Monday, February 28, 2011

Ming Inspiration (46)

My "day off" yesterday was actually 6 hours of SAT tutoring, but I was at least able to take a physical rest for a day. Today's work, which I had envisioned as being only about half a day's worth of stuff to do, was not actually completed in the 9 hours I put in. Oh well.

I spent most of the day with chisel and hammer, working on the stub portions of the central rail and main aprons and forming them into male dovetails. This began with some simple transferring of lines off of the battens:

Layout done, on to the ch-ch-ch-chiseling:

And more chiseling to hollow out under the central rail's raised 'T'-form rib:

More of same:

One side of one dovetail is then completed:

Let's see, 10 battens with dovetails on each end, two sides to work...that's 40 sections to deal with. Naturally, I started getting almost into mass production maneuvers with the chop out:

Keep the same tool in your hand and do as much as you can with it before putting it down - it's a minor efficiency I guess.

After a while, the dovetail tenons were processed on both sides of the central rail:

Then it was time to fit the battens to the long aprons and work the associated male stubs into dovetail tenons:

As before, layout is step one:

Then more ch-ch-choppin':

After clean out, the dovetailed stub is defined:

So all that chisel work took most of the day, and in the end the work was completed.

I then moved onto the tricky matter of cutting dovetail mortises on the underside of the table top panels. These mortises match some additional dovetail tenons that are arranged along the long rails in between the batten locations. In total, each long rail has 13 dovetail stub tenons, about one every 7.5", to secure the table top down to the apron's edge.

I set up the same jig I had made to cut the dovetail slots on the underside of the table panels, offsetting it to the middle position between the already-cut slots:

Of course, some careful layout and double-checking preceded any router work.

After a while, the dovetail mortises were roughed out on one panel:

Another view:

And not so long after, the second panel was through to the same stage:

That's where things ended up when it went dark and I decided to pack it in. Tomorrow I'll complete those dovetail mortises and then find some means to transcribe their locations to the aprons and cut the remaining dovetail males. Then I will trim the mitered returns and form tongue on them, and do a bit of test fitting. All being well, I should be able to have the panels fitted to the table frame by the end of the day. We'll see what happens.

Thanks for dropping by the Carpentry Way. --> on to post 47

Saturday, February 26, 2011

Ming Inspiration (45)

I think I might want to rename this thread Ming Perspiration. Another longish day today, and one in which I was pretty amped up with stress as I made each cautious triple-checked step along the series on the precious top planks. I find it quite exhausting, the intense concentration required at this point in the project. It's one of the costs associated with working with expensive material and close tolerances. I can now relate to how it must be for a jeweler cutting facets on a million dollar diamond or someone's treasure family heirloom....

Today I tackled the sliding dovetail slots on the back of the table top panels. Starting point was to carefully fit and align the jigs made yesterday, and detailed in the previous post) to the panels. Then it was time to rough out the slots using a guide collar and a solid carbide spiral bit:

The roughed-out dovetail slot, round 1:

A double check to see if I had a consistent depth, the target dimension being 0.2550":

Looks good:

Once all the slots were roughed out, I set a different size guide collar into the baseplate of the router, re-checked the centering of the collar to the collet, and then switched to the 8mm collet and Japanese dovetail bit:

That metal-working vise you can see on top of the jig is one of the treasures I brought back from Japan many years ago - - it serves to keep things flat and tight together. It's not convenient generally to use clamps in the middle of wide things, though sometimes one can spring press-down sticks off the ceiling.

At last, all the dovetail slots are completed and I can remove the jigs:

Here's a look at one end of the dovetail slot:

Next I chucked up the same 8mm dovetail bit in the router table:

I then routed male dovetails on 5 of the battens (the short side one with rod tenon mortises) - testing the fit as I went along. At last the dovetail was making an entry:

Fiddle, fit, fiddle, fit, and the first batten is pretty much there:

These dovetail slots are straight sided, not tapered. Normally, this would be a problem for fitting, however given that the remaining meat left in the board below the dovetail slot is only about 0.25", I can readily bend the board slightly to open up the slot and allow the batten to enter more easily. Once un-sprung, I can check the board with a straightedge and if the panel is kinked around the batten, then it is slightly too tight still and needs some adjustments.

