Friday, April 29, 2016

Work On 26" Rip and Crosscut Saws

Since I'm between projects, it's a good time to get to some of the shop projects or maintenance tasks that have piled up.  I've been keeping a list of things that I'd like to do - as long as I can remember to write them down there's a chance that I'll actually do them.
The "To Do" List
Two of the items on the list are to fix the handle on the 4 1/3 TPI 26" Pax rip saw and to sharpen the 7 TPI Disston 26" crosscut saw.

I've had the Pax saw for a couple of years (bought new) and it's always had a small problem.  The handle moves a little while sawing.  I even exchanged it for another saw and the new one had the same problem, so I've lived with it.  The following two pics show how much movement there is.
I've drawn a red marker line on the plate along the curvature just below the bolts
Now after jiggling the handle, there's about 3/32" movement
I have another (totally crappy) saw that I shimmed the saw blots with pieces of an aluminum can to fix a similar problem and that worked fine.  But there is so much space between the saw bolts and the drilled holes that this won't work.  The bolt OD is 3/16" and the plate holes are 5/16".  The holes in the handle are slightly smaller at 19/64".
Piece of aluminum can wrapped around saw bolt as shim
My next choice is to get some nylon spacers and use them to shim the bolts.  The one in the picture below (that I had on hand) won't fit, so I'll look on McMaster-Carr for something (unless anyone else has an idea ...).
Nylon spacer shown with bolt and plate
So I've got to shelve this for now.

My other 26" saw is a Disston crosscut that I got at a garage sale.  It has needed sharpening for a while and I got to it today.  The first thing I did was to check the set.  The plate is about 0.040" thick at the teeth and the total set was about 0.054".  This was too much - I like to have about 20% greater measurement than the plate thickness, or 0.048".  So I set up my "anvil" - a heavy hammer clamped in the vise - and hammered the teeth (both sides) until the set was where I wanted it.
My "anvil"
Hammering the teeth lightly until the set was just right
Next up was to joint the tops of the teeth just enough to get a small flat on the top of each tooth.  I had made a little jointing jig for a standard file last year and it works great.
Jointing jig with file loaded.  Note the bolts that clamp the maple strip onto the file.
The next picture didn't come out as good as I wanted, but hopefully you can see the shiny flats on each tooth.
Shiny "flats" on tops of teeth
My indispensable tools for this process are shown next.  The magnifying goggles with head lamp are fantastic.  And before I upgraded my shop lighting I had purchased a small LED desk lamp.  Between the two of these I can actually see what's going on.  And you really need to see what's going on.
Magnifying goggles with LED headlight and freestanding cordless LED desk lamp
My saw vise is a homemade affair from plywood and strips of pine, clamped into my end vise.  The bottom is hinged.  The vise doesn't apply enough pressure, however, and you'll see in a later picture that I add a long-reach clamp to really clamp down in the middle of the saw vise.
Saw in the vise
I use a homemade rake and fleam angle jig while filing.  I don't remember where I first saw this jig, but it works fine.  Made from an approximately 1" x 3" x 3/4" piece of softwood.  The file is stuffed into a hole drilled in the edge and then one face of the file is lined up with a line drawn on the edge of the jig at the rake angle of 14°.
Rake and fleam jig
It's not accurate to align a face of the file to the rake line by eye, but if I hold a small ruler flat to the face it makes it much easier to tell if I'm close.
Aligning one face of the file with the rake line
The jig has a 20° angle at the end.  Actually the angle is 160° to the edge so that in use I file 20° off perpendicular to the saw teeth.  Lining up the 20° bevel of the jig with the saw plate does the trick. This picture is from over my shoulder.
Holding the jig level gets the rake, the 20° angle gets the fleam
After that it's just filing from heel to toe.  Some people say to go from toe to heel, but if I start at the heel I get in some "practice" with teeth that rarely touch wood and I get into a good rhythm by the time I get to the more used teeth.  My saw vise is not long enough to file the entire saw, so I need to adjust the saw in the vise to get the second half.
Filing away (see the long reach clamp in this photo?)
Here's halfway done.  Note the red marker has been removed on every other tooth and the flats that are still reflecting some light.
Halfway there
After turning the saw around and filing the other teeth I checked to see if all flats were removed.  Many were not and so I filed the teeth that needed more, focusing pressure forward or backward (rather than straight downward) to remove material where needed to get rid of the flats.  This way I don't remove more of a tooth that already had it's flat removed.

