Calculator Updates

Some Calculator updates:

I’ve finished an ANSI Chain Calculator; you’ll find it in the main index.  It calculates the following:

  • Physical properties of standard ANSI chains (multi-strands too),
  • Pitch length to inch length converter
  • Estimated chain elongation calculation
  • Estimated chain weight per length of selected chain
  • Center-to-center calculators for a two-sprocket system, calculating by sprocket centers or by chain length
  • Sprocket properties for the selected chain size, including pitch diameter, outside diameter, and tooth width.

The Fleet Angle calculator now calculates by offset, angle, and distance.  Change any one variable and the other two update. I’ve also added a diagram.

The Frustum Flattener was updated, the new navigation bar wasn’t working correctly.

The Resultant Force calculator code was updated; it would sometimes fail to re-calculate when changed.

Note that I’ve moved the the diagrams.  They used to be located below the calculators (akk).  I’ve moved them into a pop-up dialogue that you can load by clicking the “Diagram” button, as shown below…


Littlest Track Dog – The Real Thing

These are the finished pictures from the tiny track dog project. (Man, that was a long time ago.)  And the results were: success!  They worked like a charm.  There was no cable slip, no binding in the track, and the travel noise was minimal.  We noticed that the UHMW bowed (approx 1/32″) at the bottom when the cable was tightened down, which was expected from such small bits of hardware.  Nick simply pre-tightened the cable, and carefully shaved the dogs on the tablesaw — done.

The track was shaped from composite lumber (Home Despot decking).  It ended up cheaper than the equivalent amount of UHMW, slicker (& quieter) than lumber and was less fiddly than strips of maso or arboron.  It was also much gentler on our blades & cut mucho quicker than UHMW would have.

Littlest Track Dog (mark II)

This is the mark II design for the tiny track dog I posted earlier.   This version features a sandwich style construction, which has several benefits over the mark I design.

Littlest Track Dog (mark II)

Securing the aircraft cable through this dog should be vastly easier than the first version.  It’s as simple as two set screws, a few copper inserts, and four flat head machine screws.  Machining the cable path in the first version wasn’t too hard, but cleaning meeting two small, blind holes 135 degrees apart did prove a challenge.  As a result, threading the cable through dog #1 was an exercise in aggravation, something I do not care to repeat.

You’ll notice the top part of the sandwich is steel, which allows us to weld the knife in place through a milled slot.  Since we’re still waiting on details of the tracking furniture, we can build the dog now and leave the knife design for later.  Also, dog #1 featured a removable knife, which is nifty, but seriously impractical at such a small size.

Speaking of size, this dog will be the same as the last one – 15/32″ x 3/4″ x 3 1/2″.

The shop should get one of these built within the next few weeks.  Perhaps I’ll find enough time to slink away from the office and do it myself.  In either case, I’ll post an update, and let you know if all my wishful thinking was for naught.

Littlest Dog Evar?

Is this the littlest track dog ever?  Perhaps.  Either way, it’s sooo cute!  This prototype track dog measures in at 3/4″ x 15/32″ x 3.5″ and is milled from a solid chunk of UHMW.  (Ignore the oily grime, its fresh off the bridgeport.) The 1/8″ aircraft cable is secured with two set screws in the opposite face of the dog.  I’m thinking the mark 2 will feature a sandwich style construction with a fixed knife.  Stay tuned for later revisions to this project.little-dog

Laser Scissors!

A few weeks ago the ladies of the costume shop found the latest and greatest leap in scissor technology ever.  At some point during the laughter, they bought it and are now planning to use it’s terrible powers for theatre-wide domination.  Just be careful, you could put an eye out with that thing.


Stock Power Supplies… Revisited

Months ago I wrote a brief ditty about modifying commonly available computer power supplies to power low voltage DC effects.  You’ll find the original article here.  I wasn’t completely satisfied with the first one I modified.  You can see it in the picture below, it’s the ugly one to the left.  After perusing a Mouser catalogue this summer, I found what I was looking for – barrier strips with pass-thru terminals.  The ones seen below are made by Molex, specifically referred to as Solder Turret Style Terminal Blocks.  Catchy, isn’t it?  The Mouser part number for this specific model is 538-38720-3208.  They come in several different sizes, and I’m sure that other manufacturers make them as well.  Turns out the solder pins are just the right size to snugly fit female insulated spade connectors.  Super convenient, and pretty to boot!



P1020895You need small, ad hoc, weld-on bearings?  Check this out.  Use a plastic bushing, a shaft collar and a cone-point socket set screw.  Weld the shaft collar over a hole, and keep the plastic bushing in place with the set screw (the cone point is key).  Feel free to add a little threadlocker if you’re paranoid.  Works like a charm.


Flattening Cones

Update:  I just updated this frustum calculator with javascript versions that will run from the browser.  One will calculate the flattened frustum from the radii, the other uses the circumferences of the frustum shape.

Have you ever wanted to lay out the frustum of a cone on a flat surface?”
“A what?”
“A frustum, the part of a cone that is left when you lop off the top.”
Oh, yeah. If I had a nickel… sadly, I’m still poor.

It can be a little intimidating if you’re not familiar with the concept of how to go about it. Our draper came to me wondering how she could accurately lay out a dress based on an actor’s measurements. (Apparently the traditional layout method wastes fabric.) So I came up with this simple excel sheet that does the calculations based on the following measurements: waist (small circumference), hem (large circumference) & inseam (height of the frustum.) It gives back the details needed to lay the cone frustum out on a flat surface. The diagram below gives the general gist of what’s what. There is a larger version of the image in the excel document.

From fabric to sheet goods, I hope this calculator finds some use.

Update: There is a great description of how to flatten a frustum in AutoCAD over at Woodweb.