Tap head, post modification help

[Carbonwerkes]

Hi

 

Im running X2 with the MPMaster post, and am looking to run a Tapmatic tap head (auto reversing) on an older mill. Problem is, some Tapmatic types have a modified gear ratio on retract to allow for a faster cycle time. Typically, that is 1.75x the cutting feedrate.

 

The suggested feed on the head is: (1) tap at whatever speed is appropriate for defined RPM/pitch, (2) do a rapid retract of approx 5mm to engage the reverse gearing, and (3) retract at 1.75x the feedrate in #1.

 

I imagine that I can use a feed override for retract (not sure of the control supports that), but rapid retract phase in (2) is not something I know how to implement.

 

Im hoping someone has a post mod for this already that I can incorporate, or use as a guide, as my post coding skills have been limited to much more simple tweaks.

 

Best, and happy holidays-

Roland

[Guest]

Do you have a sample of code? How it is supposed to look?

 

I am thinking a custom drill cycle but what you need for code is the issue at the moment

[gcode]

The simplest way to do this is a tapping subroutine.

Output the holes with a subcall.

If you hardcode all the tapping motion, you will have to edit every hole if you need to change

something.. With a sub routine, one edit will

change all the holes.

If your machine is macro enabled, its even easier

Output a GOTO1000 after ever hole posItion.

then at the end of the program

N1000

G1 (hole depth) F

G0 Z+5mm

G01 Z FEED TO R PLANE

M99

M30

[?Mark]

quote:

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The suggested feed

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I'd not worry about that. Simple feed in - feed out drill cycle will work excellent.

 

quote:

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some Tapmatic types have a modified gear ratio on retract to allow for a faster cycle time. Typically, that is 1.75x the cutting feedrate.

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Are you sure? I've never seen it before. Cycle saving time will be minimal and you can retract faster with any tapmatic head due to a spring mechanism that is build in but modified gear ratio , it's not like I haven't been wring before though

 

If you really want to retract faster then use this long hand method suggested by tapmatic here.

[Carbonwerkes]

Hi John

Presumably, the code for a single hole (X/Y positioning omitted) would be something like:

G90

G00 Z.04

G01 Z-.30 F12.5

G01 Z-.05 F75

G01 Z.250 F21.8

 

So for a 4-40 tap at 500rpm, you feed at 12.5, then at bottom you do a rapid retract of .25" to engage the reverse gearing, and then retract at 1.75*(initial feedrate)- so that at 500rpm spindle speed, and 875rpm tap speed, you are retracting at the appropriate rate (21.8 in this example).

 

So ideally there would just be additional fields to define the reversal retract distance (i.e. .25"), and also the gear ratio for reversal (some are 1:1, others are 1:1.75) for the basic tap operation.

 

Mark- yea, Im 100% sure. If I use a simple bore cycle with feed rate for retract, the head will retract faster than the spindle, and disengage the gearing. The tap motion stops until the spindle retracts another .25" at which point the gear engages, etc. This is not good for the head's internals, and it makes for an ugly thread. There are several models that have this 'feature.' In concept, it is very helpful for machines that do not have tight speed control on the spindle, as long as the code leverages it correctly.

 

Best,

Roland