# Any magic ratios on hollow forms?



## Treecycle Hardwoods (Aug 14, 2014)

I am looking to turn more hollow forms. Currently my max depth is about 7-9" and a 12" diameter. Previous to this I was only able to do small stuff 3-5" tall and 2-4" in diameter I really was just learning on the smaller stuff and didn't pay much attention to the best form possible. I am looking to improve in this area as I start doing larger HF. 
My questions are:

Is there a good ratio of height to diameter in hollow forms? 

Is there a good ratio of opening size to diameter in hollow forms?

Thanks in advance for any help guys!


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## ironman123 (Aug 14, 2014)

Are you farmiliar with the rule of the "Golden Mean"? Used in length to width proportions some times. google it or bing it.

Reactions: Thank You! 1 | Agree 1


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## DKMD (Aug 14, 2014)

No magic formulas that I'm aware of, but the golden ratio/rule of 1/3's is always a good starting place for proportions. Shoulder height 1/3 down from the top or up from the bottom seems to look good usually. Opening size is a matter of taste, but I like a little upturn or detail near the opening to frame it. I like a good tuck at the bottom to give lift, but others like a more abrupt base or even a foot. I think a continuous curve(no flats) is probably more important than anything else.

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## ironman123 (Aug 14, 2014)

The golden ratio is phi (1:618), not rule of 1/3's as stated above. Maybe that is a shortened version used by some.

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## Treecycle Hardwoods (Aug 14, 2014)

Thanks for the help gents. I got a HF blank all prepped for this weekend. Gonna give er a whirl. It measures 9x9x12. Nice willow burl with some eyes, curly figure, and dome nice color contrast. I was mostly concerned about the entry hole I have no bit extenders so I need to use a bit big enough for my chuck to fit in so I can get the hole deep enough. I think I will go with a 2.5" or slightly bigger.


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## TimR (Aug 15, 2014)

I'd concentrate on keeping smooth curves, thinking about the kinds of transitions in a french curve maybe. Hardest thing for me when doing longer more slender forms is avoiding flat areas. Use a straightedge with a light behind it to help spot flat spots that really throw a form off. Squattier forms seem more prone to the shoulder dropping a bit and becoming more sphere-like, but that's not always a bad thing.
Good practice is to try and draw out ahead of time what shape you're after, full scale, and then push yourself to duplicate it on the lathe. Especially good if you're doing something 'different' and need a reminder of what you're after. I still do this time to time if the proportions of the blank don't immediately jump at me the shape of the form I'm after. 
Most of us have this tendency to try and use the most out of any block of wood. Be willing to shave off the block to get the best figure or perhaps feature, (knot/void/burl/etc) to show in the end.

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## barry richardson (Aug 15, 2014)

Treecycle Hardwoods said:


> Thanks for the help gents. I got a HF blank all prepped for this weekend. Gonna give er a whirl. It measures 9x9x12. Nice willow burl with some eyes, curly figure, and dome nice color contrast. I was mostly concerned about the entry hole I have no bit extenders so I need to use a bit big enough for my chuck to fit in so I can get the hole deep enough. I think I will go with a 2.5" or slightly bigger.
> View attachment 57560


That sounds like a good plan Greg. I usually go with a 2 1/2 for that same reason, I even have a 3 3/4 I use some times if I really want to hog it out, but it's hard on the tailstock. You will appreciate that larger hole when you start hollowing. I've made a couple with pretty small oppenings, but it's not worth it to me, lots more work for a less pratical vessel.

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## steve bellinger (Aug 15, 2014)

Greg I think you should do what most folks do when starting HF's. Go and steal a pic off the web some where of a form that you really like.Tape it on the wall in front of you as you are turning. Then try coping it the best you can.

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## duncsuss (Aug 15, 2014)

steve bellinger said:


> Greg I think you should do what most folks do when starting HF's. Go and steal a pic off the web some where of a form that you really like.Tape it on the wall in front of you as you are turning. Then try coping it the best you can.



Greg -- not that it belongs in this thread (as it directly relates to the question you asked at the beginning) but Steve's suggestion is excellent.

