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Taking the CNC Plunge

Discussion in 'PRECISION-MATTHEWS' started by TomS, Aug 6, 2014.

  1. TomS

    TomS Active User H-M Supporter-Premium

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    Well, I've done it now! I ordered a PM-932M for a CNC conversion. Thank you Ray C. for working with me during the sales process. I've been in the machining business my entire career so I've got the background in manual machining but have no experience with CNC. The learning curve will be with the electronics, associated software, and CAD. Been reading about conversions and I've decided to approach it in the same manner as jumps4 (Steve) did with his conversion, e.g. direct drive, 1600 oz in motors for X and Y, 4200 oz in motor for Z, one shot lube system, and Chinese control/drive electronics. I'm going to start with the mechanical conversion phase first and save the electronics for last. My thought is that the control side will be fresh in my mind when it comes time to start up and trouble shoot. Of course I'm going to lean on all of you for your insight as I move through the conversion. It will be challenging but I'm up for it. Can't wait to get started.
    :rubbinghands:

    Tom S
     
  2. dave2176

    dave2176 United States Active User Active Member

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    Somewhere on here another member did a great job on a cnc 932 conversion. I think it was jbolt but I couldn't find it. Maybe somebody has the link to the thread. Please keep us updated as you proceed.
    Dave
     
  3. TomS

    TomS Active User H-M Supporter-Premium

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    Just found the thread you mentioned. It's in the CNC in the Home Shop forum. You are correct it was jbolt.

    Tom S
     
  4. countryguy

    countryguy United States Active User Active Member

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    1st- All the best! you'll manage just fine. I went from zip to 110mph and it's all good! Never stop learning and taking new journeys! Congrats on that.
    Mind if I ask what package constitutes the Chinese control / drive eletronics? Just curious - So many use the G540 3 or 4 axis w/ Mach3. But I'm new as well, so was curious what type of package for the Mill you were looking upon. And will it be Mach3 driven w/ Windows or Linux? Dare I ask Mack4? ;-)
     
  5. TomS

    TomS Active User H-M Supporter-Premium

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    The electronics package I'm looking at is an Ebay item - 3 Axis CNC 1600 OZ-IN & 4200 OZ-IN Spindle Stepper Motor 3D Printer 110BYGH201-001 sold by Wantai Motors. Comes with the following:
    2 PCS Nema 34 Stepper Motor with Single shaft 1600 oz-in holding torque,
    1 PC Nema 42 Stepper Motor with Single shaft 3256 oz-in Holding torque,
    2 PCS Stepper Driver DQ860MA with 7.8A replacing MD882,
    1 PC Stepper Driver DQ2272 With 8.0A Peak current, 7.0A rated current, 110-220 VAC, 200 Microstep,
    2 PCS Power Supply for 350w, 60 VDC, 5.9A,
    1PCBreakout Board,
    1 PC DB25 Cable

    What do you think? Again, I'm not electric/electronic literate but anxious to learn.

    I'm planning on a Windows 7 platform running Mach 3. Could be Mach 4 but I need to find out what the differences are before making a decision.

    Thanks for your interest.

    Tom S




     
  6. JimDawson

    JimDawson Global Moderator Staff Member Director

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    Looks like it would work. Their specifications don't seem the match the title, but that is just the ad copy I suppose, not being too careful with the wording.

    Sounds like a fun project. I wasn't too impressed with Mach 3, but I was trying to use it on a high speed industrial router. It did seem to work for slower speed applications. It will be interesting to see how Mach 4 performs if it ever gets released.

    You might search the other posts on this forum to see what some of the other folks have done. The good news is that you came to the right place, there is always someone willing to answer your questions.
     
  7. TomS

    TomS Active User H-M Supporter-Premium

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    Thanks Jim. The electronics are all new to me. I'm sure I'll have lot's of questions.

