Messages

1

General Mach Discussion / Re: AC servomotor calibration problem

« on: September 03, 2017, 03:21:09 PM »

  yeah i am sitting here with a big smile, yup i am learning and you are right it gets meaning less, but i got caught up in this and just want it to be perfect in case the noise issue in stepmode continues. Yes hobby it is and great when it becomes a succes.

you asked why i didn´t want all that grunt. The anser is my jaw chuck is screwed on the spindle and there is no lock so if the spindle stops in an instant the jaw chuck continues and result is a chuck running over the floor.

I read this manual like 15 times but much is just going right thru without any understanding until you point me in the right direction and explains were, what and how. Then things starts to be understood.

Thanks Craig and now i think i have to let you rest before you give up on me haha. I will play a little tomorrow with what you just told me and then wait for the board. I´ll be back with info on how everything went.

2

General Mach Discussion / Re: AC servomotor calibration problem

« on: September 03, 2017, 02:51:54 PM »

Hi,
when you disable the servo it stops at its max acceleration. You can set that....although why you would set it less than its capable of...you have
paid for all that luvly grunt and now you don't want it?

The offset must be perfect if you expect it to stop. In your lathe you will use the disable pin under Machs control to stop.

I think you can program the brake so that it doesn't come on when the drive is disabled. When disabled you should be able to jog, when enabled
it is in primary control mode and it ignores jog which is its secondary control mode as per previous post.

Craig

somewere in the manual it says that jog is only available in step and position mode. so i think i have to use the software to go back to syepmode before jog is an option again. I haven't seen any program option in the software were i can do anything to either brake or toeque. Torque can only be worked with if i choose analog torgue instead of analog speed.
If you do not have a solution i guess i have to overcome this with a switch on the power cord to the brake and then put it in stopmode so the torque is 0.

3

General Mach Discussion / Re: AC servomotor calibration problem

« on: September 03, 2017, 12:01:08 PM »

Hi,
if you require your spindle to do indexing operations then you need to use position control per section 6 in the manual. 'Position
with Following Error' is the right dynamics mode (sounds and vibes) and on the screen on page 6.3 the right choice is about 4000 pulse
per rev.

If you just want to get your spindle going and make some chips then you use section 7 Drive Control with Analogue Interface. On the screen on
page 7.2 you can set the voltage, offset and speed that you wish. Note that at no time do you need to set the 'pulse per rev' that's required
for position control not speed control.

Just as an aside this servo doesn't have an encoder at all, it has a resolver, a very VERY groovy technique from
analogue days, makes me come over all misty eyed! The pulse per rev setting is actually a programmatic setting for the 'Resolver to Digital' converter
in the drive. Thats how Bosch managed to achieve what is to all intents and purposes a programmable resolution encoder...CLEVER!

Anyway back to analogue speed control....with the settings made per 7.1 and 7.2 all that is now required is to enable the drive and apply a voltage.
To enable the drive (fig 10.56 page 10.54) apply +24VDC to pin 1 X4 with 0V pin 4 X4 and have your BoB or even a short bit of wire apply 24V to pin 3 X4.
Lets for the moment imagine that you selected 10V as max command value and 2000 rpm as max commanded speed. For the moment assume 0V offset.
If you apply 5V between pins 1 and 2 connector X3 per page 7.3 then the servo will run at half speed, ie 1000 rpm. Apply 1V and it will run at 1/10 full speed ie 200 rpm.
The voltage applied could come from PWM from Mach via a low pass filter on your Bob or even easier from a potentiometer hooked to your drive.
Some PWM don't actually quite get to 0V, some hang up about one diode drop above earth at 0.7V. If your PWM is like this use the offset of 700mV
to counteract it. A potentiometer should get to 0V so the offset can be 0mV.

Given how simple having a potentiometer is you should probably have a go just to prove to yourself that you can. On page 7.4 is a circuit diagram of the analogue
input. Note that it says a max of 15V input, DON'T exceed it or will blow it up. Ideally you would get a 10 or 12V regulated DC supply or if you want spindle to go
backwards a -12V, 0V, +12V supply. Why  would you want to go backwards though? You'll need a potentiometer, anywhere between 1 kOhm to 10 kOhm  will be
fine, 10 kOhm is a bit like an arsehole...everyones got one! Hook one of the outside pot terminals to +10V, the other outside terminal to 0V AND pin 1 X3. The centre
pot terminal to pin 2 X3 and the servo should run. If it seems to be going backwards swap the connections between pins 1&2.

