I am making a drilling/tapping block and I need to drill very straight
holes for 8 sizes of taps. I will be ok with the 1/4" and up, an maybe
even with the #10 tap. But I am looking for ideas on making the holes
for the #6 and #8 taps really straight. Any ideas? The holes will be
1" deep. I will make my prototype from mild steel, but later, I want to
make some from annealed 4140.
Actually, this tool will be used for both drilling and tapping, to
keep the tap drill straight and then to keep the tap straight. It
worked out quite well to just use the clearance drill of one size to be
the tap drill size of the next one, with a couple of minor adjustments.
So, I can cover both tap drills and clearance drills for 8 sizes (#6,
#8, #10, 1/4, 5/16. 3/8 and 1/2) with only 9 holes.

I would appreciate any ideas on making those small holes straight,
Pete Stanaitis

"Pete & sheri" wrote in message
...
I am making a drilling/tapping block and I need to drill very straight
holes for 8 sizes of taps. I will be ok with the 1/4" and up, an maybe
even with the #10 tap. But I am looking for ideas on making the holes
for the #6 and #8 taps really straight. Any ideas? The holes will be
1" deep. I will make my prototype from mild steel, but later, I want to
make some from annealed 4140.
Actually, this tool will be used for both drilling and tapping, to
keep the tap drill straight and then to keep the tap straight. It
worked out quite well to just use the clearance drill of one size to be
the tap drill size of the next one, with a couple of minor adjustments.
So, I can cover both tap drills and clearance drills for 8 sizes (#6,
#8, #10, 1/4, 5/16. 3/8 and 1/2) with only 9 holes.

I would appreciate any ideas on making those small holes straight,
Pete Stanaitis


I have little to offer in the way of preventing drill drifting aside from
using a new undersized drill bit, followed by boring as far as possible,
then reaming to hopefully align the balance of the hole with the bored hole,
which should be dead straight. It's a tough call on small holes, though.

It's interesting to see your post, for there are those that seem to think
that twist drills automatically drill straight holes. I've had more than a
few people tell me they do, and more or less imply I'm crazy. One boldly
stated that he could drill through a foot of material and have his drill
come out on location. My experiences through the years prove I'm right,
though. Twist drills are very capable of drilling irregular and crooked
holes. You're wise to be concerned.

Harold

UUUH- drill bushings?

Willis Gregory

Jon Elson wrote:

Pete & sheri wrote:

I am making a drilling/tapping block and I need to drill very straight
holes for 8 sizes of taps. I will be ok with the 1/4" and up, an
maybe even with the #10 tap. But I am looking for ideas on making the
holes for the #6 and #8 taps really straight. Any ideas? The holes
will be 1" deep. I will make my prototype from mild steel, but later,
I want to make some from annealed 4140.
Actually, this tool will be used for both drilling and tapping, to
keep the tap drill straight and then to keep the tap straight. It
worked out quite well to just use the clearance drill of one size to
be the tap drill size of the next one, with a couple of minor
adjustments.
So, I can cover both tap drills and clearance drills for 8 sizes
(#6, #8, #10, 1/4, 5/16. 3/8 and 1/2) with only 9 holes.

Well, the obvious question is how straight do you need it? Are we talking
half a degree, an arc minute, an arc second? I would thing for tapping an
already existing hole in a part, that it makes no difference as long as the
tapping block is at least as straight as the drilled hole in the workpiece.
That is probably good to 10 arc minutes or so. If I needed to, I could
probably get it down to a few arc seconds, but most people don't have
the tools to measure angles to anywhere near that resolution.

Jon

Hi Pete

Ha ha The last time I was on here talking about straight holes I started
WW3. Don't want to do that again. (I apologize!)

If you think you can drill great 1/4 inch holes then why not drill 1/4 inch
pilot holes. Then turn sleeves a little larger then a press fit in the 1/4
pilot holes. Then chuck up the sleeves and drill them to the size you want.
Then mount the drilled pilot sleeves on dead centers and turn them down to a
proper press fit for the 1/4 inch pilot holes. When done, press the sleeves
into the 1/4 inch pilot holes.

