Large Segmented Bowl - #2 Making the Base

Because there are a lot of cuts that have to be precisely made I started out by running a check of the table saw blade to make sure it was cutting square to the table.  First step is to cut a couple of scrap pieces that have parallel long edges then stand them on their cut edges like below.  The green tape is my cutting reference mark set against the crosscut fence.  Everything looks good on the left image but if you rotate the left board 180 degrees then the out of square becomes visible as shown on the right image.

Looking closer the below left image shows how much the blade is out-of-square.  Some minor adjustment of the blade, in this case rotating the blade to the right brings the pieces together and all is square.

A trip into my wood storage gave me a good group of cherry and walnut pieces to start with.

In the last post I decided to float a center panel in the bottom bowl layer.  The top image below shows a section through the bottom.  For reference the center panel is just under 3/16" thick.  To make the slot I made one pass on the table saw then moved the fence slightly to get the slot width I needed and made a second pass.  The bottom photo shows that setup.  The yellow and black thing is my magnetic fence.  I set it up to apply a slight pressure to keep the board pressed against the rip fence on the right.

Once the slot is cut I can start on cutting the wedge-shaped pieces that will get glued together to make the bottom layer.  Here is the jig with the slotted bottom blank in place.  I will use the jig to cut 18 pieces for each of the 16 rings that will make up the bowl.

This is the first cut which gives me one side of the wedge and a triangular waste piece.

Before making the second cut I flip the piece 180 degrees so the slot that was facing me now is away from me.  The piece is then slid to the right and clamped in place at the Outer Face Length I obtained from the spreadsheet. 

A stop that has a matching angle is then clamped in place so I can make all 18 pieces the same size.

 

The cut is made and I have one piece the right size.  For those of you with sharp eyes this first piece is not from the same place in the board as the previous photo.  That’s because when I checked the piece’s size it was a couple hundredths of an inch small.  I must have bumped the stop or something else.  Anyway, I reset the stop, recut the first angled side and made the cut you see here to get the right sized piece number 1.

Now it’s on to the second piece.  Because of the slot there is a specific inside and outside to the pieces.  This means that I have to flip the board 180 degrees back to its original position, cut a new first taper in the top view below then in the bottom view flip the board 180 degrees, push it up to the stop and make the second cut to get the second completed piece.  Two down and 16 to go for this ring.

In the image below, I have the first four pieces cut and arranged along with the waste triangular pieces.  The other layers without a defined inside and outside will be cut without flipping thus eliminating the waste triangle resulting in less waste. 

With all 18 pieces cut I made the floating circular panel and did a test fit.

To make the center disk float in the slot it could not be glued in-place and that presented a problem.  Gluing up the rings is a really messy process and glue gets EVERYWHERE.  There is no way I could glue the ring up and not get any in the slot which would glue the disk permanently in place losing its floating attribute.  I thought about doing a two-step gluing process where I would only glue up half the ring at a time then insert the disk and very carefully glue the two halves together.  Sounds good but if the slots are not aligned dead on then there would be no way to get the disk in place plus I would probably still have glue to clean out of the slot so the disk would fit.  A couple of other ways all had their problems too.  What I finally ended up doing was to finish the disk and the slots before the gluing all the pieces together.  Here you can see the disk and ring sections prefinished with shellac where I do not want the glue to stick.  Now when I do the actual turning I think that much of the finish will be removed but the slot to disk surfaces should not be permanently glued together.  At least that’s the theory.

Gluing up this many pieces, getting them aligned and clamped can best be described as semi-controlled chaos or a mad race against time before the glue sets.  According to the time stamp on the photos it took me right at four minutes from the time I started applying the glue until everything was together and the glue mess cleaned up.  I have to say that a couple of dry runs beforehand did not hurt my time either.

Here the first ring, which is the base with the glue-up finished and ready to set overnight before proceeding.

The next day the clamps are removed and several light passes made through the thickness sander to obtain the needed flat parallel faces.

Next up – Face Plate Sandwich, Making/Attaching Layers & Turning

Large Segmented Bowl - #1 The Beginning

In a recent trip to Santa Fe, NM I saw some large segmented bowls in various Native American motifs.  I have made several segmented pieces (below) but nothing larger than about 11” in diameter. 

