How to loch things in place?

[mossy pasture]

How could I make something to lock a small opening? I'll make a test tube holder, but I would want some way to lock them in place without completely covering the front of the tube. How could I implement this in my design?

[twilit ember]

AI Help

You could design a small latch mechanism that securely holds the test tubes in place without obstructing the opening entirely. Consider creating a sliding or hinged latch that can be easily manipulated to secure the test tubes. This design would allow for easy access to the contents of the test tubes while keeping them securely in place when needed. Experiment with different latch designs to find one that best fits your needs.

WARNING: This response is AI generated and may contain errors.

[sacred quail]

Try using a dovetail joint, if applicable. Do you have any pictures of the model?

[vestal mauve]

Friction fit? Commercial, injection molded holders sometimes use small tabs in the tube holders to "clamp" against the tubes. You would need some material that can withstand a lot of bending. Polypropylene for example. Also good for its chemical resistance. If its for a bio lab I would advise against 3d printing though. Autoclaving might be too much for it.

[mossy pasture]

It's doesn't have to be autoclaved and it also won't contain chemicals. It'll be used to study animal response to certain physical factors. Would PLA be okay to use for this?

[mossy pasture]

I just need a mechanism that prevents the tubes from slipping out because of vibrations, but I still want to be able to quite easily take them out for observation

[vestal mauve]

Pla will not hold up to bending forces. The easiest would be to have an opening for the tubes thats already snug and then using a bit ot clear tape around the neck of the tube to "fill the gap"

[mossy pasture]

How big should the gap between the tube and the holder be to get such a snug fit?

[vestal mauve]

Best to print a small test piece to gauge how much bigger you have to design the hole

Glass or plastic tubes?

@mossy pasture

[mossy pasture]

Probably plastic

What's the difference if I would use glass?

[vestal mauve]

Well you cant jam glass quite as hard into a plastic part without it breaking. Especially thin test tube glass

If you remind me in about 12h I can send you a picture from my work with what I mean

[mossy pasture]

I'll try to remember

[vestal mauve]

Me too

[mossy pasture]

I also have another question: How thick should the sides be?

[vestal mauve]

Basically like this, blue is the tube

[mossy pasture]

Oh okay i understand

Unfortunately I won't be able to use it for this project as I have to block out all light

[vestal mauve]

4 walls at 0.4 mm would be my suggestion

[vestal mauve]

Aluminium foil around the tube is what we do for our light sensitive stuff

[mossy pasture]

Is it still as easy to push into that design you drew?

But it does indeed save a lot of filament

[vestal mauve]

Should be but then you can also just use the snug fitting hole idea

[mossy pasture]

true

[vestal mauve]

But the bendy tabs I drew wont work good with pla

[mossy pasture]

What's the best way to design this? I'm very new to 3D modelling and am still trying to figure things out. Do I use a few circular supports that go all around the tube of about 1cm wide?

[vestal mauve]

Give me a some time I show you what I printed for our lab

[mossy pasture]

Okay, thank you for helping me

This what I've been able to make so far

It still uses way too much filament. But at least I managed to make something that could work

[vestal mauve]

Photo was for the line on the side

But what you drew is basically right

Just give it speedholes and use alu foil/tape for the tube itself

Also thats for 1 mL glass vials so not really comparable in size

[mossy pasture]

Is there an easy way to add them? How do I know what size of holes I need so it doesn't break too easily?

[vestal mauve]

Hard to say, really.

[twilit ember]

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[mossy pasture]

@vestal mauve It's been about 12h since you asked me to remind you to send the pictures of the setup you use for the test tubes.

[vestal mauve]

on my way to take a picture

[vestal mauve]

may take some more time since, you know, work 😄

[mossy pasture]

Take your time

[twilit ember]

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[vestal mauve]

Sorry. None to be found. We might put these into storage.

But these are just three plastic grids, two with square holes for the tubes stacked on top of each other and a finer gridded one for the bottom. The squares have small, thin tabs in the corners that center and "clamp" the tubes.

Similar to what I have drawn yesterday

[twilit ember]

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[mossy pasture]

I have made a model for this and will try printing it for the first time soon. I don't know what kind of filament I should use. Could you help me with this @vestal mauve? It should be able to resist 2°C-40°C and it should be able to easily support 10 of these stacked on top to make a block of 100 test tubes.

[vestal mauve]

Nice

I printed all the lab stuff in PETG

[mossy pasture]

The real temperatures it might get subjected to should be 5°C-37°C, but it's better to have some room for error

[vestal mauve]

Except for one thing which they broke so I did it in TPU

[vestal mauve]

You might want to use hexagons for the sideways holes, otherwise you will get very ugly overhangs in the middle

[mossy pasture]

So this should be able to resiste the temperature range and be strong enough to support the tubes? It doesn't have to be that elastic as the setup should stay in place most of the time. The tubes have to sit in there, but they don't have to be stuck too firmly

[vestal mauve]

Yeah petg will be fine

Petg goes to 70ºC safely

[mossy pasture]

I was going to print it with the test tubes facing upwards (of course not with the test tubes inside) as the back plate is easier to print that way

Does the orientation of the hexagons matter?

And do I just use the diameter of the circles as the distance between two corners?

[vestal mauve]

Pointy bit up if you use hexagons, cuts way down on overhangs compared to circles.

And the diameter so that the edges of the hexagon are tangetial, not the corners

[mossy pasture]

Do you know how I can find out the amount of filament a model will use to be able to estimate the costs?

[vestal mauve]

In the slicer

[mossy pasture]

Doesn't that leave to little space inbetween the individual hexagons? Or do I just love them apart if that happens?

[vestal mauve]

If you used the holes to save filament it probably will be disappointed

[vestal mauve]

yeah that could happen

[mossy pasture]

That is indeed what I use them for

Are there better solutions without sacrificing rigidity too much?

[vestal mauve]

Adding all the holes adds a lot of outer walls so your filament use is only marginally less or even more

Straight walls no cutouts

Saves printing time too