Machsupport Forum
Mach Discussion => General Mach Discussion => Topic started by: BIGWING on July 16, 2007, 02:44:18 PM
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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?
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After you changed the settings and clicked OK, go to the "view" menu and click "save layout". I had the same problem.
William
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Thanks William
I'll give that ago today and let you know how I get on.
Cheers George
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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!!!!
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;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
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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?
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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
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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
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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
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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
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BigWig, if the tapping head does a self reverse without having to stop and reverse the spindle then it has a clutch. Just a thought.
I tried to download the Manual on the spd5 but it was not available for download.
(;-) TP
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Hi TP
As far as I can tell there is no clutch with this model.
Certainly not the type that has spring loaded torque settings
on the top. When I work out how to attach a file I will post
a copy of the manual
Cheers George
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George,
G61 is exact stop mode and G64 is CV mode. Either of these will over-ride settings you have changed. Do you see any G61s in your code? Can you post the G-code for us to see?
Brett
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HI TP
Hopefully the SPD5 tapping manual is attached.
let me know what you think
Hi Brett
programe is at work so will post tomorrow
many thanks both for your help
Cheers George
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Hi Brett
Rather than waiting to tomorrow I decided to recreate the programe.
(a dummy prog of 4 holes drilled then tapped)
Don't worry about the speeds and feeds for tapping i am just going off
memory. The original were worked out using the formulae in the
tapping brochure. The operator instructions for the unit says the
tapping head must not be run in ramp or exact stop mode and at the
moment it is.
Many thanks for looking
Cheers George
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George the unit does have a clutch, just not the type you are thinking of. This unit has a very close clouple clutch arrangment that shifts from forward to reverse. It is "suppose" to run from a reamer cycle which is straight feed in and then out. But if you look at the 1st page top rh side under thru holes. It says to avoid excessive wear on the unit it is best to have a fast initial retract to reverse the unit for retraction. Those are the KEY words.
Also do you have a spindle RPM indicator to verify the actual spindle speed. The speed and feed have to be correct for the unit to operate correctly. If you plan to do a lot of tapping I would suggest you install an encoder to aloow you to see the true RPM. Also with the RPM dro workin you can USE feed per rev settings instead of inch per min. It makes the tapping programming very simple.
(;-) TP
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Hi TP
As far a I am aware there is a spindle encoder fitted.
On the mach screen I can see programmed rpm
then underneath the slightly flucuating actual rpm.
Now do I use this to good effect?
Cheers George