Drill depth vs. cut tap depth in blind hole

[Proctologically Violated©®]

Awl --

Given a desired tap depth, is there a formula for the drill depth?

Along those lines, here is a ditty I use for tapping.
R8, R9 establish the relationship between drill and tap depths in subroutine
L200, and get passed to the Z's in the drill/tap cycle, preserving the
relationship. This also minimizes the error of changing one, and not
changing the other.

I have chosen a drill depth 50% greater than the tap depth.
Normally, I would assign these numbers to V variables, and later pass those
on to R variables, but with no real calculations, this isn't really
necessary here.

Feel free to critique the tapping code, as I have no idea why shit is the
way it is, just that it works.

N13L200

N14#R8=.48' tap depth

N15#R9=1.5*R8' drill depth

N16M17

N21M30

N22( MAIN PROGRAM

N31M6T21( #21 DRILL

N32L201

N33G0X0Y0Z3.H21E2M3S1500

N34Z1.M8

N35Z0.1

N36G83G98R+0.1Z-R9F7.5Q0.45( <------ R9

N38G80

N39(

N40M6T20( TAP, 10-32

N41L201

N42G0X0Y0Z3.E1H20

N43Z1.G4P500

N44G0G90G80M90S2000.2M5

N45G84.2

N46Z0.4M8

N47G84.1G98R+0.1Z-R8S1000.2F31.25( <--------- R8

N49G80M9

N50Y4.

N51M6T2

[Garlicdude]

Post by Proctologically Violated©®
Awl --
Given a desired tap depth, is there a formula for the drill depth?

http://www.rose-training.com/tandp/aug06.htm

[BottleBob]

Post by Proctologically Violated©®
Awl --
Given a desired tap depth, is there a formula for the drill depth?
Along those lines, here is a ditty I use for tapping.
R8, R9 establish the relationship between drill and tap depths in subroutine
L200, and get passed to the Z's in the drill/tap cycle, preserving the
relationship. This also minimizes the error of changing one, and not
changing the other.
I have chosen a drill depth 50% greater than the tap depth.
Normally, I would assign these numbers to V variables, and later pass those
on to R variables, but with no real calculations, this isn't really
necessary here.
Feel free to critique the tapping code, as I have no idea why shit is the
way it is, just that it works.
N13L200
N14#R8=.48' tap depth
N15#R9=1.5*R8' drill depth
N16M17
N21M30
N22( MAIN PROGRAM
N31M6T21( #21 DRILL
N32L201
N33G0X0Y0Z3.H21E2M3S1500
N34Z1.M8
N35Z0.1
N36G83G98R+0.1Z-R9F7.5Q0.45( <------ R9
N38G80
N39(
N40M6T20( TAP, 10-32
N41L201
N42G0X0Y0Z3.E1H20
N43Z1.G4P500
N44G0G90G80M90S2000.2M5
N45G84.2
N46Z0.4M8
N47G84.1G98R+0.1Z-R8S1000.2F31.25( <--------- R8
N49G80M9
N50Y4.
N51M6T2

PV:

I generally make the cut tap depth 2/3 of the drill depth for blind
holes. Essentially identical to your drill depth being 50% greater
than your tap depth.

I've got a whole slew of "hooks" to pull threads out of blind holes,
from modified saw blades down to paper clips with small hooks on them.
Also have a series of air nozzles going down to .050" OD to try and
blow them out.

Trapped chips in blind holes is the ONE best reason for switching to a
form tap. Then you can run the form tap right down to near bottom, I
generally go down to the depth of the outer dia. of the drill's cutting
lips.
When engineers get crazy with their full thread depth callouts I'll
often modify form taps to cut full threads to within .030 of the
bottom of the hole (after helical milling the hole to get a flat
bottom). That last little bit usually has to be done by hand.

There's always the option of thread milling, no problem with trapped
chips, and you don't have to drill the hole much deeper than your
thread depth. Those puppies seem to cost about 10 times what a tap does
though. Snap a couple of those off and you'll be depressed for the
whole day. :)

[Black Dragon]

Post by BottleBob
I've got a whole slew of "hooks" to pull threads out of blind holes,
from modified saw blades down to paper clips with small hooks on them.

Crochet hooks. They're available in numerous sizes.

Store them next to the lipstick for sticky collets for a little feminine
touch in your tool box. I keep my silly putty for proofing mold
engraving in the same area too. :)

[Bipolar Bear]

Post by Black Dragon
Store them next to the lipstick for sticky collets for a little feminine
touch in your tool box.

Interestingly, I've found Vaseline to be much more useful than lipstick...

--

[Black Dragon]

Post by Bipolar Bear
Interestingly, I've found Vaseline to be much more useful than lipstick...

In that case, store them next to the Vaseline for sticky collets for a
little bi-curious touch in your tool box...

[BottleBob]

Post by Black Dragon

Post by BottleBob
I've got a whole slew of "hooks" to pull threads out of blind holes,
from modified saw blades down to paper clips with small hooks on them.

Crochet hooks. They're available in numerous sizes.

