vector drive permanent magnet motor

[xrayxray]

Just got a price from Omron on the recommended encoder and it is $968.00 dollars....out of my budget.
Sales told me because the encoder is Complimentary Output then that is the reason why the encoder is expensive....so I need to find out if there is a work around so i can use a much less expensive encoder.
Also need to find out what it all means.

Cheers.

[mactec54]

Just got a price from Omron on the recommended encoder and it is $968.00 dollars....out of my budget.
Sales told me because the encoder is Complimentary Output then that is the reason why the encoder is expensive....so I need to find out if there is a work around so i can use a much less expensive encoder.
Also need to find out what it all means.

Cheers.

It will depend on your control software, if it can support a spindle motor encoder for ridged Tapping, for this it synchronizes the motor RPM to the Z axes feed rate, if your control / software can't do this, then you have no use for a Encoder

[xrayxray]

Mactek54,.....Thanks for the Heads up...will look into.....tho at a later date I might be in a position to run software that is suitable...so theres no harm in educating myself about encoders or seeking information...it's not useless info.

Cheers.

[xrayxray]

my intention was to use LinuxCNC....Here's a paste of the document.


6.1. Spindle Synchronized Motion

Spindle feedback is needed by LinuxCNC to perform any spindle coordinated motions like threading and constant surface speed. The StepConf Wizard can perform the connections for you if you select Encoder Phase A and Encoder Index as inputs.

Hardware assumptions:

An encoder is connected to the spindle and puts out 100 pulses per revolution on phase A

The encoder A phase is connected to the parallel port pin 10

The encoder index pulse is connected to the parallel port pin 11

Basic Steps to add the components and configure them: [1] [2] [3]

# add the encoder to HAL and attach it to threads.
loadrt encoder num_chan=1
addf encoder.update-counters base-thread
addf encoder.capture-position servo-thread

# set the HAL encoder to 100 pulses per revolution.
setp encoder.3.position-scale 100

# set the HAL encoder to non-quadrature simple counting using A only.
setp encoder.3.counter-mode true

# connect the HAL encoder outputs to LinuxCNC.
net spindle-position encoder.3.position => motion.spindle-revs
net spindle-velocity encoder.3.velocity => motion.spindle-speed-in
net spindle-index-enable encoder.3.index-enable <=> motion.spindle-index-enable

# connect the HAL encoder inputs to the real encoder.
net spindle-phase-a encoder.3.phase-A <= parport.0.pin-10-in
net spindle-phase-b encoder.3.phase-B
net spindle-index encoder.3.phase-Z <= parport.0.pin-11-in

[mactec54]

my intention was to use LinuxCNC....Here's a paste of the document.


6.1. Spindle Synchronized Motion

Spindle feedback is needed by LinuxCNC to perform any spindle coordinated motions like threading and constant surface speed. The StepConf Wizard can perform the connections for you if you select Encoder Phase A and Encoder Index as inputs.

Hardware assumptions:

An encoder is connected to the spindle and puts out 100 pulses per revolution on phase A

The encoder A phase is connected to the parallel port pin 10

The encoder index pulse is connected to the parallel port pin 11

Basic Steps to add the components and configure them: [1] [2] [3]

# add the encoder to HAL and attach it to threads.
loadrt encoder num_chan=1
addf encoder.update-counters base-thread
addf encoder.capture-position servo-thread

# set the HAL encoder to 100 pulses per revolution.
setp encoder.3.position-scale 100

# set the HAL encoder to non-quadrature simple counting using A only.
setp encoder.3.counter-mode true

# connect the HAL encoder outputs to LinuxCNC.
net spindle-position encoder.3.position => motion.spindle-revs
net spindle-velocity encoder.3.velocity => motion.spindle-speed-in
net spindle-index-enable encoder.3.index-enable <=> motion.spindle-index-enable

# connect the HAL encoder inputs to the real encoder.
net spindle-phase-a encoder.3.phase-A <= parport.0.pin-10-in
net spindle-phase-b encoder.3.phase-B
net spindle-index encoder.3.phase-Z <= parport.0.pin-11-in

Yes no problem with Linux cnc to have Spindle Synchronized, takes a bit to set it up, there are many that have done it so there should be plenty of help if you need it, so your Encoder needs to suit for Linux cnc software / Hardware, your encoder would be connected to the spindle and nothing is needed for the VFD, the spindle speed is synchronized with the Z axes feed rate, so in this case the VFD is just running at a set speed

[xrayxray]

Thanks Mactek,
It's all a big learning curve for me...but well worth it, A question tho....I had intended to fit a tool holder tray at the far end....is it possible for the tools too be engaged and changed with the positioning of the spindle in XY and Zed and the spindle to rotate to a position where locks into the tool holders spindle dogs ?
This will be a modification done at a later date after the machine has been running for some months.

