1/4"-20 tap calls for 0.201" tap drill (13/64")

Into a steel 1/8" panel, tap is hard enough to turn that handles flex
:-(

Is that normal, or do I need to go up one or more drill sizes?

...Jim Thompson
--
| James E.Thompson, CTO | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.

"Jim Thompson" wrote in
message ...
1/4"-20 tap calls for 0.201" tap drill (13/64")

Into a steel 1/8" panel, tap is hard enough to turn that handles flex
:-(

Is that normal, or do I need to go up one or more drill sizes?

...Jim Thompson
--
| James E.Thompson, CTO | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.


Measure the core diameter of the tap and go down a bit for eccentricity and
general wobbles. Alternately, try your larger drill on a scrap piece, tap
the hole and then inspect it with a magnifier - if the threads are
flat-topped you've gone too far.

Chris

"Jim Thompson" wrote in
message ...
1/4"-20 tap calls for 0.201" tap drill (13/64")

Into a steel 1/8" panel, tap is hard enough to turn that handles flex
:-(

Is that normal, or do I need to go up one or more drill sizes?

...Jim Thompson

Do you have time to fight a broken tap out of the steel?
Been there, done that, don't like it!
Does the connection need all the strength of full threads?
If not, drill the hole larger.
If you don't drill the hole larger, at least use a good quality,
sharp tap, there is a big difference.
Either way, do use a proper lubricant.
I'll be away, and won't bother you while your doing this,
tell your wife to go away too!
Mike

PS. Most of my experience is with 4-40, 6-32, and 8-32 in aluminum.
I phased out the 4-40 without any regrets.

"Jim Thompson"
wrote in message ...
1/4"-20 tap calls for 0.201" tap drill (13/64")

Into a steel 1/8" panel, tap is hard enough to turn that handles flex
:-(

Is that normal, or do I need to go up one or more drill sizes?

...Jim Thompson

The 0.201 (13/64") is for softer materials. You want
to go to a 7/32" drill for harder materials. Also, you
have to decide if you want 75% or 50% threads.

I was in manufacturing for 25+ years.

Bill

"amdx" wrote in message
...

"Jim Thompson" wrote in
message ...
1/4"-20 tap calls for 0.201" tap drill (13/64")

Into a steel 1/8" panel, tap is hard enough to turn that handles flex
:-(

Is that normal, or do I need to go up one or more drill sizes?

...Jim Thompson

Do you have time to fight a broken tap out of the steel?
Been there, done that, don't like it!
Does the connection need all the strength of full threads?
If not, drill the hole larger.
If you don't drill the hole larger, at least use a good quality,
sharp tap, there is a big difference.
Either way, do use a proper lubricant.

You can't beat PTFE lubricants - slick50 or Finish line grease from a
bicycle shop.

On Sat, 10 Oct 2009 10:11:16 -0700, Jim Thompson
wrote:

1/4"-20 tap calls for 0.201" tap drill (13/64")

Into a steel 1/8" panel, tap is hard enough to turn that handles flex
:-(

Is that normal, or do I need to go up one or more drill sizes?

---
IME it's not normal.

As someone else suggested, make sure your tap is sharp and use lube.

If you haven't done any tapping in a while, it may be that the tap isn't
being held normal to the panel when it starts biting into the metal,
which can cause it to bind up.

In order to make that go away, get or make a "tapping block" which is
nothing more than a block with a 1/4" hole drilled through it
perpendicular to the face being drilled, hold it against the panel,
insert the tap into the hole and start the tap into the panel that way.

Works great!

JF

Jim Thompson wrote:

1/4"-20 tap calls for 0.201" tap drill (13/64")

Into a steel 1/8" panel, tap is hard enough to turn that handles flex
:-(

Is that normal, or do I need to go up one or more drill sizes?


...Jim Thompson

Are you using lube ? Soap is Ok.

--
Best Regards:
Baron.

Jim Thompson wrote:
1/4"-20 tap calls for 0.201" tap drill (13/64")

Into a steel 1/8" panel, tap is hard enough to turn that handles flex
:-(

Is that normal, or do I need to go up one or more drill sizes?

...Jim Thompson

Are you using cutting oil?