BD:

Well now, that's a real machining TIP that I've never heard before.
Someone should start making a list. <g>

Actually, thinking about it now I've got like a .125 Dia. stainless
rod that I've modified the end (which resembles a knitting needle tip),
that I use for yanking thread chips out of larger holes.

Post by Black Dragon
Store them next to the lipstick for sticky collets for a little feminine
touch in your tool box. I keep my silly putty for proofing mold
engraving in the same area too. :)

Have you ever found a machining related use for tampons? :)

[Black Dragon]

Post by BottleBob

Post by Black Dragon

Post by BottleBob
I've got a whole slew of "hooks" to pull threads out of blind holes,
from modified saw blades down to paper clips with small hooks on them.

Crochet hooks. They're available in numerous sizes.

Well now, that's a real machining TIP that I've never heard before.
Someone should start making a list. <g>

Count me out! I've had my fill of lits for a while. :)

Post by BottleBob
Actually, thinking about it now I've got like a .125 Dia. stainless
rod that I've modified the end (which resembles a knitting needle tip),
that I use for yanking thread chips out of larger holes.

Post by Black Dragon
Store them next to the lipstick for sticky collets for a little feminine
touch in your tool box. I keep my silly putty for proofing mold
engraving in the same area too. :)

Have you ever found a machining related use for tampons? :)

New? Or used? <g>

[BottleBob]

Post by Black Dragon

Post by BottleBob
Have you ever found a machining related use for tampons? :)

New? Or used? <g>

BD:

Yetch! I'll NEVER get that imagery out of my mind now. :(

[Cliff]

Post by BottleBob
Have you ever found a machining related use for tampons? :)

I spotted something the other day.
Lego bricks used to make "dams" about models
for casting.
Silicone rubbers are expensive as is time & effort & materials
to make dams.
IIRC They were casting molds of fossils.

[D Murphy]

Post by Cliff

Post by BottleBob
Have you ever found a machining related use for tampons? :)

I spotted something the other day.
Lego bricks used to make "dams" about models
for casting.
Silicone rubbers are expensive as is time & effort & materials
to make dams.
IIRC They were casting molds of fossils.

So you were there volunteering to be cast?

[Cliff]

Post by D Murphy

Post by Cliff

Post by BottleBob
Have you ever found a machining related use for tampons? :)

I spotted something the other day.
Lego bricks used to make "dams" about models
for casting.
Silicone rubbers are expensive as is time & effort & materials
to make dams.
IIRC They were casting molds of fossils.

So you were there volunteering to be cast?

Was it the silicone rubbers?

[D Murphy]

Post by Cliff

Post by D Murphy

Post by Cliff

Post by BottleBob
Have you ever found a machining related use for tampons? :)

I spotted something the other day.
Lego bricks used to make "dams" about models
for casting.
Silicone rubbers are expensive as is time & effort & materials
to make dams.
IIRC They were casting molds of fossils.

So you were there volunteering to be cast?

Was it the silicone rubbers?

Fossils. LOL.

[c***@lycos.com]

Post by BottleBob
Have you ever found a machining related use for tampons? :)

In the oil patch, a box of feminine napkins are usually around for soaking up blood from
an injury. As far as tampons, any drive by shooters near your shop? ;)

Wes

[BottleBob]

Post by c***@lycos.com

Post by BottleBob
Have you ever found a machining related use for tampons? :)

In the oil patch, a box of feminine napkins are usually around for soaking up blood from
an injury. As far as tampons, any drive by shooters near your shop? ;)

Wes:

Are you suggesting that tampons can be used to plug up gunshot wounds?
Sorry, we're not in a gangbanger drive by area, so I won't be able to
test this hypothesis any time soon. :)

[Black Dragon]

Post by BottleBob
Sorry, we're not in a gangbanger drive by area

Heh. You should come to Batavia NY. It's so bad here a heat packing 6
year old was recently found on his school bus. <g>

"6-year-old found with a loaded gun on a Batavia school bus Wednesday"
http://thedailynewsonline.com/articles/2008/12/18/news/4974618.txt

[BottleBob]

Post by Black Dragon

Post by BottleBob
Sorry, we're not in a gangbanger drive by area

Heh. You should come to Batavia NY. It's so bad here a heat packing 6
year old was recently found on his school bus. <g>

BD:

Cripes. Maybe there's an opportunity for an industrious entrepreneur
in the marketing of Kevlar T-shirts for grammar schoolers, eh?

[Randy Replogle]

Post by c***@lycos.com

Post by BottleBob
Have you ever found a machining related use for tampons? :)

In the oil patch, a box of feminine napkins are usually around for soaking up blood from
an injury. As far as tampons, any drive by shooters near your shop? ;)
Wes

Do you remember the old TV show "Combat"?
I was just a kid but recognized the "bandages" they pulled out of their
kits.
RR

[Randy]

Post by BottleBob
I've got a whole slew of "hooks" to pull threads out of blind holes,
from modified saw blades down to paper clips with small hooks on them.
Also have a series of air nozzles going down to .050" OD to try and
blow them out.
Trapped chips in blind holes is the ONE best reason for switching to a
form tap. Then you can run the form tap right down to near bottom, I
generally go down to the depth of the outer dia. of the drill's cutting
lips.

