Saturday, December 24, 2011

Contemporary Shaker Style Table -- Building a Base

Happy Holidays!

While the second step of the finish on my Hammer-Beam Tables is drying, I'll take the opportunity to post about another recently completed project.  This table is a variation on the Shaker Candle Stand idea with a couple of contemporary updates.  First, it is made primarily from black walnut -- one of my favorite woods to work with hand tools.  Second, the design of the top includes includes a strip of figured maple.  I suppose the unifying element is that all the stock comes directly from my scrap pile.

As I've posted about Shaker tables in the past, I'll review the highlights in two posts.  And remember, I'm always up for questions or discussion about the techniques.

The base begins with a turned column.  I've found that these can be glued up from leftover stock with great success.  If I use Titebond II Dark Wood Glue and try to keep the grain running in the same direction on each piece, I've never been able to see any difference between this and solid stock.  The design is simple, which just about matches my skills at the lathe.  The only hard number that I need to hit is the diameter of the top tenon that will join with the top -- and even this just needs to match a Forstner bit in my collection.  The bottom is turned with a slightly narrower diameter, the length of which matches the top of the leg.  This creates a base ridge that is the stop for the leg as it sits in its sliding dovetail.

Without removing the column from the lathe, I set up my sliding dovetail jig on the lathe bed.  I now mark the stops in the indexing head to allow me to make three cuts, dead center, at 120 degree intervals.  The first step is to create a flat spot upon which the leg will rest.  Structurally, this doesn't matter, but aesthetically it makes for a better join between leg and column.

Through trial and error, I know that I should first cut a 3/8" groove to a depth of 1/2" in a series of passes in these three places.  I follow this with one pass (at a depth of 1/2") with my 5/8" by 14 degree dovetail bit to achieve a perfect sliding dovetail mortise.

When this is complete, remove the column from the lathe and place the dovetail bit in the router table.

I've redesigned, slightly, the shape and size of the cyma-curved leg that is part of the beauty of the Shaker table.  The top is larger on this table than on previous iterations, so I've expanded the spread of each leg and reduced a bit of the bulk from my last design.  I do this by means of a pair of flexible bending sticks.  An initial drawing is made on my plywood template, small blocks are hot glued to the lines at intervals, and then the sticks are clamped to these blocks and manipulated to create fair curves.  I trace this and cut the template close to the lines.  Finally I hot-glue thin (1/16") strips of hardwood to the template edges -- ensuring a fair, bump-free, routing template.  It is important to make this template longer than the actual piece so that you can begin and end your routing without encountering end-grain.

Stock preparation for the legs has a bit of a twist as well.  Once the board is planed to the desired thickness, I cut it into leg-sized lengths with a cut that is at a 30 degree angle.  This allows me to line the tenon up along this cut line and keep the grain running along the long axis.  I trace each leg onto the stock, but I do not cut it to shape yet.  This allows me to machine the tenon at the router table with a wide bearing surface.

As usual, you use a piece of spare sock to dial in the thickness and depth of the sliding dovetail tenon.  This is a very sensitive part of the build -- one or two mm can be the difference between a good fit and firewood.  I like to err on the too-tight side and take a couple of passes with 220 sandpaper to get perfection.  I also strike a line with a cutting gauge along this cut.  At this angle, and with walnut in particular, you will get tear-out unless you take this precaution.

Only now do I take it first to the band saw, and then back to the router table to bring it to final dimension.

I trim the top and bottom of the tenon and round the top portion to match the round mortise of the column.  The actual stop for the mortise is the flat top of the exposed leg above the tenon.  These should be trimmed to the same length, and to the thickness of the base ridge to achieve a good fit.  Now all that is left to do is put together your first trial fit.

I'll wrap this up with one more post about fashioning the top and applying the finish, as well as a wrap of the Hammer-Beam Tables.  Cheers

Thursday, December 15, 2011

Workshop Tips You may Already Know -- Installing Metal Threaded Inserts, Correctly!

