I am amazed at
the performance of this
little motor. It will drive the spindle from about 35 RPM to
about 1100 RPM just by turning the knob on the pot. In back
it will run from less than 5 RPM (the lowest my tach reads with
reflective segments per revolution) - that's 1 turn every 12 seconds -
to somewhere around 150 RPM.
crank the motor to full speed in back gear. What really
was that at 35 RPM in direct drive I could not stop the spindle by
pressing my hand on my 6 1/2 inch 3 jaw chuck as hard as I could
press! I have not actually done any machining yet, but all
indications are that it would actually work pretty well for almost all
I am not serious about leaving this motor installed on my
I really think I need a little more "serious" power source, but I think
motor would work great for my drill press.
What I did decide, though, is to replace my old motor with a 3 phase
motor and a VFD (variable frequency drive). A VFD takes
phase or 3 phase power, in my case it will be 115 volt single phase
power from a wall plug, and
converts it into 220 volt 3 phase power. The big advantage is
that it will output from 0 frequency to whatever top frequency
you program. Most motor manufacturers recommend not going
150% of the nameplate rating, and you risk overheating the motor at
very low speeds where the built in fan is ineffective, unless you add
an external fan. This
means that for a 1725 RPM
motor, you can run it from near 0 to around 2600 RPM, producing full
up to about 1800 RPM with a drop in torque, but constant horsepower
above that. In summary, this setup and the sewing motor are
similar. Both have a VFD (built in on the sewing motor) and a
multi phase motor which can vary its speed with the turn of a
pot. My new setup is of a more substantial construction and
horsepower, but a lower overall speed range. Actually the VFD
the capability to run a motor faster than the 4500 RPM of the sewing
motor, but I would not trust my motor to hold together at 5700 RPM, the
maximum the drive could turn it.
I decided to go the 3 phase motor/ VFD route after comparing the
price/value ratio for new standard
motors, overhauling my existing motor, and a super deal on a VFD and 1
HP 3 phase motor from Dealer's Electric. They have a
Teco/Westinghouse VFD, which is a well known, quality brand, coupled
with a new 3 phase 1 HP, fully enclosed motor for under $200!
it's only a penny under, but it is
under. Of course the shipping
really gets you! I am excited to see how this new system
Everyone who has a VFD system seems to rave about it.
While I was preparing for my new motor, I removed the top countershaft
to make sure the pillow block bearings were OK. What I found
that one bearing was very rough, and had obviously seized up at some
time. The shaft under the bearing was badly worn. I
ordered all new pillow block bearings and a length of 3/4 keyed
shafting to totally replace these parts. The pulleys are
The end of this shaft, where the other pillow block bearing was, shows
wear where the bearing must have seized up at some time. I
all new parts.
Law of Multiplying Tools
As is so often the case with tasks like this, I will start a project
and pretty soon I find a problem. I try to fix the problem
find I cannot without making or buying yet another
this case it was a
defective pillow block on the countershaft. When I tried to
remove the pulleys and bearings from the shaft with the tools at hand,
I couldn't. I
to press the old parts off the shaft so I can use the pulleys on the
new assembly, but my tiny arbor press does not even begin to have the
size capacity, even if it has the force capacity, which it probably
does not. I tried prying with bars and levers without
success. I was
afraid to use a lot of force for fear of breaking a pulley
flange. The bottom line is that I went to Harbor Freight
Tools, with a 25% off coupon in hand, and bought a 12 ton shop press
for under $100. After about 30 minutes of assembly putting
press together, I
successfully disassembled all the parts from my shafts in just a few
minutes. It works great! I have had my eye on this
for a long time, but needed a "special event" to trigger my purchase.
My little arbor press has a maximum height capacity of 4 inches with a
throat depth of 3 inches. It is very restricted to the work it
can handle. However, the price was right!
My new shop press has a 12 ton load limit with very large height and
depth capacities. And it's price wasn't all that bad!