From James Harvey's book I use a drywall screw. Works even better if
you grind off the head and use them in a cordless drill. 1/4-20 or
bigger anyway.

Thank You,
Randy

Remove 333 from email address to reply.

[BottleBob]

Post by Randy
From James Harvey's book I use a drywall screw. Works even better if
you grind off the head and use them in a cordless drill. 1/4-20 or
bigger anyway.

Randy:

I made a cork-screw looking chip remover, a pain to make and didn't
work all that well anyway. Wish I had thought of the drywall screw
idea, sounds like a winner.

[Randy Replogle]

From James Harvey's book I use a drywall screw. Works even better if
you grind off the head and use them in a cordless drill. 1/4-20 or
bigger anyway.

I made a cork-screw looking chip remover, a pain to make and didn't work
all that well anyway. Wish I had thought of the drywall screw idea,
sounds like a winner.

It works ok but does anyone make them with a left-hand thread?
RR

[Garlicdude]

Post by Randy Replogle

Post by BottleBob

From James Harvey's book I use a drywall screw. Works even better if
you grind off the head and use them in a cordless drill. 1/4-20 or
bigger anyway.

I made a cork-screw looking chip remover, a pain to make and didn't
work all that well anyway. Wish I had thought of the drywall screw
idea, sounds like a winner.

It works ok but does anyone make them with a left-hand thread?
RR

Randy, How about running the drill in reverse?

Best,
Steve

[BottleBob]

Post by Garlicdude

Post by Randy Replogle

Post by BottleBob
I made a cork-screw looking chip remover, a pain to make and didn't
work all that well anyway. Wish I had thought of the drywall screw
idea, sounds like a winner.

It works ok but does anyone make them with a left-hand thread?
RR

Randy, How about running the drill in reverse?

GD:

Probably wouldn't work well. It would tend to PUSH the chips DOWN
rather than pull them up the thread spiral. Think corkscrew in reverse.

[Garlicdude]

Post by BottleBob

Post by Garlicdude

Post by Randy Replogle

Post by BottleBob
I made a cork-screw looking chip remover, a pain to make and didn't
work all that well anyway. Wish I had thought of the drywall screw
idea, sounds like a winner.

It works ok but does anyone make them with a left-hand thread?
RR

Randy, How about running the drill in reverse?

Probably wouldn't work well. It would tend to PUSH the chips DOWN
rather than pull them up the thread spiral. Think corkscrew in reverse.

Bob, Running in reverse would LIFT the chips up, but the screw wouldn't self
feed into the chips.

Best,
Steve

[Randy Replogle]

Post by Garlicdude
Bob, Running in reverse would LIFT the chips up, but the screw wouldn't
self feed into the chips.

"Lift" meaning chips/strings unscrewing themselves out of the hole?
Probably so. I was thinking about a left-handed screw biting screw into
the mess and unscrewing it. Instead of a right-hand screw running
backward to unscrew the mess, how about something like a phillips
screwdriver bit or maybe a drill blank with a left-hand drill type tip
or spade tip ground into it?
RR

[BottleBob]

Post by Garlicdude

Post by BottleBob

Post by Garlicdude
Randy, How about running the drill in reverse?

Probably wouldn't work well. It would tend to PUSH the chips DOWN
rather than pull them up the thread spiral. Think corkscrew in reverse.

GD:

Right after I hit the send button I thought GD was probably joking and
I took him too literally.

Post by Garlicdude
Bob, Running in reverse would LIFT the chips up, but the screw wouldn't
self feed into the chips.

Now from THIS response it seems likely that while you have me on your
hook, you're wiggling it a little to watch me squirm.

But for your "squirm" watching pleasure, I'll continue. :)

If you take a regular right-hand screw and stick your thumbnail in
the thread (simulating a chip), and screw it clockwise (like screwing
it INTO a hole), your thumbnail will travel UP the screw like a chip
would. But if you turn it in reverse (like UNscrewing it) your
thumbnail will move DOWNWARD.

Now having said THAT, IF you could displace the chips sideways INTO
the existing threads you "might" get a lifting assist by the threads
themselves. BUT, thread chips are usually crammed down in the hole
below where the threads end, so that's an ify situation.

I don't have any access to any chips, threaded holes, screws, or
anything else right now to actually test this.

[Garlicdude]

Post by BottleBob

Post by Garlicdude

Post by BottleBob

Post by Garlicdude
Randy, How about running the drill in reverse?

Probably wouldn't work well. It would tend to PUSH the chips
DOWN rather than pull them up the thread spiral. Think corkscrew in
reverse.

Right after I hit the send button I thought GD was probably joking
and I took him too literally.

Post by Garlicdude
Bob, Running in reverse would LIFT the chips up, but the screw
wouldn't self feed into the chips.

