Date   

Re: UNC Taps

EricJ
 

I think this one is not O.T. personally. If it helps some fellow Tekkies to not destroy their tools or scopes, that seems pretty on-topic to me. It also seems that there is a good sized group of fellows here that appreciated that information and will hopefully make good use of it.
--Eric
Sent from my Samsung Galaxy smartphone.

-------- Original message --------From: Dennis Tillman W7PF <dennis@ridesoft.com> Date: 1/19/19 5:22 PM (GMT-06:00) To: TekScopes@groups.io Subject: Re: [TekScopes] UNC Taps
Since you ask:
It is important that the group develop its own guidelines about what is or is not appropriate content.

Dennis Tillman W7PF

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Jim
Ford
Sent: Saturday, January 19, 2019 1:59 PM
Subject: Re: [TekScopes] UNC Taps

Like I said, Chuck, great information, but time to get off the tapping
bandwagon and get back to Tek Scopes.
Dennis, what say you?
Jim F


Sent from my Verizon, Samsung Galaxy smartphone
-------- Original message --------From: Chuck Harris <cfharris@erols.com>
Date: 1/19/19  5:46 AM  (GMT-08:00) To: TekScopes@groups.io Subject: Re:
[TekScopes] UNC Taps How can a polite discussion of how to find, and how to
safely use, the tools we need to restore our scopes be off topic?

If you don't like a topic, or find the subject of a thread uninteresting,
exercise your personal prerogative, and don't read it.

You needn't inform the group, nor ask its permission.

-Chuck Harris

Jim Ford wrote:
OK, everybody, while I've gotten a hell of an education, it's time to put
this OT thread to bed.
Thanks.
Jim F

Sent from my Verizon, Samsung Galaxy smartphone
-------- Original message --------From: Chuck Harris
<cfharris@erols.com> Date: 1/18/19  9:33 PM  (GMT-08:00) To:
TekScopes@groups.io Subject: Re: [TekScopes] UNC Taps It's probably
also worth mentioning that there are taps for hand tapping, and taps
for machine tapping...  The taps you get in the typical kit are for
hand tapping only, and that means finger power, not with a drill press
and a tap-matic head.



--
Dennis Tillman W7PF
TekScopes Moderator


Re: UNC Taps

Dan Cordova <danny_cordov@...>
 

I'm a retired machinist and have learned from this post.
Anyone can delete the email or hit the mute...

From: Richard Solomon <dickw1ksz@gmail.com>
To: TekScopes <TekScopes@groups.io>
Sent: Saturday, January 19, 2019 3:27 PM
Subject: Re: [TekScopes] UNC Taps

Speaking as a real hack with
mechanical things, I have
learned a lot from this thread.

Not all of us are died in the
wool tool and die makers.

Thanks for the info,

73, Dick, W1KSZ

On Sat, Jan 19, 2019 at 4:22 PM Dennis Tillman W7PF <dennis@ridesoft.com>
wrote:

Since you ask:
It is important that the group develop its own guidelines about what is or
is not appropriate content.

Dennis Tillman W7PF

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Jim
Ford
Sent: Saturday, January 19, 2019 1:59 PM
Subject: Re: [TekScopes] UNC Taps

Like I said, Chuck, great information, but time to get off the tapping
bandwagon and get back to Tek Scopes.
Dennis, what say you?
Jim F


Sent from my Verizon, Samsung Galaxy smartphone
-------- Original message --------From: Chuck Harris <cfharris@erols.com

Date: 1/19/19  5:46 AM  (GMT-08:00) To: TekScopes@groups.io Subject: Re:
[TekScopes] UNC Taps How can a polite discussion of how to find, and how
to
safely use, the tools we need to restore our scopes be off topic?

If you don't like a topic, or find the subject of a thread uninteresting,
exercise your personal prerogative, and don't read it.

You needn't inform the group, nor ask its permission.

-Chuck Harris

Jim Ford wrote:
OK, everybody, while I've gotten a hell of an education, it's time to
put
this OT thread to bed.
Thanks.
Jim F

Sent from my Verizon, Samsung Galaxy smartphone
-------- Original message --------From: Chuck Harris
<cfharris@erols.com> Date: 1/18/19  9:33 PM  (GMT-08:00) To:
TekScopes@groups.io Subject: Re: [TekScopes] UNC Taps It's probably
also worth mentioning that there are taps for hand tapping, and taps
for machine tapping...  The taps you get in the typical kit are for
hand tapping only, and that means finger power, not with a drill press
and a tap-matic head.



