Astrolabe cases

Two sets of friends are getting married, and as both couples are intellectually curious, I thought an astrolabe would be a nice gift.  But astrolabes alone require some kind of protection... so I decided to make cases for them.

I started from a block of black walnut cut from a tree we had taken down earlier this year.  Since I had previously split it, the wood had been drying all summer in the back yard.

Mostly, the woodworking needed for the boxes was nothing particularly special.  The steps I did were:

1. Rough cut the block of wood into blocks, each about 2 inches larger than my intended final size.  I used a chainsaw for this, and did the work outside.
2. Power planed the blocks so that the edges were square and partially smooth.  Since my power planer makes an enormous mess, I also did this outside.  (The chips from the chainsaw and power planer go in my compost...)
3. Using a large hand crosscut saw, I sliced off the lids of the boxes.  This is a somewhat delicate operation -- even though it requires lots of force -- as you must ensure that the cut is perfectly planar and parallel to (at least one of) the faces of the block.  I don't have a large enough power saw blade, so this is also a manual step!  In all honesty, this is a ripping operation, so I should have used a rip saw... but I don't have one.  My crosscut saw works well enough.
4. I did an initial sanding of the cut surfaces and did a little bit of squaring up of the other faces.
5. I recessed the parts of the box that receive the astrolabe.  This involved tracing the outline of a (disassembled) astrolabe to where the recess needed to go on both the base and the lid of the box.  I then used a router in 1/16" depth increments to cut the recess.  For the base, the recess is stepped since the thumb ring is supported in a more shallow recess than the rest of the astrolabe.  This also gives room for the pointers.  I also recessed the lid.
6. Power belt sanding.  Lots of it!  Starting with 60 grit, I got all faces parallel and square and cleaned off all the cut marks from the saws and planes.  I also rounded the edges where I wanted them round.  Then I repeated the whole process  with 80, 100, 150, and 180 grit.
7. Since I wanted a very fine finish, I then hand sanded the entire box with 220, 320, and 400 grit sandpaper.  Walnut will polish nicely with finer sandpaper if you're planning for an oil finish, but that wasn't necessary for this project.
8. Five coats of polyurethane with plenty of time for drying, and 400 grit hand sanding between each coat.  I made sure that the recesses were left unfinished, since I wanted to adhere a velvet lining.

I wanted to line the inside of the boxes with velvet to protect the astrolabe.  Since the cast acrylic I have been using recently for astrolabes is actually fairly sturdy, a velvet-lined box is surely overkill.  (I did accidentally drop my larger astrolabe, and that shattered the thumb ring.  Since super glue is actually an acrylic, it was a simple matter to fix the crack.  Super glue leaves a mostly invisible joint on acrylic and bonds almost instantly.)

Velvet is a fairly troublesome material for lining.  To make it adhere to a flat surface inside the box, you must support it.  The usual way this is done is to glue the velvet to a sheet of cardboard first, and then glue the cardboard to the box.  Since velvet frays badly, you need to roll the velvet around the back of the cardboard (a second gluing) so that no cut edges show.  Finally, since the boxes have a circular cutout to fit the astrolabe, I had to figure out how to manage that joint.

In the end, I glued the cardboard to the velvet, rolled and glued the edges, but left the circular bottom edge alone.  After the glue dried, I hand stitched the circular bottom edges together.  The result was a stiff velvet "cup" that fits tightly inside the box.

Once the velvet was glued in place, I added hinges and a front clasp.  While hinges and clasps aren't difficult to install, they require precision.  You must be especially careful since you don't want to harm the finish.  I held the box in the vice, but lined it with soft paper towel so that the finish wasn't marred by the vice.  I sharpened (under a microscope) my 1/16" drill bit before starting.  To install the tacks for the clasp, I didn't strike the tacks with the hammer directly, but rather used a recessed punch to ensure that I didn't slip and damage the finish.  When setting the tacks, I also held them in brass tweezers. 

Fly for small tent (part 2)

Based on a guy line test fit, guying at the corners is mostly sufficient.

However, the long sides have a tendency to touch the side of the tent.  Adding guys at the middle of each of the long sides seems to resolve this issue.  The only subtlety is the door; the guy line should attach to the left side of the door zipper (when facing the tent) since I'm right-handed.

Parts needed

• 6 stakes
• 6 guy lines each about 2 feet long
• 4 corner attachments
• 2 side attachments for the long sides
• zipper pull

The top of the tent -- where all the seams come together -- is something of a mess.  To fix that, I sewed a rectangular patch at the top.

