Low Cost CAM idea

Crazy idea for a low cost, highly accurate CAM system which can be made without precision tools.

The Inspiration

http://freeandeasy.sourceforge.net

Rough Sketch

Main Shaft:

Uses a long bolt, with a nut holding the head of the bolt to the base plate then a nut followed by a washer (small so it just covers the inner race) and then the bearing, then another small washer and a nut. Repeat that for the second bearing at the top... then between the two, there are large washers with a very large hole that clear the small washer and nut and those washers are drilled and screwed down to the top and bottom of the aluminum box tube. These will probably have to be 4 of the large washers, above and below each of the bearings. Perhaps the main wheel will go between two of these and be a press fit around the outside of the bearing.

Secondary Shaft

This shaft could be the same as the one above or it could use a rotary air joint in order to supply a vacuum vice in the second disk.

http://www.milllog.com/deublin.htm
http://www.tonymachinery.com/jointweb/productshowcase.htm
http://www.carymfg.com/pages/rotary.htm
http://www.carymfg.com/pages/rotary/main.htm
http://www.rotarysystems.com/index.htm

We have :

• Qty 4 Astrosyn Bipolar Stepper IBM P/N: 1408666 EC NO: T4906 23LQ-C202-G4V Minebea CO. Ltd (410-09) pulled from a Lexmark 4039 Optra
  • http://www.ni.com/devzone/advisors/motion/mineaba.htm

    Series	23LQ-C
    # of Models in Series	3
    Machine Type	H
    Size (mm)	N23
    Step Size (deg)	5.0
    Best Accuracy (arcmin)	15.0
    Cont. Holding Torque (N-cm)	22.6
    Rated Current / Phase (A)	1.0...2.0
    Nominal Voltage (VDC)	3.4...6.8

• Qty 1 Unipolar stepper pulled from an inkjet with pully and belt.
  • AstroSyn PN: EM-217 Type: 17PM-K041-P2F NO: T4Y24 (7.0/step?)

    Series	17PM-K
    # of Models in Series	10
    Machine Type	H
    Size (mm)	N17
    Step Size (deg)	1.8
    Best Accuracy (arcmin)	5.4
    Cont. Holding Torque (N-cm)	14.8
    Rated Current / Phase (A)	0.4...1.2
    Nominal Voltage (VDC)	3.0...10.0

  • 20 tooth pully
  • Belt MB5740 B4 K   04232    309 13 teeth per inch, 34" long.
    
    Using http://www.wmberg.com/Tools/BeltLength.html if the pully is .5 inches in diameter, the center line distance between the wheel and the pully will be 9.591"
    
    Using http://www.hoverhawk.com/bcalc.html with the same figures, the result is 10 and 21/64ths.
    
    Using http://www.csgnetwork.com/pulleybeltcalc.html with the same figures the result is 9.58
     
• Qty 1 stepper pulled from a dot matrix printer with pully and belt.
   
• Qty 6 Allegro A3972SB Dual DMOS Full-Bridge Microstepping PWM Motor Drivers
  • http://www.allegromicro.com/sf/3972/
     
• Qty 2 high power 16th microstepping controller kits from Roman Black
   
• Qty 8 608ZZ ABEC7 Predator Skate bearings from Sonic Bearing Co. 8mm ID.
  • http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=1856558827

We need:

• Qty 3 steppers for the second unit.
• Qty 4 Shafts (drill rod?)
  • http://www.harborfreight.com/cpi/ctaf/Displayitem.taf?itemnumber=42829
  • http://www.catalogs.google.com/catalogs?hl=en&lr=&ie=UTF-8&category=Business+to+Business&issue=6122&catpage=776
• Qty 2 Center support with two precision holes and motor supports (see picture below) Note: Mount motors offset left and right rather than one on top of the other (as in the picture) so that larger stock can be held on the top wheel without striking the top motor
  • http://www.engineeringfindings.com/cat22/cat22pg28.pdf
  • http://www.smallparts.com/HTML%20Product%20pages/zstt.htm
• Qty 4 wheels
• Qty 4 Belts
  • http://www.engineeringfindings.com/cat22/cat22pg267.pdf 1/5i Pitch
• Qty 4 Pulleys. Size to match stepper shaft and belt.
  • http://www.engineeringfindings.com/cat22/cat22pg266.pdf 1/4iID 1/5i Pitch.

See also:

• http://www.fullnet.com/u/tomg/gooteecn.htm Building Inexpensive CNC Machines

Questions:

• skyrianos@hotmail.com asks:

  Who is the author of this article? I need some info on "AstroSyn PN: EM-217 Type: 17PM-K041-P2F NO: T4Y24". Can he/she contact me? Thank you in advance

  James Newton replies: http://www.ni.com/devzone/advisors/motion/mineaba.htm Your unit (or at least its series) is listed there along with the specs.

Cutting the first wheel (or trying to) with a Dremel and a Roto-Zip bit clamped to the box tube arm. Lots of chatter with course bits and lots of clogging up with fine bits. My saber saw does better, and the rotary tool can then be used to clean up the cut.