Archive for September, 2014

Notes on the Roubo Bookstand

A Roubo Bookstand is made from a single piece of wood. It opens as pictured or folds flat. The design is actually much older than Andre Roubo (he wrote in the 1770s), it is a traditional form for supporting the family Quran.  Searching the Internet for “Roubo Bookstand” will keep you busy for many hours.

Here is plate 331 from Roubo’s book.

Plate331

Plate 331 from “L’Art Du Menuisier”

The project is based on a “Woodwright’s Shop” episode from season 31, 2011-2012. Many thanks and credit go to Roy Underhill. You can view it here or here  and you should to fully understand the material in this post as I won’t show steps here that duplicate Roys.  There is a downloadable plan here which references an almost identical book stand in episode 2205 which aired in 2002. The PDF plan differs only from the more recent show only in the shape of the hinge pockets. A much earlier episode, 1986 Season 06 ep. 3 has an example similar to the plan, using straight cuts for the hinge pockets, also see Season 20, ep. 5.  Woodwright’s DVDs are no longer available, but you can view them with the Popular Woodworking streaming service.

I’ve made this my hand tool project for 2014 and done several in soft wood for practice. In this web page I document methods and tools, especially where they differ from Roy’s.

I used construction grade 2x4s or 2x6s for practice pieces. The 2×6 version makes a fine Roubo IPad stand, the 2×4 size makes a dandy Roubo stand for a cell phone.

Roubo Tablet Stand

2×6 version Roubo Tablet Stand

Roubo Book Stand

2×6 version with a 7 inch tablet in place

I use this stand every week watching “Ask an Engineer”.

2x6 Stand with Nine Inch tablet

2×6 Stand with Nine Inch Tablet

I don’t own a smart phone but I borrowed one for this photo of the 2×4 version.

2x4 Roubo Cell Phone Stand

2×4 Roubo Cell Phone Stand

In the the next picture you can see two modifications I made to Roy’s plan. Both changes make the stand sit more upright making reading easier, and less likely to tip over. I shorten the front feet about 25%, and also inset the hinge pockets a bit, 3/32″ on this one inch thick stock. That keeps the stand from opening to a full 90 degrees.

Roubo Bookstand

2×6 Roubo Ipad version

In this page, I’m making a pair of cell phone sized stands from a 14 inch piece of Red Oak.

The hinge pocket inset requires angling the chisel when chopping out the pockets. I draw layout lines tangent to the hinge barrel circle just as Roy shows in his video, then add lines inset 3/32″ towards the center line.  1/16″ pilot holes for starting the saw cuts that define the hinge barrels get drilled along the inset line, not on the tangent line.

Modified Layout

Hinge shoulder position is changed

Here I have drawn a line from the inset to the barrel tangent. The pocket must be chiseled out along this angle, about ten degrees.

Angled Cut Line

Angled Cut Line

With the hinge layout complete, the next step is to saw down between the individual barrels. I tried Roy’s modified hack saw blade but got poor results so I acquired a jewelers fret saw. The problem is, these saws have a fairly narrow throat so can’t be used here in the normal way. I had to turn the blade 90 degrees so the fret saw could be held sideways.  The nose fitting on this saw can be rotated a quarter turn, but the handle clamp is fixed. I found however, that I could clamp the blade in a sideways position.  If you look closely below, the blade teeth are pointing towards the top of the photo, not out.

90 degree fret saw

Modified fret saw

So now the fret saw can be used off the side of the work, though it still has to be carefully supported at both ends of the blade. There is enough range to cut hinges in the 2×4 or 2×6 version but I’ll have to get a bigger fret saw for larger stands.

In the photo below you can also see half inch deep cuts across the end grain to start the lengthwise ripping that ultimately separates the two parts of the stand. These initial cuts were done with a Tom Fidgen-esque kerfing plane.

Cutting Hinge Pocket Slots

Cutting Hinge Pocket Slots

This Red Oak example is laid out two up. A pair of bookstands will be cut from a single long board, Roy mentions Roubo’s writing on this in the Woodwright’s episode – “to avoid the great loss of wood”.  The two tall back sections are laid out overlapping and separated with a frame saw after removing part of the overlap.

My frame saw is a Craftsman originally intended as a wall decoration. I bid on it in a moment of weakness and seriously regretted when UPS dropped it off. The blade was coarse with way too much set. I have since changed to a nicer blade cut from an old rip saw, and made special blade supports to use with this project. At this stage I will saw down to about a half inch from the hinge layout, leaving enough wood to absorb the stress of chiseling hinge pockets.