That should work and also give you lots of room to screw the odd one up and
if need be give you the means of changing out any that have become worn.

A lot of work for a few holes.

Bill D

Pete & sheri wrote:

I am making a drilling/tapping block and I need to drill very straight
holes for 8 sizes of taps. I will be ok with the 1/4" and up, an maybe
even with the #10 tap. But I am looking for ideas on making the holes
for the #6 and #8 taps really straight. Any ideas? The holes will be
1" deep. I will make my prototype from mild steel, but later, I want to
make some from annealed 4140.
Actually, this tool will be used for both drilling and tapping, to
keep the tap drill straight and then to keep the tap straight. It
worked out quite well to just use the clearance drill of one size to be
the tap drill size of the next one, with a couple of minor adjustments.
So, I can cover both tap drills and clearance drills for 8 sizes (#6,
#8, #10, 1/4, 5/16. 3/8 and 1/2) with only 9 holes.

I would appreciate any ideas on making those small holes straight,
Pete Stanaitis

Bill wrote:

Hi Pete

Ha ha The last time I was on here talking about straight holes I started
WW3. Don't want to do that again. (I apologize!)

If you think you can drill great 1/4 inch holes then why not drill 1/4 inch
pilot holes. Then turn sleeves a little larger then a press fit in the 1/4
pilot holes. Then chuck up the sleeves and drill them to the size you want.
Then mount the drilled pilot sleeves on dead centers and turn them down to a
proper press fit for the 1/4 inch pilot holes. When done, press the sleeves
into the 1/4 inch pilot holes.

That should work and also give you lots of room to screw the odd one up and
if need be give you the means of changing out any that have become worn.

A lot of work for a few holes.

Bill D

Pete & sheri wrote:

I am making a drilling/tapping block and I need to drill very straight
holes for 8 sizes of taps. I will be ok with the 1/4" and up, an maybe
even with the #10 tap. But I am looking for ideas on making the holes
for the #6 and #8 taps really straight. Any ideas? The holes will be
1" deep. I will make my prototype from mild steel, but later, I want to
make some from annealed 4140.
Actually, this tool will be used for both drilling and tapping, to
keep the tap drill straight and then to keep the tap straight. It
worked out quite well to just use the clearance drill of one size to be
the tap drill size of the next one, with a couple of minor adjustments.
So, I can cover both tap drills and clearance drills for 8 sizes (#6,
#8, #10, 1/4, 5/16. 3/8 and 1/2) with only 9 holes.

I would appreciate any ideas on making those small holes straight,
Pete Stanaitis

I'm wondering why such a long hole for the smaller taps. Really seems overkill,
and rather restrictive.

mj

It depends on how straight you want it. I recently drilled a pilot
hole thru a block of annealed 4340 just over 2 1/2 inches thick.
Other than using a drill press and getting the drill exactly over the
center punch dent, I didn't do any thing special. I think it was
straight enough for what you want to do.

Dan


Pete & sheri wrote in message

But I am looking for ideas on making the holes
for the #6 and #8 taps really straight. Any ideas? The holes will be
1" deep. I will make my prototype from mild steel, but later, I want to
make some from annealed 4140.

I would appreciate any ideas on making those small holes straight,
Pete Stanaitis

Hi, Pete, Bill has a great suggestion here but it is rather time consuming
and might be more accurate than you need.

My suggestion would be you use a newly sharpened drill, then peck at it,
maybe .050" at a time and rotate the part 90 degrees every time.

--
Lewis.

..........................

*******************************

"Bill" wrote in message
...
Hi Pete

Ha ha The last time I was on here talking about straight holes I started
WW3. Don't want to do that again. (I apologize!)

If you think you can drill great 1/4 inch holes then why not drill 1/4
inch
pilot holes. Then turn sleeves a little larger then a press fit in the
1/4
pilot holes. Then chuck up the sleeves and drill them to the size you
want.
Then mount the drilled pilot sleeves on dead centers and turn them down to
a
proper press fit for the 1/4 inch pilot holes. When done, press the
sleeves
into the 1/4 inch pilot holes.

