Tuesday, May 10, 2011

Coffee Anyone? (4)

Work has been progressing steadily on the coffee table the past week, while I have been wrestling with those various delightful machinery issues. Previous episodes in this thread can be located in the 'blog archive' to the right side of the page.

After allowing the glue to dry adequately on the table shelf panel, I cut the panel to its stretched octagonal form and rebated the edge:


Another view - can you spot the glue line?:


I have left the tongue on the edge a little fat for the time being, and only 3/16" in from the edge. Eventually it will be 1/4" in from the edge. I will plane the top and finish it before tackling that remaining cutting work.

I decided to build the shelf frame next. First of course the stock was re-sawn, jointed, and planed, then re-jointed and re-planed a few days later after letting the wood work out any residual stresses, taking the stock down to finish dimension plus 0.005~0.007" or so.

Then I did a bunch of layout, and forgot my camera that day so no pics sorry! I made a few different jigs to allow me to process a fair bit of the joinery work using a sliding table saw. Here's where things stood after the stock had been trimmed to length, and a rebate taken on one end:


Here's one of those jigs in the early stages of fabrication:


This above unit was to trim cuts at both a 22.5˚ angle and a 45˚ angle.

Following the large rebate, which defines a portion of the joint, I did a couple of cuts to define a tongue on the end of that portion:


Another view:


Then I decked that rebated surface down to dimension. I chose to use my router table for that step, placing a 3/4" MDF piece across to even out any potential issues from the slightly uneven top:



The cut depth was calibrated carefully, then I proceeded with the trimming:


Here is the result, the joinery surfaces nicely cleaned up on both the lap surface and the tongue:


A little closer look:



At the end of the day I made a start on the 'female' end of the joint - here's a spot in the process where I remembered to snap a picture, a section where I am just part way through that phase of cut out:



Today's cut out all went very smoothly and I am holding to a cut tolerance of about +/- 0.002" or so, right across the, uh, board, so to speak. I put that down to accurate jointing, which was made possible by having the jointer tables reground recently.

I should have the joinery completed in the next couple of days on these frame miters. Then I need to make the middle dovetailed batten and mortise the long frame sides and the shelf panel for that batten, then groove the inside of the frames for the Wenge panel, and finally mold the outside edge of the frame. Today I ordered up some custom-made knives for the shaper so I can produce the exact molding profile I want. Those should arrive by the beginning of next week I imagine.

I've made a few slight design revisions in the past week. The leg to frame joints, and the table top frame corner joints have been reconfigured. More on that when I get to it in the thread.

I have also put a 'pod' or foot back under the leg. Hello again! I kept feeling like something was missing there after I removed it previously, and I came to realize that it would be nice to have levelers anyhow on the bottom of the legs, so I decided that I could combine the earlier idea of a pad with a leveler. Here's a few of the ideas that I came up with:



In the end I liked the round button-like leveler foot pad on the left side of the above set. It took me a while to move away from polygons - a mental rut or something like that. The 'button' is petite and discrete, yet does just enough to bring the stirrup on the bottom of the foot a little more clearly up off the surface. The client likes it too, which is the main thing.

Here's a view of the table with the new legs and levelers:



And one more for good luck:


The profile on the shelf in the above pictures has been changed slightly in the last couple of days - making the bead a little smaller and recessed back in slightly. It should come out quite well.

All for today - thanks for dropping by the Carpentry Way.  ➪ on to post 5

12 comments:

  1. Chris

    Any chance of inverting the phenolic top to counter the sag? How about Jessem sending a new one, 'free gratis' as my uncle used to say? Or would the Lee Valley steel router table be a workable alternative?

    Hope to see your coffee table in Kramer's book!

    Tom

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  2. Tom,

    good to hear from you. Inverting the top? Well, no, it can't be done. Not be me at least. The router lift is incorporated into the underside of the top in a manner that makes it hard to alter. and I imagine even if I could invert it, it would eventually sag the other way.

    Jessem sending me a new top? Hah! Well I guess they would need to respond to my attempts to contact them so far, which they have not. It would be more than a new top though. They've changed the design so that the router lift now has a 8" x 11" (roughly) plate attached to it, which sits into a matching opening in the top. So, they would need to replace both the top and give me a new router lift to go with it. Put it this way, I'm not holding my breath. If they contacted me and offered me a deal on a replacement set up, that would be at least decent of them. They are preferring, it would appear, to try and ignore me. I imagine I'm not the only one complaining about this issue.

    I haven't given any consideration to the Lee Valley steel plate router top, but thanks for reminding me. I will consider it. Maybe I could obtain a 1/2" thick plate of plate steel and get it machined to accept the router lift I already have?

    Cheers,

    Chris

    ReplyDelete
  3. Hi Chris -

    You have probably posted this in the past, but what design software are you using ... the renderings look great. I can see where this could be a great aid in 'closing the sale' with potential clients.

