Helical coil Thread callouts on a drawing 1

[BEAEROHEAD]

In NX 7.5 I am trying to dimension a Helical coil thread. I get #10-32. I am told ASME standard says it should be .190-32, but I can't get that to happen Can anyone tell me if ASME does recommends not to use #10-32 thd and what standard that might be? Thanks in advance

 

[ctopher]

Curious why you would dimension a Helical thread. You could call out the hole to be tapped per Helicoil size.
Helicoil

Look here for thread sizes.
Link

Chris, CSWA
SolidWorks 14
ctopher's home
SolidWorks Legion

 

[ewh]

ASME Y14.6-2001 ¶3.2.1.3 "...Numbered sizes may be shown because of established practices. The decimal equivalent, to three decimal places, should be shown in parentheses. Examples are as follows:
No. 10 (.190)-32 UNF-2A
or
10 (.190)-32 UNF-2A
or
.190-32 UNF-2A"

“Know the rules well, so you can break them effectively.”
-Dalai Lama XIV

 

[KENAT]

So your question is really about thread call outs and possibly how to tweak your installation of NX?

You want to look at ASME B1.1 section 6 & ASME Y14.6 section 3.2. I have the 2003 & 2001 editions respectively and they don't quite mesh on the issue of if number designations alone are legitimate.

Numbered sizes may be shown because of established practices. The decimal equivalent, to three decimal places, should be shown in parentheses.

As to tweaking your installation of NX, I don't know. In Solid Edge we had to tweak a 'holes.txt' file which held the information for screw threads etc.

Posting guidelines faq731-376

http://eng-tips.com/market.cfm?

(probably not aimed specifically at you)
What is Engineering anyway: faq1088-1484​

 

[KENAT]

Sorry, meant to say I suggest you ask your NX question in that forum.

Posting guidelines faq731-376

http://eng-tips.com/market.cfm?

(probably not aimed specifically at you)
What is Engineering anyway: faq1088-1484​

 

[KENAT]

Darn it ewh, you posted while I typed.

Posting guidelines faq731-376

http://eng-tips.com/market.cfm?

(probably not aimed specifically at you)
What is Engineering anyway: faq1088-1484​

 

[drawoh]

BEAEROHEAD,

I don't know about the standard. I figure that when I call up a tapped hole, the machinist selects a tap, and the inspector selects a thread gauge. In either case, tools are labelled 10-32UNF. The .190 part, however accurate, is not particularly useful.

On my drawings, I call up the helical insert as a part. I have a note on the drawing telling the fabricator to follow the manufacturer's instructions. I don't care what tap they use.

--
JHG

 

[ctopher]

I do the same as drawoh.

Chris, CSWA
SolidWorks 14
ctopher's home
SolidWorks Legion

 

[BEAEROHEAD]

This might be a 2 forum post, but mostly I wanted to know if there was an ASME standard that says it should be .190-32 vs #10-32. EWU: I like the #10(.190)-32 as it makes it perfectly clear as NX 7.5 dim shows up #10-32. Note on dwg #10(.190-32) HELICAL COIL INSERT THD PER NASM33537 .XX MIN FULL THD DEPTH.

 

[KENAT]

So drawoh, you're condoning ignoring the standard?;-)

BEAEROHEAD - we use a form like <#10 (.190)-32 UNF-2B> on our drawings. We could never convince ourselves the "#" is actually an approved drawing symbol but went with it anyway.

Posting guidelines faq731-376

http://eng-tips.com/market.cfm?

(probably not aimed specifically at you)
What is Engineering anyway: faq1088-1484​

 

[ctopher]

IMO, the lesser the more clear.
I prefer 10-32. Adding # or .190 is more info than needed.
A machinist knows a 10-32 is .190-32. I have had machinists come back to me trying to meet a 3 place tolerance on .190-32 (not my dwg).

