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IndustryArena Forum > Other Machines > PCB milling > CNC 3020T-DJ Spindle Control, JP-382A JP-1482
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  1. #21
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    Re: CNC 3020T-DJ Spindle Control, JP-382A JP-1482

    Thanks for the connector info Bob. Was able to locate locally at Mouser. (catalog page)
    I happened to find an unused one in an old computer in the mean time but my main controller is a little different from the 3020, the spindle controller is the same though.

    Now I have to trace the signalling on the controller. Which control on Mach3 can I use to turn the spindle ON/OFF without running a program?

    Louie

  2. #22
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    Re: CNC 3020T-DJ Spindle Control, JP-382A JP-1482

    Louie,

    Have a look at post 1 of this thread by kbOnly. You'll find the information you need there along with a circuit diagram of the spindle controller on-off circuit - at least the bits that you need. You'll need to pick up the Mach3 spindle on/off signal from pin 1 of the parallel port and +5V form your MAIN controller board (i.e. NOT the spindle controller). If you need further clarification, please ask and I'll try to help.

    What equipment are you running Louie and does it already have PWM control?

    Bob

  3. #23
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    Re: CNC 3020T-DJ Spindle Control, JP-382A JP-1482

    Bob,
    My unit is a 3040Z-DQ and have purchased the CamBam/Mach3 bundle for it. All running on a dedicated PC with Win7 32bit.

    I did print out the schematics from kbOnly and managed to confirm that shorting pins 3 and 4 on the JP-1482 will start/stop the spindle.
    It doesn't have the JP-382A controller so I need to find which relay or opto-coupler pin1 controls so I can interface it like you all have done.

    I found a relay with an unterminated output terminal block that I hope is connected to pin 1 of the serial connector but have not taken the board out to trace it.
    I also deciphered the Chinese text next to an LED indicating "Spindle" control, but triggering it is inconsistent.
    If I can manually control from the Mach3 program without running a short G code sprinkled with some M3's and M5's too toggle it, tracing would be grand.

    Thanks,

    Louie

    By the way... I don't have PWM control or the HW/SW switch on back of the controller.

  4. #24
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    Re: CNC 3020T-DJ Spindle Control, JP-382A JP-1482

    First off let me apologize for being AWOL from this thread for so long!! Things have been CRAZY busy here the last few months.

    Anyway...

    Bob, great work! Did you post up the schematic of that board you built? I would like to try and duplicate your work and install it on mine to play with it!

    And next some bad news, my computer that was controlling the CNC crapped out. It was an OLD computer running XP. First the IDE hard drive started rattling to death, then after chucking in a 40gb from the junk box i started having bluescreens, probably a failing stick of memory or who knows what, i don't want to put the time and effort into troubleshooting it when i have some other computers at my disposal. But then i started having control issues thanks to the Parallel port on the newer machines... BUT i solved it! And this could relate to quite a few people using these chinese CNC's and adding the spindle on/off control so i wanted to post back on this!

    I swapped the dying computer for a newer Dell Optiplex 755, yeah not a spring chicken either but running Windows 7 Home Premium 32bit and the best part of all its SATA instead of IDE for the drives, which brings it up to the current generation of computers in that category at least. And it has an SSD so it boots lightning fast and its much more power efficient then the old beast of a desktop that i was using on the machine.

    The problem though was pin 1 of the parallel port was sitting around 3.2v for its high disabled state. The old computer wiggled around at 4.1-4.2v, so as soon as i turned the CNC controller on the spindle spun up and Mach3 couldn't control it whatsoever. If you go back to the first page of this discussion and look at my schematic for the JP-382A Controller you will see that from the four pin header labeled A-Axis there is a 4.7k resistor which goes to the one side of another 4.7k resistor and then to pin 1 of the parallel port. This is the pullup from 5v on that A-Axis connector pin to keep pin 1 of the parallel port at a high state when the spindle isn't enabled.

