Looking for any tips/tricks for drilling a hole w/a drill press that's as
close to dead-center to a specified point as possible.
Here's what I've been doing - I have the position marked with graph paper
that's taped to the workpiece. With the help of a magnifying glass, I
painstakingly move the piece until the tip of the bit is aligned with the
conjoining lines. By aligning with the tip I mean I view the tip both from
the narrow or "pointy" persepective within the channel of the bit and then
turn it 90 deg and look at the the wider perspective, and view it from the
side and front to make sure I have it aligned with both the X and Y axis.
When I finally get it so the tip is as centered as I can make it whichever
way the bit is turned and in relation to both axis, I clamp the piece to the
plate of the drill press and drill the hole. However, on examination, the
hole comes out obviously not dead center in relation to the graph paper
lines.
I've also tried aliging it with the drill running, going visually by where
the "point" appears to be when the bit is spinning. I get somewhat better
results this way but wonder if there's a more precise and dependable way of
achieving a centered hole.
Thanks for any input.
> I've also tried aliging it with the drill running, going visually by where
> the "point" appears to be when the bit is spinning. I get somewhat better
> results this way but wonder if there's a more precise and dependable way
> of
> achieving a centered hole.
Have you tried using brad point or forstner bits? You could also chuck a
centering bit to line up and clamp your workpiece.
First of all, forget "absolutely dead center" -- that term is incompatible
with a drill press. A drill press is a tool for rapidly putting holes within
a reasonable tolerance of where you want them. That being said, this problem
breaks down as:
1) making the hole start directly under the spindle axis (i.e. preventing drill
bit wander) which is done by centerpunching and also by using very rigid drill
bits known as "center drills" which you can get at http://www.mscindustrial.com
2) putting your centerpunch mark exactly where you want it which is easy to
do within ten thousandths but very hard to do closer than two thousandths. This
is done for high precision by the use of an optical center punch.
Holes that have to be very precisely located aren't drilled, they are bored.
The machine that does this is a jig borer.
Most woodworking tolerances are on the order of .010" so you can probably
get away with learning to do layout and centerpunching. Once you have a
centerpunched mark, then it's also tricky to get it lined up exactly under
the machine's axis.
All of this supposes that your drill press table is at precisely right angle
to the spindle axis, and that your drill chuck has zero runout, neither of
which is likely true, especially if you're using something you bought at
Home Depot.
GWE
Doc wrote:
> Looking for any tips/tricks for drilling a hole w/a drill press that's as
> close to dead-center to a specified point as possible.
>
> Here's what I've been doing - I have the position marked with graph paper
> that's taped to the workpiece. With the help of a magnifying glass, I
> painstakingly move the piece until the tip of the bit is aligned with the
> conjoining lines. By aligning with the tip I mean I view the tip both from
> the narrow or "pointy" persepective within the channel of the bit and then
> turn it 90 deg and look at the the wider perspective, and view it from the
> side and front to make sure I have it aligned with both the X and Y axis.
> When I finally get it so the tip is as centered as I can make it whichever
> way the bit is turned and in relation to both axis, I clamp the piece to the
> plate of the drill press and drill the hole. However, on examination, the
> hole comes out obviously not dead center in relation to the graph paper
> lines.
>
> I've also tried aliging it with the drill running, going visually by where
> the "point" appears to be when the bit is spinning. I get somewhat better
> results this way but wonder if there's a more precise and dependable way of
> achieving a centered hole.
>
> Thanks for any input.
>
>
A great tool for dead-centering is available from Micro-Mark. It is
a laser guide which is gripped in the chuck and projects a red dot
onto the workpiece:
http://www.ares-server.com/Ares/Ares.asp?MerchantID=RET01229&Action=Catalog&Type=Product&ID=83191
Of course, you will still need to centerpunch and/or use a center
drill as outlined in the other responses. The laser guide just
assures that the drill is aimed EXACTLY where it should be!
--
H. L. Law
Doc wrote:
> Looking for any tips/tricks for drilling a hole w/a drill press
that's as
> close to dead-center to a specified point as possible.
>
> Here's what I've been doing - I have the position marked with graph
paper
> that's taped to the workpiece. With the help of a magnifying glass, I
> painstakingly move the piece until the tip of the bit is aligned with
the
> conjoining lines. By aligning with the tip I mean I view the tip both
from
> the narrow or "pointy" persepective within the channel of the bit and
then
> turn it 90 deg and look at the the wider perspective, and view it
from the
> side and front to make sure I have it aligned with both the X and Y
axis.
