How to "extrude a part" or "move a part into a block"; as in a sandbox / pushing a part in clay soil

chr_korff

Dear supporters, 
while constructing a mold, I thought about using "extrude on a part (not a face)" to generate a solid model of the move of the part in space, which I could then easily boolean from e.g. a mold tool block, which seems to be the easiest way to allow me to remove the part from the mold (issue of undercuts avoided).
Q1: Is this possible ? I did not find a way to extrude a part in e.g. z-direction for 2 inches

Q2: Is it possible to do the other way i.e. to move a part into a solid block and then removing all material, that is in the way, while the part moves partially into the block ?

Thanks a lot, also for a full negation on my questions -- then I can stop searching and thinking :-) 

bruce_williams

Yes, this is a common mold-making method.  You can move the part with Transform and then Boolean subtract.

chr_korff

Thanks, but if I understand correctly, just moving once + bolean gives me the difference (with a lot of undercuts)
- when you imagine a helix, there are parts that deliver undercuts, if just moved....or do you mean moving the part x-times in 0.1inch steps to get a relatively smooth mold surface ?
 

mahir

What you're talking about is sweeping a solid. OS can't do that (yet). If you're moving the part in a straight line, you can do what you want.

1. Move the tool body to its end location in the mold block by either creating it there or using transform to move it.
2. Create a plane that is normal to the direction of motion but doesn't cut through the tool body.
3. Start a sketch on that plane and convert the tool body's outer edges into sketch lines.
4. Extrude the sketch up to the tool body and also extrude in the opposite direction if necessary, merging with the tool body.
5. Use boolean to subtract the new "extruded" tool body.

Similarly, you could subtract the tool body first and then perform a cut extrude. It depends on how simple your tool body geometry is.

chr_korff

Thanks, that sounds like it seems to work !

owen_sparks

Hi @chr_korff

There is an improvement request here for a solid body sweep should you care to cast your vote.

Cheers,

Owen S.

MBartlett21

@owen_sparks

Your link is broken.

Here is the correct link:

https://forum.onshape.com/discussion/6452/sweep-remove-one-solid-body-form-another-not-a-sketch-aka-solid-body-sweep

owen_sparks

Thanks for the heads up @mbartlett21

Link fixed and you've included it too.

Cheers,

Owen S.