Author Topic: Stepper motor power feed for RF45 milling machine  (Read 404 times)

Offline JCvdW

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Stepper motor power feed for RF45 milling machine
« on: April 27, 2021, 05:23:09 PM »
I am currently busy building the MEM Corliss Steam Engine. https://www.modelenginemaker.com/index.php?topic=10004.new#new

I tried to fly cut some of the parts on my RF45 milling machine clone and struggled to obtain a good surface finish. What a good excuse to build an X-axis power feed for the milling machine!

What follows is not a detailed build log, but mostly photos to show the general idea.

Basic requirements for the power-feed were:

1. Variable speed setting with digital indication of speed, to allow repeatability.
2. Three way toggle switch to move in either direction, or stop the table and disable stepper motor driver.
2. Push button initiated rapid feed, to quickly move the table.
3. No end stops - to keep me awake while using the power feed.
4. Drive mechanism must not protrude above the table surface.
5. All electronics and mechanics protected from swarf.
6. Retain use of both manual feed wheels.

I already had a 2A Nema 23 stepper motor, a stepper motor driver and a 24V DC power supply. I decided to use this, as a more powerful motor can always be installed later if needed.

General approach:

1. Use an Ardunio Uno as controller.
2. Connect the stepper motor to the X-axis lead screw with a timing belt, with a 1:2 pulley ratio.
 
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Offline JCvdW

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Re: Stepper motor power feed for RF45 milling machine
« Reply #1 on: April 27, 2021, 05:36:01 PM »
First step was to determine how to control the speed of the stepper motor with the Ardunio Uno using a potentiometer as input. I found that using the Ardunio tone() function to generate a square wave works best. The frequency of the square wave can be set according to the voltage from the potentiometer.

First setup on the bench:


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Offline JCvdW

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Re: Stepper motor power feed for RF45 milling machine
« Reply #2 on: April 27, 2021, 05:45:42 PM »
I removed the dial ring on the end of the X-axis lead screw to mount the timing pulley in its place.



I then bored the timing pulley for a snug fit, and Loctite it in place.




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Offline JCvdW

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Re: Stepper motor power feed for RF45 milling machine
« Reply #3 on: April 27, 2021, 06:05:00 PM »
The controls consist of:

1.  A three way toggle switch to: feed left, off, and feed right
2. A push button to override the speed setting and rapidly move the table
3. A potentiometer to set the speed.

The controls were mounted on the side of the plastic box that houses the Ardunio Uno. Included in the box is a small DC to DC converter to convert from 24V to 5V required by the Uno.



First action:


« Last Edit: April 27, 2021, 06:50:41 PM by JCvdW »
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Offline Admiral_dk

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Re: Stepper motor power feed for RF45 milling machine
« Reply #4 on: April 27, 2021, 06:44:55 PM »
Interesting project - but no video - error message
Quote
#Invalid YouTube Link#

I'm not sure - but have you enabled / made the YouTube file Public ?

Per

Offline JCvdW

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Re: Stepper motor power feed for RF45 milling machine
« Reply #5 on: April 27, 2021, 06:52:31 PM »
Interesting project - but no video - error message
Quote
#Invalid YouTube Link#

I'm not sure - but have you enabled / made the YouTube file Public ?

Per

Thanks Per, it seems to work now...
« Last Edit: April 27, 2021, 08:16:12 PM by JCvdW »
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Offline JCvdW

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Re: Stepper motor power feed for RF45 milling machine
« Reply #6 on: April 27, 2021, 06:58:31 PM »
With the basics working, I decided that a display is needed to at least indicate speed between 0 and 100%.

First test with a four element seven segment LCD display, before mounting it.



The control box in its final position next to the mill, with the LCD display mounted.


« Last Edit: April 27, 2021, 07:01:36 PM by JCvdW »
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Offline JCvdW

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Re: Stepper motor power feed for RF45 milling machine
« Reply #7 on: April 27, 2021, 07:09:44 PM »
To mount the stepper motor and timing pulleys, a box was made from 6mm aluminium plate.







« Last Edit: April 27, 2021, 08:17:09 PM by JCvdW »
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Offline JCvdW

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Re: Stepper motor power feed for RF45 milling machine
« Reply #8 on: April 27, 2021, 07:25:05 PM »
And finally, the power feed in action to fly cut the mild steel cylinder block of the MEM Corliss steam engine. The stepper motor driver and DC power supply are mounted out of harms way underneath the plywood base.


Very happy with the result:


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Offline EricB

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Re: Stepper motor power feed for RF45 milling machine
« Reply #9 on: April 27, 2021, 08:18:39 PM »
Great idea! Thanks for sharing.

Eric

Offline propforward

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Re: Stepper motor power feed for RF45 milling machine
« Reply #10 on: May 04, 2021, 02:26:36 AM »
That is a great approach and result - nice and compact. The results speak for themselves.
Stuart