That should work and also give you lots of room to screw the odd one up
and
if need be give you the means of changing out any that have become worn.

A lot of work for a few holes.

Bill D

Pete & sheri wrote:

I am making a drilling/tapping block and I need to drill very straight
holes for 8 sizes of taps. I will be ok with the 1/4" and up, an maybe
even with the #10 tap. But I am looking for ideas on making the holes
for the #6 and #8 taps really straight. Any ideas? The holes will be
1" deep. I will make my prototype from mild steel, but later, I want to
make some from annealed 4140.
Actually, this tool will be used for both drilling and tapping, to
keep the tap drill straight and then to keep the tap straight. It
worked out quite well to just use the clearance drill of one size to be
the tap drill size of the next one, with a couple of minor adjustments.
So, I can cover both tap drills and clearance drills for 8 sizes (#6,

#8, #10, 1/4, 5/16. 3/8 and 1/2) with only 9 holes.

I would appreciate any ideas on making those small holes straight,
Pete Stanaitis

Pete & sheri wrote:

I am making a drilling/tapping block and I need to drill very straight
holes for 8 sizes of taps. I will be ok with the 1/4" and up, an
maybe even with the #10 tap. But I am looking for ideas on making the
holes for the #6 and #8 taps really straight. Any ideas? The holes
will be 1" deep. I will make my prototype from mild steel, but later,
I want to make some from annealed 4140.
Actually, this tool will be used for both drilling and tapping, to
keep the tap drill straight and then to keep the tap straight. It
worked out quite well to just use the clearance drill of one size to
be the tap drill size of the next one, with a couple of minor
adjustments.
So, I can cover both tap drills and clearance drills for 8 sizes
(#6, #8, #10, 1/4, 5/16. 3/8 and 1/2) with only 9 holes.

Well, the obvious question is how straight do you need it? Are we talking
half a degree, an arc minute, an arc second? I would thing for tapping an
already existing hole in a part, that it makes no difference as long as the
tapping block is at least as straight as the drilled hole in the workpiece.
That is probably good to 10 arc minutes or so. If I needed to, I could
probably get it down to a few arc seconds, but most people don't have
the tools to measure angles to anywhere near that resolution.

Jon

Pete & sheri wrote in message ...
I am making a drilling/tapping block and I need to drill very straight
holes for 8 sizes of taps. I will be ok with the 1/4" and up, an maybe
even with the #10 tap. But I am looking for ideas on making the holes
for the #6 and #8 taps really straight. Any ideas? The holes will be
1" deep. I will make my prototype from mild steel, but later, I want to
make some from annealed 4140.
Actually, this tool will be used for both drilling and tapping, to
keep the tap drill straight and then to keep the tap straight. It
worked out quite well to just use the clearance drill of one size to be
the tap drill size of the next one, with a couple of minor adjustments.
So, I can cover both tap drills and clearance drills for 8 sizes (#6,
#8, #10, 1/4, 5/16. 3/8 and 1/2) with only 9 holes.

I would appreciate any ideas on making those small holes straight,
Pete Stanaitis


Well, I'd go the one poster one better. Go buy some drilling fixture
bushings, they're pretty cheap and readily available, when worn, you
don't have to chuck your block, just get a new bushing. You could
also make your own, drill your hole in an oversized piece of stock,
chuck between centers, turn outside to a slip fit in your block hole.
If you were really serious about it, you'd drill undersize, rough turn
the outside, harden and temper, chuck between centers, grind the
outside, chuck in a 4-jaw and grind the inside to size. Much easier
to buy the things, unless you're dead and your time isn't worth
anything.
Brownells sells a pretty nifty tapping block with removable bushings,
I've got one from way back, they're asking a lot more money these
days, though. Works great for round or flat work.


Stan

In article , Harold & Susan Vordos says...

Twist drills are very capable of drilling irregular and crooked
holes. You're wise to be concerned.

