Thursday, 29 March 2012

Having Fun for a Good Cause

I spent last weekend at the Matisho Memorial benefit for cancer research.  This is a two day get-together for woodturners to turn, learn, and socialize.  The price of admission is a cheque made out to the Canadian Cancer Society.  The event is open to anyone who wants to attend and is not limited to turners.  Carvers have been coming for years.  A couple of girls demonstrated marbling last year and this year they were kept busy marbling all sorts of turnings.  This year also had people doing inlay, airbrushing, and even a blacksmith.

Encouraging new turners is also a big part of the weekend.  This year there must have been at least 20 kids from eight to fifteen that came in to try their hands at turning.  Last year a man came in with a beautiful chunk of spalted maple and asked if anyone could make a bowl for him.  Of course someone will, they said, and that someone is you.  He soon found himself in front of a lathe turning his first bowl.  He was back this year with his own lathe and brought his kids with him.

I would love to show you a lot of pictures of everything that went on this weekend but my camera simply would not co-operate.  It seemed every time I wanted to take a picture I had to take the batteries out and switch them around.  It made it almost impossible to catch any of the action, but here are a couple of shots I did get:

It's a pretty relaxed weekend and there is not any pressure to get anything done.  you can turn for a while, grab a coffee and a snack, wander around and watch or ask questions.  People come up and chat with you while you're turning and it's kind of like blogging except you know someone is listening.

I did manage, with several tries, to get a few shots of what I was working on.  When there are a lot of people around to ask for advice I like to try something new.  This time it was multi-axis turning.  I had a blank about 1-1/4" square by 12" long that would make a good stem for a candlestick.  I started by marking the centre at each end and then marked out eight more points along the diagonals as shown in the picture below:

The inner points are about 3/16" from the centre and the outer one about 1/2"

My plan was to make a crankshaft-sort-of-looking-kind-of-thing with larger and smaller diameters stacked up with various offsets.  I would always use the same offset in the same direction so the axis I was turning on would always be parallel to the original centre line.  I rounded off most of the blank leaving the ends square so the outer points would have more support.  Next I turned a tennon to attach the top off the candlestick.  Then I moved the blank to a set of the inner points and made a round section centred on that axis.

It became clear in a hurry that I was not going to be using the outer set of points.  I was really surprised how much smaller the diameter became with such a small change of centre.  Once my focus readjusted I changed the centres again and made another cut.

I proceeded, then backed up, and proceded again, working my way down the blank.

Once I had finished the stem I moved on to the base.  First I turned it round and then I offset it a bit and turned a short tenon on the bottom.  This is the best picture I was able to get.

You can see the second centre point and you can almost see the offset tenon.  I mounted the tenon in my chuck and turned a hole in the top side of the base that matched the bottom tenon of the stem.  After I had a snug fit I turned the rest of the base.

Believe it or not it took me all day to get that done. 

The next morning I started on the top of the candlestick.  Again I started by turning the blank round between centres but this time I turned the tenon on the same centreline.  Before I mounted it in the chuck I took it to the drill press and drilled a 1" offset hole in the tenon.  I then took it back to the lathe and turned another hole to match the tenon on top of the stem, then rounded off the shoulders.

Once this was done I changed my regular chuck jaws for pin  jaws and stuck them into the 1" hole.  I then made a cove cut on the inside of the blank to give me this result:

And here it is assembled:

I felt that a piece this wonky needed something special for a finish so I headed over to the marbling station.  I really don't know too much about the preparation of the marbling bath except it contains something calle 'alum'? which allows the acrylic paint to float on top of the water.  The paint is then added by whisk and stylus a drop at a time until you feel you have enough.  It is best to use at least three contrasting colors.  When you feel that you have enough paint you may or may not 'comb' the paint.  I did, and this is what the bath looked like just before I dipped:

And here are some shots of the finished candlestick:

I did get started on another multi axis turning but none of the pictures I took survived.  I'll finish it at a later date and post it then.

Sunday, 18 March 2012

If a Spiral Staircase and a Bookshelf Had a Baby...