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal
ElectroOptical Innovations
55 Orchard Rd
Briarcliff Manor NY 10510
845-480-2058
hobbs at electrooptical dot net
http://electrooptical.net

"Jim Thompson" wrote in
message ...
1/4"-20 tap calls for 0.201" tap drill (13/64")

Into a steel 1/8" panel, tap is hard enough to turn that handles flex
:-(

Is that normal, or do I need to go up one or more drill sizes?

...Jim Thompson
--


You need some cutting oil, Kerosene or plain oil will do.

Cheers

On Sat, 10 Oct 2009 20:17:48 +0100, "ian field"
wrote:


"amdx" wrote in message
. ..

"Jim Thompson" wrote in
message ...
1/4"-20 tap calls for 0.201" tap drill (13/64")

Into a steel 1/8" panel, tap is hard enough to turn that handles flex
:-(

Is that normal, or do I need to go up one or more drill sizes?

...Jim Thompson

Do you have time to fight a broken tap out of the steel?
Been there, done that, don't like it!
Does the connection need all the strength of full threads?
If not, drill the hole larger.
If you don't drill the hole larger, at least use a good quality,
sharp tap, there is a big difference.
Either way, do use a proper lubricant.

You can't beat PTFE lubricants - slick50 or Finish line grease from a
bicycle shop.


Good idea! When I went out to get a larger bit, I bought a vanadium
tap :-)

...Jim Thompson
--
| James E.Thompson, CTO | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.

On Sat, 10 Oct 2009 14:20:54 -0500, John Fields
wrote:

On Sat, 10 Oct 2009 10:11:16 -0700, Jim Thompson
wrote:

1/4"-20 tap calls for 0.201" tap drill (13/64")

Into a steel 1/8" panel, tap is hard enough to turn that handles flex
:-(

Is that normal, or do I need to go up one or more drill sizes?

---
IME it's not normal.

As someone else suggested, make sure your tap is sharp and use lube.

If you haven't done any tapping in a while, it may be that the tap isn't
being held normal to the panel when it starts biting into the metal,
which can cause it to bind up.

In order to make that go away, get or make a "tapping block" which is
nothing more than a block with a 1/4" hole drilled through it
perpendicular to the face being drilled, hold it against the panel,
insert the tap into the hole and start the tap into the panel that way.

Works great!

JF

Really good idea! When I can, I use my drill press to get a vertical
start. In this case, it's free-hand, so your "tapping block" is a
SUPER idea! Thanks!

...Jim Thompson
--
| James E.Thompson, CTO | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.

On Sat, 10 Oct 2009 16:01:32 -0400, Phil Hobbs
wrote:

Jim Thompson wrote:
1/4"-20 tap calls for 0.201" tap drill (13/64")

Into a steel 1/8" panel, tap is hard enough to turn that handles flex
:-(

Is that normal, or do I need to go up one or more drill sizes?

...Jim Thompson

Are you using cutting oil?

Cheers

Phil Hobbs

Of course not! I'm an EE :-( But I will ;-)

...Jim Thompson
--
| James E.Thompson, CTO | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.

On Sat, 10 Oct 2009 10:11:16 -0700, Jim Thompson
wrote:

1/4"-20 tap calls for 0.201" tap drill (13/64")

Into a steel 1/8" panel, tap is hard enough to turn that handles flex
:-(

Is that normal, or do I need to go up one or more drill sizes?

...Jim Thompson

What lubricant are you using? And is the tap sharp?

Jim Thompson wrote:

1/4"-20 tap calls for 0.201" tap drill (13/64")

Into a steel 1/8" panel, tap is hard enough to turn that handles flex
:-(

Is that normal, or do I need to go up one or more drill sizes?

...Jim Thompson
#7 bit.

I use my small cordless black&decker 3/8 drill in slip mode
around 10 to drive the tap in, when it jams and the drill
chatters, reverse it and then reenter.
I do this all the time when making enclosure mounts etc..


P.S.
If you don't have drill&tap oil around, use D-40 and
use a start (tapered tip) tap not a bottom tap.

Jim Thompson wrote in
:

You can't beat PTFE lubricants - slick50 or Finish line grease from a
bicycle shop.

Good idea! When I went out to get a larger bit, I bought a vanadium
tap :-)
...Jim Thompson

If you are doing through holes, what you really want is a "gun" tap.
These push the chips out in front of the tap, so you don't have to do the
"forward 3/4 turn, back up 1/4 turn" routine to bust off the chips. They
just corkscrew out ahead of the tap.

