On Fri, 17 Jun 2005 00:06:01 -0400, Joseph Gwinn
wrote:

In article ,
Gunner wrote:

On Thu, 16 Jun 2005 09:32:03 -0400, Joseph Gwinn
wrote:

In article ,
(DoN. Nichols) wrote:

In article ,
Joseph Gwinn wrote:
Another poster mentioned driving his drill press from a Variable Speed
Drive (VFD) to slow things down to a speed suitable for tapping. I'd
like to look into this, but don't know which makes and models of VFD are
suitable. When I search on "variable speed driver", I get a flood of
large industrial units that far exceed the needs of an ordinary drill
press. So, what makes and models should I look into? TIA

First off -- does your drill press have a three-phase motor? If
not, forget the VFD idea, unless you are willing to swap in a
three-phase motor.

No, it's single phase 110 volt 60 Hz.


An alternative, as long as talking about swapping motors, is a
DC motor and controller. Those are particularly good at low-speed
torque.

I did think of that, but needed the comparison.


Perhaps some details about your drill press would help.

It's a cute little Delta DP350 12" bench drill press that was on sale
for $200 at Rockler, which really serves woodworkers, not metalworkers.
I'm guessing that Rockler bought a bunch of DP350s, only to discover
that woodworkers don't want T-slot tables on their drill presses, and so
put them on sale. A 12" bench drillpress is a bit small for woodworking
too, but it's convenient for much of what I make. Although the table
could be larger.

[snip]

Given that the DP350 has mechanical variable speed, a slower
constant-speed motor could well suffice.

Of course, the solution should not cost more than simply buying another
drill press.

Joe Gwinn

Put a 1/3-1/2 hp DC motor on it with one of the Minarick controllers
one fo the posters here has been selling and you will have something
you can control well enough.

Now that I think about it, it may not be practical to replace the motor,
as its shaft may be long and specially adapted to receive the
variable-speed pulley. I'll need to look into this. It's time to oil
those pulleys anyway.

It occurs to me that it might be a good option to buy a belt and step
pulley drill press, but with a three-phase motor, plus a VFD, to achieve
convenient variable speed. This may be cheaper, and somewhat better
than the mechanical variable speed approach, especially in speed range.
One can always change the belts and pulleys to set the general speed
range without great loss of torque. The variable-speed drive drill
presses are quite a bit more expensive than non variable speed, and this
may pay for the VFD all by itself.

Reaction?

Joe Gwinn

I rather like step pully drill presses with a VFD, rather than a
variable speed drill press or a VS drill press with inverter for those
reasons. Same with a milling machine.
Far less complicated, less stuff to need to maintain due to wear and
the ability to simply change to a smaller or bigger pulley for
maintaining torque at variable tapping or drilling speeds is hard to
beat visa vis cost.

Stick a S&D drill bit, 1" or bigger, and the average VFD poops out
down there at low rpms, but simply change to the proper pully size,
and fine tune your vfd and voila..a hogger.
The rest of the time, using the medium pully and the VFD and you have
good speed and torque ranges for most drill sizes.

YMMV of course.

Gunner

"Pax Americana is a philosophy. Hardly an empire.
Making sure other people play nice and dont kill each other (and us)
off in job lots is hardly empire building, particularly when you give
them self determination under "play nice" rules.

Think of it as having your older brother knock the **** out of you
for torturing the cat." Gunner