> When I finally get it so the tip is as centered as I can make it
whichever
> way the bit is turned and in relation to both axis, I clamp the piece
to the
> plate of the drill press and drill the hole. However, on examination,
the
> hole comes out obviously not dead center in relation to the graph
paper
> lines.
>
> I've also tried aliging it with the drill running, going visually by
where
> the "point" appears to be when the bit is spinning. I get somewhat
better
> results this way but wonder if there's a more precise and dependable
way of
> achieving a centered hole.
>
> Thanks for any input.
Without a spotting pip, you'll never, never get your hole dead center
that way. A drill press will be too loose for it and the drill will
always skate. Some of the guys will recommend using a spotting drill
to start with. You can get within a couple of thousandths using one of
the optical center punches where you line up the mark in the crosshairs
and then substitute the marking punch. That would probably be the best
method for what you've described, if it's a one-off. Using stub drills
will help, too. Get name brands, cheapy chink ones will do you
absolutely no good at all.
There's other methods, but if all you've got on hand is a drill press,
suggesting use of a vertical mill is kind of useless. Guy Lautard
details a poor-man's jig borer for drill press use in one of his later
Bedside Reader series but you aren't going to make that up with just a
drill press on hand, either.
Stan
Get a center finder- used to use them in machining all the time--
simply a 1/4" rod with a 30 degree cone machined on one end. Helps to
center punch the center of the hole on the workpiece first, as the
indentation will provide an easy physical reference for the end of the
finder.
Chuck it in the drill press
Find the center of your drill hole- you may want to lock the quill at
this point
Clamp the work to the table-- unlock the quill
Change out the center finder with the bit you will use
Drill
"Dave Baker" <[email protected]> wrote in message
news:[email protected]...
> Turn a sharp point on a bit of thin bar in the lathe and use that in your
> drill chuck to centre on your graph paper. Ideally make it with a collet
> chuck or 4 jaw chuck to get it dead concentric. Then use a centre drill to
> start the hole before drilling right through.
>
> Your pointy bar will also come in handy for setting tool heights exactly
on
> centre on the lathe. I have a couple of them in various sizes made out of
> old engine valve stems and bits of ground silver steel.
>
>
Easy to make these. Next time you are in a machine shop supply get some
metal dowel pins. (They are cheap, a good hardware store might have them
also.) Chuck them up in your hand drill and spin them when you grind the
point, being sure to have a little cup of water to cool the point as you are
grinding.
The op didn't say what material he was trying to drill but in some instances
you can get close to the center punched point and let the work float into
position under the spinning drill bit. If he is drilling wood, a brad point
is in order.
Another way would be to position a piece of Plexiglas that has a guide
bushing centered on a set of cross hairs. Then you can extend the reference
lines on the graph paper and the center will then be right over the target.
--
Roger Shoaf
About the time I had mastered getting the toothpaste back in the tube, then
they come up with this striped stuff.
If you get better results when the drill press is running I think you
have excessive runout in the quill.
Put a long bit ,largest diameter the chuck will take, turn drill press
on. Do you see any wobble?
If you have a dial indicator and a length of drill rod, you can check
runout better.Sometimes the chuck can be at fault, though probably not.
mike
On Thu, 06 Jan 2005 22:43:09 GMT, "Doc" <[email protected]>
wrote:
>Looking for any tips/tricks for drilling a hole w/a drill press that's as
>close to dead-center to a specified point as possible.
>
>Here's what I've been doing - I have the position marked with graph paper
>that's taped to the workpiece. With the help of a magnifying glass, I
>painstakingly move the piece until the tip of the bit is aligned with the
>conjoining lines. By aligning with the tip I mean I view the tip both from
>the narrow or "pointy" persepective within the channel of the bit and then
>turn it 90 deg and look at the the wider perspective, and view it from the
>side and front to make sure I have it aligned with both the X and Y axis.
>When I finally get it so the tip is as centered as I can make it whichever
>way the bit is turned and in relation to both axis, I clamp the piece to the
>plate of the drill press and drill the hole. However, on examination, the
>hole comes out obviously not dead center in relation to the graph paper
>lines.