Now from THIS response it seems likely that while you have me on
your hook, you're wiggling it a little to watch me squirm.
But for your "squirm" watching pleasure, I'll continue. :)
If you take a regular right-hand screw and stick your thumbnail in
the thread (simulating a chip), and screw it clockwise (like screwing it
INTO a hole), your thumbnail will travel UP the screw like a chip
would. But if you turn it in reverse (like UNscrewing it) your
thumbnail will move DOWNWARD.
Now having said THAT, IF you could displace the chips sideways INTO
the existing threads you "might" get a lifting assist by the threads
themselves. BUT, thread chips are usually crammed down in the hole
below where the threads end, so that's an ify situation.
I don't have any access to any chips, threaded holes, screws, or
anything else right now to actually test this.

Bob, Not trying to hook you, but watching the screw flights on a large wood
screw it appeared to me that the flights would lift chips out of the hole.


Best,
Steve

[BottleBob]

Post by Garlicdude
Bob, Not trying to hook you, but watching the screw flights on a large
wood screw it appeared to me that the flights would lift chips out of
the hole.

Steve:

I think your spell checker turned fluted into flights. But no matter.
A wood screw's flutes probably would tend to lift chips and debris -
as long as it was turning clockwise viewed from the top.

A post hole auger is kinda like a large wood screw, watch the
following video - the tractor not the guy in front. Now imagine if the
auger was turning the opposite direction - do you think it would it
work as well?

[b***@aol.com]

Post by BottleBob
I think your spell checker turned fluted into flights.

<snip>

Post by BottleBob
A post hole auger is kinda like a large wood screw,

And on an auger it's flight/s not flutes.

http://www.clearcreekassociates.com/wordarchive/augerflights.htm

Tom

[BottleBob]

Post by b***@aol.com

I think your spell checker turned flutes into flights.

<snip>

A post hole auger is kinda like a large wood screw,

And on an auger it's flight/s not flutes.
http://www.clearcreekassociates.com/wordarchive/augerflights.htm

Tom:

Now that's cool, I didn't know that.

But it seems the spaces between the flights are still called flutes.
So an auger has flutes & flights.

[Cliff]

Post by BottleBob
When engineers get crazy with their full thread depth callouts I'll
often modify form taps

I'll again point out that form tapping has to explicitly be allowed
on the print or similar in most cases.

Post by BottleBob
to cut full threads to within .030 of the
bottom of the hole (after helical milling the hole to get a flat
bottom). That last little bit usually has to be done by hand.

You don't believe in serial taps?

[BottleBob]

Post by Cliff

Post by BottleBob
to cut full threads to within .030 of the
bottom of the hole (after helical milling the hole to get a flat
bottom). That last little bit usually has to be done by hand.

You don't believe in serial taps?

Cliff:

By "serial taps" do you mean beginning with a starting tap, then
proceeding with a plug tap, the finishing with a bottom tap?

[Dave B]

Post by BottleBob

Post by Cliff

Post by BottleBob
to cut full threads to within .030 of the
bottom of the hole (after helical milling the hole to get a flat
bottom). That last little bit usually has to be done by hand.

You don't believe in serial taps?

By "serial taps" do you mean beginning with a starting tap, then
proceeding with a plug tap, the finishing with a bottom tap?

LOL.......have a good hoilday.


Dave B

[Garlicdude]

Post by BottleBob

Post by Cliff

to cut full threads to within .030 of the bottom of the hole (after
helical milling the hole to get a flat bottom). That last little bit
usually has to be done by hand.

You don't believe in serial taps?

By "serial taps" do you mean beginning with a starting tap, then
proceeding with a plug tap, the finishing with a bottom tap?

Bob, Bet he meant spiral flute taps

Best,
Steve

[Dave B]

Post by Garlicdude

Post by BottleBob

Post by Cliff

to cut full threads to within .030 of the bottom of the hole (after
helical milling the hole to get a flat bottom). That last little bit
usually has to be done by hand.

You don't believe in serial taps?

By "serial taps" do you mean beginning with a starting tap, then
proceeding with a plug tap, the finishing with a bottom tap?

Bob, Bet he meant spiral flute taps
Best,
Steve

Nah, he meant three different size taps, undersized,intermediate,and
finish size.

Dave B

[Bipolar Bear]

Post by Dave B

Post by Garlicdude

Post by BottleBob

Post by Cliff

to cut full threads to within .030 of the bottom of the hole (after
helical milling the hole to get a flat bottom). That last little bit
usually has to be done by hand.

You don't believe in serial taps?

By "serial taps" do you mean beginning with a starting tap, then
proceeding with a plug tap, the finishing with a bottom tap?

Bob, Bet he meant spiral flute taps
Best,
Steve

Nah, he meant three different size taps, undersized,intermediate,and
finish size.

H3, Sti, Twinsert plus

http://www.bollhoff-china.com/web/germany/en/web.nsf/HTML/hcr_twinsert.html

--



--

[Cliff]

Post by Garlicdude
Bob, Bet he meant spiral flute taps

Nope.

[Cliff]

Post by BottleBob

Post by Cliff

Post by BottleBob
to cut full threads to within .030 of the
bottom of the hole (after helical milling the hole to get a flat
bottom). That last little bit usually has to be done by hand.

You don't believe in serial taps?

By "serial taps" do you mean beginning with a starting tap, then
proceeding with a plug tap, the finishing with a bottom tap?

