Machsupport Forum
Mach Discussion => Mach4 General Discussion => Topic started by: Azalin on November 15, 2017, 08:10:47 AM
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Hi,
I just purchased Mach4 and the Darwin PP plugin for my retrofitted lathe. The lathe worked well with Mach3 so I thought it would be easier to setup Mach4 but I realized it is the opposite. Anyway, please read my questions. Any help would be appreciated.
1- In Mach3, I assigned the Enable to pin 1. I did the same on Darwin and Mach3 Mach config. In Darwin Output screen when the "Freq when active" is set to 0 then it doesn't work. Under the text field it says "For PWM enter 1/2 of the base freq. What is the base freq? The only frequency I set is the PWM base frequency for spindle and it is 300.
2- I have set the Charge pump to pin 17. In Mach3 when I hit the Reset button the Enable and Charge pump was triggering at the same time. When "Enable" is active the charge pump become active. When "Enable" id inactive the charge pump become inactive. This works fine in Mach3. In Mach4 I have no idea how to map the "enable" and "charge pump" together.
3- In Darwin Motor Config tab I enabled only 2 motors (Motor #0 for X and Motor #1 for Z). In the same screen there are 2 drop-down menus labeled "X axis" and "Y axis". For the X axis I select Axis0. Fine. But what should I do for the Z? There is no drop-down for the Z. I think this screen is developed for mill?
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Hi,
I suspect that you will find more answers in the Darwin Parallel Port discussion thread on this board.
There has been some discussion here lately about the charge pump in Mach4/Darwin PP and the upshot is that it doesn't work too well,
I understand that most people no longer consider it necessary and don't use it.
Craig
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Hi,
just had a thought about another question you raised.
On Configure/Mach/General page check the <X-Z> Active plane and then try assigning motors etc.
raig
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I did this but I think it doesn't effect the Darwin. In motor config screen in Darwin the Y drop down is menu still there.
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Hi Azalin,
can't be of much help, I don't use Darwin but rather an ESS so I was just guessing.
Craig
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Thank you Craig :)
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Charge Pump issue discussed here.
http://www.machsupport.com/forum/index.php/topic,27194.msg245834.html#msg245834
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Oh god. 109 pages. But thanks Gerry.
I feel hopeless. I think it's better I get an Ethernet M16 board.
Do they accept return/cancel order for the Darwin plugin?
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Hi,
Ethernet M16 board? I don't recall ever hearing of a board of that name being Mach4 capable.
ESS, PMDX various, PoKeys various, CNCDrive some,Vital Systems various, yes, but Ethernet M16 no, never.
Craig
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It's pokeys branded.
https://cnc4pc.com/m16-pokeys-motion-motherboard-for-mach4.html (https://cnc4pc.com/m16-pokeys-motion-motherboard-for-mach4.html)
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Hi,
kool, Ok a PoKeys 57 on a breakout board.
I had a conversation with NeoT the moderator of the PoKeys board on this forum and the bare 57E or 57U have a couple
of limitations when used as a CNC controller but those shortcomings are addressed in the 57CNC with fullspeed pulserates
and all six axes capable.
Craig
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Hi Azalin,
I found the thread:
http://www.machsupport.com/forum/index.php/topic,35622.0.html (http://www.machsupport.com/forum/index.php/topic,35622.0.html)
It seems to me that if you are contemplating buying an external motion controller then it makes sense to get one that will meet your needs now and someway into
the future. If you follow my argument then the PoKeys 57CNC is a better choice than the 57E or 57U, regrettably somewhat more expensive too.
Using that same logic then the 57CNC is competing with the ESS by Warp9 and the PMDX-424. Both are good, both manufacturers support is excellent and they all
cost near enough to the same. The 57CNC is remarkably flexible with analogue inputs that the other two lack and also the low level programming available in the
PoKeys products. The Warp9 and PMDX products have grown and developed as Mach specific products. When I was selecting a controller it was my understanding
of the parallel port that I had been using for some years which leaned me to both PMDX and Warp9. In the event I chose an ESS. I would have been happy with
any of these three products. Now that my understanding has broadened somewhat from the pure PP mentality the 57CNC looks very attractive.
I had originally intended to use the Darwin PP and even bought a license but never got around to using it. Once I had the ESS sorted and running I didn't want to go
back. The smoothness of motion allowed me to push up my traverse speeds by 33% without any extra heat generated in my steppers. They even sound better...they seem
to sing rather than squawk like the did on PP.
