GETTING TO GRIPS WITH 3D PRINTING

I've just read the article about 3D printing in the February edition, and Colin Barnett's efforts in replicating the Montego window clip. His description of the process involved corresponds well with my experience, and since our last exchange I have acquired another printer. Mine are both Flashforge, and the later one is an independent dual extruder model. They operate on the same principle as Colin's machine, but both are enclosed, so they look like microwave ovens.

As I mentioned to you, I have made many car parts for myself and others, with varying degrees of success. Owning Morris Minors means that these are the main destination for my efforts, and there seems to be plenty of scope for making parts that are not easily obtainable. I would only like to add to Colin's excellent article by saying that there is 'flexible' filament now available, and I have had some success in making some hardto-find early Minor (MM) windscreen wiper ferrules (which were originally rubber). I've made two prototypes, and found an owner in Quebec who is checking them for fit. Postal delays have inevitably extended this process!

I needed a boot stay retainer recently and found that these were currently not available, so I made my own. Most solid models are printed with internal honey-combing to reduce the volume of material used. It is normally set at 15% by default. By varying the solidity of the model, the flexibility can be increased or decreased. So if it is too soft, you can effectively increase the density to make it harder. One of my current projects is to make an improved pedestal for the SU petrol pump. This will be made with a material called ASA, which is a bit more durable than PLA (which I too use quite a lot of!). I think my version will be a little stronger than the original, with less tendency for the little pillars that retain the points to snap off. It also has a convenient slot for the 'transil' (which is the spark suppressor) to fit. It is still at the prototype stage and needs to undergo field trials in our 1957 Minor four-door.

Thank you very much for that advice, Brian. Incidentally, Colin has got in touch with the following additional comments – Ed

Since writing my feature on 3D printing, I’ve been getting to grips with another material which could have widespread applications for classic car owners. Traditionally, filaments to manufacture flexible components have been limited to use in more expensive direct feed printers as pushing a compressible filament along the 300mm tube between the extruder feed and the hot end of an entry-level printer should result in a poorly controlled feed onto the model. However, TPU (thermoplastic polyurethane), which is becoming widely available in a range of colours at an affordable cost, produces items which have similar qualities to rubber, even on my budget Creality Ender 3 machine. While I’ve yet to create any automotive components, my tests show its suitability for items such as bonnet stay retainers, buffers and vibration insulators, but I probably wouldn’t advise it for anything safety critical such as hydraulic seals! If you have a 3D printer, I strongly recommend you give TPU a try.

Colin Barnett