The Parallel Node, Calfee

[Vibe]

Bill I understand a lot of what you are saying. Your ideas on how a tuner works were the first I read and as such were the first I took to be correct. After reading a bit more Im not sure I still follow everything you say compared to some of the other explinations out there.

.......
If this is correct I see how it gets ammo of different velocities to leave the barrel at the same parallel line. But is that what you want? I don't think it is.

Here is how I see ammo acting that leaves parallel to the chamber in the parallel node model:

Please point me where I am missing the boat here because I am really having trouble seeing the benefit the parallel node model has when velocity isn't consistent. Maybe velocity is consistent enough in quality ammo that the differences are miniscule, I don't know. I have read a bit and see the points people have that question if a parallel node is physically possible. I know which way I lean on that stance but I want to keep an open mind both ways until I have a firm understanding of both sides of the story.

After reading Varmint Al's stuff I can see how his idea works to minimize the effect velocity changes have on group sizes. If I understand his idea right a correctly set tuner has the average bullet leaving the barrel on the up swing, towards the top of the swing. Leaving towards the top of the swing allows a slower bullet to leave later but at a higher point in the swing which counteracts the extra drop the slower bullet has. A faster bullet leaves earlier at a lower part of the swing. This lower angle gives less rise in the bullets path which the extra speed gives less drop, again counteracting each other. The problem I have with this model is that it assumes the barrel movement is always the same at the same speed and as such a slower bullet leaves at a higher point and a faster one at a lower point. I would think a slower bullet would have a different effect on barrel vibrations that also would have to be taken into account. Maybe it is and I just didn't understand what I read. Varmint Al seems to have gone through a lot of modeling and testing to give the results he has. That said a biased test is no better than an educated guess so until both models are explained a bit better to me I am still up in the air as to what I believe actually happens, if anything.

If when you read "Parallel Node" you mentally replace those words with "Second Order Node" it all gets just a bit easier to deal with. As it puts a solid explaination as to why it's important to use the "center" of that node.
It also gets rid of that pesky bend that can't happen that way as well.
Putting the node at the muzzle eliminates a source of yaw as the bullet leaves the muzzle, what with the sideways component of velocity imparted from the moving barrel.
Nice drawings - I think they are upside down, but they are better than I've done for a forum board posting.

 

[Joe Friedrich]

So be it, but there are choices we make also, especially trying to assume or second guess why someones post is not the right response we are looking for. I enjoy what has been shared here so far and on the center-fire forums, we have no control in what or how someone else decides to post even if they started the thread.

There has been a lot of skepticism due to others calculated data, which makes for a good read and some understanding, and then there are others that will actually go out and test these theories which is great, then there are others who base their "knowing about" from another's data or another's experience. I am not saying this is bad, all I'm stating is test Bill's theory yourself, and come to your own conclusion. If it works great, and if it doesn't at least you will then Know.

Knowing comes from direct experience, not from another's experience or what he or she thinks.

JMHO,
Joe

 

[Cabin Mike]

Rogers Muzzle Device

Here is the picture of Rogers creation. It looks great, a very fine piece of work. As Bill stated he is going to fit this device to one of my guns this morning. I'm hoping to get decent weather this weekend to run it through the paces. I like the concept of this style and I'm excited about seeing how it performs. I will try to give a report as best as I can after the testing is completed.

Mike Sherrill

Rogers new Muzzle Device

 

[Tom C.]

i have a harrel tuner with extra weights

isn't aherns the same thing except with more
choice of weights?

 

[Kathy]

Friend Mike:

Friend Mike:

Thanks for posting the picture....see you shortly..

Friend Tom C: This is Roger's device.....three of the six weights are screwed into the front of the device body....

Your friend, Bill Calfee

 

[Frank Svenson]

Device

Friend Mike:

Thanks for posting the picture....see you shortly..

Friend Tom C: This is Roger's device.....three of the six weights are screwed into the front of the device body....

Your friend, Bill Calfee

Bill
Is this device threaded on or a slip fit?
It appears to have a slot half way thru, is that right? And if so what for? TIA
Frank

 

[Vibe]

Bill
Is this device threaded on or a slip fit?
It appears to have a slot half way thru, is that right? And if so what for? TIA
Frank

Looks like a standard method of clamping onto a shaft - in this case a barrel. The slot is to allow movement of the two clamp wings.

 

[RvA]

Looks like a standard method of clamping onto a shaft - in this case a barrel. The slot is to allow movement of the two clamp wings.

You got it Vibe, Just a clamp on setup. I'm working on a threaded version too.

Roger

 

[Vibe]

Looks good. What are the weights? ID? OD?
Looks different than what I expected. I only see one weight I would say was 1 oz. and only 2 that look like Aluminum. I would have thought that the more aluminum weights you had the faster the node would mover forward (with less weight).
Approx where does the muzzle line up to?

