Help needed cutting segments for bowls

[ps.harris80]

Hi all

Hope this is in the correct section.

I hope someone can help with this as maths is not my strong point.

When cutting segments to glue together to make a bowl, I know the angle part is easy that is 360° divided by the number of segments, divided by 2 gives the angle for each end of the segment but how do you work out how long each segment is, is it as simple a calculate the circumference and divide that by the number of segments or is there a more accurate way of doing it.

Thanks for any help with this.

Paul

 

[Myfordman]

Take the tangent of the angle you calculate for the end of each segment multiply by the diameter you want to give the length. However add a bit more to allow for turning the outside..
Say 18 sides gives 10 degrees on both ends of each side and you want a 200mm circle, each segment is 200* tan 10 = 200*0.176=35.26mm round up to 36 or 37mm for a turning allowance.

if you have a smart phone then select calculator, rotate to landscape, enter the angle, press tan and multiply by the diameter. Done

 

[Sachakins]

Download Segment Calculator 2 app, does it all easily for you.

https://play.google.com/store/apps/details?id=com.byroid.segmentcalculator2

 

[sneggysteve]

I use this - dead simple

https://www.blocklayer.com/woodturning-segments

 

[Stigmorgan]

Download Segment Calculator 2 app, does it all easily for you.

https://play.google.com/store/apps/details?id=com.byroid.segmentcalculator2

Just tried to look at this and it came back as not available for my device I've got a brand new Samsung S23 Ultra

 

[Sachakins]

Just tried to look at this and it came back as not available for my device I've got a brand new Samsung S23 Ultra

?, I've got it on my S21 FE Samsung, and works fine. It's Android 13, One UI 5.1 and Android security patch 1st September 2023.

What version android you on?

I've just deleted it and tried reinstall, to check the link, it all worked fine and runs OK, so surprised it not compatible with S23?

Also got it installed in galaxy tab S5E, but that's only Android 11 and that's fine too.

 

[Jester129]

Sorry to interrupt the thread - Stimorgan, can I ask where you got your phone from? It appears Banggood cannot supply any smart phones to the UK, which I was not aware of.

 

[ps.harris80]

The segment calculator app just reports that it is not available for my device as it was made for an older version of Android

 

[ps.harris80]

Just found an app called simple segment calculator which seem to function.

The one linked above is only available for devices running an old version of Android, unfortunately it doesn't say how old it needs to be.

 

[Sachakins]

What android version is your S23 on?

 

[Yojevol]

There's a problem here because a segment is being refered to. It should be SECTOR.
Here is a sector calculator wwhich is what I believe @ps.harris80 is looking for

 

[Sachakins]

There's a problem here because a segment is being refered to. It should be SECTOR.
Here is a sector calculator wwhich is what I believe @ps.harris80 is looking for

I think not, the sector gives a chord length, not the max segment length, which you need for the segment being cut, the chord length would be shorter than the external segment length required to contain the diameter of the outer ring dimension that's required.

 

[Steliz]

You don't have to use software unless your going for a very specific finished result.
Once you have a jig built to cut your segments at the correct angle then the only dimension left to decide is the segment width which determines the overall diameter of each ring. I generally stick to 12 segments per ring and 22mm width = 80mm diameter and 41=150 (roughly). The height of the rings can be varied for added effect. Decide on your desired finished shape and create the rings accordingly. You can either start with a rough idea and see how it turns out or you can start with a specific goal in mind and go from there.

I answered a similar question recently.

 

[Yojevol]

I think not, the sector gives a chord length, not the max segment length, which you need for the segment being cut, the chord length would be shorter than the external segment length required to contain the diameter of the outer ring dimension that's required.

Yes I agree with you there. I raised the point because we use the word 'segment' (as in segment of an orange) incorrectly. The geometric definition of a segment is the outer portion of a sector, ie, the bit between the chord and the arc. Being pedantic I know but if you're searching for an answer on-line it helps to know the difference.
BrIan