Changing origin on step file

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keltel
Posts: 57
Joined: Fri Oct 15, 2021 11:52 pm

Changing origin on step file

Post by keltel »

Hello.

I have downloaded some step models for inclusion in an assembly. These models have origins that are inconvenient for placement in the assembly. Example: they are often at some depth within the part and I'd like them to be on the base. How can I manipulate the step file to alter the origin?

TIA. Kel.
drmacro
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Re: Changing origin on step file

Post by drmacro »

There are a number of ways to do it.

You could use the macro discussed here: https://wiki.freecadweb.org/Macro_MoveToOrigin

You could use the Manipulator workbench (See Tolls>Addon manager to add workbenches).

You can use the Edit>Placement (If you have a particular point on the object that is desired to be at origin, note the coordinates, enter the negative values in the Translation values for X,Y,Z, and hit Reset.)
Star Trek II: The Wrath of Khan: Spock: "...His pattern indicates two-dimensional thinking."
keltel
Posts: 57
Joined: Fri Oct 15, 2021 11:52 pm

Re: Changing origin on step file

Post by keltel »

I have tried to use the Manipulator workbench. I have tried moving the object with reference to the datum plane / line and then export as another step, but I see no difference in the origin for that step when I place it in an assembly. Can you give some hint on how to do that? (I would rather not enter negative translation - leaving z as zero would leave things much neater and easier for me to continue with).
keltel
Posts: 57
Joined: Fri Oct 15, 2021 11:52 pm

Re: Changing origin on step file

Post by keltel »

I found it. I need to export with a datum point - datum line / plane do not work.
drmacro
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Re: Changing origin on step file

Post by drmacro »

keltel wrote: Tue Oct 19, 2021 12:44 pm I have tried to use the Manipulator workbench. I have tried moving the object with reference to the datum plane / line and then export as another step, but I see no difference in the origin for that step when I place it in an assembly. Can you give some hint on how to do that? (I would rather not enter negative translation - leaving z as zero would leave things much neater and easier for me to continue with).
The internal coordinate data (in STEP, IGES, etc.) is such that it is defined in specific global coordinates.

So, any move apply to the object is lost when you add it to another container, as you are technically doing with an assembly.

Try putting the STEP object in a Part Compound, then use the macro to move the STEP object (note: not the Compound, move the STEP in the compound). Then try using the Compound in the assembly.

(other suggestions may be offered...this is just what I can come up with before more coffee... ;) )
Star Trek II: The Wrath of Khan: Spock: "...His pattern indicates two-dimensional thinking."
drmacro
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Re: Changing origin on step file

Post by drmacro »

BTW, is the STEP file small enough to post here?

I'd like to look at it's data.
Star Trek II: The Wrath of Khan: Spock: "...His pattern indicates two-dimensional thinking."
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easyw-fc
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Re: Changing origin on step file

Post by easyw-fc »

keltel
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Re: Changing origin on step file

Post by keltel »

Here's the step file.

BTW, your picture above is timely! I am just trying to make a T-Slot sketch so I can do any length extrusion / pad. I tried to find something online but failed - I am after a 90 x 45 - looks similar to what you have. Drawing one is proving to be a PITA. Can you point me to where I may be able to find something I can import into sketcher? Or a good tutorial on how best to tackle such a sketch? (I started with a 90 x 45 rectangle and then tried to add some cutouts, etc. - it quickly became a big mess).
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HDF25.stp
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drmacro
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Re: Changing origin on step file

Post by drmacro »

keltel wrote: Tue Oct 19, 2021 2:13 pm Here's the step file.

BTW, your picture above is timely! I am just trying to make a T-Slot sketch so I can do any length extrusion / pad. I tried to find something online but failed - I am after a 90 x 45 - looks similar to what you have. Drawing one is proving to be a PITA. Can you point me to where I may be able to find something I can import into sketcher? Or a good tutorial on how best to tackle such a sketch? (I started with a 90 x 45 rectangle and then tried to add some cutouts, etc. - it quickly became a big mess).
There are a variety of ways to approach it. Most newer users attempt to sketch the entire cross section, ultimately create a mind numbing constraint layout and over complicated sketch.

IMO, it is best to sketch only the lowest common denominator portion of the cross section (half, quarter, etc.), constrain that, Pad, and then Multitransform.
Star Trek II: The Wrath of Khan: Spock: "...His pattern indicates two-dimensional thinking."
keltel
Posts: 57
Joined: Fri Oct 15, 2021 11:52 pm

Re: Changing origin on step file

Post by keltel »

I have found some DXF models but not sure how to convert to sketch. I will post a new forum topic. Thanks.
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