Woodturner's Resource
Woodturner's Resource  
  • Featured Artist    • Websites   Support Wr
Tutorials, Projects & Tips   • Event Calendar   • Tool and Book Store
  Home Page Forum HelpSearch Map TPT Resources LoginRegister
 
Pages: 1 2 
Send Topic Print
Lg Bowl Wall Diameter... (Read 266 times)
 
John Grace
WR Addict
*****
Offline


Everyone needs a good
wingman...

Posts: 1,228

Bel Air, Maryland, USA
Bel Air
Maryland
USA

Lg Bowl Wall Diameter...
Jul 19th, 2021 at 10:38am
 
I'm beginning a commission for what will be my largest piece turned to date, a 20" diameter by 7" deep maple bowl.  As I've never turned anything this large before...does anyone have any suggestions with respects to wall thickness?  My 'gut' is telling me I should leave the wall somewhat thicker than I would for a 12-13" bowl but just thought I'd ask.  The obvious caveats being that assuming the blank doesn't crack or otherwise show any signs of breakage.  This will be the absolute maximum my NOVA DVR XP can handle so it should be interesting...not to mention long and arduous.  thanks...
Back to top
  

“If history were taught in the form of stories, it would never be forgotten.”  Kipling
 
IP Logged
 
Ralph Fahringer
WR Addict
*****
Offline


I'm the "Burly" Man!!

Posts: 1,599

Ellsworth, Maine, USA
Ellsworth
Maine
USA

Gender: male

PM3520b
Re: Lg Bowl Wall Diameter...
Reply #1 - Jul 19th, 2021 at 11:28am
 
Just visualizing a bowl that large... I would make it about 3/8" with a bit more on the bottom to keep the center of gravity down.

..and that is my 2¢. Smiley
Back to top
  

Originality is the art of concealing your source.
 
IP Logged
 
Ed Weber
WR Administrator
WR Patron
*****
Offline



Posts: 8,387

Wilton, California, USA
Wilton
California
USA

Gender: male

JET 1642
Grizzly G0584
Re: Lg Bowl Wall Diameter...
Reply #2 - Jul 19th, 2021 at 11:45am
 
Ralph Fahringer wrote on Jul 19th, 2021 at 11:28am:
Just visualizing a bowl that large... I would make it about 3/8" with a bit more on the bottom to keep the center of gravity down.


2 more cents
Back to top
  
 
IP Logged
 
Glenn Jacobs
WR Addict
*****
Offline


JC L&S

Posts: 1,913

North DFW, Texas, USA
North DFW
Texas
USA

Gender: male

Powermatic 3520C
Re: Lg Bowl Wall Diameter...
Reply #3 - Jul 19th, 2021 at 1:10pm
 
3/8 sounds good. Depends on species of wood and soundness of blank.

Glenn J.
Back to top
  
Glenn+J  
IP Logged
 
Jeff Vanden Boogart
WR Addict
*****
Offline


WR Rocks!

Posts: 881

Rural Green Bay, Wisconsin, USA
Rural Green Bay
Wisconsin
USA

Gender: male

PM 3520
Re: Lg Bowl Wall Diameter...
Reply #4 - Jul 19th, 2021 at 10:59pm
 
Biggest bowl I've made was ~15".  About 3/8" wall thickness, and it was a bit of a struggle because of warpage and chatter.  I'd probably go closer to 1/2" wall for a 20" bowl unless it really looked "fat".
Back to top
  
 
IP Logged
 
John Grace
WR Addict
*****
Offline


Everyone needs a good
wingman...

Posts: 1,228

Bel Air, Maryland, USA
Bel Air
Maryland
USA

Re: Lg Bowl Wall Diameter...
Reply #5 - Jul 20th, 2021 at 7:22am
 
Thanks all...it's going on the lathe this weekend.  We'll see how the roughing out process goes.
Back to top
  

“If history were taught in the form of stories, it would never be forgotten.”  Kipling
 
IP Logged
 
Ron Sardo
WR Administrator
WR Patron
*****
Offline


Chief cook and bottle
washer

Posts: 9,565

Drums, Pennsylvania, USA
Drums
Pennsylvania
USA


PM 3520
Re: Lg Bowl Wall Diameter...
Reply #6 - Jul 20th, 2021 at 8:08am
 
Quote:
I'd probably go closer to 1/2" wall for a 20" bowl unless it really looked "fat".

Smiley

It's easier to make it thinner than it is to make it thicker.



Back to top
  

Multimedia File Viewing and Clickable Links are available for Registered Members only!!  You need to Login or Register
WWW  
IP Logged
 
Ralph Fahringer
WR Addict
*****
Offline


I'm the "Burly" Man!!

Posts: 1,599

Ellsworth, Maine, USA
Ellsworth
Maine
USA

Gender: male

PM3520b
Re: Lg Bowl Wall Diameter...
Reply #7 - Jul 20th, 2021 at 9:55am
 
Quote:
It's easier to make it thinner than it is to make it thicker.





NOW YOU TELL ME!!!!!!  Smiley
Back to top
  

Originality is the art of concealing your source.
 
IP Logged
 
Ed Weber
WR Administrator
WR Patron
*****
Offline



Posts: 8,387

Wilton, California, USA
Wilton
California
USA

Gender: male

JET 1642
Grizzly G0584
Re: Lg Bowl Wall Diameter...
Reply #8 - Jul 20th, 2021 at 10:16am
 
Ron Sardo wrote on Jul 20th, 2021 at 8:08am:
Quote:
I'd probably go closer to 1/2" wall for a 20" bowl unless it really looked "fat".

