Here's some questions for you repair guys :
1)Did Mr.Oberloh create new pistons or did he rebuild the old ones ?
2) If he did make new ones how did Mr. Oberloh know where to place the holes in the new pistons and how did he go about drilling them out ?
3) I have noticed that on some valves the hole are not straight through but may have a curve to them . Also, they are not all perfectly smooth,some have a bump in the wall of the bore . How does he achieve that ?
Rebuilding Valves
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oldbandnerd
- 5 valves
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Daniel C. Oberloh
- pro musician
- Posts: 547
- Joined: Fri Mar 19, 2004 9:22 pm
- Location: Seattle Washington
The valves shown on the page are the original Holton 345 pistons. I removed the tops and made new replacements in order to make the desired alterations. I do occasionally make replacement pistons but try to avoid it when I can. Its a lot of work.
To answer your questions:
The construction of a piston is done by drilling/milling the holes in a tube that will eventually be the body of the piston. This is done on a vertical milling machine that is equipped with a special fixture that holds the piston in the exact position so it can be accurately drilled. I will use an indexing fixture or a dividing head fixture to hold such a part as it is not cost effective to make custom tooling for a one off job. The way I go about knowing where to put the holes/ports are to be placed is by observation and careful measuring of the cylinder casing and adjacent pistons.
Once the holes are completed, thin walled brass tubes that are pre bent are worked into the and thru the proper ports where a steel ball is then pushed thru to round out the ports. The ports are then hard soldered or brazed into place. The valve is then turned, ground and honed to the desired diameter. Because the ports are larger in diameter then the piston body can accommodate, when they cross in close proximity a compromise is made and that is done by creating a dent in the port that will allow just enough clearance for the ports to pass one another.
I hope this helps answer your questions.
Daniel C. Oberloh
Oberloh Woodwind and Brass Works
www.oberloh.com
To answer your questions:
The construction of a piston is done by drilling/milling the holes in a tube that will eventually be the body of the piston. This is done on a vertical milling machine that is equipped with a special fixture that holds the piston in the exact position so it can be accurately drilled. I will use an indexing fixture or a dividing head fixture to hold such a part as it is not cost effective to make custom tooling for a one off job. The way I go about knowing where to put the holes/ports are to be placed is by observation and careful measuring of the cylinder casing and adjacent pistons.
Once the holes are completed, thin walled brass tubes that are pre bent are worked into the and thru the proper ports where a steel ball is then pushed thru to round out the ports. The ports are then hard soldered or brazed into place. The valve is then turned, ground and honed to the desired diameter. Because the ports are larger in diameter then the piston body can accommodate, when they cross in close proximity a compromise is made and that is done by creating a dent in the port that will allow just enough clearance for the ports to pass one another.
I hope this helps answer your questions.
Daniel C. Oberloh
Oberloh Woodwind and Brass Works
www.oberloh.com
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oldbandnerd
- 5 valves
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- Joined: Wed Dec 22, 2004 8:43 pm
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pulseczar
- 3 valves
- Posts: 435
- Joined: Tue Sep 27, 2005 2:03 am
Well said. I'm still blown away by the technical terms, but in a few hours I will decipher it and be in even more awe. Dan, you kick @ss!UncleBeer wrote:Sorry; that quote's from Arthur C. Clarke.iiipopes wrote:"Any sufficiently advanced technology is indistinguishable from magic." - Robert Heinlein.
/geek mode off