Recently, I was searching the web for something or other, (a video of a porcupine who likes corn? a Lance Link: Secret Chimp lunchbox?) and I came across this video.  At first I thought it would be about as useful as the instructions on a bar of soap.  I mean, C'mon how hard is this?  Sometimes the screwdriver breaks the top while you are bearing down, and they always seem a little tight, but this is intuitive, right?

I use threaded inserts when I attach table tops to their base, (this is called foreshadowing) and they look good when they don't snap in half.  Which for me, is too frequently.

Well, the tagline that shouted "YOU MAY BE DOING THIS INCORRECTLY!" drew me in -- and sure enough, I had been doing it incorrectly.  The video explains the correct technique much better than I could, and armed with this new knowledge, I sheepishly gave it a shot.  I'm happy to report that, indeed, that is not a screwdriver slot on top and that the drill press works a treat for providing even pressure while you turn the wrench.  Go figure.

So in case I'm not the last person to learn this, enjoy!  If I am, well, it won't be the first time I was a bit behind the times.  I'm still wounded by the experience of showing up on the first day of school with a Lance Link: Secret Chimp lunchbox and everybody else had switched to carrying their sandwiches in paper bags.

Friday, December 9, 2011

The Hammer Beam Low Table . . . Making Breadboard Ends

We're on the homestretch now, with the table flat, the base built, and the scent of TransTint is in the air.  I really enjoy making breadboard ends -- the process is very tactile and represents everything that is good about hand-made furniture.  As with most joinery, it helps me to start with a known dimension for the "mortise" element and then dial in the fit of the "tenon" element.

The thickness of the top is approx. 7/8" so I'm going to go with a tongue thickness of 3/8".  I will cut this groove, on visual center, on the breadboard end piece that is about 1/16" thicker than the top.  I say visual center as I just eyeball this on the router table.  Inevitably, one cheek is ever-so-slightly thicker than the other and I orient this on top to ensure that I cover the end grain of the table field.  I may be over-cautious in this regard, but coming up too thin on the top is an automatic reboot in the process.  I cut this to a depth of 1/2" on the router table.

Setting this aside, I begin to create the tenons on both ends of the table top.  I make a rough and ready jig that sandwiches the top between two pieces of plywood that creates identical fences on both sides of the board.  I measure back from the edge, with the bit in place so that it will cut a 1 1/8" tenon.  I then make a spacer block of this width that will align the jig to the correct distance from the edge every time.

I measure the width of the cheek on my mortised end piece with digital calipers, reduce it by a few mm, set this as the final depth of the router, and cut to completion in several passes.  I reduce it by that little bit to ensure that the end piece will stand proud of the table top.  With the dual fence in place, I flip the piece and rout the other side to within a few mm of completion.  Checking the actual fit with the end piece, I continue until there is a snug fit.

Now I make my story stick for the tongue. The tongue features three longer tenons that will be 1 1/8" in length -- adding the real stability to what is by nature an awkward cross-grain situation.  These tenons will be pinned with a dowel through the end, and depending on the orientation, the holes for the pins will be widened to allow for wood movement. I lay out the tenons symmetrically so that if it gets accidentally rotated 180 degrees between passes on the router table, the piece will still fit.

I mark the tenons and cut them out by hand.  From the tenons I mark the corresponding mortises on the end piece, adding approx. 1/4" on the two outer mortises to allow for seasonal movement.  I then return to the router table and "plunge cut" these mortises against the fence (I'm not detailing this procedure because I'm not sure if it is a good practice -- proceed at your own risk.)  A quick dry-fit lets me know that I am on track.

As you can see, I've cut the end boards slightly thick and overly long to allow for an exact fit.  My next step is to trim these ends, along with about 1/8" from each edge of the table top, to bring to the final dimension.  As my sled isn't large enough for this piece, I friction fit a spacer between the two end boards and run this edge along the table saw fence to the correct size.  Once one side is cut. it can run along the fence to cut its opposite number.

Using my 4 1/2 smoothing plane, complete with high-angle frog, I then plane the top of the end board to match the height of the table top.  I find that if I keep the end board attached to the top, pulled away by about 1/2", I can plane without the risk of making a cross-grain gouge, and monitor the fit with a square.  In practice, I leave the end board just fractionally proud.