I rather think that NFS might decline a refund. My suggestion is carry on with Darwin, get it working as well a you can while you formulate a plan for future development.
A good external motion controller like the ones I've mentioned would be a superb investment in your hobby.
Craig
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Hi Craig,
I get the Darwin working but I still have a problem. When I jumper to disable the safety charge pump then its fine but when I enable it and try to activate trough Darwin its a big mess. I hit the Enable button, Darwin opens all outputs including spindle relays. Mach3 only opens the outputs that are used by the system.
Another problem, Darwin can't keep the safety charge pump steady on and so the outputs. The LED's of the outputs are flickering. It's like power goes on and off repeatedly.
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Hi Azalin,
the charge pump is old school and no-one uses it much any more. Sage has found that it doesn't work too well in Mach4. Why bother with it?
When was the last time you had the charge pump activate a shutdown for safety in Mach3? I've asked quite a few people and they've all answered never.
If you think the charge pump is a deal breaker then go spend $200 on an external motion controller; if you don't have the money or don't want to spend it
then drop the charge pump idea.
Craig
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Hi,
this is what Sage had to say:
Does anyone have the parallel port working with Mach4. Specifically with the charge pump activated? I'd be interested in comparing configurations.
I have been in contact (for several months) with NFS support and they have confirmed that (as I observed) the charge pump signal from Darwin initially comes up and then fails just after Mach4 startup. It requires a toggle of the enable / disable screen button to get it going again. This would not be a big problem except that when if fails the DRO's still change but the axis' do not move because the lack of charge pump signal has disabled the drives. So then the disable/enable trick has to be done and a re-calibrate is required.
In my latest exchange with support they have indicated that they have no (financial) interest in working further to correct the issue and suggest I purchase a motion controller instead. Fair enough I guess but it makes me wonder why they continue to sell the parallel port plug-in (Darwin) when it has this bug. Then it makes me wonder - if they have sold more than the one I have - what have others done to make it work. Maybe I've missed something.
So, Is the parallel port finally dead?
Sage
I have some sympathy in the sense that an old Mach feature no longer works but at the same time I want to say 'who bloody cares'...hardly anyone uses it anymore.
Art Fennerty wrote Darwin just like he wrote Machs parallel port driver before. NFS have no financial interest in fixing the charge pump. Single point lathe threading, or
backlash compensation, or THC, or a touch module....yes they are probably very interested in those because the vast majority of Mach users want and appreciate such
features, but a charge pump?.
Craig
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I'll argue that the charge pump is still a very useful feature, when used to prevent output pins from randomly toggling high/low before software has full control.
Maybe Mach4, and Mach4 specific hardware has other ways to handle this, but there is still a lot of hardware out there that can behave very differently.
I was using an MB2 breakout board with a UC300ETH. Because the MB2 was designed for the ESS, it didn't work the same way with the UC300ETH, resulting in my spindle turning on when I powered up the system. The Charge Pump can prevent that.
I also use the Charge Pump to prevent my drives from being powered until the software is up and running.
Having said that, imo, it makes no sense at all to spend $200 on Mach4 and try to use the parallel port, when Darwin is so severely limited.
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OK I've given up the Darvin with safety charge pump.
I have more problems. One is: In Darvin, I set the input for the index to pin 15. I tested and the signal and its OK. Then I did the mapping for the index in Mach config screen. When I start the spindle I can't get an RPM reading. What else has to be done in order to get the indexing working?
Mach3 has a nice Diagnostics screen that I can see all the inputs/outputs status. Is there a similar plugin/screen for Mach4?
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Hi Azalin,
what screenset are you using?
The wx4.set has a Machine Diagnostics tab and top right of Input Signal LEDs is the Index LED. At any realistic spindle speed it will be too quick for the
LED but it is there.
Craig
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Hi,
only guessing here but have you set realistic max and min on Configure/Mach/Spindle page?
Craig
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Hi Craig,
Yes, I configured that but didn't help.
As the lathe I have has single gearing, the gear ratio is 1:1. The max motor/spindle rpm is 1510. I control the motor trough a VFD.
I guess I need to leave Step/Dir settings unchecked as the spindle motor is not a stepper.
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Hi Azalin,
what screenset are you using?
The wx4.set has a Machine Diagnostics tab and top right of Input Signal LEDs is the Index LED. At any realistic spindle speed it will be too quick for the
LED but it is there.
Craig
I don't have the wx4.set file in Screens folder. I'll try to find a link to download that file.
