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Author Topic: Peck Drilling....  (Read 12376 times)

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Re: Peck Drilling....
« Reply #10 on: December 27, 2009, 12:09:04 PM »
These are for lathe use. OK, I'll catch up - I'm still drilling vertically on a mill.

Thanks,
Bill C.
Re: Peck Drilling....
« Reply #11 on: December 27, 2009, 12:16:39 PM »
Are these macros developed by Hardinge of any help?
Nosmo.

Those are interesting.  I'm surprised by the aggressive start, but the rest is consistent with my understanding and experience.  I haven't had much luck with drilling 3 diameters in one pass on either small or large drills.  It works OK in the mid-range - perhaps 1/8-5/16 or so.

Regards,
Ray L.
Regards,
Ray L.
Re: Peck Drilling....
« Reply #12 on: December 27, 2009, 01:14:16 PM »
It works every time if you do it by accident!

Bill C.

Offline RICH

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Re: Peck Drilling....
« Reply #13 on: December 27, 2009, 04:15:56 PM »
Ray,
When are you going to post your macros and will they work on the lathe?
RICH
Re: Peck Drilling....
« Reply #14 on: December 27, 2009, 04:28:21 PM »
Ray,
When are you going to post your macros and will they work on the lathe?
RICH

Rich,

What I wrote is not Mach3 macros, but a G-code generator, written in Perl, that's part of the post-processor I wrote to optimize the G-code for my machine.  Unfortunately, there's no clean way to pass more than 3 arguments to a Mach3 VB macro (only P, Q, and R are accessible), and peck drilling requires more than 3 arguments.  I've asked Brian to fix this in v4, so we'll be able to have ALL arguments in macros (X-Z, A-C, S, F, P, I, J, R, Q, etc.).

Regards,
Ray L.
Regards,
Ray L.

Offline RICH

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Re: Peck Drilling....
« Reply #15 on: December 27, 2009, 04:57:44 PM »
If you find some good info on pecking remember to post it here. I didn't do a search and surely there is some good advice out there. What I did was tailor the parameters to mimic what worked when doing it manualy ,but then,
that was for real small holes. Learning never stops.
RICH
Re: Peck Drilling....
« Reply #16 on: December 28, 2009, 11:37:54 AM »
Melee,

I'm just using a lookup table.  Basically run full RPM and feed, and run a peck depth of one diameter, until 3 diameters, then reduce feed and peck depth by 10% and RPM by 5% for each additional diameter below that up to 6 diameters.  Seems to work OK, but it's had very little testing to date.  I found an Irwin drill spec sheet that suggested something similar.

I understand completely why you parsed the line as you did, and it was a very clever solution to an otherwise rather intractable problem.  I've just found such solutions tend to be rather fragile over time (that, and I can't think of worse language than VB to have to write a parser in....).  But, obviously, you had no choice here.  It was also what prodded me to ask Brian to make all arguments available, so a good thing will come from it for sure.  My solution was to just expand the G73 into G-code using a post-processor, for which I already had a working parser, so it was trivial to implement.

Regards,
Ray L.
Regards,
Ray L.
Re: Peck Drilling....
« Reply #17 on: December 31, 2009, 01:48:24 PM »
Hi again Ray,

I have written an amended version of my high speed pecking macro, which allows for variable pecking as the hole deepens, using your rule of thumb as per previous post.

A debug print of the internal lookup table it creates, shows the results when drilling a ridiculously deep hole with a 4.5mm drill in simulation

4.5mm drill  600 RPM  MaxPeck 4.5 MinPeck 1.5
Hole depth 51mm
Once either MinPeck is reached or 50% of original RPM, values are capped

Entry  0    Peck mm  4.5    Speed  600
Entry  1    Peck mm  4.5    Speed  600
Entry  2    Peck mm  4.5    Speed  600
Entry  3    Peck mm  4.05   Speed  570
Entry  4    Peck mm  3.64    Speed  541
Entry  5    Peck mm  3.28    Speed  513
Entry  6    Peck mm  2.95    Speed  487
Entry  7    Peck mm  2.65    Speed  462
Entry  8    Peck mm  2.39    Speed  438
Entry  9    Peck mm  2.15    Speed  416
Entry  10    Peck mm  1.93    Speed  395
Entry  11    Peck mm  1.74    Speed  375
Entry  12    Peck mm  1.56    Speed  356
Entry  13    Peck mm  1.5    Speed  356
Entry  14    Peck mm  1.5    Speed  356
Entry  15    Peck mm  1.5    Speed  356
Entry  16    Peck mm  1.5    Speed  356
Entry  17    Peck mm  1.5    Speed  356
Entry  18    Peck mm  1.5    Speed  356
Entry  19    Peck mm  1.5    Speed  356
Entry  20    Peck mm  1.5    Speed  356


Do you have any info re progressive reduction of feed rate?

It would seem sensible to reduce it in line with RPM or you are actually asking the drill to do more work per rev than previously.

What do you think?

regards

Melee


As I said, I reduce feedrate by 10% for each drill diameter in depth beyond 3, just as I do for peck depth.  So, chipload actually decreases as you go deeper, since RPM is only decreasing at 5% per diameter.  If you come up with any refinements on this, I'd love to hear about it.  I've been unable to do much testing, due to electronic problems with my machine, awaiting some parts....

Regards,
Ray L.
Regards,
Ray L.