Imagine for a second it’s the mid-1980s and you’re looking in to desktop publishing setups. Those new LaserJets and LaserWriters are pretty cool, but imagine the desktop publishing world if you couldn’t create your own documents. Yes, it seems absurd to have a printing press that won’t create unique documents.
Now flash forward 30 years to the world of desktop manufacturing and rapid prototyping. There are dozens of repositories for 3D printable objects, but making something of your own design is apparently a dark art and arcane knowledge to everyone buying 3D printers for plastic octopodes and bottle openers.
This week, by popular demand, we’re going to be making a ‘thing’ in SketchUp Make. It’s free, easy, and surprisingly versatile despite its limited tool set. Common sense and Google algorithms dictate I link to previous tutorials in this series below:
And now on with the show. You’re gonna want to click the ‘read more’ link.
As with all of these Making A Thing tutorials, we’ll be using this switch base to the right. Click to embiggen.
Last week brought some interesting observations of this thing thanks to a few readers. I shan’t bore you with that now, but I have added a few notes regarding this thing at the bottom of this post.
Setting Things Up
There are two version of SketchUp; SketchUp Pro costs about $600. SketchUp Make is freeware and more than capable of building any mechanical part you can imagine.
After installing and launching SketchUp Make, you’ll be asked to choose a template. We can use the “Product Design and Woodworking” template. Amazingly, the folks at SketchUp were kind enough to give us an option between using inches and millimeters. Since our ‘thing’ is in inches, select that template and hit ‘Start using SketchUp.’
Beginning Our Thing
The basic idea behind Sketchup is the ability to draw in two dimensions and use the Push/Pull tool to extrude a shape into the Z axis (or in SketchUp’s case, the blue axis). On the toolbar at the top of the window, select the Circle tool. Click on any point near the intersection of the red, green, and blue lines.
If you followed along with the AutoCAD tutorial, making this circle the required size will seem very familiar. To get a circle with a diameter of 2 3/8″, just enter the radius on your keyboard’s keypad. That’s 1 3/16″ for those of you not in the USA, Liberia, or Myanmar.
Our first order of business is making the 3/8″ slot in the ‘big circley part’ of our thing, and drilling out the center. We’ll start with the slot first.
SketchUp has a great snap-to function that we’re about to try out. On the toolbar, grab the pencil or ‘line’ tool. Wave that around the center of the circle and eventually it will snap on the center. Click the center and draw a 3/16″ long line (remember you can enter the measurement on your numpad) along the red axis. Click the center again and draw another line, same length, in the opposite direction. From the ends of these lines, draw straight down, making the slot in our part. Next, pick up the eraser tool. Erase the little bit of the circle’s perimeter between the slot we just drew.
Now for the hole. Select the circle tool, hover over what you think is the center of the big circle and wait for it to snap. Draw a circle with a radius of 1/2″. With the eraser tool and judicious use of the delete key on your keyboard, you’ll have something that looks much like our thing. The only thing left to do is rotate it.
From the Tools menu, select Rotate (or just use the ‘Q’ hotkey). pick a point on the purple area of our part and pick a second point along the green or red axes. Depending on where you clicked you’ll need to enter either 45, 135, 225. or 315 degrees on your keypad.
Now that the slot is all lined up properly on a 45 degree angle, we can start work on the two little flanges coming off the round part of our thing. The wider flange – except for the fillets on the corners – are left as an exercise to the reader. The same goes with the other side of the part, except for this one little ‘gotcha’ in the design, seen to the right.
If we extend the side of this flange down, it doesn’t intersect at the end of our slot. No worries, really. Just draw the line how you normally would, click on the inside of our slot, and try to ‘extend the line. SketchUp’s snap to is great, and you’ll easily be able to draw a line where you want it. After that, clean it up with the eraser.
We need to round over four corners on our thing, all of them on our big, wide flange thingy sticking out of the bottom of our part. First we’ll do the outside corners.
We need a 1/8″ radius on each of these corners. Start by drawing two 1/4″ lines along the sides of our thing. In the .gif above, I added two hash marks where the lines ended. Draw a line between these two endpoints, then draw a 1/8″ radius circle at the midpoint of the hypotenuse of this triangle. Clean up with the eraser and do the same on the other side.
The inside corner is a bit more tricky. If we were using AutoCAD, we would just use the FILLET command to make a perfect fillet on the inside corner. SketchUp isn’t as advanced as AutoCAD, but we can fake it with what we have.
SketchUp has a tool called Offset (hotkey ‘F’) that allows you to ‘trace around’ any object and specify the distance between lines. If we offset a few lines 1/8″ away from our part, wherever they cross is where the center of our 1/8″ fillet should go. Once we know where the center of our fillet is, we can just draw a circle and get a perfect radius on that inside corner. Pretty slick, huh?
Here’s what we end up with, sans the eraser tool:
Now it’s time to work on the ‘tall’ part of our thing. Off the small flange, draw a 1/2″ x 1 1/2″ rectangle. With the Push/Pull tool, extrude this rectangle up to the center of the through hole, or 1 5/16″ (that’s 7/16″ for the thickness of the base, and another 7/8″ beyond that).
Now, use the circle tool and hover over the midpoint on the top front side of our new 3D solid. Create a circle the width of the rectangle and extrude it backwards half an inch.
Using the same process, you can easily create the drill hole and counterbore on the part. It’s very easy, just use the Push/Pull tool and the eraser.
Wow. Such Thing. Much Dimensions.
There you go. A thing made in SketchUp. All that’s left is to send this model over to your 3D printer. SketchUp doesn’t support exporting to .STL files, though, but that’s a post for the end of this ‘Making A Thing’ series.
That’s it for this installment of Making A Thing, but I would like to say a few things about the part we just made.
Just like the other Making A Thing tutorials, our ‘thing’ is taken out of an 85-year-old drafting textbook, Engineering Drawing (French, 1929). This is the fourth edition of this book and last week I asked if anyone had a first edition (from 1919). [Jacob] is awesome and found a first edition, but this part isn’t in it.
Also, for the first time ever, someone noticed these parts I’ve been making have been terribly wrong. Look at the width of the thinner flange. It’s one and a half inches across. Now look at the radius of the ‘dome’ on the tall part. That’s 5/8″ radius, or 10/8″ in diameter. Twelve eighths is not equal to ten eighths. That tall part actually has a taper.
In my defense, I would have found that taper if I did the assignment – making a three view drawing – for this part.
Despite these tutorials being seen by tens of thousands of people, [tarasbot] was the only one to pick up on this. He emailed me and now he’s getting a Hackaday t-shirt, some stickers, and whatever swag I can scoop up after the Hackaday party next week. Gonna need your shirt size, [tarasbot].
That’s it for now, next week is Autodesk 123D, and as always your suggestions for what softwares to build a ‘thing’ in are always welcome.