When I was satisfied, I took my coarse diamond stone and LIGHTLY rubbed it down the length of each side of the plate to even off the teeth and remove a bit of burr.
Evening off the teeth and removing burrs
A test cut felt pretty good in a 2" x 6" piece of Douglas fir.  I could tell a big difference from before sharpening.
The obligatory test cut
And the sawn surface looked pretty good.  I didn't get exactly to my lines, but at least the surface is relatively smooth.
The newly sawn surface
So I get to mark this item done on my list and hopefully I'll get some spacers to fit the rip saw handle holes and get that one off the list soon, too.

Thursday, April 28, 2016

Help!! I've Got A Scrap Problem

I'm experiencing post-project woodworking doldrums.  After finishing the chairs I'm having a tough time getting to something else.  You know what that means - it's time to clean up the shop.

I'm sure this is not true for anyone else out there, but I've got wood cut-offs everywhere.  Here's my benchtop with scrap from the dining chairs.  A lot of it is wedge-shaped from cutting the back legs.  Will I really ever do anything with it?
But that's not all ...
Here's more wedge shaped scrap on my saw bench:
A case of the wedgies
I keep a lot of smaller cutoffs in a milk crate under the bench for a fire next time we go camping.  Problem is I've already got another full crate and an overstuffed box in an outside closet.
More cutoffs!
This is in addition to a few areas in the shop where I've been storing shorter (but useable, honest!) scraps.  Here's some behind the bench.
More wood!!
And more - aaagh!  And note the plywood cutoffs between the shelves and the plastic bin unit.
And there are a couple more shelves that I didn't get pictures of that house small cutoffs.

A couple years ago I built an overhead storage area above where the garage door rolls up to.  I use that for longer stock, but as I'm sure you can guess, there are cutoffs up there, too.
Overhead lumber storage
I have two choices here - get rid of most of the shorts on Freecycle or Craigslist or keep them for that project that I'm sure will come along that will be perfect for them.

In a tiny shop, I guess you just have to bite the bullet and get rid of some stuff.  Time to do the deed.

Monday, April 25, 2016

Making a Sharpening Block for a Scrub Plane Iron - Resolution

Warning: this post may only be interesting to math geeks like myself.  I don't intend to to this often in my posts.  Only when I need to remember how I figured something out.

Recall that I wanted to figure out the radius of concave arc to shape a wooden block so that I can use it with sandpaper to sharpen a scrub plane iron that has an 8" radius.  If the iron was standing straight up (90° to the block), then an 8" radius on the block would be OK.
Iron at 90° angle to block
But since the iron will be sharpened at a 30° angle, an 8" radius on the block would not be the correct radius.
An 8" radius on the block does not match the iron when the iron is at 30° to the block.  Mind the gap!

Well, this has been rumbling around my brain for a few days and I finally came up with a solution today while on my bicycle.  Consider an 8" long plane iron with 8" radius on the business end.  In the following picture, the center of an 8" radius circle is the center of the back end of the iron.
Iron shown with 8" radius circle
Now draw two lines from center of the circle to the sides of the 2" wide iron at business end.  The segments are OA and OB.  Point "C" is along a straight line connecting A and B.
Closer picture of iron with lines OA and OB drawn (didn't really need to draw OB)
Since the blade is 2" wide, the distance between A and B is 2".  Point C is midway between A and B and so the distance between A and C is 1", as is the distance between C and B.
Close-up of the radiused end of the iron
I want to find the distance between points C and D.  That tells me how far the center of the blade extends past the sides of the blade.  Consider the right triangle OCA.  Since the radius of the circle is 8", the length of OA is 8" and the length of OD is 8".  Therefore, the length of OC is 8" minus the length of CD.

Angle OCA is a right angle, making triangle OCA a right triangle and the sum of the squares of the legs is equal to the square of the hypotenuse.

OC^2 + AC^2 = OA^2
(8 - CD)^2 + 1^2 = 8^2
8 - CD = SQRT(63)
CD = 8 - SQRT(63) = 0.063
Now consider the plane blade resting at a 30° angle on a 2" wide block of wood.  Pretend the edges of the blade (points A and B) are resting on the edges of the block, so that the center of the blade is protruding into the wood.  The question is: how deep vertically is the center of the blade.

