Setup and Use

This tool system is a refinement of many other hollow form boring systems.  It will allow you to have more control, consequently more fun and take the stress out of hollow form turning.  It can be seen by viewing  Hollow Forms - The Easy Way with Lyle Jamieson, a 90-minute video/DVD covering the set-up and use techniques for both the boring bar and laser systems produced by Phil Pratt is now available.

The system has three components:

  1. The Boring Bar system
  2. The Backrest system
  3. The Laser Measuring system

First, the boring bar has a dual function.  It has a hole in both ends for the swivel tip cutter assembly.  This gives you a straight boring bar on one end and a bent type boring bar on the other end.  Just flip the bar end to end.

The 90 degree rule must be kept in mind when you set up the system.  Never allow the cutting tip to cut at an angle of more than 90 degrees as it touches the wood.  If more than a 90 degree cut is made you are no longer scraping and you will get a catch.  To set the cutting edge angle to less than 90 degrees, place a straight edge of some kind on the top of the swivel tip holder and sight back along the boring bar to the support handle.  The tip should be parallel to the floor so that the tool cutting on the side of the vessel will not violate the 90 degree rule.

 

IMPORTANT!  When you have set the tool tip at the proper position, go back and grind a flat spot for all the set screws.  First, for the 3/8 tip assembly rod, and second for the boring bar at the stabilizer handle coupling.  At the other end, grind flat spots for both tip assembly and handle set screws.  The flat spots will help you set up the tip angle in the same place each time you move it and it is also a safety feature so the set screws don't slip with the twisting forces of the cutting action.

Use the swivel tip holder to position the cutting tip so that it points in the direction you wish to cut, straight ahead for cutting into the bottom of the hollow form or twisted to the side to cut the side on the vessel.  To make a cut set the cutting tip at the centerline of the hollow form.  How do you find the centerline when you are peering into a vessel and your view is blocked by the boring bar?  With the lathe off, score a line with the cutter tip from side to side on the bottom inside of your form.  Take the boring bar out and look with a light at the line.  Move the front tool rest up or down until the line is right on center.  I always bore a pilot hole to the proper depth with a forestner bit prior to starting my hollowing.

The stabilizing handle holds the boring bar in position. Again, this is set up to never violate the 90 degree rule.  The welded handle is not a precision instrument, it does not have to be.  The front tool rest will adjust to put the tip on centerline.  The handle does not take the stresses of the cut, the forces produced are down on the front tool rest.  The handle only stabilizes the position of the cutting tip.  The handle does not have to be perfectly straight or perfectly flat.  The system works because the cutting tip is positioned in the correct position to cut safely and easily.  The rectangular support of the boring bar handle will prevent any twisting.  The system removes any twisting force common to bent tools not supported in this manner.  You no longer need to place your tool rest way back behind the bent portion of your Stewart Bent tool (if you have one).  Slide the tool rest right up as close to the wood as you can.  The new tool handle will keep it from twisting or jumping.

The second component is a second backrest.  The most abuse the backrest will take is you leaning on it.  It too does not have to be high tech.  Keep it simple.   The impact of the cutting force is absorbed by the front tool rest.  The backrest should be positioned at centerline height.  When the boring bar handle is set on top of this new backrest it will be positioned a very little bit above centerline.  This will set up a very slight downward slope to the cutting tip.  This position will put the cutting tip at the cutting angle of less then 90 degrees.  Again, protection from getting a catch.  The backrest should not have height adjustment.  The front tool rest will give you the critical height adjustments to put the cutting edge right on center.  You'll find that this eliminates the nub or center cone-shaped protrusion in the bottom of your hollow form. 

Jamieson Backrest

The fingertip control that you achieve with this tool system allows thinner forms and smooth inside surfaces even when doing a piece with voids.  It is extremely easy to use, but there is an adjustment time needed for your body to get the "feel" of the new system.  When in use the new tool stays in the backrest.  The tool tip adjustments are done easily with the tool supported on both tool rests.  The same is true when you are sharpening, leaving the boring bar and handle cradled in the backrest.

Also, I have made David Ellsworth-type tools out of 3/8-inch steel rod - one bent and one straight.  Now they fit right into the boring bar for doing smaller pieces with a very small entry hole.  You can fabricate other bars to fit into the 3/4-inch handle.

The laser measuring system is the third component.  This is a whole new ballgame, see the laser page for details.

For turning deeper vessels I have designed a jumbo bar that is 1 1/8-inch diameter with a bent swivel tip assembly.  The jumbo bar can be used with the standard support handle and backrest.  Vibration is the enemy!  If vibration occurs a larger diameter boring bar is the solution.  Don't push the limits of any boring bar to the vibration point.

The set up and use techniques in my DVD, HOLLOW FORMS-The Easy Way 90 minutes long produced and edited by Phil Pratt, gives much more detailed help for both boring bar, backrest and laser systems. 

To Order Tools contact me at:

phone 231-947-2348

fax 231-947-2348

email lyle@lylejamieson.com

Now accepting credit card orders

 

No more white knuckling it.  No more sitting on top of your lathe.  No more fear of catches.  This

system takes both the mental and physical stresses out of hollow form turning.  Have fun!




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