That's what I had intended though it seems that "serial tap"
has another meaning too.

http://nzdl.sadl.uleth.ca/cgi-bin/library?e=d-00000-00---off-0gtz--00-0--0-10-0---0---0prompt-10---4-------0-1l--11-en-50---20-about---00-0-1-00-0-0-11-1-0utfZz-8-00&a=d&cl=CL1.3&d=HASH01810ed5f215cd7f058531e8.4

[BottleBob]

On Wed, 24 Dec 2008 09:59:46 -0800, BottleBob

Post by BottleBob

On Mon, 22 Dec 2008 09:33:32 -0800, BottleBob

to cut full threads to within .030 of the bottom of the hole
(after helical milling the hole to get a flat bottom). That
last little bit usually has to be done by hand.

You don't believe in serial taps?

By "serial taps" do you mean beginning with a starting tap, then
proceeding with a plug tap, the finishing with a bottom tap?

That's what I had intended though it seems that "serial tap" has
another meaning too.

Cliff:

First: That would be fine if you were hand tapping a hole in inconel,
but it makes it hard if you were trying to rigid tap with your CNC in
the same hole with three different taps in your carousel. It'd be very
difficult to align the three taps accurately to follow in the same
thread - and if one of them slipped...
Second: Bottom taps usually are tapered about 1-2 thread on the end.
So on a 1/4-20 tap your pitch would be .050 - the incomplete threads
would be .050-.100 from the bottom. So you'd still have to modify a
tap to get complete threads within .030 of the bottom.

[Cliff]

Post by BottleBob
Second: Bottom taps usually are tapered about 1-2 thread on the end.
So on a 1/4-20 tap your pitch would be .050 - the incomplete threads
would be .050-.100 from the bottom. So you'd still have to modify a
tap to get complete threads within .030 of the bottom.

I did not say you could have full thread all the way down.

BTW, Think about it ... some mentioned getting the chips out of the
hole ... in many cases this may be no value added, just cost.
Pack 'em in the bottom, leave some still attached, don't
start electrolytic corrosion or rust ...
For many needs (bolt once & forget) that might be just fine.
Get a call out on the print <g>.

[BottleBob]

Post by Cliff

Post by BottleBob
Second: Bottom taps usually are tapered about 1-2 thread on the end.
So on a 1/4-20 tap your pitch would be .050 - the incomplete threads
would be .050-.100 from the bottom. So you'd still have to modify a
tap to get complete threads within .030 of the bottom.

I did not say you could have full thread all the way down.
to cut full threads to within .030 of the

Post by BottleBob
bottom of the hole (after helical milling the hole to get a flat
bottom). That last little bit usually has to be done by hand.

Cliff replied:
You don't believe in serial taps?


It appeared you were replying to my comment about cutting full threads
to within .030 of the bottom. Otherwise why quote my comment before
your reply about serial taps?

Post by Cliff
BTW, Think about it ... some mentioned getting the chips out of the
hole ... in many cases this may be no value added, just cost.
Pack 'em in the bottom, leave some still attached, don't
start electrolytic corrosion or rust ...

I'm not so sure it's a hot idea to leave steel chips and/or coolant in
the bottom of a hole. You just mentioned electrolytic corrosion, and
such corrosion could very well extend to the end of the bolt and into
the threads as well.

[Cliff]

Post by BottleBob
I'm not so sure it's a hot idea to leave steel chips and/or coolant in
the bottom of a hole. You just mentioned electrolytic corrosion, and
such corrosion could very well extend to the end of the bolt and into
the threads as well.

If bolt of same material little risk of electrolytic corrosion,
if oil was used as a cuting fluid little risk, lf electrolytic corrosion
is self-limiting, if hole dry little risk .....

[BottleBob]

Post by Cliff

Post by BottleBob
I'm not so sure it's a hot idea to leave steel chips and/or coolant in
the bottom of a hole. You just mentioned electrolytic corrosion, and
such corrosion could very well extend to the end of the bolt and into
the threads as well.

If bolt of same material little risk of electrolytic corrosion,
if oil was used as a cuting fluid little risk, lf electrolytic corrosion
is self-limiting, if hole dry little risk .....

Cliff:

That's a lot of *IF's*, there Cliff. Don't you think it would be
safer and more advantageous to forestall any possible future problems
by just removing any chips and coolant out of your tapped holes?

[c***@lycos.com]

Post by BottleBob
By "serial taps" do you mean beginning with a starting tap, then
proceeding with a plug tap, the finishing with a bottom tap?

Who knows what Cliff ment but don't they make ACME taps that are used sequentially
(serial) to make part of the thread depth at a time?

Wes

[BottleBob]

Post by c***@lycos.com

Post by BottleBob
By "serial taps" do you mean beginning with a starting tap, then
proceeding with a plug tap, the finishing with a bottom tap?

Who knows what Cliff ment but don't they make ACME taps that are used sequentially
(serial) to make part of the thread depth at a time?

Wes:

=============================================================
http://www.bctus.com/tech_tap_main_types.html

SERIAL TAPS

Serial taps comprise of one or more undersized roughing taps which
remove most of the material before final sizing with a finishing tap.

