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DC Motor as Rotational axis
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Topic: DC Motor as Rotational axis (Read 5406 times)
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jr_82
29
DC Motor as Rotational axis
«
on:
March 28, 2011, 12:21:41 AM »
I have a DC motor that I would like to run as a 4th axis Rotational. This is not for speed. It is to rotate stock. It has a gear box with a 660 to 1 ratio. nice and slow. How do I get Mach to run it as an axis? the motor has 3 wires one for each direction of movement and another that does nothing. I assume it is another ground of some sort.
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Junior
Tweakie.CNC
9,199
Super Kitty
Re: DC Motor as Rotational axis
«
Reply #1 on:
March 28, 2011, 03:53:28 AM »
Hi JR,
I know nothing of lathes but the rotating headstock is fitted with a slotted disk which interrupts the beam from an optical sensor. This pulse is then fed into Mach to measure RPM and is used for synchronizing threading etc. A similar system is used for spindle speed control on a mill.
You may need to do a bit of searching but there are details of spindle setups on the forum.
Tweakie.
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PEACE
Hood
25,835
Carnoustie, Scotland
Re: DC Motor as Rotational axis
«
Reply #2 on:
March 28, 2011, 06:10:54 AM »
To run it as an axis you will need to have control over it with a servo drive, that will require you have an encoder on it as well.
If simply wanting to use it as a spindle, ie no sync between other axis then a relay would likely be all you need to operate it via Mach.
Hood
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jr_82
29
Re: DC Motor as Rotational axis
«
Reply #3 on:
March 28, 2011, 09:06:25 AM »
Like the relay that is on my board, that just turns on and off a spindle?
JR
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Junior
jr_82
29
Re: DC Motor as Rotational axis
«
Reply #4 on:
March 28, 2011, 09:08:37 AM »
I still need it to move to certain positions ie, 0 180 90 270 degree, will I have a reading in the dro? for the angle.
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Junior
Hood
25,835
Carnoustie, Scotland
Re: DC Motor as Rotational axis
«
Reply #5 on:
March 28, 2011, 09:49:24 AM »
If you need to use it as a true axis then you will need to add an encoder and get a suitable drive to control direction and speed.
Hood
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jr_82
29
Re: DC Motor as Rotational axis
«
Reply #6 on:
March 28, 2011, 10:43:19 AM »
with a relay can I tell it how far to move.
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Junior
Hood
25,835
Carnoustie, Scotland
Re: DC Motor as Rotational axis
«
Reply #7 on:
March 28, 2011, 10:49:02 AM »
No, the relay was mentioned just because you said "one for each direction of movement" about the two wires. So I was thinking if you had a double pole double throw relay you could reverse the direction. You would not have any control over it except you could vary the supply voltage to control the speed and reverse the direction.
For positioning as you would such as with an axis you would need proper control over it by turning the DC motor into basically a servo and that is where the encoder and drive would be required.
Hood
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jr_82
29
Re: DC Motor as Rotational axis
«
Reply #8 on:
March 28, 2011, 11:37:34 AM »
OK thanks!
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Junior
rrc1962
673
Re: DC Motor as Rotational axis
«
Reply #9 on:
March 28, 2011, 11:14:21 PM »
If you need infinite positioning, then you need a motor controller. If you just need 0, 90, 180 and 270 degrees, you can use 4 limit switches. Turn on the motor with a relay and watch for the correct switch to trip.
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