Plate and film Cameras
Plate and film Cameras
Battersea Power Station 1955
Battersea Power Station 1955
Battersea Power Station 1955
Cars
Cars
Battersea Power Station 1955
3D Printing
3D Printing
3D Printing
Geological Museum 1975
Geological Museum 1975
Adrian's Memories
3D Printing
There are 2 main types. One uses a bath of fluid and a laser that hardens it to make solids, the other melts a plastic and squeezes it out of a moving orifice to build up the print - this is the type discussed here
3D printing is probably the most fascinating development in my lifetime apart from the transister. All my life I have made things, in the early days just with a saw a vice and a hammer. Later , in my late teens, I bought a lathe and when I started self employment I bought a mill and sheet metalwork bending and cutting equipment.
I must have spent thousands of hours constructing mechanical contrivances for clients, both for scientific and museum display purposes. And when you have made one and need a second you start again and it takes twice as long. Every bit of the work needs concentration to keep to the exact specification and tolerences. Drawings have to be made and filed away afterwards in case another is required later.
Now this all still exists but for many small items like boxes, brackets, enclosures, washers, spacers and the like can be made in a fraction of the time, and once designed they can be turned out all exactly the same with no mental effort or personal time.
I came into 3D printing just a few years ago when sadly most of my time making things was over. Now I was redeveloping the Geotek goephysical instrument as many of the components were no longer available and considerable redesign had to be done. One of the first jobs was to redesign the mechanical head assembly which up to now had been made on a CNC machine with the coil formers turned on a CNC lathe. Mechanical precision with these parts is the most important factor and I was delighted with the repeatable precision 3D printing achieved.
Printing in ABS I was able to make the coil formers, now in 2 parts welded together. it was possible to produce a tiny hole 0.5 x 0.5 mm through material 3 mm thick for the wires to pass through, and furthermore right up against the end flange which would be impossible with any other construction process other than moulding.
The other upgrade was to mount the head coils at an angle facing to the same spot in the core sample to, it was hoped, give better readings.
This photo is of part of the coil assembly. The core diameter is 10 mm to give you an idea of the resolution.
The 3D printed head block takes 2 angled coils. They are rotatable with hex shaped ends rotated by a 3D printed spanner. This block took over 5 hours to print.
About 3D printers
The 3D printer market is a nightmare with so many models and all at a wide range of prices. Being a newcomer it was easy to suffer 'mental indigestion' from everything I read.
At the Model Engineer Exhibition I met a man on the SMEE stand who had some wonderful samples of things he had made with his printer. He said 'this is the only printer worth buying' so I bought one - an Ultimaker 2+extended. That was 3 years ago in 2016.
(SMEE = Society of Model and Experimental Engineers)
It has an amazing maximum resolution of 20 microns - less than 1 thousandth of an inch, and a range of 4 nozzle sizes from 0.25 to 0.9 mm. The above coil former was printed with a 0.4 mm nozzle at 0.15 mm layer height (6 thou of an inch). Nowhere near its maximum resolution.
The main drawback to 3D printing is the time it takes to print the item. The coil above probably took well over an hour to print both parts.
The slicing software is used to convert the drawing of the 3D model into a file the printer understands and is critical to the result. The Ultimaker software is called CURA and is constantly being updated and improved. It is now superb. You can now set wall thickness and infill density to any amount and for any layer height or nozzle size. Much improved since I started using it 3 years ago.
Printed flanged ring over nut on my adjustable vice to save using a spanner to adjust
Pound sized token for supermarket trolleys. Printed at low resolution and given away in our Avensys superstore
Typical box to house components. Designed in 15 minutes and printed within the hour whilst you have lunch
This is about generating the 3D drawing
Now to the problem of generating the the object you want to print. A 3D CAD program is required to make the artwork that you print. There are many options, both free and some really expensive, costing thousands of pounds a year. Some are good for faces and figures and others for more mechanical designs.
Most CAD programs require you to design a shape in 2D or flat mode then to 'pull' it out to make a 3D object, and can produce superb and very detailed results. Autocad, Design Spark and Fusion360 work in this way. However, in my advancing years there is so much to learn about the protocol (doing things in the right order) that I found it a dreadful uphill struggle to remember what I had done the day before and the learning curve started again.
I have tried many free programs and have settled on one called Tinkercad by Autodesk. It was originally written by a Finnish company bought up by Autodesk around 4 years ago.
Autodesk have improved it greatly and now it is really superb and quite easy to learn.
Unlike the others you work in 3D and build up your object by manipulating 'blocks'.
There are many standard shapes to start with which you can resize, group or position in any way. They can be joined together in any plane. They can also be set as 'voids' (holes).
Thus to make a box you create a block the overall size of the outside. you then create another block the size and shape of the inside, and set it to be a void. Then you align the 2 items (very easy to do a precision align) and group then. Hey Presto you have your box.
Precision dimensions and placements are easy and any surface can be set as the groundplane to work from and any dimension can be set to 1/100th of a millimeter
Drawbacks. In other programs your work is listed in a 'timeline' and you can go to any point to make changes which is very useful. In Tinkercad you can only go backwards from your current point which can be a major problem. The answer is to plan your work ahead so any uncertainties are the last operations you do. Also if you make a change and save your work with a new name it overwrites the previous design which is lost forever. So simple to avoid. You simply copy the design, or part of it, and paste it in to a new design so you now have both saved. So a complicated project can be broken down into several parts which can be copied and pasted into the final drawing.
Radio Club project. An antenna analyser housed in a 3D printed case. I made over 15 of these for club members
This is about 3D printing materials
We are talking about FDM printing where a filament of plastic material is squeezed out of a nozzle in molten state by a moving print head that deposits it on the print bed. The first choice is 'PLA'. It is biodegradable and made from organic material, most machines can use it. It does vary, some makes are very brittle but others much stronger and slightly flexible.
One problem is that it is difficult to glue, even with Araldite you have to roughen up the surfaces to key the joint
The other material I have used is ABS which is derived from oil. It works at a much higher temperature and is very strong. Printed holes can easily be tapped and it is easy to weld parts together with acetone. For best results the print temperature must be exact (235°C on my machine)
There are many other materials, and more coming on the market every day so I won't list them here.
Print adhesion to the print bed. My printer has a heated glass bed. Before printing I give it a light spray with 'DIMAFIX'. An amazing material that the print sticks to when hot. When it cools the print can be easily lifted off - as if by magic.