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Author Topic: Looking for an experienced threading (G76) user's input.  (Read 4752 times)

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Looking for an experienced threading (G76) user's input.
« on: December 01, 2013, 09:09:48 AM »
I'm doing some threading lately and the G76 wizard does strange things at times.  I'm pretty sure it's me but was hoping someone that has used it often would share their settings with me.

Do the settings on this screen make any difference at all since they're all input in the wizard except for the cut & infeed types?  Do the different infeed types actually work?





Do these settings look reasonable?  I later found the chamfer settings are in degrees of rotation, not angle, correct?  Do the # of spring passes come at the end of the complete run or after each new cutting depth?





Does the minimum pass depth mean diameter when in the diameter mode or strictly radius in both modes?





Thanks for any any input anyone may have.  If putting on a head-dress, rattling bones, chanting & sprinkling white powder on the lathe will help; I'm OK with that too!
Milton from Tennessee ya'll.

Offline Hood

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Re: Looking for an experienced threading (G76) user's input.
« Reply #1 on: December 01, 2013, 01:09:16 PM »
The settings in the first pic will, I think, be used if they are not specified, and thus overridden , in your code.
The spring passes are at the end of the thread.
Yes chamfer is degrees, well assuming you dont have an ancient macro.
I would think depth per pass is depth of cut but would have to produce some code to see for sure.
As for the settings looking right, hell no, they look at least 25.4 times too small ;D

Hood

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Re: Looking for an experienced threading (G76) user's input.
« Reply #2 on: December 01, 2013, 01:12:20 PM »
BTW what version of Mach are you using?
Hood
Re: Looking for an experienced threading (G76) user's input.
« Reply #3 on: December 01, 2013, 02:33:13 PM »
I'm using v.057 which I think is supposed to be pretty solid...if Turn could ever be considered solid.;)

I hear you on the 25.4 times too small thing but even though you got me changed over to diameter mode, switching me to metric's going to be harder. ;D

I'm going to try some different settings later to see if it'll correct the wierdness I was getting last try.  It would make a normal looking cut with clean, shiny shavings peeling off then the next 4 or 5 passes weren't taking much at all then a deeper cut followed by the 4 or 5 nothing cuts thing again followed by the deeper cut, over & over again until the last deep pass which looked & sounded like it was too heavy.  It was acting like spring passes after each new cutting pass??  I was expecting to get a small but consistent removal of stock on each pass but it didn't happen.
Milton from Tennessee ya'll.

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Re: Looking for an experienced threading (G76) user's input.
« Reply #4 on: December 01, 2013, 02:44:18 PM »
I suppose it all depends on the size/rigidity of machine but I would normally be doing a start pass of 0.3 to 0.5mm and a min pass of 0.2mm, so that equates to 0.00118 - 0.00196 and  0.000787.

It is however a very long time since I have done any threading via the parallel port, then again I never had issues even back then. Only time I did have a problem was when I didnt have the sync mode option chosen in General Config and couldnt understand why things were going so bad ;D


Hood
Re: Looking for an experienced threading (G76) user's input.
« Reply #5 on: December 01, 2013, 04:45:38 PM »
OK thanks for the cutting info.  All going well I have Mon. off & plan to experiment some more.  I'm working on an ER40 chuck today.  I hope to get confident enough to cut the threads on it with Mach but 50 mm is pretty big.  Probably end up doing it on the manual lathe again!
Milton from Tennessee ya'll.

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Re: Looking for an experienced threading (G76) user's input.
« Reply #6 on: December 01, 2013, 05:15:04 PM »
Yes fair size for a small lathe.
Hood

Offline RICH

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Re: Looking for an experienced threading (G76) user's input.
« Reply #7 on: December 01, 2013, 08:02:32 PM »
Quote
Do the settings on this screen make any difference at all since they're all input in the wizard except for the cut & infeed types?  Do the different infeed types actually work
?

You may want to have a look at Threading On The Lathe which you will find in Member's Doc's.
Here is the link:
http://www.machsupport.com/forum/index.php/topic,13017.msg85313.html#msg85313

In reponse to your question on those settings you will find the followoing in the write up.
Yes they do work and you can do neat threading, like an acme thrad with just a requlare threading tool.
I will say that things will only be as good as YOUR lathe is.

The Turn cycle defaults provide default values when not specified / missing in G76.
 
Note the following settings: 
The cut type and infeed type settings will affect the Gcode posted by the wizards and the default is  “0”. You change them and use any combination of them  as follows:
 
Cut Type: defines  type of threading method 
0 - Flank cutting ( default )
1 - Alternate Flank cutting 
2 – Back Flank cutting
 
InFeed Type:  defines how the passes are calculated
0 – Constant volume threading ( default )
1 – Cut the thread in X number of passes  ( set in the wizard  DRO 1022 )
 
NOTE: THE ABOVE SETTINGS WILL DEFAULT BACK  TO “0” WHEN YOU EXIT MACH3 TURN. 

RICH