>
>I've also tried aliging it with the drill running, going visually by where
>the "point" appears to be when the bit is spinning. I get somewhat better
>results this way but wonder if there's a more precise and dependable way of
>achieving a centered hole.
>
>Thanks for any input.
Have you tried making a little hole where you want to drill with a
scratch awl first? You could set the bit right into the divot while
the press is off, then clamp the piece in place and go to town.
Aut inveniam viam aut faciam
Doc wrote:
> Looking for any tips/tricks for drilling a hole w/a drill press that's as
> close to dead-center to a specified point as possible.
First tip: use an awl or center punch (depending on whether it's wood or
metal you're drilling) to mark the precise location of the hole first.
Even with a brad point bit, it's difficult to prevent drills from wandering
off the target when they enter the material. The smaller the gauge of the
bit, the worse the problem is.
Second tip: depending on the nature of the work involved, you may be able
to use a cross-slide vise for fine positioning of the work relative to the
bit. They only work on stock that can fit inside the jaws, but they are
quite useful to have when precision matters.
Something like this:
http://www.grizzly.com/products/item.cfm?itemnumber=G1064
Now, whether you have one of those handy gizmos or not, position the work
(with the hole locations pre-punched), then pull down the quill with the
motor off. Listen for a plinking sound, and watch with hawk eyes for the
slightest bit deflection. If the bit is deflecting to enter the dimple,
your hole won't come out right.
I find it helpful to rotate the chuck by hand to position the flutes or
other cutting edges in a way that allows a clear view of the very tip of
the point in relation to the dimple. Repeat the process of making fine
adjustments to the X and Y axes and then checking with the quill until the
bit enters straight and true, then drill the hole.
This process is tedious and time consuming, but if there's a better way to
ensure a hole as close to perfectly placed as possible with a drill press,
I haven't discovered it.
--
Michael McIntyre ---- Silvan <[email protected]>
Linux fanatic, and certified Geek; registered Linux user #243621
http://www.geocities.com/Paris/Rue/5407/
http://rosegarden.sourceforge.net/tutorial/
--
--
Dave Baker - Puma Race Engines (www.pumaracing.co.uk)
Doc <[email protected]> wrote in message
news:1ajDd.2352$%[email protected]...
> Looking for any tips/tricks for drilling a hole w/a drill press that's as
> close to dead-center to a specified point as possible.
>
> Here's what I've been doing - I have the position marked with graph paper
> that's taped to the workpiece. With the help of a magnifying glass, I
> painstakingly move the piece until the tip of the bit is aligned with the
> conjoining lines. By aligning with the tip I mean I view the tip both from
> the narrow or "pointy" persepective within the channel of the bit and then
> turn it 90 deg and look at the the wider perspective, and view it from the
> side and front to make sure I have it aligned with both the X and Y axis.
> When I finally get it so the tip is as centered as I can make it whichever
> way the bit is turned and in relation to both axis, I clamp the piece to
the
> plate of the drill press and drill the hole. However, on examination, the
> hole comes out obviously not dead center in relation to the graph paper
> lines.
>
> I've also tried aliging it with the drill running, going visually by where
> the "point" appears to be when the bit is spinning. I get somewhat better
> results this way but wonder if there's a more precise and dependable way
of
> achieving a centered hole.
>
> Thanks for any input.
Turn a sharp point on a bit of thin bar in the lathe and use that in your
drill chuck to centre on your graph paper. Ideally make it with a collet
chuck or 4 jaw chuck to get it dead concentric. Then use a centre drill to
start the hole before drilling right through.
Your pointy bar will also come in handy for setting tool heights exactly on
centre on the lathe. I have a couple of them in various sizes made out of
old engine valve stems and bits of ground silver steel.
if you have a 2 inch diameter piece for instance, set a pair of dial
calipers[preferably the 15 dollar chineses ones] a tad over half, say
1.015. scribe a number of lines near the center of the shaft from
different points on the circumference. Of course layout die[read
sharpie] makes it easier to see. You will end up with a pattern grouped
around the center, making it much easier to see if you are in error when
you center punch it. I prefer solid punches to the automatic ones,
sharpened to a nice sharp point.
Tap very lightly the first time, so if it is visibly out of center, you
can fix it.
drill with a small center drill or a 1/8 inch drill. drill progressively
larger
Much of this relates to your eye; if you can see[and care about] the
error or not. If your scribe marks are ~.03 apart, the average person
can 'see' ~.005 error, if they want to.
