Make holes/pockets in the side of cylinders

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rytmenpinne
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Joined: Thu Apr 12, 2012 3:02 pm

Make holes/pockets in the side of cylinders

Post by rytmenpinne »

Is there a reliable way to make accurately placed holes, pockets or even pads for that mather, on the side of cylindrical objects ie on a curved surface. I found one way for making a few(3) holes, I simply made a separate object, an even triangle and made pads on the faces and then made a cut with it on the cylinder. However, I have another cylindrical object wich needs alot more holes in it evenly distributed around the cylinder. So this seems like a cumbersome/unreliable way to do it. I tried the polare pattern feature but it seems to be made to copy features on a face rather than around an object.
rytmenpinne
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Joined: Thu Apr 12, 2012 3:02 pm

Re: Make holes/pockets in the side of cylinders

Post by rytmenpinne »

Thank you! Still quite abit of a workaround, and I don't seem to be able to combine it with polar pattern wich would be helpful...
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ppemawm
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Re: Make holes/pockets in the side of cylinders

Post by ppemawm »

The attached file shows one simple way of creating multiple holes in a cylinder.

1. Create a box on the top of the cylinder such that one vertical edge lines up with the sketch axis of the cylinder.
2. Select the overhanging face of the box and create a sketch of the hole you wish to remove from the cylinder
3. Pocket the hole to the desired depth
4. Select the pocket in the Project tree and then select PolarPattern from the task pane.
5. In the PolarPattern task pane, for the axis choose Select Reference../Select an Edge and pick the edge of the box that aligns with the first cylinder axis.
6. Input the angle that includes all of the pockets
7. Input the number of occurrences insuring that they will not overlap.

If the holes are too deep or too large a diameter such that multiple holes will overlap, then the PolarPattern will likely fail.

Hopes this helps.

(I am using Windows 7,V0.13,Rev 1828)
Attachments
multi_pocket_cylinder.FCStd
Cylinder with multiple radial holes
(73.6 KiB) Downloaded 1095 times
"It is a poor workman who blames his tools..." ;)
rytmenpinne
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Re: Make holes/pockets in the side of cylinders

Post by rytmenpinne »

Aaah, thank you a thousand times!
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NormandC
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Re: Make holes/pockets in the side of cylinders

Post by NormandC »

ppemawm wrote:The attached file shows one simple way of creating multiple holes in a cylinder.
Nice one ppemawm. :)

I thought polar patterns were limited to the plane of the initial sketch but obviously it is not so.
rytmenpinne wrote:Thank you! Still quite abit of a workaround
I came up with this workaround because of the planar face support rule. From what I understand, we will no longer be limited with this in the next release of FreeCAD.
V12StealthHunter
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Re: Make holes/pockets in the side of cylinders

Post by V12StealthHunter »

Now 8 years later, is this workaround still the best method for making holes around a tube?
drmacro
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Re: Make holes/pockets in the side of cylinders

Post by drmacro »

V12StealthHunter wrote: Tue Dec 07, 2021 5:14 pm Now 8 years later, is this workaround still the best method for making holes around a tube?
Why do you consider this a workaround?

It seems a legitimate way to accurately place holes around a cylinder.
Star Trek II: The Wrath of Khan: Spock: "...His pattern indicates two-dimensional thinking."
V12StealthHunter
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Re: Make holes/pockets in the side of cylinders

Post by V12StealthHunter »

drmacro wrote: Tue Dec 07, 2021 5:27 pm Why do you consider this a workaround?
The common approach is to draw a sketch or pocket on the surface. For tubes, this does not work and you are met with an error. Hence the method described in this thread does not feel like its a natural or intuitive workflow in FreeCAD. It feels like a workaround for an error that only if you visit the forums, you would learn how to workaround.
edwilliams16
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Re: Make holes/pockets in the side of cylinders

Post by edwilliams16 »

For a cylinder with axis along the z-axis, attach a sketch to the xz-plane, translate its attachment by the cylinder radius, sketch a circle, pocket, then do a polar pattern around the z-axis. This way you don't attempt to attach to a surface- curved or no.
pocket_cylinder.FCStd
(68.06 KiB) Downloaded 136 times
EDIT
You can make this more parametric by setting the sketch translation to the cylinder radius with an expression.
Screen Shot 2021-12-07 at 8.06.05 AM.png
Screen Shot 2021-12-07 at 8.06.05 AM.png (54.23 KiB) Viewed 4439 times
Attachments
Screen Shot 2021-12-07 at 7.57.00 AM.png
Screen Shot 2021-12-07 at 7.57.00 AM.png (38.67 KiB) Viewed 4477 times
Last edited by edwilliams16 on Tue Dec 07, 2021 6:31 pm, edited 1 time in total.
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