Hi, Jim

On My Compact 5 Lathe the index disk is about 4.5" in Dia. with about a 5/8 " slot to allow Mach to have time to see the opto Puls.

You may be able to use your Index pulse output as it is and add a IC555 Timer to reset with a adjustable time delay, R1 Var. resistor.

Edit: the resistor value is 1K and cap is 0.1 uf. This seemed to be the best values.

Just A Thought Hear, Chip

This one is working just fine 

Dave

Hears the pic I've been trying to attach.

Chip

Chip,
This thread works.
BTW I have that  same RS  book, bought it back in 42. 
RICH

I think first print was in 1941

Many thanks for this Chip

Here is my original message for those who may not have seen it -

Hi Chip,

In May 2007 you posted the message below on the forum and I've tried to download the IC555Timer.jpg file but with no success. Do you still have a copy you could post to me? I am in the process of converting a Compact 5 lathe to work with Mach and rather than cutting a wider slot for the index pulse I believe I can increase the pulse width electronically by using a 555 timer and your circuit may be just what I'm looking for. My plan would be to use the output pulse from a CNC4PC C3 board as input to your circuit Hope you can help.

Many thanks

Regards

Jim


Hi, Rick

On My Compact 5 Lathe the index disk is about 4.5" in Dia. with about a 5/8 " slot to allow Mach to have time to see the opto Puls.

You may be able to use your Index pulse output as it is and add a IC555 Timer to reset with a adjustable time delay, R1 Var. resistor.

Just A Thought Hear, Chip

--------------------------------------------------------------------------------
 IC555_Timer.JPG (171.97 KB - downloaded 130 times.)
 
« Last Edit: May 06, 2007, 12:56:59 AM by afn09556 » 

Jim
By all means reply back and let us know how things worked out for you.
RICH

To recap I asked Chip for a copy of his schematic so I could build a circuit which would deliver a constant pulse width to Mach regardless of the frequency of the pulse. My purpuse in wanting to do this was to use the original timing slot on my Boxford 125TCL rather than physically making the existing slot wider. It was also my intention to drive the timer circuit using the output from the CNC4PC C3 spindle speed board.

The plan was to use an NE555 timing chip but when I went to buy it from Maplins here in the UK they didn't have any in stock so I bought the CMOS equivalent (ICM755) instead. The ICM7555 is a plug in substitute for the NE555 but is more susceptible to static but uses less power and has faster internal switching. I also used a variable resistor in the circuit rather than the fixed 1K one recommended by Chip. I did this so I could dynamically increase (or decrease) the width of the pulse sent to Mach.

Mach needs a index pulse width of a minimum of 200 microseconds and I set the variable resistor to deliver a pulse width of about 600 microseconds and connected everything up to the XYlotex board I'm using in the lathe. I set Index Debounce to 0 (zero) and and tried it with and without Spindle Speed Averaging.

The results were fantastic even with these initial, which are now final, settings. The spindle speed shown, with averaging on, is rock steady from 60 RPM up to 2000 RPM, the max I can drive the spindle at present. Even with averaging off the results were equally impressive.

I have attached screen shots showing the two scenarios.

Incidently the cost of the components was less than 5GBP - do we need to get the board manufacturers to add such a capabilty to their portfolio?

Jim