Silvan wrote:
> Doc wrote:
>
>
>>Looking for any tips/tricks for drilling a hole w/a drill press that's as
>>close to dead-center to a specified point as possible.
>
>
> First tip: use an awl or center punch (depending on whether it's wood or
> metal you're drilling) to mark the precise location of the hole first.
> Even with a brad point bit, it's difficult to prevent drills from wandering
> off the target when they enter the material. The smaller the gauge of the
> bit, the worse the problem is.
>
> Second tip: depending on the nature of the work involved, you may be able
> to use a cross-slide vise for fine positioning of the work relative to the
> bit. They only work on stock that can fit inside the jaws, but they are
> quite useful to have when precision matters.
>
> Something like this:
>
> http://www.grizzly.com/products/item.cfm?itemnumber=G1064
>
> Now, whether you have one of those handy gizmos or not, position the work
> (with the hole locations pre-punched), then pull down the quill with the
> motor off. Listen for a plinking sound, and watch with hawk eyes for the
> slightest bit deflection. If the bit is deflecting to enter the dimple,
> your hole won't come out right.
>
> I find it helpful to rotate the chuck by hand to position the flutes or
> other cutting edges in a way that allows a clear view of the very tip of
> the point in relation to the dimple. Repeat the process of making fine
> adjustments to the X and Y axes and then checking with the quill until the
> bit enters straight and true, then drill the hole.
>
> This process is tedious and time consuming, but if there's a better way to
> ensure a hole as close to perfectly placed as possible with a drill press,
> I haven't discovered it.
>
Doc wrote:
>
> Looking for any tips/tricks for drilling a hole w/a drill press that's as
> close to dead-center to a specified point as possible.
>
> Here's what I've been doing - I have the position marked with graph paper
> that's taped to the workpiece. With the help of a magnifying glass, I
> painstakingly move the piece until the tip of the bit is aligned with the
> conjoining lines. By aligning with the tip I mean I view the tip both from
> the narrow or "pointy" persepective within the channel of the bit and then
> turn it 90 deg and look at the the wider perspective, and view it from the
> side and front to make sure I have it aligned with both the X and Y axis.
> When I finally get it so the tip is as centered as I can make it whichever
> way the bit is turned and in relation to both axis, I clamp the piece to the
> plate of the drill press and drill the hole. However, on examination, the
> hole comes out obviously not dead center in relation to the graph paper
> lines.
>
> I've also tried aliging it with the drill running, going visually by where
> the "point" appears to be when the bit is spinning. I get somewhat better
> results this way but wonder if there's a more precise and dependable way of
> achieving a centered hole.
>
> Thanks for any input.
You got to drill a center punched mark with a very small drill. Then
drill the hole larger with the next size or two up. Recheck the
locantion and if it is off, hit the top edge of the hole with a punch on
the side of the hole you want the hole to move to.
You could also drill the hole a 32th under size and then go through it
with the proper size end mill if your drillpress quill is stiff enough,
or drill another block with the finishe size and clamp that block in
place and use that to hold the endmill on center useing it as a guide
bushing.
John
Doc wrote:
> Looking for any tips/tricks for drilling a hole w/a drill press that's as
> close to dead-center to a specified point as possible.
The usual way is to use a centerpunch.
Most of the time I use an automatic centerpunch to start, then deepen it
with a "manual" centerpunch and hammer.
Auto-centerpunches are available at most any hardware outlet, less than
$10 USD.
Ken Grunke
--
take da "ma" offa dot com fer eemayl
----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==----
http://www.newsfeeds.com The #1 Newsgroup Service in the World! >100,000 Newsgroups
---= East/West-Coast Server Farms - Total Privacy via Encryption =---
On Thu, 06 Jan 2005 22:43:09 GMT, "Doc" <[email protected]>
wrote:
>Looking for any tips/tricks for drilling a hole w/a drill press that's as
>close to dead-center to a specified point as possible.
The problem is not so much your alignment, as the fact that unless the
end of the drill is perfectly symetrical and equally sharp on both
cutting edges, it has a tendency to wander off.
You don't say how big the hole is. If it's small, a full length drill
is very hard to control because there's so much flex in the shaft.
Instead use a center drill like these to start the hole:
http://www.sherline.com/3021inst.htm
If the hole is larger than 1/4 inch, use a spotting drill like one of
these: http://www.discount-tools.com/1545.cfm
Short, stocky drills like that don't wander around when their cutting
tips meet the work.
