Help with scaling up an object in mm not in multiples

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jolson
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Help with scaling up an object in mm not in multiples

Postby jolson » Fri May 11, 2018 10:48 pm

FreeCAD v0.17 rev 13519 (win 10)

Have x-axis 15mm box (containing circles) that I need to have a x-axis of 381.1mm with all other dimensions (including circles within the box) to scale proportionately

Is this possible?
chrisb
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Re: Help with scaling up an object in mm not in multiples

Postby chrisb » Fri May 11, 2018 11:25 pm

jolson wrote:
Fri May 11, 2018 10:48 pm
Have x-axis 15mm box (containing circles) that I need to have a x-axis of 381.1mm with all other dimensions (including circles within the box) to scale proportionately

Is this possible?
Usually it is not necessary to scale the endresult in a parametric design, you rather scale certain parameters.
If that is not possible you can create a clone and scale it with a factor of 381.1/15, which is about 25,407. This factor lets me assume you want a conversion from mm in inch.
jolson
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Re: Help with scaling up an object in mm not in multiples

Postby jolson » Sat May 12, 2018 12:21 am

chrisb wrote:
Fri May 11, 2018 11:25 pm
Usually it is not necessary to scale the endresult in a parametric design, you rather scale certain parameters.
If that is not possible you can create a clone and scale it with a factor of 381.1/15, which is about 25,407. This factor lets me assume you want a conversion from mm in inch.
I appreciate the response, I will try to figure out what it means. I am hoping not to convert the measurements away from mm. I have the sketch that I made from an imported DXF (flat rectangle with circles in it, which will be the walls of a open top case, the circles will be screw mounting posts) and I know the x and y lengths in mm that the rectangle is currently, and the x and y lengths in mm that I need it to be, but I need the circles to scale up with the sides, because their placement is critical in relation to the rectangle
tommeyers
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Re: Help with scaling up an object in mm not in multiples

Postby tommeyers » Sat May 12, 2018 1:07 am

Chris,

Thanks. This was new and helpful for me. Is that only available as a capability for the Draft WB Scale?

Tom Meyers
jmaustpc
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Re: Help with scaling up an object in mm not in multiples

Postby jmaustpc » Sat May 12, 2018 6:21 am

tommeyers wrote:
Sat May 12, 2018 1:07 am
Chris,

Thanks. This was new and helpful for me. Is that only available as a capability for the Draft WB Scale?

Tom Meyers
Hi Tom, no, its also a property of a Draft Clone. Chris was suggesting that you can Draft Clone the result of a model at some point and then set its scale in one or more of the three axes. This does have its limitations and is often seen as a bit of a hack or a convenience but in most cases not really modelling "best practice". The scaling process converts edges/surfaces into splines in many cases, which can cause issues. If you scale equally in all three axes you can avoid this in some situations, but this is also OCC version dependent.

Jim
jmaustpc
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Re: Help with scaling up an object in mm not in multiples

Postby jmaustpc » Sat May 12, 2018 6:29 am

jolson wrote:
Sat May 12, 2018 12:21 am
chrisb wrote:
Fri May 11, 2018 11:25 pm
Usually it is not necessary to scale the endresult in a parametric design, you rather scale certain parameters.
If that is not possible you can create a clone and scale it with a factor of 381.1/15, which is about 25,407. This factor lets me assume you want a conversion from mm in inch.
I appreciate the response, I will try to figure out what it means. I am hoping not to convert the measurements away from mm. I have the sketch that I made from an imported DXF (flat rectangle with circles in it, which will be the walls of a open top case, the circles will be screw mounting posts) and I know the x and y lengths in mm that the rectangle is currently, and the x and y lengths in mm that I need it to be, but I need the circles to scale up with the sides, because their placement is critical in relation to the rectangle
The answer is complex, depends on what settings you have used in FreeCAD, which importer you used, and the exact thing you imported.

I very much doubt that you want to scale the holes if they are screw mounting holes, I imagine that you could we be wanting to scale their position but wouldn't the diameter need to be the same?

If there is no copy write issue, perhaps you could attach the file so we can have a look and hence suggest something?

If I am understanding what you are wanting correctly then I would consider importing the dxf into a sketch and then changing everything with constraints.
jolson
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Re: Help with scaling up an object in mm not in multiples

Postby jolson » Sat May 12, 2018 10:00 pm

jmaustpc wrote:
Sat May 12, 2018 6:29 am
The answer is complex, depends on what settings you have used in FreeCAD, which importer you used, and the exact thing you imported.

I very much doubt that you want to scale the holes if they are screw mounting holes, I imagine that you could we be wanting to scale their position but wouldn't the diameter need to be the same?

If there is no copy write issue, perhaps you could attach the file so we can have a look and hence suggest something?

If I am understanding what you are wanting correctly then I would consider importing the dxf into a sketch and then changing everything with constraints.
I ended up creating everything shape by shape from scratch and I think everything is in the right place. Currently though I have imported a separate DXF for the same project (a different part), and converted that to a sketch with 'draft to sketch', so now I have a list of 400+ sketches each a different line of the 2d dxf I imported. I will attach the DXF so you can see what I am working with. will I need to manually add constraints for each of these before I can turn it into a part?
Attachments
3308d8753be21f4ed21faa2d72edda7c08bb74df_switch.dxf
(49.96 KiB) Downloaded 5 times
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NormandC
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Re: Help with scaling up an object in mm not in multiples

Postby NormandC » Sat May 12, 2018 10:07 pm

jolson wrote:
Sat May 12, 2018 10:00 pm
Currently though I have imported a separate DXF for the same project (a different part), and converted that to a sketch with 'draft to sketch', so now I have a list of 400+ sketches each a different line of the 2d dxf I imported.
That's not normal. The Draft2Sketch tool should only create a single sketch. But I'm getting the same result here.

What gives. :?
jolson
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Re: Help with scaling up an object in mm not in multiples

Postby jolson » Sat May 12, 2018 10:12 pm

I was able to merge all of the individual lines to get one sketch at least and am exploring where to go next from there, but all of the lines in the part are unconstrained regardless
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NormandC
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Re: Help with scaling up an object in mm not in multiples

Postby NormandC » Sat May 12, 2018 10:14 pm

Edit: you posted just before me, seems you have the first step covered, read on to the second paragraph.

This is definitely an issue that needs looking at (the multiple sketch creation), but in the meanwhile, what you can do is switch to the Sketcher workbench, select all the sketches, then go to the Sketch --> Merge sketches menu. This will merge all elements into one single sketch.

Next step is to fix all the coincidences. Select the newly created sketch, then go to Sketch --> Validate sketch. Under Missing coincidences, click on the "Find" button. A pop up will tell you there are 568 missing coincidences. Close it, then click on "Fix" in the Tasks panel. Then close.

Now, the only constraints that will exist in the sketch will be the coincidence constraints just added. To further edit the sketch, you'll have to manually add missing constraints such as vertical, horizontal, equal length, etc. This will be an insane job so maybe just do it for the few elements you need to modify, and leave the others as they are.

Another possibility would be, instead of merging all the sketches into one, to merge into a few sketches that will be easier to manage.