It turned out that there were a few spots here and there where the router work hadn't completely milled the sidewall of the slot to the mark. Wish I'd checked more carefully before removing the jigs from the panels. So, rather than attempt to reset the jig, I used a Japanese dovetail plane to make small trimming adjustments where required:

Once this tool is set up, it will take decent shavings- I vastly prefer it to those short little Lie Nielsen replicas of Stanley #98 and #99 trimming planes (anyone want to buy mine?). Here's what I mean by decent shavings - it's end grain bubinga after all:

A little fit massaging, and the batten moves along nicely:

Once all the battens were fitted to that top panel, I was able to offer it up to all the rod tenons from the opposite side set of battens, to see if my jig had worked properly to align everything. Those rod tenons were fitted without room to spare to the rod mortise on the battens I just installed - they were slight interference fits actually, so I was pleased when the entire panel, with battens attached, slid down with a gentle swoosh noise onto the 5 rod tenons. Whew! It actually worked. So far anyhow....

Next step with that assembly was to trim the panel ends with their mitered spur returns. I scribed directly off the frame, measured and transferred the marks, and then used the kebiki to knife the cut lines:

I stay just a hair to the outside of my pencil lines with the knife so I have room to shave it down if needed to a good fit.

I used my circular saw to make the cuts:

A few swipes with the handsaw to sever the waste piece out completes the cut. The ends are now roughed out:

A closer look at the mitered return:

The next step there will be to trim back to the other line so as to leave the tongue.

All for today. I'm taking the day off tomorrow for the table, but Monday should see me through the completion of the work on these panels, hopefully even fitted up to the table. This coming week, probably around mid-week, will bring the final finishing and oiling.

Thanks for dropping by and if you have anything you'd like to add, of were wondering about anything you've read above, please feel free to leave a comment.

Friday, February 25, 2011

Ming Inspiration (44)

Post 44 in this thread. All of February's posts would appear to be devoted to this topic. It's been a good run - you'll find previous installments in this thread archived to the right of the page, and if you wish to read about something else, a mosey on over to the labels index might serve you well. Thanks for dropping by.

Yesterday's post ended with the table frame sitting, I mean standing, and ready for the next steps in the process:

The first task on the slate today was to level across all the battens and their associated landings at the points where they connect to the outer and central rails (landings which will become male dovetail stubs soon enough). I devised a jig which rode across the three principal frame members:

Some fiddling and router calibration was required, and then I went to work leveling the surfaces - I removed anywhere from '0' to about 0.015" of material or so from the exposed surfaces:

Another view, after a pass with the router:

I was guiding the router freehand, so I kept my distance from the central protruding rib - the remaining bit of wood left on the raised platforms on either side of that rib I simply trimmed down with a chisel:

It all went pretty well I thought.

Then I thought it was time to change things around a bit - why was I stressing out over those precious bubinga edge grain top panels, when a couple of pieces of Baltic birch ply would surely serve the same task so much more admirably? Why, with the plywood, any concerns about wood movement would just dissolve into irrelevancy and I could make the ply fit the top frame with little to no gaps. That sounded like a good idea! I could even stain the ply to match the bubinga.

So I tossed the bubinga top panels in the trash- they were starting to bug me anyhow - and commenced fitting the pure, lovely white Baltic birch panels:

What do you think of the change? A bit radical I guess, but it's really time I starting getting hip to these modern materials and stopped being such a curmudgeon. Solid wood is so yesterday - that's what they tell me.

Of course, I'm pulling your leg. I hope I had someone going though, even just a little bit!

There was in fact a bit of cutting action today involving the bubinga top panels. I did a little scraping on the back side of the problematic one, which was still quite cupped, and I decided to put it to one side and work the spare piece of material (the leftover slab from earlier in this thread when I had the top panels re-sawn) into a substitute role. That spare slab had once been 1.25" thick or so (or was it 1.5"?), but after a session of many light passes through the planer upstairs, then many, many passes through a thicknesser, I had a new 0.5200" thick replacement. No pictures of that though, however it is, to my considerable relief, nice and flat. Yes! Looks like the crisis of the warped table top panel has been sidestepped, at some loss of material of course. I probably planed away $300 in wood on that one slab....

