Tuesday, September 9, 2014

A Square Deal (13)

Post 13 in a series describing the design and construction of two tables in figured solid bubinga. The first post in this series can be found here, with subsequent posts linked at the bottom of each entry.

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At long last I can return to this project, something which I have been anticipating for a while now. Here's a view of the two tables I'll be building:


I had rough cut the components for the two tables and let them sit for a good couple of months, so they had ample opportunity to move about all they were likely to move. I put fresh knives in my jointer and planer and took them down in size, leaving off with about 1/32" (0.8mm) to spare, as this was a close as I felt I could safely get with the small amount of tear out I was experiencing off of the planer.

Today I took the parts to Berkshire Products in  south western MA, a 2-hour drive, to have the pieces run through their SCM 'Sandya' thicknessing sander. Their machine was the most accurate and modern I knew of within driving range, however it wasn't quite as wonderful a device as I was thinking it might be. The digital readout for thickness on the machine, though reading in the thousandths of an inch, turned out to be out of calibration by nearly 3 hundredths of an inch - and showing a larger dimension than actual of course - which resulted in the first two pieces run through going slightly under dimension. I quickly adjusted the numbers I asked for, and the rest of the pieces were run through without incident and the work was done in under an hour.

Returning to my shop, I unloaded the material and then went to put a fresh set of knives in the Super Surfacer. The insert-knife stock is easily removed by taking out 5 bolts, though strictly speaking the knives can be pulled without taking the knife holder out at all. I prefer to remove it as I can more easily clean it up and inspect it for condition. With the holder out, the osae-gane for the knife is removed with six smaller bolts:


With a new knife fitted in place- it snaps into place with the aid of several incorporated rare earth magnets, the osae-gane is re-positioned - here you can see one of the two metal tubular pins which serve to reference the position on the lower edge:


Interestingly, with this quick-change knife system, the osae-gane is not positioned especially close to the knife edge, as it would be in a hand plane:


The trick Kanefusa uses to obtain a chip-breaker effect it to machine the chip breaker directly into the back edge of the knife, as this drawing shows:


Component 4 is the knife. If you look closely at the photograph shown just before the above illustration, you will be able to see the chip-breaker groove in the knife's rear surface. Neat!

With the knives fitted back into the machine, it was time to run some curly bubinga through. I've read some accounts where people state that Super Surfacers aren't so good for hardwoods - you know, those Japanese carpenters mostly work softwoods so none of their tools are suitable for hardwoods, etc., and one would think that given bubinga is pretty hard stuff, and that it is curly to boot, this would form some sort of insurmountable challenge for the machine. Well, not so much:


The surface left behind was completely tear-out free, even though the grain reversed every few inches:


I don't think I could do any better with my handplane in this material. I decided to take all the stock down to dimension with the surfacer. When I was done, there was quite a bit of 'bacon' under the machine:


By hand this would have taken me most of the day, with multiple resharpenings and likely some frustrations here and there with tear-out. Instead I was done in 40 minutes:


I am very happy to have this machine in my shop.

I was able to run the side table top through the surfacer as well, by removing one of the side rails and running half the board at one time:


Other than the table legs for the side table, which are slightly under dimension as a result of the initial sander passes this morning, all the stock is straight, clean, and within a few thousandths of an inch of the target dimensions. I will be able to adjust for the slightly undersize coffee table legs - they are only undersize by 2 hundredths of an inch.

I'm still ironing out minor design details, but will certainly be proceeding in on the coffee table soon, right after I have put the breadboard ends on the side table. As this process is much the same as the one already shown for the coffee table, I won't be photo-documenting and describing the steps. Look for more post in this series in coming days and weeks though.

Thanks for dropping by the Carpentry Way. On to post 14

8 comments:

  1. CHRIS;
    The grain looks great!You have the bacon bring on the eggs!Can't wait for the rest!Keep up the good job,thanx for all.
    J.T.

    ReplyDelete
    Replies
    1. JT,

      your dedicated readership is greatly appreciated!

      ~C

      Delete
  2. chris,

    i only use kanefusa blades. the cut finish is great. my only complaint is that they don't hold an edge very long. luckily kanefusa is nearby and i can get them sharpened with a great turn around time. i've also been building up the assortment (up to about 30 blades or so) to limit the downtime and i get a better deal with batch sharpening. let us know how your edge holds up.

    fig

    ReplyDelete
    Replies
    1. Fig,

      well, that's the experiment here, to see if the quick change knife system seems a reasonable alternative to the conventional knife and attendant grinding machine. Interested to read about your resharpening - how many times can the blades be resharpened? Of course, having Kanefusa do it makes sense as they can regrind the chipbreaker groove into the back of the blade. I wonder if it would make sense for me to send my knives also to Kanefusa for sharpening, in batches of 10, say?

      As for durability, I've only been using the knives so far on Burmese teak, and they really don't last too long at all. I found the same with the teak though when using HSS or M42 Tersa knives in the planer and jointer, and it took a switch to Tersa carbide knives to obtain decent durability. It seems that Kanefusa does not offer a carbide knife option though, and not sure it would be adequately sharp if they did....

      I'm hoping the durability of the HSS knives will be a lot better when it comes to working the small mountain of Port Orford Cedar I have to deal with later in the fall. I was pleased with how well they did with the bubinga today.

      Thanks for your comment!

      ~C

      Delete
  3. Chris,

    I've been waiting for the next entry on this build. Not only do i love seeing these tools that I've never heard of before but your level of skill is in-matched. Keep it and and keep creating these post's. I can't wait to watch you create some of the intricate joinery.

    John G.

    ReplyDelete
    Replies
    1. John,

      very kind of you, however I have a long way to go yet in terms of skill. There are some very talented people out there and it is simply the case they don't share publicly for some reason or another.

      I'm glad you're enjoying the posts and I think you'll enjoy the joinery that is incorporated in these two pieces.

      ~C

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  4. Love the figure in the top. assume that it will look 3-D when some finish is applied. Any video of the super surfacer in action? Thanks for taking the time to post these projects. (Between the gate and these tables...looks like your "plate is full") We all look forward to all of them.

    ReplyDelete
    Replies
    1. Joe,

      thanks for the reminder about video of the Super surfacer in action. It will happen.

      Besides the gate and tables there is the work for the artist in New York, which is ongoing, yet intermittent, and the work for the online study group, which is also ongoing and somewhat intermittent.

      Thanks for your comment and glad you are looking forward to more posts. Keeps me motivated for sure.

      ~C

      Delete

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