This is what it woold look like.  Maybe.

I finally finished my 2 x 4 Challenge project.  And only a month too late. In case you're wondering, it's a plant stand.  It stands about 27 1/4" tall and the outside diameter is 10 3/4".

As I mentioned in an earlier post this is an idea that has been rolling around in the back of my head for a few years now.  The legs, of course, are the biggest problem.  They don't just bend, they also twist.  At first, I couldn't wrap my head around how to solve this problem.  Cutting the legs out of a flat board wasn't possible.  Machine the legs out of a solid log?  Too much work, too much waste, and too big a log to work with.  I knew it had to be done somehow because it would be just like a bannister on a spiral staircase... spiral staircase!  I asked someone who worked for a company that made bannisters.  "We laminate them" he said, and the light bulb finally went on.

I did a couple of small scale tests with veneer and while the idea seemed to work I could not get even clamping pressure all along the leg and that left the outer edge very uneven.  I shelved the idea for a couple more years.

Eventually I came up with the idea of using shrink wrap to even out the pressure.  It wasn't the perfect solution, but with multiple layers any difference in pressure would change gradually and would not leave a noticeable diference in thickness.  When the 2 x 4 challenge came up I decided that I had solved enough problems to give it a try in full size without wasting any expensive wood if it didn't work.

To start, I cut the 2 x 4 into two three foot and one two foot lengths.  I then ran them through the tablesaw on edge and ripped them in half.  This left me with six pieces that were just over 5/8ths by 3 1/2 inches.  I set the two footers and one three footer aside for the shelves and started to rip the other pieces for the legs.  This was done on the bandsaw to conserve as much wood as possible.  I would cut off a strip that was just under 1/8" and then joint the fresh edge on the remaining board with my #5 Stanley, trying to keep it square to the board.  Mixed results on that, I have to practise more in the future.  I could have used the jointer but even at a fine setting it takes way more wood off than the plane.  Besides, the jointer scares me.  As the board gets smaller and smaller my fingers get closer and closer to the blades and using push sticks doesn't reassure me.  That's another reason I want to learn to use hand tools.

After cutting each strip I would give it a bend/twist to see if it would survive when I clamped it to the form.  Being spruce, a lot of pieces did not survive due to knots and other defects.   My original intention was to make the legs two inches wide but when I got to 1 5/8" they looked "right" so I left it at that.  This meant that there were 14 strips per leg.  By keeping the legs narrower I also kept the shelves smaller which turned out to be critical in getting it all out of the same board.

With the strips cut I was ready to glue them up on the form.  I did a dry test run without glue first.  It was a total disaster.  I couldn't hold the form still when I wrapped the strips around it.  The strips popped out of the clamp or wouldn't stay aligned.  It was going to be almost impossible to hold the form while I shrink wrapped it.

Solving these problems required a two pronged approach.  The first was to mount the form vertically on a pedastal.  This allowed me to step on the base to keep it from turning when I wrapped the strips around and when I shrink wrapped it.  The second was to glue the legs in three steps of 5, 5, and 4 segments each.  Here is a picture of the glue up for the first segments:

And the second:

I glued the legs together with Cold Cure epoxy which has a very long open time.  It takes quite a while to glue, clamp, and wrap all three legs and I let all three glue ups cure for 2 days before taking the wrap off.

While the glue was curing it was time to work on the shelves.  Because the shelves change radius I cut three different lengths to conserve wood, and then cut them at 30 degrees with a jig.

I glued up each shelf in three sections, bandsawed each section close to the final shape, and used another jig to sand them to final size on the oscillating spindle sander.

Another jig held the shelves for gluing.

And then the centre was rounded out at the drill press.

I turned the centre disc on the lathe and glued it in place and smoothed eveything down with the random orbit sander.

Once the shelves were complete it was time to pull the legs off the form and smooth them down.  Clamping was a bit of a struggle, but for once my crappy work bench actually seemed to be an advantage.

