So, I have a real newbie question

Tom Baugues

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I guess I never thought of it before and now that I'm getting ready to try some....I don't know how.
Question......when turning a hollow form.......do you hollow away the center (pith) of a log or do you use a blank that was already cut away from the pith?
I'm guessing it can be done either way. So if you hollow out the pith of a log will it still split on the bottom?
 
...Question......when turning a hollow form.......do you hollow away the center (pith) of a log or do you use a blank that was already cut away from the pith?..

Hollow forms can be done several ways. Nearly all of the ones I've done have been done in a face (or side) grain orientation, like most bowls, so the pith has already been cut away from the blank.

If they are turned in an end grain orientation (where the grain is running parallel to the lathe bed), they can be either with or without the pith, although if the pith is there, it does increase the likelihood of cracking. I know some guys try to get around that problem by drilling out the pith and putting in a turned plug, but that's not really to my tastes, personally. Some woods, like Norfolk Island Pine, do pretty well turned end grain with the pith still in it. I've done a couple pieces of it that way and only had hairline cracking at the pith.
 
I am with Vaughn, I don't like end grain turning. I have been doing some cremation urns lately and my wood suppliers has been sending me blanks that are more conducive to end grain turning and the amount of checking I am getting is not a good thing. I am in the process of education him on this matter.
:gonnagetit:
 
Ditto what Vaughn said. I don't like doing a plug either when the pith is in the log. I turn it to final thickness and then soak it with CA. Never have had one crack on me. Using wipe on poly you don't even know CA was used.
 
Yep....

I do a fair amount of end-grain turning since we don't have big trees in my part of Texas. If the pith is going to be a problem, it is usually a problem from the start represented as a split or a ring check around the pith. I don't like wasting wood so I stabilize it with CA on the outside form one or more times during the shaping process. When hollowing, I typically start with a forstner bit to hollow out a void down to almost final depth. Then I drop thin CA in the bottom. Between the outside CA and the Inside CA...the problem goes away.
 
A bowl steady is very useful on a deep hollow form because it tends to wobble a tiny bit which can cause a catch. My first try at a hollow form is hanging on my shop wall in two pieces as a reminder. :(
 
pith or not pith

I know a guy who knows a guy.... who turns large > 10" dia and >24" tall forms. He does segmented and solid forms and in both types he installs a floating bottom. The bottom is flat and sits [not glued] in a recess with some space for movement. The bottom is held in place by a segmented ring.
Another turner I know says he makes his thin and very little troubles.
I go for thin and CA glue both sides.
 
Yep - i do not have large logs enough times to cut the pith out either and use what I have to do my turnings. The CA glue approach mentioned above by others works great and I have use it all the time.

There are times where I have turned a pc end grain (which i turn to completion in one session) where the pith is not only left in but it becomes part of the design in the side of the vessel (turned this way intentionally). If I do this type of vessel I will concentrate the application of the CA in pith and heartwood (in a small circle around the pith) and use a couple of coats pushing and working it in on the outside in a small diameter. On the inside i just dripple it in while its still in the chuck on the lathe - stopped of course - letting it dry well before preceding with the sanding. Then when done sanding i soak the inside with BLO and sit it "inside" to dry for several weeks. Finally I will finish it out however the mood takes me but I have had no cracks.

I am not turning to make a living out of turning so I have the time to let things dry and play around...............
 
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