Alternatives to bolts/screws

Hi, I realise that there are a number of parts that need sourcing but wondered if there might be some merit it trying to reduce this. Has anyone experimented with 3d printed methods or assembling parts instead of bolts/screws (or even a spring instead of viton bands)?

Most parts printed as one unless there is good reason not for mechanical reasons, for configuration, or for a part that may need replacing. This being said from the next version the sample riser is integrated, so that is one less part to attach.

I think reducing the number of purchased parts would be great. Perhaps by consolidating some of the screw lengths so less types are needed. In the new design I mentioned we actually increase the number of m3 nuts needed as we are trying to reduce times where the plastic threads strip ruining a part.

I am not sure what is meant by “3d printed methods or assembling parts instead of bolts/screws” do you have any examples.

As for the springs, this is something we have thought about quite a bit. The issue is that it is just as hard (if not more so) to reliably specify a spring and purchase a similar spring anywhere in the world as it is with o-rings. The exact location and mechanism with a spring is also quite hard to design. If you have any ideas we would be very happy to consider them!

Also, 3D printed springs work beautifully on day 1, but tend to very quickly lose their springiness due to “creep” in the plastic. Early designs relied on printed springs, but we quickly realised that was not reliable enough.

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I should probably state I’m not an engineer so apologies if some questions/suggestions are obviously daft!
I had been thinking of 3d printed springs but hadn’t considered the longevity. What’s the expected lifespan for the orings (have any worn out yet)?
How specific are the requirements of the spring/oring? I hadn’t thought much about non-printed springs but perhaps repurposing something fairly common e.g a small bulldog clip or biro springs?

I’ve got some ideas for reducing the use of screws, I’ll try to sketch some things, but theres likely issues I won’t have considered.

This was one idea for the fixing the motor. Increasing the size of the supporting column and adding some thin slots that the motor mount and be twisted into. Printed dowels could then be pushed into the holes to prevent the motor twisting out (or possibly a plastic rivet).

For the camera platform, adding some guide pins with the lens extension tube being held down by a pair of clips.

Could the illumination dovetail be connected to the body with a dovetail?

Those are some interesting suggestions - I could see the motor one working, though it probably comes at the cost of taking rather longer to print. The camera platform would possibly need to have the thin vertical bits printed in a different orientation, because as it is even the thicker posts have a tendency to snap depending on how well it prints.

There’s a tension here between making it maximally printable, and using a few metal fasteners for greater reliability/performance (and ease of assembly); given that we’re keen to support medical use in the future, I find we are increasingly replacing our innovative plastic solutions with nuts and bolts, because they are much more reliable. So while I think it’s a great engineering challenge to print as much of the design as we can, I think we’re unlikely to pull either of those suggestions into the main version of the project for now. I 100% agree with Julian that standardising the fasteners, so you need as few different lengths of screw as we can manage, is really helpful.

This makes sense, I don’t have a background in microscopy and am just getting to grips with the structural properties of pla. As it is, the project seems really accessible, I just seem to have a thing for simplification. If sometime in the future there might be a branch optimising cost/accessibility (perhaps aimed at education) and if I can level up my skills I’d be happy to experiment a bit. I should probably be concentrating on finishing my first microscope first!

Hi Robmc. I am not an engineer either. As a pathologist Ive been doing microscopy for patient care, research and education for over 30 years now. The last rendition of the OF scope is amazing. The quality of the images are superb and the possibilities endless. I’ve been using mine for 8 months now without a problem. However, It took me a while to learn how to print and assemble the components. Including buying a bigger printer with a larger bed. Part of the problem is that not everyone has the same 3D printer, PLA, or access to the same resources. I had to print 3 scopes until I was able to make one work the way I wanted. It is a very fun experience to build the scopes and very gratifying to see them work. I bought all my components from Amazon for less than U$S100, I will recommend you buy as many condenser lenses as you can. Those come from china and it too me 3 months to get them to the US.