Smiley

It's easier to make it thinner than it is to make it thicker.


The turning code has finally been cracked, way to go Ron  Thumbs Up
Back to top
  
 
IP Logged
 
robo_hippy
WR Addict
*****
Offline



Posts: 3,453

Eugene, OR, USA
Eugene, OR
USA

Re: Lg Bowl Wall Diameter...
Reply #9 - Jul 20th, 2021 at 11:24am
 
Largest bowl I ever turned was 22 inch diameter. Pacific Madrone is my favorite wood, and known for unpredictable warping and cracking before you fire up the chainsaw. It finished warping at 26 by 19 inches, kind of a D shape. With that wood, it needed to be kept to about 1/4 inch so it wouldn't crack. 3/8 is a good wall thickness for that size. Much thicker and it can 'feel' too heavy. 1/2 inch thick would depend on what type of wood it is. It can make a difference in drying it.

Sounds like you are planning to turn green to final thickness rather than twice turning. If the walls are too thick, it will crack. Also, in the transition area, the extra thickness there can make for uneven drying stress, which results in cracks. I have taken to a small ogee near the base to help even that out. Also, make sure to round over both edges on the rim as the sharp edge also makes for uneven drying stresses. Stretch film on the rim is good but not for maple. Seems I always get mold growing under the plastic with maple, all that sugar in the wood. Walnut is pretty stable, but cherry, if left 1/2 inch thick may crack.

What kind of wood is it?

robo hippy
Back to top
  
WWW  
IP Logged
 
Ralph Fahringer
WR Addict
*****
Offline


I'm the "Burly" Man!!

Posts: 1,599

Ellsworth, Maine, USA
Ellsworth
Maine
USA

Gender: male

PM3520b
Re: Lg Bowl Wall Diameter...
Reply #10 - Jul 20th, 2021 at 2:22pm
 
I did a 3 1/2"x 12" walnut bowl and made the walls 1/2" thick as the whole thing wanted to look massive...and it does. Smiley
Back to top
  

Originality is the art of concealing your source.
 
IP Logged
 
John Grace
WR Addict
*****
Offline


Everyone needs a good
wingman...

Posts: 1,228

Bel Air, Maryland, USA
Bel Air
Maryland
USA

Re: Lg Bowl Wall Diameter...
Reply #11 - Jul 21st, 2021 at 12:56pm
 
robo_hippy wrote on Jul 20th, 2021 at 11:24am:
Sounds like you are planning to turn green to final thickness rather than twice turning. If the walls are too thick, it will crack. Also, in the transition area, the extra thickness there can make for uneven drying stress, which results in cracks. I have taken to a small ogee near the base to help even that out. Also, make sure to round over both edges on the rim as the sharp edge also makes for uneven drying stresses. Stretch film on the rim is good but not for maple. Seems I always get mold growing under the plastic with maple, all that sugar in the wood. Walnut is pretty stable, but cherry, if left 1/2 inch thick may crack.

What kind of wood is it?


I prefer to 'twice turn' all of my pieces.  This wood is a 'silver maple' and is quite green as the tree was taken down within the past month.  The customer wants me to keep it as big as possible which means it could end up being 19+" in diameter and perhaps 8+" deep.  I've had good luck rough turning maple down to 3/4" wall thickness, re-sealing, and then storing my pieces on a high shelf in my garage.  I've tried any number of drying techniques and this, the simplest one, seems to work well for me here in MD.  Yes...I always rounded over the rim before storing and pay particular attention to the transition area.  One thing working in my favor is the size of the piece is so big I shouldn't have any difficulties with tool angle presentation, etc.  Either way, I'll find out for sure this Saturday once it goes on the lathe.  Definitely a chance for me to break out my large Robo tool rest.  Smiley
Back to top
  

“If history were taught in the form of stories, it would never be forgotten.”  Kipling
 
IP Logged
 
Don Stephan
WR Addict
*****
Offline


WR Rocks!

Posts: 2,502

Cincinnati, Ohio, Ohio, USA
Cincinnati, Ohio
Ohio
USA

Gender: male
Re: Lg Bowl Wall Diameter...
Reply #12 - Jul 21st, 2021 at 6:15pm
 
Check with the customer to make sure the total weight won't be an issue, or suggest a strength training program to use it.
Back to top
  
WWW  
IP Logged
 
Glenn Roberts
Senior Member
****
Offline


WR Rocks!

Posts: 381

Walworth, NY, New York, USA
Walworth, NY
New York
USA

Gender: male
Re: Lg Bowl Wall Diameter...
Reply #13 - Jul 21st, 2021 at 7:12pm
 
suggest a strength training program to use it.

Smiley Smiley  couldn't have said it better!
Back to top
  

The older I get, the better I was........
WWW  
IP Logged
 
Tim Tucker
WR Noob
Offline


WR Rocks!

Posts: 9

Re: Lg Bowl Wall Diameter...
Reply #14 - Jul 22nd, 2021 at 6:39am
 
This is the largest I have turned over the bed of my lathe. It is Camphor. I roughed it and sealed it until I ...grow a pair...and decide to finish it. Grin I want to tun it down to a rational thickness. But have not decided what that really means yet.

It is 25-1/4". The absolute max. on my lather 25-1/2"

Headgear/PPE is for a size reference.....
Back to top
  
 
IP Logged
 
Pages: 1 2 
Send Topic Print