Intrigued I wondered what making a bowl that pushed the limits of my lathe would entail and what kind of obstacles I would encounter.  Since my lathe has a maximum turning diameter of 20” I decided to shoot for a finished diameter of about 19”.  Working in SketchUp I created my finished shape paying no attention to the size but concentrated on what the profile should look like.  Most of the pieces I have done have had a fairly small opening.  In this piece I wanted to go with a design that is reminiscence of a wide mouth storage container.  When I got something that I was happy with I scaled it to be 19” in diameter.  With that done I measured the height and found it to be about 12”.  Here is the piece in profile and looking down  slightly.

Next is to create a section as though one had sawn the bowl in half vertically .

With that done and deciding to use ¾” thick rings except for the bottom I could lay out each layer’s  diameter and segment width.

The next decision is to decide how many segments to make each ring out of.  To give me some help in this I turn to a spreadsheet I made.  Once I enter the radius of each ring it shows the Outer Face Length for each segment by ring in a variety of segments per ring.  For this piece I chose to use 18 segments  per ring.

Taking this information, I can use another set of calculations to get the particulars of each piece in each ring plus the total blank size I will need to cut the ring segments from.

 The headings like "Outer face length" in the above calculations are based on the drawing below.

To get an idea of what the piece would look like when done I built each ring using cherry for the body  and walnut for the feature pieces.  Here are a couple of views on what that looks like.

The unturned rings give a pretty good idea what the finished piece will look like but I wanted to get a better representation as I had two different designs I was considering.  That required me to intersect the unturned rings with the smoothed profile.  I have to say for the computer to calculate  the intersection of all those facets it did take some time.  I probably could have gotten by without doing this but I could so I did.

Once I had decided on the feature pieces size it is back to the spreadsheet to set up the last two  columns to calculate the blank length needed for the cherry and walnut pieces.  While it looks like everything is set in stone that is not really the case.  As I build the bowl adding the rings and turning if things do not look right I can and will make changes.

I usually do a double check on the Outer Face Length by taking the drawing one step further to see what it comes up with.  Below is a copy of that drawing.  If you compare it to the spreadsheet there is a difference of a few hundredths of an inch but that does not really worry me as for making the rings is it within tolerances.  If there is a big error then I need to take a look and see why.  It is my guess that when  SketchUp gets into that fine a measurement then it may not be as precise as the spreadsheet which carries out the calculations to a whole slew of decimals.  It’s 15 places if you are interested.

One more detail needs to be addressed and that is where all the pieces come together in the bottom layer.  There are 18 pieces so that’s 36 cuts I have to make and have them all come at an exact center point.  Now I am pretty meticulous when it comes to setting things up but if I am off by even 3 thousands of an inch then when the pieces all go together then there is going to be a gap of just over a tenth of an inch.  I could cut or drill a circle in the center then put a plug in but have had some problems with that.  Since wood moves around with humidity changes what usually happens is the piece cracks or ends up with a hairline gap.  This is going to be a pretty big piece and as such the wood movement is going to be more so I decided to take a page from cabinet making and float the center piece in a slot.  It is similar to a raised panel door where the panel floats in a frame.  Here is what a section through the bottom would look like with the slotted pieces and disk in place.

Next up – Making the Base

Rifflers Handles & Case - #6 Top Part 2 & Finishing

Next is to make risers that go between the dividers and a cross brace that will go inside the lid.  The risers will lift the riffler’s cutting surface up and make them a little easier to grab.

The grain in both these pieces are a little different than what you would usually find in pieces like these.  So as not to have a cross grain situation the long edge will be end grain.  The blanks are cutoffs I saved when making the end piece blanks.   I used a router with a 3/8” round over bit to cut the top and bottom ending up with a bullnose edge.  Here is the setup on the router table.

To cut the riser and brace off I used the table saw with a slightly different setup.  Rather than measure between the fence and the blade for the kept piece I set the fence so the cutoff was the kept piece.  This is because the kept piece is not very wide and has a rounded edge that I thought might roll a bit as I made the cut.  If that happened the blade could grab it and that would be a bad thing.  Making the cut as shown below gives a nice wide flat surface to hold onto while making the cut.

With the riser blank cut I could start cutting the individual pieces that go in the base.  Below is a photo that has the whole blank with the riser cut off, it set in place in the base and a close-up.

