S
ShelleyDavidson
Guest
Since Gene has announced his tuner design, I figured I'd talk about the one that I'm building. The design work on this tuner was done by Esten Speers who is a retired vibration engineer with the input and computer modeling of Varmint Al. Also, there was a significant amount of help and input by Ralph Stewart who lent his own brand of high frequency energy and research abilities to the project and made a couple of trips to the Odessa tunnel to test the tuner and effects of DA, all under the watchful eyes of Gene Beggs. Me, I was the machinist on the project and the only real design change that I made was to increase the diameter of the hole and funnel section that extends past the front of the barrel. The increased hole size was to minimize any possible turbulence inside the tuner. And yes, my Oehler 35 chronograph does work quiet well with the tuner. This is the design that was hashed out right here on BR.Com.
I have just finished my first run of 20 tuners and will have the laser engraved weight rings back from the shop later this week. The perceived benefits of the tuner that I make are:
The tuner was engineered so the mass (6 oz.) will assist in dampening the jitters, or wild vibrations, and tune the lower frequency vibrations that are so important to counteract the variances in DA during a day of shooting.
My tuner consists of one cnc'd tuner body that screws on a .9 diameter 32tpi one inch threaded section of the muzzle and two weights that screw over the part of the tuner that hangs off the end of the muzzle. The threaded section, where the weights are is also 32tpi which seems to go through a complete tune cycle or node about every .050" or thereabouts. I assume that different guns and calibers will have slightly different DA formulas and different nodes just like different calibers tune differently when using powder. After all, we are still addressing the exact same dynamics as when using powder to tune.
I didn't farm my tuner out, the body is made on my own cnc lathe and the weights are made on my 16X40 barreling lathe using one set-up from start to finish so they are as concentric as a cnc'd ring. The weight ring's diameter is too big for my cnc which utilizes 5C collets. There is no change in the point of impact using this tuner.
How much is my price? Quiet a bit more than Gene's I'd think. One of the rings has graduations laser etched on it so as to help in setting and getting back to the same spot when needed. For the first batch, the etching is costing me right at $20.00 each. There's a set up charge involved but even after the first time that cost will still be a factor. Then, there's tooling and the time to write and de-bug around 400 lines of code for the tuner. If I knew cad, I could probably use it to write my programs but I don't so I still write in raw G-codes and create my own sub-routines. Oh, yeah, I broke $75.00 worth of mini boring bars before getting the programing right. I didn't say I was a good programmer. (grin) I've actually been working on getting this going for a month and a half.
I can say that my tuners work well. For instance, I was at the range last Saturday. Because it was chilly and really windy I took a break in the heated stat shack and enjoyed a 45 minute BS session. When I returned to the line I checked the DA meter which had risen 500 feet while I was away. I moved my tuner 1/8 turn back towards the rear of the rifle and shot a .150" five shot group. I kinda lucked out on that group as the wind was switchy and gusting to about 20mph. I also shot some wide groups. But I shot the same Harrel's Power Measure setting that I'd used the previous Saturday when it was t-shirt weather, and I stayed in tune all day.
This was kinda interesting because it also tied in with another experiment. I like 30 calibers. I've shot some really small groups with a 30BR using Benchmark, but you can't get enough Benchmark in a BR case to get to the sweet spot muzzle velocity of 2980 fps that the 118 bullets do well at. I've actually shot a .045" group and a .083" group in registered matchs at Tomball using Benchmark. I wanted to try tuning a case to a certain powder.... namely Benchmark. So I had Dave Kiff make a 30BRX reamer that is simply a regular 30BR reamer with the shoulder run forward .100". Nothing new here. Then my testing showed that to chronograph 2980 fps in chilly weather I needed more Benchmark so I ran the reamer in another .025" so I now had a .125" long 30BR. When I got to the sweet spot speed wise I then moved my tuner twice at 1/8 turn per move and was in tune. Neat!!!!
Will my tuner work better or worse than Gene's? Darned if I know. All I know is that I've been dinking around with tuners for several years and they all seemed to work but I had no idea how to use them because I didn't understand the dynamics of how they worked. In a nut shell, here's how it works. When the day warms up and the humidity falls, the air gets lighter/ less dense and your bullet will reach the muzzle a bit quicker. So, you can either decrease your powder load to slow the bullet so it reaches the muzzle at the same point in it's vibration swing or you can turn the tuner so that it's weight moves back towards the rear. This increases the vibration frequency so the muzzle reaches the same sweet spot quicker, when the faster moving bullet reaches it. The tuner weight affects the barrel like the weight on a pendulum. Increase the distance from the fulcrum to the weight on a pendulum and the swing slows down. Go shorter and the pendulum's swing speeds up. It's just that simple.
