the Carpentry Way: A Square Deal (10)                                                          

A Square Deal (10)

    
Back to the shop for some furniture work, after the past week's activities revolving around the Boston project.

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After rough cutting the tenons by way of my portable grooving machine last time out, the table top had remained well behaved. Every time I am at the shop I check it with a straightedge and make any required minor adjustments to the clamps or the dunnage positions upon which the slab has been resting. So far so good, but every time I am faced with doing further cutting on the slab I tend to verge on a state of vigillance in regards to whether the top might move as a result of further material removal. As time goes on with this process, I have become more relaxed and confident about the outcome, but with solid wood there are always unknowns so one needs to remain somewhat alert to any changes as a result of cutting. I've got the sheep in the pen, so to speak, and hopefully we're at a point where the border collie need only raise an ear and the sheep will decide against further misbehavior.

Even when I'm working on other projects, I still keep this one in mind, and consider the details often, and revisit the drawing to explore new ideas that arise. I have made a slight revision to the breadboard end detailing, just a slight dimension change and have increased the number of tenons to three since last time I worked on this.

My plan for today was to complete the trimming of the end of the table top tenon shoulders, and then process the groove on each side which are engaged by tongues on the breadboard ends. My weapons of choice were two new router bits, a Whitesite 'Ultimate' pattern bit, on the left, and an Amana flat bottom dado cutter with bearing (center):


A Festool collet sits on the right. This is the second of these new bits from Whiteside I've acquired, which utilize developments in cutter geometry derived from CNC routing. They're good, but a bit pricey.

I had a couple of bits of aluminum plate left over from the jig I fabricated for the MFA project, and these turned out to be the perfect thing for aligning the top and bottom edge guides:


Here's the basic set up:


 After some careful mark out and triple-checking, I trimmed the tenon cheek and shoulder. The finish left by the Whiteside bit is excellent, with zero tearout:


Another view - these trims were accomplished using a climb cut:


The board is then flipped over  - taking pains not to disturb the metal guide rail positioning - and the opposing cheek and shoulder of the tenon are then trimmed. The target dimension for the tenon thickness is 0.5000":


Now onto the other end of the board. Here I was also working to achieve a target dimension after trimming for the entire top's length, so I was carefully checking as I set up. I have found that a lamp with magnifier is quite helpful for such tasks as spotting the marks on a ruler with 0.5mm graduations:


A look through the magnifier - I'm seeking to set a mark 71.5mm back from the cut line (this, the measured offset of the Whiteside cutter from the router base's edge), which will reference the metal guide jig:


Another check is made on the other end of the cut, again, looking to mark an offset of 71.5mm from the mark:


 Check the clamps were tight and everything in order, the completed the tenon trimming. I also took an extra minute and plowed out a few notches from the waste portion of the cut on each side as a means of reducing the wood grain's leverage to move the slab:


This step was probably not absolutely necessary, but it didn't hurt anything either. I wasn't sure at that point if I was going to remove the rest of the waste from the tenon cheeks or not on today's slate.

Next step was to plow out the grooves for the breadboard end tongues. Changed out to the Amana bit, set it up, and made the first cut:


At the far end of the cut I clamped a block in place to prevent any tear out as the cutter exited:


Flip the board over and repeated the process on the other side:


Then repeated the same two cuts on the other end of the board, to complete this stage.

After some mulling, I decided I could remove the waste from the tenon cheeks without affecting later cut out steps. The shaper seemed like a convenient way to accomplish that task, so I placed an Aigner auxiliary support table on the front, slid the sliding table forward a bit for extra support, and adjusted the cutter to position:


A closer look at the material removal nexus:


After a first cut had less than ideal quality, I decided to use a different cutter and reversed the feed direction. Here I'm halfway through the last tenon cheek:


The cutter was set to leave about 0.01" of waste proud, which I then removed with a hand plane:


After all was said and done, the tenon is now cut out on both ends of the slab, and the slab has remained doggedly flat throughout the process:


A final look at the joinery after today's work was complete:


Of course, I'm not planning to have one mega-tenon here, there is still a fair amount of cut out remaining to define the three tenons, the stub tenon, and the end joinery work after that. Things are rolling along well however, so I'm feeling pleased with the progress so far.

Thanks for coming by the Carpentry Way. On to post 11.