Tuesday, May 26, 2020

COVID Isolation Project #14 PPE Tuesday AGAIN

COVID Isolation Project #14 PPE Tuesday AGAIN
I'm gearing up to produce a lot of face masks this week for the Illinois PPE Network. They gave me a lot of fabric to work with. To make some parts of the process easier I 3D-printed some pieces including a rotary cutter in Onshape (since all local sources were sold out even though they had blades). I worked up a simple design that I could 3D-print and assemble with parts I had on hand. (Rotary Blade Cutter).
I'm working on this project concurrently with my Tesla Coil upgrade.


Monday, May 25, 2020

COVID Isolation Project # 13 - Tesla Coil Upgrade


My Original big coil, "Old Sparky", needs a new high voltage capacitor. Since I do not have the cash to buy one I'm making another one. At a minimum it needs to handle 12kV. I definitely won't finish it today but when it is done it will likely result in 4' arc's off of this old spark gap coil. First pic is the old capacitor, next is the supplies for the new on, spark gap for coil, power supply (outputs 6kV peak to peak), voltage doubler (increases it to 12kV), variac to control input voltage and finally Old Sparky. I'll post video when it's working at full capacity again (hopefully by this weekend).






Friday, May 1, 2020

COVID Isolation Project #3- A Better Portable Harmonograph


What is a Harmonograph? It is much simpler to show what it does than explain the math and theory behind what it does so here is my current design in action:

Some drawing examples:

I've used a Harmonograph for outreaches and community activities in the past but the one we use is awkward to transport and had a rather large footprint (the width is greater than many standard tables – still works great though). For a long time I’ve wanted to design sleeker version that is easier to transport but performs just as well, if not better than our larger, heavier version (it’s a work horse and has worked for many years and stood up to a great deal of punishment).
My goals for this more portable Harmonograph are as follows:
  • Made from easily sourced parts (making potential repairs much easier – nothing exotic in its design)
  • Easily portable – fold up into a flat form (ideally into a flat box)
  • Magnetic Drawing Platform to easily secure paper (no tape needed)
  • Sturdy – difficult to damage (stands up to eager children)
  • Safety features
  • Carrying case should be a "Grab and Go" (no need to take additional supplies)
  • Carrying Case will hold:
      • paper
      • colored pencils (lighter weight, less expensive and do not dry out)
      • pencil sharpener 
        • I found that colored pencils needed to much pressure (meaning increased friction and drag and shorter toal swing time).  Returning to pens
      • extra parts and tools (if needed)
      • Simple diagrams for setup (affixed to the inside of the case)
My current design utilizes a single piece of 3/4” conduit bent into the shape of a “U”. The base is made up of 4” x 1” lumber. This prototype does not fold up but the dimensions are set up to allow it once all other design features have been met.
The current drawing platform is made up of plywood and sheet metal (magnetic) and is sized to fit standard 8.5” x 11” paper including the magnets holding the paper down.
My initial pen/pencil holder was a spring loaded one that held the drawing instrument vertically above the board.  It ended up not working well.  The spring load mechanism would get stuck at random times.  It's possible that if it was machined on a lathe it may have worked out (though that might make it to delicate). 
My next pen/pencil holder design was a simple swing arm holder. In testing it proved too wobbly and resulted in poor drawing and increased friction (it only drew a few lines). In a much earlier trial (2 years ago) I used a more precise swing arm design that worked great but it was much to delicate (good lab design but not a good practical design).
I’m now attempting a more engineered design, stabilizing the swing arm with the addition of bearings, etc. My current prototype is not very elegant but I’m keeping my fingers crossed that this design will function better than the last one.
Making something new is always an iterative process. As long as you can learn something new from a design that fails to perform then you are making progress.
This design is definitely a work in progress but it’s getting closer every day to meeting my design goals. Once I get it to how I want it functioning then I’ll have to actually make the box for transporting it (another adventure in design… that I look forward to).
What I've discovered so far:
  • need a heavier drawing platform to increase momentum (resulting in longer swing time)
  • enlarge the drawing platform, possibly making it square to allow different orientation of the paper.
  • I would like to add a method to adjust the length of the x or y axis pendulum motion to allow other figures to be drawn

Monday, April 27, 2020

COVID Isolation Project #2 - Short Shop Stools


Another simple woodworking project using basic tools.  I needed a few short stools so that I wouldn't have to kneel on the floor of my garage.

The stool dimensions are:
Top 12" x 5"
Sides 15" x 5"
I did place a central support in each stool that's 11" x 5"
Everything was glued prior to nailing (I don't have compressed air).
After gluing, nailing (I did use a punch to drive them below the surface) and sanding I applied 3 coats of Polyurethane (brushed on).

Supplies:
  • 1/2" Baltic Birch Plywood
  • Wood Glue
  • Poylurethane
  • 1 1/4" 3D finish nails

Tools:
  • Saw (I used a circular saw with a homemade guide track) but a hand saw would do
  • Hammer
  • Clamps (I mainly used corner clamps)
  • Drill to make guide holes for the nails
So far they are very stable and handle a lot of weight.

COVID Isolation Project #1 - Plane and Chisel Sharpening Jig



Due to COVID-19 and Social Isolation, to stay busy I’ve been trying to finish up a slew of projects that have been on my mind and some that I started but haven't finished yet due to other more urgent issues.  Some of these are very practical, some are experimental, others are likely a little silly or just for building a certain skill (Learning by making).
My first project, which I completed over the weekend is a jig for sharpening hy hand planes and chisels.  It's one piece that holds my wet stone and stops for setting blades in the xxx for standard sharpening angles.  The base is Baltic Birch 1/2" plywood.  My goal was to keep the setup as compact as possible. I used 1/2" square dowels to surround and hold the wet stone in place, these were clamped and glued in place. After the glue was dry I applied multiple coats of Polyurethane just to minimize water damage to the wood from the wet stone (water resistant but not water proof).
After the multiple coats of Polyurethane were finished drying I screwed down the right angle aluminum extrusion pieces as end stops for the 25 and 30 degree angles for chisel and plane blades.
Supplies
  • 1/2” square dowel
  • Baltic birch 1/2” plywood
  • 1/2” right angle aluminum extrusion
  • 8 x #6 1/2” screws
  • Wood Glue
  • Polyurethane
 Tools
  • Saw
  • Screwdriver
  • Clamps 
  • Ruler
  • Right angle, 1-2-3 blocks or something else to align the blade stops