This should keep me busy for a while!

[eyekode]

I finally finished making turning blanks out of the maple I picked up here.


Those blanks on the right are 12" diameter! That is the max my Jet 1236 can handle. And honestly it does not handle them very well .

Here is one of the bowls roughed out:


Now I just have to wait a year to see the final result .
Salem

 

[William Roscoe]

Nice flame! It will be a nice surprise in a year after you have forgotten how this looked and you put it back on the lathe. Looks like you'll have several nice surprises.

 

[Roy G]

Another aspect of all those blanks is that you would have spent maybe $30 each if you bought them. Good score.

Roy G

 

[eyekode]

There is some really nice wood in these! But they are the biggest I have ever turned. Any recommendations on how to chuck them? On smaller bowls I use a tenon. But the chuck manual says these are too big for a tenon and I should use a recess.

I plan on rough turning them to a thick inch, anchorseal, pack them in a bag with their shavings, and finish turning them in a year.

The first one I used a screw chuck on the top to make the a tenon on the foot. But then I chickened out, reversed the bowl, turned a tenon on the top, reversed the bowl and turned a recess on the bottom. After that I simply roughed it out. This is obviously NOT how I want to do the rest of the bowls.

I was thinking for the next I will: mount between centers, true the blank, turn a tenon on the top, reverse the bowl and turn a recess on the foot. Then reverse the bowl and use the recess to finish roughing it out. I can even leave the tenon on the top for truing after it dries.
Any alternate suggestions?
Thanks!
Salem

 

[eyekode]

I probably have more surprises then I can handle! Anyone want to trade bowl blanks?
Salem

 

[Timmy]

Very nice. I'm sure there will be some great bowls turned out of those blanks.

 

[caskey]

Depends on the chuck and jaws... i use tenons on stuff in the 24inch range

 

[eyekode]

Wow, that is huge! I have a supernova chuck with 50mm jaws. The manual lists 4" diameter x 6" length as the max sized blank when using a tenon. I have exceeded this on multiple occasions. It also says up to 12" diameter for recesses.

Maybe I should invest in larger jaws for these blanks? Or are they just in CYA mode in the manual?
Thanks!
Salem

 

[Gunslinger]

I think it is a bit of CYA with Nova, however, if you read instructions carefully a spigot to them is endgrain mount. Bowls are normally mounted face grain. A main consideration is the length, not the diameter; there are large leverage factors trying to tear the item out of the jaws the longer the item is.

For recess vs spigot it depends a lot on your design. I tend to stay with the 30-40% base guideline for bowls and use a recess about 90% of the time. If you want an artsy 12” bowl with a small base you will be forced to a spigot mount.
If you do the calculations (pi r squared) you will find the amount of wood which has to be broken off (dismount) is vastly different. A 2” recess with one inch of wood surrounding it has three times the area as a 2” spigot. Your 50mm jaws should be fine for anything up to your 12” diameter, be careful when you go wide and deep.

It may be the camera angle, but the Nova 50mm jaws do not use a dovetail in spigot use as shows in your pic. Spigots are cut completely straight with the standard jaws. Look for the one or two lines in your instructions which are all in capital letters.

 

[eyekode]

Oh my, you are right! I have been using a dovetail with these jaws for over a year. Doh! Only the very edge has a dovetail and that is probably just to bite in.
thanks!
Salem

 

[Gunslinger]

Eyekode said..
The first one I used a screw chuck on the top to make the a tenon on the foot. But then I chickened out, reversed the bowl, turned a tenon on the top, reversed the bowl and turned a recess on the bottom. After that I simply roughed it out. This is obviously NOT how I want to do the rest of the bowls.

I was thinking for the next I will: mount between centers, true the blank, turn a tenon on the top, reverse the bowl and turn a recess on the foot. Then reverse the bowl and use the reess to finish roughing it out. I can even leave the tenon on the top for truing after it dries.