 

[RvA]

Looks good. What are the weights? ID? OD?
Looks different than what I expected. I only see one weight I would say was 1 oz. and only 2 that look like Aluminum. I would have thought that the more aluminum weights you had the faster the node would mover forward (with less weight).
Approx where does the muzzle line up to?

Vibe,

The main body is 5oz and there are 6 weights

1/2oz alum
1oz aulm
2oz ss
3oz ss
4oz ss
5oz ss

The OD on this "device" is 1.55 and the bore is .625. I was going to make the 2oz out of alum but I was trying to keep the overall length down. I may still make up a 2oz out of alum and try that out also.

So far the results looks really promising, but more testing is needed.

Best,

Roger

 

[Vibe]

I'm of the speculative opinion that length will be your friend in this. My only other concern (If you want to call it that) is that the clamp relief slot (unless oriented vertically to one side) may allow too much movement between "tuner" and barrel. I understand the necessity of it though.

Be sure and keep us posted on the results. (Bill would probably like for it to be in a separate thread, and that might not be a bad idea. Since this is post #150 on a thread with 7000 views and 10 pages)

 

[Joe Friedrich]

Roger, very nice. Wishing Mike and yourself the best in your testing.

Take Care,
Joe

 

[Kathy]

My friends

My friends:

Yesterday, Mike Sherrill came to the shop. We carefully bored Roger's tuner to a gage fit to Mike's barrel. MIke will be running tests, maybe, as a giant snow storm is working as I type this, this week-end.

After we got the machine work done Mike and I spent about 30 minutes with his old device (tuner) and Roger's new device, using a test I devised and wrote up in one of my Precision Shooting articles that shows exactly the down force exerted by the device.

You need a scale and a little "Vee" block made of styrofoam, and a string.
You suspend the device at the center of the two clamp screws by the string from the ceiling. You set the front edge of the device on the Vee block, on the scale. This gives you the actual downforce applied by the device. (my scale is a standard 20 lb reading in ounces, fairly course)

An example: The 8 ounce Harrell's device (tuner) exerts about 5 ounces of down force with the adjustment turned to zero.

What has turned out to be extremely interesting is the number of combinations of downforce that can be exerted with Roger's weight system using two different weight materials for the weights. Using the 6 weights Roger supplies in his Harrell's kit, 3 aluminum and 3 steel, Mike has already came up with 400 combinations and counting. So the fear of needing a "fine adjustment" looks like it may just be a fear, although testing will tell for positive.

If one would like to see how critical the weight, and its placement in front of the muzzle is, rig up this little experiment. You will be amazed at how important that the correct placement in front of the muzzle is.

After playing with the device for a while I have got another idea I'm going to discuss with Roger. I'm thinking of what I'll call a spool extension. In other words, a spacer, of aluminum, turned in the shape of a spool, to make it as extremely light as possible. This will be used, I invision, as the first screw in at the front of the device. They could be various lengths...then one could place single, small weights, at various distances from the device, gain major downforce, but keep the overall device weight very small to help make 10 1/2 pound weight.

Finally, I type this on Friday 3/7/08....as Mike left I gave him 40 rounds of ammo and requested that if he gets Roger's device working, to shoot an ARA card with those 40 rounds.

Mike said he will make a report, good or bad as soon as he can.

Your friend, Bill Calfee

 

[Vibe]

Bill
I've been doing a few moment calculations on the weights you and Roger have mentioned, and have come to some very surprising results. That being that you may never need the steel weights,the steel just confuses the incremental adjustment order and the aluminum does a much faster job of increasing the reaction moment, your spool could do even better, though if it were me, rather than a smaller diameter for the center of the "spool" I would take the material from the ID and hollow it out. It would be much stiffer that way.
I really like the direction this is going and am excited to see what the results are.
That being said, you know there is another discussion going on pertaining to another school of thought - that of tensioned barrels. Studying both methods I came to some interesting (to me) conclusions. See what you and the other posters think about these thoughts.

Muzzle device - Modifies the barrel/muzzle timing such that it reduces the vertical dispersion caused by velocity differences. But it doesn't really do a lot for bullet yaw.

Tensioned barrel - intended to remove the "sag" from the "at rest" barrel, which removes much of the driving force that causes the major barrel harmonics. As such these do not allow velocity compensation, but would tend to reduce bullet yaw as it leaves the barrel.

Now what would happen if one were to incorporate both ideas into a tensioned muzzle device? Say make the "tuner" attachment in such a way that the last 4-6" were tensioned - this should better force the last few inches of barrel to be linear (like you would like it to be), yet still allow the harmonics to move the barrel into a velocity compensating position with the correct mass placement.

There is the issue of the (usually aluminum) tensioning tube expanding faster/more than the steel barrel due to temp changes, but this can be addressed with a system of Belleville washer springs. Which would level out the tension changes due to temp changes. As for the attachment system - to maintain alignment and remain stiff, look into the system used by B-Loc and Ringfedder in their shaft clamps and hubs - though one would have to use a torque wrench when mounting these as they could easily reduce the bore if overtightened.