    The problem is they used it wrong. There should be a 4.7k resistor from 5v to the one pin of the EL817 labeled ENO and another 4.7k resistor from 5v to pin 1 of the parallel port. But they have them in series, i assume to try and cut corners and feed both from one trace over to the A-Axis header. This places a total of 9.4k from 5v to pin 1 of the parallel port. There isn't enough of a pullup to pin 1 with this arrangement for some computers parallel ports!!

    Now there is two ways to fix this.. one is to remove the 4.7k resistor between DDO and ENO, the problem is this requires removing the controller board from the enclosure and the heatsink to get to the components on the bottom of the board, big pain in the rear...

    So here is option two... take a 1k resistor and place it from pin 4 of the A-Axis header, thats the rear most pin of this header, and the other end goes to the left rear pin of the EL817 labeled DDO. This puts the 1k resistor in parallel with the two 4.7k resistors, using some quick math a 9.4k resistance in parallel with 1k of resistance is 904 ohms. So close enough to 1k for me which is what i always use for pullup resistors on logic signals like this.

    This allowed the new computer to once again turn the spindle on and off and no problems!! I just did it quick and dirty by taking a 1k resistor covering it with heatshrink tubing and tack soldering it to the two points and went back to milling PCB's with the new computer after copying the Mach3 directory over from the old computer to maintain all the settings. Quick and easy fix and it should make it work with any computer now regardless of the parallel port's average voltage. If you get one which even the 1k tacked on isn't enough i would go down to a 680 ohm resistor instead, that would be around 630 ohms parallel and should bump up the pullup enough to compensate while still keeping the low state around 2.4-2.5 volts when the spindle is enabled by Mach3, and jumping up to just over 4v when disabled.

    Attachment 263478

  5. #25
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    Re: CNC 3020T-DJ Spindle Control, JP-382A JP-1482

    Good to hear from you again kb0nly but sorry to see you have had bother with your computer. The circuit and board layout diagrams are below...


    Attachment 263528 Attachment 263530

    The circuit board was milled (of course) and I could provide g-code files if you wish.

    The HEX file is attached. A word about the software if I may. It's functional, but should be treated as a beta release. The original source code is written in the excellent Proton BASIC language. If you want the source let me know. It's fairly simple and should easily translate into other BASICS or the likes of C.

    A word or two about the software if I may. About 10 times a second the software measures the period that a single PWM cycle is at logic zero and produces a number typically between 6 and 245. At low RPMs this number is high, and at high RPMs low. The number is then averaged over 4 PWM cycles to reduce the chance of ‘flickering’ between consecutive readings.

    The next stage is to take the PWM number and convert it in such a way that it can be used to control a digital rheostat. In effect the analogue pot on the front panel is being replaced by a digital one. This is not a simple task. For starters, the spindle does not start to rotate until the resistance has been reduced from about 5k to approximately 3.8k. Consequently an offset must be applied to the number fed to the rheostat chip. The second problem is that whilst the numbers produced by the Mach3 software are beautifully linear, the behaviour of the spindle motor is most definitely not. This means that the software not only has to take care of the offset problem, but it must scale the PWM number to correct for the non-linear nature of the Spindle motor before it is transmitted to the rheostat. This it does well, however there are some interesting issues that make life difficult.

    The software aims to spin the motor at a speed (in RPM) near that indicated in the Mach3 software. It is never likely to be an exact match. This is because the spindle speed varies with AC mains voltage in a significant way. The DC supply is not stabilised and there is nothing that can be done about this unless a different, stabilised, power supply is used. A second problem is that the controller has no feedback mechanism which allows the actual spindle speed to be monitored. This means that the software has no method of correcting for motor loading. I’ve tried to compensate for this by having the spindle rotate at a faster rate off load. So, for example, if Mach3 is set at 8000 RPM, then it is likely that the off load spindle speed will be in excess of 9000 RPM. Again the actual speed will depend on the AC mains voltage at the time. All of this said, I’m pretty certain that these problems exist on all the PWM controllers at the budget end of the market.