I agree. There is no way he can produce
the hole he wants, to the tolerance level
he requires, using a twist drill. It's
simply impossible to make the hole straight
to within the required 5 microinches that
he needs.

He should probably just buy the tapping
block instead.



Jim

==================================================
please reply to:
JRR(zero) at yktvmv (dot) vnet (dot) ibm (dot) com
==================================================

Bill wrote:
Hi Pete

Ha ha The last time I was on here talking about straight holes I
started WW3. Don't want to do that again. (I apologize!)

OK. Define straight! (BG)
Ken.

Ken Davey wrote:

Bill wrote:
Hi Pete

Ha ha The last time I was on here talking about straight holes I
started WW3. Don't want to do that again. (I apologize!)

OK. Define straight! (BG)
Ken.

Not on a bet Ken!!!! (0: GBFG

Hmm, one thing that could help in a big way is the spindle being trammed
to the work surface. Having the collet/chuck/tool running true can
affect the outcome. Sometimes the trees obscure the view. ;)

mj

Lewis Campbell wrote:


My suggestion would be you use a newly sharpened drill, then peck at it,
maybe .050" at a time and rotate the part 90 degrees every time.


In addition, hold workpiece in a vise mounted solidly to the mill or
drill table. Use a center or spotting drill first. Drill next with a
stubby, stiff drill. You may need to shorten one by cutting off the
shank end. It should hang out of the chuck a minimal amount to avoid
deflection. Extend the drill "length" as you reach it's depth limit. At
some point you can use a regular length drill bit. Between pecks, blow
away the chips and get coolant to the bottom of the hole.
--
Randy Replogle (Central Indiana)

Pete & sheri wrote:

I am making a drilling/tapping block and I need to drill very straight
holes for 8 sizes of taps.

I have some drill/tap guides I picked up at Boeing Surplus. You might
copy the design. These are a clear plastic device with three legs and a
flat surface with a threaded metal insert. The guides screw into this
device. Using these, you make a guide for each desired size. Rough the
insert or use a short bolt. Drill the guide hole, mount between centers
and face the seating surface.

Not much of a description but I could send or post a picture.

Ted

On Mon, 29 Dec 2003 13:17:15 -0600, Pete & sheri
wrote:

I am making a drilling/tapping block and I need to drill very straight
holes for 8 sizes of taps. I will be ok with the 1/4" and up, an maybe
even with the #10 tap. But I am looking for ideas on making the holes
for the #6 and #8 taps really straight. Any ideas? The holes will be
1" deep. I will make my prototype from mild steel, but later, I want to
make some from annealed 4140.
Actually, this tool will be used for both drilling and tapping, to
keep the tap drill straight and then to keep the tap straight. It
worked out quite well to just use the clearance drill of one size to be
the tap drill size of the next one, with a couple of minor adjustments.
So, I can cover both tap drills and clearance drills for 8 sizes (#6,
#8, #10, 1/4, 5/16. 3/8 and 1/2) with only 9 holes.

I would appreciate any ideas on making those small holes straight,
Pete Stanaitis


Some thoughts

The axis of the drill/workpiece rotation must be concentric with the
first point at which the drill starts to cut. A twist drill has litle
sideways stiffness so it initially starts a hole concentric with this
initial cut point and then tries to drift to cutting concentric with
the rotation axis.

Standard jobber drills working without an initial centre punch
dot are pretty poor and may start to cut at almost any point along the
edge of the chisel tip. A centre punch dot provides a strong initial
centering force but, unless the dot is truly symmetrical and precisely
aligned with the rotation axis there will still be a residual starting
error.

For centre punch dot starting a good strategy is to chuck a short
piece of hardened drill rod with a 90deg conical point and press this,
slowly rotating, into the workpiece to form a depression at least as
wide as the drill chisel tip. This gives a well centered symmetrical
start but may not be easy with a pretty hard workpiece. A split point
drill is helpful because of its short effective chisel point length.

