AVR-Chat

Richard,

What kind of accuracy do you need?  Most machining operations will probably need more accuracy than a mouse engine will provide.  You'll also want something that is IP65 or better (sealed against dirt, oil etc) and that is very robust.  A readout that is inconsistent is worse than no readout at all!

I'd probably use an absolute position optical encoder.  We get ours from either PhotoCraft or CUI.  If you're only building one unit you can find one on Ebay for a lot less money.  You could use a incremental encoder as long as you can zero it out.  

Are you building just a readout or are you adding CNC to it?  If you're using a stepping motor you might get by with an open loop system and calculate the rotation since you know the number of steps taken.

  

Regards,


Tim Gilbert
JEM Innovation Inc.
303-926-9053 (office)
303-437-4342 (cell)
720-890-8582 (fax)
www.jeminnovation.com
www.pdksolutions.com


  ----- Original Message ----- 
  From: Richard 
  To: AVR-Chat@yahoogroups.com 
  Sent: Wednesday, December 03, 2008 9:48 AM
  Subject: [AVR-Chat] Re: Accelerometer question


  Talk about having the answer in the palm of your hand. I think the 
  mouse could give enough accuracy. I wanted to play around with an 
  accelerometer so I guess I was trying to make the problem fit the 
  solution. The project is to make a digital display for a rotary table 
  for my milling machine. For those not familier a rotary table sits on 
  the milling machine or lathe and allows you to cut at points around a 
  centre, cutting gears for example.

  There have been lots of interesting answers on this thread many 
  thanks and if there any other novel ideas I would love to hear them. 
  Rich

  --- In AVR-Chat@yahoogroups.com, "Rick" <eprom999@...> wrote:
  >
  > --- In AVR-Chat@yahoogroups.com, "David VanHorn" <microbrix@> wrote:
  > >
  > > the capactive sensors that they use in digital calipers look 
  pretty
  > good.
  > >
  > 
  > Yes good suggestion.
  > 
  > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  > Consider this-
  > Take apart a computer serial ball mouse. In there you will see two
  > optical breaker wheels, one for the X axia and the other Y. If your
  > mouse has a scroll wheel, you'll have a similar thing there. It
  > wouldn't take much imagination to adapt those parts to a Do It
  > Yourself inclinometer. The way these work is the mechanical wheel 
  is
  > spun and "chops" a beam of invisible infra-red light striking a
  > photo-transistor. It does so in a fashion which allow detection
  > circuitry to determine which direction the wheel is spinning too. 
  > Cannibalize a mouse for these components and build your inclinometer
  > from that.
  > 
  > If you are designing a product to market as an inclinometer look at
  > these sensors:
  > 
  > http://www.spectronsensors.com/tilt.html
  > 
  > They are capacitive.
  > 
  > M5
  >



   

[Non-text portions of this message have been removed]