    If this wasn’t enough, the JP-1482 controller has a couple of interesting features. As I have mentioned in a previous post, the speed at which the spindle rotates is not just dependent on the position of the control knob on the front panel. It can also depend on the previous position of the knob! Try marking a position on the spindle control knob scale about 2/3 of the way along. Start from the minimum setting and rotate the knob to the marked position. Note the spindle speed. Next rotate the knob until you get maximum speed and then move it back to your marked point. Measure the speed once more. You'll find there is a several thousand RPM difference! To overcome this problem, the software looks to see if the user wants to increase or decrease the spindle speed. If the spindle speed is being decreased, then the resistance of the rheostat is set to maximum for a period of 25ms before returning to its correct setting. This makes the JP-1482 controller ‘think’ that the control knob is being rotated from the minimum position. Normally the user will not notice this.

    The second issue is that, although it appears as if rotating the spindle control knob gives a smooth increase or decrease in speed, I’m not certain that this is the case. I suspect that changes in speed, especially at lower RPMs, are incremental. The practical consequence of this is that occasionally, with small speed adjustments, changing the speed in MACH3 does not produce a change in spindle speed. The software is changing the resistance of the rheostat, of that I’m certain. Further investigation is needed.

    MACH3 SETTINGS

    The software is built around some specific settings and are the ones recommended in the controller documentation. These are:

    Kernel Speed: 35000Hz (Do not change.)
    PWM frequency: 200Hz (Do not change.)
    Minimum PWM 10%
    Maximum pulley speed: 11000 rpm (Don’t set a minimum.)

    Please note that the software has a minimum speed of around 2000 RPM.

    I’ll probably spend some time developing this board and software for myself. If I manage to make significant improvements, I’ll post them here. If anyone comes up with a better method of controlling the JP-1482 I hope they’ll do likewise.

    In the mean time if anyone else does try to build this, I’d be interesting in hearing how you get along.

    As always, make sure you know what you are doing around mains voltages. All modifications to your controller are entirely at your own risk.



    Bob

  6. #26
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    Re: CNC 3020T-DJ Spindle Control, JP-382A JP-1482

    Post removed by Mellbreak.

  7. #27
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    Re: CNC 3020T-DJ Spindle Control, JP-382A JP-1482

    New information added to post 25.

    Bob

  8. #28
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    Quote Originally Posted by kb0nly View Post
    Ok, i got tired of having to flip the Spindle switch all the time and decided it was time to get Mach3 doing its job!

    I have a newer version of the Chinese CNC 3020T-DJ with a black controller box and the controller board is model JP-382A and the spindle board is JP-1482.

    The controller has a PWM output and the spindle board has a PWM input but they are not connected. Here is some pictures i included on another post..


    After i got done adding home switches to the controller i also started to trace out the boards to figure out the Spindle control.
    I just received my 3020T-DJ with the same controller box and powered it on for the first time. It looks like Mach3 is working correctly and I will be modifying the spindle on/off like you have described. Can you fill me in on adding the home switches? More specifically, how to do it and what do I need to add them? I plan on using this for engraving small plastic parts and wood. (kb0nly, it seems we may have gotten licensed the same year. I had a vanity license for a while and then went back to my original call sign)

  9. #29
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    Re: CNC 3020T-DJ Spindle Control, JP-382A JP-1482

    how are you measuring the spindle speed?

    sorry to resurrect a dead thread. I just got this machine.

    best P

  10. #30
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    Re: CNC 3020T-DJ Spindle Control, JP-382A JP-1482

    Hi Canislupus,

    At the moment, although I'm looking into this, there is no direct method of measuring spindle speed. In this case the board I built measures Mach3's PWM signal and adjusts the spindle motor speed accordingly. It's an imperfect solution, but so far nobody seems to have come up with a better method of providing software control with the JP-382A and JP-1482 boards. In practice it all seems to work well enough.

    Regards,

    Bob

  11. #31
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    Re: CNC 3020T-DJ Spindle Control, JP-382A JP-1482

    Do you think Id be able to implement your solution after changing the JP-382A to an Arduino Uno and a GRBL shield? This video is basically what im doing. the thing is, as of right now, I can isolate the two boards, in other words the arduino and steppers will be powered via the USB and this doesn't have to attach to the spindle chip at all. I checked this out by isolating the JP-1482 from the JP-382A and the spindle still works fine. Im not super familiar with electronics (I started this project to get some experience) but i think that the arduino has PWM stuff. Also, I plan to use universal g code uploader or something similar to run the steppers, so I really do have a lot of work ahead of me. Do you have any general tips? I can start a new thread and update it with progress if that would be more appropriate.