A combination of:

1) lube

2) a guide block

3) a high quality gun tap

and you will be amazed at how easy it is to tap holes.

Doug White

On Sat, 10 Oct 2009 10:11:16 -0700, Jim Thompson
wrote:

1/4"-20 tap calls for 0.201" tap drill (13/64")

Into a steel 1/8" panel, tap is hard enough to turn that handles flex
:-(

Is that normal, or do I need to go up one or more drill sizes?

...Jim Thompson

1/4 - 20 through a mere 1/8 hole is too coarse a thread for that little
thickness. Use a #10 or a metric.

Also, tapping a hole has a bit of art to it. If you do not know the
limits of the metals the handles and taps, etc. are made of, you will not
know the tricks of performing the task, like the one where you only turn
a 1/4 turn or so at a time, and then back off and then go back in, and
you slowly work the tap, not attempt to make the turns all in one fell
swoop, and yes, some sort of lube is needed.

If you insist on the 1/4 - 20, then you can use the edges of the drill
to open up the hole a little bit. Makes the tapped hole a bit looser as
well, however.

Ideally, a panel that thin for a hole and subsequent bolt that size
should get a boss welded onto the back side of the hole so that the
number of threads is increased You should tap the boss first as it will
harden up when welded, and then you chase the tap back down through the
hole again after it has cooled.

1/4 - 20 can hold a pretty big load. Surely you could use a smaller
fastener, like a #10 or such.

Jim Thompson wrote:
1/4"-20 tap calls for 0.201" tap drill (13/64")

Into a steel 1/8" panel, tap is hard enough to turn that handles flex
:-(

Is that normal, or do I need to go up one or more drill sizes?

...Jim Thompson
Here are the specs from the Morse Machinist's Practical Guide (1961)
P.37: Size of screw 0.2500, body drill 17/64, size or number of drill
for percent of full thread: 100% #13, 80% #8, 75% #7, 70% #6, 60% #4,
50% #3. Recommended sizes: for monel metal, high speed steel 50-60% #4;
for bronze, tool steel, drop forged, stainless, nickel steel, copper,
cast steel 60-70% #6; for mild steel, aluminum, cast brass, cast iron
70-75% #7; and for sheet brass, sheet nickel, duraluminum, fiber,
babbit, white metal, hard rubber 75-80% #8.

#7 is 0.2010 which conforms to 75% of full thread from the chart
above and seems to conform to the recommended size (mild steel).
13/64 _is_ "one step" higher at 0.2031, so i would say go another
step to #6 0.2040 (next one is #5 0.2055 and then #4 0.2090).

amdx wrote:
"Jim Thompson" wrote in
message ...
1/4"-20 tap calls for 0.201" tap drill (13/64")

Into a steel 1/8" panel, tap is hard enough to turn that handles flex
:-(

Is that normal, or do I need to go up one or more drill sizes?

...Jim Thompson

Do you have time to fight a broken tap out of the steel?
Been there, done that, don't like it!
Does the connection need all the strength of full threads?
If not, drill the hole larger.
If you don't drill the hole larger, at least use a good quality,
sharp tap, there is a big difference.
Either way, do use a proper lubricant.
I'll be away, and won't bother you while your doing this,
tell your wife to go away too!
Mike

PS. Most of my experience is with 4-40, 6-32, and 8-32 in aluminum.
I phased out the 4-40 without any regrets.




I nominally use 2-56, 4-40, 6-32; sometimes 8-32, on rare occasion
10-32 then 10-24 and lastly 1/4-20 (been ages since i had to do a lot of
work using 1/4-28 and it was in steel and i may have used 70% percent of
full thread - over 40 years ago).
On all of the common stuff mentioned, i use 75% percent of full
thread since the hardest material i work with is aluminum.

Robert Baer wrote in
net:
snip
I nominally use 2-56, 4-40, 6-32; sometimes 8-32, on rare occasion
10-32 then 10-24 and lastly 1/4-20 (been ages since i had to do a lot
of work using 1/4-28 and it was in steel and i may have used 70%
percent of full thread - over 40 years ago).
On all of the common stuff mentioned, i use 75% percent of full
thread since the hardest material i work with is aluminum.

