Posted: 30 Apr 2021 12:00 pm
Jim,
I agree on the sum total view of the playability. I think that those who have the good fortune to have a coherent elasticity spread uniformly throughout their instruments will probably have the best playing most responsive instruments. That would be difficult to plan for though, I would think. I like the saw analogy
I think you are probably right with the roller nut hysteresis thing. I'm using a hardened 1/8 axle. It would be intersting after I'm rolling to compare it to a 1/16 axle. 1/8" spacers would be easy to make. I think I probably may do better with chrome plating for an even slipperier surface. Some of the surface treatments they put on carbide cutters are very slippery. I've not seen just coated rounds. They may be available though. I'll save that for later for small improvements just for kicks.
Thinking about it just now, it strikes me that if the nut were to lie on a node point, you may have greater hysteresis than if the nut were on a point of maximum vibration. If you have table salt sprinkled on an inclined plane that's not too slanted it will just sit there. If you then put a little ultrasonic or other vibration on the plane, the salt will just slip down the inclined plane as if the friction were not there. I guess you could test the idea by just putting a little ultrasonic on the nut and see if anything changes. Just for curiosity though. I wouldn't expect to change much based on that.
Paddy,
I may have some spares after the project is done that I could part with. My process was troublesome though because it seems like no matter how many tools you have, you always need a new one to make the work go accurately with speed. I did it the slow way due to not wanting to spend money on tools that I would only use once. I can envision making em in almost one or two passes, but that would require better cutters and a little saw. I think some effective surface conditioning like a tumbler with the proper media would be a nice addition to make em look a little more like downtown. I notice that some pics of other bellcranks look like they were conditioned with a nice process. I turned the edges over by hand in the ones I made. They look OK but I think a more mechanized process would make em look a bit better.
Jack
Interesting that you remember about the machined changer finger holes. I machined mine a thousanth or so small and then lapped them on the lathe with a close fitting dowel wrapped with fine silicone carbide paper until just right, same with the raise/lower levers. Probably overkill but they're done now and they fit slicker than a greased weasel.
Jack and JD
You are both absolutely correct about the cast aluminum parts vs machined. I would have loved to have been able to get a foundry to cast me up some parts. I even talked to a foundry that would have done it at reasonable cost. However making the model and the running arround, making sure the alloy was right, training the foundry staff on my specs, the risk of the learning curve, and all the other time issues and cost just made me decide on machining. I agree though, cast is no doubt better. It's less damping.
I had an interesting experience. I mistakenly turned the spindle backwards when drilling a 5/16 hole in T6 Aluminum which is the alloy for the end plates. The drill went halfway through backwards before I could catch it and stop the process. When I manually filed the defect off the piece to clean it up and continue on past the error, the metal was unbelievablebly more rigid. From that I deduce that the original T6 temper would have substancially more damping than in the unhardened condition.
I think you're right. I'm most probably taking a hit on the response and playability because of the machined vs cast pieces. I would be tickled to death to get anywhere near the Franklin experience. That may have to wait just a little bit longer though.
Bobby
Excellent suggestion about the plastic and decorations. I'm thinking that I'll do that or something similar. I think I'll probably just use wood. I like your pic. Excellent project I know what you went through. I'm having a blast. Do you have a post mentioning this project and more of the details that you can post here? I'd be interested in the features that you built into your PSG. I have a dynosaur CNC. I can imagine that manual milling would be a bit more time consuming. However it's possible to waste a lot of programming time on one off milling projects. I'm not sure which is faster now that I think about it. This is the largest metal machining project that I've done so my experience with machining isn't that extensive. I learned quite a bit.
Hi Sonny
I have 30 years violin/related instruments repair experience, 10 years exclusive violin making, 2 or 3 years pattern making to assist a blow mold shop, lots of reading in physics and a bit of math, always played piano and violin throughout improving very slowly to what I would say is about an upper intermediate level presently. If the good Lord tarries and I don't finally kick the bucket too awfully soon, I may have just barely scraped the lowest level of advanced. By then of course, I'll be about 110. I'll never be great, I don't have the talent for it but I enjoy it. I played dobro in a bluegrass band for about 5-6 years with the last gig about 6 years ago. The machining came sideways through the violin making experience making jigs fixtures etc. The best word describing me I think was the last one you employed... "savant". My wife says "idiot" savant. Although if you leave off the savant part it would come closer to the truth. Just kidding. My wife is teriffic. She encourgaged me in the pedal steel project and is enthusiastic about all my activities.