I have just finished my first run of 20 tuners and will have the laser engraved weight rings back from the shop later this week. The perceived benefits of the tuner that I make are:
The tuner was engineered so the mass (6 oz.) will assist in dampening the jitters, or wild vibrations, and tune the lower frequency vibrations that are so important to counteract the variances in DA during a day of shooting.
My tuner consists of one cnc'd tuner body that screws on a .9 diameter 32tpi one inch threaded section of the muzzle and two weights that screw over the part of the tuner that hangs off the end of the muzzle. The threaded section, where the weights are is also 32tpi which seems to go through a complete tune cycle or node about every .050" or thereabouts. I assume that different guns and calibers will have slightly different DA formulas and different nodes just like different calibers tune differently when using powder. After all, we are still addressing the exact same dynamics as when using powder to tune.
I didn't farm my tuner out, the body is made on my own cnc lathe and the weights are made on my 16X40 barreling lathe using one set-up from start to finish so they are as concentric as a cnc'd ring. The weight ring's diameter is too big for my cnc which utilizes 5C collets. There is no change in the point of impact using this tuner.
How much is my price? Quiet a bit more than Gene's I'd think. One of the rings has graduations laser etched on it so as to help in setting and getting back to the same spot when needed. For the first batch, the etching is costing me right at $20.00 each. There's a set up charge involved but even after the first time that cost will still be a factor. Then, there's tooling and the time to write and de-bug around 400 lines of code for the tuner. If I knew cad, I could probably use it to write my programs but I don't so I still write in raw G-codes and create my own sub-routines. Oh, yeah, I broke $75.00 worth of mini boring bars before getting the programing right. I didn't say I was a good programmer. (grin) I've actually been working on getting this going for a month and a half.
I can say that my tuners work well. For instance, I was at the range last Saturday. Because it was chilly and really windy I took a break in the heated stat shack and enjoyed a 45 minute BS session. When I returned to the line I checked the DA meter which had risen 500 feet while I was away. I moved my tuner 1/8 turn back towards the rear of the rifle and shot a .150" five shot group. I kinda lucked out on that group as the wind was switchy and gusting to about 20mph. I also shot some wide groups. But I shot the same Harrel's Power Measure setting that I'd used the previous Saturday when it was t-shirt weather, and I stayed in tune all day.
This was kinda interesting because it also tied in with another experiment. I like 30 calibers. I've shot some really small groups with a 30BR using Benchmark, but you can't get enough Benchmark in a BR case to get to the sweet spot muzzle velocity of 2980 fps that the 118 bullets do well at. I've actually shot a .045" group and a .083" group in registered matchs at Tomball using Benchmark. I wanted to try tuning a case to a certain powder.... namely Benchmark. So I had Dave Kiff make a 30BRX reamer that is simply a regular 30BR reamer with the shoulder run forward .100". Nothing new here. Then my testing showed that to chronograph 2980 fps in chilly weather I needed more Benchmark so I ran the reamer in another .025" so I now had a .125" long 30BR. When I got to the sweet spot speed wise I then moved my tuner twice at 1/8 turn per move and was in tune. Neat!!!!
Will my tuner work better or worse than Gene's? Darned if I know. All I know is that I've been dinking around with tuners for several years and they all seemed to work but I had no idea how to use them because I didn't understand the dynamics of how they worked. In a nut shell, here's how it works. When the day warms up and the humidity falls, the air gets lighter/ less dense and your bullet will reach the muzzle a bit quicker. So, you can either decrease your powder load to slow the bullet so it reaches the muzzle at the same point in it's vibration swing or you can turn the tuner so that it's weight moves back towards the rear. This increases the vibration frequency so the muzzle reaches the same sweet spot quicker, when the faster moving bullet reaches it. The tuner weight affects the barrel like the weight on a pendulum. Increase the distance from the fulcrum to the weight on a pendulum and the swing slows down. Go shorter and the pendulum's swing speeds up. It's just that simple.