On Fri, 07 Jan 2005 07:25:41 GMT, "Doc" <[email protected]>
wrote:
>
>"Grant Erwin" <[email protected]> wrote in message
>news:[email protected]...
>
>> All of this supposes that your drill press table is at precisely right
>angle
>> to the spindle axis, and that your drill chuck has zero runout, neither of
>> which is likely true, especially if you're using something you bought at
>> Home Depot.
>
>Oh, so next I 'spose you'll say it was foolhardy of me to bid on doing work
>for NASA with a Shopsmith??
>
>;-)
>
damn.. YOU were the one that undercut my Shopsmith bid!
mac
Please remove splinters before emailing
"Doc" <[email protected]> wrote in message
news:[email protected]...
>
> "Doc" <[email protected]> wrote in message
> news:1ajDd.2352$%[email protected]...
> > Looking for any tips/tricks for drilling a hole w/a drill press that's
as
> > close to dead-center to a specified point as possible.
>
> I was surprised at the number of replies I got in such a short time. It
> occurred to me that I never said that I'm drilling into wood.
Let me amend that, plexi that's been glued over wood.
"Doc" <[email protected]> wrote in message
news:1ajDd.2352$%[email protected]...
> Looking for any tips/tricks for drilling a hole w/a drill press that's as
> close to dead-center to a specified point as possible.
>
My ears are burning....
"Absolute" DOES NOT work in machining. There is _always_ a tolerance. Sorry
for being obnoxious but when you start to get paid to do this work,
tolerances are not a factor - they are life.
What is your application? Do you need your hole to be straight as well?
Others have given good advice. Do you have a combination square with a
"center head"? These are specifically used to draw a line on the flat face
of a cylinder which intersects the center of that cylinder (the line is a
"diameter"). Drawing two such lines (three may be better if your stock is
uneven about its diameter) will give you the center of your part.
Simply center punch (you may want to use a prick punch first), center-drill,
pilot drill (if final diameter exceeds roughly 1/4"), drill, then ream if
necessary.
While this will give you the location of the *top* of your hole, anything
below the surface is a crap shoot and is severely dependant upon your
knowledge and skill of setting up your part correctly, using appropriate
tools and using good technique for drilling.
HTH.
Regards,
Robin
"Robin S." <[email protected]> wrote in message
news:qiDDd.65713$P%[email protected]...
>
> "Lloyd E. Sponenburgh" <[email protected]> wrote in message
> news:[email protected]...
>
> > Drilling with a twist drill in a drill press is not a suitable way to
get
> > _perfectly_ on-center holes in anything.
>
> Indeed there is no such tool that exists...
>
> > then re-index (or re-check
> > your index of) the workpiece,
>
> Why do you recheck after drilling? If an axis of the mill is not moving
> while you are cutting, it must be clamped - always.
Yes. Just 'checking' never hurts a precision job.
>
> > and "drill" the hole with a fly cutter,
>
> Perhaps you mean, "boring head"?
Ummmm.... Blush... yep...
>
> > bits drill more than two thousanths over their miked-out size, they need
> > regrinding to center the cut.
>
> This depends on the diameter of the drill, of course...
>
>
"Grant Erwin" <[email protected]> wrote in message
news:[email protected]...
> All of this supposes that your drill press table is at precisely right
angle
> to the spindle axis, and that your drill chuck has zero runout, neither of
> which is likely true, especially if you're using something you bought at
> Home Depot.
Oh, so next I 'spose you'll say it was foolhardy of me to bid on doing work
for NASA with a Shopsmith??
;-)
<[email protected]> wrote in message
news:[email protected]...
> If you get better results when the drill press is running I think you
> have excessive runout in the quill.
> Put a long bit ,largest diameter the chuck will take, turn drill press
> on. Do you see any wobble?
> If you have a dial indicator and a length of drill rod, you can check
> runout better.Sometimes the chuck can be at fault, though probably not.
> mike
>
Drilling with a twist drill in a drill press is not a suitable way to get
_perfectly_ on-center holes in anything. A) any twist drill will tend to
cut from a few tenths to a few thou oversized - partly due to lost motion in
the system and imperfect grinding, and partly due to false edges and chips
abrading the hole sides, and B) because any but a really stout drill that is
_perfectly_ ground will tend to wander a bit during its cut.
