Can anyone help me finish off this Compact 5 Conversion

[Pete92]

Hello folks. For the last year or so I have been converting a Emco Compact 5 MK1 to run on Mach 3 Software. I basically removed all the original steppers and control boards and built up a new unit using a kit from 'CNC 4 U'. I know probably not the best quality stuff but for what I'm doing it should be fine. http://www.cnc4you.co.uk/CNC-Kits/Stepper-Motor-Kits/Nema23-Stepper-Motor-Kit-4Nm-x-3-Axis

I got that up and running fairly easily getting both axis moving using the trial version of Mach 3.

Then it came to the spindle, which is where I am now stuck. I would like to control the spindle using Mach 3. The original Emco motor is an odd voltage so I am going to swap it out and use a motor I have from a college project: http://www.hobbyking.com/hobbyking/store/__37213__Turnigy_Aerodrive_SK3_6374_149kv_Brushless_Outrunner_Motor_UK_Warehouse_.html?strSearch=149kv I will run this with a 24v power supply.

My first question is how do I get the breakout board connected with the motor? From what I can gather reading other topics its to do with PWM. What components do I need and how do I connect them up to get the computer to run the spindle.

The next issue is once I have got the spindle sorted, how do I wire in the spindle rotary encoder. The lathe has the original encoder still attached, can I use this or do I need to swap it out for something more compatible?

Hopefully if someone can help me out with this lot then I can have my lathe up and running soon. Many thanks in advance.

Another little niggle is that there are no limit switches on the machine. Are these required or is there a setting in Mach3 to stop the axis when it has reached the end of its travel?

Many thanks,

Peter

 

[kvom]

The limit switch issue can be handled in Mach3 via soft limits. However, with no limit switches to find the home position on startup, you'd either need to park the carriage in the same place every time you shut down, or else redefine the limits each run.

 

[Pete92]

So if I fit a limit at the back end of the travel of both axis this would do for homing in each time?

 

[techonehundred]

That motor will need a 70 amp brushless motor controller, and then I saw this.



http://logicnc.com/rcnc.html

Look at it and see what you think.

 

[Pete92]

I like the look of that, looks just to need a ESC to go with it. I am looking at this sort of thing: http://www.ebay.co.uk/itm/Castle-Ph...586?pt=LH_DefaultDomain_3&hash=item3cf65faee2

Where would I connect the 24V PSU in this circuit?

 

[techonehundred]

You would attach the power to the red/black of the ESC. The data for the speed control comes through the parallel to the 3 wire connection. The ESC then takes the data from the Parallel port to regulate how much of the high power goes to the motor and sends through the 3 wires to control motor power and speed.

I think this is what you are asking.

 

[Pete92]

Does anyone know if Logicnc are still trading?

 

[ruzzie]

I got this reply from Logicnc today

Unfortunately, I have discontinued these due to lack of demand,
since most people are switching to USB compatible driver boards
which have this built in ... I just haven't got around to
updating the website.

I can however offer you a limited solution if you are using Mach3:


If you set up Mach3 for PWM spindle control at 50 Hz and then set
Mach3 to 10-20% of maximum rpm you can use this signal to control
a standard hobby ESC (Electronic Speed Control). For example if
you have Mach3 configured for a 10000 rpm spindle you will be able
to vary your brushless motor from 0 to 100% rpm (typically you may
not be able to start a standard hobby brushless motor until you
are about 40% though) by commanding Mach3 to set an rpm of between
1000 and 2000. In this case setting Mach3 to 1000 rpm will
actually command your motor to 0 rpm and setting Mach3 to 2000 rpm
will command your motor to 100%...you can vary motor rpm by using
any number between 1000 and 2000, but as far as I know there is no
way to get the Mach3 rpm to match your actual motor rpm when doing
it this way.

 

[Pete92]

I got the same reply. Well its back to the drawing board

 

[ninefinger]

Why do you need to replace the original Emco motor and control? The power supply for it is right there with the machine so it being an odd voltage should not matter. The speed control for it has a potentiometer input that can be accessed easily along with the spindle on/off switch. Would be much cheaper to interface to these points than replace the motor, power supply and drive.

Just my 2 cents,

Mike

 

[mu38&Bg#]

The RC ESC is less than ideal. I use one in my brushless mill spindle, but essentially as an on/off control with LinuxCNC. It doesn't need any extra hardware at all. I'm not certain that there is enough resolution in the signal to control RPM over a wide range. Most ESC have 256 steps and some have self adjusting input signal. If you add hall sensors to the motor you can use an industrial drive like http://www.ebay.com/itm/Advanced-Mo...055?pt=LH_DefaultDomain_0&hash=item2edbe8e987 Adding sensors isn't difficult. http://www.linushelgesson.se/2012/04/modifying-the-turnigy-80-100-brushless-outrunner-part-2/

I know you're deep into this conversion, but there was an article about converting the Compact 5 to Mach control with no modifications to the lathe electronics at all. Digital Machinist Summer 2007. I think you can find the article online.

Greg

 

[Rex]

An addendum to an older thread:

The Digital Machinist article referenced above. applied to the Compact 5 PC, and would not apply to the Compact 5 CNC. Since the OP referenced a Mk1 model. I would assume his is the CNC variant.
I am in the process of converting a Compact 5 CNC. I did quite a bit of research before determining that the best course was to sell the original control unit en toto and start with new stepper and drivers.

I, like the OP, am in need of a spindle motor. Rather than buy a used Emco motor off ebay, I would prefer a more stnadard DC motor, or even a 3-phase if I can find one to fit the available space. Frankly a hobby RC motor would never have occured to me. Is this a realistic possibility?
Any more thoughts on this?

The idea of using servo drives for the spindle motor is something I had not thought of. Is a servo going to behave just like any PM DC motor? Are the encoders of any use in such an application?

 

[willburrrr2003]

If your original motor is controlled by a speed pot on the unit, you can wire in a c6 speed controller board. It takes a frequency from your cnc software and turns it to a 1-10v output voltage (to the wires that were connected to the speed pot, you measure voltage across the pot and set the output of the c6 to be no more than the voltage you measure). It is made to work with Mach3, but works with linuxcnc as well. If you want to know more about controlling your spindle this way, let me know and I will help all I can.

Regards,

Will

 

[xpylonracer]

Hi Rex

Have you considered a PM motor from a treadmill ?
They are available in 180v and rpm from 4000-5500 with power ratings to 2HP, far more than required but always good to have high torque at low speeds.
Speed controls could be from the same source as the motor or KB do a vast range at low cost.

Emgee