[keebler303]

I'd recommend an MP3 player or another computer. Obviously running anything else but mach will impact PC performance, though it may not cause any problems with your machine control.

I attached a screen capture of the kernel speed setting. The kernel speed is what determines how many pulses per second you can output. If your machine is not super fast, it is foolish to have the kernel speed set too high.

The motor tuning graphic shows you how close to max speed you are with your current kernel setting. If you are only half way up the graph with your speed profile, you should drop down to the next slower kernel. If you need to go faster than the max on the graph, you need to bump it up to the next faster kernel speed. The best responsiveness will always be had when using the slowest kernel speed possible.

Matt

Edit: The picture didn't attach, it is from here: http://www.aquickcnc.com/images/tuto...figuration.jpg

[nateman_doo]

I'd recommend an MP3 player or another computer. Obviously running anything else but mach will impact PC performance, though it may not cause any problems with your machine control.

I attached a screen capture of the kernel speed setting. The kernel speed is what determines how many pulses per second you can output. If your machine is not super fast, it is foolish to have the kernel speed set too high.

The motor tuning graphic shows you how close to max speed you are with your current kernel setting. If you are only half way up the graph with your speed profile, you should drop down to the next slower kernel. If you need to go faster than the max on the graph, you need to bump it up to the next faster kernel speed. The best responsiveness will always be had when using the slowest kernel speed possible.

Matt

Edit: The picture didn't attach, it is from here: http://www.aquickcnc.com/images/tuto...figuration.jpg

Then its probably whatever the default is. Been doing winamp for about 3 years on the CNC computer (have used winamp religiously for around 16 years though) Didn't think it was that bad?

Funny: when looking at the pic, I clicked the "OK" button on the pic and wondered for a second why it wasn't closing and coming back here!

[nateman_doo]

Mach3 has a charge pump circuit driver built in. It's a 5khz step pulse so like enabling another axis. I use it on my BoB, should put minimal additional strain on Mach.

As far as your spindle, get an AC sensorless vector drive! It'll cost a lil more but unlike the garden variety V/Hz VFD's it has encoderless feedback which monitors the voltage/current on the motor wires to maintain constant speed or torque all the way down to 5-10% of rated speed. Pretty much a necessity for using large diameter drills or milling steel at low speed and high feed. I actually use one of the cheap Chinese V/Hz VFD's which actually works pretty well but I have to keep my spindle speed above 30% for decent torque. It even has a rudimentary constant speed feedback mechanism where an increase in motor current (indicating rotor slip) causes a corresponding increase in the driving frequency. Still not as good as true vector control which is on my definite upgrades list.

GS3-22P0 Would do nicely. Also has an expansion slot for an encoder reader so you could really get fancy with full spindle indexing.

Isn't a sensor supposed to go on the motor for a more accurate reading? How would you do tapping with the sensorless vector? Sounds like its an easy way out, or am I still confused? I want mach to control the spindle as well. I still have lots to learn about this part.

[keebler303]

Then its probably whatever the default is. Been doing winamp for about 3 years on the CNC computer (have used winamp religiously for around 16 years though) Didn't think it was that bad?

Funny: when looking at the pic, I clicked the "OK" button on the pic and wondered for a second why it wasn't closing and coming back here!

If your computer is completely loaded down, getting rid of winamp may help. If it works ok, then do what you like.

[nateman_doo]

Figured faster processors would help more then anything .

So I just came back from Home Depot on my lunch break with some assorted aluminum angle. I think I will be able to come up with an effective swarf guard tonight.

[keebler303]

Isn't a sensor supposed to go on the motor for a more accurate reading? How would you do tapping with the sensorless vector? Sounds like its an easy way out, or am I still confused? I want mach to control the spindle as well. I still have lots to learn about this part.