One further tip -- I found it helps to have the picture rotated 90 degrees so it matches the orientation of the workpiece while you're turning it. Saves cranking your neck each time you look from the picture to the lathe

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## Treecycle Hardwoods (Aug 17, 2014)

Whew the weekend flew by! I did this Friday night but am just finding time to post it here. HF measures 6 in diameter and 7 ish tall. I was hoping for something a little bigger in diameter but there was a deep bark inclusion in the burl and likely would have been a problem. The piece started 12" long, I was hoping for this shape in a bigger size but the proportions were off at the 6" diameter so I made it shorter. The entry hole is 2 5/8. I chose the hole size before I started turning because I have a new tool and wanted to see in there a little better the first go around.

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## ironman123 (Aug 17, 2014)

Good shape Greg.

Reactions: Thank You! 1


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## TimR (Aug 18, 2014)

Treecycle Hardwoods said:


> I was hoping for something a little bigger in diameter but there was a deep bark inclusion in the burl and likely would have been a problem. ... I chose the hole size before I started turning because I have a new tool and wanted to see in there a little better the first go around.


The form makes me think of upside down versions of a form Curt Fuller does with a lid for a canister. The decision to go big on opening while getting use to new tool is smart. I have destroyed many openings before I had good understanding of how a tool would react to minor changes in approach. 
As for the bark inclusions...shoot, I choose to keep them for added interest, but each turning has it's own priorities depending on what you're after. 
Any surprises along the way while turning this piece?

Reactions: Agree 1


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## Treecycle Hardwoods (Aug 18, 2014)

TimR said:


> The form makes me think of upside down versions of a form Curt Fuller does with a lid for a canister. The decision to go big on opening while getting use to new tool is smart. I have destroyed many openings before I had good understanding of how a tool would react to minor changes in approach.
> As for the bark inclusions...shoot, I choose to keep them for added interest, but each turning has it's own priorities depending on what you're after.
> Any surprises along the way while turning this piece?


Only surprise was how deep and large the inclusion was. It ran the whole length of the piece. There are 3 small ones still in there, but if i had left the big one it would have split for sure. Other than that it was pretty straight forward. I will need to play with the hollowing tool a little more. It cuts pretty aggressively as I have it set up.


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## Treecycle Hardwoods (Oct 15, 2014)

Update. .... I hollowed this bugger out 2 months ago. It stopped loosing weight this week so I decided to finish it off. It cracked a little so I filled them with lapis. I put a coat of tung oil on it just before the pix and it was all soaked in before I was done. I think I am gonna make a collar and finial for it but I'm not sure what species it will be.

Reactions: Like 5 | Way Cool 1


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## elnino (Nov 2, 2014)

love the lapis! looks good! what hollowing tools did you use?

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## Treecycle Hardwoods (Nov 3, 2014)

elnino said:


> love the lapis! looks good! what hollowing tools did you use?


I used a sorby hollowing tool for the most part. The tool comes with a scraper insert but I replaced that with a hunter style carbide insert I got off ebay.


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## ironman123 (Nov 3, 2014)

Looking good Greg. Waiting to see it in it's final stage with finial.

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## Treecycle Hardwoods (Nov 3, 2014)

I forgot to post pix it has been done a few weeks now. The collar and finial are apple.

Reactions: Like 2 | EyeCandy! 1


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## ironman123 (Nov 3, 2014)

That is some real nice work Greg. I think it would look better on my side bar though.


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## Treecycle Hardwoods (Nov 3, 2014)

ironman123 said:


> That is some real nice work Greg. I think it would look better on my side bar though.


It is one of the pieces I will be attempting to sell thru the holiday season. If you wanted to buy/trade for it I would be down to work on something with you. Thank you for the Kudos BTW I appreciate it.


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## TimR (Nov 3, 2014)

Greg, this piece finished off and with a topper really made it come to life!! Looks great and your save with the lapis adds a bit of interest, as they say. 
Keep practicing with the cutter and it will only get easier.

Reactions: Thank You! 1


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