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I think the vx4.set and vx6.set files are removed or renamed in recent Mach4 versions.
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Hi Azalin,
I downloaded the latest Mach4 build over the weekend. wx4.set is included.
Craig
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Was the build you have installed Hobby or Industrial? I installed Hobby version.
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Hi Azalin,
hobby, at work at the moment so can't confirm build number but think its 3481.
Craig
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Hi Azalin,
at home and yes I have just downloaded build 3481.
C:\Mach4Hobby\Screens...and there is a bunch of them including one that I personalised ESSMillwx4.set so when I customise it it doesn't get overwritten
the next time I get the latest and greatest build.
Craig
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Hi Craig,
I was too busy. I'll try to get the thing working today and I'll let you know.
Thanks,
Suat
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Looks like the vx4 and vx6 sets are installed when you do a full installation. I only selected lathe option setup so the vx files didn't get installed.
Anyway, I tried the vx4 and vx6 screensets and yes, the diagnostics tab looks similar to the one in Mach3.
When I start the spindle by clicking the CW button in Mach4 the spindle starts revving and the "Index" indicator in Diag tab starts blinking however where the heck (sorry I'm getting tired of this Mach4 thing) is the real reading? : ) I don't see anywhere the real RPM from the index sensor.
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Hi,
I don't know if the lathe set handles it differently but the index signal is taken by Mach, averaged and converted into
an rpm number using the range info on the spindle settings page and displayed in the True RPM DRO in the wx4.set.
This is done automatically by Mach, you have little control over it nor even view how its done.
Have you set up the range info? Configure/Mach/Spindle....in particular set up a realistic max and min.
Craig
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Yes, Min 0, Max 1510
If you mean the area in red, I only see there a calculated value in "True RPM" field. Not the RPM from the index sensor.
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Note: I just installed Mach4 to another computer to take the screenshot. It's not from the computer that I use for the Lathe.
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Hi,
I believe they are one in the same. The index pulse is converted to True RPM. If the feedback ratio on the spindle
range page is equal to one the the True RPM is the same as the Index RPM.
If you had two pulses per rev of the spindle you would set the feed back ratio to 2 (0.5??) and the index RPM would
be correctly converted to spindle RPM.
Craig
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I think I'm doing this all wrong. The in the video has a similar setup. I'll try the same.
https://youtu.be/7g_4gjZMA3g (https://youtu.be/7g_4gjZMA3g)
Sent from my MI 5s Plus using Tapatalk
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Hi Azalin,
I think we often spend too much time worrying about spindle speed. Quite a few of the jobs I do on my mill are engraving type jobs, PCB routing particularly.
All I require is that the spindle starts, go to max RPM and stay that way until the job is done. I don't need/want it to go backwards, I don't care what the true
RPM is, I mean I can tell at a glance whether the spindle is going OK.
May I suggest rather than attempting to set your machine up so that you have fine speed control and true speed feedback with all the complication and confusion
of software setup and hardware compatibility that you settle for a simpler solution. When your comfortable with that then start extending your control and then
only to the extent required to do the machining you require. Do you actually require precise indexing and speed control for rigid tapping UNLESS you are doing
rigid tapping?
The video you linked is a very simple and common set up. It defines two outputs: one for ON/OFF control and the other as a PWM signal that results in a 0-10V
analogue signal to your VFD/spindle driver. It may be, like my engraving job, that you don't need the PWM speed control, you might have a potentiometer and
knob that you can lean over and tweak to do the job at hand. If you need to be able to go in reverse you will need more outputs.
You could use as few as two: one for FWD and the other as REV and with neither output active STOP. Or you could have three outputs: one for ON/OFF,
and the other two for FWD and REV. Use whatever seems simplest to adapt to the input circuit of your VFD/driver.
Likewise most VFD/drivers accept an analogue voltage and most BoBs output an analogue voltage usually from a nominated pin so connect one to the other.
At this stage who cares about spindle feedback? You will know immediately if the spindle is doing what its supposed to or close to it. Even if you do have an index
pulse setup and true RPM displayed without some sort of closed control loop you can't adjust the spindle speed anyway. And before you ask Mach is not a closed loop
controller. You will no doubt have seen posts about it and using some clever coding and/or hardware you can induce Mach to close a control loop but its performance
is pretty lethargic. There are external motion controllers that have closed loop control capacity, often called PID, but they cost extra, a lot extra as a rule and it
begs the question 'how precise/detailed/accurate/dynamic do I require my spindle speed control to do my machining?'
