Hi folks, I want to try a 6-axis 3D chevron but I'm not sure how to offset the marks on each axis. I'm not sure even after reviewing books by Clemens, Kirkman, and Vivona.
Let's assume my centers spacing is 12mm (just picked a random number to keep math simple)

For a 4-axis, 90 and 270 axis marks are started at the beginning of the wrap while 0 and 180 axis marks are started 6mm from the start of the wrap.

For a 6 axis, is it something like
0 and 180 axis 0 offset
60 and 240 axis 4 offset
120 and 300 axis 8 offset

Thanks for the help
John

John Shear
Chippewa Falls, WI

John,

For 4, 6, or 8 axis wraps, you must lay out 2, 3, or 4 complete sets of crosses (if you want to mark every cross - more experienced wrappers may not need to do this).

First things first. This is a closed wrap, so taper offset calculation is in order. For your 6 axis wrap you will calculate the crosses for a standard 0-180 and also at the tapered 1/3 and 2/3 points between the main crosses (for the entire length of your wrap, not just the first cross layout). Using your numbers for the 12mm layout and taking into account taper you might have:
0 axis at 0"
60/300 axis at 4.1(taper offset 4.1)
120/240 axis at 8.1(taper offset 4)
180 axis at 12 (taper offset 3.9)
offsets 4.1 + 4 + 3.9 = 12.

Okay if you're with me up to this point, it gets a lot easier now. To help us with referencing which opposing axis are pairs as we are turning the blank I would use a color coding system, let's use red, white, and blue. wrap a band of tape on the blank and mark opposing axis on the tape with color reference marks. 0 and 180 will get red, 60 and 240 will get white, and 120 and 300 will get blue. Since in this wrap all axis will be wrapped at the same time, it will be easy to remember wrap up and down on red, then up and down on white, up and down on blue, and repeat until done.

Next step, layout 6 axis lines in the area of your wrap, one on each axis (0, 60, 120, 180, 240, and 300). Now, you will mark every distance in your taper offset layout by drawing a circle around the blank at each distance. For accuracy purposes, make sure to use baseline distances from a common point, don't do incremental distances from point to point. If you make a mistake on any single incremental layout it will carry over into all the remaining layout points. Baseline layout errors will only show at that one error and will easily stand out as a mistake allowing you to correct it before proceeding with the wrap. The easiest way to circumscribe the circles is to mount the blank in your wrapper and with the rod rotating bring your marker into the rod as it's turning to draw the circle. This is the same procedure as a woodturner would follow when they layout the transition points from profile to profile in a turning.

What you should have now is six longitudinal layout lines on axis 60 degrees apart, and a circumscribed circle at each axis cross and the 1/3 and 2/3 points between each axis cross. Every point where a circumscribed line crosses an axis line is a point where your threads will cross. Use your color codes to keep track of the order and sequence as you wrap so you don't accidentally drop or add an extra thread. if you think of your blank laid out flat, the crossing lines will look like graph paper lines and your threads will be laid diagonally from corner to corner.

Hope this helps.

John P,
I chose the 3D chevron because I understand it's an open wrap so I wouldn't have to worry about taper offset stuff.
I do understand your explanation though and like the tip of using different color tape to keep track of my axis'.
I do intend to mark all 6 axis' on the underwrap since I am not proficient enough to make it look really nice without all the reference marks.

John

John Shear
Chippewa Falls, WI

John,

Sorry, I wrote something misleading and didn't catch it until your reply. I should have been more clear with the comment about a closed wrap, that is the wrong terminology; your correct that it's an open wrap. I was thinking in terms of underwrap plus the chevrons covering the blank and the taper offsetting will give you equal sized openings where the contrasting underwrap will show.

So really what I should have wrote was think of this open wrap like a closed wrap for the purposes of spacing.

If you don't do a taper offset, your background underwrap will look large near the butt and small near the tip which doesn't work well when you're trying to get the 3D effect.

Ah, I get it John. I'm going to do at least one practice wrap before I do it on the good rod, so I'll not do the TOS for the first test and see what it looks like. If I'm not happy I'll do a second test with TOS. I have lots of time to kill in winter.

John

John Shear
Chippewa Falls, WI

Post a pic when you get it done.

Well, I started with these offsets as I mentioned above:

0 and 180 axis 0 offset
60 and 240 axis 4 offset
120 and 300 axis 8 offset

and it looked really lopsided so I cut it all off. I think next I'll try offsets like this (assuming 12mm centers) to get more square boxes:
0, 120, 240 axis 0 offset
60, 180, 300 axis' 6 offset

I think I need to look at more pictures.

John S.

John Shear
Chippewa Falls, WI

Well, I started with these offsets as I mentioned above:

0 and 180 axis 0 offset
60 and 240 axis 4 offset
120 and 300 axis 8 offset

and it looked really lopsided so I cut it all off. I think next I'll try offsets like this (assuming 12mm centers) to get more square boxes:
0, 120, 240 axis 0 offset
60, 180, 300 axis' 6 offset

I think I need to look at more pictures.

John S.

John Shear
Chippewa Falls, WI

John,

If you would like some help determining the crosses using a tapered offset layout, shoot me an e-mail and I'll get you set up. If you click on my name at the top of my posts my e-mail is shown there.