One note: 6-32 is the worst thread to tap. The ratio of the metal you
are removing to the root diamter of the tap is the largest, and they are
very easy to break if you aren't careful. A good tap block will help a
lot. For 1/4-20, you can make your own. If you do a lot of tapping, do
yourself a favor & get a commercial guide block or guided tap wrench.
There are several to choose from. For electronics work where you
frequently need to get into small spaces, I prefer one with removable
sleeves, but the one I have doesn't appear to be available anymore.
Here's a collection of tapping tools, including an inexpensive block:

http://tool.wttool.com/tools/Tap%20Guide

Here's one that looks like it will work well in tight spots, and has a V-
groove on the bottom for tapping round stock:

http://littlemachineshop.com/product...ProductID=3427

Doug White

"John Fields" wrote in message
...
On Sat, 10 Oct 2009 10:11:16 -0700, Jim Thompson
wrote:

1/4"-20 tap calls for 0.201" tap drill (13/64")

Into a steel 1/8" panel, tap is hard enough to turn that handles flex
:-(

Is that normal, or do I need to go up one or more drill sizes?

---
IME it's not normal.

As someone else suggested, make sure your tap is sharp and use lube.

If you haven't done any tapping in a while, it may be that the tap isn't
being held normal to the panel when it starts biting into the metal,
which can cause it to bind up.

In order to make that go away, get or make a "tapping block" which is
nothing more than a block with a 1/4" hole drilled through it
perpendicular to the face being drilled, hold it against the panel,
insert the tap into the hole and start the tap into the panel that way.


For tapping blind holes there's another trick you can add to your toolbox.

Many years ago a TV science show demonstrated a new invention, plugs of wax
like lubricant (a bit like glue stick) that you cut to length and push into
a blind hole before running the tap in, as the tap runs into the hole it
forces the lubricant out through the flutes - no part of the cutting edge
escapes lubrication and the extruding lubricant pushes out the swarf.

A search on the web failed to find any examples so maybe the invention
didn't catch on, but you can get a similar effect by injecting the blind
hole with grease from a glue applicator syringe.

Probably a bit OTT for mild steel, but could be a life saver on tougher
metals.

"Archimedes' Lever" wrote in message
...
On Sat, 10 Oct 2009 10:11:16 -0700, Jim Thompson
wrote:

1/4"-20 tap calls for 0.201" tap drill (13/64")

Into a steel 1/8" panel, tap is hard enough to turn that handles flex
:-(

Is that normal, or do I need to go up one or more drill sizes?

...Jim Thompson

1/4 - 20 through a mere 1/8 hole is too coarse a thread for that little
thickness. Use a #10 or a metric.

Also, tapping a hole has a bit of art to it. If you do not know the
limits of the metals the handles and taps, etc. are made of, you will not
know the tricks of performing the task, like the one where you only turn
a 1/4 turn or so at a time, and then back off and then go back in, and
you slowly work the tap, not attempt to make the turns all in one fell
swoop, and yes, some sort of lube is needed.

If you insist on the 1/4 - 20, then you can use the edges of the drill
to open up the hole a little bit. Makes the tapped hole a bit looser as
well, however.

Ideally, a panel that thin for a hole and subsequent bolt that size
should get a boss welded onto the back side of the hole so that the
number of threads is increased You should tap the boss first as it will
harden up when welded, and then you chase the tap back down through the
hole again after it has cooled.

1/4 - 20 can hold a pretty big load. Surely you could use a smaller
fastener, like a #10 or such.

Can you get Taptite screws in that size?

On Sun, 11 Oct 2009 17:16:24 +0100, "ian field"
wrote:


"Archimedes' Lever" wrote in message
.. .
On Sat, 10 Oct 2009 10:11:16 -0700, Jim Thompson
wrote:

1/4"-20 tap calls for 0.201" tap drill (13/64")

Into a steel 1/8" panel, tap is hard enough to turn that handles flex
:-(

Is that normal, or do I need to go up one or more drill sizes?

...Jim Thompson

1/4 - 20 through a mere 1/8 hole is too coarse a thread for that little
thickness. Use a #10 or a metric.

Also, tapping a hole has a bit of art to it. If you do not know the
limits of the metals the handles and taps, etc. are made of, you will not
know the tricks of performing the task, like the one where you only turn
a 1/4 turn or so at a time, and then back off and then go back in, and
you slowly work the tap, not attempt to make the turns all in one fell
swoop, and yes, some sort of lube is needed.

If you insist on the 1/4 - 20, then you can use the edges of the drill
to open up the hole a little bit. Makes the tapped hole a bit looser as
well, however.

