Can't Fillet Letter Edges

Hello,

I made this simple bolo design for a client and I cannot for the life of me get the edges of the letters to fillet. I’ve tried filleting every letter from different views (perspective and front), rebuilding the letter surface and then filleting, remaking the letters and filleting those, splitting the surface, offsetting then using blend surface.

With that said these are my questions:

  1. I was able to print a previous version of this file without the edges filleted in PLA filament and it worked okay (may have been the quality of the printer) there were some holes on the tops of the letters. Is it necessary for me to fillet the edges on this in order for it to print exactly as it is in resin for casting, that’s what we were told in school but no one seems to know WHAT happens when you don’t.
  2. If I do need to fillet the edges how do I do that? I’ve attached the 3dm below.

i was trying to answer in your meanwhile deleted topic, while i was answering the topic went down :smiley:

anyway, the letters have some very tight radii, meaning you would have to experiment with how high you can get, on the U you get away with 0.05 on the ligature you would already need 0.03 for it to work. i did not test the others but its clear that this is very much on the limit. since it seems it is more for the print not to fall apart that might already work

if you want rounder fillets you would have to rebuild you letters a bit, you could do this by using the command smooth on the joined curves before you extrude them once more, here an example with the ligature, the left is yours, the right is slightly smoothed that might already help to increase the radius for the filets. you can also only select a few controll points from the curves and smooth this locally, i just smoothed the entire letter here.

generally i guess that these fillets are meant to prevent edges to fall off as you have experienced now yourself, since these are pretty sharp without fillets and would naturally fail at some points depending on which resolution you print and which filament you use i guess, but i have too little experience with this stuff.

One other thing you can try is to offset the curves inward slightly more than the largest radius you want to put on the letters, then offset back outward with the same distance and with rounded corners. This guarantees that the fillet you will put on the edge doesn’t exceed the smallest radius.
Another way is making sure that the corners that are now almost sharp are modeled sharp, thus avoiding the tight radii the rolling ball has to go through.

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nice one!