So you have a 3D printer and need to print something of your own design. That’s a problem if you don’t know how to create and edit 3D objects. In this post, we’re continuing our previous misadventures with Blender by making a ‘thing’ torn from a very old book on drafting.
Previously, we’ve made the same part in other 3D design packages. Here’s some links to those other ‘Making a Thing’ posts:
We’ve already done half the work to make a ‘thing’ in Blender, so now it’s time to finish the job. Check out the rest of the tutorial below.
To the right is the ‘thing’ we’re making for all these 3D Printering tutorials. It’s taken out of the 4th edition of Engineering Drawing (French, 1929, p. 105). Yep, it’s an 85-year-old drawing with fractional inches. It serves our purpose, though: a template with which to make something with a 3D CAD package.
By the way, if anyone out there has a 1st edition of Engineering Drawing, I’d love to see if this object actually goes all the way back to the 1911 volume.
The Curse of Blender & What We’ve Done So Far
In the first part of this tutorial, I said using Blender to create a simple mechanical object like our ‘thing’ is akin to using a bulldozer to build a sandcastle. I’m still standing by that assessment. If you want to make precise mechanical parts, don’t use Blender. Blender is a tool for organic and sculptural forms. Want to print out a plastic tree? Blender is a great tool. Want to model some Greek and Roman statuaries? Blender is a great tool. Need a part for a mechanical device? Don’t use Blender. It’s not the right tool for the job.
In the first part of this tutorial, we took a look at the idea behind Blender – mesh editing – and how to interact with vertices, edges, and faces to make a thing. With all the introductory stuff out of the way, it’s time to finish the job.
More Building Of A Thing
To the right is where we left off with the last part of this tutorial. It’s basically just a washer, but the dimensions are correct for the thing we’re making. There are a few things we need to do before this ‘thing’ is done though:
- Add the 3/8″ slot on this washer
- Add the 2 3/4″ wide flange thingy
- Add the 1 1/2″ wide flange
- Build the mounting bracket with the countersunk hole
Not too bad, and we can do these piecemeal.
Adding the 3/8″ Slot
The first order of business is going into object mode and creating a cube with Add -> Mesh -> Cube on the top menu. With the rotate and scale commands on the right hand toolbar, manually set your cube to be 3/8″ in the X and Y axes, and 7/16″ in the Z axis. Then rotate it 45 degrees around the Z axis. You should end up with something like the pic to the left.
By this point you should have two objects in your top right hand toolbar: A cube and a cylinder. Now we’re going to subtract the cube from the cylinder using a modifier.
In Blender, you can do Boolean operations like Union, Subtract, and Intersect. There are, however, a few limitations. Each Boolean operation only divides up faces and edges, meaning you need to go in and manually delete all the extraneous edges after the operation. Also, the Subtract operation doesn’t put in the missing faces we’ll see once we subtract out the cube.
Subtract the cube from our cylinder. After deleting a whole bunch of faces and edges, and creating the ‘inside’ of our 3/8″ slot, we get something that looks like this:
Adding The Flanges
Our thing has two flanges coming off the ‘washer with the slot’ we just made. To create the flange that’s 2 3/4″ wide, Add a cube mesh in object mode and play around with the Scale (hotkey ‘S’) and translate tools. The left hand toolbar will allow you to move and scale this cube into something resembling the larger flange on our ‘thing’. After that it’s a simple matter of doing another Boolean operation (this time ‘Union’) and making something that looks something like this:
That looks just about right for the first flange, but we’re missing the radii on a few corners. That’s not a problem, though, because the Bevel tool exists.
In Edit mode, select one of the outside corners of our new flange. Hit CTRL-B and you’ll be able to set the radius of the bevel with your mouse and the number of segments of the bevel with the scroll wheel. No, you can’t specify a radius, which is just a tiny part of what makes Blender terrible for mechanical design.
Now, extrude two faces of our cylinder out (we’ve completely given up on dimensional accuracy, if you haven’t noticed), and bevel two edges on your new extrusion. In the end you should have something that looks like this:
That’s close enough to the orthographic drawing of our ‘thing’. Yes, there are holes in the mesh but we can fix those later.
The other flange is easily constructed in the same manner as the first.
Putting that dome and counterbore in
The last bit of our ‘thing’ to build is the weird rounded part with the hole and counterbore up top. Start by extruding our second flange up the necessary amount. Next, create a cylinder in object mode and Boolean-ing the two together. After deleting the faces on the cylinder, you’ll end up with something like this:
There’s one thing left to do: put a 7/16″ hole through the faces we just deleted, and put a 7/8″ counterbore on that hole. Basically, we’re making another torus/washer-type object. Check out the first part of this Blender tutorial for instructions on how to do that.
Finishing off the second cylinder/counterbore, we could call this part somewhat complete. Here’s what we ended up with:
This isn’t to say this part is ready to head over to a printer, though: there are still a few holes in our mesh which will crash any slicing program. This can be fixed with MeshLab, but that’s a tutorial for another time.
Well that’s over with.
That’s how you make a ‘thing’ in Blender. It’s not pretty, but you can do it. Once again, I need to reiterate that Blender was the wrong tool for this job. If you’re making objects to put in a video game, Blender is a great tool. If you’re doing something that could be considered digital sculpture, Blender is a great tool. If you’re making something with straight lines, dimensional parts, and precise angles, you can do far better with one of a hundred different CAD packages.
Concerning next week’s tutorial, it’s a tossup between Solidworks or Sketchup. If you have a preference one way or another (or even a third option), leave a note in the comments.