Global rescaling of a part?

[DrBwts]

So far I have come across 2 suggested ways to re-scale a part; use insert > molds > scale or insert > features > scale.

But both of these are greyed out for me, so how do I do it? [link

http://files.engineering.com/getfil...4e56c46630&file=SixteenthSphereSurface.SLDPRT

]I have attached the file I would like to scale[/url]

It seems like a basic CAD function to me but obviously SW thinks different.

 

[DraftingMan]

DrBwts,

You can not scale a sketch.

John H. Dunten, CD
Certified Drafter

 

[EEnd]

If it is a sketch, you might be able to create a block from the sketch and apply a scale when the block is inserted.

Eric

 

[CorBlimeyLimey]

With a few changes to the sketch dimension & constraints scheme, and there is no need to scale. Simply changing one (the only) dimension, changes everything.

 

[DrBwts]

Thanks for the responses.

So if I have a fully dimensioned sketch & have one 'master' dimension, all I need to do is change that 1 dimension?

Also if the sketch were extruded for instance, then it would be possible to scale it?

 

[CorBlimeyLimey]

So if I have a fully dimensioned sketch & have one 'master' dimension, all I need to do is change that 1 dimension?

In this particular case, yes, but it may not always be that simple.

Also if the sketch were extruded for instance, then it would be possible to scale it?

That depends on the type of extrude and how it is based on the sketch, but in general, yes.

Is there a reason you want to use the Scale function. (shrinkage, plating, etc). There may be better methods to achieve what you are trying to do.

 

[DrBwts]

I am creating a mold using a 3D printer & I'm aware that there is some shrinkage associated with the process. So it would be good if I could just scale the design until I have the dimensions right to take account of this.

 

[Updraft]

There is shrinkage between the mold and the molded part and there can be differences with the 3D printing process - these are two separate issues. I think your best bet is to model the finished part in SolidWorks as you want it to be in the real world and then apply the appropriate scale factor to it in order to make the mold SolidWorks model. That way your dimensions are true and you'll have the separate and appropriate scale factor involved where it belongs.

My experience with 3D printers is not so much one of shrinkage but of "dimensional differences", i.e., some feature edges come out fat and some come out skinny. This is partly a function of the STL file since it is making faceted surfaces out of your smooth model, but it is more a function of the resolution/pixilation of the printing process. I have also found that the resolution of most 3D printers is different in the vertical (Z) direction from the horizontal (X-Y) direction. This is usually stated somewhere in the printer specs. This is not a scaling issue as almost all 3D printers do an accurate job printing to scale, though their precision is affected by the particular situation.

Have you 3D printed a scale test part such as a 25mm hollowed cube, or better yet an octagonal polyhedron? This will tell you a lot about what you can get from the printer in all directions. If you are sending your stuff to a 3D service bureau then they should be a key part of your conversation regarding what to expect from the printer.

- - -Updraft

 

[ctopher]

To make a 3D print mold, there is shrinkage, and expansion, of the mold. There is also the same with the molded part.
If you go this route, there may be some trial and error to have a good dimensional part.
Drill/tap finished holes after molding.

Chris, CSWA
SolidWorks '15
ctophers home
SolidWorks Legion

 

[DrBwts]

Thank you all for the sound advice. I'll be making the 1st print tomorrow. They have bench marked the dimensional inaccuracies of the printer, so I have pretty good idea that my design is appropriate.