Thursday, July 28, 2016

A Ming-Inspired Cabinet (67)

Work has slowed to a crawl on the cabinets of late. With a newborn, spare time tends to be more limited. In fact it passes most peculiarly at times!

Our son is now a month old:


Getting to the point where he can make eye-contact and is making facial expressions of all kinds. It's cool to see this unfold.

I manage the odd 2-hour block of time at the shop here and there, and have moved the drawers along a bit. In the previous posts in regards to the BCM Maker Faire, you can see that I managed to get one drawer dry assembled to bring along as an example of joinery work. I thought I'd post up a few more details about the process of putting the drawers together.

One of the seeming more mundane tasks is drilling holes to mount the drawer handles. These are spaced 65mm apart, and are offset 15mm up from the centerline so as to place the handle in a centered position overall. I used the mill to position and drill the holes from lay out marks:


It's simple enough drilling holes, and with a brad point drill and backing piece, no issue cropped up with blow out. However, given that there are three different drawer heights and two different drawer widths, it was paramount to keep vigilantly organized so as to not place any holes in the wrong position. It would be all too easy to do, especially given my rather ragged sleep patterns of late, and one mis-placed hole would mar what is a whole bunch of work already completed. I managed to get through all 18 fronts without any mishap thankfully.

I had used the mill to rout both the dadoes and the mortises for the drawer side connections, and employed the hollow chisel, sans auger, to square up the mortises:


The mill allowed great positioning accuracy in cutting the dadoes and mortises, and following with the bare hollow chisel made for an elimination of the off-center auger holes that can occasionally occur when using the hollow chisel+bit as per normal. Not the most efficient process to be sure, but the results were as I desired so all good.

Once the drawer side connections were complete, I then did the same mortise squaring for the drawer rear wall connections, except that I completed that work entirely by chisel.

Here's the first completed dry-assembled drawer being test fitted to the carcase:


This type of drawer has greatly reduced areas of contact on the sides, and the high precision offered by the mill when cutting the joints meant that these went in snugly, not too tight, not too loose, the first time:


The other side:


Should the drawer side runner ever bind to the carcase due to swelling from moisture gain, adjusting the fit would be very easy as compared to a regular drawer in which the entire drawer side is running against the carcase. If the fit became overly sloppy somewhere down the line, sistering on a small strip of wood to the side of the runner and re-establishing a perfect fit would be straightforward. The drawer runners, being wide, nearly triple the area on the loaded portion of the drawer side, ensuring considerably extended durability for both drawer and carcase.

I'm totally sold on my adaptation of the NK drawer design and plan to employ it in all future cabinetry projects involving drawers.

A view from above:


A couple of sample timber joints are laying in the drawer, not forming part of the assembly of course.

A view of the dry-assembled drawer before the handle holes were drilled in the front:


Side:


The tenons on the drawer rear wall are yet to be kerfed and (double) wedged, hence the gaps at the sides where the mortises are flared following cut out. As the drawer sides do not rub on the carcase, I can leave the wedged tenons long without any concern that they might scratch the carcase in passing.

Rear:


A slot will be cut in the drawer floor directly under the mid-point of the drawer rear wall's lower edge, so as to fit a screw which will hold the drawer to the rear wall. I'll tackle that work when all the drawers have been dry assembled and fitted.

With the handle fitted to the front, and the drawer front fitted into the cabinet opening, the drawer can now go all the way in;


Fitting the drawer front took very little time, and I found feeler gages most helpful for that process. The drawer front lower edge also clears the carcase by about 0.01", as the drawer itself rides on the runners, allowing the drawer front to pass the carcase rail without rubbing.

Another view:


One more for luck:


I'm looking forward to seeing how the entire blank of drawers will look when in place.

The handles come from a specialty tansu hardware supplier in Japan and is in a shi-bu-ichi finish. The drawer front will be finished with tinted Enduro Var in the same manner as the rest of the cabinet. The remaining drawer parts will be left without finish, though i may swab something on the end grain portions to slow moisture transfer. Everything is quartersawn as it is, so movement should be absolutely minimal.

All for this pass by the wicket. Hope you enjoyed your visit to the Carpentry Way. Post 68 is next in this series.