V/Hz is the cheapest control method. Voltage is increased as frequency (speed) is increased, hence being known as V/Hz. Normally rated for 10:1 speed (operation down to 1/10 of nameplate rating)

Sensorless vector actually measures phase currents so it can more accurately control the motor and so you get better performance. Normally rated for 100:1 speed (operation down to 1/100 of nameplate rating)

Sensored vector (closed loop vector) has a proper encoder on the motor and can operate down to 0 speed (stopped) at full rated torque. This is the best you can get without going to a servo. Normally rated for 1000:1 speed (operation down to 1/1000 of nameplate rating) which is basically zero.

You would most likely benefit greatly from sensorless vector control and would not likely benefit from closed loop vector control because you aren't going to be operating at near zero speed.

Another thing to keep in mind is that shaft mounted cooling fans can't keep the motor cool once you slow down too much. For this reason, a lot of "inverter duty" motors are blower cooled, which means they have a separate motor for cooling which runs constantly, regardless of the actual motor speed.

The encoder for mach is a much more simplistic device. If you aren't doing threading and you have a sensorless vector drive, you probably don't need feedback to mach because the speed you set will be the speed it goes within a percent or so.

Matt

[nateman_doo]

So the sensorless vector will still do tapping? I dont understand what you mean by 1/100 etc of nameplate rating.

[nateman_doo]

here is the motor specs:

[keebler303]

The 1/100 etc. is just a rule of thumb, not exact science. Assuming 1/100 speed means that you can get acceptable performance down to 1/100 of the rated speed of the motor. Your motor is rated for 3360 RPM so 1/100 would be about 34 RPM. That is probably being quite optimistic as I doubt you would be able to run with much torque at 34 RPM.

Here is a good paper that explains a lot. Admittedly I did not read most of it but it discusses the basics as well as the three control types I mentioned earlier.

http://www.industry.usa.siemens.com/...tion-guide.pdf

As far as I know, mach cannot do rigid tapping regardless of the spindle control mode. You might be able to do it using a tension/compression tap holder or a tapmatic head made for CNC use. These will give you a little leeway between the spindle feed and Z feed. I've never done CNC tapping so I can't say much for certain. I know on the real deals they have a real encoder mounted on the spindle to synchronize tapping.

In short, sensorless vector is not sufficient for rigid tapping, however it is probably good enough for some "non-rigid" tapping using the above mentioned attachments.

Matt

[nateman_doo]

34 RPM is pretty slow. I will read that paper in the morning. Right now Im pretty spent and i just made some stellar progress with the swarf guards.







[ame=http://www.youtube.com/watch?v=glqGqWJwtoY]Swarf guard - YouTube[/ame]

[nateman_doo]

I also noticed that they aren't cheap?! Many hundreds of dollars for one of those motors. So it seems I have a choice between the V/Hz and save some of a GS2 VFD ($250), Spend a bit more for the sensorless vector GS3 ($300), start researching a bolt on encoder on top of VFD, or buy a motor with encoder($$$!!!) and VFD.

[Bloy2004]

Very nice mill bed/table system!
It will be interesting to see how far you go into the electronic bells and whistles.
I suppose it will be up to not what you need, but rather what you want.

I've made additions(not posted) over the years to my router build ...there's always somethin'....

..by the way.. I've run TV through an ATI All-in-one video card often while simultaneously cutting without problems. But there are risks.

[nateman_doo]

Thanks! I am especially proud of the swarf guards and the wire carrier. 2 things I never had before and just make the machine a pleasure to stare at. Shame the cable carrier is going to be covered by a neoprene rubber sheet and will never be seen.

I read that the VFD that Tormach uses is a sensorless vector type. So, I guess I will be looking at the GS3-22P0

[Bloy2004]

post deleted.
please disregard... video cleared up my observation.

..again, nice work!

[nateman_doo]

I read an interesting paper from Tormach about the 3 different modes of VFD's (V/Hz-SL/V-CL/V . They selected the sensorless vector (SL/V) for 2 reasons. It gave them accurate enough feedback, and the more accurate Closed loop vector (CL/V) gave the machine no usable advantage.

