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Author Topic: Progressive Pecking  (Read 622 times)
Bob La Londe
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« on: December 04, 2019, 20:39:04 pm »

Generally if the speed and feed is good when deep drilling you can peck 3X diameter on the first peck, 2X on the 2nd, 1x on the 3rd, and 1/2X on every peck thereafter.  Generally I am not quite that aggressive, but it seemed the other day when I set a secondary drill operation for the 1/2X deep pecking it started pecking at clearance height even though stock height was set at the depth left by a previous pecking operation. 

Does it make much difference?  No.  Not really.  Not if you are drilling a couple holes.  It makes a HUGE difference if you are pecking drilling 80 deep holes.  Worse if you have to peck those same 80 holes in multiple work pieces. 

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Garyhlucas
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« Reply #1 on: December 04, 2019, 23:48:23 pm »

I saw the same thing in trying to peck a 1” hole 4” deep in PVC using a forstner bit. I wound up just hand programming by cutting and pasting the first set of moves and changing the depths.

I would like an MOP that can do a chip breaker peck cycle instead of just a full retract. Used to use that a lot on an old Bandit control drilling aluminum to produce short chips that don’t wrap.
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Gary H. Lucas

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Bubba
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« Reply #2 on: December 05, 2019, 00:41:53 am »

I would like an MOP that can do a chip breaker peck cycle instead of just a full retract.
*************************
The same here, It don't need much, use peck depth and back out 5%. Yeah, I know is easy to say, but to code is a challenge I can only imagine.. Cheesy Grin Grin
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Dragonfly
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« Reply #3 on: December 05, 2019, 08:49:07 am »

... it started pecking at clearance height even though stock height was set at the depth left by a previous pecking operation. 

In CamBam 'Retract height' is the parameter controlling the peck start/retract height when 'Canned cycle' is selected.
Somewhat confusing when one starts using canned cycles.
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kvom
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« Reply #4 on: December 05, 2019, 12:25:10 pm »

G-wizard recommends 1x pecking for all holes where pecking is needed.  I've never had an issue using anything but that on deep holes.
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lloydsp
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« Reply #5 on: December 05, 2019, 13:22:41 pm »

Kvom,

That is what I use, also, for twist drills.  I've gone in deeper than the flutes on a few holes, without experiencing 'chip packing'.

I have to admit, though, that I've never drilled deeper than about 2x the tool diameter with a Forstner bit, so I don't know how they behave in really deep holes.

Lloyd
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Bob La Londe
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« Reply #6 on: December 05, 2019, 15:03:30 pm »

Gary & Bubba, 

I believe you guys are using Mach 3 on atleast one machine.  G73 does "fast peck drilling" that does not fully retract.  I am pretty sure its an old Fanuc standard and should be supported on multiple controls.  It does not do what I want, and for deep holes (past the flutes) it would be a bad idea, but it is the cycle you guys are looking for.  A chip breaking peck cycle rather than a chip clearing peck cycle. 

On your Mach 3 Screen you can just click the G-Codes button, scroll down and read it. 

There are a number of ways you could implement it, but the easiest might be a find replace using a text editor. 


* G73.jpg (365.78 KB, 1680x1050 - viewed 7 times.)
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Garyhlucas
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« Reply #7 on: December 05, 2019, 15:28:51 pm »

Bob,
Yes the G73 is what I want but I couldn't figure out how to get that as one of the options in the drilling MOP.  Is there a way to do that?
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Gary H. Lucas

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Bob La Londe
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« Reply #8 on: December 05, 2019, 15:42:58 pm »

Bob,
Yes the G73 is what I want but I couldn't figure out how to get that as one of the options in the drilling MOP.  Is there a way to do that?


I guess you could modify the post processor, but that might result in bad results elsewhere.  If I needed to use it right now I would probably just open the G-Code file in a text editor and search for G-drilling cycles and replace them as needed. 

There is a field in the drilling MOP to change/add some parameters and modify how a drill MOP operates, but I don't think you can change the primary G command there.  (Maybe you can, but I haven't played with it.)

I did use that parameters field for my TC tapping cycle, and then just saved it as a style so I don't have to remember it.  I have several styles for TC tapping.  I just changed the pitch (depth increment) to create a new one. 

Back on the original topic (sorta):
After reading this thread I read elsewhere a few places, and several people report good results with 1X diameter deep pecking.  For my application that would save me some considerable time.  I will try it today as I still need to cut a 4th insert with those same 80 deep 20X(+) holes.  I have some new name brand collets and new carbide drills so hopefully it will work.  I am looking for something I can do faster and reliably without having to replace a drill after every part. 

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Garyhlucas
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« Reply #9 on: December 05, 2019, 16:01:26 pm »

This is one of those places where a subroutine and variables is really useful.  You hand code the vertical motion and place it in a subroutine.  Then you program positions in another subroutine that calls the first one after each XY move  then calls the seond subroutine at each location.  I used to use this for tapped holes on the Fadals.  First subroutine was passed the second, third, four subroutine number in a variable.  First pass spot drilled/chamfered all the hole locations.  Second pass drilled the hole, third tapped the hole.  Once the spot drills ran while the operator was carefully checking the locations you were certain the others were going to hit the exact same spot.
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Gary H. Lucas

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Bob La Londe
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« Reply #10 on: December 05, 2019, 18:29:00 pm »

I think in your case a fairly modest rewrite to the Drill MOP by the developer to select between chip break G73 or chip clearance G83 pecking would be the optimum solution.  

It does not answer my need for a progressive pecking routine, or atleast an ability to start pecking at a stock height/depth setting. 
« Last Edit: December 05, 2019, 18:31:05 pm by Bob La Londe » Logged

Getting started on CNC?  In or passing through my area?
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Some Stuff I Make with CamBam
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Bob La Londe
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« Reply #11 on: December 05, 2019, 19:49:11 pm »

Bubba & Gary,

FAST CHIP BREAKER PECKING USING G73

I think you could do this:

Enter this line of data in the Custom Script field
G73 Z$z X$x Y$y Q$q F$f R$r

Select Custom Script as the drilling method.  

So you do not have to remember it in the future.
Copy the MOP.
Go to your styles menu in the system tab and create a new style in the correct style library.  
Right Click the Style and paste format.
Name the Style something easy to remember like "Chip Breaker Drilling" or "Fast Pecking."
Use that style when you want to fast peck drill.  

Please test before running, but a quick simulation on my desktop in a sandbox installation of Mach 3 shows it performing about how I would expect.  

The line of code using this method looks about like this:  G73 Z-1 X0 Y0 Q0.125 F10 R0.01

« Last Edit: December 05, 2019, 19:52:02 pm by Bob La Londe » Logged

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lloydsp
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« Reply #12 on: December 05, 2019, 20:28:16 pm »

And so, as a "request", we should request that the G73 peck drill cycle be added to the drill MOp options.  Yes?

Lloyd
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Bob La Londe
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« Reply #13 on: December 05, 2019, 21:01:49 pm »

And so, as a "request", we should request that the G73 peck drill cycle be added to the drill MOp options.  Yes?

Lloyd

We could, but it seems we can use any of the drill operation G-Codes by using the method I detailed above without any modification.  Gee, almost like the MOP had been developed with that in mind.  LOL. 

I still can't do decremental peck value peck drilling though. 
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lloydsp
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« Reply #14 on: December 05, 2019, 21:06:17 pm »

Would multiple G73s with progressively greater starting depth and progressively smaller peck lengths do it?

Could the multiples cycles be used in the same Custom Script?

Lloyd
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