Sunday, July 24, 2016

BCM Maker Faire (follow up)

I spent 10~5 yesterday on the boardwalk in front of the Boston Children's Museum with a table presenting samples of Japanese joinery and my woodwork, most of which could easily be assembled and disassembled by small children. Here's a snap of my table:


It was in the 90s (˚F) yesterday, so I drank a lot of water and was at least in some shade under a large tent with many other exhibitors. The vast majority of exhibits concerned robotics, battlebots, R2D2 controlled by joysticks, and the like. Booths devoted to more old fashioned things, like mine, were rather few and far between. Across from me were two others with old school stuff, one dealing with Japanese looms and weaving, and the other a project to teach poor urban Junior High kids how to make a plywood skiff in 11 sessions.

I had a lot of kids come by with their parents and it was a pleasure to watch them discover something about joinery as they took the models apart and put them together. Some kids were quite entranced and I had a few return visitors. Some parents knew a little something about the subject area of joinery, though many were as uninformed as their kids. Probably the two most interested kids that stopped by were a pair of 12 year old girls who asked me a great number of questions and were quite fascinated by the whole thing. That was rewarding.

I certainly got a lot of questions, and some, interestingly, cropped up time and again.

Here are the top 3 questions I received on the day of the Maker Faire, in order of frequency:

  • "Did you use a laser to cut that?"
  • "Are these puzzles?"
  • "What is all this?"

I heard each of the above questions at least a dozen times, from both children and adults. One adult, of Indian background, came upon my table with his young daughter and, scanning the scene, asked, "what is all this?". After starting to hear my answer, he snorted that, "there's nothing here for my daughter to interact with." As he started to move off, I said, "well, actually...", and I showed his daughter who stood in front of him, around 8 years old if I were to guess, how to take apart one of the joints. As soon as she began to play with it, he pulled her away. Off to the next thing.

It is interesting to see how people's preconceptions and snap judgments color how they perceive reality.

The questions about using a laser were humorous if it weren't for the fact of their frequency and that adults were usually the ones asking that question. A lot of people just don't have any familiarity with wood joinery, so I was able to at least introduce something new to them, but, it is a little sad to me all the same. Many, upon seeing an assembled joints, assumed that the parts were cut in the same manner as a jigsaw puzzle, and were flummoxed as to how I had made the cuts with, to them, nearly invisible lines. So I did a lot of explaining about that.

One fellow, a Chinese guy who I think was from MIT's robotics lab, seemed dumbstruck that wood could be cut to fit tightly together without the aid of CNC equipment. He kept smiling in puzzlement and seemed at a loss for words. That was a curious moment.

Quite a few adults asked me if I used CNC, and when I told them I used rather more mundane tools to make the joints, were almost in disbelief or astonishment. Then I told them that the joints were deliberately made a little loose to aid in being interactive, and some had trouble taking this in. It's as if they no longer imagine humans can do close-tolerance work. I pointed out to one person that the most perfectly round sphere ever created, was polished to final roundness by hand by Achim Leistner, as "his precision in handcrafting spheres was [found to be] superior to any machine".

It was a long day, starting for me at 6:00 am, and I was pretty much on my last legs when I got home, a 2-hour drive. I think if I participate next year I can find a few ways to improve my presentation. It seems that joinery remains outside the scope of a lot of people's awareness, so working to improve that is certainly worthwhile I think.

Thursday, July 21, 2016

BCM Maker Faire

I'll be at the Boston Children's Museum this coming Saturday to participate in the Maker Faire.

As part of the preparation for that, I have made a few joinery models, including these two splicing joints:


The models, of four in total, were commissioned by the Museum for the purposes of educating children about Japanese carpentry. Part of the challenge for me was to make them just loose enough to allow for ready assembly and disassembly.

The shorter of the two splices, or tsugi-te, is a simple twin stub tenon affair, ni-mai mechigai hozo tsugi:


The longer one is an archaic form of half-lapped gooseneck, koshi-kake-kama-tsugi:


Partial separation reveals the intersections of the parts more clearly:


More separation, without anxiety:


Another view:


How about one more for good measure?:


I'll also be bringing along examples of work-in-progress, like this cabinet drawer, a sliding door with latticework, and so forth:


I also plan to display some of my Japanese hand tools.

If you're in the area and have a moment to spare, please do drop the Maker Faire by and say 'hello'.