Craig

So now it is setup and tested. It works perfect, but then another issue turned up. The jog feature does not work in analog speed mode. This means that when i stop the spindle with enable still active the motor brakes with torque and if i disengage enable switch, then the 24v motorbrake is active,,,darn.
Yet one more issue. When set to spin manually with only a potmeter, the motor stops so hard when start is disabled, that the chuck unscrews and falls off.

It is also very sensitive about the tuning of the offset. i have found my zeropoint at -0.15mv any diffeerence in either way makes the spindle turn either cw or ccw. Quite funny that i can get CCw at full speed just by setting this offset at -10v.
This was a little update and as usual with a few questions as well... Have a greeeat sunday everyone

4

General Mach Discussion / Re: AC servomotor calibration problem

« on: September 03, 2017, 09:30:45 AM »

Hi,
nice of you to say but you haven't met me...easy to be nice over the internet...but you may want to shoot me in real life.

Craig

I can´t find anything about the input terminals construction. Do you know if they are galvanic isolated either with buffer or optocoupler, so i can go direct to the driver without any bob

5

General Mach Discussion / Re: AC servomotor calibration problem

« on: September 03, 2017, 09:10:06 AM »

Hi,
nice of you to say but you haven't met me...easy to be nice over the internet...but you may want to shoot me in real life.

Craig

haha yeah that´s right. It´s just nice to have people who offers their own time to help other. Hope i some day can repay, by helping other who needs my knowledge.

6

General Mach Discussion / Re: AC servomotor calibration problem

« on: September 03, 2017, 07:25:25 AM »

Hi,
if you require your spindle to do indexing operations then you need to use position control per section 6 in the manual. 'Position
with Following Error' is the right dynamics mode (sounds and vibes) and on the screen on page 6.3 the right choice is about 4000 pulse
per rev.

If you just want to get your spindle going and make some chips then you use section 7 Drive Control with Analogue Interface. On the screen on
page 7.2 you can set the voltage, offset and speed that you wish. Note that at no time do you need to set the 'pulse per rev' that's required
for position control not speed control.

Just as an aside this servo doesn't have an encoder at all, it has a resolver, a very VERY groovy technique from
analogue days, makes me come over all misty eyed! The pulse per rev setting is actually a programmatic setting for the 'Resolver to Digital' converter
in the drive. Thats how Bosch managed to achieve what is to all intents and purposes a programmable resolution encoder...CLEVER!

Anyway back to analogue speed control....with the settings made per 7.1 and 7.2 all that is now required is to enable the drive and apply a voltage.
To enable the drive (fig 10.56 page 10.54) apply +24VDC to pin 1 X4 with 0V pin 4 X4 and have your BoB or even a short bit of wire apply 24V to pin 3 X4.
Lets for the moment imagine that you selected 10V as max command value and 2000 rpm as max commanded speed. For the moment assume 0V offset.
If you apply 5V between pins 1 and 2 connector X3 per page 7.3 then the servo will run at half speed, ie 1000 rpm. Apply 1V and it will run at 1/10 full speed ie 200 rpm.
The voltage applied could come from PWM from Mach via a low pass filter on your Bob or even easier from a potentiometer hooked to your drive.
Some PWM don't actually quite get to 0V, some hang up about one diode drop above earth at 0.7V. If your PWM is like this use the offset of 700mV
to counteract it. A potentiometer should get to 0V so the offset can be 0mV.

Given how simple having a potentiometer is you should probably have a go just to prove to yourself that you can. On page 7.4 is a circuit diagram of the analogue
input. Note that it says a max of 15V input, DON'T exceed it or will blow it up. Ideally you would get a 10 or 12V regulated DC supply or if you want spindle to go
backwards a -12V, 0V, +12V supply. Why  would you want to go backwards though? You'll need a potentiometer, anywhere between 1 kOhm to 10 kOhm  will be
fine, 10 kOhm is a bit like an arsehole...everyones got one! Hook one of the outside pot terminals to +10V, the other outside terminal to 0V AND pin 1 X3. The centre
pot terminal to pin 2 X3 and the servo should run. If it seems to be going backwards swap the connections between pins 1&2.

Craig

great Craig
i will go and try it out just for the fun of it. think i will make the final decision when i also have tried the step mode with the smoothstepper.
I can't say this enough. i apriciate your help so much. if all people were like this the world would be a better place..

7

General Mach Discussion / Re: AC servomotor calibration problem

« on: September 03, 2017, 05:39:38 AM »

Hi,
not quite sure yet but yes it would appear that you can program the resolution of the encoder...page 1.4

The number of steps per rotor revolution is adjustable between 16 and
65536.