When one must have holes centered to within a few "tenths", you need to
pre-drill the hole a few (say 15-20) thousanths undersized (for chip relief
and fast stock removal) on a milling machine, then re-index (or re-check
your index of) the workpiece, and "drill" the hole with a fly cutter,
finishing with a reamer.
For most work, this sort of accuracy isn't necessary. If your drill press
spindle has more than a half-thou of runout, it needs servicing. If your
bits drill more than two thousanths over their miked-out size, they need
regrinding to center the cut. Short, stiff bits tend to wander less than
long flexible ones.
LLoyd
Your answer below is right on, however, please tell me what is wrong with
this amateur approach.
Center punch the material, rather deep. Enlarge by using a centering drill
in the drill press, BUT, assuming the project is quite small (one or two
pounds) let it float on the table and have it center itself as you start
drilling. You seemingly end up with no drill bit deflection and, I assume,
a hole that is quite close in location to your initial center punch.
I know that I am a mere amateur, but it seems like every time I fasten a
product to the table, I end up with drill bit deflection. When it is light
enough to float and self center, I get better hole location.
Ivan Vegvary
"Silvan" <[email protected]> wrote in message
news:[email protected]...
> Doc wrote:
>
>> Looking for any tips/tricks for drilling a hole w/a drill press that's as
>> close to dead-center to a specified point as possible.
>
> First tip: use an awl or center punch (depending on whether it's wood or
> metal you're drilling) to mark the precise location of the hole first.
> Even with a brad point bit, it's difficult to prevent drills from
> wandering
> off the target when they enter the material. The smaller the gauge of the
> bit, the worse the problem is.
>
> Second tip: depending on the nature of the work involved, you may be able
> to use a cross-slide vise for fine positioning of the work relative to the
> bit. They only work on stock that can fit inside the jaws, but they are
> quite useful to have when precision matters.
>
> Something like this:
>
> http://www.grizzly.com/products/item.cfm?itemnumber=G1064
>
> Now, whether you have one of those handy gizmos or not, position the work
> (with the hole locations pre-punched), then pull down the quill with the
> motor off. Listen for a plinking sound, and watch with hawk eyes for the
> slightest bit deflection. If the bit is deflecting to enter the dimple,
> your hole won't come out right.
>
> I find it helpful to rotate the chuck by hand to position the flutes or
> other cutting edges in a way that allows a clear view of the very tip of
> the point in relation to the dimple. Repeat the process of making fine
> adjustments to the X and Y axes and then checking with the quill until the
> bit enters straight and true, then drill the hole.
>
> This process is tedious and time consuming, but if there's a better way to
> ensure a hole as close to perfectly placed as possible with a drill press,
> I haven't discovered it.
>
> --
> Michael McIntyre ---- Silvan <[email protected]>
> Linux fanatic, and certified Geek; registered Linux user #243621
> http://www.geocities.com/Paris/Rue/5407/
> http://rosegarden.sourceforge.net/tutorial/
"Doc" <[email protected]> wrote in message
news:1ajDd.2352$%[email protected]...
| Looking for any tips/tricks for drilling a hole w/a drill press that's as
| close to dead-center to a specified point as possible.
|
| Here's what I've been doing - I have the position marked with graph paper
| that's taped to the workpiece. With the help of a magnifying glass, I
| painstakingly move the piece until the tip of the bit is aligned with the
| conjoining lines. By aligning with the tip I mean I view the tip both from
| the narrow or "pointy" persepective within the channel of the bit and then
| turn it 90 deg and look at the the wider perspective, and view it from the
| side and front to make sure I have it aligned with both the X and Y axis.
| When I finally get it so the tip is as centered as I can make it whichever
| way the bit is turned and in relation to both axis, I clamp the piece to
the
| plate of the drill press and drill the hole. However, on examination, the
| hole comes out obviously not dead center in relation to the graph paper
| lines.
|
| I've also tried aliging it with the drill running, going visually by where
| the "point" appears to be when the bit is spinning. I get somewhat better
| results this way but wonder if there's a more precise and dependable way
of
| achieving a centered hole.
|
| Thanks for any input.
Finding one of the optical center punches is the best way to locate the
center punch hole. After that, find the smallest drill bit your press will
handle and drill the hole with that, or at least a quarter of an inch or so.