I smoothed the legs with a spoke shave and card scrapers.  This is the first time that I have used a spoke shave and I was really pleased with the way it worked.  I just wish my old Stanley # 60 was a little wider so it could have done the whole width of the leg at once.  And I wish the handles were shorter so that they didn't hit the bench as I worked around the twist.

And I wish it was just the straight blade.  I guess building a spoke shave is in my future.  The sweetheart blades are nice though.

After a few hours of shaving, scraping, and sanding I was ready to fit the shelves to the legs.  This turned out to be more of a problem than I anticipated.  The legs, instead of following the radius of the form, all leaned in a little or a lot.  This was probably caused by poor alignment during the glue up and by the springback that happened after the legs were removed from the form.

To compensate I used a drafting compass to measure the gap at the inside and transfered the measurement to the outside of the shelf.  I then cut on a line from that point to the inside corner.  Once the leg was parallel to the shelf there was still a gap at the top side of the shelf.  I set the compass to the width of this gap and transfered it to the bottom side of the shelf.

Next I cut from the inside top corner down to this new line:

And then along the length of the line and the top edge so that I had a surface parallel to the surface of the leg (sort of).  Once all nine of these joints were cut I marked a quarter circle on the front and back of each leg that had a 1 3/8" radius that went from the top of the shelf  up the leg and then a horizontal line to the outside edge.  Then I cut outside the line with a coping saw and finished it with a rasp and sandpaper.  I had to go out on a Sunday and buy a coping saw to do this because I had never used a coping saw before.  I hated it.  That's what you get for $12.00.  Life really is too short for cheap tools.  The same thing applies to clamps.  This one darn near took my eye out when it let go.

T.G.F.S.G. (Thank God for safety glasses)  I repeated the last few steps at the bottom of the legs as well.

To fasten the legs to the shelves I decided to use dowels.  I made an alignment block to space the dowel holes properly on both the legs and shelves.

When I drilled the first inside hole at the bottom of the leg I discovered that there wasn't enough wood there for the hole the way the leg was cut.  Fortunately this is just a prototype and it is on the bottom where no one will see it.  Anyway, the bottom shelf only has one dowel per leg.

At last it was time to assemble the whole thing.  Keep in mind that up untilthis point I was still not 100% sure that this thing was going to work.  Again, I did a dry fit to try to spot any problems.  The first leg went on just fine.

The second was pretty good too.  The third was terrible.

How I managed to get this so out of whack I have no idea.  It's not just a bad joint either.  The dowels are out of alignment as well and when I tried to push them in a little further they split the laminations.

IT'S JUST A PROTOTYPE.  (repeat until you stop felling disgusted)  I glued it up anyway.  I did put a patch in that joint.  Actually, now, it's probably the best looking joint of the bunch, at least from above.  It really made me question my decision to angle all those joints though.

Now that it's done I do feel that, as a prototype, it was a success.  The idea worked, and the overall shape and dimension of the piece looks good to my eye.  Having said that, here is a list of things I will do differently next time:
  • Thinner strips in the legs.  Even with spruce there was too much fight in these laminations.  thinner strips would allow the shrink wrap to hold tighter which would make for a stronger glue joint.
  • Alignment pins on the bending form to keep thins straight.  I think that is obvious.  Now.
  • Make the smaller diameter of the shelves a little larger.  Then I could notch the legs to fit the shelf which would make a better fit and a stronger joint.
  • Dowel through the side of the leg into the side of the shelf.  This would give more room for the dowel and would be hidden with the legs notched to fit the shelf.
  • Don't use spruce!
  • Add some detail to the edges of the shelves.  The plain, square edges just scream cheap.
  • Add some color.  Contrasting wood strips in the legs with matching inlay in the shelves would dress it up a lot.
  • Build the shelves diferently.  Maybe just three pieces or less.
 Here is one more shot of the completed piece.  If you are in Saskatoon and would like to see it it is on display at the Sienna Gallery in the Centre Mall, along with pieces by othe members of the Saskatchewan Woodworkers Guild until April 21st.