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Mach 3 lathe with stepper spindle
« on: January 26, 2017, 07:02:45 PM »
Can mach 3 lathe drive a stepper motor continuously as a spindle?

Offline JDG3

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Re: Mach 3 lathe with stepper spindle
« Reply #1 on: January 27, 2017, 08:54:08 AM »
I dont see why not. It can control four axis, and you have Acceleration and velocity settings. I think you could translate feed to speed with a tach.
20 IPM = ?RPMS
Not sure how the program would be written G0 A(axis) to infinity until stop.
I dont know if it can be run under the spindle settings tho. That would be cool.
« Last Edit: January 27, 2017, 08:56:51 AM by JDG3 »

Offline RICH

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Re: Mach 3 lathe with stepper spindle
« Reply #2 on: January 27, 2017, 09:13:34 AM »
Gary,

Not sure what your up to........

A stepper used to continuously rotate the lathes spindle will be restrictive in use.
Maybe if tuned and used at some specific point on the motor curve if will satisfy a need.
Just not  a good application of a stepper.

Mach has no ability to spin an axis continuously if configured as a rotary axis.

RICH







Offline JDG3

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Re: Mach 3 lathe with stepper spindle
« Reply #3 on: January 27, 2017, 09:27:52 AM »
I dont see why not. It can control four axis, and you have Acceleration and velocity settings. I think you could translate feed to speed with a tach.
20 IPM = ?RPMS
Not sure how the program would be written G9999 F- A(axis) to infinity until stop.
I dont know if it can be run under the spindle settings tho. That would be cool.
Yeah this wouldnt work. I dont think the other axis would move, waiting for it to catch up.
Re: Mach 3 lathe with stepper spindle
« Reply #4 on: January 27, 2017, 10:55:15 AM »
The deal is this. You've probably seen Tormach's Duality Lathe.  I have a similar set up except my home built CNC machine is constructed like a horizontal boring mill (HBM) with a table that does not move.  The spindle though can be oriented as in a horizontal mill or a vertical mill. 
So I have a stripped down Harbor Freight 7 x 12 lathe  with just a headstock and tailstock that mounts to the table.  A Tormach 0XA toolpost is mounted behind the milling spindle for lathe work.  I have a large stepper driving the lathe spindle through a 8mm x 30mm timing belt with a 3 to one reduction.  So this makes a pretty nice fourth axis.  However my experiments indicate I can easily spin the lathe at better than 500 rpm, and the driver I used for the stepper can actually handle a really big stepper if I want.

So what I am trying to figure out is did I miss that the Lathe version of Mach 3 can drive a stepper spindle where the Mill version cannot.  If it can't I have finally come up with a plan B. I found a little board that will accept PWM input and output pulses to drive a stepper at a continuous speed.  My machine has a Xuilifeng 4 axis motion card that has the PWM spindle too.  So then mach 3 will run the spindle as if it is an ordinary spindle motor.

Offline RICH

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Re: Mach 3 lathe with stepper spindle
« Reply #5 on: January 29, 2017, 08:39:59 AM »
GARY,

The Mach3 mill screen can be used to run the lathe if you rename the screen set to a ".lset" so Mach knows it's a lathe. What are the specifics internaly .....I don't know!

The only thing I did "long time ago" was  to use a stepper motor geared downto turn the lathe spindle and it was configured as a rotary and slaved to the Z axis. I also used it to index the spindle but was using live tooling on the carriage for milling and drilling. Intended purpose was for small stuff so one need not remount the piece from the lathe to a milling machine. Was able to do  neat stuff but it was limited.

I am not up on Tormach's stuff but The Duality Lathe can not be used with Mach3 and needs Tormach's program.

Simpson did a development on using the Mill spindle to do the equivilant of what you see in the Tormach videos. He uses "swap axis" function but note that swap axis only changes the pin outs,thus, if what your swawping is not the same it won't work and he also learned  that a stepper was not good for what he wanted to do.

Save some time and have a look at Simpson's site for what he now does:
www.theInTurn.com
http://www.theinturn.com/


Info on some of Simpson's Macro's.
http://www.machsupport.com/forum/index.php/topic,11422.msg96092.html#msg96092

Here is a link to a board created by Simpson so the swap axis is done via hardware and also macro's posted
http://www.machsupport.com/forum/index.php/topic,11422.msg99637.html#msg99637

Not sure I can be of much more help,

RICH