Here is a cross section of that scenario.  This is a side view of the plane iron extending into the block.  This cross section shows the centerline of the block (lengthwise).
Cross section of center of block and iron
Not sure if this is clear enough.  But in this picture I want to figure out distance CE, which will tell me how big of an arc to cut into the block.  Triangle CDE is another right triangle and angle CDE is 30° since the horizontal dotted line is parallel to the block surface and the vertical dotted line is perpendicular to it.

With a little trig,
sin(30°) = CE / CD
0.5 = CE / 0.063
CE = 0.0314

OK, now that I know how deep vertically (into the block) the center of the iron is, I can figure out the radius of a circle that will give me and arc to match this depth.

Here is an end view of the block and I've drawn a new circle whose radius I need to figure out.  Let's call the center of this circle O'.  I've drawn a line from O' to one edge of the block (point A).
Block at bottom center looking end-on
Here's a close-up of the part that matters (center of circle is out of the picture).
Close-up of end-on view of block with arc from the circle that was drawn
The radius of the circle is O'A (distance from center O' to point A - the angled line in upper left goes to the center O').  This is the same as the distance from O' to E (also the radius of the circle).  Let's call that radius "z".  Since I want distance CE to be 0.0314, then O'C = z - 0.0314.

Triangle O'AC is a right triangle and by the Pythagorean theorem,

AC^2 + O'C^2 = O'A^2
1^2 + (z-0.0314)^2 = z^2
z^2 - 0.0628z + 0.0314^2 = z^2 - 1
z = 15.96 (I skipped a couple steps)

So call the radius that I need on the block 16".  With a concave arc having a radius of 16" scooped out of my block, I should be able to sharpen the blade whose edge has an 8" radius camber, when sharpening at 30° bevel angle.

As they used to say in geometry class: QED.

We now return you to our regular programming ...

Friday, April 22, 2016

Making a Sharpening Block for a Scrub Plane Iron

For a long time I've wanted to find a better way to sharpen my scrub plane blade.  I've been doing it by hand on the diamond stones, but I tend to change the radius to a MUCH tighter curve than intended.  My scrub plane is a Stanley #5.  I had filed an 8" radius on the business end of the blade and moved the frog back to open the mouth.  My thought was to create a block with a concave surface that I could use with sandpaper to sharpen the blade.
Rendition of the sharpening block with concave top surface
There is an error in my thinking here, but I'll get to that later.  I used my homemade large compass to draw an 8" radius on some cardboard from a cereal box and cut out the shape.
Homemade compass
Then I transferred the convex shape to the end of a squared-up block.  I'm making a convex block first so I can use it to more accurately form the concave block that I'll use for sharpening.  It's much easier to plane a block to a convex shape than to plane a concave shape.
Radius pencilled on block (view from above the block being held vertically in vise)
I planed carefully with the #4 and checked the progress with the cardboard template.
Not close enough
When it was close I used a thin scraper, bending it to task to smooth the shape.
A much better fit
Satisfied, I squared up a piece of wood for the concave block and pencilled in the radius I wanted to plane to.  I used my little wooden compass plane (correct name?) and checked the progress as I went.
Compass plane and scraper
Checking progress - pencil lines show where to remove more
When it was close enough, I bent the scraper to task and smoothed the surface.  But I was going to get the final shape using the convex block I made earlier.  Wrapping it in coarse sandpaper, I went at the concave block until I was satisfied with the shape.
Convex block wrapped in sandpaper
To sharpen the cambered iron, I put the concave block in the vise with some 180 grit sandpaper on it.
Ready to be used
The sandpaper wears out quickly, but it got the job done eventually.  I used the diamond plates to remove the burr and flatten the back, then put some leather with honing compound on the concave block to strop the blade.
Stropping the blade
This worked out quite well.  I did a test cut on some rough sawn stock and it seemed like it was much easier to scrub it than previously.  That was the success.  But here is the failure:
The blade had a tighter radius than the template
I didn't think hard enough about the radius that needed to be transferred to the sharpening blocks.  Look at this schematic I drew up in Sketchup.  Perfect match between the blade and the block of wood.
Blade with 8" radius standing vertically on block with matching curve in top surface
Close-up of above picture
Watch what happens when I angle the blade down so that it is 30° from horizontal.  In this picture, I've moved the blade to the end of the block.
See the gap?
And here is a view from the near end of the block looking straight down to the blade edge.
This view of the edge of the angled blade is the actual radius I should have put on the block
So the question is this: how do I calculate what radius to put on the block?  I have a degree in mathematics and I used to teach geometry (albeit 33 years ago), so I should be able to figure this out!

