On 2008-01-06, Paul wrote:
DoN. Nichols wrote:
[ ... ]
Anyway -- it is now fixed.
Thanks DoN, it helps to know people in high places
Actually the first
email had all the files but instead of .txt the name was _txt and it
never made it into the directory. I then sent a second email with just
the txt file, this time named .txt, it did show up but the formating was
hosed. The third email had the repaired file but it had the same name
as #2...but all is OK now.
:-)
And yes -- Steve does know that longer lines (over 256
characters, IIRC) get truncated when being extracted. Another reason
for folding the lines before sending. (Out of curiosity -- what editor
was it which did you in?
I suspect that your finish problems pre VFD were coming in part
from the somewhat frayed belt which you have replaced.
The belt I suspect was the much thicker belt that was between the motor
and countershaft on the variable cone pulleys, but it could have been
the final countershaft to spindle cogged timing belt.
O.K.
I like the idea of putting a tach display into the project box
with the speed control pot -- and a panic button is not a bad thing to
add, too. I would drive the tach display from a magnetic impulse pickup
counting the teeth on the bull gear. That should give you pulses close
enough together so you don't have to wait for a full rotation or two at
the slower speeds before you get a valid reading.
This VFD has an output for a tach, scaled either for a 1ma meter or some
strange 8 volt square wave signal. Your idea of a tach pickup on the
spindle is better as it's actual feedback and not what the drive merely
thinks the speed is based on it's output.
Obviously, I would need to sense the spindle in some way, since
I am retaining the step pulleys. The alternative would be a standard
meter movement and drawing multiple scales on it. :-)
When I put a VFD and three phase motor in my 5418 I won't have
to do as much work. I'll keep the five-step pulleys for when I need
really slow operation at high torque, or really fast operation at low
torque, with most changes being done with the speed control pot.
That's one reason I went with a higher horsepower motor, and the thing I
think allot of people don't take into account when going the VFD route.
The motor being a basically constant torque device has much lower HP at
lower speeds. That is one advantage of belts or gears for speed reduction.
Certainly I will be upping the HP -- from 1.5 HP to 2HP in the
lathe. Note that you would have an effective gain in HP even if you had
kept the same motor HP -- because those vari-speed pulleys do consume a
lot of extra HP. This is why the vari-speed J-heads on Bridgeports are
2HP, while the step pulleys are 1 HP or 1.5 HP.
The pot is scaled to give 280 to 2000 RPM in straight gear, and back
gear divides that by 7, this basically replicates the original speed
ranges produced by the varidrive.
O.K. This is reasonable -- but I'm looking forward to being
able to go even lower in spindle speed -- for when coarse threading to a
shoulder. :-) (Though my reaction time is pretty good so far when
doing that.)
I presume that the project box was one of the die-cast zinc
ones? They can be quite useful -- even though Frys is a long way from
here. :-) (But -- there are local vendors who carry them.)
Yes, some sort of zinc alloy, actually a nice example of the diecasting
art, thin sections yet nice and straight, and a good surface finish as
well. The other impressive thing was the 6 cover screws were not self
tapping but tapped holes.
Yep -- sounds like what I have used in various sizes.
Fry's built a store in my area 2 or 3 years ago, it's about a 30 minute
drive but if we're in the area anyway I usually stop.
I think of Fry's as being somewhere in California. Is that
where you are?
Enjoy,
DoN.
--
Email: | Voice (all times): (703) 938-4564
(too) near Washington D.C. |
http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---