# Make a small check/clack valve



## bille1906 (May 2, 2009)

I have made several check valves for my projects and it seems like each time, I have to re-design one because I didn't keep detailed dimensions.
So here is a hand drawn diagram of the last set I made. This is for a 1/8" ball which is about as small as you would normally want to go and it is fairly compact. It can be used for both the inlet and outlet valve on pumps


















Here is a close up of the valve.








Here is a picture of the last valve I made. You can see that here "B" has been turned into the valve body.
The 5mm thread and o-ring help to keep the size down as metric o-rings are only .040 thick vs .070 for standard

if anyone wants a jpeg copy of the diagram, send me a private message with your email address.


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## seadawg (Jan 2, 2008)

Bill, this is AWSOME. Maybe expound a little on the "D" bit. I the drawing above, is the bit double ended?


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## redbeard (Jan 2, 2008)

Hi Dave, 
Look here; 

http://www.mylargescale.com/Community/Forums/tabid/56/afv/topic/aff/11/aft/126370/Default.aspx 

on 09 Dec 2012 07:57 AM That's his post on making the pump. 
Larry


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## HMeinhold (Jan 2, 2008)

Bill,
if you make a D-bit, use an angle of


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## bille1906 (May 2, 2009)

Hi Dave
Here are the photos of the bit. it is double ended








This end is used to make sure the 3/32" hole is round and centered and to make the seat square. It ia my own design and will actually work well alone
The piwce is turned to size on the lathe and then it was carefully ground on the grinder but a mill wouls have been more accurate 








this end is for the final touch to get a knife edge seat which will form to the shape of the ball more easily.
It is Kozo's design. the slope is 15 degrees and the back slope( to make the cutting edge) I believe should be 30 degrees but even a flat will work as we are not drilling with it , just kissing the seat


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## Ray Cadd (Dec 30, 2008)

Neat. I want to try this. I'm not entirely clear on the profile and setup of the 'D' bit. Do you use that on a mill, lathe or ? Do you have a more detailed drawing of that process?


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## HMeinhold (Jan 2, 2008)

Bill,

here is the shape/D-bit recommended by Henry Greenley. This is the one I use now.



and



The D-bit seems to be in need of some resharpening







.
Regards


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## bille1906 (May 2, 2009)

Hi Ray 
It is difficult to explain or even show but I will try 
Henner's photo above shows his D bit and as he says it is a bit dull. what looks like a bevel on the top is, I think, actually where it has dulled. 
His bit has about a 30 degree slope which gives the ball seat the shape in the drawing. I use a 15 degree angle which is recommended by Kozo. either will work and even one with no slope will work, just not as good. 
In any event they will all work better than just drilling two different size holes for the following reasons. 

1. drill bits do not cut perfectly round holes so the seat made by the tapered point of the drill bit will never be true and will not seal 
2. A tapered seat creates an area where the ball seats, that is too wide and therefore the sealing force of the ball is spread over a larger area which reduces the seal 
3.The diagram in Henner's reply shows a seat with a zero width. This will make a good initial seal and with a little seating of the ball with a hammer blow, the seal will be perfect 
4. By it's nature, a D bit drills perfectly round and true holes. 

Now, to the making of one and it's use. 
A d-bit is only a rod which has been ground so that one half of the circular cross section is all that remains on the face you will use for cutting a hole. A back slope is then ground to make a cutting edge. On our seat tools we 
have an additional slope to make the pointed seat 
The top photo of the double ended tool I made shows two different diameters. This was done to make certain the small hole is centered. This was turned on the lathe to the shape shown and then ground to make it a d-bit 
I don't like to drill much with d-bits as a drill does a faster job so I drill a few thousands short and then finish off with the d bit. 
For the bottom one in my photos and in Henner's one, no tool is needed other than a bench grinder, though you can do it on the mill also 
The check valves are entirely done on the lathe including the d bit operation. The side hole can be done on the mill or drill press. 
D-bits can be used on the mill or lathe or even in a hand drill. 

Somewhere in one of Kozo's books, he has done a diagram of making a d-bit which as I remember shows it very clearly.
If anyone has that, maybe they can attach it here.


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## Nutz-n-Bolts (Aug 12, 2010)

Just a great thread Bill. Thanks for sharing with such great detail. I started a thread a while back ( Thread Link ) on check vale/pump design and got some really great feed back in that. We also debated the merits of differently shaped seats in that thread. Really enjoyed seeing pictures of a variety of D bits here. Thanks again for such a great post.


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## Ironton (Jan 2, 2008)

Bil, 

In windows anyhow, if you right click on the diagram you posted you can save it. No need to go through individual requests unless you are going to send a better picture. 

