View Full Version : Fookin' Probe
travesty42
04-02-2008, 11:16 PM
ARGGH. My probe is causing me hell. I do simple 2D probing of the edges of patterns. For cutting, some materials I use a V-bit and machine along the vector and everything comes out fine. However, with other materials I profile cut on the outside of the vector with an end mill. Whenever I do this it cuts larger than the pattern on two of the four sides by about 1/4" (am using a 1/4" probe and 1/4" bit). I have checked to make sure the table is square. I use the same size probe as cut bit. I save the probe as a polyline .dxf and import it into ArtCam Insignia for toolpathing. What am I doing wrong? Is it more accurate to just probe straight to shopbot and skip the ArtCam? That would suck as I need to nest several parts for each sheet of material. Plus I often need to clean the edges and corners up on the computer but this scenario happens even if I never alter the file at all. Any ideas?
Brady Watson
04-03-2008, 12:18 PM
It's been a while since I have 2D probed anything, but from what I remember, the DXF produced is offset 1/2 the diameter of the stylus. So, if you used a 1/8" stylus, then you would have to offset your DXF .0625". I do not remember if you need to offset in or out to get it dialed in.
Once you have the DXF in Insignia, you will probably want to copy the original to a new layer. Then spline the DXF using the spline tool (looks like 2 of these--> ~) to smooth it out, ignoring straight spans. Compare the splined vectors with the original DXF. Then check your dimensions & tweak as necessary.
-B
travesty42
04-03-2008, 08:09 PM
Brady-
I'll try that, thanks for the help. Thanks to the extensive probe literature
I can not remember how to set the size of the probe stylus in the system. I seem to remember at training that they had a way to do this but it escapes me.... any help?
Brady Watson
04-03-2008, 10:47 PM
Travis,
I don't believe so. But if you remember what stylus you used, it should not matter. Just as the center of the bit sits over your 0,0 point, the points/coordinates measured by the probe correspond to the center of the stylus. So as long as you remember to offset the DXF (I believe inwards by 1/2 the stylus diameter) then you should be OK.
-B
travesty42
04-06-2008, 04:03 AM
Brady-
In lieu of offsetting the dxf, what you're saying is that if I choose to machine along the .dxf vector rather than doing a profile cut it should all be good? (assuming the stylus and the bit are the same size)That makes a lot of sense to me, why didn't that ever occur to me? Everything sounds so logical when you say it. Thanks again for the help, you are a wealth of knowledge.
Brady Watson
04-06-2008, 11:54 PM
Travis,
That will work in theory, but I personally like to see the actual DXF & edit it before cutting. If you part has ANY sharp outside corners, they will not show up in the scan. You will have to manually square them up & generally smooth out the shape. What I like to do is put the imported DXF on it's own layer & lock it. Then on a new layer (both layers visible) trace out & node edit over the original scan, eliminating extraneous nodes and squaring up places that need to be squared. Then offset as needed, comparing measurements to the original. Then just toolpath the new vector. This method will yield the best cut quality. I do this most of the time when customers send me jagged vectors and it usually doesn't take more than a few minutes if you had enough practice with node editing.
-B
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