In article ,
Gunner wrote:
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:
[snip]
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.
I looked at it this morning. It's a long shaft (~6 inches) with a long
keyway, plus two circlip grooves between which the variable pulley
mechanism sits, all metric. Definitely custom.
In another posting, Gunnar suggested machining an adapter shaft, which
could be done, but I don't know that I want to go to the trouble.
Instead, I'm thinking of getting a VFD that's big enough to run this
little 1/3 HP motor off one phase when I'm using the little drill press,
and this same VFD to run a larger 3-phase (probably a floor model) drill
press to be named.
The other issue that's developing in the DP350 is belt wear. The inside
of the housing has a layer of rubber dust already, and I've only had the
unit since 29 April 2005. I recall some complaints on Amazon about the
belts wearing out too fast, and some people saying that they had not had
that problem. I suspect that the cause is the sharp edges on the inside
of the pulley cones, where the facing cones mesh. The belt is
perpendicular to and runs over these sharp edges; this cannot be a good
idea. I plan to take the drive apart and round those edges with a hand
file. The cones are made of zinc-aluminum die metal.
The belts cost $38 from Delta; while $38 seems a bit much for a belt, I
did buy one, to have a backup. What Delta provides is a Tru-Power
V13x860.
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 pulley 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.
This was my instinct, but I'm glad to hear confirmation.
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 other problem I'm having is large drill bits and countersinks
slipping in the chuck. With the original keyed jacobs-style chuck, it
was not possible to get it tight enough by hand, so I used a six-inch
length of 3/8 black iron pipe as a key extender. This does work,
although the key arms were right at the edge of bending, or a little bit
over the edge, and the whole operation was pretty time consuming.
So, I bought a Phase II keyless 1-13mm chuck (Travers # 63-099-024, $32)
and it's a lot faster, but it too will slip on the larger stuff. I got
a surplus spanner wrench that allows me to hold the top (narrow) knurled
ring while hand tightening the body of the chuck, and this works for all
but the MA Ford 5/8 inch countersink (which has a very smooth shank).
There is noticeable added tightening when using the spanner.
I think I'll roughen the shank of the MA Ford countersink with flooded
wet-dry sandpaper. It really doesn't need to be polished.
I'm wondering if a better chuck would help. I looked at the
ball-bearing jacobs-style chucks, and at the more expensive keyless
chucks, such as those made by Rohm. Any opinions?
The rest of the time, using the medium pulley and the VFD and you have
good speed and torque ranges for most drill sizes.
YMMV of course.
Yes, but I gather that you have direct experience with this setup, and
it works as one might expect and hope that it would. Said another way,
there were no surprises. This is often the key.
Joe Gwinn