No, because the knife rotates & the tip will move. When I set mine, I rotate the knife tip forward to set X, and rotate it right or left to set Y, so the zero point is in the center of the spindle.
I think real drag knife CAM software let’s you enter the offset of the tip & it compensates for the offset.
I just use a ramp in CC to align the tip at the start, and force a little overlap at the end of the path.
So you have the tip pointing toward you and “touching” a target spot on the piece and set X then rotate and jog so the tip is on the target again and set Y?
I am trying this with Vcarve Desktop which doesn’t support the drag knife gadget which supports the offset. But I can try the ramping and add in some lead in/out vectors.
Yes. To compensate for the offset, cutting a sharp corner should look something like this…
Where the radius move is leaving the tip in the same spot but rotating the center of the drag knife in the direction of the next move. So far the stuff I’ve done with it just isn’t that critical. I’m either cutting a mask for painting, or pre-cutting the mask for a V-carve so the mask edges don’t rip out.
Thanks. I will give it another go.
I manually coded similar overcuts in the hand-written G-code for:
Um, yeah, I don’t really see that happening.
I did look at dxf2gcode which is supposed to put the corner loops in but I haven’t really tried it yet.
Yeah, it’s kind of tedious, hence my working on other ways to make G-code.
After the distraction of my failed attempt to convert the SharkTooth to a drag knife I finally had a chance to do the test cuts in maxmetal.
I used a 1/8 compression bit at a DOC of .126” cutting through in one pass except for the one with the word.
The sign place I am working with makes road signs for neighborhoods and puts vinyl iver the maxmetal substrate. So she wanted to see if I could cut some profiles. I did a small sign test and then a more fancy one and then a large one about 18” wide.
It al went really well. Very little cleanup when done. There was no real need for deburring. I just ran an xacto blade across the cut edge and wiped with an old rag.
I did have an issue with Vectric Vcarve I will post about in another thread but switched to CC and all was well.
And for the coroplast I have ordered the SST drag knife. I have to leave town for a week but hope to try that when I get back.
That’s great! Looks like I’ll be buying some compression endmills (save myself some clean-up time). Sorry the Shark Tooth/xacto setup didn’t cut properly, but your test results have a lot of valuable info (of course). Thanks!
This is the one I used for this.
https://www.amazon.com/gp/aw/d/B0B6VJQP3X?psc=1&ref=ppx_pop_mob_b_asin_title
I bought it specifically for a plywood project some time back but it may get dedicated to metal and I’ll get a different one for wood.
Both Cadence and IDC have 1/8 and 1/4 compression bits that look nice, but their 1/8 bits are on a 1/8 shaft rather than 1/4 like that Spe bit.
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