I just realized
why I had to use a press
to remove the old pillow blocks and pulleys when the parts all slip
easily onto the new shafting. I used Loctite Bearing Mount,
is now called Loctite 680, on all the bearing and pulley
This fills all the gaps and removes any possible play or backlash in
the assembly. I have just ordered a new bottle and I plan on
locking all the parts of my current assembly when I receive it.
and VFD arrive! (2/11/14)
A short while ago my new motor and VFD arrived. I have opened
them, but not tried them out yet. They look great!
Here is the new 1 HP 3 phase motor for my lathe, and the Variable
Frequency Drive (VFD) to control
it. I think it is amazing that such a tiny control box can
handle all the power for that huge motor, as well
as varying the speed from about 0 to 3 1/3 times the nameplate speed
(although most motors should not
be run that fast).
I tried out the motor and VFD today. I used a
10 foot length of 4
conductor 14 ga wire I bought for this job. It is longer than
think I will need, and one gauge heavier (all that was available), but
I will cut it down after I determine my exact
requirements. After connecting the motor and a line cord to
the VFD, I carefully plugged it in and the VFD lit up
exactly as the manual said it would showing the line voltage for a few
seconds, then the initial frequency setting of 5 Hz.. I then
pressed RUN and the motor started very
slowly. I then slowly increased the speed. At about
there was a loud clunk and everything stopped. I
my previously double checked wiring and tried to figure out what
happened. As a test, I turned on my bench power supply to see
I had any
power, and had none. I then discovered the GFCI had
further testing I found that whenever I reached the 12 to 13 Hz range,
the GFCI tripped. It was too late to call the supplier
but figured I would first thing in the morning.
When I came in to my office, I decided to Google "VFD GFCI".
got many pages of hits, all of which related problems trying to run a
a GFCI protected circuit. It seems that the high frequency
switching in the pulse width modulated voltage control sends all kinds
of high frequency noise through the wiring and confuses the GFCI into
there is an imbalance in the line, causing it to trip. I
into a non-GFCI protected circuit and everything worked as the
manual said it would. WHEW!
I cleaned up the drive compartment under the lathe. It looked
terrible! It was dirty, and in an effort to quiet the
of the sheet metal panels surrounding the drive, my dad had painted
black undercoating to help dampen the vibrations. This
caused it to look dirty with large areas of black on gray. I
removed all the drive mounting trays and their support
frame. I then cleaned and painted the interior of the cabinet
and all the
parts I removed.
I used my CAD program to lay out the new arrangement of the drive
components. The location of the twin v-belt drive to the
required me to move the mounting frame to the left of its current
position. (I had moved it to the right when I installed the variable
speed drive). I plan on
re-installing the original step pulleys in place of the variable speed
pulley. As I never throw anything away (I actually do
had all the parts I took out in the early 70's. Even though I
installing a variable speed VFD controlled motor, I would like to be
able to choose the basic ratio. I can also move the large
up to the top countershaft and drive it directly from the motor,
bypassing the step
pulleys and the extra belt. I think this gives me all the
flexibility I need.
I don't have any records of the drive configuration before I installed
the variable pulley in the early 70's,
(and my aging memory doesn't help a lot) but I think it was somewhat
like this. I have moved the
mounting frame to the left from where it was for the last 40 years, but
about an inch to the right of its
original location. This gives me minimum shaft overhang of
the spindle drive pulley.
I can easily move the 8 inch pulley up to the top countershaft and
drive it directly from the motor, eliminating
one belt stage. I may desire to do this after gaining some
experience and selecting the best ratio.
