On 9/4/2024 4:45 PM, Bob Carlson wrote:

https://github.com/openscad/openscad/issues/3781
File scope $variables ignored if a file is used by another file

https://github.com/openscad/openscad/issues/3881
Scope & changes to $special variables in "use<>" context

And I have an idea for that, but it's dependent on the object stuff that
you mention.  (Or at least the most object-y stuff that I'm aware of.)

https://github.com/openscad/openscad/pull/4478
Objects, geometry as data, module references

https://github.com/openscad/openscad/wiki/OEP8:-Objects-(dictionaries%3F),-Geometry-as-data,-and-Module-References
OEP8: Objects (dictionaries?), Geometry as data, and Module References

Comments solicited.

On Wednesday, September 4, 2024 at 06:22:37 AM EDT, Marcus Poller via Discuss discuss@lists.openscad.org wrote:

Acoustic or electric?

Lots of specialty shops carry wood intended for guitars.

If the wood is selected so as not to have internal stresses and appropriate grain direction/pattern, and is well-dried and seasoned it should come out as expected when cut

If the stock is properly prepared, or if one uses a suitable fixture it's pretty straight-forward.

You can trade additional machine time for smaller tool marks which will allow one to minimize sanding and use a finer grit to start.

I believe the word you want here is woodworker, but often in supporting CNC machines, folks who have zero woodworking experience, but who have metal-working experience often do quite well with cutting wood on a CNC --- once they learn to accept that the material which was once alive will still move and react and breathe and change based on humidity and so forth.

If you want to revisit it, let us know and we'll do our best to assist.

William

I don't think it needs a new use mechanism, it just needs $variables to get
the original scope back and code to track their use so that only
expressions using them need to be reevaluated when using a module. That
would massively increase performance without breaking anything.

On Thu, 5 Sept 2024 at 01:28, Jordan Brown via Discuss <
discuss@lists.openscad.org> wrote:

Where can I read this book?

No, the plastic has to hold the connector and needs to provide enough smoothness to easily insert but enough friction to not fall out. I now use a little wedge at the end to create more friction. I tried many different ways.

Make the whole hole smaller,
Make it only smaller on x or y,
Add an elastic clip that pushes on the connector,
etc.

The small wedge seems to work best and seems to work on my Ultimaker S3 in the different resolutions I tried out with Tough PLA and will use PC today because this is closer to the material in Injection Molding (IM). However, concerned how this works out with IM.

Suggestions welcome.





On Thu, Sep 5, 2024 at 10:32 AM Peter Kriens via Discuss <
discuss@lists.openscad.org> wrote:

I'm curious (I don't have experience with IM) - how much will you spend on
this mold? From what I have seen watching Youtube way too much, these will
set you back 5-figure numbers, and no do-overs - if you screw up even one
detail, congratulations, you get to do it all over. If we (well, you :) )
are indeed talking about numbers in this order of magnitude, wouldn't it
make sense for you to only prototype this using FDM, and then have someone
with experience re-make the model using software properly suited for IM
(i.e., something that doesn't create a list of triangles in 3D space)? And
then use their expertise and experience to deal with details like this
(friction fitting things is... fraught with peril, in my experience with it
in FDM), which they've (if you choose an experienced one) gone through
dozens of times already?

This is not so much a critique (as I do not have any qualifications to
critique someone who has obviously thought more about this than I did) as a
question as to why you seem to be going directly against the number one
advice given by anyone who's gone through the process you seem to be going
through, and who have bothered to do a postmortem of their process. You
must have read through these people's accounts yet have reasons to take
another route? Good luck and I'd love it if you would report back on this
list once you've completed the process and have your first products in hand.

cheers

Roel

I also came to the conclusion that the right way is to prototype with FDM and then do the extra mile to make a design optimized for IM. The high cost and long delays of the mold make this a necessity.

However, I'd like to keep the impedance between these models as small as possible because, based on the same principle, and depending on the success of the first one, I have two more down the line. I also like it because it allows me to formally capture the learning you always do in these proceses.

