Rod Frequency Measurement

[Magnus]

 

I know Bill very well - resist his lure, he's a big time polemicist  -  he and I have worked and talked a lot about CCS - I use a lot of his methods. NOT CCF. (Bill's a cranky old guy - he and I get along well.)

Have a look at http://www.sexyloops.co.uk/cgi-bin/theboard_07/ikonboard.cgi?act=ST;f=5;t=7326;st=0;&#entry124974
Grunde is a physics Post Doc in Norway - he and Jason Borger collaborate on casting science articles.

or http://home.att.net/~slowsnap/calib5.htm

If you can find articles by Greg Spolek - he published the most recent stuff on rod frequency.

[Wildfisher]

The loops link is interesting. Must say though I am highly sceptical about measuring frequency by counting with a stop watch (Dr. Bill uses that too). At best it is going to be an approximation. I was not impressed with Dr. Bill's method for frequency but without specialist gear it would not otherwise be easily done. The paper was good though, explains things reasonably clearly.

[Magnus]

Bill's a very interesting guy. He came up with CCS - then published articles which included some wild statements. The arguments about the validity of his system lasted for years - I've been on both side of the fence. I still disagree with some of his ideas.

I've tried counting an oscilating rod and it can be done but isn't exact or easy - easier with a load on the tip. BUT bill varies the load by the stiffness of the rod not by the makers line-weight - that creates a very skewed set of results. It would mean I take a TCR #6 and BIIx #6 and apply two or three times as much mass to the tip of the TCR - but I cast both with lines that weigh the same.
That idea comes from Bill's argument that all #6 rods (or whatever wt rods) should be the same stiffness and rated for casting 30ft of line. His knowledge of casting lets him down - if I can false cast 30ft of line with a rod I can cast a fly from my toes to around 90ft.

[Wildfisher]

Results with new detector, modified firmware and improved (but still shit-useless) clamping

Daiwa Whisker WHITE  10' 3pc, #7    2.16 Hz

Daiwa Whisker RED 10' 3pc, #7    2.25Hz

Vision 3 Zone 10' 3pc #5   2.46Hz

Snowbee Zircon 10' 3pc #5  2.42Hz

Bloke 9' 4pc #6      2.88Hz

March Brown "Baden Powell Special" travel rod,  8 ?',  7pc, #5  2.98Hz

1968 Milbro Tru-fly "dry fly special" – 8 ? ' 2 pc glass, metal ferrule    2.18Hz

All these measurements  are reliably  repeatable within 0.02 Hz

I get variations of around 0.02 by rotating the rod 90 deg. This however is meaningless until we get the clamping sorted out. There is visible parasitic  movement at the handle, especially with the stiff rods where it is very obvious. This will have a dampening effect and reduce the frequency reading.


What really needs doing now is:

Getting the clamping sorted out is priority one. Writing some software to make recording easier. This will also require a firmware change.

Errors introduced by the counting method used in the firmware are negligible.  At 3 hz  (3.000723) a +2 count error would change the reading to 3.000703. We don't measure  at that precession (we could but it's probably not a great idea)  Error could be caused by the detector, but until we get a firm clamping method we won't know if there is an issue as I  suspect most of the variation I am measuring (+ - 0.02 max over several repeats) comes from bad clamping.

By the way Magnus, I have no problems with any of your other contacts inputting to this. Just let me know and I'll let them in.

[Magnus]

Lets see if I post and image 

errrr no - aha additional options

I'll speak to Kevin about having something like this made. Ideally it needs that level of adjustment. A clamp at the front and on the seat allows the rod to flex between the clamp points - if the whole thing is clamped the frequency rises.

[Wildfisher]

Magnus,

Is that the clamping rig the Norwegians are using?  I wonder where the best  clamp point  would  be? Might not the grip position on the handle better represent the way the rod will be used in real life?

[Magnus]

Fred

So long as we have a standardized way to clamp rods and the results we get compare meaningfully with those collected in Norway or the US I'd be happy. There's little about measuring that represents what we do when casting.

[Wildfisher]

I have written PC software to make acquisition of the frequency data easier and saveable. It just connects to the controller with a serial lead. The data can be saved as a csv file which means it can be loaded into a spread sheet like MS Excel later if need be. It also plots the data directly  if you so wish.

We are not far from being  ready to do some real tests now, I bought two big G-clamps the other day, so all I have to do now is get a test set up organised. I'll let you know how that progresses.

Here is a screen-shot with a plot from a Daiwa Whisker. The numbers on the x axis are the number of (equal sized) pieces of insulating tape that were applied to the tip to vary the load. Not very scientific as I have not a clue what one piece of tape weighs, but it illustrates the concept and proves it works..

[attachimg=1]

[Magnus]

Excellent Fred.

I'm away to a publicity thing this weekend, be back on monday.

Be careful with G clamps on cork - I nearly destroyed a grip.

[Wildfisher]

Be careful with G clamps on cork - I nearly destroyed a grip.

Indeed.  I have made up a rig that protects the handle. A bit of a faff-about but it works. I'll post some photos later. I'll do some final checks tomorrow then we can arrange a time next week.