--
Dennis Tillman W7PF
TekScopes Moderator




Re: UNC Taps

Richard Solomon <dickw1ksz@...>
 

Speaking as a real hack with
mechanical things, I have
learned a lot from this thread.

Not all of us are died in the
wool tool and die makers.

Thanks for the info,

73, Dick, W1KSZ

On Sat, Jan 19, 2019 at 4:22 PM Dennis Tillman W7PF <dennis@ridesoft.com>
wrote:

Since you ask:
It is important that the group develop its own guidelines about what is or
is not appropriate content.

Dennis Tillman W7PF

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Jim
Ford
Sent: Saturday, January 19, 2019 1:59 PM
Subject: Re: [TekScopes] UNC Taps

Like I said, Chuck, great information, but time to get off the tapping
bandwagon and get back to Tek Scopes.
Dennis, what say you?
Jim F


Sent from my Verizon, Samsung Galaxy smartphone
-------- Original message --------From: Chuck Harris <cfharris@erols.com

Date: 1/19/19 5:46 AM (GMT-08:00) To: TekScopes@groups.io Subject: Re:
[TekScopes] UNC Taps How can a polite discussion of how to find, and how
to
safely use, the tools we need to restore our scopes be off topic?

If you don't like a topic, or find the subject of a thread uninteresting,
exercise your personal prerogative, and don't read it.

You needn't inform the group, nor ask its permission.

-Chuck Harris

Jim Ford wrote:
OK, everybody, while I've gotten a hell of an education, it's time to
put
this OT thread to bed.
Thanks.
Jim F

Sent from my Verizon, Samsung Galaxy smartphone
-------- Original message --------From: Chuck Harris
<cfharris@erols.com> Date: 1/18/19 9:33 PM (GMT-08:00) To:
TekScopes@groups.io Subject: Re: [TekScopes] UNC Taps It's probably
also worth mentioning that there are taps for hand tapping, and taps
for machine tapping... The taps you get in the typical kit are for
hand tapping only, and that means finger power, not with a drill press
and a tap-matic head.



--
Dennis Tillman W7PF
TekScopes Moderator




Re: Tek Probe Cables free to a good home

Artekmedia <manuals@...>
 

Gotta be in the RPR's somewhere 8^)

On 1/19/2019 5:42 PM, Dennis Tillman W7PF wrote:
I have the following probe cables which I do not need.

If somebody can identify what they are for, or they can use one or more of
them:

PLEASE CONTACT ME OFF LIST AT DENNIS AT RIDESOFT DOT COM


175-8011-00

175-3217-00

175-1205-00

175-0281-00


Dennis Tillman w7pf




--
Dave
Manuals@ArtekManuals.com
www.ArtekManuals.com


Re: UNC Taps

 

Since you ask:
It is important that the group develop its own guidelines about what is or is not appropriate content.

Dennis Tillman W7PF

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Jim
Ford
Sent: Saturday, January 19, 2019 1:59 PM
Subject: Re: [TekScopes] UNC Taps

Like I said, Chuck, great information, but time to get off the tapping
bandwagon and get back to Tek Scopes.
Dennis, what say you?
Jim F


Sent from my Verizon, Samsung Galaxy smartphone
-------- Original message --------From: Chuck Harris <cfharris@erols.com>
Date: 1/19/19 5:46 AM (GMT-08:00) To: TekScopes@groups.io Subject: Re:
[TekScopes] UNC Taps How can a polite discussion of how to find, and how to
safely use, the tools we need to restore our scopes be off topic?

If you don't like a topic, or find the subject of a thread uninteresting,
exercise your personal prerogative, and don't read it.

You needn't inform the group, nor ask its permission.