All for now - thanks for visiting the Carpentry Way.

Monday, July 18, 2016

La Menuiserie Study (III)

In the last post, I introduced Plate 1 in the text La Menuiserie, specifically volume 3 of aa multi-volume encyclopedia on the topic. Plate 1 detailed the first significant exercise in a chapter entitled Eléments de géométrie dans l'espace. The study in this section concerns the intersection of various solids, like cones, parallelepipeds, cylinders, and spheres. I've worked my way through all of the remaining exercises in this section, and was pleased to find the layout techniques worked perfectly. In fact, the technique for determining the intersections between solids is fairly uniform between different cases, with one exception, to be mentioned below.

Plate 2 covers the intersection of a sloped square section stick piercing a cylindrical post:


Plate 3 deals with the intersection of a sloped smaller cylinder meting a cylindrical post:


Plate 4 gets us into cones, the first problem dealing with a cone pierced by a horizontal cylinder:


I will now admit I am a cone 'head'.

Plate 5 is a cone pierced by a smaller vertical cylinder, offset from the centerline of the cone:


Plate 6 was the most complex of this set, involving the intersection of an angled cylinder partially occluded into a cone:


Plate 7 was a different sort of beast, the intersection of a vertical and a horizontal cone:


Here, one can not pull points in the same way as with other intersections, but must construct auxiliary planes which intersect both cones.

Detail:


If you're hankering to see some sort of woody manifestation of the above type of problem, maybe a bit more difficult, volume dialed up to 11, there are no shortage of maquettes. This one could be called, "let's have fun with scalene cones":


The preamble to a carpentry challenge like this - the minimum 'get a foot in the door' move - would be mapping the surfaces of intersecting cones.

It appears that the upper angled cone can be removed easily:


Scalene fun, Part II - it is the same model, taken off the support stand:


Credit to: RWLV

Finally, there is plate 8 which deals with a sphere occluding a cone:


This was a simpler problem than the cone meeting cone, as it turned out. Almost easy.

The next section in the text deals with regular plan hips, and area with which i have some familiarity, so it will be interesting to learn some new approaches.

All for this time. If you're feeling inspired - and I hope you are- go lay down some lines and cut some wood.

Saturday, July 16, 2016

La Menuiserie Study (II)

Post 2 of a series.

--------

After working my way through the first 70 pages of the French text La Menuiserie, I at last arrived at the keenly-anticipated first meaty exercise to be detailed, on Plate 1, entitled, "Pénétration biase de deux parallélépipèdes rectangles":


The term 'parallelepiped' is a word which, though seldom encountered by most I would suspect, is a part of the English language. While the term describes a solid comprised of 6 faces which are parallelograms, when you recall that both a square and rectangle are a form of parallelogram (i.e., are 4-sided figures with two pairs of parallel sides), you can see it is a therefore a term with which one can describe a S4S stick of wood. Try throwing that term out to your co-workers on the job site one day and see what sort of response you get - hah! It's a term you'll come across in some English 19th century woodworking texts.

The problem is one of a square section vertical post being pierced at an angle by a smaller square-section stick. Note that the smaller stick crosses the post at a given angle, and is not centered to the post, and is itself rotated to a given angle. They are not looking to provide an easily-solved example. The purpose of the Plate 1 study is shown to the right of the sketch above, the développement, which is an unfolded view of the four faces of the post, showing the position and shape of the mortise lines.

I was psyched to dig into this first plate in the text. I cranked the hand wheel, the light's flickered, a screech of a leather belt and SketchUp came to life. I faithfully drew out the plate in 2D and produced the required unfolded, developed view of the mortises. It seemed straightforward enough to follow the method shown.

Curious to check the result, I then flipped the unfolded view upright, and proceeded to fold the faces inward until I produced a '3D' post. Then I connected the mortise corner lines together within that post. All seemed well as planes were formed within. Then I drew up a second smaller stick of the designed dimension, rotated and tilted it to the correct position and placed it into the through mortise. Jolly nice and all, except it was not even close to a decent fit. Not only was the mortise itself non-square internally, wall to wall, but it was not square dimensionally either.

