Manufacture homemade centrifugal water pump

Me propuse hacer una bomba de agua centrífuga casera, y aquí tienes el resultado.

Submersible water pumps as a general rule, have little power.
If you want to use a submersible pump outside, you have to make a watertight body so that the pump can move the water.
And in short, it is the least suitable for recirculating water.

There are pumps online, that is, non-submersible, and reasonably priced, although they may not be within your reach.
However, most in-line pumps are not prepared to work with hot water.
Some in-line pumps work very well at first, but will break down after a short time.

In-line pumps usually have the motor inside the encapsulation through which the water circulates, this does not allow maintenance or change the motor in case of breakdown.
What usually happens with this type of water pump when we submit it to the circulation of hot water, is that there are internal expansions, and this ends up flooding the inside of the engine.
When this type of motor breaks down, the entire pump is unusable and irreparable, and we are forced to look for the same pump, or to look for a risky alternative.

Why did I make my own homemade centrifugal water pump?

Or I could also say

MAKE YOUR OWN HOMEMADE CENTRIFUGAL WATER PUMP FOR LESS THAN 15€

I thought the centrifugal model was the most convenient for my use in hot water circulation.
Because also, due to its design, the water circulation and the motor can be in different places, and that inspires more confidence than the pumps where the motor is inside everything.

So my homemade water pump will have the engine on the outside, that's crystal clear to me :-D

The way I built it, I can see everything in full operation.
I can replace anything in case of a breakdown very quickly and easily.
It's designed to replace any of its few simple elements.

It's really cheap. For less than 15€. So easy and cheap that you can make a dozen without breaking a sweat or breaking the bank.

Advantages of building your own centrifugal water pump:

• Super economical.
• Very easy to build with easily available materials.
• Quick and easy maintenance and repair.
• Completely removable, no botched jobs, no glued joints between moving parts.
• The rotor and motor are separate, which guarantees that expansion or water leaks will not ruin your motor. (the stray drops will fall outside without touching the motor in the least)
• If you use a DC motor, the power and flow will be adjustable from the voltage, and if you want to improve its performance you will only have to change the motor (commercial pumps force you to buy another new pump with the desired performance)

And without further ado, let's put on our gloves and get to the point.

Materials needed to make the centrifugal pump

List and prices

For the motor and its supports

For the motor body (syringe) and its supports

For the casing
(I can't estimate prices here because I already had this material, although the cost of this type of material is ridiculous)

Identification photos

Building the rotor

The rotor is the most important part of the pump, it is of little use to have a good motor if the rotor does not move the water well.
The rotor has to be of centrifugal design, if not, it will not be a centrifugal pump.
You can also put some blades from a toy boat or something like that, but it will not be centrifugal nor it will be

This is the rotor that I have used, I have taken it from an old centrifugal pump:

To do it, you only need some pieces of plastic, of uniform thickness, a fretsaw, and a little patience. You cut between 2 thin and flat bases of the same size in the form of a circle, with a diameter equivalent to the thickness of the syringe (the larger the more power but the greater the risk of it rubbing against the syringe and damaging it; the smaller the diameter, the greater the risk of it rubbing against the syringe and damaging it. easier to place it in the center of the syringe but less power)
It is very important that each of the 2 bases have a minimum thickness, between 2 to 4 mm approximately.

Keep in mind that the bases will have a hole each in their center, and the axis will pass through these.
If the bases are very thin, it is possible that these holes will deform, or will not hold the axis firmly.

Now, inside between the 2 bases (as if it were the filling of the sandwich), we place the walls in the form of spirals.

And the spirals must be shaped like this, and are set up as follows.
As shown in the drawing, we draw 3 imaginary axes (black lines).
The spirals (red lines) connect each line on the inside to the next line on the outside, look at the numbers.
This trick is important, because it is the way to respect the measurements, otherwise you may get a weird lettuce. 

We glue the spirals to the circular base with Epoxy glue, and cover the roof base.
Finally, with the drill and delicately, we make a small hole right in the center.
The hole will be the size of your axis.

Prepare the sealed bearing

All water pumps use a special seal called an O-ring, which is what allows the shaft to rotate in a waterproof manner without water passing through it.
But sometimes it is difficult to find this type of seal.

I propose something that is within everyone's reach, it is effective, and it is economical.
Removing the sealed bearing from a computer fan
A computer fan can be found in any computer store at a very low price, between 2 and 4 euros.
Buy the cheapest one.

The bearing that we will find in these mini fans can be of the bearing type, normally it will be
The fan that uses a bearing bearing is distinguished because they are like 2 cylinders one inside the other, or simply a metal body with a hole, the first one turns much better, but both are valid for our purpose.

Remove the sticker and you will see a small plastic circle, this plastic is what holds the propeller.
Remove it with a screwdriver by prying it off:

You will see the bearing in the center inside a plastic cylinder.
This cylinder is stuck to another outer metal cylinder.
Pry between the two until you can remove the inner cylinder with pliers.

You can test the tightness by blowing or sucking on the cylinder with the axis inserted.

Modifying the syringe

We are going to modify the syringe so that it is able to move the water in a sealed manner, andso that it has an inlet and an outlet.
In the 12mm hole, we will insert the polyethylene elbow, in order to be able to attach a tube to this part of the syringe for the water outlet.
The water inlet is already implicit in the syringe tip (where the needle is attached)

• A) Water inlet
• B) Water outlet
• C) Reserve this space for the clamp that will block the the cap here
• D) Small holes for screwing the syringe to the housing

To fit the elbow here, we have to cut it in half, because we don't want an elbow, but a nozzle.