-Chuck Harris

Jim Ford wrote:
OK, everybody, while I've gotten a hell of an education, it's time to put
this OT thread to bed.
Thanks.
Jim F

Sent from my Verizon, Samsung Galaxy smartphone
-------- Original message --------From: Chuck Harris
<cfharris@erols.com> Date: 1/18/19 9:33 PM (GMT-08:00) To:
TekScopes@groups.io Subject: Re: [TekScopes] UNC Taps It's probably
also worth mentioning that there are taps for hand tapping, and taps
for machine tapping... The taps you get in the typical kit are for
hand tapping only, and that means finger power, not with a drill press
and a tap-matic head.



--
Dennis Tillman W7PF
TekScopes Moderator


Tek Probe Cables free to a good home

 

I have the following probe cables which I do not need.

If somebody can identify what they are for, or they can use one or more of
them:

PLEASE CONTACT ME OFF LIST AT DENNIS AT RIDESOFT DOT COM



175-8011-00

175-3217-00

175-1205-00

175-0281-00



Dennis Tillman w7pf


Re: UNC Taps

Jim Ford
 

Like I said, Chuck, great information, but time to get off the tapping bandwagon and get back to Tek Scopes.
Dennis, what say you?
Jim F


Sent from my Verizon, Samsung Galaxy smartphone

-------- Original message --------From: Chuck Harris <cfharris@erols.com> Date: 1/19/19 5:46 AM (GMT-08:00) To: TekScopes@groups.io Subject: Re: [TekScopes] UNC Taps
How can a polite discussion of how to find, and how
to safely use, the tools we need to restore our scopes
be off topic?

If you don't like a topic, or find the subject of a
thread uninteresting, exercise your personal prerogative,
and don't read it.

You needn't inform the group, nor ask its permission.

-Chuck Harris

Jim Ford wrote:
OK, everybody, while I've gotten a hell of an education, it's time to put this OT thread to bed.
Thanks.
Jim F




Sent from my Verizon, Samsung Galaxy smartphone
-------- Original message --------From: Chuck Harris <cfharris@erols.com> Date: 1/18/19  9:33 PM  (GMT-08:00) To: TekScopes@groups.io Subject: Re: [TekScopes] UNC Taps
It's probably also worth mentioning that there are taps for
hand tapping, and taps for machine tapping...  The taps you
get in the typical kit are for hand tapping only, and that
means finger power, not with a drill press and a tap-matic
head.


Tek's new president tours vintageTEK

 

I thought these two articles would be of interest to the group.



<https://vintagetek.org/tektronix-presidents-tour/>
https://vintagetek.org/tektronix-presidents-tour/


<https://www.oregonlive.com/silicon-forest/2019/01/tektronix-names-new-presi
dent-marc-tremblay.html>
https://www.oregonlive.com/silicon-forest/2019/01/tektronix-names-new-presid
ent-marc-tremblay.html



I found the last paragraph of the 2nd article to be particularly interesting

"Once Oregon's signature tech company, Tektronix is now greatly diminished
but remains among the state's largest technology employers. It employs
hundreds, perhaps more than 1,000 (Fortive won't say how many) at its
250-acre campus near Beaverton."



Dennis Tillman W7PF


Re: TDS-420A power supply repair

Brendan
 

Brian
Jan 18 #153753

I have a bad psu in my TDS-420A , it burned a track on the pcb bur I cannot find the cause , the switching transistor os it seems . I have had it suggested that the hybrid device is probably the fault , does anyone know what the device consists of , or better still does anyone actually have one that they would part with .

Thanks in advance for any help you can give


On Sat, Jan 19, 2019 at 08:22 AM, Bob Koller wrote:


Where is the burn? Can you post a picture?

I just finished two of these PSU's, I think you need to replace ALL of the
small electrolytic caps, don't bother testing, etc, just replace, they are all
past it.
One of the problem areas in this unit is the black potted mains switching
circuit in the primary. It controls the input doubler configuration by
automatically sensing 120 vs 240 mains input. It can be removed and jumped
across.
The other issue is the regulator board mounted vertically near the output
connector. These can get dirty from the fan, causing leakage paths, and
subsequent erroneous shutdown signals.
That is identical to the power supply I just fixed. Every single capacitor on the power supply board was bad. Either in the process of leaking or already leaked out and dried out. After replacing those and the all know SMD caps issue all seems well. You may want to check that the output connector joints are solid as well,just in case.