An alternative is to start the hole with a very short stiff drill
with the smallest practicable chisel point. NC spotting drills are
ideal for this method. The spotting drill can be much larger (and
stiffer) than the final hole size because it is only used to provide a
start for the final hole.

If it's possible to chuck the workpiece in a lathe rather than
using a drill press, the start of the hole can be single point bored
to near full diameter and this will guarantee concentricity with the
rotation axis.

With twist drills, once entered the workpiece, the straightness
is mainly determined by the symmetry of the cutting edges and the
uniformity of the feed force. The main effect of slighly assymetric
cutting edges is to generate a sideways force. This will cause the
drill to cut a little oversize but, if the feed force is constant and
the workpiece material is uniform, the sideways force will also be
uniform so the hole will still be straight. In practice both are a bit
variable and the variabilty initiates sideways force variations.
These start asymmetries and the drill will tend to follow the
direction of any initially small induced asymmetry.

To minimise this problem every effort needs to be made to
minimise the unwanted sideways forces. Things that come to mind:-

Well formed and symmetrical drill point
Sharp cutting edges
Split point drill
Easily machinable workpiece material
Light and uniform infeed - preferably by power feed

Let us know how you get on and whether any of the hints
actually worked!

Jim

Thanks to all of you for your input.

I will use brand new drill bits, possibly with a pilot point. I will
locate the holes using coordinates and start each hole with a center
drill, allowing it to hover in the hole so it centers well.
Your comments about steady feed and pecking will help.

I don't think I will go to drill bushings, though. Just too much effort.
I would like to eventually make several of these tools.

Thanks again,
Pete Stanaitis

Pete & sheri wrote:

Thanks to all of you for your input.

I will use brand new drill bits, possibly with a pilot point. I will
locate the holes using coordinates and start each hole with a center
drill, allowing it to hover in the hole so it centers well.
Your comments about steady feed and pecking will help.

I don't think I will go to drill bushings, though. Just too much effort.
I would like to eventually make several of these tools.

Thanks again,
Pete Stanaitis

Hover in the hole? Contact the work, lean on it a bit, retract. "Hovering",
which I presume to mean the intention of dwelling, will workharden your
block and dull your c/drill.

mj

A city wide blackout at Mon, 29 Dec 2003 12:37:44 -0800 did not prevent
"Harold & Susan Vordos" from posting to
rec.crafts.metalworking the following:


I have little to offer in the way of preventing drill drifting aside from
using a new undersized drill bit, followed by boring as far as possible,
then reaming to hopefully align the balance of the hole with the bored hole,
which should be dead straight. It's a tough call on small holes, though.

It's interesting to see your post, for there are those that seem to think
that twist drills automatically drill straight holes. I've had more than a
few people tell me they do, and more or less imply I'm crazy. One boldly
stated that he could drill through a foot of material and have his drill
come out on location. My experiences through the years prove I'm right,
though. Twist drills are very capable of drilling irregular and crooked
holes. You're wise to be concerned.

Even boring tools can drift. Maybe not as much as a drill would, but .600
is a lot of run out. Okay, so its a hole 31 1/2 feet long. ... nothing is
perfectly straight without work.

--
pyotr filipivich.
as an explaination for the decline in the US's tech edge, James
Niccol wrote "It used to be that the USA was pretty good at
producing stuff teenaged boys could lose a finger or two playing with."

On Wed, 31 Dec 2003 16:47:12 GMT, pyotr filipivich
wrote:

A city wide blackout at Mon, 29 Dec 2003 12:37:44 -0800 did not prevent
"Harold & Susan Vordos" from posting to
rec.crafts.metalworking the following:


I have little to offer in the way of preventing drill drifting aside from
using a new undersized drill bit, followed by boring as far as possible,
then reaming to hopefully align the balance of the hole with the bored hole,
which should be dead straight. It's a tough call on small holes, though.

It's interesting to see your post, for there are those that seem to think
that twist drills automatically drill straight holes. I've had more than a
few people tell me they do, and more or less imply I'm crazy. One boldly
stated that he could drill through a foot of material and have his drill
come out on location. My experiences through the years prove I'm right,
though. Twist drills are very capable of drilling irregular and crooked
holes. You're wise to be concerned.