    Tom S
     
  8. TomS

    TomS Active User H-M Supporter-Premium

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    My mill arrived today!!! Spent the better half of the day uncrating and cleaning. Once I get it on the stand I'll do a run in on the headstock gears and check out the other systems to make sure everything works. But wouldn't you know it, the local Harbor Freight is out of stock on 2 ton engine lifts. Will have to wait until Monday for the next shipment. First step in the CNC conversion will be installation of a one-shot lube system. Here's a few pieces of eye candy for your viewing pleasure.

    Tom S

    photo 11.jpg photo 12.jpg photo 13.jpg photo 14.jpg photo 5.jpg

    photo 11.jpg photo 12.jpg photo 13.jpg photo 14.jpg photo 5.jpg
     
  9. GA Gyro

    GA Gyro H-M Supporter - Premium Content H-M Supporter-Premium

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    Does yours have the power down feed and 3PH motor?

    Was looking at the pics... the X drive unit is obvious... what is that black drive unit in the wood box at the back of the column?
    THX
     
  10. wrmiller

    wrmiller Chief Tinkerer H-M Supporter-Premium

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    Z-axis drive.
     
  11. chuckorlando

    chuckorlando Active Member Active Member

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    Looks good. If you dont mind me asking... How much money do you guys have in one of these conversions? You would need something like the kit linked and then ball screws? Anything else besides a PC?
     
  12. TomS

    TomS Active User H-M Supporter-Premium

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    I didn't get the PDF option because I'm converting to CNC. The motor is single phase 120/220 volt AC. A three phase motor and VFD is something that I may do after I'm up and running.

    I did a trial run in each of the speed ranges after changing out the headstock oil. I was pleasantly surprised at how quiet it was. The three axis' were smooth through their full travel. I checked the spindle taper run out with a .0005" DTI and the needle barely moved. Overall the machine appears to be good quality.

    Tom S
     
  13. TomS

    TomS Active User H-M Supporter-Premium

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    I've done a lot of reading on other CNC builds to get a feel for what it takes in the way of materials and effort. For me the mechanical part of the conversion is not that difficult, it's the electrical/electronic areas where I'm weak. So I could get my arms around the material requirements I put together a BOM. The big dollar items are the mill, motors and electronics, ballscrews and nuts. A PC is required but not that expensive. It's the CAD and CAM software that can run into some dollars. You still need to gather the miscellaneous electronics (relays, breakers, switches, wire, etc.), a box to put it in, and motor mount materials, plus other miscellaneous items. By my estimation I'm going to have about $5,500 in it by the time I'm through. Some have spent less and some more.

    I hope I've answered your question. If not let me know and I'll share the details.

    Tom S
     
  14. zmotorsports

    zmotorsports United States H-M Supporter - Premium Content Staff Member H-M Supporter-Premium

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    Looks great. Congrats on the mill and sounds like you have a solid plan for the CNC conversion.

    Mike.
     
  15. chuckorlando

    chuckorlando Active Member Active Member

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    Thanks for your time. How much of that is just in the conversion? It would cost an arm and leg to cnc my bridgeport so if I went that route it would be on a smaller newer machine or an older already cnc factory job. Just wondering what one might expect to pay minus the mill and cad/cam.
     
  16. TomS

    TomS Active User H-M Supporter-Premium

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    Minus the mill and CAD/CAM expect to spend $2,000-$2,500 for a ZX45 conversion.

    Tom S
     
  17. GA Gyro

    GA Gyro H-M Supporter - Premium Content H-M Supporter-Premium

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    Just curious here...

    When folks CNC a '45'... is it still possible to use it manually... or is it either/or?

    Seems there would be times where hands on was easier than setting up a program to do something simple.

    Obviously a noob question... however one has to learn... :)
     
  18. JimDawson

    JimDawson Global Moderator Staff Member Director

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    Apologies to TomS. We are kind of hijacking this thread, but I think this a very pertinent question.