    Thanks!

    best P

  12. #32
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    Re: CNC 3020T-DJ Spindle Control, JP-382A JP-1482

    Quote Originally Posted by kb0cyl View Post
    I just received my 3020T-DJ with the same controller box and powered it on for the first time. It looks like Mach3 is working correctly and I will be modifying the spindle on/off like you have described. Can you fill me in on adding the home switches? More specifically, how to do it and what do I need to add them? I plan on using this for engraving small plastic parts and wood. (kb0nly, it seems we may have gotten licensed the same year. I had a vanity license for a while and then went back to my original call sign)
    I just saw posts to this thread in my email again while cleaning out my inbox, so sorry for the extremely long delay in getting back here, its been a crazy year with all the work i have taken on in my little shop.

    The limit switches are just basic micro switches that i added with some brackets i made up, nothing fancy. I can get some pictures of it if you wanted to see it. The way i set them up in Mach3 though is to use them as homing switches, So i can home all axis before a project. As for what you would need to add them, its just a few basic things, JST connector as mentioned back a page in this thread, then i used the same style microphone plug and panel mount jack to mount it up in the back panel. The wiring was what took the longest as i took the cable chains apart and routed the switch wiring with the existing wiring to make it all neat.

    I will have to get some pictures as it would far better explain what i did for them. Unless your worried about crashing it to a limit i wouldn't honestly bother with it, i thought it would be nice to have the homing switches but in the end i generally just zero the axis to the work i clamped down and hardly use the homing feature anymore. But then thats because 99% of the work i do on this machine is making PCB's, and i make an acrylic table thats bolted to the aluminum table with insets routed out for different size PCB blanks. So i just toss in a blank tape the corners down and then zero the engraving bit to the corner and away we go.

  13. #33
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    Re: CNC 3020T-DJ Spindle Control, JP-382A JP-1482

    Quote Originally Posted by canislupus View Post
    Do you think Id be able to implement your solution after changing the JP-382A to an Arduino Uno and a GRBL shield? This video is basically what im doing. the thing is, as of right now, I can isolate the two boards, in other words the arduino and steppers will be powered via the USB and this doesn't have to attach to the spindle chip at all. I checked this out by isolating the JP-1482 from the JP-382A and the spindle still works fine. Im not super familiar with electronics (I started this project to get some experience) but i think that the arduino has PWM stuff. Also, I plan to use universal g code uploader or something similar to run the steppers, so I really do have a lot of work ahead of me. Do you have any general tips? I can start a new thread and update it with progress if that would be more appropriate.

    Thanks!

    best P
    Sounds like you really took on a job there! I wouldnt know where to begin suggesting on that! I have very little Arduino experience. But i suspect as long as the Arduino can toggle the on and off like the original controller did there is no reason it couldn't. All it would take is an analog output from the Arduino to switch it.

  14. #34
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    Re: CNC 3020T-DJ Spindle Control, JP-382A JP-1482

    Hi All,

    Received my 3040 CNC with 800W VFD Motor few days ago. I Got X,Y,Z communication with Mach 3 software to work.

    Bad New: Mach 3 software is not able to turn on/off the spindle or control it. Or even give me a read out on the RPM.
    So far I can only control it manually from the inverter. The inverter gives me a Frequency Digital Display (Hz readout though that I can convert to RPM)

    Is there an easy fix to this (pin- port config) with out having to make hardware changes?

    My controller should be TB6560, but logo on controller says JD.. or HNE something something, see picture below

    Attachment 284520

    Thank you,
    Rob

  15. #35

    Re: CNC 3020T-DJ Spindle Control, JP-382A JP-1482

    kbOnly,

    I have found another way of turning the Spindle on and off without hacking the JP-382A at all.

    This is obviously if you have the low voltage issue, and do not intend on using the A Axis.