Re: TDS-420A power supply repair

Bob Koller <testtech@...>
 

Where is the burn? Can you post a picture?

I just finished two of these PSU's, I think you need to replace ALL of the small electrolytic caps, don't bother testing, etc, just replace, they are all past it.
One of the problem areas in this unit is the black potted mains switching circuit in the primary. It controls the input doubler configuration by automatically sensing 120 vs 240 mains input. It can be removed and jumped across.
The other issue is the regulator board mounted vertically near the output connector. These can get dirty from the fan, causing leakage paths, and subsequent erroneous shutdown signals.


Re: vintageTEK museum releases Replaceable Parts Registry (RPR)

victor.silva
 

Very nice information. Is anything like this available for after 1986, say 1986 through 1995? I'm looking for 2465B/67B information.

If only Tek released their source control drawings, wishful thinking.

--Victor


Re: UNC Taps

Chuck Harris <cfharris@...>
 

How can a polite discussion of how to find, and how
to safely use, the tools we need to restore our scopes
be off topic?

If you don't like a topic, or find the subject of a
thread uninteresting, exercise your personal prerogative,
and don't read it.

You needn't inform the group, nor ask its permission.

-Chuck Harris

Jim Ford wrote:

OK, everybody, while I've gotten a hell of an education, it's time to put this OT thread to bed.
Thanks.
Jim F




Sent from my Verizon, Samsung Galaxy smartphone
-------- Original message --------From: Chuck Harris <cfharris@erols.com> Date: 1/18/19 9:33 PM (GMT-08:00) To: TekScopes@groups.io Subject: Re: [TekScopes] UNC Taps
It's probably also worth mentioning that there are taps for
hand tapping, and taps for machine tapping... The taps you
get in the typical kit are for hand tapping only, and that
means finger power, not with a drill press and a tap-matic
head.


Re: 7104 -7854 SMPS Dummy Load Construction Article

tek_547
 

Very usefull, thanx!
René


Re: 7104 -7854 SMPS Dummy Load Construction Article

Glydeck
 

Dennis,

Nicely done! Thanks.

George

On Jan 18, 2019, at 6:38 PM, Dennis Tillman W7PF <dennis@ridesoft.com> wrote:

I uploaded a 2 page article to the Files section of TekScopes on how to
build a dummy load for testing the 7104 and 7854 Switching Mode Power
Supplies. You can find it by going to the files section and searching for
7104.



The full name of the file is: 7104 - 7854 SMPS Dummy Load.docx



The link address is

https://groups.io/g/TekScopes/files/7104%20-%207854%20SMPS%20Dummy%20Load.do
cx



Thanks to those who made suggestions for what load resistors to use.



Dennis Tillman W7PF






Re: UNC Taps

Jim Ford
 

OK, everybody, while I've gotten a hell of an education, it's time to put this OT thread to bed.
Thanks.
Jim F




Sent from my Verizon, Samsung Galaxy smartphone

-------- Original message --------From: Chuck Harris <cfharris@erols.com> Date: 1/18/19 9:33 PM (GMT-08:00) To: TekScopes@groups.io Subject: Re: [TekScopes] UNC Taps
It's probably also worth mentioning that there are taps for
hand tapping, and taps for machine tapping...  The taps you
get in the typical kit are for hand tapping only, and that
means finger power, not with a drill press and a tap-matic
head.

Count the number of flutes, and that is the fraction of a
turn you can go forward before backing up 1/2 turn to break the
chip.  When you get past the heavy cutting, you can turn
more without backing up.

-Chuck Harris

Harvey White wrote:
On Fri, 18 Jan 2019 13:40:08 -0500, you wrote:

Dave (and others):
I'll add one other thing, which may be overlooked.  The tap MUST be
perpendicular to the hole that you're tapping.  If not, then the tap
does not center itself automatically, but could try to tap a slanted
hole.  This causes the tap to try to excavate the wall of the hole on
one side, and barely cut the other.  This can result in the tap
jamming and breaking.

Always use a standard tap (very tapered) for the first hole.  Then use
a less tapered tap for the bottom threads, and if you must have a
thread to the bottom of the hole, use a bottoming (names may vary)
tap.  Do not use the taps in the wrong sequence.

