Wood Turning Logo for aroundthewoods.com woodturning tips, techniques and instructions

Articulated Hollowing Tool for Woodturners

When normal hollowing tools will just not hit the right spot, an articulated one is needed. Making your own makes sense and makes cents.

One of the difficulties I have run into as some of the hollow forms I have been turning have gotten a little more complicated, is the reaching into certain areas, especially around the rim. I concluded that I needed an adjustable or articulated hollowing tool. The following is what I have come up with, although it is subject to a bit of tweaking. It seems to be working well.
scrap steel for cutting arm

First of all I hunted in the scrap bin and found a piece of 5/16" steel. 1/4" would have done but I work with what I have. It is mounted in a vise and marked to cut off a piece about 3" x 5/8" . I used an angle grinder but a hack saw would do fine if a bit slower.

steel woodturning tool shaft

Next I mounted a piece of 5/8" cold rolled steel rod and measured to cut off about 10".

woodturning tool shaft in vise ready for grinding

That piece goes back into the vise ready to have the end ground to a receiving platform. Again I am using an angle grinder but if you do not have one, it could be ground on the grinder.

receiving platform of homemade tool at angle 1 receiving platform of homemade tool at angle 2

Here are a couple of shots of the receiving platform ground to about the half way part of the rod and about 7/8" long.

The rod and bar

The rod and bar.

bar is cut to 2" long and the ends slightly rounded

The bar is cut to 2" long and the ends slightly rounded.

 bar is drilled on each end

Now to the drill press where the bar is drilled on each end, one to 13/64" to receive a tapping for a 6m x 1 bolt and the other to 15/64" to receive another bolt without tapping. Your bolt may vary in size so drill accordingly. The receiving platform on the rod is drilled to be tapped.

bar and rod are tapped as necessary

The bar and rod are tapped as necessary.

parts ready for assembly

The parts ready for assembly. From the upper left, a 3/16" cutting tip, 6mm washer, 6mm bolt, articulating bar, 6mm bolt, shaft.

assembled lower view assembled upper view

Assembled upper and lower view.

 mounted in a home made arm brace

Finally, here it is mounted in a home made arm brace, ready to be used. Any hollowing tool with the cutting tip so far from the angle of rotation will have a lot of torque so an arm brace helps to give control.

some changes to the hommade turning tool

Not able to leave well enough alone, I made a few changes. First of all I made a shorter arm and then changed from hex cap bolts to a pan head for the cutter and flat head for the arms. I also countersunk for the flat head screws. Here is, starting from the upper left, the cutting tip, washer, pan head screw, flat head screws, short arm, long arm, and shaft.

options for the articulated hollowing tool

I now have several options: long arm

short arm

short arm

both arms

both arms