Difference between revisions of "CharliesProjects"

Revision as of 22:37, 6 April 2011

Strandbeest

We will make a 12-legged Jansen mechanism in a form factor more similar to a Chebyshev mechanism, which hopefully, we will be able to ride. Driving and steering mechanisms left aside, and gait also being considered much much later, we begin by building one leg.

Based on computer models{here}, the construction methodology takes advantage of the design's slicability. That is, linkages can be layered or stacked, with no possibility of collision between two linkages that are stacked on different layers. Cool. Easy.

After experimenting with beer cartons and Popsicle(tm) brand sticks, tinker-toys were the next choice, but I couldn't find any big enough. $65 of nutsnbolts and $???.?? of lumber went into the final version, as well as an entire futon. Thanks Joe! Your futon is the best! nva4gt:)

Using odd lengths of scrap 1x2, the first leg was born thusly:{pic here}

The next legs will be made with 6' and 8' lowe's crap lumber. someone should set up a web2.0 lumber drop shipper called lumbr.com -- hahaha. {pic of final build, painted, goes here}

IR Harp

I like this idea of Jenett's. Maybe we can do it with lasers [1] once we get the IR version working.

Printers to Mills

I have a number of canon printers (high quality stuff) to teardown, scrap, and salvage. The printers include steel rods, stepper motors, drivers, and other cool components. Is it enough stuff to make a RepRap? Let's find out.

Major components salvaged:

• High-polish precision steel rod, various lengths and diameters.
• 2xPower supply, 5/24VDC @ 1/1A
• 4-wire stepper motors. 24v, Bipolar, various steps/revolution
• QH4-4484 Mabuchi/Canon motor: 38mm long x 28mm dia, shaft 7mm x 2mm dia
  • 12v? 24v? W=VI?
• 34V 470- and 1000- uF capacitors
• Various driver chips: ULN2803A, L298HN+L6210, TB62202AF, A3953SB, M5266P
  • The ULN2803A is great for unipolar motors, where one side of the coil is always tied to the +V line
  • The L298HN+L6210 circuit makes a great dual full h-bridge. What's more, the L298 datasheet has a complete bipolar application circuit on p.8
  • The TB62202AF is also ideal for bipolar motors, but until the pcb mill is working, it would be quite a task to work with its small form factor.
  • The A3953SB is a full H-bridge, so two will drive a bipolar stepper. There was one in each of the i470d printers.
  • The M5266P is still under investigation. It has 4 outputs, so it can be used to drive a 4-coil unipolar motor, but can it be used to drive current forward and backward through a coil or two?

Testing power supplies and junk: i470d psu works as labeled canon bj-200 PSU: 1 G (white) 2 +24 3 G 4 +24 5 G 6+5

Stepper motor control

Using aforementioned driver chips, how do I make the motor move?

http://www.cs.uiowa.edu/~jones/step/index.html <-excellent

http://www.discovercircuits.com/S/stepper.htm

http://www.piclist.com/techref/piclist/jal/drivingbipolarsteppermotors.htm

http://www.8051projects.net/stepper-motor-interfacing/stepper-motor-connections.php

Construction of the mills

An order from SDP/SI, McMaster, and ebay later, we are ready to begin. The hardware is straightforward: We will use the bloominglabs bandsaw to cut some shapes out of wood for the body, but they will ave to be proportioned to the rods and leadscrews we are using.

We have many nice rods now, and 2 each of several lengths. approx. 14", 11", and 9", which will be used for the x, y and z axes respectively. That means the footprint of the mill will be 14x11" or so. The x table will be an bit shorter, to make up for the thickness of the material on the left and right sides supporting the y axis, so 10" perhaps, and half as long as the axis it rides on, so around 6 or 7 inches.

After brief discussion of fabrication methods, it's been informally decided to be informal about the construction, as any repeatability of our dimensions would require the same rods, and therefore perhaps the same printers.

TODO:

• drill matched holes in wood frame
• assemble spindle: collet, shaft, bushing, bearings, collar, tubing, motor
• mount rods and bearings in unassembled frame
• read and comprehend allegro 3953 motor driver datasheet
• assemble frame
  • x axis
  • y axis
  • z axis
• mount motors to assembled frame
• mount leadscrews to motors
• fabricate lead screw nut

Lathe

We can cast aluminum and have a drill press, so I'm pretty sure we can make a lathe somehow. More to come on this I hope.