Author Topic: what did I do wrong?  (Read 1924 times)

rsterne

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Re: what did I do wrong?
« Reply #15 on: April 30, 2017, 11:49:54 AM »
Should work.... I have never used a center drill to create the concave, if the poppet is collapsing into that cavity, then obviously the angle is too steep for the pressure you are running.... Flat will work, or you can turn a slight recess, or even use a drill point to narrow the seat if you don't want it just flat....

What is the ID of the throat, and the OD of the poppet?....

Bob
  • Coalmont, BC

fineredmist_7

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Re: what did I do wrong?
« Reply #16 on: April 30, 2017, 07:39:31 PM »
The ID of the throat is .254, and the OD of the poppet is ~.340.
  • Delta, Colorado

rsterne

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Re: what did I do wrong?
« Reply #17 on: April 30, 2017, 09:10:15 PM »
You probably don't need to bother with a concave seat.... flat should work just fine....

Bob
  • Coalmont, BC

fineredmist_7

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Re: what did I do wrong?
« Reply #18 on: May 03, 2017, 09:09:06 AM »
I machined a new valve stem and poppet last night. Will assemble tonight.
  • Delta, Colorado

fineredmist_7

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Re: what did I do wrong?
« Reply #19 on: May 04, 2017, 09:55:52 PM »
After I got the valve put back together, and the rest of the gun reassembled, the hammer seemed to get bound up in its tube. The only thing that I can think of is that the oil that was in there was preventing it from rubbing on the tube. I turned a 3/16" groove 1/8 " from the end of the hammer and superglued a strip of plastic to act as a bearing.
  • Delta, Colorado

rsterne

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Re: what did I do wrong?
« Reply #20 on: May 05, 2017, 07:53:59 AM »
Hammers do not need to be particularly snug in the tube, a loose fit is better than tight.... In addition, make sure there is an air vent both in front and behind the hammer, or alternately a channel or hole through the hammer.... to prevent air pressure (in front) or a vacuum (behind) the hammer from restricting its freedom of movement.... Lack of venting can cause extreme velocity variation, as well as low velocity....

Bob
  • Coalmont, BC

fineredmist_7

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Re: what did I do wrong?
« Reply #21 on: May 05, 2017, 08:10:42 AM »
The hammer was such a loose fit that when I  pulled the handle it was twisting. Then the corner opposite the handle would rub on the tube. I believe the plastic strip has remedied the problem. What sort of oil should I use on the hammer?
  • Delta, Colorado

rsterne

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Re: what did I do wrong?
« Reply #22 on: May 05, 2017, 12:32:16 PM »
Ideally none.... Oils will thicken in cold weather, often causing a drop in velocity.... I use a thin film of 30 wt. cut 50/50 with Moly Slip.... Some use a dry Moly or Graphite paste.... The newest trend is to MDS (Moly impregnated Nylon) hammers with a metal core (the Nylon is too light by itself, usually).... The heaviest readily available core is brass....

Bob
  • Coalmont, BC