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### Author Topic: Servo for lathe spindle ?  (Read 22554 times)

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#### tasbiz

• 57
##### Re: Servo for lathe spindle ?
« Reply #60 on: October 03, 2014, 10:30:45 PM »
The wires on the drive are connected +10V to V-ref and -10V to GND (Nr 20 and 19 respectively)

Tasbiz

#### tasbiz

• 57
##### Re: Servo for lathe spindle ?
« Reply #61 on: October 03, 2014, 11:03:00 PM »
I attach some pictures of wiring

Tasbiz

PS: I am also giving you a link(i hope i am not asking for too much) to Delta's download of the manual of the drives...

#### Hood

• 25,838
• Carnoustie, Scotland
##### Re: Servo for lathe spindle ?
« Reply #62 on: October 04, 2014, 07:07:47 AM »
Ok I would suggest you have the drives RPM and the Velocity set in Mach to equal one another, that however does not mean the same numbers as one is RPM and the other axis Velocity.

The reason I suggest that is because you are using a +/-10  voltage to define the Velocity and if the drive thinks 10v = 3000rpm but the CSMIO thinks 10v is something else then you may be running into difficulty.

Ok so if 10v = 3000rpm in your drive then the velocity in Mach you want is -

3000 rpm of motor  x 0.8 reduction =  2400 rpm on ballscrew
Velocity = 2400 rpm of ballscrew x 5mm pitch of the screw = 12,000mm/min

Another thing to note is you need the correct Steps per Unit set for each axis, I think you have a 2500 line encoder so that would mean your actual count as far as Mach is concerned is 2,500 x 4 = 10,000 counts per rev.
Now your reduction comes into play here so for 1 rev of the ballscrew that would be 10,000 x 0.8 = 8,000, this however is per ballscrew revolution, so your steps per unit (mm in your case) would be 8,000/5 =  1,600, so  your steps per unit in Mach would be 1,600.

Regarding Sinking and Sourcing.

If an Input is Sinking it means you have voltage going into the input and the drive sinks it to Gnd/com-/0v
If and Input is Sourcing it means voltage is coming out of the Input and your connected device sinks it to Gnd/com-/0v

Same idea for outputs.

I will have a look at the manual later today to see if the Inputs can be configured sink or source as often they can be.

Note the Sink/Source I am talking about is for the digital I/O of your drive and not the analogue or encoder I/O, you have no problems with these.

I also forgot to respond to an earlier point where I said I also had the Gnd of CSMIO connected to the Encoder Gnd of my drives. My drives have that possibility but it looks like yours do not. It is not required but as mine have that I prefer to connect it.

Hood

#### tasbiz

• 57
##### Re: Servo for lathe spindle ?
« Reply #63 on: October 04, 2014, 08:09:26 AM »
Thank you Hood,
I will do as you say.
I have a suspicion.When you look into the manual please see.It looks to me that by default the drive comes with 3 integral speeds saved i.e. 1000 2000 and 3000 rpm.To use an external analogue 0-10V signal for speed I think i have to disable those.Something is mentioned in the manual but i am not sure how to do it.That however makes sense to me- as i jog if the voltage rises further than a certain point in the input of the drive the drive switches to integral speed no2 or even 3- and that explains perhaps the sudden increases in speed while i jog.Could i be right?

Tasbiz

#### tasbiz

• 57
##### Re: Servo for lathe spindle ?
« Reply #64 on: October 04, 2014, 12:25:50 PM »
I found a quick start guide for setting up the drives
I attach it.It is very short...

Tasbiz

#### tasbiz

• 57
##### Re: Servo for lathe spindle ?
« Reply #65 on: October 04, 2014, 01:14:40 PM »
Do you think i would go beter if i was using CSMIO-S instead of analogue?

Tasbiz

#### Hood

• 25,838
• Carnoustie, Scotland
##### Re: Servo for lathe spindle ?
« Reply #66 on: October 04, 2014, 06:34:51 PM »
The IP-S would undoubtedly be easier to set up but when you get the IP-A set up you will be happy you went that route as it has benefits. One example is that you only have to reference the machine once at start up of Mach and you can be sure that the axes are exactly where Mach thinks they are until you shut Mach down again. The reason for that is the encoders are constantly monitored even when the drives are disabled (assuming the logic side of the drive is still live) , so even moving the axis by hand Mach will know where they are. Similarly if you hit a limit or even E-Stop the machine, Mach still knows exactly where it is as the position is updated from the encoders.
With the IP-S you really need to re-reference each time you take Mach out of reset as the axes could have moved slightly after being disabled and again when enabling.

Ok had a quick look at the manual, P1-40 seems to be where you set the speed to correspond to 10v, I think that will be set to the rated speed of your motor by default and that is what you really want unless you think the rapid is too fast at that. If you wish to set a slower rapid in Mach (Velocity entry) then work out what motor RPM would be needed for that Velocity and set that up in the drive.
In your case that would be done by Velocity divided by 5(pitch of ballscrew) then that value divided by 0.8 ( reduction)

Regarding the Speed mode, this is my understanding from a quick read.
You have a choice of External and Internal speed commands, you want external as you will be controlling from the +/- 10v output from the IP-A.
If you have SPD0 and SPD1 unconnected then that will put the drive into S1 mode which is external speed control.

Hood

#### tasbiz

• 57
##### Re: Servo for lathe spindle ?
« Reply #67 on: October 05, 2014, 05:13:11 AM »
Hi Hood ,
I have tried switching the motor to torque mode and retune...
With Speed mode thinks are very immediate for me...
After fiddling around and ofcourse setting P1 40 to a lower setting (1750 RPM),
I thing that i need to change my gear ratio from 0.8 to 0.5 or lower (change the ballscrew gear to bigger one).That way the speed of the motor can be as high as 3000 rpm but the rapids are going to be lower.
Do you agree i should do that?

Tasbiz

#### tasbiz

• 57
##### Re: Servo for lathe spindle ?
« Reply #68 on: October 05, 2014, 12:39:12 PM »
No success!!
I have switched the servo back to Speed mode.It looks like it works better in that mode than in any other that i have tried...
The csmio doesnot put a kd value in autotune mode.Should i try and put something myself?

Tasbiz

#### Hood

• 25,838
• Carnoustie, Scotland
##### Re: Servo for lathe spindle ?
« Reply #69 on: October 05, 2014, 02:41:00 PM »
Ok so what is happening now that you have lowered the RPM in the servo drive to 1750rpm and have it in Speed mode?
Do you have Velocity in Mach set to 7000?

You could decrease the ratio but it would give you less torque and I do not think it will help you any.

Yes, auto tuning in the CSMIO likely wont get you perfect results, I used it to get me some numbers then just messed about from there. What I did was just set it up in the plugins tuning page to move back and forth and adjusted the settings one at a time, increasing or decreasing just one of them until I got the best error then moved on to the next setting and doing the same.

Hood