Fourth hollow form attempt - Woodworking Talk - Woodworkers Forum
 
Thread Tools Display Modes
post #1 of 19 Old 04-29-2012, 11:15 AM Thread Starter
Firewood Inquisitor
 
sprior's Avatar
 
Join Date: Aug 2008
Location: Danbury, CT
Posts: 437
View sprior's Photo Album My Photos
Fourth hollow form attempt

Started with this oak log in my lathe yesterday, it just barely fit and I had to use my sawzall to cut off a small bump so it wouldn't hit the bed.

Name:  ForumRunner_20120429_110845.jpg
Views: 363
Size:  48.4 KB

I finished the day with this. I've managed to hollow down the center to almost the middle, but there's a lot still to do.

Name:  ForumRunner_20120429_110903.jpg
Views: 258
Size:  44.7 KB

This is my fourth attempt at a hollow form, i still consider it a long shot that it will survive without cracking or something else, but it's been a lot of practice so far.
sprior is offline  
Sponsored Links
Advertisement
 
post #2 of 19 Old 04-29-2012, 11:16 AM Thread Starter
Firewood Inquisitor
 
sprior's Avatar
 
Join Date: Aug 2008
Location: Danbury, CT
Posts: 437
View sprior's Photo Album My Photos
It's about 11 inches tall and wide.
sprior is offline  
post #3 of 19 Old 04-29-2012, 12:50 PM
Senior Member
 
Join Date: Aug 2010
Location: North Carolina
Posts: 1,021
View NCPaladin's Photo Album My Photos
Looking really good so far. Are you doing anything to slow the water loss from the endgrain? I haven't tried anything that large but in Michael O'Donnell videos he use water in a spray bottle to keep the outside from drying out.
Hope you get it finished without any cracks.
Should be a beaute.

They who can give up essential liberty to obtain a little temporary safety, deserve neither liberty nor safety. Benjamin Franklin
NCPaladin is offline  
Sponsored Links
Advertisement
 
post #4 of 19 Old 04-29-2012, 01:15 PM Thread Starter
Firewood Inquisitor
 
sprior's Avatar
 
Join Date: Aug 2008
Location: Danbury, CT
Posts: 437
View sprior's Photo Album My Photos
Thanks. I haven't done anything to slow drying, in fact I realized this morning that I should have dropped the whole thing in the garbage can I had the wet shavings in, but I didn't. I haven't got a clue what I'm doing for a lot of this, I'm trying to learn though. I don't think I've been unsafe though, I used a 4 1/2" faceplate with 8 screws and kept the lathe at 100RPM for most of the outside, 200RPM later. I hadn't even decided on what shape I was making until I got the outside round, for a while I was considering making a lamp shade and then I just felt like making a globe.
sprior is offline  
post #5 of 19 Old 04-29-2012, 02:50 PM
Senior Member
 
Join Date: Sep 2007
Location: Baxter, Tennessee
Posts: 3,257
View john lucas's Photo Album My Photos
If your going to spend that much time hollowing work that size take the time to try and save it. At the very least put it in a box with the lid closed.
You can put whatever finish you are going to use on the end grain sections, that will slow down the moisture loss and hopefully even out the drying.
I know some people have been successful leaving the pith in. I haven't. It just invites cracking. You need to seal the pith inside and out and about 2 inches on either side of it. That will help but no guarantees.
I would also seal about an inch inside and out at the rim. That's where many of the checks starts. Why, because water can leave that area faster. When one part of the wood starts to dry and shrink and the wood right beside it doesn't it cracks.
If you really really want to save it put it in a plastic bag. Turn the bag inside out every day. This really slows down the moisture loss but can if you don't turn it every day, cause mold. As soon as you see any mold starting wipe or sand it off. After a week or so you can put it in a box with the lid lightly closed.
Putting it in a bag with shavings just promotes mold. It does slow down the drying time but so does a lack of air movement such as putting it in a box, the box doesn't promote mold like shavings do.
john lucas is offline  
The Following User Says Thank You to john lucas For This Useful Post:
sprior (04-29-2012)
post #6 of 19 Old 04-29-2012, 04:24 PM Thread Starter
Firewood Inquisitor
 
sprior's Avatar
 
Join Date: Aug 2008
Location: Danbury, CT
Posts: 437
View sprior's Photo Album My Photos
Hadn't even thought about a finish yet. I've got mineral, walnut, and tung oils, poly, mylands friction finish and wax and spray lacquer. Any suggestions for this oak piece?
sprior is offline  
post #7 of 19 Old 04-29-2012, 08:21 PM
Senior Member
 
