Wanted to give an optical chevron a go on a split grip. Is this type of wrap still considered "open", thus I can use equal spacing taken from the mid-diameter x pi, or do I need to space it according to the taper? Will probably wrap a white underwrap, how do you mark the centers, use marked ncp thread? Many thanks!

Mike,
Yes that is considered an open wrap. You can use equal spacing but the spaces will vary slightly with the taper. Since it's a farily small area between the grips I don't think it will affect much. There are a bunch of ways to mark the centers. On a split lke that, I usually lay out a piece of masking tape and mark it. I then lay the masking tape on the blank with the edge along the axis and mark off the reference points. Also, if you want your white underneath to stay nice and bright on a darker blank you can paint the blank white first then just do your wrap over that. Granted the white underneath is only visible between the pattern, it just depends on how particular you want to get. Just how I do it, Randy.

Thanks Randy, I appreciate your help. I wasn't sure if everything would stay "centered up" since I'm filling a space of about 6.5". This is a dark blank, so I may try to paint the area instead of wrapping with white thread+CP to stay bright. Only one way to find out... Thanks again, Mike.

NCP White thread over acrylic paint;
Or two layers of NCP White thread
for the whitest white underwrap.


For some further references on the TOS / TOL:
Billy Vivona & others comment:

Taper Offset - Best Method
Stan Gregory ... Feb. 1, 2006 ... [www.rodbuilding.org]
"What is the best / easiest way to figure out "taper-offset" for butt wraps?"

Closed wrap and CP issues
Phil Richmond ... June 15, 2006 ... [www.rodbuilding.org]

For CLOSED WRAPS, where the issues of thread cramming & shape distortion are of more consequence, this excerpt may help simplify things:

Re: Taper Offset - Best Method
Cliff Hall 02-01-06 11:03
[www.rodbuilding.org]
Second Best Method: Using the Clemens’ "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. ...

... 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 0.50 mm or 1.00 mm. 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. ...

... ETC, etc, etc, ... -Cliff Hall, FL-USA

Thanks Cliff, I really appreciate your work, plus the helpful links. (I'm going to graduate from diamond and chevron U one of these days!) I think that I will go with the paint route, as a bright undercoat is what I'm after, plus I believe it may be easier to mark the centers. Off to grap the calipers, many thanks again for your help! Mike

Mike Canavan - You're welcome. Got too tired to finish Replying last nite. You seem to have figured out the rest of the story. …

When doing a criss-cross pattern butt wrap within a confined space, such as between the grips in a split grip, you have to select a number of criss-crosses (centers) and end-wrap tie-down band-width that are compatible with the center angles and number of intervals you want to produce. The easiest thing to do is to measure the ROD BLANK DIAMETER, (at the two ends and at the mid-point), and let the mid-point diameter DICTATE the number of Centers (diamonds) in the overall pattern.

You probably do not need to have perfect 90-degree angles. Multiply your aft, mid-point, and forward OD's by 3.14 (Pi). Let's say you get 42, 40, and 38 millimeters, respectively. Using the mid-point OD, that is roughly 40 mm (1.6") per criss-cross. Divide your free space between the grips by this interval, and that will give you the maximum number of fairly square diamonds you can fit in between the grips. You can elongate the square or compress it to suite your situation. … Doing a NEAT wrap that is SYMMETRICALLY laid out in between the grips is usually more important than having a perfect 90-degree crossing. … -Cliff Hall.
[www.rodbuilding.org]

Thanks again Cliff, appreciate the extra help! I've been practicing new wraps on doweling, and taking mental notes while doing so on centers, spacing, etc. Think I've got this nailed down, seems much easier than mentally expected. Ready to tackle the taper now! Thanks again. Mike