    I connected 5V pin from A Axis to Pin 4 of the Speed controller (4th from the left when looking from the front), then The PU (Pulse) pin from A Axis to Pin 3 of the Speed controller. I then placed a 1kOhm resistor between the two wires.

    I intend going an alternate route with my PWM speed control. I tried using the A Axis Direction Pin directly in place of the Potentiometer. As the Pot simply pulls a MCU pin to ground to speed up the Spindle it is limited to 5 V. Using A Axis output you have direct access to the Parallel port pins. Keep in mind there is no optical isolation. The Parallel port can not pull enough current to ground to slow the spindle to a crawl and only gives you speed control from around 70%-100%.

    I am going to build a small PWM switching signal through a Opto and Filtering (Maybe RC filter) that will essentially replace the POT.

    What are your thoughts.

    Great job on your mods, just trying to develop a simpler method.

  16. #36
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    Re: CNC 3020T-DJ Spindle Control, JP-382A JP-1482

    Quote Originally Posted by Mellbreak View Post
    Hi Canislupus,

    At the moment, although I'm looking into this, there is no direct method of measuring spindle speed. In this case the board I built measures Mach3's PWM signal and adjusts the spindle motor speed accordingly. It's an imperfect solution, but so far nobody seems to have come up with a better method of providing software control with the JP-382A and JP-1482 boards. In practice it all seems to work well enough.

    Regards,

    Bob
    I know this is an old thread, but have just got the controller (ha, the E-Stop button was loose- the flimsy plastic threaded piece had bust). Can't find much info about these boards, except for here. The 3020 user manual stated turning up the rheostat too quickly risks burning out the board, at best just blowing a fuse. Thing is, the photos in the manual were of the old style (blue) controllers so maybe it was just a problem with those. These do seem reasonably well built I think.

    Anyway, would it be possible to use the stepper board feedback signal to determine loading? It measures current through the 0.2R, which will be effected by spindle load.

    Has anyone tried changing logic on the unused mcu pins and see if that has an effect on the manual/auto pwm operation? Would think that the controllers that have software control, would also have a manual alternative.

  17. #37
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    Re: CNC 3020T-DJ Spindle Control, JP-382A JP-1482

    Quote Originally Posted by kb0nly View Post
    You need two JST-XH connectors to make the interconnect cable, also if you want to add limit/home switches its the same 4 pin JST-XH connector, look on eBay for LiPo balancing cables and connectors as they are used in the LiPo battery packs.

    Note... I don't yet have the PWM speed control working, still finishing up how to set that up, but i DO have Spindle On/Off control now from Mach3! The PWM control just wasn't as big of a concern for me as i generally run it full speed all the time for PCB milling.

    Ok, on the controller board the jack marked PWM i numbered them from the back panel forward, pins 1-4.

    1. LPT Port Pin #17 to Spindle Controller PWM Input
    2. +5v from Spindle Controller to the EL817 labeled DDO, This is Spindle On/Off
    3. Ground from Spindle Controller
    4. Spindle On/Off

    On the Spindle Controller board i labeled the pin numbers Left to Right looking at it from the front panel, pins 1-4.

    1. PWM
    2. +5v
    3. Ground
    4. Spindle On/Off

    The front panel Spindle switch only switches a ground on the Spindle Controller and its in parallel with an Optocoupler, part number EL817, on the Spindle Controller board. So you can leave the front panel switch for manual control and leave it in the OFF position to allow Mach3 to turn it on and off.

    You need to make a cable so that its matching 1-1, 2-2, 3-3, 4-4, using the pinouts as i described them. The plug orientation is flipped, so pin 1 on plug on one end of the cable would be the opposite side of the plug on the other end. You will understand what i mean when you look at the jacks, the controller board has its jack going front to back with the keyway to the left and pin 1 towards the back, but the spindle board has its jack going left to right and keyway to the back and pin one on the left. So the cable is a flipped crossover config.

    Set Mach3 for Active Low on Pin #1 to turn the Spindle On/Off.
    Set Mach3 to control the Spindle PWM using pin #17
    To sum it up. Is it enough to connect the PWM connectors and then you can drive spindle on / off?