Thanks for the info. Very informative thread.


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## seadawg (Jan 2, 2008)

I believe this is the next step (for me). I am able to create shouldered bushing that are threaded in the center to attach valves and sight glasses to the boilers I build. Check valves (and pumps) seem to be the next logical step. And it seems plans to build them (valves and pumps) are somewhat scarce on the internet, probably too easy for most machinists.


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## Ray Cadd (Dec 30, 2008)

Ok, now I see, makes total sense. It's almost like a cross between a drill and a boring bar, sort of. The 'D' end drills the stepped, centered holes. The other 'tapered' end cuts that reverse tapered seat, minimizing surface contact at the ball. Which, then gets set right with a tap of the mallet. Seems super easy! 

Now, what about hardening the drill rod? It seems, according to your notes, you heat and quench twice?


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## HMeinhold (Jan 2, 2008)

Posted By Ray Cadd on 21 Feb 2013 02:05 PM 
Ok, now I see, makes total sense. It's almost like a cross between a drill and a boring bar, sort of. The 'D' end drills the stepped, centered holes. The other 'tapered' end cuts that reverse tapered seat, minimizing surface contact at the ball. Which, then gets set right with a tap of the mallet. Seems super easy! 

Now, what about hardening the drill rod? It seems, according to your notes, you heat and quench twice? 
Yes, after the first quench the drill rod is glass hard and brittle. The second anneal/quench "softens" it just a bit.Fortunately the colors of steel during heat treatment are a good indicator for the temperature. "Straw" color gives just the correct compromise between brittle and not cutting.
Regards


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## Ray Cadd (Dec 30, 2008)

Ok, got it, thanks Henner!


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## bille1906 (May 2, 2009)

One other thing 
After the first quenching, the material will be black so you will need to sand off a spot to be able to gauge the color change in the drill rod


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## HMeinhold (Jan 2, 2008)

Posted By bille1906 on 21 Feb 2013 05:58 PM 
One other thing 
After the first quenching, the material will be black so you will need to sand off a spot to be able to gauge the color change in the drill rod I have not tried it, but some text books suggest covering the D-bit in soft soap for the first anneal to avoid oxidization.
http://easyweb.easynet.co.uk/~chris...t/t-ht.htm 
Regards


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## Mk (Jan 7, 2013)

I used a stainless steel bolt and turned it and then I grinded it to shape and it doesn't get dull, not even a little.


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## bille1906 (May 2, 2009)

Hi Marinus 
I have used SS before also with good results but the drill rod is just a little better if you temper it right


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## Skeeterweazel (Feb 11, 2014)

For an axle pump set-up, would you use 3 of these valves, or does the one closest to the boiler need to be different?
Thx.
Marty


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## bille1906 (May 2, 2009)

Marty
They can all be the same. Sometimes the size needs to be changed for the clack valve because of it's location


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## Skeeterweazel (Feb 11, 2014)

Thx. Clack valve needs to bigger of smaller? Why?


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## bille1906 (May 2, 2009)

The clack valve is often on the side of the boiler in plain view and we sometimes want it to look similar to the prototype so we may need to make it smaller to be in scale.
As far as the working of the valve, a 1/8" or larger ball is desirable. It is harder to get smaller valves to seal well. If the clack valve is in the cab and you have the room, you may want to make it larger than the valves in the pump as larger is usually better

one other thing, if you look at "D" in the sketch which is the limiter of the ball movement off the seat, I said .020 to .025 which is in keeping with the general rule of 1/6 the ball diameter. I recently read an article that recommends 1/6 for hand pumps and 1/8 for axle pumps, so I would use .015" for the clack valve.


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## Skeeterweazel (Feb 11, 2014)

Thx, Bill. May do a system down the road. Trying educate myself.


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## Skeeterweazel (Feb 11, 2014)

Came across this YouTube vid today re: D-bits.


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## Ger  (Jan 13, 2009)

Interesting video on making a D bit. However, I think that most readers of this forum will not have the machinery shown.

A D bit is not always necessary. In _Manual of Model Steam Locomotive Construction_ by Martin Evans, on page 130 he discusses making a seating for the ball as a separate fitting. This is left with a turned finish. In addition, you can turn a cone shape in place of a flat face cut. Then the fitting is pressed or screwed into the body.

H Meinhold in his post of 2/20/13 referred to a seating shape per Henry Greenly. This was not included in the post. Henry Greenly's shape is clearly shown on page 119 of _Model Boilers And Boiler Making _by K.N. Harris. The entire book is available as a free download. This a great book, just about everything you need to know about model boilers and fittings.

If you do a Google search for the book, look for fastonline.org 

Gerald Pierce


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