Some reasons for using serial taps are:

(a) The roughness of the material being tapped.

(b) The amount of material to be removed could cause swarf choking
with a single tap.

(c) The very small tolerance on pitch diameter.

(d) An extremely good finish required.
=============================================================

But ya know, I don't recall ever using any "serial taps" using this
definition. Like everyone, I've used GH-1 through GH-8 taps, but not a
SET of taps to creep up on the pitch diameter of ONE hole.

Learn something everyday.

[Garlicdude]

Post by BottleBob

Post by c***@lycos.com

Post by BottleBob
By "serial taps" do you mean beginning with a starting tap, then
proceeding with a plug tap, the finishing with a bottom tap?

Who knows what Cliff ment but don't they make ACME taps that are used sequentially
(serial) to make part of the thread depth at a time?

=============================================================
http://www.bctus.com/tech_tap_main_types.html
SERIAL TAPS
Serial taps comprise of one or more undersized roughing taps which
remove most of the material before final sizing with a finishing tap.
(a) The roughness of the material being tapped.
(b) The amount of material to be removed could cause swarf choking
with a single tap.
(c) The very small tolerance on pitch diameter.
(d) An extremely good finish required.
=============================================================
But ya know, I don't recall ever using any "serial taps" using this
definition. Like everyone, I've used GH-1 through GH-8 taps, but not a
SET of taps to creep up on the pitch diameter of ONE hole.
Learn something everyday.

Bob/Wes, I've used a series of 2 taps on acme threads in the past. Have never
used "serial" taps on 60 deg. included angle threads.

Best,
Steve

[J. Nielsen]

Post by BottleBob
But ya know, I don't recall ever using any "serial taps" using this
definition. Like everyone, I've used GH-1 through GH-8 taps, but not a
SET of taps to creep up on the pitch diameter of ONE hole.

Back in my apprentic days when *a lot* of threads were cut by hand,
we used special taps in sets of three: The start tap had a non-cutting
cylindrical guide part which helped aligning the tap, and the thread profile
had the top of the teeth relieved. #2 tap had the same profile, but without
guide. #3 cut to full profile.

Normally we would just skip #2 (no jokes, please!)

[Cliff]

Post by c***@lycos.com

Post by BottleBob
By "serial taps" do you mean beginning with a starting tap, then
proceeding with a plug tap, the finishing with a bottom tap?

Who knows what Cliff ment

I posted a link to some serial taps <g>.

[Cliff]

Post by BottleBob
Trapped chips in blind holes is the ONE best reason for switching to a
form tap.

Or a horizontal or a magnet or a different style of tap ...

[BottleBob]

Post by Cliff

Post by BottleBob
Trapped chips in blind holes is the ONE best reason for switching to a
form tap.

Or a horizontal or a magnet or a different style of tap ...

Cliff:

If the chips from tapping are jamming in the bottom of the hole to the
degree that you have to pick them out, then they aren't likely to come
out all that much better using a horizontal mill, it's the cut threads
that tend to hang on to the chips. Otherwise you could simply blow
them out like drill chips and you wouldn't need to ever pick them out.
Magnets never worked well for me in this instance (even with steel
chips), and I've got a couple of small strong ones. But I don't have
any brass, aluminum, or plastic magnets.
Different style tap? Yep, that's why I suggested form taps.
GarlicDude mentioned spiral flute taps which pull the chips out. I use
them all the time, but the deeper gullets needed for chip flow make
them weaker than normal taps and they therefore have a greater
frequency of snapping off in the hole in tougher materials than do
regular spiral point taps or form taps.

[Garlicdude]

Post by BottleBob
Different style tap? Yep, that's why I suggested form taps.
GarlicDude mentioned spiral flute taps which pull the chips out. I use
them all the time, but the deeper gullets needed for chip flow make them
weaker than normal taps and they therefore have a greater frequency of
snapping off in the hole in tougher materials than do regular spiral
point taps or form taps.

Thread milling works really well for blind holes where your trying for max
thread depth.

[BottleBob]

Post by Garlicdude

Post by BottleBob
Different style tap? Yep, that's why I suggested form taps.
GarlicDude mentioned spiral flute taps which pull the chips out. I
use them all the time, but the deeper gullets needed for chip flow
make them weaker than normal taps and they therefore have a greater
frequency of snapping off in the hole in tougher materials than do
regular spiral point taps or form taps.

Thread milling works really well for blind holes where your trying for
max thread depth.

GD:

You're absolutely correct, and I occasionally use them in critical
operations. BUT........

http://www1.mscdirect.com/CGI/GSDRVSM?PACACHE=000000079403425

1/4-20 Thread mill $200

http://www1.mscdirect.com/CGI/GSDRVSM?PACACHE=000000079403463

1/4-20 Form tap $13.62

[b***@aol.com]

Post by BottleBob

Post by Garlicdude

Post by BottleBob
Different style tap? Yep, that's why I suggested form taps.
GarlicDude mentioned spiral flute taps which pull the chips out. I
use them all the time, but the deeper gullets needed for chip flow
make them weaker than normal taps and they therefore have a greater
frequency of snapping off in the hole in tougher materials than do
regular spiral point taps or form taps.

