Tapped Hole Drill Depth

[qnen]

Hopefully a real easy question,  how does Creo4 determine the default drill depth for a tapped hole.   I know the .hol tables have the diameters and ratio of threaded depth vs hole depth, but I can not find where the default drill depth for a 1/4-20 blind hole is set.

Thanks

[TomD.inPDX]

Probably the percent thread callout in the *.hol tables.

When you create a hole from the tables, the system takes the below hole data and converts it yet again for formatting the hole note.

TABLE_DATA
PRO_VERSION    24
THREAD_SERIES  UNC
CLASS          2B
TABLE_UNITS    inch
DEPTH_RATIO    1.25
CALLOUT_FORMAT

THREAD_DATA
FASTENER_ID  BASIC_DIAM  THREAD  TAP_DR  TAP_DEC  PERCENT_THREAD  CLEAR_DR_CLOSE  CLOSE_DEC  CLEAR_DR_FREE  FREE_DEC  CLEAR_DR_MED  MED_DEC  CBOREDIAM   CBOREDEPTH   CSINKDIAM   CSINKANGLE   BOTCSINKDIAM   BOTCSINKANGLE

[dschenken]

THREAD_LENGTH governs the tapped portion.

DRILL_DEPTH governs the drilled portion.

DEPTH_RATIO

The relationship between the thread depth and the drill depth (for example, 1.25). When you enter either the thread depth or the drill depth on the Hole tab, the other value is calculated automatically using this ratio. Drill Depth is Thread Depth multiplied by Depth Ratio.

You can override the default relationship of the depth ratio by entering both the Drill Depth and the Thread Depth values on the Hole tab, under the condition that the drill depth value is greater than or equal to the thread depth.

Ref http://support.ptc.com/help/creo/creo_pma/usascii/#page/part_modeling%2Fpart_modeling%2Fpart_nine_sub%2FUsing_Hole_Charts.html%23

[gpeetersem]

Hi dschenken,

I'm trying to integrate the parameters THREAD_LENGTH and DRILL_DEPTH in my hole-table, but this doesn't seem to work. (see attached hole-table; I've put ".txt" in the name, because otherwise I wasn't able to upload the file).

What I want to have, is per hole-diameter a pre-defined drill-depth and thread-length (to test, in my table this is for each diameter 10mm and 8mm):

In my hole table I still have the DEPTH_RATIO on top, but when I will remove this, my table doesn't work:

For the rest I don't really know what the parameter "percent_thread" does mean...

I've allready checked the link below, but this doesn't help me a lot: http://support.ptc.com/help/creo/creo_pma/usascii/#page/part_modeling%2Fpart_modeling%2Fpart_nine_sub%2FUsing_Hole_Charts.html%23

[TomU]

I think you are misreading the statement from the help page.  It's not saying you can override these values in the .hol file (by adding extra columns), it's saying you can override them (one at a time) in the user interface (hole "tab") when creating the hole.  To the best of my knowledge it's still not possible to control hole depth AND thread depth in the .hol files.  See CS99906.

[gpeetersem]

Hi TomU,

thanks for your answer. So now I know that I don't have to search for a solution...

[BenLoosli]

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@gpeetersem wrote:

For the rest I don't really know what the parameter "percent_thread" does mean...

I've allready checked the link below, but this doesn't help me a lot: http://support.ptc.com/help/creo/creo_pma/usascii/#page/part_modeling%2Fpart_modeling%2Fpart_nine_sub%2FUsing_Hole_Charts.html%23

---

In that link it explains that percent_thread is the ratio of thread to major diameter. In other words, the major diameter minus the tap drill diameter divided by a constant times the threads/inch.

See this link to explain it better: http://www.balax.com/catalog/technical-information/thread-percentage-calculation