Question About Calculating Fillet

[Anonymous]

This may be more of a math question really, but I can't seem to get the prefect filleted edge without just playing with the numbers. I would like more of a specific formula for accuracy and parametric designs.

Basically if you have an object 2mm wide and you want to fillet both edges so it is perfectly rounded on top you would normally use half the width for the radius of fillet.

However, if one of those walls has a 60 degree angle, but the distance between both edges is still 2mm how would I go about putting in a formula to still round this perfectly as 1mm radius no longer works?

Hopefully this makes sense.

Thanks!

[KKizildemir]

Hi,

You know the length of [AV], angle of |AVB|. Now, you can see the right triangle (triangle with an angle 90°) |AVO|.

Fillet Radius = [AO] = [AV] x tan (V/2)

I hope this can help you.

Regards,

[Anonymous]

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@KKizildemir wrote:

Hi,

You know the length of [AV], angle of |AVB|. Now, you can see the right triangle (triangle with an angle 90°) |AVO|.

Fillet Radius = [AO] = [AV] x tan (V/2)

I hope this can help you.

Regards,

---

Thanks for the reply, I will have to play around with this and see if I can use the description and diagram to make this work as needed. I appreciate the help. It's a bit confusing, but I think I can work through it now.

[KKizildemir · Accepted solution]

Hi again,

I make a tiny calculator for this problem. You can use this. Please find attached.

Regards,

[Anonymous]

Thanks for the help! That's awesome and should greatly help out.

[KKizildemir]

You're welcome. See you later!

[Anonymous]

When I plug in the numbers I am getting a number slightly lower than what is needed to make this filleted properly. The number is 1.154701 and the number needed is around 1.268. Maybe I'm not understanding how this works correctly.

Sorry for the trouble. Any clarification would be greatly appreciated.

[KKizildemir]

Can you please share a screenshot of the cross section view of your fillet? And mark the length and angle?

[Anonymous]

Not sure if this is what you were asking for, but I have attached the image along with the project file.

Not sure how else to give the dimensions in the image.

[KKizildemir · Accepted solution]

Hi,

I updated the Radius Calculator to V2 due to given dimensions.

The formula is below with the reference pic.

R= (B*TAN[(180-A)/2])/(1+TAN[(180-A)/2])

[Anonymous]

Thanks so much! That worked perfectly.

I really appreciate the help.

I knew there had to be a way, but couldn't figure out the right formula.

[laughingcreek]

I'm just going to put this out there.  Math is fun and all, but I think it's better practice to let the program do the heavy lifting for you.    This is one of the rare cases where adding the fillet during the sketching phase makes more sense (usually you want to avoid fillets in sketches, and apply them to the solid instead.)

Attached is an example file.  and also below is a screen cast of using a 3point tangent sketch to create the fillet.  Note that doing it this way allows making parametric changes with out having to manually recalculate the fillet radius. 

[Anonymous]

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@laughingcreek wrote:

I'm just going to put this out there.  Math is fun and all, but I think it's better practice to let the program do the heavy lifting for you.    This is one of the rare cases where adding the fillet during the sketching phase makes more sense (usually you want to avoid fillets in sketches, and apply them to the solid instead.)

Attached is an example file.  and also below is a screen cast of using a 3point tangent sketch to create the fillet.  Note that doing it this way allows making parametric changes with out having to manually recalculate the fillet radius. 

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I really appreciate the response and the screen cast!

I didn't think about doing it in the sketch considering I applied a chamfer and then a filler.

I can create stuff half way decent depending on what it is, but I know I don't always go about things the best way or have the correct workflow.

I will try that out in the future. Parametric is definitely a huge plus though in making adjustments when needed.