What is the best/easiest way to figure out "taper-offset" for butt wraps? Stan



Edited 1 time(s). Last edit at 02/01/2006 12:52AM by Stan Gregory.

Visualwrap

That's probably the very best way at this point. But there are many others - older pre-VisualWrap types.

I used to do a lot of closed wraps and would just figure a ratio of circumference to length between centers. Just seemed the simplest way to do it for me.

You can also figure out how many centers will fit in your planned wrap length and then on a piece of notebook paper plot the circumference on a line drawn vertically on the left. Put the circumference of the butt on the first line and the circumference of the tip-most center on the last line of however many centers you have. Connect the dots, so to speak and now you have a slanted line running to the right of your vertical line. Measure the distances between the two lines for each center and transfer them to the blank. What this does is compact the distance between centers near the butt and elongate them slightly towards the tip. You won't notice the slight difference in center lengths on the wrap but will provide the extra space you need to squeeze in those last few threads.

Stop by the RodMaker booth in Charlotte and I'll walk you through it. It's much easier to show you than to try and explain it in writing.

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Stan,

The Dale Clemens books cover that also.

Raymond Adams
Eventually, all things merge, and a river runs through it..

Stan, I apologize for being so brief. You asked for easiest, with VW you take the starting & ending diameters & enter them, and it gives you the spacing based on the length.

Visual Wrap is an awesome tool!!

Raymond Adams
Eventually, all things merge, and a river runs through it..

Second Best Method: Using the Clemen's "Taper Offset Layout" (TOL) Method for Center Spacing is recommended. It can be found in Clemens' CTRA (Custom Rod Thread Art), pages 21-23.

Let's call "DELTA" the spacing between centers for a 90 degree square diamond.

Sparing a discussion of the geometry involved, (You're welcome!), the proper spacing for square diamonds equals exactly one circumference length, using the rod blank's diameter at that particular location.

Remember that it is a tapered rod, That taper percentage is typically between 0.5% to 2.00%. This is based on an expression:
Percent Taper = 100 * [ [ OD(1) - OD(2)] / LENGTH ] ,
where: L = the distance along the rod blank between OD(1) and OD(2)

At the butt end of the wrap, let's say that:
DELTA(1) = PI * OD(1) = 32 mm
At the rod tip end of the wrap, let's say that:
DELTA(2) = PI * OD(2) = 28 mm

And let's say that the LENGTH of the butt wrap is intended to be ~160 mm. This is a GUESTIMATION at this point, because you simply CANNOT DICTATE the (LENGTH of the Butt Wrap) or the (DISTANCE -DELTA- between centers) IF you insist on having all PERFECTLY SQUARE Diamonds. *** IT IS MATHEMATICALLY IMPOSSIBLE *** to INDEPENDENTLY select the spacing values once you demand a SQUARE DIAMOND. (Just take my word for it, unless you have a degree in mathematics. Then maybe you can enlighten us as to why.) IF you are content with NON-square diamonds, then you get to dictate the values for DELTA.

Which brings us back to Clemens' Taper-Offset Layout (TOL) Method:

At the butt end of the wrap, let's say that:
DELTA(1) = PI * OD(1) = 32 mm
At the rod tip end of the wrap, let's say that:
DELTA(2) = PI * OD(2) = 28 mm

The TOL Method "Swaps" the DELTAs, FORE and AFT, and .
Uses an AVERAGE VALUE at the mid-point of the Length
DELTA(Mid) = 1/2 * [ OD(1) + OD(2)]
DELTA(Mid) = 1/2 * [ 32 + 28 mm] = 1/2 * 60 = 30 mm

For practical reasons, you cannot expect to adjust the center dots to any position more accurately than to the nearest 0.50mm or 1.00mm. So the additional calculations to accurately determine DELTA become an exercise in mental gymnastics and geometry that is interesting, but impractical.

So, now you just want to change the Spacing value DELTA by 0.5mm or 1.0mm for each center, as you move away from the mid-point (or either end-point for that matter).

Now the series of Diamond Centers has Spacing values:
28, 29, 30, 31, 32 mm.
This should give you n+1 diamonds (6) for a standard 2-axis pattern.

This TOL Method will give you a cross-wrap layout with the most symmetrical blend of angular distortion (diamond compression or elongation) and the most symmetrical distortion of the spacing interval (DELTA).

