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Author Topic: Abnormality (Exact stop vs constant velocity)  (Read 6520 times)

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Abnormality (Exact stop vs constant velocity)
« on: July 16, 2007, 02:44:18 PM »
Dear All

I have just purchased a tapping head which has a geared ratio of 1:1 (ie same feed going in as withdrawing). Tha manual recommends programming using G85. This works to a point except it chatters on the way out. The trouble shooting guide says the problem may be due to the fact process not using constant velocity mode. I have altered the general config file to cv mode but during the process it always reverts back to exact stop.

Does anyone have any ideas on what is controlling it?

Offline Whacko

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Re: Abnormality (Exact stop vs constant velocity)
« Reply #1 on: July 16, 2007, 03:48:29 PM »
After you changed the settings and clicked OK, go to the "view" menu and click "save layout". I had the same problem.

William
Nothing's impossible
Re: Abnormality (Exact stop vs constant velocity)
« Reply #2 on: July 17, 2007, 04:17:02 AM »
Thanks William
I'll give that ago today and let you know how I get on.
Cheers George
Re: Abnormality (Exact stop vs constant velocity)
« Reply #3 on: July 17, 2007, 11:47:48 AM »
Hi William,
Tried that but no change. as soon as the programe reaches either G81 or G85 it still knocks off cv mode.
The programe was created using lazycam as two drilling operation then manually editing the second from G81 to G85.
Will this have an effect?

Any thoughts anybody!!!!
Re: Abnormality (Exact stop vs constant velocity)
« Reply #4 on: July 17, 2007, 12:58:26 PM »
 ;D Hi george
sent you some g code created from Partmaster using G81 it works on my mach, first with drilling cycles, and then the tapping, at this point the cv light comes. on hope it works
Re: Abnormality (Exact stop vs constant velocity)
« Reply #5 on: July 17, 2007, 05:21:13 PM »
Hi Bob
yes that works on my system when I follow Williams suggestions, but it doesn't work at the drilling phase G81 (not that it matters for drilling) and the partmaster programe uses G01 for the tapping portion. I wonder if it has something to do with the canned cycles?

Has anyone else noticed the same?

vmax549

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Re: Abnormality (Exact stop vs constant velocity)
« Reply #6 on: July 18, 2007, 01:32:55 AM »
You do realize that a lot of tapping heads require a fast retract for .2-.4" to reverse the clutch properly. Without it the clutch can chatter as it is try to engage and thread at the same time. The drill / tapping cycles do NOT have the fast retract then resume  mode built in.

Not sure but the Canned cycle may be turning CV off.
 
Try programing a straight feed in then rapid up .2-.4 then resume feed out. I have mentioned to ART about the need for a Tapping head Cycle G84.1 .

Been there done that one, figured it out. (;-) TP
« Last Edit: July 18, 2007, 01:39:35 AM by vmax549 »
Re: Abnormality (Exact stop vs constant velocity)
« Reply #7 on: July 18, 2007, 05:14:22 AM »
Hi TP
The tapping head I have got is a Tapmatic SPD5 which doesn't have a clutch and has a gear ratio of 1:1 ie same feed out as in. I know what you are saying as the catalogue shows that alot of the clutch models have a ratio of 1:1.75 and withdraw at just under twice the speed. It was the Tapmatic instruction manual that recommended the use of G85 or G01
for control. I have found the G01 method works however I am new to the world of cnc and not very good at manual programming.I can't afford an expensive CAM package. Thats why Lazycam seemed like an answer to my prayers.

Cheers George

Offline ardor

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Re: Abnormality (Exact stop vs constant velocity)
« Reply #8 on: July 18, 2007, 07:11:10 PM »
1:1 tapping heads are not that hard to make.

I couldn't find one that was small enough in dia to fit into a cross tapping setup on my Wasino lathe.

An hour or two on an engine lathe and I had a tapping head with a Lyndex quick change tap holder and an OD of 1.25".

It has tapped 100,000+ holes so far.

Oh look there the little bugger is.

Could have made it shorter but that's what I needed.

Ashby
« Last Edit: July 18, 2007, 07:17:19 PM by ardor »
There is no approved dental use for WD40
Re: Abnormality (Exact stop vs constant velocity)
« Reply #9 on: July 19, 2007, 06:11:55 AM »
looks great Ashby, I'm impressed. I took a sneeky peek inside my unit then closed it up fast. waaaay too complicated for me.
Cheers George