Transfer shapes onto a surface

ProApe

Hello,

I would like to mill a few millimetres into the front of this birdhouse to create the shape of the eyebrows, moustache, nose and beard so that they are easier to attach.
How do I transfer these shapes to the surface?
Please note that many sketches are red, but they still work.
I keep getting the message ‘Some external references are missing’ even though there are none. How can this be explained?

Kind regards

Proape

https://cad.onshape.com/documents/d940dcd8b4c6c3c035b8a57c/w/5d4baded73310cab01c96407/e/b0dd718eb7112c2ddf2849c7?renderMode=0&uiState=69375c8ed96c3a3307e2c45e

glen_dewsbury

Try Boolean subtract.

https://cad.onshape.com/documents/21f79bfbbd4f4baa1fb663e0/w/ab0d3227dbe63b38add537ce/e/ee2c386ca6e2c21d770d3421

ProApe

Hi,

It's actually quite simple once you know how!
How can I enlarge these recesses by 0.1 mm so that the parts fit in without having to grind them down?

Kind regards

ProApe

robert_scott_jr_

Move Face should do it. However, the Boolean Subtract feature you used has an 'offset' selection that'll do the job. - Scotty

ProApe

When I open Boolean, these sections are there, but as soon as I tick the box next to Offset, they disappear.

But Move Surface works very well and is easy!

ProApe

So I enlarged the face of these cut-outs, which were created by the Boolean operation, by 0.1 mm.

When I then opened the drawing with the parts that are used, the refresh symbol was active.
So I wondered whether enlarging the cut-outs would automatically enlarge the parts as well, which would of course defeat the purpose of the exercise. This cannot be seen with the naked eye because it is only 0.1 mm, and I cannot measure it either because there are no straight surfaces – except actually on the nose, but I didn't think of that straight away.

So I wanted to test this and created a new document with an extruded rectangle (Extrude 1) and a smaller extruded rectangle on top of it (Extrude 2). I wanted to subtract the smaller one from the larger one using a subtract Boolean operation, then enlarge the area of the section with Move Face so that it was visible (and I could measure it because the lines are straight).
But now the large extruded rectangle disappears, and I don't understand why.

Why does it disappear?

https://cad.onshape.com/documents/d6c1f414642d8a552dd6b4d7/w/d8d15c8cc32197d034d18f44/e/860bcd8641859567edf46eee?renderMode=0&uiState=69381fe18808f7bd6303802e

glen_dewsbury

The 2 parts you drew do not overlap. Nothing to subtract. Your Boolean selects the same part as tool and affected part.

Notice in my sample that the extrude of part 2 is in 2 directions to provide the overlap.

https://cad.onshape.com/documents/d2490294920ed90dee541243/w/631cae6aedb3b030b8325c86/e/7bb19a0e06113b2a9ba10cd3

ProApe

But I put the sketch of the smaller part straight on the top of the bigger one.

And why doesn't it appear when I select Extrude 1? It only appears when I make a double click to open the extrusion dialogue.

glen_dewsbury

Your Boolean subtracts part1 from part1. Your target needs to be part1 and tool is part2 with keep tools checked. Part2 needs to be extended into part1. I used second extrude distance to overlap the parts and new for part2. For the clearance use offset during the Boolean. You'll have to select the faces around part1 for the offset.

ProApe

Okay, that's understandable and logical, but in my example there is only one part, even though I created two. So I can't subtract one from the other if there is only one in the Boolean dialogue.

glen_dewsbury

Get rid of your boolean and restart with a new boolean following instructions above. When you subtract part1 from part1 you eliminate part1 and part2 steps up in the list to become part1.

ProApe

All that is not so easy! I'll do my very best ;)

Thank you for your patient help!

glen_dewsbury

Here's an other version that may help to understand. Open each feature in order so you can see the build method. This one uses a move face to get the overlap instead of extrude in both directions which may be easier to understand. 😀

My main computer is on the fritz so am working with old lap top for the moment so I can't even get screen snips.😒

https://cad.onshape.com/documents/d2490294920ed90dee541243/w/631cae6aedb3b030b8325c86/e/182ba87cd2cf8077d53d056b

ProApe

Okay, I think I finally understand: it's not enough that the small part was created on the large part, there must also be an intersection between the two, and this intersection corresponds to the material that is removed from the large part by the Boolean abstraction.
So logical ;)