emco 5pc spindle motor help

[hutchison]

hi all,
 i'm needing some help on modifying my lathe spindle motor, i'm not sure if im in the right place to ask please let me know and move as necessary (new user)

 the machine is an emco compact 5pc lathe, and at the moment uses a .75kw 240v motor, i'm not conversant with electronics so please be gentle!. Ive just converted this machine to run mach3 using eugenes conversion (thankyou eugene) and your software here thankyou all, i'm very pleased so far and impressed with the functionality of mach.  but..  while imagining screw cutting op's / parting and general turning the speed of the carriage for threading at 2400 rpm would probably go through the shop wall.    i'm a time served toolmaker/machinist like most on here i would imagine... having to change belts half way through a job is defeating the object of putting feet up!.

 i need some advice here,  i need a quality spindle drive motor and drive equipment to interface with mach3  so i can utilise mach3 and the machine as a machinist intends        i would like to detail the steps here once complete

where to start?

[zarzul]

Hutch,

I have converted two machine spindles but not a EMCO.  Is that an AC or DC spindle motor? 

 I did a D&M labvolt machine, just put a new DC motor controller in,  you can pick these up on Ebay,  KBIC or others.  They have a voltage 0-10v input control for the speed and a contact input for starting and stopping.  The 120v models output upto 90vdc typically,  the 240v models output 180vdc.  The other one I did was a 7x12 mini-lath,  removed the motor and put a 2 1/2hp treadmill motor on it with a KBIC dc motor controller on it also. 

Did you use the conversion detailed in Digital Machinist?  Is that a lathe or mill?  There is also an article in the same  magazine on converting a emco compact 5 pc lathe, using all of the old hardware.

Arnie

[hutchison]

hey arnie,  yup i used the lathe conversion in the digital machinist article, its basically removing a chip and soldering 8 jumper wires..  astoundingly easy,  it does not involve changing any of the original motors / boards its almost plug and play. although it dosent convert the manual spindle control and belt/pulley drive.     i'll get the details off the motor tommorow i believe its a 240v a.c straight from the mains with contactor type control via a rotary switch, very basic!.


i have the emco pcmill50 aswell which was the newer version of the F1. that mill conversion was covered in that series of magazines but i can get by on the emco pcmill50 as it has a win98 interface so i'm coping with cad/cam translations o.k, ideally yes i'd love modern control with the mill50, but for now i'll have to get by.

i want some extra power from the lathe spindle, and also some extra speed, and just 'control' of it would be o.k i.e spindle on/off auto, and rather than building a relay box, id want mach 3 to control it all with pulses.   the standard motor HP is around 1.     i want maybe 2hp/1.5kw which is a lot for a tiny lathe!.. but should see me good for parting steel with ease

[zarzul]

You might want to consider going with the treadmill DC motor.  I believe the DC motors give you more constant torque over their speed range.  They are fairly compact and cheap.
Couple that with a regenerative ir comp dc motor chopper drive, and a pwm to v converter, then you would have full CNC controlled spindle, speed, stop / start.  The regenerative drives
can stop on a dime and the IR comp gives them a boost when loading the spindle to maintain the speed constant.
I picked mine up on ebay, drive and motor for less than 100 total.

[hutchison]

ok, whats regenerative and non?   whats IR comp? and chopper drive!, and erm..  pwm to V convertor, sorry for the dumb questons, i'm not electrically knowledgable to this degree

[zarzul]

Hutchison,

I didn't mean to sound too techie.   I just figured anyone who would breakout the soldering iron and have a go at their machine would be an Electronics guru.

regeneration stops the motor by turning it into a generator and driving the kinetic energy back into the controller,  the end result is if you spin the 3/4 turn speed pot on my lathe's regen motor controller from full speed to zero the motor is stopped before you take your hand off the pot.  Nice feature for safety but can be stressful on machine or parts.  Not required.

IR comp is a feedback feature, kind of like a closed loop speed controller where you call for a speed, actual speed feedback is sent to the controller and the controller will boost output if speed drops to maintain it at a constant speed.  The IR comp is looking at current and resistance to provide the same response and is very close to closed loop, but you don't have to pickup any outside signals because the drive controller already has the IR built in.

Chopper is just a description of how the power is converted from AC to a variable voltage DC,  the full AC wave is rectified at the highest speed setting (highest DC voltage) and only part of the full AC wave is rectified at a lower setting,  (part of the wave is chopped off).

PWM to V converter, a circuit that takes a pulse (mach3 speed control signal from the parallel port) and converts that pulse signal into a Voltage (a lot of the controllers will accept a 0-10 voltage signal as the speed demand signal)  The PWM signal is a fixed frequency with a variable width (on duration).


I took a look at that Fincor drive  http://www.saftronics.com/PRODUCTS/DCDRIVES/2330/2330L.htm, it looks like it would work fine, maybe a little pricey but it probably cost $230 usd new.  It may not have the option of the 0-10 volt signal input,  if you can get the full model number and look at options in the manual.

[hutchison]

electronics guru haha, made me titter, i just liberated my machine as i do with most mechanical stuff!.    broken into laymens well   
 pulse width mod to voltage, i can understand that logically thinking. i can sympathise for not wanting to stop the motor quick, i guess its handy for square jobs that need coding to right side up / quick spindle brake on contract work, not necessary for round / home work!.   i like the IR comp feature, thats another on the list.

im not sure about regenerative or non yet, can i get a 'non-regenerative chopper drive with IR comp? sounds like the best of both worlds?
the spindle bearings and belt drive of such a system would take load there, i think it runs on 6309 bearings, assuming i would employ a decent timing belt and pulleys it cant be too much to replace.  can the drive handle the return of the power?

[hutchison]

i took the details from the existing motor:

single phase asynchronous
2650rpm
2.1 amps
240v
50hz
23-60% vde
0.3KW

i took these motor details from the manual:
power @ 60% duty = 800w
supply 220v/50hz/3.3A

just for further ref, feed motors,
rapid700mm/min, (although i'm running 498mm/min max through mach right now)
 5 degrees/50ncm/0.37lb/ft
feed power approx 1000N / 225lb/ft. 

[bigbigjimbo]

Hi,
Where can I get a hold of this magazine that shows the conversion for the compact 5 does anyone have the instructions how to do it?
Jim

[zarzul]

Jim,

It is the digital machinist, a publication by the same folks that do the home shop machinist and machinist workshop,  villagepress.com

Arnie