If you find that you need really precise indexing and speed control for rigid tapping say the buy yourself a decent AC servo and drive. You can shag around with
feedback controllers and encoders until 'the cows come home' and still not match the control offered by a matched AC servo and drive. All that is required with such
a matched pair is a Step/Direction signal pair....no encoder feedback, no PID tuning, no headaches!
Keep your spindle speed control solution as simple and cheap as you can...save your time and dollars for other things!
Craig
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Hi Craig,
The machine I am trying to setup is a lathe. I need spindle indexing for threading. I have to get it done.
Best,
Suat
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Hi,
OK, you require indexing....start by getting the spindle to work! If you don't have control of the spindle then indexing is pointless.
Craig
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Hi,
my comment about the suitability of an AC servo as a spindle motor applies equally to a lathe spindle.
Mach requires one pulse per rev, an index, to calculate and synchronise a thread. Mach assumes that the speed is constant even when the tool engages the
material and starts cutting. We all know that is never actually the case, the spindle always slows a little. Even with closed loop control a feedback of one pulse
per rev is not enough for a controller to maintain spindle speed accurately enough for threading.
Most modern AC servos have encoders of 10,000 count per rev and feedback/control loops in the kHz range. The control bandwidth is such that it can maintain
its speed accurately many hundreds of times per revolution which beats the hell out of any other motor with a simple index pulse.
Craig
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Mach requires one pulse per rev, an index, to calculate and synchronise a thread. Mach assumes that the speed is constant even when the tool engages the
material and starts cutting. We all know that is never actually the case, the spindle always slows a little. Even with closed loop control a feedback of one pulse
per rev is not enough for a controller to maintain spindle speed accurately enough for threading.
Sorry Craig but this is not quite true - there are many lathe users threading this way.
Tweakie.
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Guys, I get the spindle working. I mean, M3 and M5 is working. I also get the green light when the index sensor is aligned with the slot on the disc. However, I don't have any index reading. When I hit the CW button in Mach4 the spindle starts rotating but the real spindle speed always zero.
(http://puu.sh/yuq4d.png)
- The index sensor is connected to PIN 15. I did the Darwin setup. Also mapped index to index in Mach inputs screen.
- I set the base PWM frequency in Darwin diagnostics screen to 300.
I wonder why there is no complete documentation for the Darwin plugin.
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And some screenshots of the setup. Please let me know if more info needed.
(http://puu.sh/yuqny.png)
(http://puu.sh/yuqnw.png)
(http://puu.sh/yuqnz.png)
I have played with the index debounce but didn't change anything. I used to use 20 in Mach3.
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Hi Azalin,
AFAIK that all looks good and I don't know why its not working.
Tweakie
Mach requires one pulse per rev, an index, to calculate and synchronise a thread. Mach assumes that the speed is constant even when the tool engages the
material and starts cutting. We all know that is never actually the case, the spindle always slows a little. Even with closed loop control a feedback of one pulse
per rev is not enough for a controller to maintain spindle speed accurately enough for threading.
Sorry Craig but this is not quite true - there are many lathe users threading this way.
My understanding is:
Mach assumes constant speed. If the speed slowed over one revolution as a result of the cutting forces then Mach would attempt to cut the thread but do so
inaccurately. With spindle speed averaging it will take Mach several revolutions before a more accurate estimate of speed is available. If the spindle has significant
inertia and/or power then the speed change will be slight and the thread cut fine. A lightweight or underpowered spindle and the speed change could be significant
and the thread inaccurate.
For situations where the spindle is marginally powered, which is the same as saying taking heavy cuts relative to its power, then a higher bandwidth control
loop makes the most of the power available.
To my knowledge no-one has repealed Nyquist's sampling theorem and the control bandwidth is inextricably linked to the number of pulses per rev.
Several months ago I bought a 1.8kW Allen Bradley servo and drive for a spindle motor. Its encoder is 2000 line or 8000 count per rev with a loop update rate
of 20kHz. It beats any other spindle motor for speed/position accuracy that I've ever come across. Had I not bought one and tried it for myself I would not have
believed how much superior a servo could be over an index pulsed motor.
Craig
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Hi Craig,
I really don't want to get into a discussion about this but...
Even with closed loop control a feedback of one pulse per rev is not enough for a controller to maintain spindle speed accurately enough for threading.
It's perhaps not ideal but that's the way threading has been done with Mach3 (one pulse per rev) .