  18. #38
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    Re: CNC 3020T-DJ Spindle Control, JP-382A JP-1482

    Don't know if anyone still following this but I have been doing a lot of reading of everything I can find on the web concerning controlling the spindle speed with software with the JP-1482A board. From what I have read this board using a micro controller for the PWM signal is not programmed for external software driving. I looked over the schematics from the PW3618 and the PW3024 boards. People say that they have made these boards operate by software by just connecting the PWM in and out between the two boards in the controller. By my feeble knowledge it looks to me like you could build the 555 timer portion of the circuit used on the 3618 or the 3024 board. Its just an opto isolator, a few resistors and caps and the 555 chip. Plug it into the PWM out from the JP-382A board and feed your new board into the gate of the mosfet driving the spindle motor using whatever method you like. Hopefully someone is still thinking about this also and has a comment.

  19. #39
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    Re: CNC 3020T-DJ Spindle Control, JP-382A JP-1482

    Quote Originally Posted by toppytop View Post
    Don't know if anyone still following this but I have been doing a lot of reading of everything I can find on the web concerning controlling the spindle speed with software with the JP-1482A board. From what I have read this board using a micro controller for the PWM signal is not programmed for external software driving. I looked over the schematics from the PW3618 and the PW3024 boards. People say that they have made these boards operate by software by just connecting the PWM in and out between the two boards in the controller. By my feeble knowledge it looks to me like you could build the 555 timer portion of the circuit used on the 3618 or the 3024 board. Its just an opto isolator, a few resistors and caps and the 555 chip. Plug it into the PWM out from the JP-382A board and feed your new board into the gate of the mosfet driving the spindle motor using whatever method you like. Hopefully someone is still thinking about this also and has a comment.
    That's the main problem. There appears to be descriptions of ideas or methods associated with modifications to achieve spindle control via software (eg. Mach 3 control). But the described methods never appear to be complete or clear. Eg. " connecting the PWM in and out between the two boards in the controller" isn't very clear. Also, "build the 555 timer portion". What 555 timer? What's that used for?

    At the moment, I'm trying to achieve the same thing..... spindle control using software (such as Mach 3), instead of always needing to turn the dial on the black coloured China CNC controller box. I don't know much about the boards in that controller box right now, since I'm new to this. However, I assume that when we turn the physical speed control dial clockwise, this action will vary a DC voltage (somewhere inside the China CNC controller box) for which to rotate the spindle, right? Or, that varied DC voltage is used to generate a PWM signal (with adequate power handling) to energise the spindle. So, if we are able to disconnect that particular internal DC or PWM signal (which means removing the physical dial speed-control functionality), and put in our own hardware module as a middle-man, then we could then have a way of controlling the spindle speed via software.

    It appears that people have successfully achieved software-controlled spindle operation, but they all have their own way - due to the various kinds of software and hardware available. What I'm interested in is .....a method to make minimal modifications to the stock China CNC black-coloured controller box in order to achieve spindle control (via software - preferably Mach 3).

    This person at the following link appears to have done some very nice work in figuring out various details of China CNC controllers.

    https://hackaday.io/project/6776/logs

    But...... once again... some inconsistencies in details. Eg.... it mentions that the China CNC spindle dial involves a resistive divider, consisting of 6K resistance, with one end of that 6K resistance connected to "3.3 V".....while their hand-drawn circuit diagram indicates that end is connected to 5 Volt DC, instead of '3.3V'. And then it says the mid-point of the resistive divider has a 5K rheostat (in the form of a potentiometer) connected to it, and the other end of the rheostat goes to ground. However, the details indicate that the 'maximum resistance' of the rheostat is 3.3K, which doesn't make sense when they're initially indicating a 5K rheostat. Confusing.