The six guy point attachments are made from siezed loops of 1/8" braided nylon cord.

These loops are sewn directly into the corners...

... the middle of the back ...

... and the left side of the zipper.

The zipper pull is a bit short, so I added a lanyard.  The lanyard starts as 2 feet of 1/8" nylon cord.

Here is the completed lanyard, which is tied directly onto the zipper pull.

Finally, I added guy lines and set the tent up.  Once up, I sealed the seams!

Fly for a small tent (parrt 1)

We have two small, inexpensive tents that we purchased years ago.  They're simple and easy to set up.  Best of all, they're very lightweight.

But sadly, the rain fly is way too small.  Since it seems that no really suitable tents are on the market, I set about making a replacement fly.

Based on some quick measurements of the tent, the basic idea is that there are four panels.  The front panel is split with a zipper.

The panels lay out on about 6 yards of fabric on a 60" wide roll.

Here's the bill of materials:

• 6 yd of ripstop waterproof nylon.  I'm using 1.1 oz weight, which should lead to about a total of 7 oz.
• 3 foot zipper
• seam sealer
• 4 peg tiedowns

First, I chalked out all of the pieces on the fabric to make sure that everything fit nicely.

The front panel (with the zipper) is handled first so that I can compensate for any issues with the front panel size.  The zipper seam is a little complicated.

I figure that if the overlap (v above) is more than three times the zipper half width (z above), it will be fit nicely.  This means that the seam allowance ought to be about 2 v + 1.5 z.  For my zipper, this was around 5 inches.

Here are the two panels to be zipped together.

Forming the pocket for the zipper.

Sewing the zipper into its pocket.

Completed seam.

The pocket folds over the zipper and is sewn in place.

Duplicated on the back as well.

The zipper doesn't open all the way to the top, so the front and back pockets are pinned together to close the front panels together.

Completed zipper pocket.

Since ripstop nylon is slippery stuff, each of the main seams is sewn in two steps.  (I was trying this seam as an alternative to the usual felled seam.  I did three of the main seams as below, and the last as a felled seam.  The felled seam was much easier, but perhaps wasn't as well aligned.)

First, the fabric is pinned...  (use lots of pins!  the fabric is quite prone to sliding!)

... stay-stitched flat...

... then folded, re-pinned, and final stitched.

Here is the tent with the fly at this point. 

The fly is a bit floppy, but this is not surprising.  Shaping still needs to be done, and guying is critical. The attachment points for the guys are determined experimentally with the tent pitched.

Still to come:

• Guy lines
• Stitch the bottom edge
• Shape the top
• Clean up loose thread ends
• Seal the seams
• Add a nice zipper pull

My "usual" pants hem

I almost always wear "formal" pants, since I don't find jeans comfortable.  Since I'm short, I usually have to hem my pants.  While a simple "straight" hem is functional, it is not quite as sturdy as I need for every day usage.  The visible seam isn't quite as nice, also.

Since I had to re-hem a suit some years ago, I took apart a more fancy hem on the pants and developed my own technique.  Ironing is crucial.  I set the iron on its maximum temperature, since I'm setting creases rather than merely taking out wrinkles.  Depending on the fabric, this requires some caution so that the fabric isn't damaged.  Since I prefer wool over other materials, this is rarely a problem, but wool-synthetic blends require a more light touch with the iron to set a crease.

Here is now what I usually do... 

My inseam is 25", so everything is referenced off of that.  I start by cutting the pants to somewhere between 28 1/2" and 29" (inseam plus 4"). 

Then I fold this in to 28" (inseam plus 3") and iron.  (I don't turn the pants inside-out, so the picture below is of the outside of the pants along the inseam.  The extra fabric you see from 28" to 28 1/4" is the inside of the other side of the same pant leg.)

I machine stitch this edge.  Thread color does not matter, since it will be hidden.

I bury the bitter ends of the thread on the inside of the seam, so they can't catch on anything.

Then I iron another crease, now at 26" (inseam plus 1").

And before any further stitching, I fold and iron at 25" (the final inseam).  This almost always requires several passes of the iron since there are many layers of fabric to crease.

At this point, the hem needs to be anchored with a stitch.  But since I don't want the thread to show through the outer layer, I don't stitch this with the machine.  So I hand stitch through all layers but the outer layer.

Here is the view from the inside of the pants...

... you can see no thread on the outside ...

... the stitching holds together here.

Here is the finished product.