My first Stirrup Pump build...

[Big-E]

Hi all,

It's been a long time since I've posted anything; I've been extremely busy, but I haven't stopped spudding.

Anyways, here's my latest build, I still have some things to revise, but I've decided to bite the bullet and build a stirrup pump. I got sick of rebuilding bike pumps and this is the result.

It's made from 3/4" copper. The piston is made from a 3/4" machine screw anchor and JB Weld to seal all the gaps in the piston head. it uses a floating o-ring. the pump rod is steel all thread.

It has a 3/4" check valve, which I need to modify to eliminate dead space at the bottom of the piston stroke, since it's fighting me a bit past the 140 PSI mark. I've gotten it past 200 PSI so far (the gauge is bad, I need to replace it and it only goes to 200, but It was what I had in the parts bin).

The airline is mostly paintball stuff, rated at 2500 PSI. The schrader chuck is rated to 300 PSI or so, but I can swap with a quick disconnect fitting or plumb it in directly.

For now, I am using a shift knob for the handle, will be replacing it with a heavy steel pipe nipple for a t-handle most likely. the ball valve is for testing purposes and will be removed when the bugs are all worked out. I've used it with the Kopperbess, and it works great. I may integrate it into my next pneumatic, or make a similar pump to be integrated into it , since this pump is a heavy beast. Needless to say, the next project will have a QEV (or possibly a homebuilt piston).

I used a close coupling brass nipple as a sleeve for the pump rod, it was cut down after being threaded into the reducer. I didn't tape the threads at the top of the pump body to make servicing easy, plus, you only need a good seal below the piston head anyways.

The pump is lubed with Castrol synthetic automatic transmission fluid. The combo of lube, and the large check valve make it rasp and growl when you pump it, my wife says it sounds like a beast in heat, so for now, I'm calling this pump "The Beast".

I'll take pics of internals when I disassemble it to mod the check valve. Let me know what you think.







BTW, I've taken a lot of your past comments to heart, and I'm trying to step up my build quality on my latest projects. Stay tuned!

[far_cry]

nice work and nice looking pump

the first stirrup pump i build i used the same check valve you using right now

http://www.spudfiles.com/forums/air-pum ... 15794.html

soon after this valve fail .
i recommended to be very very careful with the pump ,if this water check valve fail plus that handle your pump have ,this will result a bad combination.

my wife says it sounds like a beast in heat, so for now, I'm calling this pump "The Beast".

yes the same sound i got with my first pump,but don't get used to it,you must find alternative. and get a smooth steel rod and make T handle

this is my second stirrup pump i build ,and it was success
http://www.spudfiles.com/forums/my-seco ... 18650.html

take a look for the check valve i build

[POLAND_SPUD]

yeah far_cry is right, those check valves are probably rated to 10 bar max or so

have you seen its internals ?? mine had just a small metal disk with some rubber, definitely not something that looks strong enough to handle high pressures... especially considering its large area

you can even build a much simpler check valve than the one posted by far cry

[Big-E]

Actually, the check valve is rated to 200 PSI.

I did design a check valve, I wanted to use a couple of 1/4" fittings, but the ball I have is not perfectly round, so it seals inconsistently. I'm hunting for a ball that will work; I have one from another pump, but the ball is plastic, and I'm not sure if it can handle it.

I may have another idea though; I have several steel balls from K'nex sets, does anybody know the size of fittings that will accept those for use as a valve?

I'm sure I can make one. I may check an auto parts store for PCV valves and take the ball from one of those.

Okay. Ditch the valve; Will do.

As I said, the pump isn't done yet, so anything still goes.

A T-Handle will go on it; I was going to make it tonight.

The all thread doesn't bother me, as I added a brass bushing to the top. If I trade out the rod, it will be for aluminum tubing, threaded at the ends to accept the piston, but I'd only do this to save weight.

I actually looked at lots of pumps on here already; That's how I got some ideas. Thanks for the input.