I am new to this world and in my naive way as a software developer I assumed that a 3D model is a 3D model. I worked in printing during the 80's and PDF was a godsend. Before PDF we had to send horribly complex instructions to the typesetters, being aware of the most intricate attributes of the type setter. PDF changed the game by creating a standard that described the perfect page regardless of resolution. You could print it on a stamp or you could print it on football field and the latter would still show perfect resolution. After PDF the typesetters took over the responsibility to print a page as close as possible to this perfect description. We could just focus on the perfect description.

Since this is 40 years ago I'd expected that a similar model was also present in the 3D world. I realize that 3D models are seriously more complicated but still it was a shock how primitive it seems.

Was a surprise ... but I've no choice but to live with this.

regards,

Peter

On 9/5/24 04:32, Peter Kriens via Discuss wrote:

Can your printer get hot enough for PC? I had to modify an Ender5Plus to
get it hot enough for PC, needs a 280C nozzle and 120C bed to Just Print
PC. Bed booster and 800 watts at 32 volts.  New hot end.  And 280C is
right at the HE ratings.

because this is closer to the material in Injection Molding (IM).

Cheers, Gene Heskett, CET.

"There are four boxes to be used in defense of liberty:
soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author, 1940)
If we desire respect for the law, we must first make the law respectable.

• Louis D. Brandeis

Peter,

some thoughts on your problems/issues:

1. "I am now working on productizing this and I decided it will need
   to be injection molded (IM)". This decision is what precipitates your
   other problems. Are you sure you need to go to IM? What sorts of
   numbers of part are you producing. If you have not seen then, I'd
   check out some of the videos on Youtube by Slant3D. They are a print
   farm in the US who are advocating the position that in many cased 3D
   printing by a print farm can replace IM. See, in particular,
   https://www.youtube.com/watch?v=lVRLuCScRdE . BTW I have no
   affiliation with Slant3D, nor have I ever used their services.

2. "To my horror I found that STEP is the standard file in the IM
   world, they genuinely hate STL files it seems." I have faced the same
   problem myself. I wanted to get PCBWay CNC some parts I have designed
   in OpenSCAD. My solution was to redesign the parts in cadquery,
   https://github.com/CadQuery/cadquery . caquery is similar to OpenSCAD
   in that it uses a scripting language (in its case Python) to design
   CAD models. The syntax and approach is different to OpenSCAD, and it
   is not too difficult to rewrite a part in cadquery, once you have got
   the hang of it. It takes a little while to learn, but I found it
   easier to learn than FreeCAD, which was another approach I tried.
   cadquery can produce STEP files. (Actually, if it were not for the
   fact that my designs rely heavily on NopSCADlib, I'd fully go over to
   using cadquery.)

3 "I recently reverted to exact measures in the source and now use
CURA to expand the polygons so they have the required size. Are there
other approach for this?" You could set a global variable "tolerance",
and adjust your code. See
https://github.com/martinbudden/BabyCube/blob/main/cadquery/FrontFace.py
for an example of a part that is produced with different kerfs for
production by either CNC milling, laser cutting or waterjet cutting.

Martin

On Thu, 5 Sept 2024 at 16:59, Peter Kriens via Discuss
discuss@lists.openscad.org wrote:

Yes.

I looked at the problem and it is not feasible for 2 reasons. First,
number that we're planning is clearly in the IM range. Second, the finish
you get with IM is necessary, it is a consumer product.

I am using the BOSL2 library and I lost any appetite to live without attach() ... I am heavily into reusable components (my life's work in software) and an important part of this is that you can easily assemble these components. It took me some time to figure out BOSL2 but it (partly) implements a model where the shape of the parent model is known in the children, which can then adapt. This is so powerful I don't want to live without it anymore. Will see what happens in CADQuery.

I already use that but my long history in software would like to create a perfect model and adjust in the next phase. Cura seems to have tuning parameters for the problem. But this might be a wrong prejudice.

Thanks for the feedback,

Peter