Thread milling works really well for blind holes where your trying for
max thread depth.

You're absolutely correct, and I occasionally use them in critical
operations. BUT........
http://www1.mscdirect.com/CGI/GSDRVSM?PACACHE=000000079403425
1/4-20 Thread mill $200

http://tinyurl.com/72ye35

Single Profile Thread Mill $54.00

Not for production but for prototype (fixtures, tooling, very short
runs) this type single point thread mill is nice to have. Just like a
single point threading tool on a lathe, a couple sizes will cover a
fairly large range of threads.

http://tinyurl.com/99ckew

Tom

[Garlicdude]

Post by BottleBob

Post by Garlicdude

Post by BottleBob
Different style tap? Yep, that's why I suggested form taps.
GarlicDude mentioned spiral flute taps which pull the chips out. I
use them all the time, but the deeper gullets needed for chip flow
make them weaker than normal taps and they therefore have a greater
frequency of snapping off in the hole in tougher materials than do
regular spiral point taps or form taps.

Thread milling works really well for blind holes where your trying for
max thread depth.

You're absolutely correct, and I occasionally use them in critical
operations. BUT........
http://www1.mscdirect.com/CGI/GSDRVSM?PACACHE=000000079403425
1/4-20 Thread mill $200
http://www1.mscdirect.com/CGI/GSDRVSM?PACACHE=000000079403463
1/4-20 Form tap $13.62

Bob, Your buying thread mills from the wrong place:

http://store.atlascuttingtools.com/servlet/Categories?category=Threadmills+-+Carbide%3AInternal+UN+Threads+-+ALTiN


1/4-20 $65.22 Still not as cheap as a tap, but much more reasonable than MSC

Best,
Steve

[John R. Carroll]

Post by Garlicdude

Post by BottleBob

Post by Garlicdude

Post by BottleBob
Different style tap? Yep, that's why I suggested form taps.
GarlicDude mentioned spiral flute taps which pull the chips out. I use
them all the time, but the deeper gullets needed for chip flow make
them weaker than normal taps and they therefore have a greater
frequency of snapping off in the hole in tougher materials than do
regular spiral point taps or form taps.

Thread milling works really well for blind holes where your trying for
max thread depth.

You're absolutely correct, and I occasionally use them in critical
operations. BUT........
http://www1.mscdirect.com/CGI/GSDRVSM?PACACHE=000000079403425
1/4-20 Thread mill $200
http://www1.mscdirect.com/CGI/GSDRVSM?PACACHE=000000079403463
1/4-20 Form tap $13.62

http://store.atlascuttingtools.com/servlet/Categories?category=Threadmills+-+Carbide%3AInternal+UN+Threads+-+ALTiN
1/4-20 $65.22 Still not as cheap as a tap, but much more reasonable than MSC

About half the cut length though Steve and it looked like they are either
ID/OD, not both. The shanks are also smaller then the intended major
diameter.The extra strength wouldn't matter in Aluminum but it's worth a lot
in 304 or 316 and Super Alloys. I just bought and used 28 pitch
Internal/Externals, coated from OSG. They were $116.00 each but the tools
were gound from 5/16 blanks and had an inch of usable length.
$65.22 is a good price but you'd just be tossing them. The longer cut
lengths can be cheaply reconditioned several times.
I'm not sure how cheaply because I've yet to wear one out <G>

JC

[Garlicdude]

Post by John R. Carroll

Post by Garlicdude

Post by BottleBob

Post by Garlicdude

Post by BottleBob
Different style tap? Yep, that's why I suggested form taps.
GarlicDude mentioned spiral flute taps which pull the chips out. I use
them all the time, but the deeper gullets needed for chip flow make
them weaker than normal taps and they therefore have a greater
frequency of snapping off in the hole in tougher materials than do
regular spiral point taps or form taps.

Thread milling works really well for blind holes where your trying for
max thread depth.

You're absolutely correct, and I occasionally use them in critical
operations. BUT........
http://www1.mscdirect.com/CGI/GSDRVSM?PACACHE=000000079403425
1/4-20 Thread mill $200
http://www1.mscdirect.com/CGI/GSDRVSM?PACACHE=000000079403463
1/4-20 Form tap $13.62

http://store.atlascuttingtools.com/servlet/Categories?category=Threadmills+-+Carbide%3AInternal+UN+Threads+-+ALTiN
1/4-20 $65.22 Still not as cheap as a tap, but much more reasonable than MSC

About half the cut length though Steve and it looked like they are either
ID/OD, not both. The shanks are also smaller then the intended major
diameter.The extra strength wouldn't matter in Aluminum but it's worth a lot
in 304 or 316 and Super Alloys. I just bought and used 28 pitch
Internal/Externals, coated from OSG. They were $116.00 each but the tools
were gound from 5/16 blanks and had an inch of usable length.
$65.22 is a good price but you'd just be tossing them. The longer cut
lengths can be cheaply reconditioned several times.
I'm not sure how cheaply because I've yet to wear one out <G>
JC

John, The above are all valid points. I guess my point is I find MSC to be
wildly overpriced on many items.

