3D Printing - From in your head to in your hand
One of the great things about 3d printing is that you can turn something from an idea or concept to a physical item in a matter of minutes. Need a stand for your mobile phone? No problem, download a model of the internet and print it. For most common things, someone has already created a model, but sometimes you need to make something from scratch.
Whilst working on my CNC engraver, I needed a way to mount two red line lasers to mark the centre point of the milling tool. I knew how I wanted to mount the lasers but there was no off the shelf models I could use or adapt from the likes of yeggi.com or thingiverse.com.
No problem I have a 3d printer and imagination…
First things first, I sketch out what I’m thinking about. Whilst some people would dive straight into a CAD program I find it easier to sketch what I’m thinking about as I can add measurements and notes.
The laser modules are 12mm diameter and 50mm long. They need to be mounted 90 degrees apart around the 55mm spindle. My initial thought is a 3d printed collar which clamps to the spindle with a simple 3mm nut and bolt. The laser modules will just be a friction fit to allow directional adjustment,
Once I’d worked out the design and dimensions, I fired up Fusion 360 to start to create the model. Knowing that the bracket would be 3d printed I decided to make the bracket on a single plane without the needs for any printed supports. Firstly I created a 55mm circle and then a wider 61mm concentric circle. This created the 3mm wide band.
Next, the laser mounts were added using the same approach. 12mm diameter circles with 16mm concentric circles to create 2mm wide walls. These were joined to the main bracket and a 3mm fillet added to the intersections.
Finally the securing lugs were modelled by creating a 2mm gap and adding the lugs with 3mm bolt holes. As I knew I would be 3d printing this in orange PETG filament, I added the appropriate material config to the component.
One of the great features of Fusion 360 is the ability to create photo realistic renders of the models you make. I’ve sent these to customers who thought it was a photo of the final manufactured part!
At a more practical level, using a CAD program allows me to virtually assemble components to test fit and disassembly. There is nothing worse than printing a series of components only to realise they are perfect but can’t be physically assembled.
Once I’m happy with the design, it’s time to use the slicer software to create the file to send to the 3d printer.
I use a software package called Simplify3d to import the 3d model from the CAD software.
I decided that the physical component would be printed with a filament called PETG (polyethylene terephthalate glycol). PETG is commonly used in the manufacture of water bottles. It is a semi-rigid material with good impact resistance, but it has a slightly softer surface which makes it prone to wear. One of the main benefits for PETG in 3d printing is that it is less brittle than one of the other common 3d printing filaments, PLA (polylactic acid).
The print took around an hour to complete and a few minutes with a round file to clean the mounting holes for the laser modules. Next thing was a test fit on the motor spindle which worked as planned. Finally I fitted an M3 nut, bolt and washer to tighten the bracket around the spindle and job done!
