pic of the setup for truing valve seats to the stem, and pic of undercut seat

pic of the setup for truing valve seats to the stem, and pic of undercut seat

Joined: March 28th, 2002, 6:54 pm

December 28th, 2010, 4:05 am #1


and here's the pic showing how to set up for a "toilet plunger" (undercut)valve

Last edited by classicalgas on December 28th, 2010, 4:57 pm, edited 1 time in total.
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Joined: August 16th, 2006, 10:39 pm

December 28th, 2010, 5:07 am #2

what do I ask for at the tool supply shop??? You use that by hand or mount valve in lathe in 3 jaw chuck???
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Joined: October 21st, 2001, 3:36 am

December 28th, 2010, 5:48 am #3


and here's the pic showing how to set up for a "toilet plunger" (undercut)valve

That gives me an idea to work with; valves are on my project radar.

Does the undercut valve edge give to help seal? Is the seat flat?

Last edited by bigbore on December 28th, 2010, 5:48 am, edited 1 time in total.
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Joined: March 28th, 2002, 6:54 pm

December 28th, 2010, 4:54 pm #4

what do I ask for at the tool supply shop??? You use that by hand or mount valve in lathe in 3 jaw chuck???
they are readily available. I've seen them called spot facing cutters and also piloted end mills.I turn that setup by hand, with a tap handle..seems to prevent chatter.
Last edited by classicalgas on December 28th, 2010, 4:55 pm, edited 1 time in total.
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Joined: March 28th, 2002, 6:54 pm

December 28th, 2010, 4:57 pm #5

That gives me an idea to work with; valves are on my project radar.

Does the undercut valve edge give to help seal? Is the seat flat?

flows/flexes slightly to help make the head seal at low spring pressures.
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Joined: May 2nd, 2006, 4:27 am

December 28th, 2010, 11:09 pm #6

what do I ask for at the tool supply shop??? You use that by hand or mount valve in lathe in 3 jaw chuck???
<p>It's 15/32 diameter and opems up the valve body to the max size and cuts the seat at the same time.</p><p>http://www.wttool.com/index/page/produc ... pot+Facers</p>

http://home.comcast.net/~peterdragin/index.html/
Last edited by peterdragin on December 28th, 2010, 11:10 pm, edited 1 time in total.
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Joined: March 28th, 2002, 6:54 pm

December 29th, 2010, 12:41 am #7

it fits more valve bodies than something with a bigger pilot.
Last edited by classicalgas on December 29th, 2010, 12:42 am, edited 1 time in total.
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Joined: August 16th, 2006, 10:39 pm

December 29th, 2010, 1:30 am #8

<p>It's 15/32 diameter and opems up the valve body to the max size and cuts the seat at the same time.</p><p>http://www.wttool.com/index/page/produc ... pot+Facers</p>

http://home.comcast.net/~peterdragin/index.html/
I am trying to get my valve to seal with a low spring pressure.....the real light valve spring gave me the flattest curve on a shot string but it vented the tube pressure near trhe end of the shot string. I am hoping a different style valve head and seat will seal better at the lower pressures.

What are you using for valve stems??? drill rod ? What size and what size reamer to fit it? I will drive out to WTT after I get a list worked up....I spend too much when I go ina place like that

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Joined: May 2nd, 2006, 4:27 am

December 29th, 2010, 2:03 am #9

<p>Yes I use 15/32 as it opens up the valve to the bigest you can go with out weaking the valve threads. The stock size is .436 and the cutter is .471  and the base diameter of the threads is .560 so it leaves you a .045 wall thickness after it opened up with the spot face. I use 3mm dowel pins for the valve stem and bush them for a pilot in the spot face cutter. They have a 1/8 pilot hole so a bushing is needed. On older valves that are worn a bit I ream them out to 1/8 and make new stems with a 1/8 dowel pin.</p><p> </p><p>here's the valve block before and after the bore is opened  up and lapped for a Delrin stem.</p><p><img alt="valveA.JPG" src="http://www.network54.com/Realm/tmp/1293 ... PG"></p><p> </p><p>Some of the tools I use to lap the seat and lap the stem. The stem on the left is VERY VERY hard steel and used with compound, the other is just sandpaper on a over size stem for sanding the valve seat.</p><p> </p><p><img alt="valveC.JPG" src="http://www.network54.com/Realm/tmp/1293587857.JPG"> </p><p> </p><p>A stock valve and a full blown 79 valve, the blue valve stem is a type of Delrin called Turcite it's jsut a bit softer than white delrin.</p><p> </p><p><img alt="valveB.JPG" src="http://www.network54.com/Realm/tmp/1293588070.JPG"> </p>

http://home.comcast.net/~peterdragin/index.html/
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Joined: August 16th, 2006, 10:39 pm

December 29th, 2010, 2:16 am #10

that gave me a very flat string but vented tube at bottom of shot string. That valve has been holding pressure since last night with a stock valve spring at 2500 psi. valve leaks down with the softer spring. I wonder if the blue valve head would be the trick to solve the venting of the tube with the softer spring.

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