“Offering”

[Mark J]

I am going to try my hand at another journal.   I took a lot of photos as I went along on this project so I thought I'd post them in manageable groups. If you do want to quote this post, in the interest of space, please be selective about the specific sections you want to repeat.  

This is going to be another convolved form similar to others I have posted about on this forum.  The idea for this project started with a comment Chestnut made with the last piece I wrote about.   He said, “I know you like your pieces to hint at the ability to serve a use but I'd be interested in what you came up with if you threw function out the window and just went for showy”.  That got me thinking, what if I left out the bowl entirely and just kept the rest of the convolved form (that’s what I’ve started calling these pieces).  That left a ring on the bottom and one on the top.  In and of itself I wasn’t too keen on the shape, but that then got me thinking about a design I had sketched last fall, but then abandoned.  You can see that design on the left most sheet in the picture below.

I had envisioned that design to be contained within a single block of wood and suffice it to say I couldn’t see how to do it.  But now the thought came to me to make it out of two pieces of wood.  The base would then be a convolved form with no bowl (and ultimately no top ring, either).  The basin could then be much bigger.  In the picture above you can see several of the sketches I went through, before settling on the design below.  

Typically I like to have 90 and 45 degree en face views as well and while it is possible to draw these in 2D it’s nice to have a 3D drawing to work with, particularly as it gives you an opportunity to see if all this work is going to amount to ugly.  So I embarked on trying to learn just enough of Fusion 360 to get some pictures.

Here are drawings of the base as it will be turned and before sculpting the pillars.  

And here are the base and basin together.  

The drawings of the base in this after sculpting depiction are crude.  I am not talented enough with Fusion 360 to draw what I was thinking accurately, so this is just a gross representation.  But, now armed with my diagrams, 3D drawings I started to work on real wood.

So first step is to cut off an appropriate piece from my stock.  For this project I chose to use dry Honduran mahogany that I had acquired a year or two ago for the base, and an 11 by 5 inch round of dry curly maple I had for the basin.  I’ve talked about this before, but the convolved forms require starting out with a truly squared turning block, otherwise the pillars will not be equal in size.  I’ll mostly let the pictures speak for themselves.  The key point in squaring the block is that 2nd and 4th sides are in the longest length of the block, and that when setting up for the 3rd cut you have firmly fixed a stop so that the third and fourth cuts are exactly the same length.  Also, I used the marking gauge on the third cut for this particular piece as I wanted the block to be a specific dimension.  

Once square on four sides I need to square and flatten the faces.  Instead of a router sled the block is sled mounted and the router is in the table.  

The partially smoothed surface.

Once the first face is smooth flip the block and smooth the second.  

The block is square and flat on 6 surfaces.

Mark up the surfaces with all of the information that may be needed for turning and to drill guide holes for depth and the guide pins.  

The top.

The bottom.  The sides of this piece are to be cut back so bandsaw cut lines are also drawn in.  

And mark the sides for the guide pins.

Holes for the guides and for the screw chuck are all started as accurately as possible using the drill point countersink bit with 1/8” drill point, 5/16” final diameter and 60 degree cone.  The DPCB is then swapped out for the appropriate bit for each hole and the hole drilled to an accurate depth.

Here a 1/8” bit follows the DPCB to drill a hole for one of the guide pins.  

The top receives a 5/16” hole for the screw chuck, the bottom gets a Forstner as a head start on hollowing.

Well that's enough for this first installment.  Next will be the bandsaw work and turning work on the base.  I hope I am not including too much or too little detail.

 

[treeslayer]

Always like your journals Mark, pushing the limits on what can be done with wood is an inspiration for the rest of us mere mortals and I always learn lots of new things, looking forward to this one for sure

[Bmac]

Interested in following this, I'm not really sure how you are getting there but I'm in!

[Chestnut]

AWE I"M SO EXCITED!!!!

[JohnG]

Definitely following this! I’m going to have to read this again when I’m fresh so I can take it all in. 
 

I like the router sled thing. Very neat idea. 

[fcschoenthal]

Not that I would ever be able to do something like this, but I'm following as well.

Love to see the process to create something like this and am definitely stealing some of the jig ideas.

[Mark J]

Second installment.

