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Router Question – Interior vs. Exterior angle smoothing
Howdy
This is going to be a tricky one to explain, but hopefully I can communicate what I’m needing help with here.. bear with me.
We run a Zund L-3000 CNC cutter for our cutting needs. Currently one of the products we offer utilizes contour-cut lettering or graphics inset into a background material. We cut out the letters, then remove maybe .25" of background substrate in the shape of the same letters, and "plug" the letters into that negative space. For this example, pretend we’re using 1" gator for both the letters and the background plate. Make sense so far?
The problem we’re encountering is this.. we use a router bit to cut out the letters and to carve the space for the letters to set into.. this router bit is a 1/8" bit (sorry for not using metrics, but hopefully it won’t really matter).
What happens is that on the *exterior* angles of the letters, the router cuts a sharp point. On the *interior* angles, it is limited to cutting a corner that basically is an arc with a diameter of 1/8". Does that make sense?The opposite problem happens to the shapes we "carve" for the letters to plug into.. the interior angles are sharp, but the exterior ones have a rounded corner, from the round drill bit. Obviously, when you go to put the letters into the spaces, there are sharp angles where we need rounded ones and rounded corners where we need sharp ones, if everything is to fit nice & snug.
We can fix this by hand in the cut files, going in and rounding each corner to the tolerances of a 1/8" drill bit, but that seems like a waste of time. Does anybody know of any software or plug-ins (currently we use iCut on the cutter and Illustrator CS2 for our design needs) that can go in and change all angles to be "compatible" with various-sized router bits? I’ve tried a couple plug-ins for Illustrator that round corners according to various parameters, but the problem is that even if you enter a certain number for the rounding action (in this case 1/8"), if the angle is extremely acute, the rounded corner that results would *still* be too small for the bit. What we’re looking for here is something that will round ever corner on a corner-by corner basis to be "big" enough to accommodate a 1/8" bit, while not going over 1/8" diameter, if at all possible.
Anyway, after that ridiculously long explanation, I’m hoping somebody has found a workaround for this issue.. I can’t imagine we’re the only ones who have had this problem, and there’s got to be a better way to fix it than by going in by hand and manually changing every corner in the artwork 🙁
Ideas?
Thanks!
J -
3 Replies
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Programs like Profilelab will enable you do to inlays much easier as it will work out both male and female toopath strategies with the bit diameter in mind and will do the offsets etcautomatically.
Coreldraw X3 has a fillet function as well and can take a complex closed shape and fillet all angles to whatever radius you want. For example you can take a star and fillet the points to 1/8" as well as doing the same to the sharp angles between the "legs" of the star.
Profilelab will cost a lot , corel is cheap yet is will have much less functionality for your cnc router.
If you want to fillet angles one by one , Autocad will do so as well , an old copy of 12or 14will work rather than the latest versions. -
I run Engravelab and have done a couple of jobs where I have inlayed brass into wood. Utiising the MALE and FEMALE toolpath option automatically offsets the toolpath to allow the cutout to drop into the inlay. My only problem is the taper angle on the cutter, but to rectify that I will have to purchase a new spindle.
Having used CNC lathes anf milling machines I have always had to calculate tool offsets manually and its a pain at times. Wish I had the sftware back then to do it!!!!If this is something you a lot, you may have to think about upgrading software.
Cheers
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Thanks for the replies guys, I’ll look into those options! 😀 Ive heard lots of people talking about Corel, but I’ve never tried it. Budget would be a concern, so I’d have to keep that in mind if I were to suggest a solution. Dang budgets.
It’s not something we really do a *lot*, but we do it on occasion, and the sales guys are looking to push it pretty hard I think, so there may be much more in the future. We’ll see…
Anyway, I’ll keep poking around and see what I can find out.. thanks again!
J
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