It’s time once again for another installment of a Making A Thing tutorial, where I design the same part, over and over again, in multiple 3D design software packages.
Last week we took a look at FreeCAD, a free, open source parametric modeller. It’s an amazingly powerful tool, and not it’s finally time to complete our model of a strange object ripped from the pages of an 80-year-old drafting textbook.
Here’s some links to previous Making A Thing tutorials, doe:
- AutoCAD Part I
- AutoCAD Part II
- Blender Part I
- Blender Part II
- Autodesk 123D
- FreeCAD Part I
Read on for the second part of our FreeCAD tutorial
Our Thing, And Where We Left Off Last Time
To the right is the thing we’re making. It’s from an 80-year-old book on drafting.
A few people have asked me for a .PDF of this book. My copy is in dead tree format, and I haven’t yet built a book scanner.
If anyone out there has the 1st or 2nd edition of Engineering Drawing (French, 1911 or 1918), please scan it (its public domain) and post a link. Here’s the Google Scanned copy of the 2nd edition.
In the last installment of this tutorial, we went over installing FreeCAD, the basics of parametric modelling, and drawing a few circles and lines. Finishing off our ‘thing’ is just a process of drawing lines, arcs, and fillets, constraining them, and tearing your hair out at the inability of FreeCAD to show you the one unconstrained element in your sketch oh my god. After a little trial and error, we end up with something like the pic below, a fully constrained sketch of most of our switch base:
Yes, it’s ugly, but it’s accurate. Now it’s time to move on to the third dimension, extruding our thing up 7/16th of an inch. Note that I really don’t care about the absolute dimensions of what I’m designing. FreeCAD is metric only, so I’m designing everything around eigths of an inch. Slicers allow you to scale a print anyway…
Once we have our part drawn and constrained, the Solver on the left hand toolbar will tell us we have a fully constrained sketch. Now it’s time to extrude our object. Click Close on the Tasks bar, and you’ll end up with a few options: Create Sketch, Pad, Pocket, Revolution, and Groove. The tool we use for extrusion is Pad, so click on that. Switch over to the isometric view, set the pad parameters for the correct depth of extrusion, and you’ll get an awesome filled solid. Awesome.
While we couldn’t do the ‘interior’ fillets on our part in the Part Design workbench – the fillet command only works between two lines, not a line and an arc. Now that we’ve extruded our thing into the Z axis, we can finally add those fillets. In the 3D view, click the edge separating the big ‘washer’ of our part and the long flange.
After that, we get a fairly good-looking part. We’re not done, though. We still need to make the other part of our thing, the ‘countersunk flange’, as I like to call it.
Adding Another Part
Right now we have the ‘bottom’ of our thing designed, but we’re still missing the flange with the countersunk hole. To add this, we’ll need to create the outline of the ‘countersunk flange’ part of our thing. Do that by going int the Part Design workbench, drawing a fully constrained part, and extruding it just like we did with the first part. When we’re done, we’ll have something that looks like this:
With that done, it’s time to assemble these two parts. When we go back to the Part workbench, we’ll see something like the pic to the right. Our parts are there, but we’ll need to arrange them correctly and join them somehow. After that, we’ll need to put the holes in our flange. Easy enough.
Arranging The Parts
In the Part workbench, select the flange you just made in the part tree for our thing. There’s a tab at the bottom labeled ‘Data’, and this is where we’ll place our flange at the end of the ‘washer’ part of our thing. Play around with the position until everything’s correct, and we have 90% of our thing done.
Adding The Holes
Select the face on the flange we want to drill our holes into. We’ll need to create two sketches for this; one for the through hole, and a second for the counterbored hole. Sketch the smaller hole, then remove it with the Pocket tool. This tool is pretty much the opposite of the Pad tool; it extrudes “down” instead of “up”.
In another sketch in the face of the flange, draw the larger hole, and Pocket it down to the proper depth.
And there’s a completed part. Export, do some Booleans if you need to, and we’re done.
Wrapping Up FreeCAD
FreeCAD is an amazingly powerful tool, but in making this tutorial I did notice a little bit of wonkiness in the FreeCAD interface; using the middle mouse button to pan the sketch through the current view didn’t always work, adding a line sometimes (though rarely) results in freezes, and there were a few instances where the UX is just… crummy.
Seeing as how FreeCAD is currently in version 0.13, and possibly the fact that I’m using the Windows version, this sort of thing is to be expected. It’s still being improved, and although I believe FreeCAD will eventually become one of the best open source design and modeling softwares out there, it still needs a bit of work.
If you know Python and C++, and you’re looking for an open source project to contribute to, I’d highly suggest helping out the FreeCAD devs. There’s no doubt in my mind FreeCAD will eventually be as popular for mechanical and 3D design as KiCAD is for electronic design in a few years. FreeCAD is still a great package now, but it needs a little bit of work before going mainstream.
That’s it for this Making A Thing tutorial. Next week Hackaday contributor [Rich] will putting up the first part of a tutorial on Solidworks. It’s awesome, and you’ll read it.
After the Soildworks tutorial, I have absolutely no idea where these Making A Thing tutorials are going to go. Between the half-dozen software packages this series has covered so far, We’ve covered just about every method of creating an object to be 3D printed – AutoCAD for traditional drafting, FreeCAD for parametric modeling, and OpenSCAD for scripting 3D modeling.
Writing more tutorials for other software packages would only duplicate what this series already has done with less popular softwares. This means I’m sort of in a bind as to what to write next for these Making A Thing tutorials.
If you have an idea of what this series of tutorial should do next, drop a note in the comments. I’ve also considered getting a Printrbot Simple and showing all the ways a print can fail – and the ways to fix it. If you have a better idea, you’re always able to suggest something in the comments.