Regards DM
I agree on the sum total view of the playability. I think that those who have the good fortune to have a coherent elasticity spread uniformly throughout their instruments will probably have the best playing most responsive instruments. That would be difficult to plan for though, I would think. I like the saw analogy
I think you are probably right with the roller nut hysteresis thing. I'm using a hardened 1/8 axle. It would be intersting after I'm rolling to compare it to a 1/16 axle. 1/8" spacers would be easy to make. I think I probably may do better with chrome plating for an even slipperier surface. Some of the surface treatments they put on carbide cutters are very slippery. I've not seen just coated rounds. They may be available though. I'll save that for later for small improvements just for kicks.
Thinking about it just now, it strikes me that if the nut were to lie on a node point, you may have greater hysteresis than if the nut were on a point of maximum vibration. If you have table salt sprinkled on an inclined plane that's not too slanted it will just sit there. If you then put a little ultrasonic or other vibration on the plane, the salt will just slip down the inclined plane as if the friction were not there. I guess you could test the idea by just putting a little ultrasonic on the nut and see if anything changes. Just for curiosity though. I wouldn't expect to change much based on that.
Paddy,
I may have some spares after the project is done that I could part with. My process was troublesome though because it seems like no matter how many tools you have, you always need a new one to make the work go accurately with speed. I did it the slow way due to not wanting to spend money on tools that I would only use once. I can envision making em in almost one or two passes, but that would require better cutters and a little saw. I think some effective surface conditioning like a tumbler with the proper media would be a nice addition to make em look a little more like downtown. I notice that some pics of other bellcranks look like they were conditioned with a nice process. I turned the edges over by hand in the ones I made. They look OK but I think a more mechanized process would make em look a bit better.
Jack
Interesting that you remember about the machined changer finger holes. I machined mine a thousanth or so small and then lapped them on the lathe with a close fitting dowel wrapped with fine silicone carbide paper until just right, same with the raise/lower levers. Probably overkill but they're done now and they fit slicker than a greased weasel.
Jack and JD
You are both absolutely correct about the cast aluminum parts vs machined. I would have loved to have been able to get a foundry to cast me up some parts. I even talked to a foundry that would have done it at reasonable cost. However making the model and the running arround, making sure the alloy was right, training the foundry staff on my specs, the risk of the learning curve, and all the other time issues and cost just made me decide on machining. I agree though, cast is no doubt better. It's less damping.
I had an interesting experience. I mistakenly turned the spindle backwards when drilling a 5/16 hole in T6 Aluminum which is the alloy for the end plates. The drill went halfway through backwards before I could catch it and stop the process. When I manually filed the defect off the piece to clean it up and continue on past the error, the metal was unbelievablebly more rigid. From that I deduce that the original T6 temper would have substancially more damping than in the unhardened condition.
I think you're right. I'm most probably taking a hit on the response and playability because of the machined vs cast pieces. I would be tickled to death to get anywhere near the Franklin experience. That may have to wait just a little bit longer though.
Bobby
Excellent suggestion about the plastic and decorations. I'm thinking that I'll do that or something similar. I think I'll probably just use wood. I like your pic. Excellent project I know what you went through. I'm having a blast. Do you have a post mentioning this project and more of the details that you can post here? I'd be interested in the features that you built into your PSG. I have a dynosaur CNC. I can imagine that manual milling would be a bit more time consuming. However it's possible to waste a lot of programming time on one off milling projects. I'm not sure which is faster now that I think about it. This is the largest metal machining project that I've done so my experience with machining isn't that extensive. I learned quite a bit.
Hi Sonny
I have 30 years violin/related instruments repair experience, 10 years exclusive violin making, 2 or 3 years pattern making to assist a blow mold shop, lots of reading in physics and a bit of math, always played piano and violin throughout improving very slowly to what I would say is about an upper intermediate level presently. If the good Lord tarries and I don't finally kick the bucket too awfully soon, I may have just barely scraped the lowest level of advanced. By then of course, I'll be about 110. I'll never be great, I don't have the talent for it but I enjoy it. I played dobro in a bluegrass band for about 5-6 years with the last gig about 6 years ago. The machining came sideways through the violin making experience making jigs fixtures etc. The best word describing me I think was the last one you employed... "savant". My wife says "idiot" savant. Although if you leave off the savant part it would come closer to the truth. Just kidding. My wife is teriffic. She encourgaged me in the pedal steel project and is enthusiastic about all my activities.
Regards DM