# Diy Check Valve



## jbolt (Nov 27, 2016)

Not a real sexy project but the check valve for the coolant pump on my CNC mill conversion got contaminated and stopped working so the pump will not keep a prime. I was not able to successfully clean it and it is not serviceable. HF does not sell the check valves separately. I ordered a better quality one from Northern Tool but I got thinking it would not be that hard to make and also make it serviceable. 

So here is my interpretation of the 1" DIY check valve.

Parts used are:
(2) pvc 1-1/2" slip x 1" female thread reducers.
(1) pvc 1-14" plug
(1) pvc 1-1/2" slip x 1-1/2 Male adapter
(1) pvc 1-1/2" slip x 1-1/2 Female adapter
(1) pvc 1/2" x 2" piece of sch 40 pipe
(1) 1-1/16" ID x 1-3/16" OD x 1/8" O-ring
(1) 3-1/2" length of old arrow shaft (7mm). A 1/4" aluminum rod would also work.
Scrap piece of 1-1/8" delrin rod
Light weight springs from my misc parts bin.

The o-ring fits inside one of the pvc 1-1/2" slip x 1" female thread reducers. The OD of the o-ring is smaller than the ID of the reducer so I made an o-ring keeper out of the 1-1/4" pvc plug.







The OD of the keeper is turned larger than the ID of the reducer. The reducer ID is turned to create a press fit for the keeper. The reducer has an eight sided end and because the fitting is molded the slip part of the fitting is not straight but has a slight taper. 



Using parallels to set the fitting square in the lathe chuck I turned the eight sided end round but slight larger than the slip area and faced off the end to make it flat so it can be turned around in the chuck and held square for inside turning.






Here is the o-ring and keeper pressed in.



Next was to remount it in the lathe and taper the inside. The taper cut was 45 deg.



Next is the valve and guide rod. The valve is from 1-1/8" rod of Delrin I had and is about the perfect size. I started with a 45 deg taper for the plug but after testing, to get a proper seal, the final angle was 35 deg. 



I was not sure how heavy the valve could or could not be so I error-ed on the side of lighter and used a piece of an old aluminum arrow shaft for the guide rod. (nothing goes to waste in my shop). In the end a solid aluminum rod would work fine. The arrow shaft is pressed into the Delrin.



The valve guide rod needs a guide so this was made from a short length of 1/2" pvc pipe. The guide rod hole was drilled in the center of the pipe and then mounted on a mandrel and turned to slip fit inside the 1-1/2" Male adapter. The ID of the Male side of the adapter was also turned to remove the taper and make it round.









Here is the valve ends partially assembled.



After testing, to get a good seal, the valve needed more weight so I used some light weight springs I had saved from something else and used plastic shims to set the final pre-load.



Here is the completed, fully functional and serviceable check valve.


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## Terrywerm (Nov 27, 2016)

Nice work, Jay. Once again, necessity is the mother of invention.


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