Re: Re: Re: Re: vented vs leaky


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Posted by Rick Denney on October 22, 2003 at 13:44:33:

In Reply to: Re: Re: Re: vented vs leaky posted by js on October 22, 2003 at 12:23:52:

The quarter inch would depend on the size of the gap machined into the rotor between the two ports. On some tubas, a quarter inch might see brass instead of air. It's easy to tell by looking at the rotor, which of course should be removed for the procedure so you can clean out the filings.

But drilling them off-center is a really good idea and I wish I'd done that on my Miraphone. It keeps the vent hole as far as possible from the edges of the ports, which helps prevent leakage. If I ever have leakage, I'll fill the hole and redrill it off-center.

Mary Ann, take a look at your 184. At least some CC Miraphones are vented from the factory. If you see a small hole in the casing between the valve-tube ports, then those are the vents. Many folks mistake these for oil ports, thought they do work for that purpose.

Rick "who mounted a standard 1/16 drill bit in a tiny pin vise and spun it between his fingers to drill the hole" Denney


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