DrumminDaddy
Hit it, Baby !!
I had originally started to post some information on the Kenwood Supreme series knob job in another post:
http://www.audiokarma.org/forums/showthread.php?t=602166
Because this is a separate issue from the electronic repair, and because several AK members have expressed some interest in this matter, I've started a thread specifically documenting the knob production.
The goal of this thread is simply to inform those who may have curiosity about machining, how it may be accomplished. The knob, specifically relating to audio restoration, is a fine little piece of machine work in its own right.
As I complete the operations, I will post more information along with my thought processes. As you might imagine, there can be more than one way to accomplish the same results depending on the machine and tooling available.
Because this knob is not only a functional element, but visually appealing as well, considerations will be made regarding surface finish. In other words, I am going to select my tooling and machining processes to faithfully reproduce the tool marks that comprise the finish as close as I can. I will add examples with photos as I get to this point to better illustrate this concept.
The first step in the process is to reverse engineer the original part. Exacting measurements are taken and these dimensions will be used to create a program for a CNC machine tool (computerized numerical control).
A CNC machine is a machine tool with servo driven axes. There are a multitude of configurations available today. In my shop, however, my choices are a bit more limited.
The axes of these machines are astonishingly accurate. It is commonplace for a machine to be able to maintain repeatability to .0002 inches. To put that into perspective, a human hair is about .002 inches in diameter. So we're talking positional accuracy that is ten times thinner than a human hair. This finesse in accuracy is complemented with some considerable muscle. I can place a piece of carbon steel in a lathe with a 12 inch chuck and easily reduce its diameter by 1/2 inch in a single pass. The manufacturing world has many specialized machines and tooling. We're just going to take a peek at what we can accomplish to make our love for audio just that much more rewarding.
Some basic measuring techniques using calipers, surface plate/height gage and radius gages.
I also measure the shaft of an aftermarket speaker select switch for my
700m. This shaft has a slightly larger diameter than the original. Therefore, the hole in the knob that recieves the shaft shall be made to fit this larger size. I will also make some that will fit the original diameter as well because I have a 700T that is missing a knob.
http://www.audiokarma.org/forums/showthread.php?t=602166
Because this is a separate issue from the electronic repair, and because several AK members have expressed some interest in this matter, I've started a thread specifically documenting the knob production.
The goal of this thread is simply to inform those who may have curiosity about machining, how it may be accomplished. The knob, specifically relating to audio restoration, is a fine little piece of machine work in its own right.
As I complete the operations, I will post more information along with my thought processes. As you might imagine, there can be more than one way to accomplish the same results depending on the machine and tooling available.
Because this knob is not only a functional element, but visually appealing as well, considerations will be made regarding surface finish. In other words, I am going to select my tooling and machining processes to faithfully reproduce the tool marks that comprise the finish as close as I can. I will add examples with photos as I get to this point to better illustrate this concept.
The first step in the process is to reverse engineer the original part. Exacting measurements are taken and these dimensions will be used to create a program for a CNC machine tool (computerized numerical control).
A CNC machine is a machine tool with servo driven axes. There are a multitude of configurations available today. In my shop, however, my choices are a bit more limited.
The axes of these machines are astonishingly accurate. It is commonplace for a machine to be able to maintain repeatability to .0002 inches. To put that into perspective, a human hair is about .002 inches in diameter. So we're talking positional accuracy that is ten times thinner than a human hair. This finesse in accuracy is complemented with some considerable muscle. I can place a piece of carbon steel in a lathe with a 12 inch chuck and easily reduce its diameter by 1/2 inch in a single pass. The manufacturing world has many specialized machines and tooling. We're just going to take a peek at what we can accomplish to make our love for audio just that much more rewarding.
Some basic measuring techniques using calipers, surface plate/height gage and radius gages.
I also measure the shaft of an aftermarket speaker select switch for my
700m. This shaft has a slightly larger diameter than the original. Therefore, the hole in the knob that recieves the shaft shall be made to fit this larger size. I will also make some that will fit the original diameter as well because I have a 700T that is missing a knob.