If that the case then why choose max resolution of 65536? That equates to and angular resolution of 20 arc seconds! If your machine is rigid
and accurate enuf to demand a resolution of 20 arc minute let alone 20 arc second then you should be on a professional forum not a hobbyists one!
Additionally if you think you are going to successfully signal your drive at close to 4MHz your dreaming.

The solution I came up with for my servo driven spindle is:
Program the drive to operate in two different modes, the first, simple velocity mode using analogue voltage and, the second, with step/dir position
control.

Most of my milling ops can be done under plain velocity control, in fact its quite adequate to have just a knob you lean over and twist until the tool is
cutting as you want and the leave it there for the rest of the op...in some cases hours. This is the first of the control stratgegies and is selected by one
digital input (pin4 from memory) being held low by Mach. When I want position control for rigid tapping I go to the other mode by asserting the input
pin high. Typically when I'm tapping I don't tap at 3500 rpm! 100 rpm is fine and consequently the pulse output rate is 13kHz, in fact well within the
pulse rate of a parallel port let alone my ESS. As it turns out ESS can signal 467kHz no probs and my drive can receive 500kHz with differential signalling
but transmitting signals of that frequency can be fun and ultimately not even really useful or required for mill operations.

I haven't read the Bosch manual enuf to know whether it allows this dual mode strategy, my Allen Bradley drive does and I've seen it offered in other
makes as well and guess it is therefore standard fare for modern drives. If it is it would allow you to get simple speed control running and then put
your thinking cap on for the indexing mode. I doubt you will need anything like the max speed of the spindle when indexing and so when you 'gear it
down' (electronically speaking) you don't have to sacrifice resolution hugely and yet still end up with a pulse rate that means you don't have to be an
RF/ High Speed Digital engineer to get it to work.

Craig

Hi again Craig.
I looked in to the solution of driving the servo in analog interface but i am kinda lost, since i am a novice to this. In my manual i can see that via a potmeter to ired 1and 2 i can control torgue or in jogmode velocity and then it says analog signal to e1 and e2. Now it seems you are an expert in this so i hope you have paitience enough to explain to me how i setup this analog mode.

8

General Mach Discussion / Re: AC servomotor calibration problem

« on: September 01, 2017, 08:35:56 PM »

Ok so endgame here is, getting a faster breakoutboard and then play with the setup of velocity vs speed and find a good compromise. I think 2000 rpm is good enough for this little lathe.

As i said it´s not about precision but the sound and vibes. This servo sounds precise as a stepper just louder, but only when i use step mode, so guess the motor is ok.

When i get the smoothstepper i will set it up and then i will return to you with the result and if it´s still wrong, i will take a video so you can see and hear how it acts.
Craig, again thanks a lot..

9

General Mach Discussion / Re: AC servomotor calibration problem

« on: September 01, 2017, 07:32:35 PM »

One more thing, the things you said about pulsrate and not being able to use the 4 MHz made me look for the bob´s spec´s but it says nothing about pulsrates. Do you know how fast those optocouplers are. The board is one of the cheap ones from ebay, called universal mach3 usb parallelport bob. (usb only for voltage supply). I have a pic but i can´t seem to find a way to post it here.

10

General Mach Discussion / Re: AC servomotor calibration problem

« on: September 01, 2017, 07:23:53 PM »

Since i haven´t tried anything in mach3 turn yet, i have to ask.

The ultimate way of cutting on a lathe is to keep the same feed and that means that the speed of the motor have to change all after the diameter of the material your working on, so my question is this, can mach3 control and adjust speed on the spindlemotor in velocity mode, when you attach a potmeter to regulate the speed manually. I am not sure but i think i can only use a potmeter as an override feature in jogmode.

I haven´t read to much about velocity mode in my manual or mach3´s manual, so i have no clue on how to change direction. I only noticed a jog + and - on the driver. Guess i need to study some more and try to see if there is a solution like yours if i can´t get rid of the noise.

You mentioned your milling when talking about your setup. Mine is for a lathe spindle, sorry if i forget to mention that earlier.


Again i bow in respect to you for spending your time on me,, thanks a LOT.


My driver can not do like yours with setting up two different setups, i have to connect to the driver with a old old laptop running win 3.1 or xp (thats how old this software is) and then via software set the driver to work in either analog, velocity, torque or step mode.

The reason for setting the pulsrate this high is to eliminate the noise and vibrations, not for accuracy