Ideally, a panel that thin for a hole and subsequent bolt that size
should get a boss welded onto the back side of the hole so that the
number of threads is increased You should tap the boss first as it will
harden up when welded, and then you chase the tap back down through the
hole again after it has cooled.

1/4 - 20 can hold a pretty big load. Surely you could use a smaller
fastener, like a #10 or such.

Can you get Taptite screws in that size?

That is a brand name, not a screw type. So, it is unfamiliar over
here.

Here, we have PEMs, and KEPs and the like.

On Sat, 10 Oct 2009 22:58:26 -0700, Archimedes' Lever
wrote:

On Sat, 10 Oct 2009 10:11:16 -0700, Jim Thompson
wrote:

1/4"-20 tap calls for 0.201" tap drill (13/64")

Into a steel 1/8" panel, tap is hard enough to turn that handles flex
:-(

Is that normal, or do I need to go up one or more drill sizes?

...Jim Thompson

1/4 - 20 through a mere 1/8 hole is too coarse a thread for that little
thickness. Use a #10 or a metric.

Also, tapping a hole has a bit of art to it. If you do not know the
limits of the metals the handles and taps, etc. are made of, you will not
know the tricks of performing the task, like the one where you only turn
a 1/4 turn or so at a time, and then back off and then go back in, and
you slowly work the tap, not attempt to make the turns all in one fell
swoop, and yes, some sort of lube is needed.

If you insist on the 1/4 - 20, then you can use the edges of the drill
to open up the hole a little bit. Makes the tapped hole a bit looser as
well, however.

Ideally, a panel that thin for a hole and subsequent bolt that size
should get a boss welded onto the back side of the hole so that the
number of threads is increased You should tap the boss first as it will
harden up when welded, and then you chase the tap back down through the
hole again after it has cooled.

---
These work fine without welding:

http://www.pemnet.com/fastening_products/pdf/cldata.pdf

Drill, press, done!

JF

On Sun, 11 Oct 2009 14:04:36 -0500, John Fields
wrote:

On Sat, 10 Oct 2009 22:58:26 -0700, Archimedes' Lever
wrote:

On Sat, 10 Oct 2009 10:11:16 -0700, Jim Thompson
wrote:

1/4"-20 tap calls for 0.201" tap drill (13/64")

Into a steel 1/8" panel, tap is hard enough to turn that handles flex
:-(

Is that normal, or do I need to go up one or more drill sizes?

...Jim Thompson

1/4 - 20 through a mere 1/8 hole is too coarse a thread for that little
thickness. Use a #10 or a metric.

Also, tapping a hole has a bit of art to it. If you do not know the
limits of the metals the handles and taps, etc. are made of, you will not
know the tricks of performing the task, like the one where you only turn
a 1/4 turn or so at a time, and then back off and then go back in, and
you slowly work the tap, not attempt to make the turns all in one fell
swoop, and yes, some sort of lube is needed.

If you insist on the 1/4 - 20, then you can use the edges of the drill
to open up the hole a little bit. Makes the tapped hole a bit looser as
well, however.

Ideally, a panel that thin for a hole and subsequent bolt that size
should get a boss welded onto the back side of the hole so that the
number of threads is increased You should tap the boss first as it will
harden up when welded, and then you chase the tap back down through the
hole again after it has cooled.

---
These work fine without welding:

http://www.pemnet.com/fastening_products/pdf/cldata.pdf

Drill, press, done!

JF

Well, a drill press, and usually a special press block to swage the
union together.

But yes, I mentioned PEMs in this thread elsewhere. They are great,
and the most common current solution employed.

Above a certain size though, you will still see welded bolsterings for
holes. You can remove the temper by re-heating it with a torch after the
weldment is done and letting it cool slowly.

On Sun, 11 Oct 2009 14:04:36 -0500, John Fields
wrote:

On Sat, 10 Oct 2009 22:58:26 -0700, Archimedes' Lever
wrote:

On Sat, 10 Oct 2009 10:11:16 -0700, Jim Thompson
wrote:

1/4"-20 tap calls for 0.201" tap drill (13/64")

Into a steel 1/8" panel, tap is hard enough to turn that handles flex
:-(

Is that normal, or do I need to go up one or more drill sizes?

...Jim Thompson

1/4 - 20 through a mere 1/8 hole is too coarse a thread for that little
thickness. Use a #10 or a metric.

