Searching \ for '[TECH] Confused about taps and dies' in subject line. ()
Make payments with PayPal - it's fast, free and secure! Help us get a faster server
FAQ page: massmind.org/techref/index.htm?key=confused+about+taps
Search entire site for: 'Confused about taps and dies'.

Exact match. Not showing close matches.
PICList Thread
'[TECH] Confused about taps and dies'
2009\06\15@110056 by AGSCalabrese

picon face

I was trying determine the correct die to thread an item ( a PIC of  
course ) and I was surprised to discover the following.
#1   A 3/8 inch die would not start threading a 3/8 inch rod.  I  
understood that the 3/8 indicated the OD of the thread.  The Rod was  
too large.  My calipers say the rod is 3/8 inch OD.
#2   A 3/8 inch die will not screw onto a 3/8 inch bolt of the same  
thread spacing.  Bolt is too large.
#3   A 3/8 inch tap will not screw into a 3/8 inch nut of the same  
thread spacing.
I resolved the issue by remembering that I had seen "adjustable"  
dies.   I cut a slot in my die so it could expand it's diameter.  Then  
it threaded a 3/8 inch rod and the nut screwed on very nicely.  I have  
photos.

Gus


2009\06\15@111230 by Mike Hord

picon face
Was this a 3/8 or 3/8 NPT tap/die pair?

Mike H.

On Mon, Jun 15, 2009 at 10:00 AM, AGSCalabrese<spam_OUTagscalTakeThisOuTspamgmail.com> wrote:
{Quote hidden}

>

2009\06\15@122017 by Carl Denk

flavicon
face


Mike Hord wrote:
> Was this a 3/8 or 3/8 NPT tap/die pair?
>
> Mike H.
>
> On Mon, Jun 15, 2009 at 10:00 AM, AGSCalabrese<.....agscalKILLspamspam@spam@gmail.com> wrote:
>  
>> I was trying determine the correct die to thread an item ( a PIC of
>> course ) and I was surprised to discover the following.
>> #1   A 3/8 inch die would not start threading a 3/8 inch rod.
Chamfer the end of the rod, say 1/8" @45 degrees, nothing fancy, easiest
is with a bench grinder, but file, a little slower will also do the job.
The die should say "start from this side, and that side should be
nearest the rod. What are you holding the die with? A die handle, with
moderate pressure, and being very careful to keep the face of the die
perpendicular to the rod. Many die handles have an adjustable guide on
the side away from "start...", after the rod protrudes beyond the guide,
adjust the guide to be snug. This will help keep the die perpendicular
on longer thread.

>>  I
>> understood that the 3/8 indicated the OD of the thread.  The Rod was
>> too large.  My calipers say the rod is 3/8 inch OD.
>> #2   A 3/8 inch die will not screw onto a 3/8 inch bolt of the same
>> thread spacing.  Bolt is too large.
>>    
The die size should be marked plainly on the die. Are you sure you have
an American and not metric nut and bolt? There are numerous sizes that
are close to the other family, more so in the smaller sizes. Some of
them will start and go about one revolution before binding. One needs to
thread a full nut to ensure. Some nuts and bolt thread are tight to the
tolerance and may not thread on others. The AN spec. used in aircraft
can be this way. And of course, are the bolts, nuts, and die all in
tolerance and not damaged. Running a die on one of these special bolts
may remove a minimum amount of material.

Threads come both with a sharp "V" bottom and top, or radiused edges. A
sharp edge bolt and radiused nut will be an interference fit. The
radiused include the AN series. The radius reduces the stress riser at
sharp corners which is a fatigue issue.
>> #3   A 3/8 inch tap will not screw into a 3/8 inch nut of the same
>> thread spacing.
>> I resolved the issue by remembering that I had seen "adjustable"
>> dies.   I cut a slot in my die so it could expand it's diameter.  Then
>> it threaded a 3/8 inch rod and the nut screwed on very nicely.  I have
>> photos.
>>    
If the die was good condition, should not be necessary. Actually the
adjustable dies are almost rare, and mainly used to make threads that
are at the edge of normal tolerances, usually to match some thread that
is out of tolerance to begin with.

And was mentioned in another message,  besides fine and course threads,
there is tapered pipe threads, which is a much different size (more like
1/2" O.D. since pipe is measured at the I.D.
>> Gus
>>
>>
>> --

2009\06\15@141433 by Herbert Graf

picon face
On Mon, 2009-06-15 at 09:00 -0600, AGSCalabrese wrote:
> I was trying determine the correct die to thread an item ( a PIC of  
> course ) and I was surprised to discover the following.
> #1   A 3/8 inch die would not start threading a 3/8 inch rod.  I  
> understood that the 3/8 indicated the OD of the thread.  The Rod was  
> too large.  My calipers say the rod is 3/8 inch OD.
> #2   A 3/8 inch die will not screw onto a 3/8 inch bolt of the same  
> thread spacing.  Bolt is too large.
> #3   A 3/8 inch tap will not screw into a 3/8 inch nut of the same  
> thread spacing.
> I resolved the issue by remembering that I had seen "adjustable"  
> dies.   I cut a slot in my die so it could expand it's diameter.  Then  
> it threaded a 3/8 inch rod and the nut screwed on very nicely.  I have  
> photos.

That doesn't make sense, are you sure you weren't using perhaps the NPT
tap/dies, they are a different size then the "normal" 3/8" (plus pipe
fittings are very slightly conical in shape).

I haven't used my tap/die set for a while, but size wise everything
seemed correct. A 3/8" die would certainly fit (tightly perhaps) a 3/8"
bolt.

TTYL

2009\06\15@142706 by Michael Rigby-Jones

flavicon
face


{Quote hidden}

I'm wondering if you have confused BSW/BSF and UNC/UNF threads?

Regards

Mike

=======================================================================
This e-mail is intended for the person it is addressed to only. The
information contained in it may be confidential and/or protected by
law. If you are not the intended recipient of this message, you must
not make any use of this information, or copy or show it to any
person. Please contact us immediately to tell us that you have
received this e-mail, and return the original to us. Any use,
forwarding, printing or copying of this message is strictly prohibited.
No part of this message can be considered a request for goods or
services.
=======================================================================

2009\06\15@142940 by Kevin Jones

flavicon
face

The "hole" through the die should be conical. Its larger on one side
than the other. You start the thread with the larger side first. If
you are threading to a shoulder, the you go as far as you can with
the large side leading, back the die completely off, flip it over and
cut up to the shoulder with the small side.

Regards,
Kevin Jones

{Quote hidden}

>

2009\06\15@172753 by Vitaliy

flavicon
face
AGSCalabrese wrote:
> I was trying determine the correct die to thread an item ( a PIC of
> course )

Thread a PIC? I'm trying to imagine what that would look like, or why you
would want to do it. :)

Vitaliy

2009\06\15@174708 by John Gardner

picon face
If you look around, you can sometimes find an old "Machinery's Handbook"
for cheap. Comprehensive info on threads & threading - Such things change
slowly. Lots of info online too - The Engineers Toolbox comes to mind.

Jack

More... (looser matching)
- Last day of these posts
- In 2009 , 2010 only
- Today
- New search...