Moderators: Random Orbital Bob, nev, Noel, Charley, CHJ

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By Blocklayer
#1199597
I've just put up a new Segmented Turning calculator on blocklayer.com some of you may find helpful.
https://www.blocklayer.com/woodturning-segmentseng.aspx

It just works out the geometry for the segments, with visual animated diagrams so you can see what you end up with.
I'm not a wood turner, so any ideas, or if it needs editing, additions or fixing please let me know.
Attachments
Seg.jpg
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By CHJ
#1199631
Always good to have alternate versions of such aids, we all have our preferred methods more chance of finding a guide that suits what we need to do.

J-G wrote:Excellent in most respects - :)

It took me a while to find out how to use metric units #-o

A minimum thickness of 20mm is far too high (for me) I often get down as low as 2mm


If you are happy to work in decimals rather than fractions then This version doesn't care what the units are. My limitations are always centred about cuting the segments and assembling accurately enough and invariably leave myself more padding on thickness than absolutely necessary.
seg.jpg
By J-G
#1199719
You're right CHJ - I've had a shortcut to your version on my desktop for quite some time (I've even used it on occasion :D )

I only commented on blocklayer's because of the 20mm limitation which I found odd and he did ask for opinions.
Last edited by J-G on 11 Jan 2018, 17:41, edited 1 time in total.
By Inspector
#1199739
The upside to Blocklayer's calculator is the little diagram at the bottom giving the angles.

Not being a segmented I wonder if the number of segments is enough. 20 seems a bit low. Is it?
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By CHJ
#1199748
Inspector wrote:......Not being a segmented I wonder if the number of segments is enough. 20 seems a bit low. Is it?
Depends upon how busy you want the piece to look or how intricate you want the design. The bulk of my simple stuff only uses 12 angled segments, albeit most with 24 pieces of wood in any one ring.


As soon as you start increasing the number of segments the accuracy and control of the angles becomes progressively more difficult when doing solid work, open segment work is not so critical as you don't have mating angular faces.

There's a reason I stick to producing simple stuff with my basic kit
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By J-G
#1199769
CHJ wrote:The bulk of my simple stuff only uses 12 angled segments, albeit most with 24 pieces of wood in any one ring.

There's a reason I stick to producing simple stuff with my basic kit.

Those statements seem to be at odds CHJ :? I would hardly refer to your segmented work as 'Simple' and using '12 angled segments... with 24 pieces of wood' emphasizes that point.

I'm now assuming that you use parallel sided 'thin' segments - rather than also tapering them - in which case your calculator won't give you correct figures for the length of the main segment at the specified outside diameter.

Neither calculator gives the option to have anything other than regular (equal) segments and I appreciate that that would complicate the maths substantially of course, though allowing for parallel 'thin' segments wouldn't be too difficult.
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By CHJ
#1199792
J-G wrote:....

.....in which case your calculator won't give you correct figures for the length of the main segment at the specified outside diameter.
.


Why not, the calculated segment length is the same regardless of the number of pieces of wood assembled to make the segment.

This WIP should explain as far as the assembly is concerned it's still only 12 segments cut at 15 deg.
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By CHJ
#1199812
graduate_owner wrote:This is something I would like to try.

K


Off-cuts and spare plank ends of wood can be somewhat cheaper than turning blanks for a given volume of a piece.

You do have to factor in more time input to the preparation and cost of adhesives,

It's no way to rapidly reduce the hoard of surplus wood stock though judging by my last two years performance.
By J-G
#1199917
CHJ wrote:Why not, the calculated segment length is the same regardless of the number of pieces of wood assembled to make the segment.
... as far as the assembly is concerned it's still only 12 segments cut at 15 deg.


I'd assumed that the thin segment would be in addition to the main segment rather than included. The WIP does explain your method fully.

For the few segmented items I've made I've tapered the thin sections as well - much more complex of course - and not necessary.
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By Blocklayer
#1200481
Thanks all.
I've added a bit to the calculator - dropped it down to 1/64" rounding, and added the option to display the segment dimensions as decimal inches.
It now also has inner and outer 'margin' settings, to allow for curved or angled sides.
Will look at adding calculations to find correct margins for required side angles next.

J-G There's Metric and Imperial versions of the calculator. The smaller Imperial tab is directly below the Metric tab in the menu at top.
And are you sure you need 2 mm thickness (~ 5/64 ") ?? That's pretty thin. I have a fair idea what would happen if I tried that!

Any suggestions to improve (or fix) the calculator appreciated.
By Roger C
#1200565
Thanks I do not see the tab for metric. I do understand imperial as I build miniatures 1/12 scale but rest of my wood work is metric Thanks
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By CHJ
#1200572
A couple of observations.

PDF print option not working in Edge Browser on my machine.
seg.jpg
seg.jpg (10.6 KiB) Viewed 355 times


Segment Graphic unreadable in smaller sizes, too cluttered with text, can't check printed version because of above problem.
seg1.jpg
seg1.jpg (11.39 KiB) Viewed 355 times


Angles quoted are internals, needing changing to reciprocal on most machines as Angles are referenced assuming cutting blade is at 90 deg for chop saw fence or 0 deg for table saw.
For instance for 12 segments most scales need setting to 15 deg. not 75 deg.
seg2.jpg
seg2.jpg (8.67 KiB) Viewed 355 times


seg3.jpg
seg4.jpg