The use of Golden number in wood turning

[La Truciolara]

The golden ratio, usually denoted ('phi'), expresses the relationship that the sum of two quantities is to the larger quantity as the larger is to the smaller. The golden ratio is the following algebraic irrational number with its numerical approximation

This number is still quite frequently used by architects, designers, artists to obtain closet o perfect proportions.
A friend of mine, Jacques Portal, Turned this bowl in strict observance of the golden ratio.

For diameters:
370 / 140 = 2.618 (square of 1.618)
From which you can deduct:
370 / (115 + 115) = 1.618
(115 + 115) / 140 = 1.618

For eighth:
75 / 46 = 1.618

We can add than the depth of the bowl is 370 dived by the square of the square of 1.618. But let’s not exaggerate, we can be satisfied to commonly utile 1.618, it’s square or it’s square root. We are not that fussy or anal compulsive. Are we? :lol: :lol: :lol:

 

[Blister]

Looks double dutch to me :shock:

But then I am mentally challenged :?

does anyone else understand it ?

 

[joekid]

well that explains a few things!! why i keep dropping blocks

 

[RobertMP]

http://en.wikipedia.org/wiki/Golden_ratio

Can't say that this looks to be one of the best examples as the height proportions measure to some indefinite point on the curve. Still a nice bowl though.

 

[Anonymous]

Interesting stuff... the usual recommendation for box proportions is 2/5ths for the top and 3/5ths for the bottom:

Applying the golden rule... 2/5 = 0.4

0.4 x 1.618 = 0.65

0.4 + 0.65 = close enough for me :lol:

e.g. for a box with a top of 20mm...
the bottom would be 20 x 1.618 = 32.36mm so a 20mm top with a 30mm bottom would be as near as makes no never mind :wink:

 

[Bodrighy]

Or to put it even simpler.....the rule of thirds. Things always look more proportional, etc if things are done in thirds.

In art and photographic composition things are always seen this way as an ideal.

Don't forget also the rule that there is always an exception to a rule.

So far in my meager turning experience I have found that the most prevalent rule has been that of serendipity.

Pete

 

[duncanh]

I'd have to agree with Robert that this isn't a particularly good example of the rule.
It looks to be a little tall - you say the height is 370 / ((1.618)^2))^2, but I get that to be 54 rather that 75. Is this how the depth of the inside of the bowl (52) was calculated? And why use ((1.618)^2))^2 anyway?

Was the golden number used to determine the shape of the curves?

I've seen several professionals demonstrate and often they have talked about the golden mean before going on to use the 1/3,2/3 rule as an approximation. This is what I'm now guided by - the outside depth of my bowls is usually related in multiples of 1/3 to the diameter, the diameter of any foot is usually approximately 1/3 overall diameter. The widest part of a vessel is usually 2/3 the height.

I've said usually all the time above as I use the rule for guidance rather than something I stick to rigorously. I often mark out in pencil where the rule indicates and then judge if that would give a pleasing shape. Sometimes though I just put the would on the lathe and see what shapes the wood (and my mind) come up with.

If I apply this rule to the bowl you posted then I would get...

overall diameter = 270
overall height = 270 * 1/6 = 62
foot diameter= 123
height to centre of ogee= 21
inside depth not measured but follows the shape of the outside

Obviously this is all down to personal preference in the shape produced - I've just done a quick sketch based on my dimensions above and I preferred it, but then I would since that's the way I've been producing my turnings for a while now.

I prefer the 1/3,2/3 rule as it's also much easier to work out in your head

Duncan

 

[Anonymous]

serendipity

Don't need a calculator for that one Pete :lol:

Have to say that I've never used any prior calculation when turning bowls; for that matter I rarely have a shape or design in my head at the start... could it be that the shape is already in the wood and all I'm doing is removing the waste?

rule of thirds... one third bowl, two thirds waste :lol:

 

[Bodrighy]

serendipity

Don't need a calculator for that one Pete :lol:

Have to say that I've never used any prior calculation when turning bowls; for that matter I rarely have a shape or design in my head at the start... could it be that the shape is already in the wood and all I'm doing is removing the waste?

rule of thirds... one third bowl, two thirds waste :lol:

As Michael Angelo put it, "My job is to remove from a piece of stone all the bits that don't belong on the statue."