Just some rambling thoughts on the progressing developments.

 

[BigMacky]

My friends:

Yesterday, Mike Sherrill came to the shop. We carefully bored Roger's tuner to a gage fit to Mike's barrel. MIke will be running tests, maybe, as a giant snow storm is working as I type this, this week-end.

After we got the machine work done Mike and I spent about 30 minutes with his old device (tuner) and Roger's new device, using a test I devised and wrote up in one of my Precision Shooting articles that shows exactly the down force exerted by the device.

You need a scale and a little "Vee" block made of styrofoam, and a string.
You suspend the device at the center of the two clamp screws by the string from the ceiling. You set the front edge of the device on the Vee block, on the scale. This gives you the actual downforce applied by the device. (my scale is a standard 20 lb reading in ounces, fairly course)

An example: The 8 ounce Harrell's device (tuner) exerts about 5 ounces of down force with the adjustment turned to zero.

What has turned out to be extremely interesting is the number of combinations of downforce that can be exerted with Roger's weight system using two different weight materials for the weights. Using the 6 weights Roger supplies in his Harrell's kit, 3 aluminum and 3 steel, Mike has already came up with 400 combinations and counting. So the fear of needing a "fine adjustment" looks like it may just be a fear, although testing will tell for positive.

If one would like to see how critical the weight, and its placement in front of the muzzle is, rig up this little experiment. You will be amazed at how important that the correct placement in front of the muzzle is.

After playing with the device for a while I have got another idea I'm going to discuss with Roger. I'm thinking of what I'll call a spool extension. In other words, a spacer, of aluminum, turned in the shape of a spool, to make it as extremely light as possible. This will be used, I invision, as the first screw in at the front of the device. They could be various lengths...then one could place single, small weights, at various distances from the device, gain major downforce, but keep the overall device weight very small to help make 10 1/2 pound weight.

Finally, I type this on Friday 3/7/08....as Mike left I gave him 40 rounds of ammo and requested that if he gets Roger's device working, to shoot an ARA card with those 40 rounds.

Mike said he will make a report, good or bad as soon as he can.

Your friend, Bill Calfee

Bill,

Here's how I did my downward force testing .....

I cut a piece of dowel that was 1" longer than my barrel measured from the action to the crown. I then drilled a hole in the dowel in 1" from the end (I now had a "lever" that measured the same as the length of my barrel. I put a metal pin through the hole and held it between the jaws of a vise (this is now the pivot point) and I attached the Tuner to the other end.

At the tuner end I placed a postage scale that supported the assembly right at the end of the barrel. The point of contact was very thin, so basically it would measure the true downward force on the barrel at the crown TAKING INTO ACCOUNT THE BARREL LENGTH. My thought was that the length of the ""lever" might matter.

I set the tuner to 0 and then "zeroed" the scale .... I could then measure whatever I wanted ... as I moved the tuner out to 500 I could see the exact "DELTA" in downward force the was exerted by an increment in the tuner scale..

Not sure if this was the "right" approach, but that's how I went about it. I could also move the point of contact for the scale out to the end of the tuner and move it outwards as I changed the setting if that would make more sense. I'm not sure which is "better" or more "relevant"

Fred

 

[RLHBUSL]

Possible Combinations

Bill,

By changing the sequence in which the weights are installed, there are 720 possible combinations that can be created with 6 different weights - if all the weights are used. There are 872 possible combinations if you use less than all the weights.

Ryan

 

[BigMacky]

If we are talking about Rogers weights the small aluminum 1/2 pounce one is made to only attach to the end ....

Fred

 

[RLHBUSL]

Fred

If I understand you correctly, there is an aluminum 1/2 oz weight that MUST be used (and must be on the end) and there are 5 additional weights (2 aluminum and 3 steel) that may or may not be used and can be used in any order. If this is true, I believe there are only 152 possible combinations available.

 

[RLHBUSL]

The combinations that include less than all the available weights are ADDITIONAL possibilities. For example, you have 720 possible combinations with 6 weights and 120 possible combinations with 5 weights, so using 5 OR 6 weights you have 840 possible combinations. Hope this makes sense.

Ryan

 

[Vibe]

If I understand you correctly, there is an aluminum 1/2 oz weight that MUST be used (and must be on the end) and there are 5 additional weights (2 aluminum and 3 steel) that may or may not be used and can be used in any order. If this is true, I believe there are only 152 possible combinations available.

In the calculations I've run on some of the various combinations, the mixing of the steel and aluminum weights does not result in even steps from one combination to the next - there are some fairly substantial "gaps", and some of those results were a bit surprising, like a 2oz aluminum mass having more effect than a 3oz steel one. And on continuation of those calculations (Moments about the muzzle) - staying with just Aluminum always produced the greater moment - always due to it's greater distance of centroid (Center of mass) to muzzle. The proof will be in the shooting, but I strongly suspect that this will become apparent even then.