peck drill cycle-retract

[jferguson4]

I cannot see how to limit the height of the retract in a peck cycle so that once the drill has reached depth of say two diameters, it does not retract higher than the top of the work-piece - idea is to prevent coolant from washing chips into the hole.

If you think this idea is crazy, it won't hurt my feeling if you write it.

[BenLoosli · Accepted solution]

A lot depends on the machine controller rather than the PTC cycle.

Typically, you tell Creo to insert a drill cycle with the peak option and then some parameters like depth, clearance place, feed, etc. The post-processor will generate a G84 cycle command for the machine controller to interpret based on the parameters of the G84 command.

The only way to get what you want is to write a custom peak drill cycle in the post-processor that does not use the G84 command but a series of G80 commands to simulate a G84 with your limited retract plane.

[KenFarley]

In addition to what Ben says, aren't you worried about the possibility that the chips won't be properly evacuated from the hole you are drilling? I've found that the real danger with coolant and chips is when I have a follow-on operation (like reaming) that revisits a drilled hole. Coolant spray from other holes very often shoots the chips everywhere, including the finished holes.

If I have the coolant aimed pretty well I can keep the hole that's currently being worked on pretty well flushed.

[jferguson4]

My thought was to bring the drill-tip up just below the surface and let it spin for a second or two and then back into the hole for the next peck.  I'd assumed it would bring the chips up with it. These are .120 holes .125 deep in 6061-T6.  Machine is a Sherline 2000 (cute little mill) Control is via LinuxCNC so in addition to whatever I can do with G-post, I can also fix up what LinuxCNC does.  

[BenLoosli]

With that shallow (.125) of a depth, I would just plunge the drill with a G80 code. A G84 peak drill cycle will not do much to break the little chip.

We did a drilling operation in mild steel of almost 20 times drill diameter depth (.059 drill, 1.12 deep) in a single plunge. We did a centerdrill operation first on the entire plate (600+ holes) then did the drilling with a tool change every 100 holes. Reloaded the tools when we changed the drilled pieces.