This is one of those things in life where it is absolutely impossible to independently select the value of more than ONE VARIABLE in this geometrical-mathematical system. Once the rod blank taper is fixed, and you select one other variable (such as the intersection angle at the cross-threads, or the interval between intersection centers) than any other variables are automatically determined, dependent on the rod taper and on the other variable that you independently selected already.

In the TOL Method, you select ROD TAPER and the INTERVAL Delta. You are no longer free to dictate the shape, or the free-open distance between outer thread bands when trying to do a CLOSED WRAP. The taper and interval geometry will do that for you, whether we like it or not. But that is the trade-off you make for receiving a wonderful simplification of the math involved. It is not a severe distortion of shape or filling distance, mind you. It is just to be kept in mind as you see the shape shift or the threads need cramming on a closed wrap. It is all just one of the fascinating, IMO, effects of taper on a cylindrical body. ...

I have discussed this with THE MAN, DAVID BOYLE, "Mr. VisualWRAP" himself, on the RBO Forum [www.rodbuilding.org], and via e-mail in recent weeks, and to make a long story short, this is indeed the case. YOU CAN'T HAVE IT ALL, ... So, don't lose any sleep over it trying.

Just use the TOL Method, wrap on, wrap away and be done with it. Or better yet, consider investing in VisualWRAP, because Clemens' book CRTA is OUT-OF-PRINT. ... LOL, -Cliff Hall+++, Gainesville, FL-USA*****

Also see [www.rodbuilding.org] for discussion of spacing intervals in multi-axis systems.



Edited 1 time(s). Last edit at 02/01/2006 02:38PM by Cliff Hall.

And I should mention that Mark Crouse will be covering this in his introduction to cross-wrapping at his seminar presentation in Charlotte in 3 weeks.

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Tom (or Billy),
Are there any plans or talk about doing a Visual Wrap demo at a future show? I have the program but am a little hesitant to use it due to the learning curve. A couple of tips and maybe a hands-on demo would greatly help. Thanks, Randy.

We did it (seminar) last year and will probably bring it back next year. David Boyle plans to return for the 2007 event.

Billy can probably help you with it at this year's event. He'll be in the NERBS booth.

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the NERBs will have a lap top set up in Charlotte where you can ask Q's about VW. You can also contact me directly via e-mail and I'll try to help. Another reference is this link: [www.tightwraps.com]

Check the MISCELLANEOUS VIZWRAP DOWNLOADS, Script Tutorial & Standard help file.

I agree, VisualWrap is a breeze to get your tapered spacings. I have never tried the other methods, so I can not comment on them, but I have had no issues with the VisulaWrap.

Oh, oh, … In case I did another TMI (Too Much Information) on my Reply above, … Let me fillet that sheepshead and extract the clean meat. –LOL, -Cliff Hall+++

Clemens’ Taper-Offset Layout (“TOL”) Method. CRTA, p.21-23.
Butt-End Interval = PI * OD = 3.14 x 17 mm = 53 mm
Tip-End Interval = PI * OD = 3.14 x 15 mm = 47 mm
Swap Intervals, from Butt to Tip End: Now
Intervals (Butt --> Tip): 47.0, 48.5, 50.0, 51.5, 53.0 mm.
Length = minimum 250.0 mm, for the distance between 6 centers.
The TOL Method minimizes the distortion of the shape of the diamond & the amount of packing required to close a wrap in a symmetrical fashion. Using convenient values for the intervals is more practical than exact calculated values.

Kirkman’s Graphical Method can be expressed in a formula as
Interval = Interval * [ 1 – (%Taper / 100) ] . Where:
%Taper = Percent Taper = 100 * [ [OD(Butt) - OD(Tip)] / LENGTH ].
Example: For a 2.00% Taper, from 100 * [(23-20)mm / 150mm] = 0.020
Interval = Interval * (1 – 0.020) = 72 * (1 – 0.020) = 72 * 0.98 .
Intervals = 72, 70, 68, 66, mm etc. or
Intervals = 72.0, 70.5, 69.0, 67.5, mm etc.



Edited 1 time(s). Last edit at 02/02/2006 01:31AM by Cliff Hall.

Thanks, guys for all the replys. I think I'll give VisualWrap a try.