Cut where the red line indicates.
We have to use the area that I painted green, which is like a spring to help hold the tubes.
I use this spring as a base to stick it inside the syringe.

And we stick it as seen in the following drawing....
What is painted yellow represents Epoxy glue, it is applied inside and out.
Epoxy glue sticks and seals.
It dries completely in 24 hours, although the manufacturer says it dries in a few hours, it is better to wait.

What is painted orange, represents the Epoxy repair putty, the kind that is sold in the dollar stores, the typical 2-color clay, which is mixed and hardens.

It is also advisable to let it dry for 24 hours.
With the putty, what I get is a better seal, and hardens the joint, so that it resists sticking in case of accidental knocks or twists.

While the assembly dries, we are going to prepare the axle pin, the part that acts as a plug, where the axle goes through the syringe, turns, and is watertight.

We cut the piston part of the syringe, it is the widest part that pushes the liquid from the syringes and that is covered with a large black rubber.
In this we make the hole the size of the bearing set that we previously removed from the pc fan.

The hole in the piston has to be as centered and straight as possible, if we do not do it well, then the pump will have lots of vibrations.

The sealing rubber will not really seal much, because it will have holes so that the shaft can go through, but it will be what fits the piston perfectly inside the syringe without moving.

The sealing is done by the bearing, and the O-ring that we will put on it.
It has to be like the photo: (I have put it with the box so that it can be seen more clearly)

The idea is this:

Green: The piston with its rubber.
Orange: The hole and the bearing glued.
Small blue: O-ring(s)

The O-ring(s) depends on the size and shape of the whole thing. You may need 1, 2 or 3 O-rings... depending on how you see the gap filled, the bearing quality and tightness.
Of course, the O-rings are always on the outside of the syringe, so you can manipulate them or change them if they break.

So Finally, the syringe is left with all its assembly, but still without the clamp that blocks the rubber stopper:

The piston with its large black rubber is what holds it in place.
So that this rubber is locked in position and inclination, and the centrifugal force does not suck it in, we have to put a metal clamp on the outside and tighten it well. We will see the clamp placed at the very end.

Build the body of the box.

The box will be the one that encloses the entire mechanism and will separately interconnect the rotor and the motor.
We will make this box with marquetry wood.
I chose this wood that is not only resistant but also very manipulable, however, if you want to make it out of plastic or sheet metal, any option is valid.
The difference will be mainly the difficulty of handling it.

We will cut 2 boards, each measuring 10mm wide and 8mm high.
And we will work both boards according to the pattern in the drawing, and I will explain to you below is the meaning of each color:

If your syringe matches this size, you can print this template and use it on the wood

We will join the 2 boards and with a drill and a drill bit (a drill bit the size of the large screw) we will make the holes for the blue circles, going through the 2 pieces of wood.
In the wood in front we will drill the black marks, with a drill bit the size of the screw small-thin, to make that horizontal shape you can make several holes.
Note that the measurement of both (4 cm) coincide with the grip of your syringe.
We drilled the brown wood on the back, it will be the hole for the motor and the guide-rail for the “Ele” that will hold and adjust the height of the motor.

The front board contains:

• In the corners the holes for the screws that close and join the 2 boards.
• The holes for the screws that hold the Syringe.
• (Between the holes of the Syringe) The hole where the Axle goes through.

The rear board contains:

• In the corners the holes for the screws that close and join the 2 boards. boards.
• (Between the holes in the syringe) The hole where the Axle goes through.
• Rail that holds the motor support.

Observations on the box.
If these wooden boards are going to be exposed to humidity, or to the elements, it is advisable to protect it with some varnish, or something to cover it.
I have covered it with aluminium adhesive tape.

Adapting the electric motor to the box

The electric motor goes on the back of the box.

An “L” (in the cyan drawing) with a clamp (in the yellow drawing) will be the body and support of our little motor (in the black drawing), which will also be screwed into the box (green stripes).

The rail-shaped hole where the “L” mentioned is held, has that shape to allow the “L” to be raised or lowered to adjust the height according to the diameter of the motor.

Special attention when we tighten the clamp, because we can very easily break the cylindrical magnet that has the interior of the motor.

The orange piece that joins both axes (syringe-motor), can be made of wood or plastic.

It is important that it has a large body, so that if at any time the syringe were to leak water, it would hit this piece, and never with the engine.

If at any time an axle does not hold well to this piece, we can cut a strip of aluminum from any soda can, and wrap this strip around the axle in question, so that the strip is between the orange piece and the axle.

PHOTOS OF THE COMPLETELY FINISHED HOMEMADE CENTRIFUGAL WATER PUMP

Homemade centrifugal pump performance

Performance can vary with many things, assembly quality, friction.

You can lubricate the shaft in the bearing part, being careful that the lubricant does not reach or wet the piece that joins the 2 shafts, as they could slip and fail the transmission.

Performance can also be reduced or increased with the voltage applied to the motor, that is, the more volts the faster it will go. the motor and vice versa.

In this setup, my time to fill a 1-liter bottle with 12 volts is 8 seconds.

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