Cheers.

[Al_The_Man]

...I had intended to fit a tool holder tray at the far end....is it possible for the tools too be engaged and changed with the positioning of the spindle in XY and Zed and the spindle to rotate to a position where locks into the tool holders spindle dogs ?
.

Most commercial machines that have T.C. systems do this, but it requires spindle positioning not just velocity control.
IOW, some servo action positioning.
Al.

[mactec54]

Thanks Mactek,
It's all a big learning curve for me...but well worth it, A question tho....I had intended to fit a tool holder tray at the far end....is it possible for the tools too be engaged and changed with the positioning of the spindle in XY and Zed and the spindle to rotate to a position where locks into the tool holders spindle dogs ?
This will be a modification done at a later date after the machine has been running for some months.

Cheers.

Something for you to look at, it's called spindle orientation, and can be done with a code M19 is the standard code used, or just a tool call will do it also T1M6 or what ever tool number you are using

[xrayxray]

Hi Spumco,
I have been going through the posts here and checking out things myself.....sounds like if I take up your offer and replicate your system then it will meet my requirements.

Been reading up on Linuxcnc and from what I can gather most of the spindle orientation, spindle position and speed is software controlled by setting parameters in Hal and Pid...might be wrong too....that would mean that the vfd wouldn't need encoder signals just linuxcnc.....I'm way over my head here and as you say...overwhelming.

Someone might have to point me in the right direction here so I can read up and get a better understanding.....so many google articles written in a language I can't understand yet.

I'm finding this subject fascinating and frustrating...but good fun too.

Cheers.

[spumco]

xrayxray,

Of course I'll be happy to help, but remember that I'm maybe a half-step ahead of you, and there are some genuine experts lurking on CNCzone. One thing I will not be able to help with is LinuxCNC. I have no clue how to set it up, run it, or even what the GUI looks like. It was an option when I was starting to plan my mill overhaul, but my brain started draining out my ear holes when I was trying to understand some of the LinuxCNC Wiki articles. That, and the Mesa cards overwhelmed me.

On to the VFD/encoder...

Mactec54 is, of course, correct that you don't need to send an encoder signal to the VFD for rigid tapping.

Assuming that LinuxCNC can 'gear' the Z-axis to the spindle, here's how I think it works (more or less)

1. The motion software/controller sets the spindle spinning with a 0-10v signal according to your desired RPM
2. The software, using the feed per rev parameter in the tapping G-code you've programmed, figures out how many Z-axis steps are needed per rev.
3. As soon as the index signal is received, the motion controller/software pulses the Z-axis steps in a ratio that follows the spindle revolutions, based on the encoder signals. Note that the VFD/motor need not be spinning at a terribly constant speed - the motion controller will adjust the Z-axis to 'follow' the spindle even if the speed is fluctuating.
4. Once the correct number of steps is reached (or a little before) for the bottom of the hole (or the lowest point in the cycle), the controller reverses the spindle and the Z-axis follows the spindle back up.
5. Peck tapping is basically the same thing, just with one (or more) reverses some distance down the rabbit hole before completing the cycle.

Items of interest:

• The spindle can't reverse instantly, even with a swanky servo-driven spindle. Do not assume you can tap right to the bottom of a blind hole without giving yourself some cushion for over-travel. Practical experimentation with different size/type/material taps and stock are needed to know how close to the "SNAP-Bugger!" line you can approach.
• One of the coolest things I've done (so far) is program a tapping cycle with no Sxxx or M3 command. I then grabbed the (empty) tool holder and started twisting. Once the index signal reached the controller the cycle started and I could raise and lower the spindle head like it was actually geared to the spindle rotation. Maybe dumb or dull to most people, but this was unbelievably satisfying emotionally after gutting a CNC mill with no electrical or electronic training 6 months previously. In fact, this technique is very useful to know if the thread lead/TPI you want is what you're going to get if you stick an indicator in the spindle.

