Machsupport Forum

Mach Discussion => General Mach Discussion => Topic started by: Ian Hart on May 13, 2009, 03:18:25 PM

Title: Timing
Post by: Ian Hart on May 13, 2009, 03:18:25 PM

Help please,

Having installed a timing disc on my C1 style lathe, in accordance with the instructions in the Mach3 manual, I have a problem. I calculated the slot width according to the manual(3mm on a 99mm disc), I know it's right, the wife checked it. The software returns an accurate RPM for the spindle (exactly the same as my optical tachometer) up to about 200RPM. Beyond that, no increase in the registered speed. Any one any ideas as to what I should do?

Ian Hart

Title: Re: Timing
Post by: Hood on May 13, 2009, 03:41:25 PM

Increase the slot width to approx 10mm and it should work fine.
Hood

Title: Re: Timing
Post by: Ian Hart on May 13, 2009, 06:42:59 PM

Thanks

Isn't it a bit extreme when Mach3 says 3mm?

IanH

Title: Re: Timing
Post by: Hood on May 13, 2009, 07:18:41 PM

Just what I have always used and never had an issue, lathe goes to 2000 and mill to 5000 and both are rock steady.
Hood

Title: Re: Timing
Post by: RICH on May 13, 2009, 07:59:09 PM

Ianh,
Mach needs a pulse duration that is long enough to read, so, the faster you go the bigger the slot required relative to disc diameter.The electronics associated with it all has some time also. So I would consider what is in the manual a good ball park calc for the width.
Don't remember, had the same problem of reduced display at one time, but one of the versions cured the readout with no change in the slot width as per calc. This was for a single slot for index.

The four slotted timing disc i use has three small per calc and one twice as big and works fine.
I'm using Ver2.042.27 for the lathe FWIW.
RICH

Title: Re: Timing
Post by: Ian Hart on May 14, 2009, 03:56:54 AM

Thanks for the helpful responses, I'll try later.  Son arrived yesterday asking that I take him and wife for 'jolly' driving a Ferrari so today's playing in the workshop is out!

Ian H

Title: Re: Timing
Post by: hutchison on June 25, 2009, 06:12:15 PM

Quote from: Ian Hart on May 14, 2009, 03:56:54 AM

Thanks for the helpful responses, I'll try later.  Son arrived yesterday asking that I take him and wife for 'jolly' driving a Ferrari so today's playing in the workshop is out!

Ian H

hello, did you get anywhere further with this issue yet?

Title: Re: Timing
Post by: Ian Hart on June 26, 2009, 07:25:35 AM

Thanks for the continued interest.

I have increased the slot width to around 10mm and now it reads, still accurately, up to around 300rpm.

Should I create three small slots as well?  Mach3 says that it should work with just one.

IanH

Title: Re: Timing
Post by: Hood on June 26, 2009, 08:25:24 AM

What type of opto are you using?
Hood

Title: Re: Timing
Post by: Ian Hart on June 26, 2009, 12:10:15 PM

Hello again

The spec. sheet that I was given when 'friend' ordered the optoswitch is for a Honeywell HOA7720/7730 (Connectorized Transmissive Optoschmitt Sensor)

Ian Hart

Title: Re: Timing
Post by: Hood on June 26, 2009, 03:38:41 PM

Looks to be a decent enough opto, then again I know very little about this stuff ;D
 I use Optek OPB917B and no problems at all.
 One thing to check is that you dont have the Index debounce too high.
Hood