dear 3d printing voodoo masters...

[qwakers]

can someone do me a favour...

i need a waterproof switch enclosure for a water tank.

the hole for the switch needs to be 20mm. the outer diameter of the cylinder body is 35mm, the flange at the top needs to be 45mm and the entire height of the enclosure needs to be 50mm internal.

it needs to be a cylinder to insert into the hole.
see bad drawings (not to scale)...

anyone feel light printing it in white or black? something fairly durable.

 

[ajlelectronics]

I could probably deal with that.

 

[ajlelectronics]

Open bottom and flange to seal or what?
How do you intend to fix it?
What type of switch?
Flange thickness?
Cylinder wall thickness?

 

[qwakers]

these are the tough questions, for the thickness questions i would say use best judgement... 2mm? 5mm? i really don't know how thick it needs to be to make it strong enough. as long as the cavity is over 22mm (to be sure of getting the switch to lock in). itll be ok.

it will be inserted into the hole and the top flange will be glue to the plastic top of the tank
its a round waterproof momentary rocker switch that measures 20mm od. i can fettle the hole if its a bit tight.
closed bottom and i will drill a small hole for the wires to pass through then seal with silicone..

 

[daedalusminos]

it will be inserted into the hole and the top flange will be glue to the plastic top of the tank

What plastic is the tank made from and what adhesive do you intend to use?

 

[qwakers]

i would think its abs and i was going to go simple and use superglue.

 

[daedalusminos]

If it is ABS then I'd print the enclosure in ABS and solvent weld it in.

However, first thing is to verify tank material - lots of tanks are polyethylene or polypropylene and they are difficult to glue.

 

[ajlelectronics]

So this is a closed cylinder with a flange and a 20mm hole in the top? How are you going to get the switch in, or is it a snap in?

 

[qwakers]

im 99% sure its abs, but will go hunting for a little triangle to find out for sure.

aje, yes that's about it. the switch is a snap in.

 

[ajlelectronics]

Fusion file and .stl in the attached zip.

 

[ajlelectronics]

3mm top thickness in the absence of a specification. Can print in ABS so Acetone is your ideal adhesive.

 

[qwakers]

that looks great. will confirm material tomorrow

 

[ajlelectronics]

I have been pondering the printing of this. It will need supports but the issue is going to be removing the supports afterwards. Printing upside down may work with a slim tree support, otherwise it will have to have a blanking cap for the bottom, printed separately.

 

[qwakers]

If you make the blanking cap so it slides over the end in the form of a cup style lid then it can be glued on to make it waterproof. That would suit me better as if I decide it needs to be a shorter tube I can shorten it easily.

Having looked at the tank there are no recycling labels on it, however research shows me people in America have successfully glued to this tank with abs cement, so I think abs is the goto.

 

[Agroshield]

I have been pondering the printing of this. It will need supports...

Could you print right way up and have the interior overhang of the top either as an inverted funnel or as a hemispherical dome?

 

[ajlelectronics]

Could you print right way up and have the interior overhang of the top either as an inverted funnel or as a hemispherical dome?

Yes, but think about the internal support structure; how will you get it out?

 

[daedalusminos]

You shouldn't need supports - it's just a top hat, print brim to bed and the top will bridge.

 

[ajlelectronics]

You shouldn't need supports - it's just a top hat, print brim to bed and the top will bridge.

I admire your faith in a 35mm unsupported bridge! Worth a try though. I am also tweaking it for a threaded cap (an exercise for me) and a plain glue in cap.

 

[daedalusminos]

I admire your faith in a 35mm unsupported bridge! Worth a try though. I am also tweaking it for a threaded cap (an exercise for me) and a plain glue in cap.

If 35mm is too much for your printer then just taper the inside in towards the top if permitted. I always design for no supports for FDM.

 

[Agroshield]

Yes, but think about the internal support structure; how will you get it out?

I was under the impression that it could overhang by up to 45 degrees without support.

Is it possible to print an inverted funnel without supports? What is the limiting cone angle of that funnel for success?

In principle, it is the same as a corbel on brickwork. Brick domes can also be built without support.

It is not 35mm unsupported. OD is 35mm and hole is 20mm, so 7.5mm less wall thickness overhang inside.