    The most common and least cost conversion uses stepper motors that are either direct or timing belt coupled to the lead screws. With the stepper motor powered down, it is possible to overpower the inherent mechanical (magnetic) resistance of the stepper motor manually. It takes a fair amount of force to do so and the stepper motors cog due to their design. Assuming that you are using a standard 200 step/rev motor and have a 5 pitch lead screw that is direct coupled, then the motor will cog at 0.001 inch increments. Irritating at best on the X and Y axis. On the Z axis, without decoupling the quill from the lead screw, it is impossible to use the quill manually. Without providing a very convenient way of decoupling the stepper motors from the lead screws, manual operation is not very practical. If I couldn't switch over in under a minute, I would find it very irritating.

    Another and more costly option is to use DC servo motors. These have almost no mechanical resistance when powered down. The Z axis lead screw still must be decoupled from the quill to manually operate the quill. The down side of this is the cost and the more complex control system.
     
  19. TomS

    TomS Active User H-M Supporter-Premium

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    Jim - no need to apologize. I'm a CNC newbie too and looking for as much information as others will offer up. My build will be a learning experience as I don't have any prior CNC exposure and I'm real weak when it comes to the electrical/electronics side of the conversion. Anyway should be a fun project.

    Tom S
     
  20. jbolt

    jbolt United States Active User H-M Supporter-Premium

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    Just to add, on a 45 clone the Z can be driven by the head or quill. Driving the head allows for more useful cnc head travel and leaves the quill free to use manually. On that note I did a power down feed on my smithy quill using a stepper driving the fine feed worm. I can use the fine feed manually when not powered but if it is turned too fast the stepper will lock which would be extremely annoying in the X Y of a mill table.

    I did not bother trying to make my PM932 cnc conversion usable manually. The few manual operations I have needed to do are easy enough using the MDI interface or pendant.

    Jay
     
  21. chuckorlando

    chuckorlando Active Member Active Member

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    Most cnc's can be run "manual" through the comp if I am not mistaken
     
  22. maker of things

    maker of things United States Hermit H-M Supporter-Premium

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    I can turn the power to the stepper off and manually mill with my G0704 no problem. However, it is much easier for me to use the MDI (Manual Data Input) to use the mill like a programmable power feed. Say you need to mill a slot. Align the cutter as you would manually just use the arrow keys or pendant to jog the cutter and set your zeros. switch to the MDI screen (Mach3) type g00z-.03 (enter) <enter> z rapids to -.03" doc. Type g01x2.5f.5 (enter)<enter> the mill will move the table 2.5 inches at .5 ipm. You can do a lot of one off work by just typing one line at a time. If you need to repeat a command, at the MDI line hit the up arrow to scroll up to the code you want to reuse and (enter) <enter>.

    I would also suggest reading Jumps4 thread, he converts a 45 class mill. http://www.hobby-machinist.com/showthread.php?t=8187 its a few pages back.</enter></enter></enter>
     
  23. TomS

    TomS Active User H-M Supporter-Premium

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    I've read Jumps4 thread several times. Lot's of valuable information there. His thread also has a link to an X2 conversion that walks through the wiring details. Jbolt has a thread on his PM-932 conversion that is also very helpful. For those of us that don't have a strong background in CNC these are an excellent source of information. Steve (Jumps4) and Jay (Jbolt) have offered to help me through my conversion. A couple of stand-up guys.

    Tom S
     
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  24. GA Gyro

    GA Gyro H-M Supporter - Premium Content H-M Supporter-Premium

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    Just curios...

    Has anyone done a CNC to a knee mill?

    Both Jump and Jbolt's threads are good reads... need to go through them again.

    Being new to hobby machining (have some shop experience from decades ago), I probably will use the machines manually for a while... then do the CNC conversion on the mill.

    Does anyone have the link to Jump's lathe CNC conversion? THX
     
  25. TomS

    TomS Active User H-M Supporter-Premium

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    Here's the link - file:///C:/Users/Tom/Documents/Machining%20Related/CNC%20Conversion%20Info/RF-45%20ZX-45%20CNC%20Converstion%20by%20jumps4.htm

    Tom S

    Edit - My bad! I posted the link to my file location. Here's the correct link - http://www.hobby-machinist.com/showthread.php?t=8187&highlight=cnc+conversion
     
  26. GA Gyro

    GA Gyro H-M Supporter - Premium Content H-M Supporter-Premium

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    Read through Jump's MILL conversion thread....

