Jamieson Deep Hollowing System

[cwearing]

Re: use for vases about 10-12 inches

May this system (or similar) take a green piece of wood from start to completion in one turning session? How significant will distortion of shape be with this procedure. Or, is it best to rough turn and rough hollow then drying the vessel for several months.

 

[Mark Mandell]

Depending on your cutter and boring bar size, any hollowing rig will do what you're asking about.

How the piece distorts as it dries has nothing to do with the rig, by rather with the wood, its grain orientation, and its structure. Any piece turned from wet to final form in one operation will distort.

Double turning hollowforms is done but it gets dicey because once distorted, getting good fixing on the lathe can be a fight. Personally, I turn to final shape and thickness and then let things go as they will before final sanding finishing.

 

[George Guadiane]

Depending on your cutter and boring bar size, any hollowing rig will do what you're asking about.

How the piece distorts as it dries has nothing to do with the rig, by rather with the wood, its grain orientation, and its structure. Any piece turned from wet to final form in one operation will distort.

Double turning hollowforms is done but it gets dicey because once distorted, getting good fixing on the lathe can be a fight. Personally, I turn to final shape and thickness and then let things go as they will before final sanding finishing.

Who would have thought I would agree with you so completely (on anything)?

The one thing I do with incomplete hollow forms is to put them back between centers and return the tenon. In that way, at least the opening I'm trying to hollow through is fairly true. This helps keep the opening smaller, which I like.
The advantage to hollow form shapes is that overall, their shape stays more uniform than an open bowl because the compounded curves helps reduce the amount of distortion. (I hope that made sense).

 

[Patrick Miller]

I just finished my first hollow form (6" diam- 11" deep) attempt using a my version of the L.J. hollowing tool. I asked Lyle the exact question this morning and he suggests turning green wood to completion. My method was to rough, dry and second turn but I didn't care for the results. Dried slightly distorted wood required that I remove more wood from the inside than I wanted and my fledgling skills meant more sanding than the wall thickness would allow. My next attempt will be to turn a green piece to completion. Lyle has been very helpful. As I have some metal working skills, I built my own bar, handle and back rest but purchased the cutter and hollowing video from him. His site and insight are excellent tools.
--pat

 

[Thomas Stegall]

The best approach depends on many different varibles including what you intend to have as your final thickness, what type of wood you are using, and what level of moisture it is at, since turning "green" is a very relative term. It may also depend on whether you have a form that will allow you to sand later or one that won't. And if you need the precision of a box the approach would be different than if you are doing an open ended hollow form were distortion is a visual concern not an issue of pieces fitting together. Generally, I turn with an endgrain orientation (often with the pith), so with most woods I get very little disortion when I turn green wood to final thickness. However, most of them are thin-walled turnings (.5 to 3mm), so there is little tension left in the wood to distort, but what is there can easily warp things because the thin walls are so flexible.

One of the ways to minimize disortion on thin walled turnings done to final thickness when wet, is to have a flare out or in at either end of the turning. This sudden change in the curve adds alot of rigidity to thin walls preventing distortion at the top and bottom (where it is most noticable). This is why hollow forms distort less than bowls as was mentioned above.

Most hollowing tools work easier on wet wood, and especially if your tool is extended far beyond the tool rest. The farther you extend the boring bar over the tool rest or the harder the wood, the more essential it becomes to turn green/wet wood. Hollowing the bottom to consistent thickness is also an issue to be intentional about. The thinner side walls regardless of grain orientation will dry faster than the bottom if you leave the bottom too thick, especially if you leave the chuck tenon on the piece.

 

[Jarred Hoffpauir]

Many of the hollowing tools on the market will claim to be the best tool out there and make hollowing easy and fun...The only thing that makes hollowing successful is trial and error. Pick a tool and use it, I use an eliminator and a crabtree hollowing tool along with a few others. The eliminator is great for its ability to sheer cut though it is a straight tool and can only do so much. I have a Crabtree 3/8 hollowing tool and it is great for how safe it is to use and the depth spring is great for finishing to thickness. I really want to try the Ellsworth tools but I have not purchased them yet. Maybe next month, but I believe they will be stable and cut nicely with the thick shaft and scraper.

If you are interested in more info on either of those two tools let me know. For full disclosure I do know the owner of Crabtree and am selling tools for him, I do think that its a good tool for what it is designed for.