I have a tapping setup which guarantees perpendicular tapping.  I also
(when on a drill press) use a hand tap and a tapping center (it's
spring loaded and presses down on the little hole in the tap handle).
Again, the main point is alignment.

Never try to hold the metal being tapped and the tap itself while
tapping.  (don't ask).

I'd suggest such a thing as tap-free, which comes in standard and then
aluminum versions.

I will back the tap completely out to clear the chips if the tap
starts to feel too resistant to turning.

Harvey

Harvey


Re: UNC Taps

Chuck Harris <cfharris@...>
 

It's probably also worth mentioning that there are taps for
hand tapping, and taps for machine tapping... The taps you
get in the typical kit are for hand tapping only, and that
means finger power, not with a drill press and a tap-matic
head.

Count the number of flutes, and that is the fraction of a
turn you can go forward before backing up 1/2 turn to break the
chip. When you get past the heavy cutting, you can turn
more without backing up.

-Chuck Harris

Harvey White wrote:

On Fri, 18 Jan 2019 13:40:08 -0500, you wrote:

Dave (and others):
I'll add one other thing, which may be overlooked. The tap MUST be
perpendicular to the hole that you're tapping. If not, then the tap
does not center itself automatically, but could try to tap a slanted
hole. This causes the tap to try to excavate the wall of the hole on
one side, and barely cut the other. This can result in the tap
jamming and breaking.

Always use a standard tap (very tapered) for the first hole. Then use
a less tapered tap for the bottom threads, and if you must have a
thread to the bottom of the hole, use a bottoming (names may vary)
tap. Do not use the taps in the wrong sequence.

I have a tapping setup which guarantees perpendicular tapping. I also
(when on a drill press) use a hand tap and a tapping center (it's
spring loaded and presses down on the little hole in the tap handle).
Again, the main point is alignment.

Never try to hold the metal being tapped and the tap itself while
tapping. (don't ask).

I'd suggest such a thing as tap-free, which comes in standard and then
aluminum versions.

I will back the tap completely out to clear the chips if the tap
starts to feel too resistant to turning.

Harvey

Harvey


Re: UNC Taps

Frank DuVal
 

Boelube


Drilling or tapping, Boelube.

Pricey but good.


https://www.boelube.com/


Frank DuVal

On 1/18/2019 7:32 PM, Harvey White wrote:
On Fri, 18 Jan 2019 13:40:08 -0500, you wrote:

Dave (and others):
I'd suggest such a thing as tap-free, which comes in standard and then
aluminum versions.

I will back the tap completely out to clear the chips if the tap
starts to feel too resistant to turning.

Harvey


7104 -7854 SMPS Dummy Load Construction Article

 

I uploaded a 2 page article to the Files section of TekScopes on how to
build a dummy load for testing the 7104 and 7854 Switching Mode Power
Supplies. You can find it by going to the files section and searching for
7104.



The full name of the file is: 7104 - 7854 SMPS Dummy Load.docx



The link address is

https://groups.io/g/TekScopes/files/7104%20-%207854%20SMPS%20Dummy%20Load.do
cx



Thanks to those who made suggestions for what load resistors to use.



Dennis Tillman W7PF


Re: UNC Taps

EricJ
 

He was talking about the entire hole not being perpendicular to the surface. This does occur by design occasionally but it's not very common. The tap absolutely has to be perpendicular to the hole or it will break. And it's not necessary to use a taper tap except in difficult/exotic materials; a plug tap will almost always suffice. Bottoming tap should only be used to finish the last few threads as you noted. It's absolutely a very good idea to use a tapping fluid of some sort - even when just chasing threads - and regarding the chip clogging - I was taught to reverse the tap every rotation or so to break the chips into small pieces. This makes them much less likely to clog the flutes and bind the tap. If you feel the tap getting tight, back it all the way out and blow out the hole. (Cover the hole with a rag first so you don't end up in the E.R. while they dig a sharp chunk of metal out of your eyeball. Taps are also much less likely to clog in a blind hole if there's plenty of hole past where your thread depth stops. In other words, if you can drill through or considerably deeper than the thread depth. A big cause of tap breakage is fellows trying to tap all the way to the bottom of a hole and crashing into the end of the drilled hole with the tap.
--Eric
Sent from my Samsung Galaxy smartphone.

