Help with fillets in my design

[Anonymous]

I'm designing a clutch lever for a motorcycle, and i'm trying to add the fillets in so it's nice and smooth and no sharp corners to really cut yourself on.  I had it all perfect, but then i needed to modify the sketch, and shorten the lever.  That made me redo the fillets, and now there is 1 section that I cannot get it to work.  The top portion came out just how i want, but the bottom will not.   Most of the section i'm having problem is this.  It goes from a 1mm -4.5mm (that worked), then a 4.5mm constant, to a 4.5-1mm variable, which then joins an existing 1mm fillet for the rest of the part.

Can someone please take a look at my design and assist me?  I'm on fillet 52 (i really should only be on fillet 4 or so i've tried so many different ways) and am about to rip my hair out

https://a360.co/2REmg2d

I have colored the sections in question red

Thank you

Wood 

[Anonymous]

I looked at your model and one of the reasons I believe you're having trouble is because of the order of operations. Rule number one for applying fillets, work from the larges radius to the smallest radius.

If you are trying to apply say a 5mm radius fillet that runs through and area that already has a 1mm fillet, the 5mm fillet will likely fail. Think about where you want your biggest radii, apply those first and after this move to smaller and smaller radii.

Cheers.

[Anonymous]

Okay. I’ll definitely try that.

[Anonymous]

Also, remove all the secondary cutouts and apply the larger aesthetic blends/fillets first. You'll have better continuous edges and the fillets are more likely to work. Once the body with the larger fillets is finished apply all your square angles cutouts from the main shape as a secondary machining operations.

This is also how you would approach it in the real world. The lever would be cast/forged into it's smooth shape, after forging they would perform secondary machining to make the square angled cutouts, holes etc. Often times this works best in CAD as well. Start with the basic form and finish that first. Once the basic form is finished apply detailing features. holes, cutouts, etc.

[Anonymous]

I’m completely self taught besides a quick intro to cad 15 years ago.
I went with the approach of function then form. Get a working model that fits and then try to make it pretty.

All of those secondary cutouts are how the unit attaches to the clutch master cylinder and how it actuate the system

[Anonymous]

Sure I get that, my stuff has to fit on other pieces as well. But there's no reason why you can't put those secondary cuts at the very end of the model. You will need a body first to be able to apply those secondary cuts. 

I do quite a bit of complex stuff in my work. If we have to have specific geometry that needs to be dimensionally correct at the end, often times I will put a reference sketch in place right at the beginning of the part, just to make sure the material for the secondary operation will be there. Make the main body and apply rounds before making the final cuts. I believe you will be much more successful with your modeling if you take this approach.

When you think about it, this actually agrees with form follows function for the cad model. You need to have a body and an edge before you can apply a fillet. The fillet form is a function of the body and it's edges.