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Author Topic: Help with spindle speed control for Mini Lathe  (Read 11418 times)

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Help with spindle speed control for Mini Lathe
« on: April 25, 2009, 07:06:10 PM »
I am looking for advice on what hardware and wiring needed  to begin to use spindle speed control on my converted  CNC Mini Lathe.  What boards can anyone suggest, and if you could point me in the direction to find out how to wire the lathe, it does have a variable speed control knob on it.

Thanks for any help you can give.

Tom
Re: Help with spindle speed control for Mini Lathe
« Reply #1 on: April 25, 2009, 11:36:34 PM »
Hi Tom,

I just got my Taig microlathe fully converted.  For motor control I am using a C6 Step/Dir conversion as a potentiometer replacement.  The DC output and ground from the C6 provides input in place of two legs of the pot.  I also used a C3 board with optical sensor to close the loop.  Both boards acquired from cnc4pc.com.

The C6 requires a 12V power supply and the C3 a 5V supply.  Grounds should be case isolated.

Hope this helps,   Joe
« Last Edit: April 25, 2009, 11:46:04 PM by jtheath »
Re: Help with spindle speed control for Mini Lathe
« Reply #2 on: April 26, 2009, 12:38:37 AM »
I am looking for advice on what hardware and wiring needed  to begin to use spindle speed control on my converted  CNC Mini Lathe.  What boards can anyone suggest, and if you could point me in the direction to find out how to wire the lathe, it does have a variable speed control knob on it.

Thanks for any help you can give.

Tom

Hi Tom,

HAve a look at the DigiSpeed range of Speed controllers I make and sell.  The DC-06 uses step and dir control sognals. The DC-03 and DC-02 use PWM. They all have an option for an on-board DC/DC converter so that an additional isolated 12V supply is not needed.

http://homanndesigns.com/store/index.php?main_page=index&cPath=1

I use a DC-02 on my Taig mill and 7x14 lathe as it has an option for an onboard  potentiometer so it can be used in a manual mode when required as well.


Cheers,


Peter.
----------------------------------------------------
Homann Designs
http://www.homanndesigns.com
email: peter at homanndesigns.com

Offline simpson36

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Re: Help with spindle speed control for Mini Lathe
« Reply #3 on: April 26, 2009, 03:11:21 AM »
I've had trouble with a couple different boards and recently tried out Homann Design's new stuff.

The new PWM version puts out a rock steady control votage from Mach3, something I was unable to get with the other boards. I finally have a nice steady Mach3 controlled spindle speed on my X2. HIGHLY recommended.

CAUTION CAUTION CAUTION!!!   Make absolutely sure to use an ISOLATED speed controller. If you connect non-isolated speed controllers to the variable speed controls in these import machine tools, you get a pop and expensive smoke.

That goes for replacement variable speed drives also like those from Minarik and KB. I fried two Minarik controllers connecting them to CNC4PC boards. And that takes out a lot of other stuff with it when if goes. That is the expensive way to learn about 'isolation'.

Suggestion: leave yourself a way to switch back to manual control while a program is runing. Sometimes you may need to vary the speed during a cut to clear up chattering, etc.



« Last Edit: April 26, 2009, 03:14:17 AM by simpson36 »

Offline Hood

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Re: Help with spindle speed control for Mini Lathe
« Reply #4 on: April 26, 2009, 03:33:03 AM »
Suggestion: leave yourself a way to switch back to manual control while a program is runing. Sometimes you may need to vary the speed during a cut to clear up chattering, etc.
Not just use SRO or FRO in these situations?
Hood

Offline simpson36

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Re: Help with spindle speed control for Mini Lathe
« Reply #5 on: April 26, 2009, 04:04:50 AM »
Hood,

I have not had success changing speed in Mach once a program is running. I have not tried in a while as I gave up getting my spindle to work with Mach until recently when Homann came out with a new board that works beautifully. So this is goint to be a priority again.


What is the correct proceedure to change spindle speed while a program is running?

Offline Hood

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Re: Help with spindle speed control for Mini Lathe
« Reply #6 on: April 26, 2009, 04:08:51 AM »
Does the slider not change that for you?
Hood

Offline simpson36

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Re: Help with spindle speed control for Mini Lathe
« Reply #7 on: April 26, 2009, 08:51:15 AM »
If you are referring to the up and down buttons in the Spindle Speed panel on the program run page, then no they did not have any effect for me but then that was several versions ago and I was having trouble with the whole speed control issue anyway. The spindle speed wavered all over the place, and it was anyone's guess what programmed changes were going to do.

I'll give it a try again now that I have the speed comtrol working. It sure would be handy to manually tweak the speed (and/or feedrate) of a running program..

Right now I'm down waiting for a new power supply, so I'll post back when I'm running again.

Thanks for the help!
Re: Help with spindle speed control for Mini Lathe
« Reply #8 on: April 26, 2009, 10:42:58 AM »
Thanks for the input. I think I will try the Homann board, and see if I can figure out how to make that work.

Tom
Re: Help with spindle speed control for Mini Lathe
« Reply #9 on: April 26, 2009, 11:59:52 AM »
Peter,
 I was just looking at your website. I think that the DC-02 is the way that I want to go.  Can you tell me what options would be best for me, the lathe that I have is a Clarke 7x12 Mini lathe. I used the the Ron Steele CNC conversion Instructions and ordered the recommended proximity sensor from Euro Spec #is12-y4-n-oc. I just want to be sure that I will not run into any problems with the wiring. Also I plan on using the Smooth Stepper, will that be any problem?

I also think that I want to use the existing manual speed contron knob, and the dc-dc converter, also the led not on the board.  What do you think would be best, you know allot more than me.

Thanks,
Tom