  20. #40
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    Re: CNC 3020T-DJ Spindle Control, JP-382A JP-1482

    Quote Originally Posted by SouthPark View Post
    This person at the following link appears to have done some very nice work in figuring out various details of China CNC controllers.

    https://hackaday.io/project/6776/logs

    But...... once again... some inconsistencies in details. Eg.... it mentions that the China CNC spindle dial involves a resistive divider, consisting of 6K resistance, with one end of that 6K resistance connected to "3.3 V".....while their hand-drawn circuit diagram indicates that end is connected to 5 Volt DC, instead of '3.3V'. And then it says the mid-point of the resistive divider has a 5K rheostat (in the form of a potentiometer) connected to it, and the other end of the rheostat goes to ground. However, the details indicate that the 'maximum resistance' of the rheostat is 3.3K, which doesn't make sense when they're initially indicating a 5K rheostat. Confusing.
    Update: After some tinkering of my 3040Z-DQ, I found out (from internet searches) that the Mach 3 software can indeed be used to produce a PWM signal signal from a parallel port pin of a desktop computer. I used windows xp (as Mach 3 recommends XP or Win 2000, which are 32 bit operating systems). Apparently Mach 3 has issues with controlling the parallel port when 64 bit operating systems are used. Need to go to 32 bit systems. I followed a youtube video for making pin 17 of the parallel port produce PWM.

    https://www.youtube.com/watch?v=P3CNtyOVHNc

    After checking things out, I discovered that the most important things include:

    1) Mach 3 configuration of the spindle PWM output pin is performed in the 'motor output' section, in the configuration row for the 'Spindle'. And this PWM output pin will relate to the "STEP" pin. Yes, relates to the "STEP" pin. Yes, we know that "PWM" has got absolutely nothing to do with stepper motor "steps" (since spindle motors are usually not stepper motors), but these are the 'rules' that the Mach 3 software writers created themselves, however ridiculous and confusing it is. Anyway, in the 'Spindle' row settings, a tick/checkmark is needed to ENABLE the spindle, and the "STEP" pin number (which is the parallel port pin number we want to produce the PWM signal) is to be set to 17.

    So the 'Spindle' row settings should be:

    TICK - 17 - 0 - CROSS - CROSS - 1 - 0. And, in the Spindle Setup page, under 'Motor Control', put a tick/check mark for the "Use spindle control" box, and also put a tick/check mark for the "PWM control" box, and also set PWMbasefrequency to "250"

    The settings for output#1, output#2 etc are unnecessary for PWM generation. So, no need to deal with output#1, output#2 etc. I'm just focusing on the essentials for getting a PWM signal to show up on a parallel port pin.

    2) Then, massively important, is to finally go to the Mach 3 front control panel, and focus on the SPINDLE SPEED control panel, which is the box that has the software BUTTON that says 'Spindle CW F5". Here, it's necessary to use the mouse to push this button in order to activate it. Activated mode will mean yellow edges on this button. And secondly (massively important), is to click on the purple box to manually set a Spindle Speed. For example, the purple box might initially have '0'. So, it's necessary to use the mouse to click on that value (such as click on the '0' with the purple box around it), and then manually type in something like a value of '100' (then hit enter). Once we've manually entered a value, the PWM pin we selected (such as pin 17) will spring to life. And we can then use the mouse to increase or decrease the PWM duty cycle with those software up/down arrow buttons directly underneath the "Spindle CW F5" button.

    I'm writing the above, since I noticed that leaving out some very tiny thing can put us in a 'so close, but yet so far' situation in terms of trying to achieve something that is meant to be simple to do.

    Also, for the spindle "PULLEY" configuration, I just configured Pulley Number 1 with Min Speed = 0, Max Speed = 100, ratio = 1.

    Anyway, what I need to do now is to just make use of the PWM signal. At least the software allows us to generate PWM.

    Now, how could we use the PWM? I'm thinking.....the mid-point of the voltage divider (of the CHINA CNC controller's physical potentiometer) is currently used in the China CNC controller for providing a DC control voltage. So, instead of using the potentiometer for producing the DC control voltage, it should (instead) be possible to make our own control DC voltage by using an "R-C filtered" version of the parallel port's PWM signal. From multimeter measurements on the PWM pin of the parallel port, I found that 100% duty cycle, which translates to a plain DC voltage, corresponds to 3.3 Volt.

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