That being said, I was looking at another part for the GS3 drive and its the GS3-FB card, which turns the drive into a CL/V drive for about 60 dollars. It seems to mate into the GS-3. It got me thinking though, The schematic shows a Pulse Generator and an RPM meter. I get you can probably purchase an RPM meter, but what got me thinking is do I really want the MOTOR rpm... or the SPINDLE rpm. Obviously I want the spindle RPM, but how does the motor RPM relate to the spindle RPM? Obviously its mathimatical in regards to the belt drive, but how would I see the spindle speed in mach? is there a formula you enter where it reads the motor RPM, and give me the spindle RPM? So the motor will be reading 3K on the GS3 unit, but mach will show me the calculated spindle speed?

[nateman_doo]

post deleted.
please disregard... video cleared up my observation.

..again, nice work!

What observation?

[keebler303]

I read an interesting paper from Tormach about the 3 different modes of VFD's (V/Hz-SL/V-CL/V . They selected the sensorless vector (SL/V) for 2 reasons. It gave them accurate enough feedback, and the more accurate Closed loop vector (CL/V) gave the machine no usable advantage.

That being said, I was looking at another part for the GS3 drive and its the GS3-FB card, which turns the drive into a CL/V drive for about 60 dollars. It seems to mate into the GS-3. It got me thinking though, The schematic shows a Pulse Generator and an RPM meter. I get you can probably purchase an RPM meter, but what got me thinking is do I really want the MOTOR rpm... or the SPINDLE rpm. Obviously I want the spindle RPM, but how does the motor RPM relate to the spindle RPM? Obviously its mathimatical in regards to the belt drive, but how would I see the spindle speed in mach? is there a formula you enter where it reads the motor RPM, and give me the spindle RPM? So the motor will be reading 3K on the GS3 unit, but mach will show me the calculated spindle speed?

Mach can't handle the high frequency of an real encoder. If you tied it into mach, you would probably have to use the index pulse on the encoder (hopefully it has one). Mach has settings you can adjust so that the encoder would read in spindle RPM.

Matt

[nateman_doo]

Can you elaborate on that?

[keebler303]

Encoder basics: http://www.theencodercompany.co.uk/p...er_outputs.pdf

I'll use this motor as an example: Y536-A772 | 1 hp Inverter-duty AC Motor w/encoder: 143TC, 1800 RPM

It comes with a 1024 PPR encoder. That means the A channel outputs 1024 pulses per revolution and the B does the same. The C (or Z channel) is called the index channel and it outputs only 1 pulse per entire motor revolution. It is like an absolute reference to the angle of the motor shaft.

Assume you are running at 3600 RPM. 1024 pulses per rev at 3600 rpm is 3600x1024 = 3686400 pulses per minute. Divide by 60 and you get 61,440 pulses per second.

Look in the mach manual and you will see that it is not capable of receiving pulses anywhere near that quickly. Most guys with spindle encoders are using something like 4 or 8 or 10 pulses per revolution which will give mach a usable pulse train with which to measure speed. Here is one example of a simple "DIY" tachometer: Camtronics, inc. -- CNC with Dan Mauch

If you put a real encoder on your motor, the encoder pulses will be too fast for mach to read but since the index pulse is only once per revolution, the pulse frequency is 1024 times slower (for the above motor). Mach would have no problem measuring speed using a single pulse per revolution provided that the motor speed was not too slow. I am not sure of the exact limits but you will lose accuracy if the frequency isn't between some lower and upper limits.

In the mach encoder setup, you can specify how many pulses per rev you have. You can also create a gear or pulley table with all the available ratios listed and I think that can be used to correct for the ratio between motor and spindle. It has been 4 or 5 years since I messed with a tach using mach so i don't remember much but i know it can be done.

Is that elaborate enough?

Matt

[nateman_doo]

probably a bit over my head - plus I was looking at that motor for almost $1000.00. Not going to happen when I already have the brand new motor. So I am trying to figure out that when I get the GS3, I can still control it with the pendant, but also send the controller info from mach, and mach can calculate from what the motor is spinning at, to what the spindle actually is when I use the "S" command in a line of g code?