Also, tapping a hole has a bit of art to it. If you do not know the
limits of the metals the handles and taps, etc. are made of, you will not
know the tricks of performing the task, like the one where you only turn
a 1/4 turn or so at a time, and then back off and then go back in, and
you slowly work the tap, not attempt to make the turns all in one fell
swoop, and yes, some sort of lube is needed.

If you insist on the 1/4 - 20, then you can use the edges of the drill
to open up the hole a little bit. Makes the tapped hole a bit looser as
well, however.

Ideally, a panel that thin for a hole and subsequent bolt that size
should get a boss welded onto the back side of the hole so that the
number of threads is increased You should tap the boss first as it will
harden up when welded, and then you chase the tap back down through the
hole again after it has cooled.

---
These work fine without welding:

http://www.pemnet.com/fastening_products/pdf/cldata.pdf

Drill, press, done!

JF

Well, a drill press, and usually a special press block to swage the
union together.

But yes, I mentioned PEMs in this thread elsewhere. They are great,
and the most common current solution employed.

Above a certain size though, you will still see welded bolsterings for
holes. You can remove the temper by re-heating it with a torch after the
weldment is done and letting it cool slowly.

Doug White wrote:
Robert Baer wrote in
net:
snip
I nominally use 2-56, 4-40, 6-32; sometimes 8-32, on rare occasion
10-32 then 10-24 and lastly 1/4-20 (been ages since i had to do a lot
of work using 1/4-28 and it was in steel and i may have used 70%
percent of full thread - over 40 years ago).
On all of the common stuff mentioned, i use 75% percent of full
thread since the hardest material i work with is aluminum.

One note: 6-32 is the worst thread to tap. The ratio of the metal you
are removing to the root diamter of the tap is the largest, and they are
very easy to break if you aren't careful. A good tap block will help a
lot. For 1/4-20, you can make your own. If you do a lot of tapping, do
yourself a favor & get a commercial guide block or guided tap wrench.
There are several to choose from. For electronics work where you
frequently need to get into small spaces, I prefer one with removable
sleeves, but the one I have doesn't appear to be available anymore.
Here's a collection of tapping tools, including an inexpensive block:

http://tool.wttool.com/tools/Tap%20Guide

Here's one that looks like it will work well in tight spots, and has a V-
groove on the bottom for tapping round stock:

http://littlemachineshop.com/product...ProductID=3427

Doug White


6-32 is the size i work with the most; never had a problem.
But i have broken a few 2-45 taps (they are delicate).

"Archimedes' Lever" wrote in message
...
On Sun, 11 Oct 2009 17:16:24 +0100, "ian field"
wrote:


"Archimedes' Lever" wrote in message
. ..
On Sat, 10 Oct 2009 10:11:16 -0700, Jim Thompson
wrote:

1/4"-20 tap calls for 0.201" tap drill (13/64")

Into a steel 1/8" panel, tap is hard enough to turn that handles flex
:-(

Is that normal, or do I need to go up one or more drill sizes?

...Jim Thompson

1/4 - 20 through a mere 1/8 hole is too coarse a thread for that little
thickness. Use a #10 or a metric.

Also, tapping a hole has a bit of art to it. If you do not know the
limits of the metals the handles and taps, etc. are made of, you will
not
know the tricks of performing the task, like the one where you only turn
a 1/4 turn or so at a time, and then back off and then go back in, and
you slowly work the tap, not attempt to make the turns all in one fell
swoop, and yes, some sort of lube is needed.

If you insist on the 1/4 - 20, then you can use the edges of the drill
to open up the hole a little bit. Makes the tapped hole a bit looser as
well, however.

Ideally, a panel that thin for a hole and subsequent bolt that size
should get a boss welded onto the back side of the hole so that the
number of threads is increased You should tap the boss first as it will
harden up when welded, and then you chase the tap back down through the
hole again after it has cooled.

1/4 - 20 can hold a pretty big load. Surely you could use a smaller
fastener, like a #10 or such.

Can you get Taptite screws in that size?

That is a brand name, not a screw type. So, it is unfamiliar over
here.

Here, we have PEMs, and KEPs and the like.

A search for "pem" comes up with punched in threaded inserts, "KEP" produces
no relevant results.

Searching "taptite USA" finds a number of suppliers, sheet as thin as 1/8"
might be a bit tricky with taptites, normal industry practice would be to
drill the hole small and punch form the hole to the tapping size.