The sides of this piece are cut back, which narrows the corners and gives a longer and narrower space in which to form the pillars.  This allows the pillars to be a little more dramatic.  However I actually made a “mistake” in sequencing the steps on this project by removing that waste wood now rather than after the pillars were mostly formed.  To explain briefly, whenever I turn one of these convolved forms I encounter end grain chip out from the trailing edges of two of the pillars.  This occurs where the grain runs perpendicular to the tool path and the pillar is getting thin, in other words just as your approaching that final contour and you really don’t want chip out to happen.  Since this frayed trailing edge would be within the waste wood, if you wait on the bandsawing you get to cut off the chip out.  Well mostly, you still have to be careful, but you do get that extra insurance.  

In order to trim the waste wood at a later stage I would have needed to make a simple jig, rather than what I did below.  I admit a little get done-itis thinking may have influenced my decision making.  All in all this project has gone on for about 3 months, with a few false starts, so at this point I wanted to get rolling and not stop to make a jig.  

So I just used the miter gauge from the table saw being careful not to cut farther than the exact line dimensions.  So here’s a trick on that point.  Just because your machine has a motor does not mean that you have to switch it on.  So with the power switch safety engaged I turn the drive wheel by hand and just eased up on the apex so as to not overshoot.  I was a little off of the line on some of my cuts, but that accuracy was within tolerance given the sculpting to come.  

The next step is to transfer the 90 degree en face view to each of the four sides.  This drawing was adjusted slightly to reflect the fact that the 90 degree view was being projected onto a non flat surface.  This is probably not strictly necessary, after all you can only get so accurate with carbon paper transfer, but my MO is to be as exact as I can and it was actually not difficult to make the adjustment.  There will be enough inaccuracies later; I don’t need to make it worse now.  

The piece is now mounted on the screw chuck.  I want to remove some of the bulk material so I have drawn lines showing various depths I can go and for each depth I mark a diameter measuring from the corner inward.  Having removed the bulk I have an odd wedding cake form.  

The drawings made on the outside of the form serve as a guide to the final contour.  The actual shape will be determined by eye, but may be surprisingly close.  After completing the outside of the base the red guide pins can be glued in place.  Then I can move on to create a mortise in the bottom.  I use the diamond tool to create a dovetail on the inside wall to match the dovetail on the chuck jaws.  

With the mortise done I can begin hollowing out the base, entering through the middle of the mortise.  The Forstner hole is a head start on this tedious task.   Notice how the guide pins are helpful for lining up the hollowing tool.  The guide pins can be seen well while the wood is spinning, but it pays to stop periodically to peer inside and evaluate your progress.  The guide holes are empty while the ends of the guide pins can be seen.  

Clearing out the inside is tedious even with the Forstner hole, but eventually the tool makes it to the outside.   Since the sides were already cut back this point comes a little sooner—so there’s that.  Notice that my trajectory has taken me closer to the lower pin than the upper.  I’m still in the path, but I’ve lost the lower pin.  The upper is still an adequate guide, especially because I can now see what I’m doing directly through the opening in the side of the form.  

Closing in on the upper pin, while following the guide holes to form the inner contours. 

You can see the end grain chip out on the left hand margin of the opening in this photo.  It is getting uncomfortably close to the expected final contour.  

So time to chamfer the edge which I do with a Dremel and small sanding drum.  This process has to be repeated periodically as the chamfer is cut away by further turning of the inside.  

Work at it long enough and you get something that’s starting to look like something.  

If I had not yet cut back the sides this would be the time for that operation.  The problem as you might already see is that there are no longer any corners to line up with the saw blade, and the cut lines are also probably gone.  The trick is to have a template already made with a screw and hole ready to attach the bowl just where the screw chuck was.  This re-centers the bowl, but you do have to rotate the bowl to get the alignment just right.  With a little thought and planning this works well and it’s what I did on the last project.  

So time to sand the outside and inside surfaces.  At this stage I will leave the area of the mortise alone as this will be removed at a later step.  For the remainder I start anywhere from P60 to P120 grit depending on the condition of the surface and how much tweaking the contour needs.  It is possible to focus the coarse grits on an isolated rough patch so that you don’t have do all of the surfaces with all the grits.  I also found the H. mahogany to be remarkably responsive to the sandpaper.  At one point I accidentally went from 80 to 180 grit and actually had no problem.  Typically at this stage I will not skip grits and work my way to P320.   It will ultimately get sanded finer, but this is good for now.  

