In article ,
wrote:
Greetings,
Having a need to drill some stainless steel, I am looking for a small
drill
press. I have done some research and gather that bigger/more
sturdy/heavier
is better, but it costs more... so I'm concentrating on 12" bench-top
models,
Note that the 12" models can drill holes centered only 6" from
the nearest edge of the workpiece. If this is sufficient, fine.
Otherwise, consider larger, even if you are over your price limit.
and the arbitrary price limit is $200, although I would consider
raising it
if all that can be found under it is useless for drilling stainless
(up to
1" holes).
You don't state which stainless steel you intend to drill, but
let's assume that it is the one of nasty reputation, 304. Looking in my
copy of _Machinery's Handbook_, I find, for 304 SS, and uncoated HSS
drills, the SFM (Surface Feet per Minute) for really pushing the drill
is 75 to 65 SFM. Carbides are 520 SFM for hard, and 310 for tough, and
coated carbides (tough) are 625 SFM.
Note that carbide drills in that size are *very* expensive, so
we'll calculate based on HSS. And I don't think that there are any
Silver & Demming (e.g. reduced shank) drills, in solid carbide, so HSS
is the most likely one for you.
Now -- for the fastest for HSS was 75 SFM. So -- the RPM for
that maximum SFM with a 1" drill bit is about 286 RPM. And this is
pushing a drill at a speed which will wear it out a bit faster, but
will produce more parts (these speeds are for industrial production, not
hobby work). So -- this will limit your choices
Even slower speeds would be nice.
[ ... ]
o More power is better. Some drill presses under $200 have 2/3 HP
motors,
And some vendors lie more about their motor horsepower than
others do. Some are running the motor so close to the edge that they
*will* burn up in your tasks.
Note that with some stainless steel variants, if you can't push
the drill hard enough, it will work-harden the stainless steel, and the
subsequent drill bits won't be able to re-start the cutting.
You can get away with smaller motors with more speed reduction,
and this may be what you will need to do for your work.
others have much less.
o More speeds is better. Particularly for large holes in tough
materials,
low speeds are important.
*Very* important for what you are trying to do.
Many less expensive units have 5 speeds, a
few
have 12 or 16 (1 versus 2 belts). None that I could find in that
price
range had variable speed. Some have a low speed of 540, others 280,
620,
500, etc... How important is it to concentrate on the lowest
possible
speeds for large holes in stainless steel?
How many drill bits do you want to use per hole? Even the 280
RPM one is pushing things a bit for hobby work.
o The downstroke is usually between 2.x to 3.x inches, is this
sufficient
for serious work?
How thick is your stainless steel? You will want a minimum
stroke of probably at least a half inch longer than your workpiece
thickness with a 1" drill. You may need more if you have to lift the
workpiece out of fixturing, or if you need to change the drill bit
without disturbing the workpiece.
I presume that longer is better as long as the
machine
is built right and the drill bit does not wobble. Of course the
runout
number is something that I haven't seen in any description.
You won't. Most of the machines you have found are various
flavors of imports, and are variable depending on the phase of the moon
when they were constructed.
o Chuck capacity: bigger is better. The 1" bit I already have
requires 3/8
so I would say 1/2" is minimum (and common), 5/8 is better.
I think that a 1" Silver & Demming bit (reduced shank) will
probably put too much stress on a smaller chuck and shank.
Ideally, for this size, I would suggest getting drill bits with
a Morse taper shank to fit the drill press spindle directly, without a
chuck being involved at all. Stainless steel is *tough* stuff, and you
are proposing large holes. And most of the drill presses within your
budget will have only MT-2 shanks, while a 1" drill is happer with a
MT-3 shank.
[ ... ]
The Delta DP300 and DP350 are a little below and above the $200 mark,
but I
have read bad things about the quality of the Delta equipment. The
Fisch
Precision Tools DP2000 has one glowing review and fits the price limit
as
the shipping is included. The motor is kind of small (1/3hp) and the
lowest
speed is 500 (6 speeds). Does anyone have opinions on this model and
the
Deltas?
*Old* Deltas (made in the USA) could be very good machines.
What you get today (new) is yet more imports, and probably tailored for
woodwork, not steel.
The Central Machinery 38142-6VGA available here
http://www.harborfreight.com/cpi/cta...emnumber=38142
looks really good: big motor, 16 speeds (240-3600: the biggest range I
found), chuck capacity to 5/8, "heavy duty", etc... Opinions?
The speed is a benefit. Plan to replace the belts fairly soon,
as they tend to have rather marginal belts, and you will be loading it
seriously.
The spindle is only a MT-2. I know, as I have a floor-standing
version of this which is now perhaps 19 years old. I don't use the
original chuck. I no longer have the original belts, and I don't push
it anywhere near as hard as what you plan. The belts are not really
wide enough to transmit the torque which you will need to do this work.
(But neither are they on most of what you are looking at, and I don't
have time to visit *all* of your URLs.
At the moment, I'm leaning towards this one. Are there any show
stoppers here?
One potential one that I see. This -- like mine -- has a round
table which is clamped by a hollow shank which is perhaps 1-1/2"
diameter. When drilling anything, you want it either clamped down to
the table, or clamped in such a way that the column will keep it from
spinning. If you are clamped down to the table, the center clamp on
that rotating table may not be sufficient to keep it from spinning,
which could make things rather exciting.
Anyone with direct experience?
I forget who they called themselves when I got mine, but the
fact that I haven't broken down and gotten a serious US made one so far
says that overall this one is pretty satisfactory. The belts *will*
slip under hard drilling, and the belt tensioning device is marginal at
best.
Anyway, this is already getting too long without getting into more
brands/models. Does anyone have other recommendations?
Yes -- find a used machine tool dealer, and look for a serious
drill press -- with at least a MT-3 spindle. Plan to drive the drills
directly -- no chuck involved.
Expect that such a drill press will also probably need three
phase, so plan on building a rotary converter -- or hooking up VFD,
which will allow you to get even more speed control, as you can control
the motor speed directly, to supplement the belt reduction.
I would also be grateful for pointers to lowest cost vendors. I have
checked
amazon/tooldigger, northerntool and harborfreight.
I don't think that you can do your proposed task with anything
*new* near your price range -- but a good used piece of equipment might
be available from the used dealers.
Give us a clue where you are located, and perhaps we can point
you to a used equipment dealer known to do things right in your
vicinity.
Good Luck,
DoN.
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