Thread: Sketch fillet between 2 non intersecting arcs

1. Sketch fillet between 2 non intersecting arcs

I'm fairly new to SW, and this is something I haven't figured out how to do. As an example, I draw an arc with a 1" dia at 0,0, and another arc with a 1" dia at 1.375, .375

Now, I want to draw a .250r fillet between them. When I try to do it, SW gives me an error saying the 2 arcs don't intersect.

I can do it in Mastercam or Autocad, and it's a no-brainer, it just does it.

This is something I need to do a lot, mainly in pockets with curved walls. I can get it to work by figuring out the arc center for the fillet, but that's time consuming and needless. Is there some other function I'm not aware of to do this?

TIA

2. If it were me (I don't know Solidworks), I might create a circles .250 larger than the two original arcs, and draw a .250 circle at their intersection, and it would be tangent to the two other arcs. Other than that, a fillet between the two arcs should work.

3. Originally Posted by Larry Dickman
I'm fairly new to SW, and this is something I haven't figured out how to do. As an example, I draw an arc with a 1" dia at 0,0, and another arc with a 1" dia at 1.375, .375

Now, I want to draw a .250r fillet between them. When I try to do it, SW gives me an error saying the 2 arcs don't intersect.

I can do it in Mastercam or Autocad, and it's a no-brainer, it just does it.

This is something I need to do a lot, mainly in pockets with curved walls. I can get it to work by figuring out the arc center for the fillet, but that's time consuming and needless. Is there some other function I'm not aware of to do this?

TIA
You will have to draw in the .250r arc near were you want it and add a "Tangent" relation to the other 1" dia arcs. Kind of a PITA. OR

This is hard to explain, its kind of a hidden function. Use the line command
1. make a straight line
2 release mouse button leave cursor on line
3. push down button and drag cursor back down the line, then drag out in a circular motion off end of line.
4 You should get a arc.
5 repeat #2 and #3 on the arc.
6. do #5 on the arc

You will have to go back and dimension them.
It takes a bit to get used to.

Mike

4. I'm still a little unclear of what you are trying to do but I took a guess and posted some screenshots that may be helpful. Anytime I make a filet/round in a sketch I like to make a circle, and then connect it to something else via a tangency relation, and then I trim off the unused section (trim-to closest). I'm used to an older version of SW which had some issues, and this is a method that I had success with so I stuck with it.
Was my guess correct or are you trying to do something completely different?

-Matt

5. Thanks for the replies. That's exactly what I was trying to do. Seems like a lot of extra steps though. I might have a pocket with all curved walls, and 30 or so fillets. Seems like a PITA, I was hoping there was an easier way.

I guess what I really don't understand is why the fillet function won't do it. If Mastercam could get it to work, it can't be too difficult.

6. Originally Posted by Larry Dickman
Thanks for the replies. That's exactly what I was trying to do. Seems like a lot of extra steps though. I might have a pocket with all curved walls, and 30 or so fillets. Seems like a PITA, I was hoping there was an easier way.

I guess what I really don't understand is why the fillet function won't do it. If Mastercam could get it to work, it can't be too difficult.
Maybe it would be faster using the "Feature" fillet routine after putting in the rough pocket, instead of the "Sketch" fillet before pocketing. I usually stay away from sketch fillet if possible. The "feature" fillet has more power and less mouse clicks overall.

Mike

7. Originally Posted by Mike 1948
Maybe it would be faster using the "Feature" fillet routine after putting in the rough pocket, instead of the "Sketch" fillet before pocketing. I usually stay away from sketch fillet if possible. The "feature" fillet has more power and less mouse clicks overall.

Mike
Only problem I see there, if I have a number of non intersecting circles that make up the pocket walls, I don't have a chain that I can extrude.

8. Originally Posted by Larry Dickman
Only problem I see there, if I have a number of non intersecting circles that make up the pocket walls, I don't have a chain that I can extrude.

I think I see what you're trying to do, and it makes me wonder if maybe it might be easier to define your pockets differently. Is there a simple example part you can share that has a fully defined pocket the way you want it? It would be easier to suggest alternatives if we could see an example.

I'm no SW expert, but if there's one thing I have learned, it's that when something seems more difficult than it should be, there is always a better way to do it.

One possibility is to draw an endpoint arc from one circle to the next, then add tangent relations and dimension.

C|

9. Originally Posted by cygnus x-1
I think I see what you're trying to do, and it makes me wonder if maybe it might be easier to define your pockets differently. Is there a simple example part you can share that has a fully defined pocket the way you want it? It would be easier to suggest alternatives if we could see an example.

I'm no SW expert, but if there's one thing I have learned, it's that when something seems more difficult than it should be, there is always a better way to do it.

One possibility is to draw an endpoint arc from one circle to the next, then add tangent relations and dimension.

C|

Here is a simple example. The first pic is a view of the pocket. The second view is the geometry. The geometry in green are the arcs and lines that are defined on the b/p. The geometry in red are fillets in between them all. This was drawn in MC. I drew all the Green features, then added the fillets. 2 mouse clicks per fillet is all it takes, no extra geometry, no trimming, just click around the chain and it's done.

10. Use the offset entity using the initial set of holes as the source to begin creating your pocket. You should then have mostly intersecting arcs between which you can fillet.

The big benefit to doing that is that if you change the diameter of your holes, the pocket will update automagically.

11. Originally Posted by Larry Dickman
Here is a simple example. The first pic is a view of the pocket. The second view is the geometry. The geometry in green are the arcs and lines that are defined on the b/p. The geometry in red are fillets in between them all. This was drawn in MC. I drew all the Green features, then added the fillets. 2 mouse clicks per fillet is all it takes, no extra geometry, no trimming, just click around the chain and it's done.

Interesting part. My first thought (as an engineer) is, do to the pocket walls really have to be that complicated? But it sounds like you are working with someone else's part, so that doesn't really help you any.

The way I would probably approach this is to create offset circles for each of the defined holes. Then sketch in the fillet arcs, and add tangent relationships and dimensions. Then use the trim tool to clean up.

It seems this is one of those occasions where MC has a specialized sketch tool (among many others) that just happens to be perfect for the job. Whereas Solidworks takes a simpler approach with fewer sketch tools that are more universal. It makes sense in that SW is geared toward 3D modelling, where MC is based on 2D sketching. Personally, having learned both MC and SW at the same time, I found that SW is far more friendly and "fun" to use, where MC always seems a chore. But, I digress.

C|

12. Thanks to all for the suggestions. It appears that drawing the fillet arc, then making it tangent to the other arcs is the way to go.

So far, Solidworks is the only cad program I've used where this was an issiue, I'm just curious why. Maybe because they want you to define relationships between all the elements in the chain?

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