metal pump idea i had

[Justice_Drencher]

i just had an idea about how to make a metal rod pump without any special tools. here's the concept. the only downside i can see to this is the need for tape on the grip since the threaded rod would be quite uncomfortable to hold. anyways that's about it.

- with thought, Justice_drencher

[SSCBen]

It's an interesting idea.

I would recommend covering the entire length of the threaded rod with a plastic tube or something else so that you don't have to deal with the threads cutting into the plastic pump cap. The threads offer an advantage on the grip end in that you could screw on a grip, too.

You might need to balance buckling strength of the rod against weight. A thicker rod would be heavy. Buckling is the word for a rod bending when you push on the end of it in the direction of the rod. A plastic tube around the threaded rod could help prevent bucking. I suspect a 1/4" threaded rod would be around ideal.

It would be easy to prototype, as you're aware, so I'd suggest trying it out and reporting what you find. If it ends up too heavy or has some other problem then you can improve that in the next version.

[Justice_Drencher]

what # O-ring would you recommend because the pipe would be 1/2" and the O-ring would have to be taller than the hex nuts holding it in place. I also fear that the hex nuts would not fit in the 1/2" pipe.

with fear

-Justice_Drencher

[SSCBen]

1/2" PVC pipe is only nominally 1/2". In reality the inner diameter varies a bit but is around 0.602" according to this table.

I think if you use a smaller threaded rod then there won't be any problem with the nuts fitting into the pipe. But in that case, I don't think hex nuts would seal. I would recommend checking McMaster for something that would have a side that would seal better. Maybe you'll have to combine the nuts with washers and use epoxy or something else to seal the nuts to the washers. I don't know, this will require experimentation. But I think it's probably still possible to make a better pump with off-the-shelf parts.

I used #9 O-rings when making the APH with 1/2" PVC pipe for a pump: http://www.sscentral.org/homemade/aph/parts.html

[Justice_Drencher]

hi Ben sorry i didn't reply sooner. Ive been busy with stuff and I have been busy actually making a prototype of this pump which i finished today. i found out that 1/4" threaded rod just as you suggested was perfect so i thank you for that. 1/4" nuts also don't interfere with 1/2" ID PVC pipe so that was quite a relief. for the seal i used assorted rubber washers from a hardware store i went to. the only thing i don't like about the rubber is that its on the harder side. Ive kinda tested its seal and it is air tight if it will pump water im not sure Ive filled some 1/2" PVC pipe with water and it pumped it all out without leaking. however i do understand your point in hex nuts not sealing, i believe and i might not be right here but Teflon tape could be able help with that problem. or might not i haven't tried it yet. i have some pictures of the completed pump i haven't tested it with my APH yet due to the threads not being covered yet. but i hope i will be able to improve with the next design. if anyone wants to know the price for this 24" pump was in total-6.58 USD which im not sure if that's expensive or not. anyways here's some pictures of the completed pump let me know anything you would change about my layout.

[Justice_Drencher]

quick update Ive tested this pump on my APH and it worked 100% without leaking, i just had to tweak the design a little. all i did was add another rubber washer and tightened the hex nuts until i couldn't anymore and taped the threaded rod so it does not damage internals. i also have a more accurate calculation about the pumps price, its more like 3 dollars for the completed pump once completed. for all the total parts its 6.58. overall i am pretty happy of how this came out, and i was not expecting for it to work the first time, i will definitely make more of these metal pumps for future projects. here's some photos of the completed pump.