Huh? I figured I must have blundered somewhere so I drew the entire exercise again, only to reach the identical outcome. Something was haywire. I then decided to do a reverse engineering, making a post without any mortise layout, using the plan and elevation views to place the smaller crossing stick in the correct position and then intersecting the two 3D parts so as to produce the mortise lines on the post. Then I unfolded that post section and laid it flat atop the drawing to compare, thinking that maybe I had simply put one of the mortise corner intersection points in the wrong place or something like that. Here's the overlay:


As you can see, while the overall mortise outlines are similar in overall appearance, they have only one point in common, at the top, at each side. The lines associating to the white background are in the correct places, while the colored pieces in the background are part of the development done from the original drawing.

The text had to be wrong somehow, as the 3D did not lie, and later that evening, while pacing and bouncing with the baby on my shoulder, I could see what the issue was: something was causing the layout of the mortises on the post to be distorted, and I had an idea as to what the culprit was.

The following morning, when I had a little time, I went back to the sketch and tested out my theory, and then was able to confirm my suspicion. Here's the problem area of Plate 1:


The square labeled Se1' through Se4' is the cross section of the sloped crossing stick. From the four corners, lines are projected plumb down to produce Report Line 'A'.

Report line 'A' is used to draw the plan view of the stick:


I suspected that the way Report Line 'A' was established was the kernel of the problem - that report card gets an 'F' unfortunately.

I placed the 3D stick directly over the plan view to check whether the plan of the stick conformed to the actual outline of the stick - it clearly did not:


A closer look with a couple of width measurements indicated for comparison:


A roughly 4mm difference in plan view width, not to mention the discordant positions of the arris lines, would definitely account for distorted mortises in the development of the mortises on the unfolded post faces.

Just to clarify, the actual crossing piece section conforms perfectly with the elevation view on the drawing, as the traces dropped down to the floor indicate, and is the exact size of the cross section depicted on the elevation view:


Anyhow, shortly afterwards I sorted out the problem with the text's drawing. The projection from the crossing stick's cross-section should not drop down plumb, but project square to the stick, like this:


I then swung the lines down to create a similar looking horizontal Report Line 'A' as the text had shown. These lines could be further extended, if desired, and reflected on a 45˚ line to directly produce the plan view lines for the piece.

With the revision to the report line in place, I re-drew the plan view of the sloped crossing stick, and from there drew out the development one more time:


The 3D stick was then unfolded, and was placed atop the drawing development for a look-see. The mortise outlines on the development and the unfolded stick conformed to one another exactly.

Another view of the post and post assembly with sloped piercing cross piece:


So that was not a promising start to the eagerly-awaited 'meat' of Volume 3 of La Menuiserie. Planche 1, presumably the most basic exercise, had a serious error.

Well, in truth the method shown was correct save for that one issue (projecting the lines for the 'Report Line 'A'), however that one little mistake threw the development out by more than a little. I'm puzzled how this could have gotten past the editors of the book. Did no one actually make the project? The drawing in the book looks to be produced in CAD, so it seems like they never modeled it in 3D. Or was it so basic a model that a lazy or simple mistake was overlooked? Who knows....

As things have turned out, over the subsequent 7 plates which I have completed, all dealing with the lines of intersection between solids, have all been spot-on, so I think that first plate has an unfortunate error in an otherwise excellent text.

Thanks for dropping by and stay tuned for part III.

Friday, July 15, 2016

La Menuiserie Study (I)

Menuiserie is a term which translates into English as 'joiner's work', an almost meaningless term in the US these days, or as (finish) carpentry, or cabinetmaking, and furniture making. Like finish carpentry compares to rough carpentry, menuiserie compares to charpente. In charpente there is some joinery, but a lot of the work is spiked together, and timbers are generally not backed to conform to a plane but are rotated to present one face to the plane and leave the other one out of plane. In menuiserie, the timbers are joined and are shaped to conform properly to the planes they meet or define, and in this respect menuiserie shares a commonality with Japanese carpentry. To say that menuiserie is simply cabinetmaking or carpentry is a little misleading in english, given the types of work suggested by those terms these days. Menuiserie overlaps a number of areas of woodwork and is probably best understood as joiner's work - highly finished framed and joined structures, including furniture, built-ins, interior millwork, doors and windows.

