chamfer. If you have a 45 degree router bit, then a 2D part path will work. But if you want to use a straight bit, then this becomes a full 3D part and the cut path becomes lots small steps to interpolate the angle.

Not all CAM programs can take a 3D file, some work off the 2D geometry and you have to do a little creative manipulation to get the results you want, some CAM programs only use 3D files, MESHCAM for example. This program assumes that you are going to mill the entire piece to size, not simply cut the square, circle, and chamfer. Higher end programs can accept all types of CAD, but these have a long learning curve and costs $$$$$.

I would recommend you do any tutorials that came with the software demos, learn what the program requires and then try and process your parts by drawing them in the way that the CAM program wants to see them.
T

[ger21]

Try these. You need to understand how AutoCAD works and how to use it with the CAM programs you're using. The hole in the middle can be done with 2D (2.5D), but the rounded edges probably need to be 3D. You can do the hole with MeshCam's waterline machining, but it's a new feature still being developed, and may be a little buggy.

[JamesMI]

ger21: Thanks for the sample file, it opened in mesh cam just fine. I'm also glad to see that meshcam is very afordable.

I'm going to have to read a little more, I have no idea to get all the lines in there the way you did. I know there must be an efficient way of doing it. I'm going to have to just find some tutorials.

Thanks,
James

[ger21]

Those aren't lines, they're edges of triangles. Select one and go to properties and it will tell you it's a 3D face. Here's how to get those. Under Draw>Solids, box and cylinder. Subtract the cylinder from the box. Use the "fillet" command to round the edges.

Before exporting, type in "facetres" and make it 10 (it's 0.5 by default).

For MeshCAM, use File>Export, and save as .stl. Stl's load faster than .dxf's. To get the .dxf, use File>Export, and save as .3ds file. Then use Insert>3D Studio, and load it back into AutoCAD, and save as .dxf. Always use V12 .dxf's, you'll have better luck with them.

[wjbzone]

James,
I think best option for gcode from Autocad is Tahlcam. The demo is a free download, and will generate 1000 lines of gcode. Works inside Autocad. If you draw in solids you can use Modify-Solids Editing-Copy Edges to get the lines defining the path you want to machine. Tahlcam will convert the connected lines into a single path. It has a good hole routine. You can see your tool path on screen. Lots of other options.
Bill

[JamesMI]

ger21:

Thanks for all the help. I was able to export a drawing as a stl file and load into meshcam just fine. I was unable however able to import the 3ds file I exported back into autocad. I get the following error:

Command: _3dsin
Invalid file - 3D Studio file import terminatedCommand:

The stl file works great though so I will just use that, but I would still like to know what I'm doing wrong with the 3ds file export/import.

I tried to export the 3ds file just after I exported the stl. The stl worked fine like I stated above. When I click export, I get a bunch of options. I leave all as default and save the file. When I import I create a new file and try to import into there. I then get the error above. Am I missing something?

I was also wondering is meshcam widely used in the cnc communitry. It seems like a great deal for the money.

Thanks again,
James