Fix a primative onto a sketch

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perky
Posts: 33
Joined: Thu Jan 05, 2017 7:36 pm

Fix a primative onto a sketch

Post by perky »

I need to do a boolean cut with a cylinder primaive but I was wondering how to fix the position of the cylinder onto a face so that if the face moves the cylinder follows it. I can map a face to a sketch but that leaves the cylinder in place and moves the sketch instead, I want it to be the other way round.

Thanks,
Mark.

OS: Windows 7
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.16.6706 (Git)
Build type: Release
Branch: releases/FreeCAD-0-16
Hash: f86a4e411ff7848dea98d7242f43b7774bee8fa0
Python version: 2.7.8
Qt version: 4.8.7
Coin version: 4.0.0a
OCC version: 6.8.0.oce-0.17
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DeepSOIC
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Location: used to be Saint-Petersburg, Russia

Re: Fix a primative onto a sketch

Post by DeepSOIC »

Hi!
You can't stick a cylinder to a face in v0.16... but you can in 0.17! Create a cylinder first, then in the menu, pick Part->Attachment.

Maybe work around that by extruding a circle in sketch?
perky
Posts: 33
Joined: Thu Jan 05, 2017 7:36 pm

Re: Fix a primative onto a sketch

Post by perky »

Thanks. I tried creating a sketch on a face, drawing a circle and extruding, and finally a boolean cut but the fact I had used a sketch mapped to a face caused z fighting issues (maybe I did it the wrong way?). I ended up de-attaching the sketch from the face first to make it work. Then of course its position is not linked to the face any more.

I might be able to set the plane co-ordinates of the cylinder sketch to the same co-ordinates of the face's sketch using the little light blue reference button, if that can be done then the two sketches should follow each other but I'm unsure exactly how to do that.

I'm not in a hurry to find a solution though, it would be useful to know how to do it. Maybe a feature request so in the future be able to map one sketch to another so they are independent but use a common set of co-ordinates so they follow each other?

Mark.
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DeepSOIC
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Re: Fix a primative onto a sketch

Post by DeepSOIC »

perky wrote:I had used a sketch mapped to a face caused z fighting issues (maybe I did it the wrong way?).
Did you use PartDesign Pad instead of Part Extrude?
perky
Posts: 33
Joined: Thu Jan 05, 2017 7:36 pm

Re: Fix a primative onto a sketch

Post by perky »

For reference I was trying to create a cored out block. I initally used pad on one side and pocket on the other, this worked except I needed a taper which unfortunately pad and pocket don't allow (I guess I could have added a draft later but hey). So I used extrude with taper. Initially it didn't work until I detached the face from the bottom sketch, but I've just tried it again and it worked fine. I think I might have got confused somewhere along the way. If you look at the file attached I used a reversed pad for the inital base sketch, so when I change that pad say from 2mm to 3mm the bottom sketch and hence the cored out part follows it as i wanted. So all's well, it'll be finger trouble my end. Thanks for the help!
Mark.
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extrude1.FCStd
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