Frame Saw in Use

Frame Saw in Use

You can see in the photo above that the frame is held at an angle so it’s behind, not directly over the cut. I have made steel blade supports and twisted them 15 degrees. The modified saw works well and produces a fairly clean, straight kerf with not too much effort, even in this hard wood.

Angled Frame Saw Blade Bracket

Angled Frame Saw Blade Bracket

The result after separating the pair of blanks and shortening the part that will form front legs.

Two Roubo Stands

Two Roubo Stands

I chose to lay out the top and bottom curves at this time. This can wait until the stand is officially open but is easier while the blank is still a solid block. I use three templates, one for the top curve, one for the rear foot ogee, and a shallower ogee for the shortened front foot.  The templates have half the desired curve. The vertical edge is aligned along the stands center line, half the curve drawn, then the template is flipped and the other half traced. Symmetry is assured. I added masking tape in this photo so I could draw with a Sharpie for the camera.

The top and rear leg profiles can be cut at this time with a coping saw but the front leg profile has to wait until the stand is fully open.  I’ll wait and cut them when I need a break from chiseling.

Ogee layout

Ogee layout

Chopping out the ten hinge pockets is done per Roy’s brute force method – firmer chisel, followed by paring chisel, followed by sharp knife.  The inset hinge shoulders mean there is less room for the chisel but it can be done. In the next photo I am using a small bevel gauge to help guide the chisel to the necessary 10 degree angle.

Chiseling hinge pockets

Chiseling hinge pockets

After all ten pockets are cut, the last half inch of the dividing wood must be removed. Roy called this “going flat” and he clamps the piece in an end vise. I only have an iron shoulder vise so that’s where it goes. I found clamping a pair of hardwood blocks at the hinge tangent line makes it easy to tell when to stop sawing.

Sawing the Final Half Inch

Sawing the Final Half Inch

After an hour and a half of tweaking, paring off spots that were binding it finally opens all the way. It helps to open it as far as it will go then hold the saw kerf  up to a strong light and look into the hinge pockets. You can see places that are not completely separated or are binding.  Don’t use force, the wood will splinter. Just work with it gently until both parts are moving independently.

In this photo you can see another Secret Weapon. Utility knife blade that have the corners cut off. These are tough enough to be pounded into the hinge pocket with a ball peen hammer.

Finally Open

Finally Open

I’ve been cleaning up the saw marks with a low angle block plane or my trusty Stanley 5 1/4  followed by coarse sandpaper but on this hard Oak I used a card scraper after the plane. Because the stand doesn’t open to a full 90 degrees, planing these surfaces is hard on your knuckles.

When the stand is opened, it will sit on just the inside edges of the feet so its a good idea to bevel them.  It’s also a chance to tune the feet to eliminate any wobble.  My procedure is to clamp the stand upside down in the vise, then plane a few strokes on each corner with a slicing motion. The plane has to be long enough for the bed to rest on the opposite foot for reference, so I’m using the 5 1/4 in the next photo.  Check the stand often on a flat surface to see if you’ve eliminated all wobble.  For extra credit, tape a sheet of sandpaper to a flat surface and slide the stand across it a few times.

Beveling the Feet

Beveling the Feet

I like to stain Oak projects with Minwax Golden Oak. That will be followed by three coats of Watco Natural applied with my sandpaper spit shine technique, then paste wax.

First Finish Stain

First Finish Stain

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The Eleven Grooved Box – Tools Update

I have an improved fixture for making Eleven Grooved Box splines.  Roy Underhill’s video shows the spline blank placed in a grooved block. Then the blank is planed to size with a block plane.  The problem is, this eventually cuts some off the top surface of the grooved block causing the splines to come out too small. Then the splines won’t do their job well and look terrible.