So, what was up with that last picture and the Baltic birch ply? Well, I am using it to make a large two-piece jig for routing the dovetail slots on the backside of the table top panels. I realized a while back in one of those late night toss and turn sessions that one of the challenges in this project, given my joinery choices, would be getting the dovetail mortises on the underside of the top panels in perfect congruence with the battens. One can imagine that if a batten on one end was slightly misaligned or not exactly on spacing, it would present assembly problems, as the battens must get pre-fitted to the table top as a group. Then that assembly must engage with both the central and outer rails - counting the twin stub tenons and yatoi-sen slot mortise on the outer ends, and the housed box tenons with rod tenons on the central rail, there were 25 points of simultaneous engagement. Yep, it was pretty critical that the alignment of the dovetail battens, in situ, was perfectly reflected on the underside of the table top.

My solution was to create a giant template which referenced directly off of the batten locations, a template that could then serve double duty as a means of producing the dovetail mortises. That was the theory at least. Let's see what unfolded.

With the plywood template secured to the table top in the required position, I flipped the entire top, sans legs, over:

Then I pulled some 2.5" ply strips tight against the sides of each batten and screwed them into place to the master template halves:

I then flipped the entire works over again and ground the protruding screw tips down, a step which later proved to be completely unnecessary:

With both sides done, I extricated the templates from the table frame assembly, and commenced adding small pieces to extend the templated lengths of the battens:

I then had to scab on a strip to one side of the template and place small extension pieces on that side too. Once all that work was complete, I used my jigsaw to rough out the openings between guide strips:

A trim router was then used to trim the openings flush to the guide strips, as seen above.

Here's one side template/jig complete:

Another hour or so later and the other side was also done:

By that point it was getting late in the day and I was pretty tired, so I decided to table the next steps, until later. Sorry - I couldn't help that rather bad play on words!

More to follow tomorrow as I apply these jigs to the table top panels. That should be entertaining to say the least, and a little stressful too.

Hope to see you then! --> on to post 45

Thursday, February 24, 2011

Ming Inspiration (43)

Post 43, with previous entries to be found in the 'blog archive' to the right of the page. Welcome back.

Today was a day punctuated with various other activities, so it wasn't quite as productive as recent days. Nevertheless, I have pictures to share which I think readers may find of interest.

Last time, I gave an account of yatoi-sen, and showed some steps in making them. I'll start today with a continuation of that process. With the lower end tenons completed and fitted, I next worked the upper ends.

First I cut the yatoi-sen to exact length, then rough dimensioned the upper end tenons, which will become a special type of dovetail soon enough:

I also cut crosswise notches in the pieces with the tablesaw, notches which define the shoulder for the cross-wise fixing pins, or shachi-sen:

I then set those aside, as I wanted to get the mortises done before the dovetail tenons. I figure it will be easier to size the tenons to their mortises, in this particular case, than the other way around.

First step was to use the kebiki to incise the lines for the bottom surfaces of the mortises, which are located on the lower ends of the mitered faces of the aprons:

A few steps later on, I had the mortise half largely cut out:

Notice that the incised line done earlier remains about 1/8" (@ 3mm) below the mortise. The dovetail tenon has a special shape to help protect the dovetail from short grain fracture issues, so the mortise has to reflect this shape. This will make more sense perhaps when I show the completed tenon in a future post.

Later I am chiseling the waste away to complete the mortise (half):

The completed dovetail half-mortise - one detail is that the mortise is slightly longer than the tenon, to allow for any slight fitting irregularities which my crop up later, and as a result I was a little less picky about have the mortise end walls perfectly cleanly cut:

Seemed like a good time to reassemble the table frame once those mortises were done - this time with the battens as well:

Another view:


Another view:

A closer look at one end, with the legs and Giant's Arm braces fitted:

May as well take a step back for the big picture:

Another angle:

Then I decided to take a look at the top panels. I took them upstairs and with some degree of nervous apprehension, cross-cut and ripped them down to dimension. Talk about workmanship of risk - David Pye would be pleased. The risk in this case, however is not exactly what Pye was referring to - you see, these two 20" wide edge grain bubinga planks, if I were to mis-cut them in some sort of terminal fashion, would be about $5000 to replace due to the sort of plank they need to come out of - I simply cannot make any mistakes with them. Measure 6 times, then cut.

So far so good. The cross-cutting and ripping went fine, and I placed the planks on the table and rearranged them a few times. I also asked John and Barry, who have a shop upstairs in the same building, to come down and give me their $0.02 in terms of the arrangement of the two planks. I think we rearranged those planks 10 times over.

In the end, I selected this pattern:

Tomorrow promises to be a longish day, as I hope to complete all of the joinery to attach that top to the support structure below. Let me say this: I can't wait to see this piece in oil!!

Thanks for coming by today my friends. --> on to post 44