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How do you calculate (Revisited) staved angles on segmented rings

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Forum topic by Jack Lewis posted 09-22-2017 06:18 PM 1660 views 1 time favorited 7 replies Add to Favorites Watch
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Jack Lewis

188 posts in 860 days


09-22-2017 06:18 PM

Topic tags/keywords: staves segmented spread sheet

I think the method of flat segmented rings has been solved with complete clarity. E.I.. the sleds and “Miter Set” devices. So I don’t want to revisit that.

When I started to calculate the angle between staved segments, the problem of blade angle was added to the miter angle. When a blade angle of 90o (90 degs.) vertical to TS bed is used the stave angle is vertical. I wanted, as an example, a stave that was 45o from vertical. The 90o blade angle didn’t work (naturally) and just guessing 45o blade angle wasn’t the answer either. As long as I was intending to make various segmented vessels of different numbers of staves and different angles, I needed a formula or spreadsheet to calculate the different values and I didn’t want to go through the trial and error with just guessing and trying to fine tune each one.

I think I have the solution but I want someone to confirm or disprove it.

Starting with a vertical stave the blade angle is calculated as (360o/# segments) or in the proven case of 12 segments it is 15o.
If I determine that the stave angle be 0o then the blade angle has to be 90o. This is the same as regular segments.
I then deduced that a 15o difference in blade angle could make a difference of 90o stave angle.
Which became a total of 75o of blade difference or a value of 75/90 or .8333
I then multiplied the value (.8333) to the difference of stave angle from 90o and produced a new blade angle.

Staved Vessel Blade Angle Calculator of jack Lewis

In spreadsheet form A B C D E
1 Stave change Segment angle f/ verticle Blade angle from vert. Segments Per deg. of change from vert.
2 30 90 15.000 12 0.8333333
3 60 40.000

or in SS formulas

2 B2-B3 90 360/d2/2 variable 75/90
3 variable (A2 x E2) + c2

D2 is the number of staves and can be changed
B3 is the angle of the stave from vertical and can be changed

This worked at changes of stave angles 90o, 0o , and 4 and 12 segments so I believe it is fairly accurate at all in between. This blade angle would still require the aforementioned jig to align the stave blank to cut the required segment angle.

If anyone differs or has other ideas PLEASE either reply or PM me. I want this to work and work right. I am tired of wasting material with trials.

-- "Now we are getting no where, thanks to me"


7 replies so far

View Nubsnstubs's profile

Nubsnstubs

1181 posts in 1512 days


#1 posted 09-23-2017 12:37 AM

HUH?? Jerry (in Tucson)

-- Jerry (in Tucson) www.woodturnerstools.com

View Jack Lewis's profile

Jack Lewis

188 posts in 860 days


#2 posted 09-23-2017 01:28 AM

What’s the matter, too deep for you?

-- "Now we are getting no where, thanks to me"

View Loren's profile

Loren

9428 posts in 3430 days


#3 posted 09-23-2017 01:44 AM

This guy appears to have the trig worked out:
http://www.tahoeturner.com/instructions/pdf/handout.pdf

I used to make conga drums when I was
younger. The critical difference was the inside
face was not a show face so the angles I used
were fudged to close the joints on the outside
and fill gaps on the inside. I was familiar with
the trig at the time but never perfected its use
once I got close enough for what I was building.

View Rick_M's profile

Rick_M

10275 posts in 2162 days


#4 posted 09-23-2017 01:59 AM

If I understand what you want to do, M. Wandel made a handy chart for staves.
http://woodgears.ca/miter/
http://woodgears.ca/miter/splayed_miters.pdf

-- http://thewoodknack.blogspot.com/

View roofner's profile

roofner

121 posts in 2065 days


#5 posted 09-23-2017 02:12 AM

Your original formula was wrong but you got the right answer. should be 360 divide by number segments divided by 2 because its the complement of the angle to get 15 degrees. I can not verify what your trying to prove because . I’m not familiar with rest of the problem with the staves.

View Nubsnstubs's profile

Nubsnstubs

1181 posts in 1512 days


#6 posted 09-23-2017 03:55 PM



What s the matter, too deep for you?

- Jack Lewis

Heck yeah, man. I learnt that 2+2 = 4, and 2×2 also = 4. That just about blew my mind. I haven’t been the same since. But when it came to subtracting 2 from 2, and arriving at 0, I was a goner. Don’t even get me started on division….. hehehe…....... Jerry (in Tucson)

-- Jerry (in Tucson) www.woodturnerstools.com

View CharlesNeil's profile

CharlesNeil

2069 posts in 3652 days


#7 posted 09-23-2017 04:45 PM

pretty sure this wont help , but Maybe .. its a really old video but what the heck , making a bucket .

https://www.youtube.com/watch?v=3z4dMBNCSAg

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