One of the classic texts in menuiserie is L'Enseignement Professionel Du Menuisier, by Léon Jamin, dating from the mid-1800's. Comprising 3 volumes, it remains on my wish list. What I do have as a reference on hand is a volume from an encyclopedia on the topic, put out by Les Compagnons Du Devoirs, entitled La Menuiserie. Volume 3 comprises a text book, of large format, and a separate folio of plates:


I've had this book for some time, and yet hadn't made a dedicated study of the material. With a newborn, I now find myself at home a lot more, and with the occasional hour here and there to spend as I might like. So, when not trying to catch up on sleep I have delved in to this modern text, starting at page 1 and drawing every exercise in the order they are presented.  La Menuiserie presents a fairly systematic path through the material, beginning with basic geometry exercises like drawing parallel lines, drawing perpendicular lines, triangles, angles, polygons, etc. Thought that material fas already familiar to me, I drew the examples, using SketchUp instead of paper, compass, etc.

From the most basic stuff, La Menuiserie moves into drawings of ovals and various curves, then to ellipses, including a cool method that I had also noticed previously in my Mazerolle text but had never explored:


It's a very easy-to-remember and accurate method to produce ellipses, and if anyone is interested I'd be happy to show how to do it step by step.

After ellipses the study moves to curves developed on slopes, like this one for example:


An application for this sort of thing would be laying out a domed roof underneath a pent roof - as the following example on the right shows:


Next the text deals with drawing the line of the 'policeman's hat' (chapeaux de gendarme) - here are two methods:


Next, the volume deals with spirals of various types:


Archimedean spiral on top, two-point spiral below.

Spirals on three points, four points, and six:


And extension on the theme of spirals are volutes. Here are four different types:


All of the above exercises are merely a preamble to the sections to come. The first part of the more involved study is titled Éléments de géométrie dans l'espace. In that chapter the exploration commences with a consideration of the basics of descriptive geometry,  orthogonal planes and the forms of the basic solids like prisms, cylinders, cones, pyramids, and so forth. At this juncture, the supplemental box of plates still hasn't been cracked yet.

There are a series of exercises to develop the surfaces of cones, and then truncated cones. 

Here's the development of a right cone with sloped truncation:


And this is the development of an oblique cone with sloped truncation:


Notice the characteristic shapes of the developed surfaces in the above two examples? With a right cone, an oblique cut of the cone produces a developed surface which has a horseshoe-shaped cut. With an oblique (or scalene) cone similarly cut, the developed surface has an 'M'-shaped cut line.

Now, as I worked my way through the above two exercises, there would be times when I would refer to the text, which of course is in French. At least it is not 19th century French like the Mazerolle book, but it still exercises me a bit to translate. I did, after all, flunk out of French 11 in high school. At one point I decided to look on the web to see what else I might find on the same topic of developing conical surfaces -perhaps there were other methods worth looking at - and I came across a French Wikibooks page on the topic, titled Traçage en chaudronnerie et tuyauterie, which I translate as 'Templates for Boiler and Pipe Work'. Developing surfaces like cones and cylinders is a standard sort of thing for fabrication of pipes and ducts.

Here's what that page showed for the development of a right cone with an oblique truncation:




The developed surface shown was contradicting the La Menuiserie text I had, with an 'M'-shaped development from a right cone instead of the horseshoe-shaped development. Hmmm....

Well, only one of these developments could be correct (or neither - or possibly both somehow). In SketchUp there is no convenient tool with which to unfold curved surfaces flat, so I drew a scalene polygonal cone and unfolded it (which was a tedious task) to see what shape was produced:


There we have it: the 'M'-shaped cut line associates to the scalene cone, as my text showed. That French Wikibook page was incorrect. I went into the history for that web page, and note it has been up for 6 years, the diagrams edited for clarity at different times, and it has apparently been in error on that development the whole time. Funny how things go like that. I hope it hasn't confused too many boilermakers or pipe-fitters in the interim. Someone must have mixed up parts of two sketches, perhaps?

EDIT: A reader pointed out that the shape of the cut line on the developed surface is related to where the cone is cut to be unfolded (i.e., at the longest or shortest length), so my above conclusion about that Wikibook page is in fact erroneous. If I had chosen to unfold the above cone at a different point, I would have concluded differently.

I'll continue this account in some further posts. A series begins. Thanks for visiting the Carpentry Way. Part II is next.