Replies

1. 
   mitch | Aug 15, 2002 12:36am | #1

   i love problems like this but i'm having trouble coming up with a suitable solution for making just one.  all my ideas so far would require so much set-up and fixturing you'd have to cut a hundred to be worth it.

   let me see if have your dilemma/design straight in my head-  from your piece of stock you want to end up with a piece that has a rectangular cross-section of .75"x 1.5" at any given point along its length, and completes a 90 degree twist (so that the ends are perpendicular to each other if you sight down the length from one end) about its center axis over a distance of 42"?

   if you don't mind some lathe and hand work, too, i'd turn the stock down to a 1.75" diameter cylinder (actual hypotenuse dimension of your rectangle is 1.677"), layout your cross-section rectangles on both ends at 90 deg. to each other, then connect the corresponding corners with a fine string or wire and carefully trace the curves (hold the string ends in knife cuts).  you might even try using a chalkline or sumi inkline since the curves are so long and don't travel far around the side of the cylinder.  then with the cylinder resting in two pair of v-blocks (one pr ahead of the blade, the other pr past it) clamped to your bandsaw table (you'll need to align and mount the v-blocks on a separate board) at the right distance off-center from the blade, turn the cylinder as you make your cut so that the blade continues to enter and exit the side of the cylinder just outside of your marked lines.  (maybe have somebody watch from the side?) i'd make sure to cut it a little oversize then even it out and fair the curve with a block plane and scrapers.  you should be able cut one long side and one, or maybe even both, short sides before you no longer have a good cylindrical surface to ride the v-blocks.  then using a point fence (just a vertical corner or curved fast-trak type, like some people use for resawing) set a little over .75" away from the side of the blade, cut off the last round side keeping the flat side firmly against the fence.  i'd recommend standing outboard of the saw with your left hand feeding the stock in and your right hand pulling it out, with both hands keeping even pressure against the fence as it turns, making sure to keep the stock axis running parallel with the blade.  once again, watching to make certain the blade is entering and exiting just outside the lines you're trying to connect.

   oh yeah, make one for practice first, as obviously i've never actually tried this!  good luck and let me know how it goes.

   mitch

2. 
   Andrew | Aug 15, 2002 06:46am | #2

   Gene, does it have to be bandsawn? I think it would be alot easier to just carve it, or even easier still would be to make a simple jig so that you could steam bend it and twist it to shape. just make sure to over twist it to allow for some springback. hope this helps

   andrew

3. 
   PlaneWood | Aug 15, 2002 05:05pm | #3

   Haven't tried this - just a thought.

   Could you mark a line on top of the 2x2 block starting 3/4" to the left of the right side on the leading end and to the left corner at the trailing end?  Then, clamp a thin stop onto the table that is 3/4" to the right of the blade.  As you pull the block through the blade, keep the bottom right corner engaged with the stop while tilting the top to keep the blade following the line on the top of the block.  That would get the first side.  Might practice on scrap first.

   PlaneWood by Mike_in_Katy
   PlaneWood

1. 
   mitch | Aug 16, 2002 03:44pm | #4

   i thought about steam twisting but looked through several articles and fw's book on bending wood and couldn't find any mention of it.  i was kinda surprised- it can't be that different as far as the wood stresses are concerned.  also, maple is not usually found on anyone's list of favorite woods for steam bending.  give it a shot- if it works it should be a heck of a lot easier than my aforementioned suggestion.

   mitch

1. 
   Boxduh | Aug 20, 2002 05:30am | #5

   I should have asked the guy who began all this, the buddy who made my table benches.  Each has a tiger maple stretcher that executes a 90 degree twist from one end to the other, and a cross section about 3/4" x 1-1/2".  I suspected some sort of jig, but as it turns out, he freehanded the blanks, square sections about 1-3/4" square, through the bandsaw, going in from each end toward the middle, where he knew he had to end up 45 degrees from where he began at either end.  Lots of work at the inflatable drum on the sanding machine thereafter.  They are really neat to see in the highly figured and well finished tiger maple, with the quartersawn grain figure moving from one edge to the adjacent edge in a gradual transition from end to end. 

4. 
   CoastalCarver | Aug 21, 2002 01:25am | #6

   Guys!  Think hand tools and it will be much easier.  First mark out what you want to do.  Get out a good bow saw.  Saw it out staying shy of the line and use a spokeshave to clean it up. 

   Lots of times it's easier to do it with hand tools, especially on one off stuff.  When you think only in terms of power tools you are really limiting what you can do.

   Brandon