With the initial sanding completed I flip the piece, mounting the mortise to the chuck, then shape the top.  Since there is no bowl this was pretty quick.  The astute eye will notice that a crack has formed at the mortise ring.  This ring was just too narrow for the mahogany.  There were actually two cracks.  And I got lucky.  Very Lucky.  I was able to complete the turning then dribble some thin CA in the cracks and release the chuck closing the cracks on the adhesive. That's why there is brown paper on the lathe bedways.   It worked.  I did drip a bit of CA on the chuck, but was able to easily remove this with acetone.  By the way it's best to apply acetone with a brush or cotton swab, it readily goes through nitrile gloves.  

The base is now largely formed.  At this stage it looks just like the 3D drawing.  The next steps will be to turn off the mortise ring and then cut apart the top ring and sculpt the pillars.  I will leave it as is for now as I will need to use the top ring to size the basin’s bottom, and there is a remote chance I will have to test my luck and turn the top ring further if it is not wide enough to allow a beautiful basin.  But next is the basin.  

 

[Bmac]

Ahhhhh! I see, I think I understand now, just don't ask me to do that!

[Coop]

One, I don’t understand it, two, I could never dream that up and three, there’s no way I’d ever attempt it. But You’ve done all three and looks darn good so far! 

[Mark J]

So this bowl is going to need a basin.  I had available an 11” round of dry curly maple measuring about 19/4 in thickness which was just perfect for the design.  I scored this piece about a year ago and wish I could find some more, but really thick dry wood is hard to come by.  

First step is to consult the drawings then mark up the blank for drilling and turning.  On the diagram you can see the guide holes are drawn in life size.  I shoot for guide holes that are about ¼” short of the final contour.  I want to get into the vicinity, but still have some wiggle room.  After markup, drilling.

The big block is then mounted for turning.  I think a blank this big is too much for a screw chuck and prefer a tenon and a big one at that.  Still you gotta hold the blank to make the tenon.  Here I have the 130mm chuck jaws closed and pressed firmly and flat against the blank by the tail stock.  The cone center on the tail stock is nicely engaged in a ¼” deep conical hole I’ve made with the drill point countersink bit.  It is the friction of the chuck jaws against the wood that rotates the blank.  This is a pretty secure temporary mounting, but there's no reason to dial up the RPM into the “do I feel lucky” range.  

I create the tenon by digging a “moat”.  This allows me to preserve the outer material which is often part of the rim or may be marked up with indicator lines I’ll need later.   As in the earlier section I’ll use the diamond tool if I need to bevel the tenon for dovetail jaws.  

Once the tenon is made I can flip the blank and mount the tenon in the chuck.  By the way if it wasn’t clear before, the tenon is on the top of the basin.  Next is to begin forming the bottom curve of the basin.  Although my preference is often for carbide scraping tools there is a great deal of material to remove from the bottom and I found that bowl  gouges were the most efficient at taking down this bulk.  This also gave me an opportunity to practice with tools with which I am less familiar.  

Eventually the bottom gets too narrow for the tailstock, but fortunately the mass is also reduced.  Once the tail stock was removed I stopped frequently to compare the developing curve with the opening in the top of the base component.  The goal is for the tip to extend far into the base, but not too far, and this is a function of the narrowness of the curved cone and the diameter of the opening in the base.  

As much as I was enjoying practice with the bowl gouge there wasn't enough clearance to swing the tool through a wide enough arc to close in on the final contour line, so this was achieved largely with various scrapers, including an HSS round nose negative rake that I recently purchased.  

Once formed the basin bottom was then thoroughly sanded achieving a cami 1000 grit finish.  With that side complete it was on to forming the hollow and work holding starts to get a little more tricky.  The first wood is removed from the hollow by just accessing from the headstock side,  removing as much as practical.  

In fairly short order access to the hollow becomes constricted due to the size of the 130mm jaws.  So in order to change the mount to smaller jaws the chuck is dismounted from the spindle with the blank still in the jaws.  The live center is then placed into the tailstock and a spindle adapter inserted into that.  The chuck with blank is then screwed on to the spindle adapter.  This preserves the alignment and centering of the blank.  The suck chuck—OK, it’s a family forum—the vacuum chuck is then installed on the headstock spindle and the blank is then positioned into the vacuum chuck and vacuum applied.  The chuck jaws can now be released and the chuck withdrawn.  