photo on the left is the lathe drive as it was when I inherited the
lathe; the one on the right is after I converted it to a split pulley
variable speed drive
time after I completed these modifications, I found several old photos
of the lathe drive as it was when I received it and of how it looked
after I completed the variable speed drive modifications.. I am
including them here merely for historical purposes:
original cabinet lacked much in "curb appeal". Repainting the
cabinet interior and the contents will help a lot. On the
see the mounting frame installed after moving it several inches to the
will allow the various components to fit and align with
belts which are really the only hard and fast location. The
splotch in the center of the wall is a stack of rubber pieces
glued to jam between the sheet metal back wall and the frame (it used
to be 1
inch further left) to dampen vibrations. I added
a couple pieces to do the same, but later found it was no longer
It is obvious to me that this mounting frame and the two upper shelves
are not original Logan parts. Someone, probably my dad,
the factory configuration. I cannot figure out the
original Logan setup, as any pictures I have found on the web show
parts mounted on the
vertical frame members. There are no mounting holes in my
I mounted the motor and temporarily installed the two best of the
blocks along with the pulleys as a temporary setup. I had to
slot the mounting
holes of the motor slightly to align with the cast mounting slots in
the bottom shelf.
I cannot believe how quietly my lathe runs now! There is none
of the low frequency
rumble that used to echo in the sheet metal whenever the old
motor was running.
As it is currently belted, I can run from about 50 RPM to about 900 RPM
speed in direct drive with the allowable frequency range of the VFD
5 Hz to 90Hz. Back gear speeds are 1/6 of these.
The addition of the step pulleys will
allow me to adjust these speeds up or down.
My pillow blocks just arrived. Did you know you can buy
block bearings from Amazon? It only took a couple of hours to
my two countershafts all set up. I had one new belt that
for the cone pulley stage and a temporary 20 to 50 year old belt for
motor. It works, but will be replaced soon.
Here is my fully assembled drive system. It includes 4 new
pillow block bearings and
new shafting. The cone pulleys have been out of commission
for over 40 years, but
are still in excellent shape. All 3 belt tensioning rods have
been added, completing
the mechanical part of this project.
While I was waiting for my pillow blocks to be
delivered I wired up the VFD and a fused disconnect
box. I plan to get an enclosure for the VFD as
there is little protection the way it is designed. They are
supposed to be installed in larger boxes, but many people don't do
that, and just mount the VFD by itself. While I was at it, I
existing drum switch to control the motor in the same manner as when it
was connected to my previous motor. Now instead of
full motor voltage and current, it only controls a logic level of a few
or less. In looking for a shielded multi-conductor cable (I
wires for this function) I found a 10 foot Centronics type printer
cable in my garage. I have not had a printer using a
at least a decade, so I lopped off one connector, and sure enough, the
cable was shielded. As I said I only need 3 conductors - this
about 25! They were small at around 24 ga. I also
kept several other wires as
spares and cut off the rest. I also had a serial cable that
shielded with a lot fewer conductors, but it was less than 3/16 inch
diameter so I was afraid
of it getting snagged or damaged. The cable I used is about
and will not easily get pinched between parts.
I installed the VFD and the disconnect box on a board, leaving room for
the enclosure I will be adding.
I figured this was a good way to mount the items as well as allowing me
to wire most of it at my bench.
The duplex outlet is switched on and off with the main lathe power, and
will be used for my tach and
possibly for an AC power supply for my DRO's. This picture
shows the spindle running at 265 RPM
at a frequency of 35.0 Hz.
I decided to temporarily wire up my existing drum switch to control the
on/off/reverse functions as that is what I
instinctively reach for, and I have it now. I will probably
change it to start and stop buttons and a reverse switch shortly, it
is a simple matter. At this time, I am using the pot on the
drive unit to control my speed. I have a
10k linear Allen Bradley pot just waiting for me to mount and wire in,
but at this time, the VFD is as
handy as any place I have to mount it.
So far, I am very pleased with the ease of control, the speed range I
can set, and especially the quiet running.
of Plans 2/26/14
I ended up ordering a somewhat larger enclosure than I had
planned. The VFD manual indicated I needed more space around
the unit for
proper cooling. After seeing the size of my new enclosure I
decided it was foolish to have all the extra ugly gear for disconnect
and extra outlet showing, I could incorporate all that into the
itself. I ordered a two pushbutton machinery type on/off
switch and found a surplus porcelain cartridge fuse holder and the
class fuse the VFD manufacturer recommended. I decided to
VFD so the front panel protrudes slightly through the front cover of
the box. This still gives me access to the buttons and knob
setup and control, and lets me see the output
frequency, while protecting it from debris and accidental electrical
I cut the holes for the VFD and the on/off switch using my
mill. The large box is very
awkward to handle and setup. When I cut the large hole I had
to cut half from one
side, then turn the box around to cut the other. I guess I
need a larger mill! Or I
could have extended the head of the mill out further, but then I would
with a lengthy alignment process to put it back accurately.
