davidm
Seasoned Member
Posts: 109
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Post by davidm on Dec 9, 2009 23:24:45 GMT
I thought about a D bit with a sloped cutting face, after the event! Certainly mine seem OK. I'm glad someone else has thought of using a milling cutter, it's good to know that it's not a daft idea!
BTW, on mine the fitting on the outlet would have fouled the underside of the boiler so I mounted a T fitting directly on the pump, one arm to the clack, the other to the bypass valve which was mounted on the back of the LH tank.
David
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Post by Tel on Dec 22, 2009 11:33:38 GMT
There's always Tel's remarkable (pat. pending) D bit that makes a 100% reliable seat 100% of the time with just the lightest bash on a sacrificial ball  |
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Post by welshy on Dec 23, 2009 11:02:33 GMT
On my pump i used a slot drill to cut the hole and then turned a very short insert with the correct vee profile which i Loctited into the bottom of the hole i then give it the light tap with a ball as usual. This method was very easy and needed no special D-bits or cutters.
I also had to modify the pump outlet to clear the boiler.
Mike
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Post by drjohn on Dec 23, 2009 13:17:30 GMT
I have to say that I never quite understood the logic for the raised seat. I heard it's to accumulate dirt, which once accumulated stands a high possibility of getting under the ball when the dirt is disturbed by passing water. With a flat seat, no dirt accumulates it all passes through.
If there's another reason, I'd be interested to hear about it.
DJ
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Post by Tel on Dec 24, 2009 10:28:13 GMT
It's xxxxx times easier to form the seat for a perfect seal.
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Post by drjohn on Dec 24, 2009 23:45:22 GMT
But if you tap the ball off the straight, it's also very easy to completely ruin the cone.
DJ
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Post by Tel on Dec 25, 2009 18:46:47 GMT
Well, p'raps if you are tapping them with a jack'ammer or a piledriver.
The way I've done it ever since the Ark converted to steam is to make up a special brass drift, with a buisiness end a foofteenth smaller than the tapping drill size of your 'ole, and with a little dimple in the end made with the point of a centre drill, or, for preference, a spotting drill.Make sure the other end end of the fitting is solidly supported, drop in ball, slip in rod/drift and bash the outer end with a 'ammer - ONCE.
Over the years I've accumulated several of these drifts to cover most sizes I use, and, with care, they last for ever.
Other folk use and advocate making a little threaded guide bush and a smaller rod, but It's not really worth the trouble, nor nearly so effective IMHO.
Meanwhile, Santa bought us a day about 20° cooler than it has been recently, with about 1.5 in of gentle rain spread (almost non-stop) over the day, the best possible present ever!
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