Edit: I like the connection method you used for the piston on your pump Far Cry, I may just go that way, If I can drill out my piston... Actually, I think I have an idea... Will post updates in a day or so!

[Brian the brain]

Definitely loose the checkvalve..

or prepare to loose your teeffff...

You can simply slide a aluminium tube over the threads..
It will prevent damage to the outer pumptube.

[Big-E]

Brian, totally understandable. I can't believe I didn't consider the pitfalls of this valve. Thanks for saving my teeffff Based on your prior experiences in that arena, I will take your word on it.

As for the aluminum tube , I'm probably gonna go with steel tubing instead, and whack out the allthread all together. I want to lighten the pump as well as make the pump rod stiffer, so steel tubing may be the best thing.

So far, I think everybody is giving some great input.

[Brian the brain]

Pretty soon the pump will be giving some great output!
Keep up the good work.

I love those square chunky fittings lik ethe Tee you used.
Wish we had them here.



Darn...I really am a spudder..

Who else would say something like that??!?!?!

[Hawkeye]

You can eliminate most of those fittings and hoses by just building a fill/ check valve into the gun itself. The pump then only needs the actual floating o-ring and nothing else.

[Big-E]

Okay, Here she is now. I love it! It's no longer "the beast" Because it's so much better! It's now, "The Beauty":



First off, I made my own check valve. Here's an exploded view:



Teflon tape let it leak. I used red LocTite instead. My brother taught me this trick from plumbing shop compressors. I can still service it, it's just harder to loosen the fittings. Works like a charm!



I took a Polyurethane High Performance suspension bushing (Energy Suspension) and shaved it down some, then using a deep socket, I hammered it into the coupler and reducer; this was to reduce dead space, and it worked great!




I sleeved the pump rod in steel tubing, drilled out the cap, and added a T handle.



She rocks now! A new 400 PSI gauge maxes out easily, and zero leaks!



Thanks for all the input everybody; What do you all think now?

Oh... Almost forgot... Here's what the piston looks like:



All feedback is welcome!

BTW, Brian, Those chunky fittings came from my local True Value Hardware, they have almost everything. I did get a rounded one for the gauge elbow, they were out of the machined fittings in 1/4".

[Brian the brain]

Awesome!

Just awesome.

I have a suggestion.
You can use inner bike tube or some flexible hose to sleeve the pump and handle so it won't get damaged with use.
Plus it will make it look pro.

Oh..I think it needs a stand too, if only to take the strain off the vital parts.

Great job!

[Big-E]

Yes, that's the next part. I'm thinking of a nice hardwood stand. I may have my friend, Dave make it; He's a very accomplished woodworker, plus, it'd make it look awesome.

I'll be adding bicycle grips to the pump handle; I have them in my garage.

[Demon]

Are the spaces on the piston perimeter acting like a check valve ?

Awesome pump!
At 400 psi, is it manageable to pump?

[Big-E]

Demon, The spaces at the bottom of the piston head are so air will flow past the o-ring on the upstroke. on the downstroke, the o-ring is forced against the pump tube wall and the top edge of the piston groove, creating a seal so the air can be compressed, and forced through my check valve.

It's way easier to pump. it's manageable to 400 PSI, but that last pump takes a little more effort. Up to 350 PSI it's like butter.

[clemsonguy1125]

Awesome, after seeing this I think I will try to make one, what size o-rings di you use, and is it type l or m copper

[Big-E]

I used a 3/4" machine screw anchor, it's a two piece steel fitting that is crushed together when you turn a machine screw in it, and it presses into whatever the screw is going into. I sealed it up with JB Weld Epoxy, and threaded it onto my rod. once cured, I used a dremel, a couple of files, and sandpaper to make the grooves for the o-ring and air relief notches.

The o-rings I used were:

5/8" I.D. (13/16" O.D.) x 3/32" wall for the piston
1/4" I.D. (3/8" O.D.) x 1/16" wall for the check valve.

I used thicker, L Rated 3/4" tubing for the pump body.