Here's my take on the encoder: No, you don't need an encoder to the VFD. But... why not connect it even if it's not an absolute requirement?

Pros:

1. The Hitachi VFD manual indicates that the VFD can provide significantly greater low-speed torque if it has motor rotation feedback. 200% of rating vs. 150% for sensorless vector mode. Free horsepower!
2. In addition to the low-speed torque bonus, the manual indicates that low-speed operation (<500-ish RPM, or whatever that is in motor frequency) is also significantly more precise. If you command 100RPM, you'll get 100RPM, period. With no encoder feedback to the VFD, you'll get 100-ish RPM. The only variable for motor speed is the stability of the 0-10v signal being sent to it. If your spindle control board (or circuit, if it's on the BOB) sucks, well then...
3. I suspect - but don't have the experience or training to state as fact - that more precise spindle speed during tapping (or any machining) will result in better threads. If the spindle is accelerating and decelerating constantly during the tap cycle - even just a bit - then you may be risking a broken tap or buggered threads. Or at least marginally acceptable threads and probably shorter tap life. Your machine looks like a router so it won't be particularly rigid; you aren't going to be rigid tapping any Inconel without a few modifications... But that doesn't mean you need to put up with crappy threads in the aluminum or mild steel stock you'll likely be working with.

Cons:

1. A few extra wires - three, to be exact. One wire for A+, one for B+, and one for ground. You're already powering the encoder since you MUST have it for the motion controller.
2. A fourth wire - maybe - for the Z+ and a couple more for the homing initiation cycle if you get an ATC and need to do spindle orientation outside of LinuxCNC.
3. Slightly more expensive encoder; The difference between the same encoders, one with single-ended and the other with differential outputs, was about $25US for me. This fell in to the 'no-brainer' category, because as I mentioned earlier I just used all six output signals as single-ended and sent three to the BOB and three to the VFD. Using a double-height DIN-rail terminal block made it simple to wire and then send the signals on their way. Note that this is probably a very, very bad idea if you put the terminal block, BOB, and VFD in the same electrical enclosure as the terminal block and unshielded wire ends are now a great place for electrical noise to corrupt the encoder signal. You should start becoming paranoid about EMI and shielding now, before you start having mystery problems.
4. You're using up two or three of the seven programmable inputs on the VFD. These inputs are finite - but the EA terminal is dedicated to encoder input signals, so it's not like it's available for some other future function. The EB terminal is able to be programmed for other functions, but really - what else do you need to tell the VFD to do? Turn left, turn right, stop, reset, ohcrapestop? Maybe "here is home, now go there" would be a very optional function.

So, for a negligible amount of work and money, you can have more torque at low speed (big-a$$ drills! big-a$$ taps!), more precise spindle speeds throughout the RPM range, and possibly better threads and tap life. If you were asking whether you should buy a new VFD with encoder inputs and an encoder, then maybe the answer would be - don't bother. But you already have (or will have) the three most expensive parts - a VFD with encoder-capable inputs, an encoder, and a not-crappy motor.

How much effort/money is a few feet more of 18-24ga shielded wire?

Also note that the "complimentary outputs" that the nice people from Omron mentioned are simply the same thing as 'differential outputs' I've been jabbering about. Here's a nice encoder that's been recommended to me:

AMT112Q-V CUI Inc. | Sensors, Transducers | DigiKey
http://www.cui.com/product/resource/amt11-v.pdf

For $50AUD, how can you lose?

-Spumco

[xrayxray]

Hi Spumco....great advise...I will keep studying Linuxcnc ...lots to learn.
Yea no inconel to be cut on my machine....but my machine is definitely more rigid than a standard gantry router, and lots of people run them too fast...let the cutter have a chance at doing what it's designed for, time will tell tho if i can get an acceptable tolerance.

Thanks for the encoder suggestion...will follow up.

Linuxcnc can be downloaded and run as a live OS off a DVD or memory stick....no install necessary if you want to look around.
Optional Gui's for download and install to give it that personal touch.

Yea my brains in overload getting my head around LinuxCNC... but it's not entirely LinuxCNC it's CNC in general, plenty of new terms to understand,your posts are a huge help and very appreciated ....you might be able to understand it better now you have experience with other software.

Cheers.