3d printing… the solution to my problem?

I have a small diaphragm pump. Its for a quadbike attachment for the farm.

Anyway, there is a small cover on the pump, little more than a 2p diameter hard plastic cover. with 2 ‘lugs’ for the screw fixings..

https://i.ibb.co/vJT3TLX/Diaphragm.jpg

I have had a look at the spares sections of the retailers, but doesnt obviously seem available. And a complete new pump is circa £300.

Is 3d printing the answer to my problem? I give the complete (cracked) one to someone, they measure/dimension it and print me a new one for a fraction of the price.
Would it be as simple as that?

Are there any features on the inside face? If not, just make something out of a piece of aluminum.

It’ll be easy to 3d print. Only question is whether it is up to the job. If it needs to be strong to hold pressure or withstand some heat then you might be better with another method. It’s also quite easy to mill from solid plastic or aluminium. If you could get away with a completely flat part then it could be hand fettled from aluminium or laser cut.

Looks like this on the reverse….

https://i.ibb.co/8DvNy8h/Diaphragm2.jpg

The pump pressure is 3.4 bar.

In the meantime im going to try plastic welding and some epoxy. But not convinced that will work….

It looks like it’s injection moulded from glass filled nylon or POM. If those properties are required then there isn’t t a consumer printer that could achieve that.

Is there an O ring to seal it onto the body? Does it ever need to come off?

No, no o-ring (strangely enough), and yes it does need to come off if need to replace the pump diaphragm itself.

There are services where you draw it out in a 3D modelling package and send it off and they will laser cut a piece of alu for you.

Is the back face flat? I’ve just got me a cnc milling machine…

Ok. Had a look at the piccie. I’d be inclined to start with a tube of JB weld. Failing that it looks easily enough made if you can sort out model of it.

I’ll knock up a drawing to see if someone can make one reasonably priced. No point throwing away a near new pump for a bit of plastic.

As to the original plastic one, ive used epoxy and strengthened it with a 2p coin on the face. Waiting for the expoxy to cure…
In the meantime, made a steel plate cover for it. It works insofar as i can handle a small drip leak and not pressurised spray.

What fluid/deposit sits behind that cover? Just thinking about material compatibility. I guess the cover doesn’t see any of the pressure? That should be within the diaphragm?

Could the backside be flat? It looks like there is some kind of lip. Does that provide any sealing? Could the screw hole lugs be chunkier to increase strength?

Does the thickness of the part matter? If it was twice as thick, would that be a problem?

Are you able to create an accurate drawing, or at least take accurate measurements?

I’d be happy to 3D print something for you and send over several parts (for spares) for an appropriate donation to my daughter’s Lego fund.

Let me know by replying to this or drop me a direct message 👍

Thanks Stumpy. I’ll see if i can knock up a drawing to see what you think!

Could the backside be flat? Yes, its ‘ribbed’ to provide strength to the plasitc internal face.
It doies have a stepped lip yes, probably to provide more sealing in absence of an O ring. However given the flat steel plate i made – it still works, i could put an O ring ot sealing material behind it.
Thickness doesnt matter. However the fixing screws thickness lugs do matter, as does the part area envelope. Outwith the envelope there raised fittings.
Whats in it? Its a quad sprayer for water/liquid fertilizer/herbicide.
The part does see pressure. It covers a diaphragm for the bypass (recirc for overpressure) – the pump pressure is set to 3.4 bar.

You can get data sheets for a lot of 3d printer materials now and there are glass/carbon filled materials out there that can take temps above 100 deg c.

Also check out multi jet fusion printers. 76 projects have one, they do garmin mounts etc. Very impressive parts.

You are either providing a 3d model (in stl format) or a drawing/original part, in the case of the latter they will need to charge for the time to model the part.

If the top is sat in thin air and not critical dimension wise don’t be afraid to beef it up.

Once you have it drawn chuck it up. Might be a print job or a cut job. My CNC machine is only 2.5 D so deeply complex shapes are tricky.