I have mounted the assembled box. It looks so much better
than my previous
kludge! The on/off switch just came in and I was able to
finish this project.
at the mechanics (3/6/14)
I have noticed that it is very hard to adjust the belt from the motor
to the lower step pulley shaft, and that I had to get an exact length
belt for it to work. Looking at the geometry of the motor,
pivot point and the location of the pulleys I saw that the motor pulley
moved almost at right angles to
the shaft center lines, meaning that moving the motor a lot, tightened
or loosened the belt very little. This is a fatal situation
plans of an eccentric lever loosening the step pulley belt enough to
change ratios, as the motor belt would not let the motor lift.
I decided to totally remount the motor, hanging it from the middle
shelf and relocating the pivot to be level with the motor shaft for
maximum adjustability of the belt. Also, when I swing the
shelf to loosen the step belt, the motor just moves with it with no
relative motion between the two.
On the left you can see that the pivot point is almost in line with the
pulleys, so that there is very little change in the belt tension for a
large movement of the motor. In
fact, if the motor is lifted more than a few degrees, the belt starts
On the right, the pivot point has been moved even with the motor
centerline and now a small movement of the motor will have a large
on the belt tightness.
Also, when I move the middle shelf (top in this diagram) to adjust the
step pulley belt, the motor will now swing with it, with no effect on
its belt tension.
On the left you can see the center shelf with the added brackets
hanging down to provide a pivot for the motor.
On the right is the motor shelf with two brackets going up to complete
the pivoting mount.
I tried really hard to get a good picture of the final
assembly. It just cannot be seen
from outside the cabinet. I finally got this shot by holding
the camera at arm's length
inside the cabinet and shooting blind (one of several I
tried). It at least shows one side
of the combined brackets and the new raised pivot point.
As I stated above, I decided to keep the drum switch as my main
for the time being. It works well, but I really want to do it
right. I have ordered start and stop pushbuttons and a
switch. The VFD will readily accommodate these. I
plastic outdoor double outlet box which should have enough
room to mount these new controls along with a speed controlling
potentiometer. The box should fit OK on the front of the
headstock where the current drum switch is mounted.
March 19, 2014
milled out all the excess studs and the inner part of the conduit inlet
from the outlet box, mounted the buttons, switch, and
I made a hard-wood mount on the front of the lathe, attached the
control box, and wired it all up. A couple of changed
codes on the VFD, and it all worked correctly.
I made a mount from oak which attaches using the same holes which held
The finished control box is mounted and wired. You set the
direction of the spindle
using the Forward/Reverse switch on the upper left. You then
press the green
start switch and it runs. You control the speed using the
knob on the lower left.
To stop, you press the red stop button.
more changes 3/27/2014
Now that I have had a chance to use the new controls for a little while
I have found some things I don't like. The box hangs out
than I am comfortable with. There is no real danger as the
button which might be accidentally bumped is the stop button.
There is a small chance of bumping the speed dial and changing it, but
not likely. The biggest physical problem I have encountered
far is that if I try to use my 3 jaw chuck wrench on the front of the
chuck, the handle hits the box and cannot be turned. This is
small annoyance, but it bugs me.
I have been planning all along to replace the temporary bar which has
my DRO readout heads and my tachometer on it with an enclosed
box. It just so happens that I have an unused 8" x 8" x 4"
plastic junction box I bought when I was converting my electric truck,
but didn't use. I have decided to use it to mount the DROs,
tachometer, and the control switches in it. I will then mount
much smaller box on the front of the headstock with my emergency stop