With the piece length verified I clamped a playing card to the fence as a stop making the cut just a little long.  I used the card rather than a regular block because I was worried that because the cut-off was the piece I kept with a regular stop it could get pinched between the stop and the blade.  If that happens things can get really exciting in a hurry and not in a good way. 

The pieces are cut just a fraction long because as careful as I was when setting the divider spacing there are minor differences.  No more than a couple hundredths of an inch but enough I wanted to be able to fit each one exactly.  Final fitting is done with a 12” disk sander and a miter gauge to keep the face square. 

The only thing of note as I glued the risers in was the use of a spacer to make sure when done they were all lined up straight.  A single similar piece will be made for the top that will act as reinforcement.

Next is to round over some of the edges.  As a way of assuring that I routed just the edges needed I marked the cut edges with chalk.  I will be holding the routed pieces in all different directions and it would certainly be easy to get confused and route an edge that should not be routed.  Here is the lid marked and ready to go.  The roundover bit in the router is a 1/8” radius.

 

Here is the lid on the base after routing.  The corner circled in red is end grain and is so small I was concerned that if I used the router to make the cut the odds of a mishap were pretty good.  It was pretty easy to use sandpaper to match the radius and blend the two edges.

The pins that will hold the top in place and allow it to open are next.  I wanted to make the pins out of ¼” diameter brass rod and had a heck of time finding it.  I finally found a brass rod threaded on both ends that was a replacement part for a water filler for a stock tank.  As an added bonus the treaded ends will work to help keep the pins in place.  With the top held in place with spacers I marked the pin length and cut it off with a hacksaw.

Once cut I chucked the pin up in the lathe, used a fine file to shape and bring it to the proper diameter as the rod was a bit oversize.  From there I used sandpaper starting with 320 and ending with 1,500 wet then on to steel wool.  Final work is with a cloth wheel loaded with polishing rouge which gives me a fairly polished surface. 

For feet I used the same process except using a file I cut a decorative groove just above the bottom.  The little feet will be installed in a ¼” holes in the base.  Below are all the brass pieces for the project.

Next is the marking and drilling of the holes for the brass pins.  These need to be carefully measured so the holes line up on each side.  To hold the top and bottom together while drilling I shimmed the gap between the two pieces then taped everything in place.  With that done I moved to the drill press, clamped a tall extension board to the fence, checked for square, made sure the drill was lined up with the center mark, clamped the piece in place and drilled the hole.  With one hole done I flipped the piece keeping the same fact against the fence and drilled the other side.  Below you can see the total setup plus a closer view.  The depth of the holes is critical as the pins need to bottom out in the holes so when they are installed they only go in so far.  With this design there is no way to get them out if they get pushed in too far.  The last bit of woodworking is drilling holes for mounting the feet in.  I used the drill press using the process as above.

Finishing is next.  I am using Danish Oil rather than my usual lacquer finish because I think that over time the case could get a little beat up.  If that happens I can refurbish it by applying another coat of oil.  I started with the top to get a feel for how the wood will react with the finish.  Here is a photo of the top with one coat and the bottom with none.  This gives a good idea of how the finish brings out the grain and richness of the walnut used.

Once the finishing was done I installed the feet.  The piece of wood with the hole in it is my stop.  I put some epoxy in the hole, the foot in the spacer and use a clamp to press the foot flush with the spacer.  Follow the same process and presto all four feet are set at the same level.  At least that was the plan.  I must have bumped one of the feet as I was cleaning the squeezed out epoxy off.  I ended up with one being just a little to deep.  Once the epoxy has cured the fix was pretty easy, I clamped a full sheet of sand paper down then rubbed the piece back and forth until everything was level.

With the feet in, the last thing was to glue in the pins.  I used yellow carpenters glue rather than epoxy because this is a one shot install.  As I said once I push the pins in there is no way to get them out.  I expected some squeeze out of glue when they are installed and it did happen.  Cleaning up was a lot easier with the water soluble yellow glue than it would have been with epoxy. 

 

 After letting the glue cure overnight I put the rifflers in the box and was done.