Tweakie.
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Threading in Mach3 with a single pulse per revolution does rely on
the pulse to measure spindle speed as well as to sync the Z axis
motion at the start of a threading pass.
The spindle speed is not modified by the threading process when
it measures the spindle speed. Only the Z axis traverse rate is
modified.
The Z axis traverse rate is not a regular PID control loop. The new
measurement of the spindle speed is fully adjusted for the change
as soon as it is measured. This is effectively a "P" only control loop.
Only the acceleration limit of the Z axis inhibits instant changes in
the Z axis motion.
Adding a PID speed control loop to the spindle drive may improve
things, but it also runs the risk of the two feedback loops interacting
in difficult to analyze ways. A strong servo with direct PID feedback
control will likely improve theading without causing interactions. Using
the regular speed control input to a VFD and software in Mach making
speed change requests will likely be too slow and complicate things.
The Z axis threading control loop is not ideal, but as stated, with a
strong enough spindle motor and sufficient spindle inertia, it does work
for "hobby grade" theading.
For machines run by a motion controller in Mach3 or Mach4 and
utilizing more than one pulse per revolution, better control loops
are possible. The nature of the loop will depend on the motion
control vendor because they can filter the speed feedback as
desired.
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Don't know what the difference is in Mach4 threading as compared to Mach3.
This is how the threading works in Mach 3 and all info below is from Threading On The Lathe writeup done
some 9 years ago.
One complete thread cycle or pass is basically composed of the following:
Trigger – index pulse is seen and activate start of movement
Accelerate – move to an exact Z location relative to the turning spindle
Threading – move / control the tool such that the feedrate is correct relative to spindle rpm
Pullout – the tool is removed at the end of the thread
Retract – the tool is moved back to a starting point for repeat of the cycle
During the threading the rpm is monitored by the controller for variations and Mach plans on how to modify the next threading pass such that the Z axis movement will maintain the lead of the screw. Testing has shown that the lead is tightly controlled to a fine tolerance such that a near perfect thread can be produced if the lathe system is capable of it. Should the spindle slow down, Mach will change the Z movement to try maintaining the lead. Spindle slowdown in the range of 10 to 75% may be the range, but, as of this writing has not been tested. Past testing of past Mach versions on spindle slowdown is relative but not definitive for the new threading version.
3.9 MOTOR - GENERAL SLOWDOWN / POWER / EFFECT ON TREAD’G
WW:
The rpm stability and power delivered to the spindle will affect how Mach plans the Z motion
for threading. Motor rpm does change and in threading it can have a dramatic effect during the threading cycle. The horsepower required for making a cut can be calculated, and actual cutting tests by the Society of Manufacturing Engineers have provided practical ways of calculating the power. General formulas for horsepower are helpful for comparisons, ie; stepper hp delivered verses spindle hp, but, calculations are not “exact” / subjective, and frankly is beyond the average users understanding or application of them.
The stepper motor needs to have adequate power to move the Z axis during threading. Thus,
during threading, the combination is a “chain’ so to speak, and the application of the power is only as good as the weakest link in the chain. Changing gearing / belt ratio’s for either motor
along with driver setup ( ie; voltage / amperage , etc ) can improve the operating range of the “system”. The stepper must be able to accelerate / decelerate within the parameters the user
defines in the Gcode. Experience gained by just cutting a range of threads, using different cut depths, rpm, cutting methods, etc is highly suggested.
See Section 4, page 22 of 51, Figure 4.4 for the basis of lead tolerance. See page 8 of 5, 3.6.1 for an example of testing.
Just remember this:
Threading will only be as good as "YOUR" lathe "SYSTEM". A "perfect" software controller in all aspects
won't help a piece of poo lathe produce good threads.
RICH
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Is this an answer for me or for @joeaverage? :)
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Hi Azalin,
sounds my like general advice rather than to you specifically.
Are you using the lathe screen set or the mill set?. I was going to suggest setting up a profile in Mill to see if the
index/DRO True Speed function works.
Craig
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Hi Craig,
I already did. I also created a new lathe profile. I have uploaded the profile folder if you (or anyone else wants to help) want to take a look.
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Hi Azalin,
I'll try it tonite after work . The code for the speed estimation and synchronisation is built into Mach, beyond what
we can see or manipulate. If nothing obvious ocurrs to us then you may be best placed opening a support ticket at
NFS. The only couple of times I have done so worked out well, took a few days but it did happen.
Craig
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Thanks Craig.