Join Date: Jan 2011
Location: McKinney, Tx
Posts: 763
View Bonanza35's Photo Album My Photos
Looks really cool. That's a huge undertaking hollowing out something that size. Good job getting this far with no cracks. It's funny, I just cut a big oak blank today with similar intentions. Just waiting for a full day to tackle it.
As for finish, I like a very low gloss on oak personally. Of your options I'd go with just one good coat of tung oil.
BTW, what kind of wall thickness did you go with?
Bonanza35 is offline  
post #8 of 19 Old 04-29-2012, 08:33 PM Thread Starter
Firewood Inquisitor
 
sprior's Avatar
 
Join Date: Aug 2008
Location: Danbury, CT
Posts: 437
View sprior's Photo Album My Photos
I'm not down to the final wall thickness yet, but I was planning to go for something around 1/8", more at the bottom. And if you're doing something this big then 1 day isn't going to cut it. I spent 4-5 hours on it yesterday and a few hours today and just got tired of holding onto the hollowing tool for dear life - there's a knot in the inside (doesn't come to the surface) that I've been banging my Rolly Munro hollower against. I'm just happy that I don't have a mark on my side from bracing the tool against my body while doing all that. I did make a lot of progress today, the form is a lot more hollow now, but I've still got lots more to do on the sides. The outside surface was a bit dryer today so I could get some sanding done and get rid of some tool marks. I also noticed that wet oak seems to start surface rust on the lathe bed really quickly, so I spent some time sanding down the bed and coating it with wax.
sprior is offline  
post #9 of 19 Old 04-30-2012, 10:06 PM Thread Starter
Firewood Inquisitor
 
sprior's Avatar
 
Join Date: Aug 2008
Location: Danbury, CT
Posts: 437
View sprior's Photo Album My Photos
Still so far so good, no cracks and I've been hollowing out more each day. Last night I left it filled with shavings, but after doing more tonight I coated the outside with walnut oil and a little inside near the rim and then wrapped it with a plastic trash bag. Hopefully that'll keep my luck going.

Any opinions on the max average wall thickness I can finish with? 1/8" is starting to feel like it'd be hard to manage.
sprior is offline  
post #10 of 19 Old 04-30-2012, 10:27 PM
Senior Member
 
Join Date: Sep 2007
Location: Baxter, Tennessee
Posts: 3,257
View john lucas's Photo Album My Photos
The safest thing to do right now is to put a plastic bag over it each time you leave it alone. That will sort of hold it in suspended animation and keep it from cracking. No moisture can leave it that way. Don't leave it real long or it can start to mold but a day or so is fine.
Just about any finish will work although I don't have very good luck using friction polishes on large pieces.
john lucas is offline  
post #11 of 19 Old 04-30-2012, 10:48 PM
Slightly seasoned amateur
 
WeekendTurner's Avatar
 
Join Date: May 2011
Location: Raleigh, NC
Posts: 118
View WeekendTurner's Photo Album My Photos
Send a message via AIM to WeekendTurner
Wow. I have the same Nova lathe and would not have dreamed of mounting a log that thick. It looks like you didn't even have clearance to spin that thing without chain-sawing it down a bit. The swing over that bed is only 16" if its what I think it is, and that log has to be more than 15" diameter.
Is it chucked yet or is hat a faceplate mounting?

Really impressive so far.
WeekendTurner is offline  
post #12 of 19 Old 04-30-2012, 11:23 PM Thread Starter
Firewood Inquisitor
 
sprior's Avatar
 
Join Date: Aug 2008
Location: Danbury, CT
Posts: 437
View sprior's Photo Album My Photos
Thanks WeekendTurner. That log really was the biggest possible without some custom bed modifications. I'm using a 4 1/2" faceplate with 8 screw holes and 1 1/2" screws. When I first attached the faceplate to the headstock I was amazed that it rotated smoothly with no resistance even before I brought the tailstock up. The log just cleared the bead except for one bump which I took off with the sawzall. The banjo would not fit under the log so I started with it perpendicular to the bed at the tail end and the rest extending over the end of the log. Then once I turned off the bark the banjo would fit under the log and I gradually worked my way to the head end of the log. The end grain at the tailstock was tricky to turn evenly, but I managed. Finally I got the banjo all the way to the head end and could turn the head end to the rounded shape. I turned the entire outside of the log at 100RPM and it took about an hour and a half, maybe a little more. Thi is the only time I've noticed the motor on the Nova DVR XP to even feel a little warm. Then when I started hollowing the blank was still pretty darn heavy so it's still impressive that the bearings on the headstock are up to the task. Now anyone who knows better will suggest that you do the initial hollowing with a drill and work from there. I didn't have a drill bit for that so I just started working with the Munro Hollower2 right from that initial hole. I feel it gave me a lot of experience getting the motion right to trim off the cone that tends to form at the bottom center since I did it all the way down, but would have been faster if I had drilled first (I've gotta order one of those big honking drill bits which fit in a MT2). I found that the lathe which is at a good height for spindle turning was a little low for doing this hollowing so I'd end up standing at the tail of the lathe with my legs spread apart a bit and I'd end up moving my hips forward and back to get the motion to trim off the cone at the bottom - I was pretty sure my wife was going to walk into my shop and catch me humping my lathe...
sprior is offline  
post #13 of 19 Old 05-01-2012, 10:20 PM
Senior Member
 