I had fun doing this project.  I know I could have used a canvas roll to store the rifflers in but I wanted a wood case.  I had the walnut on hand so the only thing I had to get was the brass.  Besides I am retired and just wanted to build this. :)

Rifflers Handles & Case - #5 Base Assembly & Top Part 1

With the spacers fitted and the ends sanded I could start doing some assembly.  First is to glue the spacer into the ends.  This is done in three steps.  First is to glue the interior dividers into one of the end blocks and clamp them in place.  This photo shows that step.  I only glue one end in at a time to reduce the number of glue joints I have to work with at a time.  The second step is to glue the other end on and the third is to glue the outside dividers on.  I left them until last just to reduce the number of joints and to reduce the complexity of clamping as these pieces needed to be clamped in two directions.

Once the glue cured I could use a full sheet of sandpaper clamped to a piece of granite to flattened the joints by rubbing the divider assembly back and forth on the sandpaper.  The joints were very close except for one but this allowed me to get everything completely flat prior to gluing the base on.

I also flattened the top of the assembly and by swapping out the sandpaper to finer grits I got to my finished surface.  In this closeup you can see how careful joint fitting makes everything go together nice and tight.

Next up is to glue the bottom on the divider assembly.  However, before doing that I checked the dividers themselves to make sure I had a finish sanded surface.  It is a lot easier to do it now versus when everything is all glued together.  Since the bottom had set for a few days and was just sanded to 100-grit I ran it through the thickness sander to make sure it was flat and get a 220-grit surface.  With that done I was ready to glue the bottom to the divider assembly.  I could have cut the bottom to fit the divider assembly then glue it on but decided to just get it close before gluing on then trim it to an exact fit.  It would be just my luck that the bottom would slip a little during the glue-up and that would cause me some major grief.  A flat base, a couple of cauls and eight clamps hold everything together while the glue cures.

With the glue cured I used the table saw to trim off the excess base getting close to ends and dividers.

To trim the base right to the ends and dividers I used the router table with a flush cutting trim bit installed.  The bit has a bearing that rides on the reference surface guiding the cutting edge so the finished cut is almost perfectly aligned with the end or divider.  The top photo shows the setup ready to cut and the bottom one shows the finished cut.  A little sanding to remove the cut marks and I am ready to move on.

The next piece that gets attached forms the pocket to hold the rifflers in place.

This piece is cut from the glued up top panel.  The remainder goes to make the pivoting cover assembly.  That cut is not a 90 degree cut but is at 30 degrees.  I set the angle using a digital angle measuring device, tape the cut to help reduce splintering, set the fence at the proper distance and make the cut.

Once cut, the smaller cut top piece gets glued to the already assembled parts.   Not to hard I just have to make sure the bottom edge of the bevel matches up with the end of the cutout.  If you look close you can see how much oversize the piece was cut.  Once the glue cured I trimmed the top piece to fit with the router as before.

Next is to sand the beveled edge on the larger top piece.  I did not show the edge sanding of the smaller top piece but the process is the same.  A guide block cut to the same 30-degree angle as the bevel piece and a sheet of sandpaper is clamped to the granite reference surface.  Pressing the piece to the guide block I move the piece back and forth until the edge is sanded. 

Setting the top piece aside for a bit I took the lid sides that have been sitting since post 3.  They were still flat and true so I ran them though the thickness sander loaded with 220 grit paper to smooth out the surface.  One end is trimmed for a square cut and then they are cut to length.  First cut is with a stop block just a little oversize.  Final fitting cuts are made by adding playing cards next to the stop.  I find playing cards to be just about one-hundredth of an inch thick.  In this case I need two cards.

Cutting the top to width is up next.  On each side between the lid and the base there will be a thin nylon washer about .03” thick.  Add a couple hundredths for play and I needed the top to be .05” wider per side or a total of .1” That translates into 5 playing cards per side taped into place.  In the photo below, you can see the cards along with a couple of maple spacers to assure that top will be in the same plane as the top piece on the right side. 

After some very careful trimming the lid fits between the sides and as the photo shows the grain runs interrupted along the top.  Last is to cut the top to length.

Gluing the top and side together are next.  This is the setup I used, the big orange clamps are clamped in my bench vice for stability.  The fewer parts I have that can move around on me the better.  I do a dry run to make sure things will go smoothly.  While everything is clamped I tape the side of the lid down to the orange clamp.  You can see the green tape on the right side.  Once again, the fewer moving parts I have when gluing pieces together the better.  I unclamp, add some glue then clamp everything back together.  The same process is done for adding the other side.

Next Up –Top Part 2 & Finishing