Chris, CSWA
SolidWorks 14
ctopher's home
SolidWorks Legion

 

[drawoh]

Handy, dandy CAD tip...

English numbered screws are based on the formula...

DIA = 0.060 + 0.013[&times;]N...

...where N is the screw number. This makes it easy to model numbered screws in SolidWorks or whatever your favourite CAD package is, complete with correct BOM[&nbsp;]entries.

--
JHG

 

[racookpe1978]

You are forgetting that the Heli-coil is a unique "part" installed INTO a drilled hole MUCH LARGER than the nominal 10-32 "thread size" of the interior threads of the Heli-coil.
Second, you are trying to "dimension" the interior already-threaded !!! hole of the Heli-coil, NOT the actual drilled hole you need to TAP CORRECTLY for the actual OD of the Heli-Coil to get threaded into.
Third, you are confusing a mere 0.002 difference (0.190 nominal) for threaded hole with the "normal" 3/16 (0.1875) drilled hole for a "standard" nbr 10 -32 tapped hole. (Do you seriously think a 0.002 inch difference on diameters from 0.188 to 0.190 will make a difference inside a tapped hole?)

Most often, heli-coils are used two ways: The first is to provide a specific final thread size for future screws to be threaded into in a thin sheetmetal part that is itself too thin to provide a good working anchor.

The second use is the replace an original threaded hole (10-32 in your case) that has been damaged, rounded out, pulled out, or destroyed during operation and use with a repaired threaded hole that can be used again. In both cases, you drill a LARGER hole per the heli-coil spec's for each size, install the heli-coil into that larger hole with the adapter wrench, then install the 10-32 "named" screw into the interior threaded hole of the heli-coil.

from this pdf file from HeliCoil, read the following about hole sizes, and over-large drilled hole sizes, for Helicoils. Then use ONLY the required drill and tap FROM THE HELI-COIL PART LIST.

http://www.stanleyengineeredfastening.com/sites/

http://www.emhartamericas.com/files/downloads/Oversize Twinsert HC943 rev.4.pdf

OVERSIZE TAPPING
Heli-Coil STI tapped holes may become oversize for any one, or combination of the same factors that cause standard tapped holes to be oversize. Heli-Coil provides two insert systems to correct oversize STI tapped holes.
(The Heli-Coil Insert, itself, is the first choice method of correcting standard holes that are oversize.)
OVERSIZE INSERTS
A tapped hole is considered oversize if the Hl (No Go) gage enters more than 3 turns (2 turns for Metric
threads). If this Hl gage enters more than 3 turns, the amount of oversize is not known except by an educated guess based on the degree of wobble of the gage.
This oversize condition of an STI tapped hole can be corrected by an Oversize Insert if the actual pitch diameter of the hole is within Heli-Coil oversize limits, or if it can be retapped with an Oversize STI Tap to within Heli-Coil oversize limits.
For critical applications, Class 2B or 3B Oversize Gages can be ordered for gaging the oversize tapped hole.
This enables determination of the actual class of fit. These are listed in Table 7.
When it has been determined that a tapped hole is oversize, it must next be determined if retapping with the Oversize Tap is necessary. If the Oversize GO Gage will pass through the full length of the hole, it is already large enough to accommodate the oversize insert. The Hl gage can be used to determine if it is a Class 3B or a Class 2B hole.
If the Oversize GO Gage does not enter, it is necessary to retap with the Oversize STI Tap. All proper tapping procedures should be followed to minimize the possibility of the Oversize Tap itself cutting oversize.
The Oversize Tap may remove, approximately, from one ten thousandth of material up to several thousandths.
In removing very small amounts of material, a tap may simply burnish and not cut. In order to minimize this
problem, Heli-Coil Oversize Taps have been made to a slightly larger pitch diameter than if they were cutting an untapped hole. As a result, a Class 3B hole may not be attainable. Also, a Class 2B hole is not always
absolutely assured, depending on the condition of the original oversize hole.
If it is determined that the oversize tapped hole is so large that it is beyond the correction range of Oversize Inserts, a Twinsert assembly can be used

 

[KENAT]

racookpe1978 - what?

