1 Topic by Claghorn

  • Claghorn
  • Member
  • Offline
  • From: Delray Beach, FL
  • Registered: 2012-10-22
  • Posts: 730

Topic: What is with the units confusion?

Playing with various bits of software while waiting for my printer to arrive.

I finally found the openscad docs that tell me the default units are millimeters, so I designed a little logo to print that is 5 mm high and scaled it up by a factor of 5.08 to make it come out 1 inch high.

Then I export the .stl and run it through pronterface and I get all these log messages describing the print as something like 190 by 230 mm (which is lots bigger than an inch :-), so what gives here?

Let's see if I can post a link yet: http://home.comcast.net/~tomhorsley/har … oodle.html

Claghorn's Website

2 Reply by adrian (edited by adrian 2013-09-01 02:39:45)

  • adrian
  • Member
  • Offline
  • From: Canberra, Australia
  • Registered: 2013-01-15
  • Posts: 1,623

Re: What is with the units confusion?

The unit values in openscad, like most modelers, are 'unitless'... meaning they are only relevant in respect to one another within that specific model.
STL Units are also 'unitless'
When you export them, any Slic3r software or equivalent, will interpret the units as millimeters (3D printing, like the rest of the world besides the US, Liberia and Burma, use Metric Units or SI Units...)

Scaling it by 5.08 - well.. not sure what you wanted here... basically, you would be best off making them 25.4 'units' high in the first place, which converts perfectly to 1" in repetier....

So yeah.. learn to live with Metric like the rest of the world.. and just model in mm's ... then you have no issues moving between STL, OpenSCAD, Sketchup and RepetierHost/Slic3r.... with or without Units  smile

Heres the OpenScad to give you 1" high letters in Repetier Host:

// A silly little logo I can make out of my initials (T.A.H.)
// rendered in 3d. (My first openscad design :-).
//
// Tom Horsley - Aug 30, 2013
//
module tah()
{
   union() {
      translate([0,4,0]) cube([4,1,1]);
      translate([1,2,0]) cube([5,1,1]);
      translate([1,0,0]) cube([1,5,1]);
      translate([3,0,0]) cube([1,5,1]);
      translate([5,0,0]) cube([1,5,1]);
   }
}

scale([25.4,25.4,25.4]) tah();

3 Reply by Claghorn (edited by Claghorn 2013-09-01 02:59:16)

  • Claghorn
  • Member
  • Offline
  • From: Delray Beach, FL
  • Registered: 2012-10-22
  • Posts: 730

Re: What is with the units confusion?

I'm more concerned with strange log messages at the end of the pronterface log talking about "print size" and saying things about the print going from -200mm to 30mm. I don't have any idea what the heck it is trying to say there. Earlier in the log it talks about where the extrusion will start and stop and gives perfectly sane dimensions, so I don't know what the devil it is talking about at the end :-).

I've added some sample log messages to the end of my web page.

scale([25.4,25.4,25.4]) tah();

I think that will make it 5 inches high, since the whole "tah" object is already 5 mm high. The 5.08 number is the scale I need to make a 5mm object be 1 inch.

Claghorn's Website

4 Reply by adrian (edited by adrian 2013-09-01 03:02:04)

  • adrian
  • Member
  • Offline
  • From: Canberra, Australia
  • Registered: 2013-01-15
  • Posts: 1,623

Re: What is with the units confusion?

when I export the above code with 25.4 scale I get exactly 1" high letters in Netfabb and RH
When I export your unscaled model, I get 1mm high... which is why I said take the whole thing 25.4

Or export it unscaled, and scale it 25.4 in RepetierHost/Pronterface....

*shrug*

5 Reply by Claghorn

  • Claghorn
  • Member
  • Offline
  • From: Delray Beach, FL
  • Registered: 2012-10-22
  • Posts: 730

Re: What is with the units confusion?

I think I see what it going on. The dimension netfabb calls height is indeed 1 inch if you scale by 25.4, I'm afraid I was inexactly thinking of the dimension that I'd call height when viewing the printed logo with the letters upright in reading position - very fuzzy of me :-). That's the dimension netfabb calls width, so to make width 1 inch, I really do need to scale by 5.08.

Anyway, I still have no idea what pronterface is telling me with all "the print goes from" messages at the end of the log. I hope it isn't saying it is going to try to start printing with the extruder 200mm below the print bed :-).

Claghorn's Website

6 Reply by 2n2r5

  • 2n2r5
  • 2n2r5
  • Member
  • Offline
  • From: Frederick, MD
  • Registered: 2013-05-09
  • Posts: 1,208

Re: What is with the units confusion?

Why are you using pronterface? Get the RH/slic3r package from solidoodles website. Consider pronterface deprecated.

SD3 w/ mods:
Glass bed with QU-BD heat pad upgrade, threadless ballscrew w/ 8mm smooth rod, spectra line belt replacement, lawsy MK5 extruder, Lawsy replacement carriage, E3D hotend, Ramps 1.4 w/ reprap discount controller, DRV8825 drivers, 12v 30A PS, Acrylic case, Overkill Y-idlers, Filament alarm, Extruder fan + more.

2n2r5's Website

7 Reply by Claghorn

  • Claghorn
  • Member
  • Offline
  • From: Delray Beach, FL
  • Registered: 2012-10-22
  • Posts: 730

Re: What is with the units confusion?

I not using pronterface specifically, I'm using everything I can find while playing around with software and waiting for the printer, but I'm still really curious what the heck it is trying to tell me with those strange messages :-).

Claghorn's Website