I am making the assumption that by top you are referring to the pith side.
Although I don’t use them a lot, your wormwood screw in your chuck should hold it very very securely. Especially with tailstock support until it is rounded. I have a large forstner bit (3-1/4”) to flatten a shallow area to insure the top of the jaws seat firmly (I also use it for a base for my 3” faceplate). JMHO but I think the wormwood will hold much better than a tenon for roughing out. It also allows you to remove tailstock support for forming a recess or spigot.

In your last paragraph…I don’t understand the tenon on the top. Just turn a recess or spigot and reverse it to hollow out. A tenon on top would be turned away during hollowing?

 

[eyekode]

Have turned bowls both ways: pith at th bottom of the bowl and pith at the top. When I said top I meant the top of the bowl not the foot.

I like your idea of using a forstner for flattening. I may have to try that.

I do like using a wormwood screw and tailstock for truing the outside. But I didn't feel comfortable using the screw without the tailstock to form the recess. One issue is the minimum speed of my lathe is ~500 rpm.

About forming a tenon on the top of the bowl: I have heard of people doing this and then leaving a pillar of wood when they rough turn them. It can be handy to help true the blank after it dries.
Thanks for all the ideas!
Salem

 

[JRD]

Why wait a year?

I've had very good results after rough turning with DNA drying. Soak a blank in DNA for a day, let it air dry, then wrap in a paper bag with the interior of the bowl exposed to the environment. Sit it upside down on a wire rack so air can get to the interior surfaces. After about a month the blank will be at equilibrium with its environment.

This really works.

 

[eyekode]

I have been meaning to try this. Where do you buy DNA? How do you store it safely? Pour it back into the original container(s)?
Thanks
Salem

 

[kooshball]

Salem, I have bought DNA from the Sherwn Williams store on 64 by the High School.

I have been meaning to try this. Where do you buy DNA? How do you store it safely? Pour it back into the original container(s)?
Thanks
Salem

 

[cyclopentadiene]

How did you turn the blanks so round on your band saw? I usually just draw a circle on the bottom of the blank and cut an octagon with the chain saw. The first few passes with the lathe are a little work but it works.

I have only purchased a few blanks and all of these are perfectly round like the ones you have and it only takes about 20 minutes to have a bowl blank ready to dry as opposed to 45 from an octagon so the extra time in prep of the blanks may be worth the time savings. Also with unusual shaped blanks it takes longer as the speed of the lathe must be really slow and with a burl, it is a significant work while the lathe turns slow.

 

[eyekode]

My lathe can only swing 12" and I wanted to turn as large as I could. So I built a very simple bandsaw jig to cut the circles. Mine is just a piece of plywood with a rail that rides in the miter slot. Next I drew a line perpendicular to where the blade will cut and drilled holes every 1/4" up to a hair under 6". I use a nail driven through the appropriate radius hole and ground off to sit ~1/4" proud of the top of the jig.

To use the jig I turn on the saw and then ease the jig into the blade. When the holes line up with the the blade I clamp the jig to the table and start turning the blank on the pivot.

It worked great except that I do not have the appropriate blade for cutting cirlces in wet wood. I will probably end up buying highland woodworking's 3/8" band that is specifically for wet wood.

If you need pictures I can take some tonight.
Salem

 

[cyclopentadiene]

That sounds pretty simple. One of the vendors at the Woodworking Show in Charlott had a demo of a system that was for sale. The cost was about $170 which was a little steep for a one purpose jig. I like the idea of a plywood version. I have a 16" lathe and the largest that i can turn inboard is about 15" with my strategy. I have made a little larger by using the motor at the end and my mini lathe and the minilathe tool rest adjacent to turn outboard. Anything much above 16', the blank is too heavy to maneuver very well.

 

[eyekode]

If I were not trying to max out my lathe I would probably just round with a chainsaw too.

Here are some pictures of my cheap jig:

The jig clamped to my bandsaw: (note I don't even clamp it most of the time. A little adjustment can make it run smoother)


Closeup of the pivot:


And the bottom (I had to cut the miter bar to drill all my holes):

 

[JRD]

DNA is available at any of the Big Box stores. I usually pour it into a lidded plastic bucket, using the bucket for both soaking a roughed out piece as well as storage for the DNA until I need it again.