by Cindy Boehrns

Turning a hollow form vessel  seems to be the next logical step to take once you have learned to turn an open bowl.  As I am a beginning turner, I have read many books and articles on turning hollow forms.    I have also spent a lot of time watching a great number of videos on the subject so I thought I would take a stab at documenting my experience.

I have found that there are many kinds of tools for hollow turning.   From a  simple straight boring bar with a carbide cutter to the captive tool systems there are many, many choices.  It seems to me that your choices are limited only by the size of your lathe and  the size of your  bank account.  I would suggest that before you start ordering hollowing  tools that you talk to your club mates and see what they use and recommend.   Many might be willing  to spend a little time with you giving you some  instruction or guidance and possibly some hands on time with their tools.    This will let you take a look at a wide variety of tools without making a large investment in a tool you may not be comfortable with.   Some may be willing to let you borrow a tool to give it a try at home..

To begin with you need to select a piece of wood.  I would suggest you keep it small about 5 inches in diameter and 5 or 6 inches long .  Mount your wood between centers and turn it round and true up both ends.  If you have a chuck,  turn a tenon on the end you want to be the bottom of your hollow form. If you don’t have a chuck, you can mount your blank on a faceplate or a  screw center but you should allow an extra inch or so  of  length to make sure you can get your bottom turned without holes in it.  This might be experience talking here but I will never tell.   You can also use a glue block.  Glue blocks allow you to use almost all of your wood and still have it held securely on the lathe.   I have found that by taking a parting tool and cutting several shallow groves  in the bottom of my blank,  it gives the glue some extra surface to grab.  I think  hot glue on a glue block is an excellent choice for mounting your wood,  especially smaller projects. I have never had one come off while turning and I cannot say the same for a chuck.  Most likely,  that was caused by operator error.   Make sure the glue is hot and after centering your wood on the block bring the tail stock up to apply pressure while it cures.  Remember you do not have a lot of time to get your wood on the glue block and centered, the wood is cold and the glue starts to set immediately and cold glue does not  make a strong joint.  I measure my glue block and draw a circle on my piece that is just slightly larger to facilitate centering.    It only takes 3 or 4 minutes  for a strong hold.    I would continue to leave the tail stock in place until you need to remove it to begin the hollowing.

Select the bowl gouge of your choice and begin to shape your form.  Take it slow you can always take more wood off  but you cannot put it back on once it is gone.  Possibly more experience talking here.   If you are using wet wood you will most likely be turning it a second time after it dries so while it is important to get the shape set where you want it, you don’t have to be concerned about tool marks as they will be removed and refined in the second turning.   There is also no need to sand at this time.  If you are using dry wood that will be turned only once,  you will want to put more time into making sure the shape is perfect and that you have turned it as smooth and as  free of tool marks as possible.  This will greatly reduce the amount of sanding needed.

After forming the outside,  it’s time to hollow the inside.  If the wood is wet and you will be re-turning the hollow form after it is dry, you will want to make sure that you hollow to an even wall thickness which should be 3/4 to 1 inch thick for this size.  You should leave the bottom thickness slightly thicker allowing for the foot.  If you are turning dry wood you  will be turning to your finished wall thickness.  Before you begin, you will want to drill a hole down the center of the form to a depth that is at least 1 inch short of the finished bottom.  If you remove the quill from the tail stock you can insert a Jacobs drill chuck with a morse taper into your tail stock .  There are several choices for a drill bit but remember that if you use a spade wood bit there is a screw point on this bit and you do not want to poke  through the bottom .  You can modify your spade bit by grinding  the screw off and shaping the bottom round. This shape when positioned at about a45 degree slant will serve as a shovel to help remove shavings as you turn.   If you do this I would use a bowl gouge to form a pocket in the top so that the bit will hold in place and not move off center as you start to drill.  Drilling on a lathe is quite different as the wood is turning and the bit is still. You will want to back the bit out frequently to remove shavings so you do not bind the bit.  Take my word for it you do not want to get the bit stuck  as it is very difficult to remove if you do.   More experience here.   How big of bit should you use?  The bigger the hole you drill the less you have to hollow out.   Once you have drilled your hole remove the tail stock and position the tool rest across the end of the hollow form  so the the tool will be cutting at center.  The positioning of the tool will be determined by the tool you are using.  Some will be held straight and level such as the Easy Wood Tools, and some will be held slightly down  such as scrapers and still others need to be at center with the bit at an angle .  This is the part where knowing your tool comes in.   Start turning with the tool in  the center hole and take light short even strokes moving the tool from the center to the outside, taking care not to get the wall too thin.  Always keep your tool in contact with the wood by  using push pull strokes.  This helps prevent the catches that can happen when you have to find the wood with each new  cut.  Remove your tool frequently to clear the shavings  and avoiding hitting the opening with the tool as you withdraw it.

If you have chosen to make a small neck opening you will need to turn up and under the top of the hollow form.  This will require a goose neck tool of some type.   I find that these tools are very easy to catch on the neck as you withdraw your tool so be careful.  It only takes a blink to blow up your hard work.   Be careful not to use the neck of your hollow form as  pivot point for your tool.

Continue working your way down and to the outside using a pair of calipers to check your wall thickness frequently as you go.  Make sure you use a depth gauge to check the bottom thickness as there are few worse feelings than finding a hole in the bottom when you go to part off your hollow form  More experience.  Sounds easy doesn’t  it.  Give it a shot.  It’s not that hard just a little scary when you cannot see where your tool is cutting.

I suggest that your venture into hollow forms by using your new  hollowing tool to hollow an open or nearly open bowl.  This will allow you to familiarize yourself with the cutting action of the tool by actually watching it perform as you turn . That would be difficult, or often impossible to do when cutting the inside of a hollow form.

There is, of course a lot more to hollow form turning, .  I have only turned a half dozen pieces but these are the basics steps I used.   Just remember,  the ultimate success of a vessel is determined by it’s form,  the time and patience you use to turn it,  and the sharpness of your tools .  Good luck and have fun!

Some Tips on Hollowing:

  • Measure wall thickness frequently. That’s especially true when you’re deep inside the vessel. Calipers, such as double-ended calipers are a must.
  • When using a glue block on an end-grain piece, you’ll get a stronger glue joint if you cut a small groves in the bottom so you have more glue surface.
  • Never allow the hollowing tool to touch the rim when cutting.  That’s a sure way to break the vessel when a catch occurs and it surely will.
  • When rough-turning wet wood keep the wall thickness fairly constant to help to avoid cracking as it dries.
  • If you plan to apply some sort of turned adornment, such as beads or grooves,  make sure you allow extra wall thickness.  It is really sad to cut your piece in half because you cut the wall too thin. and your beading tool cuts all the way through.  Cut your beads and grooves in the outside before you hollow and remember to allow for the depth of the bead cut.
  • Because you will be turning the walls thinner when you turn the hollow form the second time, you should complete all turning and sanding of the area around the rim when you are about 1/3 of the way down.  You don’t want the thin top wood to be unsupported for this process.  They suggest you go in thirds blending one section to the other before moving down.
  • For deeper pieces, a steady-rest is really a necessity. One can be shop-built using plywood and in-line skate wheels.  There are several resources on line for free plans.