Revisiting the Two Piece Hollow Form

Revisiting the Two Piece Hollow Form

Gordon Langer
In conjunction with our home club, the Edmonton Woodturners Guild, my good friend Brian McEvoy agreed to conduct two workshops covering one of his signature techniques, the Two Piece Hollow Form. I was thrilled to host the event in my shop and have Brian as the main attraction. As usual, he did not disappoint.

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Both days' classes were immediately sold out and the lucky participants had a great time learning first hand how to make a hollow form, which continually confounds people unfamiliar with the process to create it. Brian brought along some samples to provide examples of what can be done once the technique is learned.
 
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For the workshop we brought eight additional lathes to the shop and had eight people turning each day. Each day's sessions were structured the same way. Brian would demonstrate several steps of the process and then the group would go to their lathes and complete these steps. He was able to go to each individual for some "one on one" help if required.  

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We provided each participant with two birch blanks that Brian had previously cut into rounds. Prior to cutting, he had drawn pencil lines to create identical circumferences on both pieces and left the pencil lines showing. The significance of this will be apparent later.
 
Brian then explained how to carefully centre a faceplate on the blank. A great faceplate to use is the old Delta faceplate that has a centre hole, making mounting a breeze.  If you don't have one of these, be sure to take care to mount the blank dead centre.

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Here Brian mounts the bottom on the lathe.

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Next Brian turns the bottom to the desired form. In this workshop we decided to make a form resembling a curling rock. Brian demonstrates it with comparatively thick walls so that some embellishment, such as carving, could be done.
 
Brian also takes care to add a relatively small, shallow foot dovetailed to fit the the chuck so it can  be remounted to turn out the inside.
 
Be careful here not to remove too much of the outer edge of the blank, leaving the pencil line. As the bottom and the top will later be glued together it is important to have the outside of the blanks to be as close to the same size as possible. 

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Once the turning of the outside of the bottom is complete, it's on to sanding.  After power sanding with a coarse sanding disk Brian then hand sands to remove any "swirl" marks left behind from the power sanding, then on to finish stage.  In this case Brian sands to 1000 grit to give an ultra smooth finish.

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Throughout the demonstration the participants had the option to "get close" to see first hand some of Brian's techniques. We also had a camera going to provide close-up images so all could see.

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Next it was time to essentially repeat the process to the top, being sure to take care to turn a dovetail groove for the chuck.  When turning this, also leave a flat bottom groove for the chuck jaws to seat on. This will be sanded away later.  Again be careful here not to remove too much of the outer edge of the blank, leaving the pencil line.  As the bottom and the top will later be glued together it is important to have the outside of the blanks to be as close to the same size as possible.

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Once Brian completed the outside of both the top and the bottom of the project the group broke up and went to their lathes to start turning. After this step was completed by everyone it was time for lunch. While it was still a bit cool in Edmonton in early May we managed to have lunch on our deck. 

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After lunch it was "back to work" and Brian demonstrated turning the inside of the top.  This was kind of fun as everyone was able to go through the bottom on purpose! But first things first.

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The first step was to carefully create a flat edge along the outer part of the blank. Next remove some of the middle part of the blank but only enough to leave the flat edge proud of the rest of the blank. Next Brian takes great care to ensure the flat edge is exactly that - FLAT.  He uses a skew chisel to ensure the edge is flat,  then he uses a straight edge as this will be the glue joint when the two pieces are put together.  This may take a few attempts but is very important to get it right.

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Now for the fun part - turning out the centre and actually going through the bottom, but taking care not to touch the now perfectly flat edge.

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This process is repeated for the bottom BUT don't go through to bottom on that one! Now it's time to sand the inside of the top. Start with a power sander and then move on to hand sanding to 1000 grit or to your own finish standards. 

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This process is also repeated for the inside of the bottom.  When the sanding of the inside of the bottom is complete you can apply a finish of your choice.  For the purposes of the workshop we used a wax finish but just about anything would do.  At this point the group went back to the lathes to complete the insides of both the top and bottom.  

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Once everyone had the insides of their pieces complete Brian demonstrated the last steps of the process.
  
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With both of the inside pieces sanded and the bottom still mounted on the chuck, it's time to put the two pieces together.  It's wise to match the grain as best you can and make a pencil mark as a reference point.  This will help when you actually glue the two pieces together.  Once the alignment is made it is now time to apply yellow carpenters glue to both pieces on the flat sections you took such care ensuring both were perfectly flat.  
 
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Once glue has been applied to both surfaces, bring the tailstock equipped with a cone, shown here with a OneWay live center and use the tailstock as a clamp.  Be sure to apply adequate pressure to close any gaps that may show up.  If the two surfaces are flat then less pressure is required. Note: You may notice that this is not the piece featured in the rest of the newsletter, but I missed the (likely the most important shot) shot. So I had to resort to a stock photo.

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Once the glue has dried (normally about 30 minutes or so) it's time to sand the outside of the vessel. Again Brian uses a course grit to sand the glue joint and may make some minor modifications to the form. Once happy with the form he then moves to hand sanding to 1000 grit.

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An important part of the final sanding process is to remove the small ridge you turned on the top that you used to seat the chuck when turning the top.  This only takes a few minutes to ensure you have a smooth opening to the hollow form.
 
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The group then went back to work on the final steps of the project.
  
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If you ever have a chance, do take in one of Brian's demonstrations, as he is an excellent instructor and demonstrator. You won't be disappointed. At the end of each day, every one of the participants took home a piece I am sure they were proud of. Everyone had a great time and lots of fun.  
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Gordon Langer