Even boring tools can drift. Maybe not as much as a drill would, but .600
is a lot of run out. Okay, so its a hole 31 1/2 feet long. ... nothing is
perfectly straight without work.

Ive got a very nice Eldorado Gun Drill for sale, if anyone wants really
deep straight holes...

Gunner



"Aren't cats Libertarian? They just want to be left alone.
I think our dog is a Democrat, as he is always looking for a handout"
Unknown Usnet Poster

Heh, heh, I'm pretty sure my dog is a liberal - he has no balls.
Keyton

"Gunner" wrote in message
...
On Wed, 31 Dec 2003 16:47:12 GMT, pyotr filipivich
wrote:

snip----

Even boring tools can drift. Maybe not as much as a drill would, but
..600
is a lot of run out. Okay, so its a hole 31 1/2 feet long. ... nothing
is
perfectly straight without work.

Ive got a very nice Eldorado Gun Drill for sale, if anyone wants really
deep straight holes...

Gunner

Certainly far better than drilling with twist drills, but I recall watching
P.O. Ackley straightening barrels drilled that way too. :-)

Harold

I use a steady feed and try to drill so that the chips come out in two
long strings. When you get deeper, the chips will start to break into
pieces and then you need to retract the drill to get the chips out of
the hole. The pecking is more drill until the chips start to jam in
the hole, then retract and clear the chips. So with a .138 drill you
might get a half inch before the chips start breaking up. After that
you will probably only get about 1/4 inch more drilled until you have
to retract and clear the chips.

Jim Pentagrid wrote an excellent bit on the problems and solutions.

Dan


Pete & sheri wrote in message


Your comments about steady feed and pecking will help.


Thanks again,
Pete Stanaitis

On Wed, 31 Dec 2003 13:22:02 -0800, "Harold & Susan Vordos"
wrote:


"Gunner" wrote in message
.. .
On Wed, 31 Dec 2003 16:47:12 GMT, pyotr filipivich
wrote:

snip----

Even boring tools can drift. Maybe not as much as a drill would, but
.600
is a lot of run out. Okay, so its a hole 31 1/2 feet long. ... nothing
is
perfectly straight without work.

Ive got a very nice Eldorado Gun Drill for sale, if anyone wants really
deep straight holes...

Gunner

Certainly far better than drilling with twist drills, but I recall watching
P.O. Ackley straightening barrels drilled that way too. :-)

Harold


St. Ackley never used an Eldorado gun drill G

Drill, THEN turn to profile between centers G

Gunner

"Gun Control, the theory that a 110lb grandmother should
fist fight a 250lb 19yr old criminal"

"Gunner" wrote in message
...
On Wed, 31 Dec 2003 13:22:02 -0800, "Harold & Susan Vordos"
wrote:


"Gunner" wrote in message
.. .
On Wed, 31 Dec 2003 16:47:12 GMT, pyotr filipivich
wrote:

snip----

Even boring tools can drift. Maybe not as much as a drill would, but
.600
is a lot of run out. Okay, so its a hole 31 1/2 feet long. ...
nothing
is
perfectly straight without work.

Ive got a very nice Eldorado Gun Drill for sale, if anyone wants really
deep straight holes...

Gunner

Certainly far better than drilling with twist drills, but I recall
watching
P.O. Ackley straightening barrels drilled that way too. :-)

Harold


St. Ackley never used an Eldorado gun drill G

Drill, THEN turn to profile between centers G

Gunner


You're most likely right. I think my point was that even gun drilled holes
aren't necessarily dead straight (what does that really mean?), but then
after turning the OD , you'd certainly have error to remove, even if the
barrel had been drilled what could be considered straight. My report of
watching him straighten barrels is the only part I recall, that and the fact
that it was all done with an overhead press and checked by sight. It's
been about 20 years. Hell, he died in '89. Time flies!

Harold