 With the edges cut to fit and square, all that is left to do is to pin the end boards to the tenons with dowels in a manner that addresses the cross grain nature of this joint.  I find that a plunge router acts as portable drill press, positioning the hole very accurately and spinning the bit at a speed that discourages tear out.  While it might seem intuitive to use the edge of the end board as a reference for plunging these holes, I've found a method that I like better.  If you create a fence that is attached to the table top, you can drill the holes through the end board and tenons in one go, remove the end board, widen the two holes on the outside by about 3/8", without readjusting the fence.  This gives you a very clean channel for the dowel to ride in during the table top's seasonal journeys.

The best part of this is that you have already built the fence.

I start by marking the dead center of each tenon on my story stick and transferring this line to the end board. Using the jig I created to cut the tongue mortise, as well as the spacer block, I reset the dual fences in their original position relative to the ends of the tenons and clamp them down.  I dry fit the end board in place and add a 1/4" spacer strip to the fence. Why the spacer?

Using the jig without a spacer would place the bit dead center of the 1 1/8" original width.  Experience has taught me that this is too close to the short portion of the joint.  Pushing it out 1/4" places the hole completely in the long tenon portion of tongue.  This is better both functionally and aesthetically.  Now insert a 1/4" spiral bit and plunge through the three marked holes for the dowels.

Remove the end board, and expand the two outside holes to create a channel somewhere in the vicinity of 5/8" wide.  Now, the top is free to expand with the heat and humidity of summer, and contract in the winter dry spell.

The final step is to re-install the end board and peg with the dowels.  I place bit of glue only on the center tenon and reassemble. Using  a cotton swab, I coat the inside of the center hole with glue, dip the peg in glue, and drive it home.  The excess glue will fill any gaps created by slightly out-of-round dowels.  Reaching from underneath, I place a bit of glue in the outside holes, but only deep enough to coat the bottom cheek portion.  I drive a peg 3/4 of the way through, apply glue to the top of the dowel, and drive it home.  My objective is to keep any glue from traveling down to the tongue portion of the joint.  In all fairness, I'm not sure if excess glue would cause a problem, I just want to ensure that the joint will work properly.

After this cures for a few hours, I trim the dowel with a Japanese flush cutting saw, take a few passes with a block plane, and finally make a couple of passes with some 220 grit paper to make sure that I've removed any excess glue and to clean up any "bench rash."  be sure to take care when using the delicate flush-cutting saw on the white oak dowel.  I've read that this saw is not really designed to cut tough American hardwoods, so a light touch is important.

Several times along the way I used my smoothing plane to clean up the surfaces.  In a couple of spots I pulled out the shoulder plane to fine-tune the intersection of the end piece and the table top, and I finished the ends of the end board with a few passes on the shooting board.  All of this is intuitive, and you won't go too far wrong if you go with your gut on these decisions.

This turned into a much longer post than anticipated, and I'm sure that I've left something out.  Please feel free to shoot me a note i if you have any questions or see a better way to approach this most satisfying part of this project.  Cheers.

Next up:  Final construction and a bit of finish.

Saturday, December 3, 2011

The Hammer Beam Low Table . . . Flattening a Table Top with a Hybrid Approach

I often wonder whether my procedure for a given task is the "right" way to go about things. I suspect that I'm not alone in this feeling.  Woodworking magazines make it seem very arbitrary - creating a linear approach that gives consistently good results.  And that works well, up to a point.  On the other end of the spectrum is an approach that says "I'll let the wood be my teacher."  You experiment with a number of known techniques until the wood yields the outcome you desire -- and those techniques may vary given the wood species, your mood, the weather, and the application.

As a hybrid hand tool/machine woodworker, I'm comfortable moving forward with my preferred method (generally hand tools) but jumping ship the minute the going gets rough.  This is how I approach the all-important flattening of a table top.

It starts with two things:  a Number 12 Scraping Plane and an open mind.