Remove the chuck, replace the cone center and behold I bring you tidings of great alignment—the cone fits exactly back into the conical recess made earlier. 

 

So one could just start removing wood and forming the hollow while leaving say a one inch diameter column of supporting wood extending from the cone center to the bottom surface of the basin.  But there’s a but.  The 4 inch diameter vacuum chuck prevents one from getting fingers or calipers onto the basin wall in the central half, so there is no way to be certain of the thickness or uniformity of the wall as you remove material.  Now Theory says you can release the vacuum, check the wall and then return the piece to the vacuum chuck using the cone center’s dimple and the self centering nature of the conical shape of the basin to achieve alignment.  But Theory is not a woodturner, and that is never going to work, largely because the curved cone is not that self centering and the vacuum chuck will seal with the basin significantly askew.  Which will in turn lead to lamentations of Biblical proportions. 

Instead I made a new tenon sized for 50mm jaws, then with the blank still in the vacuum chuck carefully switched the cone center for the chuck and jaws.  The vacuum is released and the chuck is returned to the headstock.  
 

With the headstock rotated behind the ways I have fairly good access to the basin top. The 50 mm jaws allow further access, and I was able to continue forming the hollow while still monitoring the wall thickness.  I used a variety of tools, but the star of this part of the show was the diamond detail carbide scraper.  This is the only tool I have that is both narrow enough and thin enough to get into this space.  

Eventually even the 50mm jaws were restricting access and had to go.  So using the same process as before the blank and chuck were mounted to the tail stock and the blank then transferred to the vacuum chuck.  The cone center was engaged and again thankfully lined up with the dimple.  Forming of the basin hollow could then resume.  

Again I got to a point where there was no further room to work without removing the support column.  Prior to cutting this back I took a chance and removed the basin to evaluate the wall thickness.  Fortunately at this point I am close enough to the center of the bottom that the risk/consequence of misalignment is minimal.

With the basin re-mounted I begin to whittle away the support column until I cut through.  In the center you can see one more guide hole indicating the depth of material remaining to be removed.  

The basin hollow is now shaped.  Sanding again through the grits up to cami 1000 and the basin can be set aside in a safe place pending completion of the base which will be the next adventure. 

 

[Chestnut]

I'm gonna stick to furniture.....

[Bmac]

50 minutes ago, Chestnut said:

I'm gonna stick to furniture.....

 

Come on Nut, you got a lathe now, lets see some stuff.

 

Awesome stuff Mark!!

[Chestnut]

2 hours ago, Bmac said:

Come on Nut, you got a lathe now, lets see some stuff.

I'm going to post my incredibly mediocre ice cream paddle i turned in this thread just to bring it somewhat back to reality.

This is pushing my skill level.

 

[Mark J]

20 minutes ago, Chestnut said:

incredibly mediocre ice cream paddle

What are you talking about?  That's a segmented piece! 

[SawDustB]

11 hours ago, Bmac said:

Come on Nut, you got a lathe now, lets see some stuff.

I think we can mark this moment when @Chestnut saw his amazing productivity in the workshop plunge to zero...

Looks amazing so far, Mark!

[Mark J]

I return now to completing the base.  As it stands the base still retains the “disappearing mortise ring” and this needs to be removed with final shaping of the lower third of the inside of the base.  The whole base then needs more sanding to bring it to a P600 finish.  So the first step is to mount the base onto the Longworth chuck then capture with the donut attachment. 

With the base secured the bulk of the material can be removed, then the donut removed and the final contour achieved.  Then sanding of the entire piece to P600. 

The next stage is to remove the unwanted portions of the top ring and sculpt the pillars.  I marked out the location and approximate form I expected the pillars to take as they rose up and curved inward.  Then I drew some pencil lines giving the tape a wide margin to to show what I could safely waste.  

I planned to use the bandsaw to cut these lines, but it was difficult to be sure where the kerf would occur with the complex curve of this surface.  So I hit upon this idea.  Using a strong light with a single LED source and positioning the base carefully using wedges I was able to line up a very sharply defined shadow from the bandsaw blade showing me where the cut would occur.  

This was surprisingly effective, and I repeated the test for all three permutations of the cut.

