Field Voltage for Hendey T & GMkrs' Lathe

Does anyone know what the field voltage on a Hendey 9 x 24 should be. My new lathe has the original motor, but a solid state drive. Wired it up today and the motor runs, but won't get over about 800 rpms. I am getting 236V out of the controller. I have 200ish volts on the field and have the option of changing to 100V. The motor name plate is no help ( at least with the field voltage). Would it hurt to try?

Thanks,

Charlie

Born2L8:

The drive system in your lathe was used by
the Barber Colman Company and is known as the
Louis Allis Select-A-Spede. In this system, the
line voltage is run through a full wave rectifer
to suppy the DC motor. The actual field voltage is supplied by a magnetic amplifer, whose core
saturation level is used to maintain the motor
speed under various load changes. Your motor
should have four leads, one for the armature, one
for the field and two for the shunt winding.

With the original control panel, 230 volts DC
would be available as field voltage. The speed
settings are controlled by two wire wound resist-
ors. While no voltage charts are available, a
pencilled note on the schematic indicates that a
200 to 205 volt range was used to set the low
speed, with the speed regulator in the center
position. This would give a base speed of 700rpm
and was done with the low speed resistor. The
high speed resistor was then adjusted, no field
voltage was listed for this setting.

The three position drum switch is used only
to (R)reverse, (S)stop and (F)forward. A separate
push/pull switch is used to stop and start the
motor.

There were many variations of hook-ups and speeds for the ON series of Select-A-Spede motors,
I am just giving you an overview of the basic sy-
stem.

Hendeyman

Dang, now that's service.

I'll take the liberty of saying thanks for the info hendyman.

Phil

Thanks Hendeyman,

I have none of the original drive parts, except, of course, the motor. My drive is a PentaKB 225D.
Using it only, I can only select between 200 and 100 volts to the shunts. I will connect it to the 100V side tomorrow. If it starts to runaway, I'll shut it down and we'll try to figure something else out.

Should have my 9 belts for it tommorrow, too. Maybe cut chips soon!

Charlie

I changed the shunt voltage to 100V and the motor spools up where it ought to be, I think. I have no tach. Don't know about torgue and am going to assume the drive will take care of that. This is a regenerative drive and will go from full forward to full reverse in about 3 seconds. That might be handy somewhere down the line. I don't know what these drives cost, but so far I like them.

Charlie

First chips today.
This is one sweet machine.
Quiet, smooth as silk, and I love that threading set-up. Chamfering is a treat, too. I will install a 3-way switch so I can select between the 100V and 200V to the shunts. I think that will give good low end torgue and speeds plenty high enough for me.

Charlie

Installed switch tonight.
Note to self (and any others who may try this):
Do not switch while the motor is turning, even if the stop button has been pushed and the motor is almost stopped.
Big pop, little smoke.
Blew the line fuse and hopefully, nothing else.
Might be due to the fact that switch is an ON-OFF-ON type so, for an instant there was no shunt voltage.

Charlie

No such luck, but looking on the bright side I got to learn what the drives costs. $385.00 for the chassis with none of the "user interface" stuff. Surely I didn't blow up that stuff.

Charlie

Born2L8,
Do you have just two speeds - 800 rpm with shunt at 200 volts and 3000 rpm at 100 volts? Or is there some speed control by varying the shunt voltage between 100 and 200 volts? Thanks,
Browniesharp

Browniesharp,
I have variable speed in either full or half shunt voltage. I assume this is accomplished by varying the armature voltage or current. I purchased a "Tachulator" but have not installed it yet. I think the top end with 1/2 voltage (100 V) will be between 2-3K. I will disconnect my switch so I don't fry another board. I think some adjustments to the drive will improve the torgue characteristics.
I hope to get the drive and tach going this weekend. I've been sidetracked by putting in a new (to me) CNC router. Since the wood pays the bills, the lathe had to take a back seat.

Charlie

I got the new drive and the tachulator http://mkctools.com/tachulator.htm installed.
with 100V on the shunts I am only getting about 1100 RPM. While this is good for 90% of what I would need, I would like to get a little closer to what this lathe was designed for. I am now in uplowed ground. Any help would be appreciated.
Turned an 18"ish test bar, and the thing looked like it had been ground. The only noise was the barely audible sound of the sharp brazed tool slicing 4340PH and a little belt squeak. I also liked how the finish splits up the colors of the flourescent light.

Charlie

Born2L8,

Don't take offense, but perhaps it is time to replace that drive with a VFD. My Hendey tool & gage makers lathe had one of the more advanced electronic drives (similar to the Monarch 10EE WIAD with 2 C16j and one C1K tubes). The power supply didn't work when I got the machine, so I replaced it with a sensorless vector drive. It's a pleasure to use operating from 1 rpm in backgear to 3000 in direct drive.

My machine duplicates your's in performance. A 8" long steel round unsupported in a three jaw chuck also had a "ground" appearance when using a sharp HHS tool at 300 sfm with a light cut and fine feed. Best I could measure was 1/2 tenth TIR with a taper of a couple of tenths over the 8" even with visible bed wear.

My only problem (besides the bed wear) is an annoying whine at speeds above 600 rpm which sounds like it's coming from the spindle bearings. But they don't get hot and would bad bearings produce a finish as I have seen?

I found a drive that would work. It is Baldor's
20H and the price was only $3,650.00! I've got a nearly new 5hp 3ph motor just collecting dust, so the VFD is probably the way to go.

Charlie

I bought a new Sumitomo NTAC-2000 5hp sensorless vector drive on the Bay for $100.00 + $20.00 shipping. The motor that I have is a Siemens 1750 RPM. The spindle turns at close to motor speed in belt drive. Can I safely turn this motor at 150% of base speed?

Charlie

I put some pictures of the lathe on this parrallel thread.
http://www.practicalmachinist.com/cgi-bin/ubbcgi/ultimatebb.cgi/topic/2/2270/2.html?

Charlie