The next thing is hardware you have to go look for. Double margin drill
bits. You work your way up using the previous hole size as the first
margin, or pilot bit. Not sure where to some, industrial supply, ebay,
aviation supply, or similar places.
I've also used what we call "core drills" which are special drill bits
made by turning down the first quarter of an inch or so of the drill bit to
the pilot hole you're working with, but obviously not too small. You still
have to sharpen the remaining edge of the bit. In doing this, I've started
with a center punch mark and worked my way up to a 0.3125" +/- .002" which
is even harder without the right tools.
By the way, double margin drill bits are awesome for drilling stainless!
I bought a bunch at Boeing surplus near Seattle and absolutely love using
them.
I use both center drills as well as punch, depending on whichever is
easier. Works out okay.
i
On Thu, 06 Jan 2005 22:43:09 GMT, Doc <[email protected]> wrote:
> Looking for any tips/tricks for drilling a hole w/a drill press that's as
> close to dead-center to a specified point as possible.
>
> Here's what I've been doing - I have the position marked with graph paper
> that's taped to the workpiece. With the help of a magnifying glass, I
> painstakingly move the piece until the tip of the bit is aligned with the
> conjoining lines. By aligning with the tip I mean I view the tip both from
> the narrow or "pointy" persepective within the channel of the bit and then
> turn it 90 deg and look at the the wider perspective, and view it from the
> side and front to make sure I have it aligned with both the X and Y axis.
> When I finally get it so the tip is as centered as I can make it whichever
> way the bit is turned and in relation to both axis, I clamp the piece to the
> plate of the drill press and drill the hole. However, on examination, the
> hole comes out obviously not dead center in relation to the graph paper
> lines.
>
> I've also tried aliging it with the drill running, going visually by where
> the "point" appears to be when the bit is spinning. I get somewhat better
> results this way but wonder if there's a more precise and dependable way of
> achieving a centered hole.
>
> Thanks for any input.
>
>
--
I second the recommendation of a centering bit to align
If drilling with thin bits, using something like a Starrett center
punch to pre-position the starting location would also help prevent
the bit from "walking" away from the point you want it to drill at
John
On Thu, 6 Jan 2005 15:03:11 -0800, "mp" <[email protected]> wrote:
>> I've also tried aliging it with the drill running, going visually by where
>> the "point" appears to be when the bit is spinning. I get somewhat better
>> results this way but wonder if there's a more precise and dependable way
>> of
>> achieving a centered hole.
>
>Have you tried using brad point or forstner bits? You could also chuck a
>centering bit to line up and clamp your workpiece.
>
>
On Thu, 6 Jan 2005 23:38:11 -0000, "Dave Baker"
<[email protected]> wrote:
>
>Turn a sharp point on a bit of thin bar in the lathe and use that in your
>drill chuck to centre on your graph paper. Ideally make it with a collet
>chuck or 4 jaw chuck to get it dead concentric. Then use a centre drill to
>start the hole before drilling right through.
He does not even have to turn anything. Most taps have conical
points. Just chuck a tap in the drill press and use that point as a
centerfider, then replace it with theintended drill bit.
"Lloyd E. Sponenburgh" <[email protected]> wrote in message
news:[email protected]...
> Drilling with a twist drill in a drill press is not a suitable way to get
> _perfectly_ on-center holes in anything.
Indeed there is no such tool that exists...
> then re-index (or re-check
> your index of) the workpiece,
Why do you recheck after drilling? If an axis of the mill is not moving
while you are cutting, it must be clamped - always.
> and "drill" the hole with a fly cutter,
Perhaps you mean, "boring head"?
> bits drill more than two thousanths over their miked-out size, they need
> regrinding to center the cut.
This depends on the diameter of the drill, of course...
"Doc" <[email protected]> wrote in message
news:1ajDd.2352$%[email protected]...
> Looking for any tips/tricks for drilling a hole w/a drill press that's as
> close to dead-center to a specified point as possible.
I was surprised at the number of replies I got in such a short time. It
occurred to me that I never said that I'm drilling into wood. I included the
metalworking forum to see if there overlapping skills. I suppose I could
clamp a piece of sheet metal over the spot and drill through it if that
would help.
"Doc" <[email protected]> wrote in message
news:1ajDd.2352$%[email protected]...
>
>
> Looking for any tips/tricks for drilling a hole w/a drill press that's as
> close to dead-center to a specified point as possible.
Switch to a brad-point? And stick the center point where you need it?