You are forgetting that the Heli-coil is a unique "part" installed INTO a drilled hole MUCH LARGER than the nominal 10-32 "thread size" of the interior threads of the Heli-coil.

No, if you see BEAEROHEAD 29 Jul 14 12:39 post it's clear he's calling it up as a separate part. While I'd tend toward doing an assy or similar with parts list... what the OP is doing isn't necessarily wrong given this ends up as an inseparable assembly.

Second, you are trying to "dimension" the interior already-threaded !!! hole of the Heli-coil, NOT the actual drilled hole you need to TAP CORRECTLY for the actual OD of the Heli-Coil to get threaded into.

Not really, OP is just trying to make sure the helical thread size is called out correctly per relevant drawing standard.

Third, you are confusing a mere 0.002 difference (0.190 nominal) for threaded hole with the "normal" 3/16 (0.1875) drilled hole for a "standard" nbr 10 -32 tapped hole. (Do you seriously think a 0.002 inch difference on diameters from 0.188 to 0.190 will make a difference inside a tapped hole?)

Really not sure where you're going here. The mention of .190 is related to the relevant drawing standard saying to use decimal equivalents on thread call outs. Nothing to do with tap drill dia (which doesn't belong on engineering drawing per ASME Y14.5). I'm also confused what a .188 hole would have to do with tapping for a 10-32 thread, seems a little big to me.

Posting guidelines faq731-376

http://eng-tips.com/market.cfm?

(probably not aimed specifically at you)
What is Engineering anyway: faq1088-1484​

 

[drawoh]

...

Most often, heli-coils are used two ways: The first is to provide a specific final thread size for future screws to be threaded into in a thin sheetmetal part that is itself too thin to provide a good working anchor.

Are you sure you are discussing helicoils? For thin sheet metal parts, I use PEM nuts. Helical thread inserts are for thread repairs, and for holes in soft metal.

--
JHG

 

[ctopher]

Helicoils on sheetmetal? I agree with drawoh (and KENAT).

Chris, CSWA
SolidWorks 14
ctopher's home
SolidWorks Legion

 

[MadMango]

We use a leader, TAPPED HOLE FOR 10-32 HELICOIL INSERT, SEE NOTE X. Note X in the General Notes states, FOR ALL TAPPED HOLES FOR HELICOIL INSERTS, FOLLOW RECOMMENDED MANUFACTURER'S INSTALLATION INSTRUCTIONS.

"Art without engineering is dreaming; Engineering without art is calculating."

Have you read faq731-376 to make the best use of these Forums?

 

[ewh]

I've used item number ballons to designate helical coils along with a flag note which directs installation per manufacturers instructions.

I agree that a PEM nut is a better choice for sheet metal than a Helicoil. ;-)

“Know the rules well, so you can break them effectively.”
-Dalai Lama XIV

 

[BEAEROHEAD]

Initial post: Is there an ASME standard which says to use a dim of .190-32 in lieu of #10-32 for a helical insert. I think it got a little confusing. (The 10-32 helical insert is in an aluminum block). Dim on dwg .190-32 HELICAL COIL INSERT THD PER NASM33537 or #10-32 HELICAL COIL INSERT THD PER NASM33537.

 

[ctopher]

In BOM: NASM33537, QTY X
Hole callout: TAPPED HOLE FOR 10-32 HELICOIL INSERT, SEE NOTE X. (with BOM balloon)
Note X in the General Notes states, FOR ALL TAPPED HOLES FOR HELICOIL INSERTS, FOLLOW RECOMMENDED MANUFACTURER'S INSTALLATION INSTRUCTIONS

This will cover you.

Chris, CSWA
SolidWorks 14
ctopher's home
SolidWorks Legion