Practicality Of Arduino Controlled Precision Power Feed?

shooter123456

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I have been considering an X axis power feed for my mini mill to get cleaner cuts and to speed up the movement of the table. I would like to get a fairly fast jog speed to move the table from one end to the other as with several recent projects I have worn myself out moving the table from one end to another. The machine is an HF X2 clone with 3 axis DRO and belt drive that can get the spindle to about 4000 RPM. I also have a column brace that attaches the column to the base. I was planning to upgrade to a G0704 at the beginning of last month, but I came to realize that there are more than 25 parts I want to make that my machine is capable of but my lathe had more parts I couldn't do than parts I could do. I upgraded the lathe instead and won't have the budget to replace the X2 until next summer.

Picture:
fYOPtkx.jpg

My idea is:

-Directly mount stepper motor to X axis lead screw (16 TPI)
-Wire in switch to cut power to stepper to maintain manual control (as well as E stop)
-Use arduino (not sure which, probably mega) with 4.3" touch screen to control
-Touch screen can control speed, direction, with buttons for jogging with no load
-Keypad to move table precisely once zero'd.

Maybe add a stepper to the Z axis, simply because I find moving the Z axis and locking it precisely to be tedious. A stepper could do it precisely and quickly and could hold it without needing to lock the Z.

I expect to be able to do the X alone for under $100 purchasing:
-Arduino controller
-Compatible driver
-Touch screen
-Stepper
-Power supply
-Stock for mount

The reason I want to go with a stepper and arduino instead of simple DC motor and a voltage controller is because I think with a little extra cost, I can add precision control, more precise feed rates, and options for future upgrades (Full cnc, controllable spindle speed with touch screen, integrate DRO to touch screen).

The programming the arduino isn't an issue for me. I have been a programmer for a few years now and I am pretty good with arduino code.

My questions or calls for advise are:

-What size stepper would I need to move 25 ipm while cutting aluminum with 3/8" end mill with a light cut?
-What size stepper would I need to move simply jog the table 150 ipm under no load?
-Is there an easier/cheaper/less complex way to accomplish the same thing?
-Would it be easier to control the spindle speed using a small stepper on the pot rather than swapping out a board?
-If I were to add a Z axis stepper, is there a way to install it that would negate the need to lock the Z axis when cutting?
 
The current one is $205 and offers speeds of 0 to 12 IPM.

Assuming I can use the parts I have been looking at,

Arduino Mega Board: $8.14
566 oz in Stepper (overkill, likely will go smaller): $38
Arduino compatible stepper driver: $5-10
Power supply: $30
Wiring, mounting hardware, other misc: $10 or so
Total: 96.14 though less since I won't need such a large motor or power supply

So yes, it would come in less than the listed option with hopefully higher speeds, and significantly more controllability.
 
I suggest that if you want to achieve rapid speeds of 150 IPM you might need to use 70 - 80 volt power supply and compatible motor/drive.
 
I suggest that if you want to achieve rapid speeds of 150 IPM you might need to use 70 - 80 volt power supply and compatible motor/drive.
If my math is correct, I need to get the motor to spin 2400 rpm to achieve 150 IPM.

At 200 steps/rotation I need to send 48000 pulses/min. I am having trouble finding data about torque curves and how the number of pulses translates to the necessary voltage/stepper size/power supply/etc.

I realize that 150 IPM might be ambitious, it would take about 3.7 seconds for the motor to move the table the entire X travel of 9.25". 75 IPM would do it in 7.4 which would also be a huge improvement.
 
Here are some realistic charts for various size motor/power supply combinations. Typically you would run the motor in 1/2 step or less mode. I normally run mine at 100:1 (20,000 steps / rev)

https://www.automationdirect.com/static/specs/surestepmotors.pdf
This is exactly what I need! I appreciate that.

With my machine, would there be any benefit to half stepping? 1.8 degrees with a 16 TPI leadscrew would move the table .0003125"/step and I can only measure to .001".
 
Gunrunner you need to order a set of these for the Z axis hand crank. Bill did you just spit coffee on your monitor? :rofl:

View attachment 253356
 


There you go all done for you.


-Is there an easier/cheaper/less complex way to accomplish the same thing?

Like above all done or you could just use a stepper and controller.


-Would it be easier to control the spindle speed using a small stepper on the pot rather than swapping out a board?

Almost all the time you would just use one spindle speed so set it manually


-If I were to add a Z axis stepper, is there a way to install it that would negate the need to lock the Z axis when cutting?

If there was a stepper on Z with power on and not moving the stepper holds the axis still so it is locked when not moving anyway.
 
I would make it all CNC. Then you would have the power feed, readouts and a huge more capability all in the CNC conversion…Dave.
 
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