How to add a fillet?


Hi Everyone,

I couldn’t find a way to upload a file so I’m including the onedrive link. The linked file shows a bracket on which to mount LEDs. It was easy enough to make with my very limited skills but I did want to add a fillet to strengthen the right angle joint. I can’t figure out how to do it. Can someone help? Thank you.!1172&authkey=!AFNqmFfEFZt7KPE&ithint=file%2Cskp


Here’s my newbie solution. I drew the end of the fillet, and used the follow-me tool to extend it across the back. I was left with open ends, so I had to do a little bit of retracing. I’m sure that was because I didn’t have my initial fillet properly set between the top and the curved back piece.

I’m sure that one of the pros will be along to correct me, and give you better advice!

Rear LED brackets fillet.skp (1.2 MB)


Please describe exactly where you want the fillet.

More importantly, clarify what you mean by a “fillet.” In various contexts, “fillet” can mean a fillet weld, a machined inside corner produced with a radius on an end mill, or in some broad contexts an outside corner edge break.

Please try to make your questions completely unambiguous.



I’ve highlighted the area where the fillet would be applied. Sorry for not being clearer but I assumed when I talked about strengthening it would be obvious where that would need to be done. I have crudely drawn a cross section of what I would want the fillet to look like.


That is exactly what I was trying to do and I tried the follow me tool but it did nothing. I’ll try again. Thank you.

I think I see why yours worked and mine didn’t. I started at the very edge of the horizontal portion of the bracket which made the face of the fillet at some odd angle instead of perpendicular like yours is. :smile:


Draw a cross-section of the fillet at one end, then using the Follow Me tool, drag that cross-section along the seam between the two parts. Use View > Edge Style > Edges to show or hide the edges between sections of the fillet.


It might be tricky to get the starting cross-section aligned perpendicular to the first segment. I noticed that mine was a little off, but it jumped into proper alignment as I started the drag.


Yes it leaves a little gap at each end, but then a real fillet would be unnecessarily complicated in most drawings.


A couple of comments:

@macquigg: most experts today recommend selecting the path first and then just clicking the follow-me tool on the profile. Dragging the profile along the path is much more tedious and prone to oops.

@tr3topflyer: your model is dangerously small for SketchUp. To avoid potential problems from SketchUp’s small geometry threshold, I would recommend that you scale the model up by 10 or 100 before doing much more, and then scale it back down when you are finished.


I guess you’re talking about a fillet weld.

Welds are not commonly drawn, because they’re highly variable in appearance and are typically controlled by a weld symbol, possibly supplemented by a weld specification. A drawn weld bead is generally considered “unnecessary artistry.”

If you apply a concave curved extrusion as @wawoodman did (aside from the issues at the ends), you come up with a completrely unrealistic representation of a weld bead, which is lumpy and uneven looking–more like a series of overlapped blobs. If you take the time to model the weld bead realistically, you have invested a lot of time on a non-technical definition that gives virtually no information.

It would be much more important to first make sure its identified as a weld and secondly provide some basis for sizing the bead.



@Gully_Foyle based on the size, I’m guessing that @tr3topflyer plans to take this to a 3D printer when done. If so, he does need to include the fillet because it is part of the shape not a weld.


Questions that make you guess a lot: my favorite.

Also, if it’s going to a 3D printer, the two objects need to be integrated into one. This refers not only to the present group structure but to details like unneeded internal faces and external edges. The fillet becomes perhaps the least of the OP’s issues.



Good point. Much easier to repeat the Shift-Select until I get the path just right, then do the whole thing in one click.


Mine didn’t either the first time, for the same reason! So I just closed it off where it stopped, and erased the extra lines.


Ok so I got mine to work too using the follow me tool. And actually my ends closed just fine. Thanks guys for your help and I’m sorry if my CAD language is vague. I’m not a CAD designer but a drone builder needing a part.

slbaumgartner thank you for the scaling tip as I have had problems with things like arcs because of size. Now I just have to figure out how to down scale. Will it be accurate when I shrink the model down to its proper size?


Yes, down-scaling preserves geometry, even very small geometry. The small parts issue occurs as you create the geometry, but not when shrinking it afterwards.

Probably the best way to upscale and downscale is to make a component containing your model. Move a copy away from the original and scale the copy using the scale tool (you will need to zoom extents to see the big one!). When done, just delete the enlarged copy. The changes automatically propagate to the original sized one.


So if you’re planning to 3D print this part, you need to integrate the geometry into one object with no extraneous geometry inside. Also, the “fillet” would be simpler, stronger, and less geometry if it were simply a flat bevel.

Here’s what I’m talking about:



How did you do that?


Starting with the curve at the bottom intersection of the shelf with the cylinder, produce Curve 1 with the Offset tool and Curve 2 with the Move tool (Curve 2 is a copy of the original curve. With hidden geometry turned on, use the Line tool to connect the vertices along the top and bottom of the bevel.
Extend the bevel to either side and intersect/trim with the shelf sides. All as shown:



I’ll try that. Thanks for the explanation.