I'm wondering if there's a way to control the height at which the z transitions from rapid plunge to feed when using G83. It appears to be set at .010" now, but my machine's deceleration from rapid on the z takes more than .010", causing the quill to 'bounce' the bit into the part hard before it starts feeding (chipped a couple of bits trying to figure out what was going on). Thanks, Alex. 

If you go into config ports and pins and them choose the mill options tab there is an option to change the G73/G83 peck distance.

Thanks Graham,
That's one of those settings that was  buried away in Mach. Now I remember Brian commenting on it at the Cabin Fever Show when someone asked a similar question about peck drilling.
Not sure you will even find it in the manuals.
RICH

Thanks for the reply Graham, but I think that's the wrong variable for what I want. The problem I have is that the quill rapids back down to .010 above the last height it drilled to, and my machine rapids too fast to slow down to the feed speed in .010", resulting in the bit slamming down into the work at every peck. I think the variable under "ports and pins" controls the height that the bit retracts up to before rapiding down again. I've got Mach 3 , Ver. R3.042.029, which I think is current ( just making sure my " ports and pins" has the same options as yours). Thanks again, Alex

Hi Alex,
  I suspected changing the value circled in the macro would adjust the clearance. I tried several times with different values and still it stays at .01 when running a file.
I may be barking up the wrong tree though.
Just thought I'd give it a shot.
Anxious to see how it's done too.
Russ 

Thanks Russ - I tried that too, with some trepidation ( I know almost nothing about programming ), and I also saw no change. I wondered if there was another macro I'm not looking at, or ? I spent some time on it, and decided to try and find someone smarter than me to figure it out ( that shouldn't be hard...). Alex

I think you will find that the macro M1083.m1s is for turn only. the mill ones are hard coded into mach from what I remember so your only option is to write your drill cycle as a sub program and call it as you need it.

Graham

The problem I have is that the quill rapids back down to .010 above the last height it drilled to, and my machine rapids too fast to slow down to the feed speed in .010", resulting in the bit slamming down into the work at every peck.

Are you sure it's slamming into the work? Just guessing here, but G83 puts Mach in exact stop mode. Is it possible the jerk from the stop makes it appear that it's hitting the work? Because If it's hitting the work, that would mean it's overtravelling and losing position, since your saying it's going at least .01 below where it's supposed to, right?

Thanks Graham, that's what I suspected but wasn't sure of how to say it.
Changing the macro does work in turn as you say though.

Alex, I'm with Gerry.
And......do you have any backlash in your Z ?
Is it a mill or router ?
Any flexing of the structure ?
Otherwise, how could the tool possibly hit the work ?
Russ

My machine is a Bridgeport cnc, upgraded in '08. It does take some time to decelerate from rapid - usually not an issue when I program with Mastercam, because by default it sets the feed plane to start .050 above the surface ( doesn't for G83, because it's a canned cycle control ed by Mach 3). The mill doesn't lose position on any axis, and the rapid takes more than .010" to decelerate in any plane. The quill will 'bounce' on a stop, and be at the correct height to start feeding at the end of the 'bounce', but unfortunately that 'bounce' brings the bit into contact with the work on a G83 ( yes I'm sure - chipped 2 bits on some 304 SS, the second because I thought it was an incorrectly set tool offset that chipped the first. Watched closely the second go round, and the bit bottomed on ever peck). I could slow down the rapid to below it's max, but that seems a waste for every other cycle. I know that many other machines, if not all, need some room for deceleration (not sure how you could go from rapid to zero without some 'bounce' - isn't that the reason for a slow zone with the soft limits, and not setting the feed plane to the exact height of the work surface?). I haven't checked carefully for backlash on the Z - my parts have been dimensionally correct, but since the Z really only cuts on one side of the work, this could still be accomplished with some backlash ( unlike X and Y, which cut with the ball screws loaded both ways). The frame is a dedicated cnc frame ( dovetailed  J head, not fixed ) so it should be stiff enough.

 It sounds like I'll have to learn to use a subprogram - if anyone can point me in the direction of good info on subprograms, I'd appreciate it ( new to me - until recently I had done all my programming line by line.... My first machine was originally run off punch tape).    Thanks for all the input, Alex.