Introduction: 3D Printing Holders for Odd Shapes
It seems I'm always running across some item just crying out for some organization, but whose shape is odd enough that it's not easy to model for a holder or case. And, they are usually uncommon enough that a 3D model is not available on Grabcad or other libraries. 3D scanning them is big leap since the time invested in getting a model is likely overkill for the holder I want.
I ran into this recently when I wanted to organize my chisels in a magnetic holder along side my hand planes.
The solution is a photograph taken from 20 feet away, Fusion 360, and a 3D printer.
Step 1: Take a Picture From a Long Way Away
To get a good outline of the item, in my case the chisel handle, you need a picture. But, that picture take from 2 feet away is no good; there is way too much parallax to give an accurate outline. Rather, I take my SLR with a 200mm telephoto lense, set the chisel on the floor and take a picture straight down from the top of the stairwell. The further away it is, the better (thus the telephoto lense), but I get very good results from 15 feet away. The goal is to minimize the perspective angle as much as possible.
Step 2: Import Into Fusion 360 and Scale
Now you can import the picture into Fusion 360 as a Canvas. Select Insert -> Canvas and put the picture on one of the major axes.
It will be the wrong size, but Fusion 360 has a great feature that allows you to define two points on the picture and specify the actual distance they should be apart. This is the "Calibrate" command. Carefully measure the actual item. Choose a long measurement, not a short one, to minimize error (I chose the length of the handle from base to chisel shaft). Right click on the picture of the item in the "Canvas" group and select "Calibrate". Then select the two points on the picture and enter the value you measured.
This will give you a picture that is "actual size" at least in Fusion 360 coordinates, which is all we care about here.
Step 3: Trace the Outline
With the calibrated picture, you can now create a sketch on the same plane as the canvas and use the drawing tools to trace an outline of the object. In my case I used a combination of arcs and splines to follow the exterior contour of the chisel handle on one side. With an axis drawn down the center of handle I now had a profile of the tool handle. Make sure the profile is closed so that you can select the entire region.
But, before moving on, consider the fact that this will undoubtedly be a very tight fit. You will need to add some clearance to the profile so the tool will actually drop in the hole and not get hung up. For this chisel, I added 0.5mm to the profile. You can do this by invoking Modify -> Offset from the menu and then selecting the profile edges.
Step 4: Make the 3D Model
Since I want a holder for the chisel and not the chisel itself, I now need to cut the profile out of a base shape so the chisel handle can drop in. Start with a basic shape for the holder. In the case of the chisels, I have 4 of them and wanted them to fit side by side. I extruded a shape 20mm thick below the sketch profile, and large enough to accommodate all 4 chisels.
Now, make the first cutout in this surface using the Create -> Revolve command and sweep the profile through 180 degrees. This gives the first cutout.
Use the Create -> Pattern command to array that feature 3 more times with the desired separation between each handle.
Step 5: Print and Use
Then it's simply printing the holder and using it.
I've used this technique on chisels, squares, taps and dies, tap handles, pistols for gun cases, battery cases, and also to recreate broken handles and brackets without resorting to laborious measurements and re-engineering.