I have a 10 x 10cm square plate of metal I would like to insert into a hole in the wall of plastic water tank (cube shape), I'm planning on 3D printing the tank itself (only 1-2 litres).

What would be the best design to stop water from leaking between the plate and the plastic body?

So far all I can think of is to make the hole in the tank smaller (i.e. 8 x 8cm) than the metal sheet and perhaps using a sealant and affix it using screws possibly, but as there's live wiring around it I need to be sure it has the best possible seal. Any design ideas would be much appreciated


2 Answers 2


A common way to do this is to use mechanical fixings (bolts, rivets etc) and a flexible or semi-flexible gasket to provide sealing.

Here the mechanical fasteners physically hold the plate on and also compresses the gasket between the two materials to form a good seal.

Bolts are ideal for this as they allow quite fine adjustment of the clamping force so that you can get even pressure around the seal. If the tank material is relatively flexible it may also help to sandwich it between two plates to event and warping of the joint, although the second plate can be reduced to a frame or collar. If the tank is more or less as rigid as the plate washers may be adequate. Of course if you are 3D printing it you also have the option to thicken the material around the hole. you may also want a bit of extra material to allow you to grind/sand it flat to get a flat, smooth mating surface.

There are a variety of gasket materials including sheet, O-rings and compounds which can be applied as a paste, putty or liquid. For example neoprene sheet is fairly commonly used for water tank fittings.

  • $\begingroup$ Thanks for the informative reply. Do you think something along the lines of this: slip-not.co.uk/size/Solid-Neoprene-Rubber-Strip/… I could probably cut it to size myself? $\endgroup$
    – Hotjam
    Apr 26, 2017 at 15:58
  • 1
    $\begingroup$ Ideally you would want to cut it from a sheet about the same size as the plate to avoid any joints, you can bond neoprene together but it is an extra layer of complication. Any h oles are best made with a wad punch, including putting a radius on the corners of any cut-outs to prevent nicks which can start tears. Alternatively a liquid gasket compound is a convenient solution for on-off jobs as you apply it as a viscous fluid and cures to a rubbery compound. $\endgroup$ Apr 26, 2017 at 16:05

It sounds like you just need a small liner on the plate itself. Foam sealants are typically used when the space that needs sealing is greater than 1/4inch. For smaller spaces, waterproof caulking may be used instead. Just Do not allow the foam sealant to come into contact with skin; it adheres to the skin and can pull off the top layer of the epidermis when removal is attempted.

Other quick and easy temporary measures for stopping pipe leaks include wrapping waterproof tape over the bad spot or rubbing the hole with a stick of special compound. Applying epoxy paste or inserting a self-tapping plug into the hole are other alternatives. When using waterproof tape, be sure to dry the pipe thoroughly before you start wrapping.

Here's an interesting site I found about the topic too: https://haynes.com/en-us/tips-tutorials/how-trace-interior-water-leaks-your-car


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