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Hollow spiral turnings

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Blog entry by Don Butler posted 10-09-2009 11:16 PM 3315 reads 2 times favorited 8 comments Add to Favorites Watch

A while back I showed a small sample of how the Legacy Ornamental Mill works with a small spiral cane.
Turning those little things is a pure pleasure and I do it often.

But sometimes the demand is for a large spiral column.
This mill, model 1500EX is a long bed machine, signified by the EX in the model number. So I made the columns outside the front entry to our house/knit shop.

But there is an inherent problem with large, solid columns.
They split.
No matter what material is used (plastic excepted), it splits.
The process goes this way:
As the outer parts of the column dry out they contract.
Not much, but it doesn’t take much.
The inner core doesn’t contract at the same rate.
So the outer layers are now too small to cover the inner, unshrunken core.
Result?
Cracks.
Just look at the logs in a log house. Most of them split.

Most commercial columns are hollow, preventing the problem.

My columns are hollow, too.

Here’s how I do it.

I accentuated the lines showing the birdsmouth cuts that join the pieces in a six sided hollow form

Blocks are fitted to the column to fasten it in the mill. Then the form is milled round, first, and then the detail is milled in.

Here’s a short practice piece that didn’t have the birdsmouth joints, but does show the spiral forms.

The actual columns were finished outside with good primer and exterior gloss enamel. Then I filled the inside with foam to prevent moisture and insects from coming in.

Best regards,

d

-- No trees were damaged in posting this message, but thousands of electrons were seriously inconvenienced.



8 comments so far

View papadan's profile

papadan

1179 posts in 2834 days


#1 posted 10-10-2009 12:37 AM

Good information Don, you got my porch columns done yet? LOL

-- Carpenter assembles with hands, Designer builds with brains, Artist creates with heart!

View a1Jim's profile

a1Jim

115202 posts in 3043 days


#2 posted 10-10-2009 12:42 AM

Interesting blog

-- http://artisticwoodstudio.com Custom furniture

View Don Butler's profile

Don Butler

1086 posts in 2861 days


#3 posted 10-10-2009 12:51 AM

Dan,

I don’t recall that order. When did you send it?
LOL

d

-- No trees were damaged in posting this message, but thousands of electrons were seriously inconvenienced.

View Mark Shymanski's profile

Mark Shymanski

5314 posts in 3178 days


#4 posted 10-10-2009 12:52 AM

Very interesting, thank you.

-- "Checking for square? What madness is this! The cabinet is square because I will it to be so!" Jeremy Greiner LJ Topic#20953 2011 Feb 2

View Loucarb's profile

Loucarb

2388 posts in 2911 days


#5 posted 10-10-2009 01:03 AM

Thanks for sharing that is very interesting.

View Dan'um Style's profile

Dan'um Style

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#6 posted 10-10-2009 01:44 AM

Good one Don! that mill sounds like a cool toy…

-- keeping myself entertained ... Humor and fun lubricate the brain

View cabinetmaster's profile

cabinetmaster

10874 posts in 3024 days


#7 posted 10-10-2009 02:07 AM

Wow. Just when I need to do a 9” X 52” hollow column, someone makes a post. I like that Idea. It sure would save on a major glue-up. Plus I have to split it to go around a 4 X 4 post. I hope you don’t mind me using this idea.

-- Jerry--A man can never have enough tools or clamps

View Don Butler's profile

Don Butler

1086 posts in 2861 days


#8 posted 10-10-2009 02:08 AM

Not at all.
Please do.

-- No trees were damaged in posting this message, but thousands of electrons were seriously inconvenienced.

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