-------- Original message --------From: Harvey White <madyn@dragonworks.info> Date: 1/18/19 6:32 PM (GMT-06:00) To: TekScopes@groups.io Subject: Re: [TekScopes] UNC Taps
On Fri, 18 Jan 2019 13:40:08 -0500, you wrote:

Dave (and others):
I'll add one other thing, which may be overlooked.  The tap MUST be
perpendicular to the hole that you're tapping.  If not, then the tap
does not center itself automatically, but could try to tap a slanted
hole.  This causes the tap to try to excavate the wall of the hole on
one side, and barely cut the other.  This can result in the tap
jamming and breaking.

Always use a standard tap (very tapered) for the first hole.  Then use
a less tapered tap for the bottom threads, and if you must have a
thread to the bottom of the hole, use a bottoming (names may vary)
tap.  Do not use the taps in the wrong sequence.

I have a tapping setup which guarantees perpendicular tapping.  I also
(when on a drill press) use a hand tap and a tapping center (it's
spring loaded and presses down on the little hole in the tap handle).
Again, the main point is alignment.

Never try to hold the metal being tapped and the tap itself while
tapping.  (don't ask).

I'd suggest such a thing as tap-free, which comes in standard and then
aluminum versions.

I will back the tap completely out to clear the chips if the tap
starts to feel too resistant to turning.

Harvey

Harvey



The suggestions for removing broken tap(s) provided by Dave are
excellent- I for one was not aware of these methods.  I might also add a
few suggestions about using a tap when tapping a drilled hole- first, to
avoid overstressing and breaking a tap in the first place, the tap
should be advanced into the material only a small amount- say, about one
or one-and-a-half turns at a time, and then backed out (to remove any
chips).  Then go in a bit past the previous depth, and repeat.  Continue
this repetitive cycle until desired thread depth is achieved.  I suspect
that some users of taps advance the tap all the way to the desired
depth, and then are frustrated when it cannot be backed out (and gets
jammed) due to chip clogging.  And possibly the tap breaks at this point.

Another suggestion is to use some sort of cutting oil when threading the
hole.  Oils specifically identified as cutting oils are ideal, but many
other oils will suffice in a pinch- motor oil, 3-in-1, WD-40, etc.  I
have often taken a bit of oil from a car's engine dipstick- it's dirty
but works.

Finally, when trying to re-thread a previously tapped but somehow
"butchered" threaded hole, it's useful to try to gently advance the tap
into the partially threaded (partially damaged?) hole initially by hand
(without a tap wrench) so that the tap is properly aligned with the
hole's old threads.  Doing this by hand allows for a sense of "feel" to
get the alignment right.

These tips also apply to using dies to re-thread bolts and the like. 
And as others have mentioned, mcmaster.com (in the US) is an ideal
source, in my opinion, for all kinds of taps and other "good stuff".

I'm far from an expert on tapping or machining of metals, but my father
(a tool-and-die maker, and machinist) passed these tips on to me.

Mike Dinolfo N4MWP

On 1/18/19 1:49 PM, Daveolla wrote:
Years ago in the model shop at NCR I became quite the expert at
extracting broken taps, from sliding bits of piano wire down the
flutes and griping them with pliers and unscrewing them, to dripping
oven cleaner into the aluminum to help lossen them up , to using
carbide tipped vibrating engraving tools to  chip away at tap , and so
on and so on. They will come out  just get those creating juices flowing.

There is a big advantage sometimes in using cheap taps in cast,
aluminum or brass especially for newbies that may not now how far they
can torque before a good one breaks. I have some that are so soft that
they will twist instead of breaking and leave you with a spiral fluted
tap. You can then clean up threads later with a good quality sharp tap.

Some of those black finished taps like from Harbour Freight or
Princess Auto or Canadian Tire (in Canada......duh)  are more tolerant
to breaking,  not to the point of twisting into a spiral though. I
suggested those black ones to a nephew that was wanting some for
motorcycle and old auto repair. Figured it might save him the learning
curve of how far he can push his luck  before his is stuck with an
assumed disaster stuck in the hole.