These circumstances are unusual, but keep this trick in your pocket should you ever be in a similar situation.  However, after studying the bandsaw options and consulting all ten fingers I decided to use a hand saw and simply saw through one side of the ring at a time.  Cutting two side of the ring at once just didn’t offer any real benefit. 

I then repositioned the masking tape to more carefully mark out the intended shape for the pillar, and here I ran into a small problem.  

When I had originally conceived the piece I had just planned to have the pillars taper more or less continuously from the wider lower segment up and around to the inside.  However, I was not able to drawn this design in Fusion 360.  I was only able to make a crude representation, which at the time looked crude, but I believed would look good when I could see it for real.  It didn’t.  It looked crude.  In a butt ugly sort of way.   So I began sketching out different ideas and must have gone through at least eight renditions.  

Unfortunately at this point I had already cut away the top ring on the assumption that the pillars would have a simple taper.  Fortunately I had left that wiggle room.  After several trials I settled on my design and cut this out of post-it note material, the kind with adhesive all over.  Then I traced the design onto all of the pillars.  

It was very important to get the tips exactly centered.  So I stretched a rubber band around the base getting this on the high point of the curvature of the pillar, then sighting down with both top and bottom of the rubber band aligned I was able to mark the centers for the tips.  

Cole jaws (with the lathe switched off) make for a poor man’s carving vice.  I like to use a small sanding drum on the Dremel to shape the edges of the pillars.  Eventually I’ll have a Foredom or Mastercarver, but in the meantime I have bought a flexible shaft attachment for the Dremel and this has been a big help.   

Diamond rifflers and triangle file are also part of my standard kit when a bit of sculpting is needed.  These are followed with sandpaper, again to P600.

The base is nearly completed.  Notice that the side of the pillar is not simply a flat surface, but that this plane twists as it rises from the cusp of the V to the pillar’s inwardly bent tip.  I feel this small detail adds quite a bit grace and curve to the pillar.  

The last detail before surface coating is the brand.  Using the flat tool rest to reference the heated iron I put my mark on the bottom edge of the base, which by design is just big enough.   

Applying the surface coating is the last step, and more than the usual challenge.  Neither the basin nor base really has a distinct and well defined top and bottom, hence there is no place to break off with the varnish application.  So the entire piece has to be coated at once begging two questions, how do you hold it, and how do you put it down.   

I use Bartley Gel Varnish which is very viscous (more so than the General Finishes product).  It applies easily and quickly with rags; wipe on, wipe off, and buff after which it has very low tack.  

 

So I applied the varnish with one hand while holding the piece in my other hand using a large rag.  Then I used this large rag for a light two handed second buffing before putting the piece down to cure on a newly procured non stick baking sheet.  The baking sheet worked great.  And yes tested with a drop of finish and the cured finish does not stick.  

And that’s the end of this project.  Finale pictures of the completed piece just need a little tweaking, but will be posted shortly.

 

[Ronn W]

Beautiful,  just freakin' beautiful.  I like it.

[Bmac]

Really enjoyed walking through that process with you. Thanks for showing so many pics and giving such a good dialogue. Can't wait to see the final pics!

[wtnhighlander]

That is an impressive example of visualization! Even after seeing your initial drawings, I could not imagine how to create that on the lathe. Beautiful design, and amazing execution!

[Mark J]

Here are some pictures of the final result.  I call this piece "Offering".  

 

 

[Chestnut]

Wow that is incredibly beautiful. Each part is impressive but they way you get them to come together so perfectly makes the completed piece amazing. I could stare at this for a while.

[Mark J]

Thank you everyone, I really appreciate your kind remarks.  It's very encouraging.  

2 hours ago, Bmac said:

Really enjoyed walking through that process with you. Thanks for showing so many pics and giving such a good dialogue....

Thank you folks for following.  I was worried this would be too long and too much detail.

1 hour ago, wtnhighlander said:

... Even after seeing your initial drawings, I could not imagine how to create that on the lathe....

We had that in common.  There were lots of "well now how in the heck am I going to get from here to there" momments.  I usually sleep on a problem like that which might explain why this took so many months.  

[Woodenskye]

WOW!  Mic drop

[pkinneb]

Not gonna lie my head still hurts trying to figure out how you did that LOL

Beautiful!

[treeslayer]

Yep, mind blown, it’s something people should enjoy in a fine art gallery, an example of what fine wood art looks like made by a master at his craft!