[Healeys] Taps and Dies

[Perry]

Dies are intended to cut new male threads on a pipe or rod. That operation is called threading. A tap is intended to cut female threads in a hole, thus called tapping.  Both taps and dies can be used to chase an existing thread, process is chasing. Trick to getting clean, straight threads with a die is to make a chamfer on the end of the pipe or rod, about 30 degrees works well.

To Tom’s original question it would seem it would take a smaller diameter thread size than a ½ inch die to form a usable thread on a ½ inch outer diameter pipe. The root or minor diameter of the ½ inch thread is just slightly less than the pipe. 

However at this point I’m all tapped out……
Perry 

Sent from Mail for Windows 10

From: John Spaur
Sent: Wednesday, May 13, 2020 1:39 PM
To: 'Bob Spidell'; healeys at autox.team.net
Subject: Re: [Healeys] BSF Taps and Dies

With the correctly sized die for the pipe or rod, threads can be cut.
John

-----Original Message-----
From: Healeys [mailto:healeys-bounces at autox.team.net] On Behalf Of Bob Spidell
Sent: Wednesday, May 13, 2020 8:18 AM
To: healeys at autox.team.net
Subject: Re: [Healeys] BSF Taps and Dies

My (somewhat limited) experience is that the so-called 'dies' are really only thread chasers. If you try to use them to actually thread, say, a pipe or rod the die will wander laterally and you won't get a straight thread. I don't know if actual 'dies' are available outside a machine shop but, probably the only way to get a straight thread is with a lathe.

On 5/13/2020 6:49 AM, Bob Haskell wrote:
> Tom,
>
> If the pipe is 1/2" outside diameter, then a 1/2"-13 UNC or 20 UNF die 
> would be used.  Pipe is usually given by the inside diameter and 
> normally has tapered threads (NPT), in the US.  A 1/2" pipe would use 
> a 1/2" NPT die which is much larger than the 1/2"-13 or 20 dies.
>
> Cheers,
>
> Bob Haskell
> Austin Healey 3000 BN7/BT7 registrar
>
> On 5/13/20 7:12 AM, Tom Felts wrote:
>> Totally off Healey content, but here is a stupid question Re. dies. I 
>> have a piece of 1/2" OD steel pipe I want to thread (the outside).
>> I don't know the die size to use.  A 1/2" die seems way too small. 
>> Anyone know what size die to use?  the number of threads doesn't 
>> matter---just the size of the die.
>> Thanks
>> Tom
>>
>> ----- Original Message -----
>> From: Michael MacLean <rrengineer.mike at att.net>
>> To: 'Healeys' <healeys at autox.team.net>, simon lachlan 
>> <simon.lachlan at alexarevel.plus.com>
>> Sent: Wed, 13 May 2020 02:51:28 -0400 (EDT)
>> Subject: Re: [Healeys] BSF Taps and Dies
>>
>>
>> I just want them to clean up threads.  Should be adequate for that..
>> Mike M
>>
>

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