He probably said it in Italian and made it sound much better.

When I hear that a pro Like you (Graham) have the same technique as me e.g. start wit a block of wood and see what happens. I feel that maybe there is hope for me yet.

 

[Anonymous]

I have to confess it's a bit Jekyl and Hyde in reality...

I sometimes have to turn to customer's specs but I also enjoy the freedom of pleasure turning where I can do what I want...

Whether you're a golden numbers person or whether you're a poke it and see what comes out type or somewhere in between, it doesn't matter...
enjoying what you're doing does...

 

[duncanh]

One of the best pieces of advice I've heard/seen from several sources is not to let the wood dictate the final shape/dimensions of your finished turning. Just because a bowl blank is xcm high doesn't mean that the finished bowl should be the same or as close to it as possible.

Early on in my turning I never really planned anything and I tried to get as much out of the wood as I could - all my bowls tended to have quite deep walls and curve in at the last minute (kind of like a salad bowl) and so looked bottom heavy.

I think the reason for this was lack of confidence in my turning and lack of experience in what looks good (to my eye at least). Once I'd got what I thought was a reasonable shape I stopped turning for fear of making a mess of it and wasting the wood - we all know that you can take it off, but if it goes wrong you can't put it back! Now-a-days I have more confidence and can (usually) get the shapes that I want.

But as I've said before, it's all personal preference and a pleasing shape is subjective.

Duncan

 

[Anonymous]

One of the problems with rising skill levels is that it tends to rule out the innovative shapes arising from the odd catch or two :lol:

On the other hand it does mean that you can achieve any desired shape... and keep it...

 

[Bodrighy]

As a newbie at turning I find that what I end up with is never what I started out thinking of. OK so I start thinking 'Bowl' but that's as far as it gets. With the inevitable catches (for me) and the occasional, 'what if I do this' I usually end up with something that makes me thinbk, "Wow, if I can do this now, what can I do when I know what I am doing. I enjoy watching the wood take shape, seeing and feeling something being created almost despite my lack of skill and still ending up with something that, at worst, is not bad. I am sure that, put alongside Chas's or Graham's, my stuff would look like a before and after show but each time I 'create' something I learn something new even if it's a case of not to try that again.

WOW dis I say all that!!

Pete

 

[PowerTool]

each time I 'create' something I learn something new even if it's a case of not to try that again.

Pete

Same here - I start off with a general plan of what I intend to make,but sometimes the wood has other ideas :lol:
e.g. finding a crack or shake halfway through turning something,or trying to put some detail grooves on a bowl and finding the timber only likes being flat
That's why I'm still trying out different timbers - to learn about them! (Good and bad bits)

Andrew

 

[duncanh]

It would be an interesting exercise to take some of the turnings that you've done by eye where you think that you've got the shape just right, take measurements and see if they are anything like the golden mean or 1/2,2/3 guidelines.

Or maybe we should just forget about how we go about designing and just get back to turning!
Unfortunately I've been unwell for months now and haven't felt up to using the lathe much:-(

Duncan

 

[joekid]

im working on the photographic rule of thumb ,if it looks ok it generally is, how proffessional do you want to be, ok theres some of you guys will be able to work to meticulous limits, but i start off with a mental plan and end up with something totally different,break the rules and throw composition to the wind

 

[Anonymous]

I like that bowl a lot

I use the golden ratio in furniture as do many others - since before the ancient Egyptians.

I find most pieces that use it look very pleasing to the eye, as does the whole of nature which is where it was first observed

 

[La Truciolara]

I'd have to agree with Robert that this isn't a particularly good example of the rule.
It looks to be a little tall - you say the height is 370 / ((1.618)^2))^2, but I get that to be 54 rather that 75. Is this how the depth of the inside of the bowl (52) was calculated? And why use ((1.618)^2))^2 anyway?
Duncan

I guess it's difficult to measure from the picture. The measures were taken form the bowl itself.

In any case, at least this message created quite some comments. I thought it might have been of interest to you to see that the golden rule can be applied to turning. It was by no mean a suggestion that this should be used.
But I must say that with this rule or the 1/3 rule it is quite difficult to turn a piece as ugly as some I have seen.
In general, trust your taste... you'll like the piece you have turned :wink: :lol: