Chamfer perimeter

(Gunter ) #1

I have never done a chamfer before. The picture shows the part I’m planning to cut.

I figure for Tool path 1 I’d cut the small hole at the top. Then cut out the whole shape with Tool path 2. And finally for Tool path 3, chamfer only the outer perimeter. I plan on using a 90 degree chamfer end mill.

My questions:

  1. How do I isolate the tool path for just the outer perimeter I need to chamfer?
  2. Do I need to set an offset?
  3. My stock thickness is 3mm. I would like to chamfer exactly half way through so to a depth of 1.5mm. Do I just set the the maximum depth of cut to 1.5mm and leave it at that?
  4. My hope is to chamfer the other side of the object as well. I understand I will need to add tabs correct?

Many thanks for for your input.
C3D Chamfer.c2d (73.9 KB)

(William Adams) #2

You would need to do a bit of vector editing to isolate just that portion of the path, then expand it to a closed region with rounded ends, then do a V carving which cuts that path.

I’d suggest offsetting a bit so that the tip of the V endmill is to the outside of the part edge.

If you could post an original I could work up instructions on doing this — unfortunately Carbide Create won’t allow one to change a closed path to an open, so to do it there you’d need to re-draw it.

(Gunter ) #3

Thanks Will. Would Fusion 360 help to change a closed path to an open? If not what would you suggest?

(Stephen Gullage) #4

This is a little explanation I did about doing chamfers to get a clean edge

To get a no chamfer area, you’d just move the line from the two tips out from the material line, so the bit is cutting air (or waste material)

(William Adams) #5

For Fusion 360 you would need to model things in 3D I believe.

If you’d post a vector file we’ll do what we can to help.

(Neil Ferreri) #6

Do you have a Fusion model? You could run a trace toolpath.

(Gunter ) #7

Thank you Stephen, Will and Neil…

I use MOI3D to model, then export to Illustrator where I save the file as an .svg. I have now created an additional path 0.8mm away from the perimeter (based on Stephen’s method). Would this work?



(Stephen Gullage) #8

If you use a 0.08" offset, the depth of cut for your vbit will have to be 0.08 before the bit touches the corner of your material (presuming you’re using a 45° vbit). Add to the depth of cut what ever amount you want to chamfer. I usually go with 0.05" to just break the edge but you may want more. Just be careful you don’t exceed the cutting height of your vbit. I usually use a 0.03" offset, as I often use a 1/4" 90 deg vbit with a cutting height of 0.125, so with an 0.08 DOC I’m cutting right in the middle of the edge.

(Gunter ) #9

Thanks for this Stephen. I actually haven’t got my chamfer bit yet. Which would you recommend a vbit or a 2 flute chamfer end mill?

(William Adams) #10

Yes, that should work.

You’d need to do the math (or just draw things up) to determine how wide the expanded stroke would need to be to get the desired chamfer. The specifics would depend on which application you’re using.

To get the desired 1.5mm chamfer we start by drawing a 1.5mm circle on the point:

Then we draw in a circle from the end of the line to a point on the circle:

Which gives us the desired dimension of a diameter of 2.6903mm

We select the lines which make up the chamfer and expand that stroke by that dimension with a rounded cap:

to arrive at:

(William Adams) #11

Stitch everything else together and export as an SVG to import into Carbide Create:

I guessed a thickness of 5.5mm to arrive at:


chamfer_example.c2d (197.9 KB)

(Gunter ) #12

Will thank you for breaking this down for me. It really helps a great deal.

Could you please explain what you mean by: “We select the lines which make up the chamfer and expand that stroke by that dimension with a rounded cap”.

Also, what kind of end mill would you suggest for this?

(William Adams) #13

Some vector drawing tools will have a tool which allows one to select an open path and expand it to become a closed one which represents the stroke.

In Inkscape one would do this by selecting the path, assigning a stroke style of the desired width with a rounded cap:

then in Inkscape do Path | Stroke to Path to arrive at:

I used a #301 and a #122 in the Carbide Create file — I think the #122 might not have sufficient flute length — please check that before committing to anything.

(Gunter ) #14

Thanks very much Will. I shall go ahead and download Inkscape and try this out.

(Stephen Gullage) #15

I’ve never used a chamfer bit, so I can’t give an objective opinion on it. I have only ever used straight flute vbits, 1/4" and 1/2"

(Gunter ) #16

Will, although I changed a few dimensions, I followed your instructions and used Inkscape to create the chamfer tool path. When I import the saved svg file into CC, there is always one path that remains open. Can’t figure out why? I checked it in Inkscape and it appears closed but in CC it appears as a few pink lines.

Could you please let me know what I’m missing? Thanks :slight_smile:

Hook test.c2d (167.1 KB)

(William Adams) #17

You can see that the paths in Inkscape are not closed by selecting the shape and filing it. (again, Inkscape allows it to be filled, which is wrong).

You need to identify where the path nodes are not connected and join them.

If you have difficulty someone more experienced with Inkscape should be able to assist, or perhaps you could do it in Illustrator — it does have tools for this sort of thing after a fashion.

If you’re inclined, it ought to be simple in Serif’s Affinity Designer which is modeled on Freehand, in which application this is a simple checkbox.

(Gunter ) #18

Apologies for the back and forth. I finally figured out how to close paths in Inkscape and now it works perfectly.

As for the chamfer operation, I chose a Vbit from the menu in CC, selected the orange chamfer toolpath but now I get this:

Could you please explain this?

Thank you for your patience :slight_smile:

Hook test 3.c2d (164.2 KB)

(William Adams) #19


The odd little extra movements are caused by Carbide Create converting everything into polylines and said lines not always matching up. Vectric Vcarve can emit G2/G3 arcs, and keeps things internally as curves, so does a better job if you’re interested in a commercial option.

(Raymond Yorizzo) #20

If you’re running Fusion 360 I suggest you watch John Saunders of NYCCNC YouTube video on chamfering.