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Old 03-31-2014, 08:21 PM
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Default Gas Spud Orifices

I have a job in Vermont that needs the gas spud configuration changed to try to control a combustion rumble. The existing spuds now are a straight piece of 3/8" pipe, I'm going to have to enlarge the hole that the spud passes through the air diffuser, then screw a forged 3/8" cap on the spuds, that have holes drilled into the side. When orientated in the correct position, the gas will be injected into the air flow to change the mixture and the combustion, hopefully changing the harmonic that causes the combustion rumble. Between the 2 boilers I had to modify 50 caps

When the caps arrived, it was instantly apparent that either the company ordered them wrong or the supplier didn't heed our instructions. Forged caps can come in two different configurations, with a very thick top or a thin top. We had ordered thin and got thick. Not a job killer, but adds a step, that requires lathe work.

I had to put each cap into the chuck of the lathe, then using a 1/2" end mill in a tailstock chuck, then cut the top thickness from 9/16" to 1/8". After this is done with a centering jig in the drill press, the cap had (2) 1/4" hole drilled into the side of the cap, 1/4" down from the top of the cap, roughly 45 degrees from each other.

1 - the caps, the modified one on the left, the one on the right, as it came from the supplier
2 - in the chuck
3 - end mill in the chuck, with washers, stacked on it to control the depth of cut.
4 - the drill press set up
5 - gas holes in the cap, they are now ready to be installed
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Old 03-31-2014, 08:37 PM
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GNAP - Great God of Steam,

Is the rumble just annoying or can it have damaging effects on the boiler?
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Old 03-31-2014, 08:43 PM
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Quote:
Originally Posted by platypus20 View Post
3 - end mill in the chuck, with washers, stacked on it to control the depth of cut.
Precision washers, I presume?
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Old 03-31-2014, 09:03 PM
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Like the end mill trick
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Old 03-31-2014, 09:09 PM
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Quote:
Originally Posted by Shade Tree Welder View Post
GNAP - Great God of Steam,

Is the rumble just annoying or can it have damaging effects on the boiler?
Can be both, in this case, the stack vibrates so badly, that the windows in the plant control room shake.

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Originally Posted by cutter View Post
Precision washers, I presume?
1/2" grade 8 SAE flats
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Old 03-31-2014, 09:43 PM
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How do you stop the end mill from spinning in a Jacobs chuck?
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Old 03-31-2014, 09:53 PM
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Do the depth control washers interfere with chip flow? How are the chips removed from the hole?
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Old 04-01-2014, 08:09 AM
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Quote:
Originally Posted by milomilo View Post
How do you stop the end mill from spinning in a Jacobs chuck?
just tighten it down and don't go crazy on the feed rate.

Quote:
Originally Posted by camdigger View Post
Do the depth control washers interfere with chip flow? How are the chips removed from the hole?
no, although I'm cutting (milling/drilling) about 7/16" in depth, it produces a lot of chips, so I back it out and clean off the end mill about 3-4 time on each cap. So as not wanting to break the end mill, or have it turn in the drill chuck.
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