[SOLVED] Sheet Metal: Indexing objects from bend?

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kevinz
Posts: 68
Joined: Fri Oct 18, 2019 2:58 pm

[SOLVED] Sheet Metal: Indexing objects from bend?

Post by kevinz »

Hello,

I'm very new to FreeCAD, and especially new to the Sheet Metal Workbench. I'm not even sure that what I want to do is good engineering practice. I'd like to bend a sheet metal object and measure and place objects on the bent flange in reference to the bent edge. Can this be done?

I've created a simple file to illustrate my issue. In this file, I:
  • Created a 10 x 10 object and padded it to 2mm.
  • Extruded and bent one of the edges to a 120 degree angle (so it's not in any of the default planes)
  • Created a local datum plane on the bent flange
  • Created a new sketch on this face and created a circle that I'd like to pocket for a screw hole
The new datum plane ended up with an axis down the middle, so I could index the center of the hole to that, but I'd like to set the height based off of the outer surface of the bend (Ideally, I'd like to base it off of the INNER surface of the material, but once I figure out the outer, I imagine the inner is similar). The datum also created a horizontal axis about three-quarter of the way down the face, seemingly at random, so I don't want to index off of there. The radio that I'm designing this bracket for has screw holes on the sides, that I can measure down from the top surface. It seems like this is the dimension I should sure to parametrically set their location.

Thanks for any suggestion or advice, both on the specific problem, and also on whether the way I'm going about it is a good idea or not.

-Kevin
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SMW_LocalDatum.FCStd
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Last edited by kevinz on Sun Jan 23, 2022 6:19 pm, edited 1 time in total.
kevinz
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Re: Sheet Metal: Datum line from intersection of two datum planes?

Post by kevinz »

I've made some further progress, but haven't arrived at a solution yet.

Attached is my original drawing, with two datum planes added, one on the interior face "before" the bend, and the other on the exterior face "after" the bend. As you can see, they intersect. Now, if I could just find a method of generating a datum line on the intersection of the two datum planes. I've found a reference to a macro that does it, but I have never worked with macros, and would just like to learn a manual way to do this, as I don't think it will come up that often. The Exterior Geometry tool in Sketcher looks like it would work, but the datum planes are part of the Part Design workbench, and don't seem to work with the Sketcher tools.

Thanks for any guidance or advice anyone has to offer.

-Kevin
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SMW_LocalDatum.FCStd
(18.39 KiB) Downloaded 10 times
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Shalmeneser
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Re: Sheet Metal: Indexing objects from bend?

Post by Shalmeneser »

'Horizontal axis' of the DatumPlane is at mid-height.
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Capture du 2022-01-19 21-24-15.png
Capture du 2022-01-19 21-24-15.png (28.4 KiB) Viewed 1125 times
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Shalmeneser
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Re: Sheet Metal: Indexing objects from bend?

Post by Shalmeneser »

Change name of file each time, otherwise it's PITA.
kevinz
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Re: Sheet Metal: Indexing objects from bend?

Post by kevinz »

@Shalmeneser, thanks for your response. I'll be sure to change file names in the future.

I'm confused about your comment, "'Horizontal axis' of the DatumPlane is at mid-height." I don't see how this helps me. 'Mid-height' of the datum plane is arbitrary. I need to measure from the intersection of the plane on the 'interior' face before the bend with the plane on the 'exterior' face after the bend. I want to create a hole a certain height perpendicular to the interior face in the exterior face. Sorry if this isn't clear. I was trying to create a drawing of what I'm trying to do, but the Draft workbench defeated me in the time I had.

-Kevin
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Shalmeneser
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Re: Sheet Metal: Indexing objects from bend?

Post by Shalmeneser »

Hand-writing drawing ?
kevinz
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Re: Sheet Metal: Indexing objects from bend?

Post by kevinz »

Here's a picture I finally created (with LibreCAD):
Screenshot from 2022-01-20 15-51-14.png
Screenshot from 2022-01-20 15-51-14.png (6.81 KiB) Viewed 1035 times
Thanks, again, for your interest and help.

-Kevin
kevinz
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Re: Sheet Metal: Indexing objects from bend?

Post by kevinz »

Better diagram, I think:
Screenshot from 2022-01-20 15-56-18.png
Screenshot from 2022-01-20 15-56-18.png (8.25 KiB) Viewed 1029 times
-Kevin
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Re: Sheet Metal: Indexing objects from bend?

Post by Shalmeneser »

:?:
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SMW_LocalDatum_SHALM.FCStd
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kevinz
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Re: Sheet Metal: Indexing objects from bend?

Post by kevinz »

@Shalmenester, thanks again, for responding.

The FreeCAD document you sent seems to show that you know how to do this. Unfortunately, it didn't show ME how to do it. After working with it for a couple of hours, to see how you anchored the vertical line between the two faces, I finally realized that you hadn't used the Sheet Metal workbench at all. The object you created was formed from an Additive Pipe and didn't used any 'Bends' (as created by the SMWB) at all.
Screenshot from 2022-01-21 14-41-37.png
Screenshot from 2022-01-21 14-41-37.png (48.23 KiB) Viewed 932 times
Body001 is the body on the right.
Body001 is the body on the right.
Screenshot from 2022-01-21 14-41-53.png (26.7 KiB) Viewed 932 times
Since you didn't provide any commentary, I have to ask: are you saying that my operation can't be done on an object generated by the Sheet Metal WB? Or, were you just trying to show me an alternative way to do the same task?

I specifically want to perform the task using objects created by the Sheet Metal Workbench. I hope to get this object produced by a sheet metal prototyping shop, and don't think that they can work with something that can't be unfolded.

-Kevin
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