At 11:49 AM 1/17/2019, you wrote:
You don't want to have to extract a broken tap.
Been there - suffered the pain.

Dave










Re: UNC Taps

Harvey White
 

On Fri, 18 Jan 2019 13:40:08 -0500, you wrote:

Dave (and others):
I'll add one other thing, which may be overlooked. The tap MUST be
perpendicular to the hole that you're tapping. If not, then the tap
does not center itself automatically, but could try to tap a slanted
hole. This causes the tap to try to excavate the wall of the hole on
one side, and barely cut the other. This can result in the tap
jamming and breaking.

Always use a standard tap (very tapered) for the first hole. Then use
a less tapered tap for the bottom threads, and if you must have a
thread to the bottom of the hole, use a bottoming (names may vary)
tap. Do not use the taps in the wrong sequence.

I have a tapping setup which guarantees perpendicular tapping. I also
(when on a drill press) use a hand tap and a tapping center (it's
spring loaded and presses down on the little hole in the tap handle).
Again, the main point is alignment.

Never try to hold the metal being tapped and the tap itself while
tapping. (don't ask).

I'd suggest such a thing as tap-free, which comes in standard and then
aluminum versions.

I will back the tap completely out to clear the chips if the tap
starts to feel too resistant to turning.

Harvey

Harvey



The suggestions for removing broken tap(s) provided by Dave are
excellent- I for one was not aware of these methods.  I might also add a
few suggestions about using a tap when tapping a drilled hole- first, to
avoid overstressing and breaking a tap in the first place, the tap
should be advanced into the material only a small amount- say, about one
or one-and-a-half turns at a time, and then backed out (to remove any
chips).  Then go in a bit past the previous depth, and repeat.  Continue
this repetitive cycle until desired thread depth is achieved.  I suspect
that some users of taps advance the tap all the way to the desired
depth, and then are frustrated when it cannot be backed out (and gets
jammed) due to chip clogging.  And possibly the tap breaks at this point.

Another suggestion is to use some sort of cutting oil when threading the
hole.  Oils specifically identified as cutting oils are ideal, but many
other oils will suffice in a pinch- motor oil, 3-in-1, WD-40, etc.  I
have often taken a bit of oil from a car's engine dipstick- it's dirty
but works.

Finally, when trying to re-thread a previously tapped but somehow
"butchered" threaded hole, it's useful to try to gently advance the tap
into the partially threaded (partially damaged?) hole initially by hand
(without a tap wrench) so that the tap is properly aligned with the
hole's old threads.  Doing this by hand allows for a sense of "feel" to
get the alignment right.

These tips also apply to using dies to re-thread bolts and the like. 
And as others have mentioned, mcmaster.com (in the US) is an ideal
source, in my opinion, for all kinds of taps and other "good stuff".

I'm far from an expert on tapping or machining of metals, but my father
(a tool-and-die maker, and machinist) passed these tips on to me.

Mike Dinolfo N4MWP

On 1/18/19 1:49 PM, Daveolla wrote:
Years ago in the model shop at NCR I became quite the expert at
extracting broken taps, from sliding bits of piano wire down the
flutes and griping them with pliers and unscrewing them, to dripping
oven cleaner into the aluminum to help lossen them up , to using
carbide tipped vibrating engraving tools to  chip away at tap , and so
on and so on. They will come out  just get those creating juices flowing.

There is a big advantage sometimes in using cheap taps in cast,
aluminum or brass especially for newbies that may not now how far they
can torque before a good one breaks. I have some that are so soft that
they will twist instead of breaking and leave you with a spiral fluted
tap. You can then clean up threads later with a good quality sharp tap.

Some of those black finished taps like from Harbour Freight or
Princess Auto or Canadian Tire (in Canada......duh)  are more tolerant
to breaking,  not to the point of twisting into a spiral though. I
suggested those black ones to a nephew that was wanting some for
motorcycle and old auto repair. Figured it might save him the learning
curve of how far he can push his luck  before his is stuck with an
assumed disaster stuck in the hole.

At 11:49 AM 1/17/2019, you wrote:
You don't want to have to extract a broken tap.
Been there - suffered the pain.

Dave









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