How to build a barrel pump - Page 2 - Mountain Buzz
 



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Old 02-24-2015   #11
 
Salt Lake City, Utah
Paddling Since: 1987
Join Date: Sep 2012
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Caverdan has it right. It adds an additional gliding surface to keep the plunger centered and it also provides additional support for the straps.

Best of luck. I'm interested to hear how hard these are for others to build. Remember the tolerances do not have to be too tight.

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Old 06-28-2015   #12
 
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Kalispell, Montana
Paddling Since: 1997
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I've finally started mine.

I built the plunger and barrel. I put it on the bottom cap and I couldn't push it down due to air pressure. Very impressive.

I still need to build the hose assembly.
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Old 02-02-2017   #13
 
Great Falls, Montana
Paddling Since: 2015
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Love posts like this and registered just for this. I am considering building a couple of barrel pumps after seeing this post and seeing the price tags for 6" pumps. I have a few questions.

1) I am unclear on where the gasket (shown in pic 7 and 8" goes and what it does in the pump as whole.

2) What kind of dishwasher check valve you suggest for this. I see various designs out there and Im not sure which valve to obtain for this project.

3) Why rivet the top two pieces together and not just use pvc primer/glue? Simply to avoid buying the glue if you did not have some on hand or is there something Im not getting here?

4) The top cap remains unglued from the main body, correct? I do not see how that stainless pan screw holds it together under vigorous pumps and does not mutilate the discs on the up stroke. Could you expand on that a bit?
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Old 03-10-2017   #14
 
Salt Lake City, Utah
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1. The pictures in 7 and 8 are the jigs I use to cut the gasket material. they are slightly larger than the bore diameter of the pump. I cut them with an adjustable hole saw and then sandwich a piece of foam between the two pieces (you need 2 large and 2 small plates) and use a razor blade to cut the foam.

2. I use the oatley air vent for my check valve
https://www.amazon.com/Oatey-39012-L...oatey+air+vent

3. I rivet the top pieces together to hold the handle/strap in place and the PVC and whatever you made your other parts out of (Vinyl/HDPE/UHMW/polypropylene) probably will not glue together.

4. The SS screw that holds the top on does not mutilate the top disk because there is space between the disk and the cap. The space is created by the end cap that makes up the plunger assembly. It is about 1 to 1 1/4 inches tall. This will hit the top of the cap before your screw hits the disk.

These pumps are easy to build, but they take a bit of work and time. There is a reason they charge $200 for a quality pump!
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Old 03-13-2017   #15
 
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Belgrade, Montana
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Thanks unlucky for the detailed instructions. Went together without hitch. I'm going to tweak the gasket a little and see what the pros and cons are as to thickness and diameter. I'll also play with how much to cut out on the lower gasket holder (spider thingy, for lack of a better term). I think I may have cut too much and don't get enough support out of it as I should. It works fine but bleeds of a little pressure.

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Old 03-13-2017   #16
 
Salt Lake City, Utah
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Elkhaven - It's nice to hear someone has used the directions and successfully built one. Looks good! I have yet to run into someone on the river who has built one.

I noticed yours does not have a base. They are a beast to put on when it is all put together but it is possible.

I don't think the fit of the "spider" is not too important. A little loose seems to be ok. I think the gasket life may be better with a tighter fit though.

As far as gasket thickness goes if the fit of the plunger is good you can use 2mm foam and it offers very little resistance. If your space is a little looser you will need the 4mm foam. It has a touch more resistance especially at first but they do loosen up a touch with use. Regarding the diameter of the foam I don't think it matters to much as long as it's larger than the pipe. The foam squishes to fit. Diameter does not effect resistance as much as thickness does.

I have not worn a gasket out yet. I have seen some used commercially for 3-4 years and still no failures.
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Old 03-13-2017   #17
 
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Belgrade, Montana
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I love this kind of shit. I didn't even need one, but the project has been eating at me ever since I saw this thread...

What did you do for a base? I thought about bolting something on and sealing it with neoprene washers, but decided against it for this one. I have enough parts to make another, so I'll do something for that.

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Old 03-13-2017   #18
 
Salt Lake City, Utah
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If your pump bleeds a little air than your plunger disk has too much clearance. Step up to the 4mm craft foam. You only need about 1/16" clearance for the plunger.

Typically when people test a pump they plug the end of the hose and jump up and lean on the handle. This can momentarily generate 15+psi. If your plunger clearance is small it will hold this pressure even with 2 mm foam. If your pump bleeds a little bit of air you won't miss it too much at 2 psi.
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Old 03-13-2017   #19
 
Salt Lake City, Utah
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I didn't realize I didn't post pictures of the base. I use the same material for the base. Choose your shape. Some are rectangular and some are round with a flattened side. Use the same hole saw to make the base. I use 2 stainless steel counter sunk 1/4-20 X 3/4" bolts with nylocks and fender washers on the inside. Just put a bit of silicone between the base and cap. I put a touch around the countersunk head too. There is not much pressure to leak out I just don't want water leaking in if I'm standing in the water pumping.
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Old 03-13-2017   #20
 
Denver, Colorado
Join Date: Aug 2015
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All of these are designed so that the internal gasket is airtight on the push stroke, but lets air past on the pull stroke, right?
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