After trying different things in Sketchup, if I use a 16" radius on the end of the block, that would give just about the right curvature to match an 8" radius on the blade when it is angled at 30°.  Hate to use a brute force method here.  Sure would love a nice geometric solution.

Thursday, April 21, 2016

Dining Chair - Part 12 - Completion

Monday was a good day.  After not getting much done last week, it was great getting back to the shop.  I started off using steel wool to knock down the shellac finish on the second of the three chairs in progress and then waxed and polished it.
Love that shine
The steel wool creates so much steel dust, but I do like the feel of the chair better than after using sandpaper.

Next it was on to the seats.  I cut up the plywood and got it to fit in the space with about 1/16" clearance all around.
A nice fit
I used a crosscut handsaw to cut the plywood and that left ugly break-out on the back side.  But I knew I was going to round over the back edges to about 1/4" lines, so I didn't worry about it.
Starting the round-over
 The top edges were also rounded slightly.  I did  a test fit with the fabric in the seat space to make sure it would fit after upholstering, and that was a nice snug fit.  Then I bored the holes for air relief.
Holes bored for air escape
I love using the brace and bits.  These are 3/4" holes and the bit goes through the plywood like a hot knife through butter (OK, maybe refrigerated butter, but still ...).

Next up was the foam material.  I cut that to shape using the plywood as a guide.
Two inch thick foam
On the upper surface, I created a chamfer about 1".  Marked it out using a sharpie ...
Chamfer marked out
... and cut it using our kitchen knife (I got a "look" from the wife), which I had sharpened up on the diamond plates and oiled with the oil-soaked-rag-in-a-can.
It really helped to oil the knife blade
And here's how they look with the foam in place.  Things are really starting to take shape.
Chairs with foam
With these things taken care of , it was time for the upholstery.  When Karene got home, we laid out the fabric and marked out the seats with masking tape.
Three of four marked out
I had made the original chair last fall and used vinyl for the upholstery.  We decided to go with a different look, so that chair will get reupholstered.

I learned a little about sewing terminology and technique recently.  I was concerned about the fabric fraying after I cut it.  The lady at the fabric store said to use "pinking shears" to minimize fraying and fortunately my wife has a pair.
Pinking shears
My mother always had these (she used to make lots of her own clothes) and I thought they were just decorative.  Little did I know.  These worked great and the cutting began.
Zig-zag cutting pattern
Didn't get much done Tuesday, but Wednesday I got all the upholstering done.  I used the "Sellers" compression jig to press the plywood over the foam and fabric.  The jig is as long as my bench is deep, so I can clamp directly to the underside of the benchtop.
Compression jig in action
This really works great.  I clamped the jig until the 2" foam was compressed to about 7/8".  This will give nice tight upholstery when all is done.
Compressed foam
Stapling the fabric to the plywood is fairly straight forward until you get to the corners.  Sellers shows how to cut away some of the fabric and fold it to get a nice tight corner.
Corner #1 half done
It can be challenging to get the corners right, but with just a small amount of practice, it gets better.
Corner #4 complete and upholstery done
I'm using some staples that came with my old house - really - found them there.  These things are at lest 20 years old and probably a lot older.
I'm mumbling: "It's a Swingline.  It's my stapler."  (reference to Milton in "Office Space")

This box just barely lasted through this project, but just in case I got some more.  The new ones look a little different (cheaper), but fortunately the old ones lasted with just a few to spare.  Curious to see if the new ones were bogus, I tried out them out and they fit my stapler just fine and seemed to work good, too.
Bought this ~15 years ago for reupholstering chairs of an old dining table
Well, this project has finally come to an end.  I brought the chairs in and fit them at the table.
Out with the old ...
... and in with the new
Another view
And another
This project has taken over three months!  Damn I'm slow!  But getting faster and more confident with each project.  Thanks for reading.