On Tue, 13 Oct 2009 15:12:37 +0100, "ian field"
wrote:


"Archimedes' Lever" wrote in message
.. .
On Sun, 11 Oct 2009 17:16:24 +0100, "ian field"
wrote:


"Archimedes' Lever" wrote in message
...
On Sat, 10 Oct 2009 10:11:16 -0700, Jim Thompson
wrote:

1/4"-20 tap calls for 0.201" tap drill (13/64")

Into a steel 1/8" panel, tap is hard enough to turn that handles flex
:-(

Is that normal, or do I need to go up one or more drill sizes?

...Jim Thompson

1/4 - 20 through a mere 1/8 hole is too coarse a thread for that little
thickness. Use a #10 or a metric.

Also, tapping a hole has a bit of art to it. If you do not know the
limits of the metals the handles and taps, etc. are made of, you will
not
know the tricks of performing the task, like the one where you only turn
a 1/4 turn or so at a time, and then back off and then go back in, and
you slowly work the tap, not attempt to make the turns all in one fell
swoop, and yes, some sort of lube is needed.

If you insist on the 1/4 - 20, then you can use the edges of the drill
to open up the hole a little bit. Makes the tapped hole a bit looser as
well, however.

Ideally, a panel that thin for a hole and subsequent bolt that size
should get a boss welded onto the back side of the hole so that the
number of threads is increased You should tap the boss first as it will
harden up when welded, and then you chase the tap back down through the
hole again after it has cooled.

1/4 - 20 can hold a pretty big load. Surely you could use a smaller
fastener, like a #10 or such.

Can you get Taptite screws in that size?

That is a brand name, not a screw type. So, it is unfamiliar over
here.

Here, we have PEMs, and KEPs and the like.

A search for "pem" comes up with punched in threaded inserts,

"KEP" produces
no relevant results.

"KEP" Nuts have an attached lock washer... convenient for working in
tight places. I always keep a box of 8-32 and 10-32 kep nuts on-hand.


Searching "taptite USA" finds a number of suppliers, sheet as thin as 1/8"
might be a bit tricky with taptites, normal industry practice would be to
drill the hole small and punch form the hole to the tapping size.


Up one drill size plus cutting oil did the trick. All 24 holes now
tapped ;-)

...Jim Thompson
--
| James E.Thompson, CTO | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.

Jim Thompson scrobe on the papyrus:

..
..
..
Up one drill size plus cutting oil did the trick. All 24 holes now
tapped ;-)

...Jim Thompson

I don't know if you can get these on your side of the pond, but I used
to get through tens of thousands of them every year.

http://www.avdel-global.com/en/produ...hin-sheet-nuts
ert.html

--

Remove "bot_confuser" to reply

If you're too open minded your brains will fall out.

On Tue, 13 Oct 2009 20:53:10 +0000 (UTC), "John B"
wrote:

Jim Thompson scrobe on the papyrus:

.
.
.
Up one drill size plus cutting oil did the trick. All 24 holes now
tapped ;-)

...Jim Thompson

I don't know if you can get these on your side of the pond, but I used
to get through tens of thousands of them every year.

http://www.avdel-global.com/en/produ...t-nutsert.html

Haven't seen them here quite like that, but those sure look nice!

...Jim Thompson
--
| James E.Thompson, CTO | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.

Up one drill size plus cutting oil did the trick. All 24 holes now
tapped ;-)


What the hell kind of locomotive are you BUILDING???

Jim

On Tue, 13 Oct 2009 18:33:05 -0500, flipper wrote:

On Tue, 13 Oct 2009 13:56:25 -0700, Jim Thompson
wrote:

On Tue, 13 Oct 2009 20:53:10 +0000 (UTC), "John B"
wrote:

Jim Thompson scrobe on the papyrus:

.
.
.
Up one drill size plus cutting oil did the trick. All 24 holes now
tapped ;-)

...Jim Thompson

I don't know if you can get these on your side of the pond, but I used
to get through tens of thousands of them every year.

http://www.avdel-global.com/en/produ...t-nutsert.html

Haven't seen them here quite like that, but those sure look nice!


Try these

http://www.pemnet.com/fastening_prod...tlas/#spintite


...Jim Thompson

I'm all done, just awaiting machined pieces to bolt on ;-)

...Jim Thompson
--
| James E.Thompson, CTO | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.

