Cheap MPG for CNC using optical mouse center encoder

[abasir]

I'm in a process of building a MPG pendant for Mach3. Not willing to pay high price for the industrial encoder, I crack open an optical mouse and found that the center wheel encoder can be easily interfaced to the parallel port to provide the quadrature signals for Mach3.

It's a 3-pin encoder (not optical) that can be used directly with just 2 10k pull up resistors. More details here http://www.9w2bsr.com/2008_01_01_archive.html

[blackbeard52]

Very interesting. Good post and I would like to see more.

Bob

[phomann]

Originally Posted by abasir I'm in a process of building a MPG pendant for Mach3. Not willing to pay high price for the industrial encoder, I crack open an optical mouse and found that the center wheel encoder can be easily interfaced to the parallel port to provide the quadrature signals for Mach3. It's a 3-pin encoder (not optical) that can be used directly with just 2 10k pull up resistors. More details here http://www.9w2bsr.com/2008_01_01_archive.html

No wanting to dampen your enthusiasm, Not all MPGs have to be expensive. Have a look at;

http://homanndesigns.com/store/index...products_id=30

Cheers,

Peter.

[blackbeard52]

Maybe I missed something..... that encoder costs $65....his would cost $5....

B

[Khalid]

good work pls involve us in ur build...

[chich2]

Excellent!!!
Great work! I will be following this thread with great interest.

Is it dificult to use the optical pickups out a mouse? I could easily make a wheel with 100 slots in it so is there any reason a circut couldn't be made to use the optical pickups out of a mouse?

Chich

[vger]

I've got an idea for an MPG. You could print a "clock disk" on transparancy with a laser printer and use a couple of opto-interupters (even from a mouse) to read it. If you need a little stiffness you could sandwitch the clock disk between 2 thin pieces of plastic.

Opto-interupters are really easy to connect. Most of them are 3 wire, +5 v, ground, and output. The output is generally open collector and will go to ground when the light path is not interupted.

You could even make your own custom pulse count encoder.

Steve

[phomann]

Originally Posted by blackbeard52 Maybe I missed something..... that encoder costs $65....his would cost $5.... B

Ok, fair point. To some, $65.99 is expensive, to others it is cheap.

If you want to a cheap encoder have a look at these. less that $1.50, they are designed to be mounted into a PCB. They have a shaft to mount a knob on and have a built push-switch built in.

http://www.mouser.com/catalog/632/1394.pdf

Cheers,


peter.

[epineh]

Here is a link to a handy little program called Encoder Designer, you enter what type of encoder you want to make (incremental or absolute) , the diameter and the CPR you want and it prints the wheel for you, may be of use with the mouse sensor's, I was going to try this, even printed out the transparancy wheel's but that is as far as I got, too many other projects need finishing first.

http://users.adelphia.net/~skbosko/Robot_top.htm

Russell.

[dertsap]

Originally Posted by abasir I'm in a process of building a MPG pendant for Mach3. Not willing to pay high price for the industrial encoder, I crack open an optical mouse and found that the center wheel encoder can be easily interfaced to the parallel port to provide the quadrature signals for Mach3. It's a 3-pin encoder (not optical) that can be used directly with just 2 10k pull up resistors. More details here http://www.9w2bsr.com/2008_01_01_archive.html

ive seen lots on the net of guys using the same idea for spinners for homemade arcade game controller
keep us posted

[abasir]

Wow... so many interest huh... My apology for this delayed response. Was on the beach last weekend so didn't managed to get anything done...

First, some comments...

1. Peter: I'm aware of the MPG at your site. Yes, the price is reasonable and within my reach. I will probably buy one later when I'm in need of real MPG. For now, I running a Sherline, I can live with DIY MPG for the moment. I enjoy tinkering with stuff for the learning process and knowledge, even though sometime I ended up buying the 'off-the-shelf' solution. :-)

2. Using opto interrupter from mouse: Tried that before. Real PITA trying to align it properly once you take it out from the PCB. Doing a DIY disc, regular opto interrupter, etc normally result in a larger unit than I want... ;-)

3. The unit from Mouser is nice. Farnell Malaysia is selling it for about USD8... :-(

My overall goal is to have a small unit so I could make a pendant that can be operated with one hand... Need the other hand for other thing... :-)

[abasir]

Here's the outcome... a pendant that can be operated single handed...
The 4 buttons are used as follows:
1. Axis toggle (X, Y, Z)
2. MPG mode toggle(velocity, step/velocity, single, multiple)
3. Step size toggle (1.0, 0.1, 0.01, 0.001, etc)
4. Yet to be assigned...

Overall, the pendant works as expected. The MPG isn't as smooth as industrial once but then it's only few cents... Also, the wheel is acrylic... almost no freewheeling... a metal wheel will be better...

More photos at my blog (www.9w2bsr.com)... easier to weave comments in between pictures...