Project: to model a sheet of 3mm plastic with letters formed into it via a vacuum molding process





Well this was fun.

First, even tho I've done a fair bit with MoI, thanks to Brian I now know that MoI has very versatile text capabilities! I had never noticed that before :)

In fact there are many ways to approach this project.

The best I've found so far:
place a letter as a 2d curve on the sheet surface
form an 2mm offset outside of the letter
extrude the outer curve 2mm up
extrude the inner curve >3mm down
boolean union sheet to outer extrusion
boolean subtract inner extrusion from the rest
apply fillets as required

Another method involved placing a solid letter on the sheet, shelling it and then finding myself in some strange inverted space where booleans produced unexpected results!

I noticed some of the operations took a long time. For example filleting the upper face of the S took about 18 sec, and the internal corner where the S meets the flat sheet took about 30s. Is this normal?

My machine is not fast by any means, but it handles a lot of modeling and rendering without any problems.

Anyway, any comments, observations would be welcomed :)

Hi Steve, looks like you have got a great method worked out, the results look nice.

> I noticed some of the operations took a long time. For example
> filleting the upper face of the S took about 18 sec, and the internal
> corner where the S meets the flat sheet took about 30s.
> Is this normal?

Yeah, filleting is a pretty intense number crunching operation, so it is not unusual for it to take about that amount of time. The time for that operation is directly proportional to the speed of your computer's CPU - that would certainly get faster on a computer with a faster CPU.

One thing that can also bog it down somewhat is if you have objects at a large numeric scale, like with coordinates larger than 1000 units or so. MoI computes many operations to an accuracy of 0.001 units which can be too tight of an accuracy if you have objects at a larger scale size. That is not easy for me to tell by looking at the screenshots, but you possibly may be running into some of that as well.

- Michael

Solved the problem, Michael, I'm happy to say.

I had the mesh angle turned down to a very low value. I also swithed off "detail to inflections" and now the fillets happen super fast. Nice :)

Here's another thing I found:
With some letters, S in particlar, if I fillet the vertical edges, then the top face will not fillet. It would probably be better to fillet the original 2d curves before extrusion.
EDIT I withdraw this comment. Problem solved by slightly reducing the fillet radius

By the way, it's great to be able to turn hidden lines on and off from the view menu. I don't think that feature was there in v1. And the C-plane feature will definitely come in useful.

Hi Steve, sounds like you have got things under control now!

> By the way, it's great to be able to turn hidden lines on
> and off from the view menu. I don't think that feature
> was there in v1.

Thanks, yup that is new for v2. I'll probably be putting various other view options that you may want to turn on or off relatively frequently over there where you can get at them a bit easier, rather than only on the Options dialog.

- Michael