Thursday, May 29, 2014

A Square Deal (8)

If you are new to this blog and/or post series, you may wish to start at the beginning of this thread:

A Square Deal

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For the past few weeks I've been doing nothing on this project other than monitoring the slab top for movement. What I've found over the weeks are two things:
  1. The top will move, and left alone it tends to want to bow up slightly in the middle
  2. The top is easily pushed back into straightness and held there - it can be kept in a stable position without trouble
I have the slab sitting on a couple of pine timbers atop a tablesaw:


I have straightedge on top so you can see how flat it is.

Another view:


After a few episodes of the top moving slightly and then finding I could get it back to flatness again almost immediately and without great force, I have concluded that my theory of using relief grooves on the bark side of the slab to 'break the back' of the slab's ability to cup has been borne out. Though the slab is 1.5" thick, it only has the strength of a 0.75" thick slab, or close to that.

I am quite confident at this point that the table frame, which connects to the top in eight places, will be more than adequate to hold the panel flat. Plus, when I cut the ends of the slab to mount breadboards ends, not only will the removal of wood make the slab weaker yet but the breadboard ends will add further stiffening.

I feel sufficiently confident that I have started resawing the remainder of the table components from the 'spare' 40" slab. It was in a holding pattern in case the tabletop misbehaved, and now can be brought into the process.

The slab is flatsawn in the middle, moving to rift sawn out to the edges. I sliced out the legs, stretcher, and apron pieces for the coffee table in short order. These were then jointed and planed, generously oversize, and I'll let then sit for several days to move if they are so inclined before another round of jointing and planing.

Next I needed material for the side table. Problem was though that the grain in the slab was starting to get slightly too flat for convenient cut out. So, wanting the end grain in the legs to run on a 45˚ rift line, I laid out for angled rip cuts:


The other side of the slab required greater angling:


My 14" Makita saw had a nice 50-tooth blade for ripping, however that blade ran into some metal last week while reclaiming gate material and was toast, so I had no choice but to use a 120-tooth blade for this work. Not at all a good choice for ripping, and a bit of a grunt, but it got me through, albeit with a couple of circuit-breaker trip outs along the way:


I have a new 50-tooth blade on order from Japan, but it will be a few weeks for that, so I make do the best I can. The slab was too heavy to consider lifting up onto the bandsaw and hand ripsawing - well, it never crossed my mind!





Next, over to the jointer:



After jointing I had a square arris to work from:


More re-sawing followed:



After that. a run through the planer produced the leg blanks with the desired grain orientation, at this stage about 3/16" fat:


 And then back to more circular saw work to obtain the aprons for the side table:


Next were the stretchers:


The pile of rough-cut stock gradually accumulates:


The two sticks on the left of the picture are cut from some other bubinga stock I had which was vertical grain and not curly. I thought that having crosswise breadboard ends with the same curly material as the table top slab would perhaps be a little too discordant visually, and the choice I made was to use some quieter stock for those two pieces:


The table design has been slightly revised as well. I move away from the asymmetrical breadboard ends with double hammerhead  key on one end, to having the keys on all four corners. This allows me to split the total movement of the top up between both sides instead of all at one side as previous.

The current design:


I've added an extra peg at the corners to stiffen up the mechanism a bit:


A couple of other developments have occurred as well. I've designed some custom router bits for making the hammerhead joints, and these bits, in three sizes, are being fabricated by Ridge Tool. For cutting the breadboard end joinery, I've decided to bump up the accuracy target a bit and am having a metal guiding jig fabricated. That should be ready next week, all being well.

All for now - thanks for dropping by the Carpentry Way. On to post 9.

4 comments:

  1. Chris,
    Most ingenious guard on your jointer.
    Is it stock, if so who is the manufacturer?
    Do you like it?
    Regards, Skip

    ReplyDelete
    Replies
    1. Skip,

      thanks for the question. The guard is stock for North American-spec. Martin jointers, but Martin doesn't make it. The company that makes it is in Germany, but I forget the name. The same company makes the BowmouldMaster that Martin supplies for their shapers (similar but not the same as the Aigner Bowmouldmaster).

      Here's a link to a webshop in Germany selling that style of guard:

      http://www.vemashop.com/epages/61278019.sf/de_DE/?ObjectPath=/Shops/61278019/Products/V00166

      ~C

      Delete
  2. CHRIS;
    Nice to see some sticks being cut.Can't wait to see more!Still looking good.
    J.T.














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