Best,
Steve

[BottleBob]

Post by Garlicdude

Post by BottleBob

Post by Garlicdude
Thread milling works really well for blind holes where your trying
for max thread depth.

You're absolutely correct, and I occasionally use them in critical
operations. BUT........
http://www1.mscdirect.com/CGI/GSDRVSM?PACACHE=000000079403425
1/4-20 Thread mill $200
http://www1.mscdirect.com/CGI/GSDRVSM?PACACHE=000000079403463
1/4-20 Form tap $13.62

http://store.atlascuttingtools.com/servlet/Categories?category=Threadmills+-+Carbide%3AInternal+UN+Threads+-+ALTiN
1/4-20 $65.22 Still not as cheap as a tap, but much more reasonable than MSC

Steve:

Actually, we buy a lot of tools from a distributer in the San Fernando
Vally, since they deliver twice a day. I just used MSC since it was a
quick/easy reference.

But the Atlas cutting tools site is definitely a good double check to
keep the little dealers honest - or leverage for getting them to match
their price. <g>

[Cliff]

Post by BottleBob

Post by Garlicdude

Post by BottleBob
Different style tap? Yep, that's why I suggested form taps.
GarlicDude mentioned spiral flute taps which pull the chips out. I
use them all the time, but the deeper gullets needed for chip flow
make them weaker than normal taps and they therefore have a greater
frequency of snapping off in the hole in tougher materials than do
regular spiral point taps or form taps.

Thread milling works really well for blind holes where your trying for
max thread depth.

You're absolutely correct, and I occasionally use them in critical
operations. BUT........
http://www1.mscdirect.com/CGI/GSDRVSM?PACACHE=000000079403425
1/4-20 Thread mill $200
http://www1.mscdirect.com/CGI/GSDRVSM?PACACHE=000000079403463
1/4-20 Form tap $13.62

Probably needs a specialist to resharpen a thread mill?
Form-relieved nodoubt but .. even so, perhaps cheaper on
a per-hole basis?
---
Cliff

[Cliff]

Post by BottleBob

Post by Cliff

Post by BottleBob
Trapped chips in blind holes is the ONE best reason for switching to a
form tap.

Or a horizontal or a magnet or a different style of tap ...

If the chips from tapping are jamming in the bottom of the hole to the
degree that you have to pick them out,

I guess you don't have much of a problem with a 5 ton workpiece ...
just pick it up & jiggle it upside down ....

Post by BottleBob
then they aren't likely to come
out all that much better using a horizontal mill, it's the cut threads
that tend to hang on to the chips. Otherwise you could simply blow
them out like drill chips and you wouldn't need to ever pick them out.

Flying chips are a danger and deep holes like to stay that way.

[BottleBob]

Post by Cliff

Post by BottleBob

Post by Cliff

Post by BottleBob
Trapped chips in blind holes is the ONE best reason for switching to a
form tap.

Or a horizontal or a magnet or a different style of tap ...

If the chips from tapping are jamming in the bottom of the hole to the
degree that you have to pick them out,

I guess you don't have much of a problem with a 5 ton workpiece ...
just pick it up & jiggle it upside down ....

Cliff:

Get out your knitting needles.

[Cliff]

On Mon, 22 Dec 2008 09:31:23 -0500, "Proctologically Violated©®"

Post by Proctologically Violated©®
I have chosen a drill depth 50% greater than the tap depth.

Much depends on the style of tap & the material.

[BottleBob]

Post by Cliff
On Mon, 22 Dec 2008 09:31:23 -0500, "Proctologically Violated©®"

Post by Proctologically Violated©®
I have chosen a drill depth 50% greater than the tap depth.

Much depends on the style of tap & the material.

Cliff:

So how would the depth of the drilled hole need to be changed using a
normal spiral point tap in aluminum, CRS, or 304 Stainless?

[Cliff]

Post by BottleBob

Post by Cliff
On Mon, 22 Dec 2008 09:31:23 -0500, "Proctologically Violated©®"

Post by Proctologically Violated©®
I have chosen a drill depth 50% greater than the tap depth.

Much depends on the style of tap & the material.

So how would the depth of the drilled hole need to be changed using a
normal spiral point tap in aluminum, CRS, or 304 Stainless?

That's a silly question to ask.
And, AFAIK, most spiral point taps are chip-driver taps, best
suited for thru holes (unless you really just want to drill a bit
deeper).

[BottleBob]

Post by Cliff

Post by BottleBob

Post by Cliff
On Mon, 22 Dec 2008 09:31:23 -0500, "Proctologically Violated©®"

Post by Proctologically Violated©®
I have chosen a drill depth 50% greater than the tap depth.

Much depends on the style of tap & the material.

So how would the depth of the drilled hole need to be changed using a
normal spiral point tap in aluminum, CRS, or 304 Stainless?

Cliff:

You wrote: "Much depends on the style of tap & the material."

I thought from that response that my might have some specific tips on
this subject.

Post by Cliff
That's a silly question to ask.

But from your above response, It seems I was in error. Sorry to have
wasted your time.