On Tue, 13 Oct 2009 19:31:26 -0500, flipper wrote:

On Tue, 13 Oct 2009 16:37:48 -0700, Jim Thompson
wrote:

On Tue, 13 Oct 2009 18:33:05 -0500, flipper wrote:

On Tue, 13 Oct 2009 13:56:25 -0700, Jim Thompson
wrote:

On Tue, 13 Oct 2009 20:53:10 +0000 (UTC), "John B"
wrote:

Jim Thompson scrobe on the papyrus:

.
.
.
Up one drill size plus cutting oil did the trick. All 24 holes now
tapped ;-)

...Jim Thompson

I don't know if you can get these on your side of the pond, but I used
to get through tens of thousands of them every year.

http://www.avdel-global.com/en/produ...t-nutsert.html

Haven't seen them here quite like that, but those sure look nice!


Try these

http://www.pemnet.com/fastening_prod...tlas/#spintite


...Jim Thompson

I'm all done, just awaiting machined pieces to bolt on ;-)

Yeah, I meant for future reference since you seemed to be saying you
couldn't get the others.


...Jim Thompson

I've learned about a lot of neat parts from this post. Thanks to all!

...Jim Thompson
--
| James E.Thompson, CTO | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.

On Tue, 13 Oct 2009 20:53:10 +0000 (UTC), "John B"
wrote:

Jim Thompson scrobe on the papyrus:

.
.
.
Up one drill size plus cutting oil did the trick. All 24 holes now
tapped ;-)

...Jim Thompson

I don't know if you can get these on your side of the pond, but I used
to get through tens of thousands of them every year.

http://www.avdel-global.com/en/produ...hin-sheet-nuts
ert.html

I have used something similar to the superserts.

Usually, a shop would swage a PEM on, and it would be tight, but that
same PEM is hard for the home shop owner to get in tight, so a hand
crimped version (several) had to be made. I know the 1/4 - 20 is
available but never used it. Ours was 1/4" hole, and drop in the insert
already threaded onto the swaging tool. and squeeze. The tool swages the
insert in place very tightly. The stuff was passing CSA back when they
threw things off their dock platform to 'test' it.

On Tue, 13 Oct 2009 14:50:00 -0700, "RST Engineering - JIm"
wrote:

Up one drill size plus cutting oil did the trick. All 24 holes now
tapped ;-)


What the hell kind of locomotive are you BUILDING???

Jim


1/8 inch panel. 24 1/4 - 20 holes. I'd say that #8 would work. #10
for certain.

Just think... 4 #10 screws holds in some pretty fat rack modules by
the ears.

If he was attaching something to the plate with one or two 1/4 - 20
screws, I could see it.

24 holes, however, likely makes it a lid for something.

We haven't heard the plate size though, so it could be a big Olympic
sized pool cover for all we know. He uses a crane to raise and lower it
on and off the pool. :-) (a sky crane).

That's where he brews his beer. :-)

On Tue, 13 Oct 2009 18:33:05 -0500, flipper wrote:

On Tue, 13 Oct 2009 13:56:25 -0700, Jim Thompson
wrote:

On Tue, 13 Oct 2009 20:53:10 +0000 (UTC), "John B"
wrote:

Jim Thompson scrobe on the papyrus:

.
.
.
Up one drill size plus cutting oil did the trick. All 24 holes now
tapped ;-)

...Jim Thompson

I don't know if you can get these on your side of the pond, but I used
to get through tens of thousands of them every year.

http://www.avdel-global.com/en/produ...t-nutsert.html

Haven't seen them here quite like that, but those sure look nice!


Try these

http://www.pemnet.com/fastening_prod...tlas/#spintite


...Jim Thompson

The AET / AEW type are what we used.

On Wed, 14 Oct 2009 00:30:09 -0700, Archimedes' Lever
wrote:

On Tue, 13 Oct 2009 14:50:00 -0700, "RST Engineering - JIm"
wrote:

Up one drill size plus cutting oil did the trick. All 24 holes now
tapped ;-)


What the hell kind of locomotive are you BUILDING???

Jim


1/8 inch panel. 24 1/4 - 20 holes. I'd say that #8 would work. #10
for certain.

Just think... 4 #10 screws holds in some pretty fat rack modules by
the ears.

---
Actually, only the bottom two are working.



JF