can some one help punching holes in a circle?

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rebeltaz
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can some one help punching holes in a circle?

Post by rebeltaz »

So, basically, I have a ring that I need to punch several holes in, kind of like this:
test.jpg
test.jpg (29.39 KiB) Viewed 869 times
For that demonstration, what I did was just place the holes on a sketch in the YZ plane and did a reversed Pocket "through all." Doing that elongates the holes, though. What I want to be able to do is, have the holes project from the center, following the curvature of the ring, so that each hole is drilled through as a circle at the proper angle. These holes need to be a set distance apart and if at all possible, it would be great if it could be parametric so that if the distance changes, the model can follow that change. I know that I am asking a lot, but I've seen some pretty wild stuff done in FreeCAD and if anyone knows how to do this, it'd be y'all!
edwilliams16
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Re: can some one help punching holes in a circle?

Post by edwilliams16 »

In Part Design use Polar Pattern
Screen Shot 2022-05-19 at 5.46.34 PM.png
Screen Shot 2022-05-19 at 5.46.34 PM.png (39.83 KiB) Viewed 858 times
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polarpattern.FCStd
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rebeltaz
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Re: can some one help punching holes in a circle?

Post by rebeltaz »

edwilliams16 wrote: Fri May 20, 2022 3:48 am In Part Design use Polar Pattern

I did try that initially - that's basically what I was looking to do - but I could not figure out a way to get the holes located correctly and at the correct distances apart.

Something like this, but the holes have to be precisely located and, I'd really like it parametric so that the distances apart can be changed on the fly.
test.jpg
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edwilliams16
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Re: can some one help punching holes in a circle?

Post by edwilliams16 »

Here's one way. Get the angles off your sketch and use them in expressions to rotate the hole sketches.
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polarpattern2.FCStd
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Screen Shot 2022-05-19 at 7.04.48 PM.png
Screen Shot 2022-05-19 at 7.04.48 PM.png (19.74 KiB) Viewed 809 times
Screen Shot 2022-05-19 at 7.05.26 PM.png
Screen Shot 2022-05-19 at 7.05.26 PM.png (41.23 KiB) Viewed 809 times
chrisb
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Re: can some one help punching holes in a circle?

Post by chrisb »

rebeltaz wrote: Fri May 20, 2022 4:17 am Something like this,
If you have such individual positions, you cannot use patterns to create them in one go. But you can position appropriate sketches which you turn by changing their AttachmentOffset. You can give names to the angles in your sketch and use these in the AttachmentOffset as Expressions.

Ask back if you don't arrive.

Edit: I hadn't seen that edwilliams was that fast, but as we both had the same idea, it may very well be the way to go.
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rebeltaz
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Re: can some one help punching holes in a circle?

Post by rebeltaz »

chrisb wrote: Fri May 20, 2022 5:40 am
rebeltaz wrote: Fri May 20, 2022 4:17 am Something like this,
If you have such individual positions, you cannot use patterns to create them in one go. But you can position appropriate sketches which you turn by changing their AttachmentOffset. You can give names to the angles in your sketch and use these in the AttachmentOffset as Expressions.

Ask back if you don't arrive.

Edit: I hadn't seen that edwilliams was that fast, but as we both had the same idea, it may very well be the way to go.
I tried that too, kind of. I tried manually adjusting the AttachmentOffset of the example sketch but .... ooohhhh... I think I may know why that didn't work. I had offset the sketch on the Z axis to be on the inside edge of the ring THEN tried adjusting the offset angle. I should have left the sketch where it was THEN modified t he angle.
edwilliams16 wrote: Fri May 20, 2022 5:07 am Here's one way. Get the angles off your sketch and use them in expressions to rotate the hole sketches.
Thank you both so much!
Workshop_Notes
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Re: can some one help punching holes in a circle?

Post by Workshop_Notes »

chrisb wrote: Fri May 20, 2022 5:40 amIf you have such individual positions, you cannot use patterns to create them in one go...
What chrisb says is strictly correct. That is, you cannot use partterns when there is no symmetry whatsoever in your design. However, in your example, there is one line of symmetry, so you only need to do half the work and mirror it - just as the sketch by edwilliams16 shows.

May I ask why, in ed's sketch, it is showing the dimension as 23mm and not 22.5mm? Is that a modelling error or just the number of decimal places being displayed?

If you are doing a lot of these, a spreadsheet might speed up your workflow - you would need the 'pitch circle diameter' (for want of a better term), the axis offset and the quadrant in which the hole appears*. The ss could calculate the attachment offset angle. That might be quicker than sketching everything and adding constraints. You might be able to draw one representative hole, clone it and then apply the calculated angle to each clone in turn.

* extra credit, incorporate a boolean 'mirrored' function - into which you enter not Y or N but X or Y or nothing at all to denote the mirror axis.
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Shalmeneser
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Re: can some one help punching holes in a circle?

Post by Shalmeneser »

:mrgreen:
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edwilliams16
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Re: can some one help punching holes in a circle?

Post by edwilliams16 »

Workshop_Notes wrote: Fri May 20, 2022 8:17 am
chrisb wrote: Fri May 20, 2022 5:40 amIf you have such individual positions, you cannot use patterns to create them in one go...

May I ask why, in ed's sketch, it is showing the dimension as 23mm and not 22.5mm? Is that a modelling error or just the number of decimal places being displayed?
The OP image is hard to read. Is it 45 or 46mm?
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papyblaise
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Re: can some one help punching holes in a circle?

Post by papyblaise »

Funny same idea as Schlm but with straight lines
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