My improved method has three secret weapons:

  1. A Kerfing Plane to make the blanks
  2. A modified Dado plane with skewed blade
  3. A sizing block with a channel to guide the modified plane

Secret Weapon #1

Tom Fidgen, in his book “Unplugged Woodshop” describes a kerfing plane. You can get parts to build one from Bad Axe Tool Works. Toms kerfing plane looks a lot like a stair saw with a fence, you can see it on his web site.  My version is made from a vintage plow plane and a blade cut from an old rip saw. It’s easy to cut  a tempered saw blade. Just score it on both sides with a Dremel grinder and cutoff wheel. Put the blade in a vise and flex it, it will break along the score line.  The next problem is drilling holes in the hardened blade. It will wreck a conventional twist bit, but I had good luck with carbide tipped masonry bits.  First, center punch the hole positions well, drill a pilot hole with a 1/8″ masonry bit, then finish with another masonry bit sized to fit your screws.  Use plenty of oil while drilling.

 

Kerfing Plane

Kerfing Plane

 

This old plow plane has an inch or so of the adjusting threads stripped so I added a spacer block to the fence to skip over the bad spot. The next photo shows the kerfing plane making 5/16 inch deep slots in the end grain of a Walnut scrap. The modified plane is accurate enough that I can easily slice four spline blanks from this 7/8″ thick bit of wood.

Kerfing plane in use

Kerfing plane in use

Now that three kerfs are cut, use a backsaw to cut the four spline blanks free. I kerfed both ends of the Walnut scrap while I was at it.

Cutting the spline blanks free

Cutting the spline blanks free

The end result after a bit of block planing to remove saw fuzz. Eight spline blanks ready to be trimmed to size.

Walnut splines

Batch of eight Walnut splines

Secret Weapon #2

I always had trouble using a block plane to trim the blanks. The plane would sometimes catch the blank and break it. Since these are planed across grain, then on end grain, the plane has to be held at a skewed angle. That makes it awkward and even easier to damage the sizing block.  I have a “vintage” 3/4 inch wide dado plane with a good skewed blade. That would do a nice job on the cross grain blank but would certainly tear up the sizing block. I thought about how a shooting board constrains the blade with the small bit of iron sole below the blade. A dado plane has a full width blade so that won’t work, but the solution I’m using adds outboard hardwood skates to the plane. These will stop the cut at the appropriate depth if I make a runway on the sizing block. The skates are made from a strip of Maple hardwood flooring sliced in half down the middle, then clamped onto the dado plane.

 

Modified Dado plane

Modified Dado plane

This photo is an end view of the modified plane. You can see at the bottom where the Maple has been thinned to 1/8″ on each side to form skates. Skate may not be the best term as these are used as guides and as a depth stop. They are adjusted to be even with the sole of the plane.

This outrigger skate technique would also work with a shoulder plane. Or you could make a wider sizing block and just use a block or smoothing plane, in which case you wouldn’t need the skates. The iron on either side of the blade would serve the purpose.

Modified Dado plane

Modified Dado plane

 Secret Weapon #3

For the modified plow plane to work, we need a sizing block that has a channel to guide and stop the skates. I made this on the table saw using a stacked dado blade set. The wood is from a backyard Apple tree, very hard. In this photo you can see the profile, wide channel for the plane on top and bottom, a groove for trimming thickness on the top, two grooves (with slightly different depths) for trimming width on the bottom. I cut the thickness groove a little too deep so it is shimmed with Post It note paper.

Spline sizing block

Spline sizing block

The other end of the sizing block has a stop screwed on. It’s removeable to make it easier to recut the grooves if necessary. Both ends are drilled to accept the stop. The sizing grooves are not centered so moving the stop to the other end from time to time will help even out wear on the dado plane blade.

Sizing block removable stop.

Sizing block removable stop.

Using the jig is a simple matter of clamping the block in the vise, inserting a blank in the groove and go to it.  Always plane the blank to proper 1/8″ thickness first and turn the blank over a couple of times so both sides are dressed. Here you can see how the channel in the sizing block is guiding the plane. The cut stops when the skates hit the bottom of the channel.

Thickness planing a spline blank

Thickness planing a spline blank

Coming out of the first step we have a blank evenly thicknessed to an eighth of an inch.  Also in this photo you can see the port sawn into the side of one maple skate to allow shavings to exit.

Spline planed to 1/8" width

Spline blank planed to 1/8″ width

The sizing block is now rotated in the vise so the quarter inch deep grooves are up. The thicknessed blank seats in one of the grooves where it can be trimmed to exactly a quarter inch width.

Width planing a spline blank

Width planing a spline blank

This final photo shows the completed cross grain spline accurately sized to 1/8″ thick and 1/4″ wide.

Finished splin

Finished spline

These three Secret Weapons work really well and make spline production easy.