little machine shop 7 x 16 lathe conversion

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martyscncgarage
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Re: little machine shop 7 x 16 lathe conversion

Post by martyscncgarage »

Probably need the manual for the spindle drive.
If you search this forum for Brushless spindle motor you will get some hits.
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LMSCNC
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Re: little machine shop 7 x 16 lathe conversion

Post by LMSCNC »

Hi Marty,

It looks like I can buy a KBSI-240D card to be able to control the spindle motor. I should also be able to use the relay board that came with the Acorn board for use of forward and reverse. Someone please correct me if I am wrong.

Thanks
Dave
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Re: little machine shop 7 x 16 lathe conversion

Post by martyscncgarage »

LMSCNC wrote: Mon Apr 26, 2021 9:53 am Hi Marty,

It looks like I can buy a KBSI-240D card to be able to control the spindle motor. I should also be able to use the relay board that came with the Acorn board for use of forward and reverse. Someone please correct me if I am wrong.

Thanks
Dave
Hi Dave,
I believe several users have used the KBSI-240D. It is a signal isolator. I personally have not.
Yes, you can use the relay board in lieu of the switches.

Marty
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Re: little machine shop 7 x 16 lathe conversion

Post by LMSCNC »

Hello all,

Well after ordering KBSI-240D card I found a card that LMS sells that is made just for my lathe.

Image

This CNC spindle control kit consists of a small circuit board that replaces the circuit board with the speed control potentiometer, plus a replacement chip for the motor controller card.
This conversion kit works on many SIEG SX2 and HiTorque mini mill as well as SIEG SC2 and HiTorque mini lathes.

So it looks like i will be sending the KBSI-240D card back

~Dave
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Re: little machine shop 7 x 16 lathe conversion

Post by martyscncgarage »

LMSCNC wrote: Mon May 03, 2021 10:23 am Hello all,

Well after ordering KBSI-240D card I found a card that LMS sells that is made just for my lathe.

Image

This CNC spindle control kit consists of a small circuit board that replaces the circuit board with the speed control potentiometer, plus a replacement chip for the motor controller card.
This conversion kit works on many SIEG SX2 and HiTorque mini mill as well as SIEG SC2 and HiTorque mini lathes.

So it looks like i will be sending the KBSI-240D card back

~Dave
Cool. Post the documentation for the LMS card so we can see what it says.
Reminder, for support please follow this post: viewtopic.php?f=20&t=383
We can't "SEE" what you see...
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Re: little machine shop 7 x 16 lathe conversion

Post by LMSCNC »

Hi Marty,

here is a link to the card on their website. i was not able to post the file here for some reason.


https://protect-eu.mimecast.com/s/7abNC ... lmscnc.com

~Dave
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Re: little machine shop 7 x 16 lathe conversion

Post by martyscncgarage »

You should call and verify that it provides signal isolation for the 0-10vdc analog input.
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Re: little machine shop 7 x 16 lathe conversion

Post by LMSCNC »

Hi Marty,

Here are some replies from LMS..

"I have no idea, but what is your concern? You will have a common ground."

"The 0-10V signal is coming FROM your Centroid Acorn Board. How would isolation work?"

I am not sure what to say back to him as I am kind of lost myself.

would i still need to use the KBSI-240D card?

Thanks for any help with this.

~Dave
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Re: little machine shop 7 x 16 lathe conversion

Post by Richards »

Signal isolation can cause problems. Let's take a simple example. Most stepper drivers and servo drives completely isolate incoming pulse and direction signals from the actual drive circuitry. Opto-couplers make that isolation possible. The device sending the signal turns on an LED inside the opto-coupler. The device receiving the signal detects the LED's light. There is no physical connection between the two devices except a beam of light.

Setting a motor's rotational speed can be done by sending a 0-10V analog signal where 0=OFF, 5V=half speed, and 10V=full speed. Other voltages cause the motor to run at a speed proportional to the voltage of the analog signal. In other systems, instead of using an analog signal, a digital signal is used where the width of the pulses during a certain amount of time determine the motors speed. That system uses PWM (Pulse Width Modulation) signals. There are lots of examples on the Internet that explain the basics of Pulse Width Modulation.

When the two systems are mixed without the proper interface, bad things happen. Some people think that by having a common GROUND between the systems, that nothing bad will happen. That's not always the case. Two separate devices with a common ground can still fry each other. It's best to think of the two devices as two Black Boxes where the contents of the boxes are unknown. A Black Box device can talk to another Black Box device without knowing what's inside of either Black Box if someone who does know what's inside has provided an interface between the Black Boxes. The interface that Marty recommended is that kind of device. There may be other interfaces available. It really depends on EXACTLY what your motor driver needs and EXACTLY what the Acorn provides.

This post is meant to show that interfacing a DC spindle motor CAN be the most difficult part and confusing part of designing a CNC controller. If the proper interface exists, then it's plug and play. If no interface exists, then it can be a big problem.

If the motor that you have is out of production, you might consider replacing it with a new motor/driver combination that is plug and play with the Acorn. Spindle motors that run as high as 40,000 are available for CNC machines. Some are affordable. Others costs many thousands of dollars. Some are designed to run best with a narrow range of RPMs. Others have constant torque over a wide range of speeds.

When I added a spindle to my Shopbot router many years ago, I never interfaced the motor's speed to the Shopbot controller. The Shopbot controller turned the spindle on and off, but I manually controlled the spindle's speed through its keypad. The same thing can be done with almost any motor by using an Acorn output relay to turn the motor on or off. It's not as convenient as having the Acorn control the speed, but its easy do. If a Solid State Relay is used instead of just the mechanical relay on the Acorn, even better electrical isolation is possible.

EDITED:
I was following two different threads and got things mixed up in my mind. Please disregard anything in my post that is not pertinent to this thread.
-Mike
-Mike Richards
LMSCNC
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Re: little machine shop 7 x 16 lathe conversion

Post by LMSCNC »

Thanks Mike,

I will send this info to LMS and hopefully get a answer on the card I just bought from them.

~Dave
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