That's not quite fair, it actually begins with a sense of what's possible and important during glue up.  I always orient my boards with the grain in one direction in order to keep the option of hand planing to completion in play.  This limits my design choices a bit, but I've not found that to be too onerous.  Depending on the species, whether I'm re-sawing, and my deadline, I machine-surface my stock over a series of days.  Hopefully I can keep any post-planing movement to a minimum.  I try to bring the machined thickness to somewhere around 1/16" above my goal, but I've not been in a situation where (within reason) final thickness was visually critical.

This is a five board glue-up, and I do it in two steps.  Perfection is the goal, but I've found that it is nearly impossible to fully correct any bend down the long dimension. You must keep checking the joints to see that they are even and use a straightedge across the boards ensure that they are not cupping.  I use bog standard pipe clamps since I find them easier to adjust than Jorgenson clamps.  My experience is that in spite of your best efforts, the wood will want to move to its own stasis point.  Forcing joints closed with too much pressure can result in instability down the road.  If things really start to go pear-shaped, I stop, scrape off the glue, and think about resurfacing/rejointing the boards.

My finished glue up (I'm doing two tables at once) looks like this.  It is not perfect, but it is within my own personal tolerances for quarter-sawn white oak.  For the record, I find QSWO to be prone to movement after cutting and surfacing, and sometimes balky to finish with a hand plane.

Once out of the clamps, I have a go at all the glue lines with a card scraper -- doing this while in the clamps and the glue is gelatinous is even better.

It has taken me a long time to understand fully the real difference between Flattening and Surfacing.  The first, Flattening, has much more to do with geometry (is it level, across all the boards, with no variations between each board.) It is a prerequisite for Surfacing which has to do with the texture of the flat surface.  In this case there are ridges on the boards, and in some places the variation is around 1/64" of an inch. I began flattening with my Number 12 scraper, equipped with a Hock blade. The blade is honed to a 45 degree angle (with no hook), and I lean it well forward.  Moving diagonally, but with the grain, I come from two directions -- creating a crosshatch pattern and removing stock at a pretty good rate.

I prefer scraping to planing with a jack plane.  In my experience a scraper will only dig as deep as the blade is set (in this case, the thickness of a paper towel) without any real risk of tear-out.  I'm sure that there could be a long discussion here about "type 1" or type 2" chips, toothing planes, and scrub planes -- I'd I'd like to explore that -- but this is what I know and it works for me.  I'm looking to create a uniform cross hatch pattern that touches all surfaces of the wood.

I also look at the quality of the scraping to make sure that it is fluffy and long (not chunky or just dust) and adjust the scraper accordingly.

Once I'm pretty sure that the high spots have been brought to the level of the low spots I remove the blade, hone it, and set it for a very light cut.  I now go with the grain and remove any ridges left by the diagonal scraping.  I have found that this is an important step, and can save a great deal of time when I begin surfacing.  Finally, I break out my 5 1/2 bench plane, set for a light cut, and begin first diagonal then straight passes with the grain.  I'm hoping that with this light cut I can plane with no tearout.

. . . And right away tear-out begins to appear on one board.  I quickly switch to my high angle 4 1/2, and though it is better, tear-out continues.  I even give my low-angle jack a try, but it is no better.  For the record, I have found that this light-colored, slightly stringy oak can be difficult to work.  Using a card scraper, I surface the wood to a depth below the tear-out.  I suspect that with ultra light cuts I could get the rest of the surface down to this level, but I'm not up for the task.

Breaking out the RO sander, I begin with 120 grit paper and in about 15 minutes have the surface completely finished to 220.  It could have been done more quickly if I could have found any 80 or 100 grit paper in my mare's nest of a sanding cabinet.  Was this my first choice? No.  Would I have preferred to finish this with my 4 1/2 plane?  Absolutely.  But I'm long past the idea of pursuing a course of action simply because I want to prove to myself (or the hand tool orthodoxy gods) that I can complete the task with style points intact.  I'm interested in making furniture, not making a point. Now all that is left to complete are the breadboard ends.

I'm curious to hear about your procedure for table tops and results and style points.  Cheers!