    Would like to read Jump's LATHE conversion thread... Does anyone have the link to the LATHE thread... THX!

    (Sorry for the repeat question... I have posted the wrong link many a time myself... :) )
     
  27. awander

    awander United States Active User Active Member

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    Those motors' torque ratings are crazy. They will be very slow. You would most likely get much better performance by using smaller motors with belt drives.

    Also, what are the other specs on the motors? Voltage, current and inductance?

    What about the drives, what is their max voltage?

    I wouldn't be surprised of the kit components are not well matched to each other.
     
  28. TomS

    TomS Active User H-M Supporter-Premium

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    Here's the link to the lathe conversions - http://www.hobby-machinist.com/showthread.php?t=8692

    Tom S
     
  29. TomS

    TomS Active User H-M Supporter-Premium

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    1600 oz-in motor specs - 5.7V/3.5A, 22mH/phase

    4200 oz-in motor specs - 5.36VDC/8.0A, 12mH/phase

    The DQ880MA driver is rated at 80VDC. The DQ2722M is a combined driver/power supply. The driver output voltage is not listed in the eBay ad so I'll have to do some digging. Steve used the same motors and drivers for his conversion and made a reference to being able to machine at up to 200 in/min. The intent of the conversion is for me to learn about CNC. I'm certain it will have adequate speed butiIf it runs slower than a production based machine I'm not concerned.

    Tom S.
     
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  30. JimDawson

    JimDawson Global Moderator Staff Member Director

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    Just to put things in perspective. I did a controls upgrade on a commercial 4x8 foot CNC router, with a 12HP spindle motor, and retro-fitted it with NEMA 34, 1200 oz/in stepper motors. The original motors were 400 oz/in DC servo motors. It is common practice to oversize the steppers to try to prevent de-coupling under load.

    The reason for the upgrade was the old computer died and a replacement was not available. The customer also wanted to run Mach3 on the machine, and it is difficult to use Mach3 to drive an analog (the DC motor controllers) control system. So we went with stepper motors and a parallel breakout board from ebay. The stepper motors and drivers for this project were purchased from Automation Direct at about double the cost of the system from Wantai, but they are a known quantity. I built my own 80V, 500 watt power supply to run the system.

    The 5 pitch lead screws are driven by timing belts that are geared down by a ratio of 1.3:1 on the X and Y axis and 3:1 on the Z. Normal cutting speeds are in the range of 150 IPM, with rapids at 300 IPM. It will rapid at about 600 IPM, but that is frightening and starts getting a bit squirrely, so it is limited. Z moves are limited to about 60 IPM rapid, and normal plunging speed is in the 20 IPM range. It is set up to run 20,000 micro steps/revolution so things operate very smooth.

    Mach3 will not run the router at these speeds due to the limitations of the pulse train generator in the software, so we changed the motion controller and software to a much higher speed, and considerably more expensive system. Mach3 will work OK for slower speed systems like milling machines, plasma cutters, and table top routers.

    The point of this is that in metal machining you will never run speeds anywhere close to the maximum stepper motor speeds so that is not really a factor in determining what stepper motors to use, but more torque = good. The torque curve of stepper motors is almost flat until you hit the motor's mid speed range, then it starts dropping off. Most of my metal machining is done in the <20 IPM range, with maximum rapids at 100 IPM.

    In general, maximum stepper motor speed is a function of available voltage. The motor current is limited by the drive, but the voltage really controls the pulse rise time and therefore the motor speed. The highest voltage rated stepper driver I have seen is 80V.

    This is not an endorsement, but assuming that the Wantai motors and controllers perform as advertised, I would say that they will have plenty of power and speed for a milling machine or lathe CNC conversion.
     
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