    Regards,
    matt

    ReplyDelete
  4. Chris

    I kind of like the idea of 1/2-in. steel plate. Only the top would need machining, shims could deal with any unevenness on the bottom. A pivoting fence is easily made and adjusts very nicely. A drill and a tap would allow hold-downs anywhere. Since gravity works all day every day, it would probably sag over a period of 10 or 12 thousand years, but nothing is perfect!

    Tom

    ReplyDelete
  5. Matt,

    it's Google SketchUp, a free download, and yes, I think it is a great tool for communicating with clients. I also find it quite helpful to have the 3D when working on difficult 2D descriptive geometry problems. An, the 3D makes it easier to clearly see how parts intersect with one another and make minor changes that probably wouldn't have been thought of otherwise. The joint for this table shelf frame benefited in that regard.

    Tom,

    of course, the question is, how much would that cost? A simple hunk of steel - why not make it 3/4" thick? - but getting it cut to size, getting an opening milled in the top for the router, a t-slot machined in, then drilled and tapped. I can see that not being cheap at machine shop rates. Still, an interesting idea -- I wonder if cast iron has some inherent advantages that leads to its greater use over plate steel? The easier machinability of the cast would be one factor for sure. These day, CNC water jet cutters would make some of those cutting operations more straightforward.

    ~Chris

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  6. Vibration dampening is apparently better with cast iron than steel. Also, I just looked into the price of 3/4" steel plate of a size sufficient to replace the Jessem top, and with freight included, the raw material would be $700. I can imagine the machining could easily push the cost into the $1500 zone or higher. Hmmm...

    ~Chris

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  7. Chris

    How about an old (=cheap and well-seasoned) cast iron table-saw top? It already has slots and an opening that could work for the router with minimal machining. Just a thought...

    Tom

    ReplyDelete
  8. Tom,

    well, probably an old shaper table would work even better in that regard. Thanks for the input. Also, 'well-seasoned' as often as not, means cupped, bowed, twisted. The casting should be 'well seasoned' before it leaves the factory, however that does not seem to be the case judging by the commonness of non-flat machine castings.

    Or, maybe it is the case that certain castings, at least, by the way they are designed, may be prone to warping in the long term regardless of how long they may have seasoned at the factory.

    For that matter, probably the act of grinding the casting flat at the factory, even with a casting that may have been seasoned for a couple of years, causes movement in the casting to be precipitated. The casting leaves the factory dead flat, but a year or two later is no longer flat. It's like getting dried wood which is flat and straight at the lumber yard, then warps after you cut a slice out of it because of drying stresses introduced through the kilning process. While the wood can be conditioned at the end of the drying cycle to mitigate that effect, in the interests of speed and profit that step is not always done properly, or so it would appear.

    Someone wrote me a while back that the cored box castings, as seen on the Northfield products, are the most stable configuration for castings. However when I asked the shop foreman at Marena Industries in Connecticut about that, he was skeptical and didn't think it made much of a difference. How a casting is ribbed does make a difference, I have gathered that much from the reading I have done.

    ~Chris

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  9. I really like the woodgrain sketchup texture that is lighter on one side than the other, or however you did the change of texture to highlight the individual pieces or joints. -David, formerly Anonymous

    ReplyDelete
  10. Hello all,

    google blogger has been down for nearly two days with some sort of technical issue, and a comment I received in the interim has apparently been lost by the system. So, Ill take the liberty of posting it myself:

    David wrote:

    "I really like the woodgrain sketchup texture that is lighter on one side than the other, or however you did the change of texture to highlight the individual pieces or joints. -David, formerly Anonymous"

    Hi David,

    the wood grain texture issue is a thing with SketchUp and how it renders textures, not something deliberately done for effect, though sometimes I will make slight variances to opacity and shade to create those effects. Not in this case however. Thanks for your comment!

    ReplyDelete
  11. Chris

    Since you don't seem to trust cast iron, how about a granite router top?
    I know they use it for tablesaw tops now, so it can take the vibration. Its flat, stable, relatively cheap and machinable. I think you'll have to give up your infatuation with mitre slots, though. There are some fabulous granite counter fabricators (at least in Ohio). They could cut, drill and polish a beautiful top for you.

    Please consider this 'counter' proposal.

    Tom

    ReplyDelete
  12. Tom,

    funny! Yep, I've considered granite. It also sags over time from what I have gathered, though I imagine a thicker top would be better in that regard. I have no 'infatuation' with miter slots, in fact on the Jessem I have yet to make any use of them. The Ridgid table saw with a granite top that I saw a while back did have miter slots cut into the granite, mind you, so it it obviously a do-able task in granite fabrication.

    I will take a look into the costs of granite and its fabrication a little more though- thanks for the input once again!

    ~Chris

    ReplyDelete

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