Join Date: Feb 2012
Posts: 997
View BigJoe16's Photo Album My Photos
That looks great! Watch out for warping. Green would likes to warp and twist as it dries. It will be hard to finish turn something that thin if it warps.
BigJoe16 is offline  
post #14 of 19 Old 05-01-2012, 10:26 PM
HALL OF FAMER
 
Kenbo's Avatar
 
Join Date: Sep 2008
Location: Toronto, Ontario, Canada
Posts: 8,209
View Kenbo's Photo Album My Photos
Well, you're one up on me. I've never tried anything like that before. I may have to put it on my bucket list. Great looking stuff.

There is a very fine line between a "hobby" and a "mental illness"
Kenbo is offline  
post #15 of 19 Old 05-01-2012, 11:12 PM Thread Starter
Firewood Inquisitor
 
sprior's Avatar
 
Join Date: Aug 2008
Location: Danbury, CT
Posts: 437
View sprior's Photo Album My Photos
OK, After hollowing for a few days I did as much as I can stand and turned the form off the lathe. I used a detail gouge to finish the bottom shape and turn a slight indentation. I then made the tenon off the faceplate as small as possible with detail gouge, skew, and finally parting tool. I then cut off the tenon with a hand saw, put the form upside down on a pad on the floor and used an angle grinder to get rid of the rest of the tenon. The pith goes through the middle of the bottom so I flooded it with CA and then later coated the bottom and inside with walnut oil.

The walls start around 1/4" thick at the rim and gradually get thicker going down, the bottom is still fairly thick and heavy - this form isn't going to tip over when you put something tall in it.

So the final option is that I have a bucket of denatured alcohol which I think this form would fit in. Should I try doing an alcohol soak or let this form dry slowly with a coat of oil on it?

This has bee quite an experience and I'm glad I did it. So far turning has been about more immediate gratification - a pen, or since I define rough turning and finish turning a bowl as separate projects. This project pushed my patience a bit.
Attached Thumbnails
Click image for larger version

Name:	IMG_7400.jpg
Views:	166
Size:	91.6 KB
ID:	43939  

Click image for larger version

Name:	IMG_7401.jpg
Views:	143
Size:	97.2 KB
ID:	43940  

Click image for larger version

Name:	IMG_7402.jpg
Views:	132
Size:	98.2 KB
ID:	43941  

sprior is offline  
post #16 of 19 Old 05-02-2012, 08:10 AM
Member
 
Join Date: Apr 2012
Posts: 33
View clapiana's Photo Album My Photos
nice job! that is chunk of wood that you started with. what did you use to rough the outside of that hollow form? are you only using the munro on the inside?
clapiana is offline  
post #17 of 19 Old 05-02-2012, 08:24 AM Thread Starter
Firewood Inquisitor
 
sprior's Avatar
 
Join Date: Aug 2008
Location: Danbury, CT
Posts: 437
View sprior's Photo Album My Photos
I used an Ellsworth bowl gouge for the outside and just the Munro tool for the inside.
sprior is offline  
post #18 of 19 Old 05-02-2012, 08:51 AM
Member
 
Join Date: Apr 2012
Posts: 33
View clapiana's Photo Album My Photos
ok makes sense.

thanks for the posts i am really enjoying seeing your hollow form progress
clapiana is offline  
post #19 of 19 Old 05-02-2012, 11:38 AM Thread Starter
Firewood Inquisitor
 
sprior's Avatar
 
Join Date: Aug 2008
Location: Danbury, CT
Posts: 437
View sprior's Photo Album My Photos
Thanks. I'm happy with this project (it'll be better if it manages not to crack). It started becoming "work" when I was hitting a few embedded knots in the wood - with the Munro tool I was getting pretty beat up trying to handle those. It got a little better when I adjusted the depth stop to an even shallower cut. I'm also planning to order some long MT2 drill bits so I don't have to spend add much time dealing with the center nub. I think that will keep me less tired when I get to the edge finishing when the most patience is needed. The final thing on my someday wish list it's a compressor with a bigger tank so it doesn't have to refill every time I blow out the shavings on a big piece - that's a lot of noise.
sprior is offline  
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Woodworking Talk - Woodworkers Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Similar Threads
Thread Thread Starter Forum Replies Last Post
First hollow form attempt sprior Woodturning 26 04-15-2012 11:20 PM
Hollow form CB&D Woodturning 8 08-04-2011 11:23 AM
Hollow Form Jeff4woodturning Woodturning 6 11-16-2009 11:15 PM
Birch Hollow Form Bill Bolen Woodturning 11 05-12-2008 12:52 AM
First Hollow Form jbksman Woodturning 7 02-08-2008 09:18 AM

Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

 
For the best viewing experience please update your browser to Google Chrome