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IndustryArena Forum > CNC Electronics > Stepper Motors / Drives > parallel to usb? + can i "convert" open loop to closed loop steppers?
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  1. #1
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    parallel to usb? + can i "convert" open loop to closed loop steppers?

    Hey there a couple of questions:



    • 1: parallel ports seems a bit out of date, although I've already got "all" the electronics for a CNC mill (3 or 4 axis) - can I buy something so that I can connect to PC with USB or do I need to buy all new electronics? (I've got a Leadshine Mx3660 + another cheapo breakout board)




    • 2: I've bought a lot of CNC building stuff, but back when I got it I didn't actually know which way to go so I've got regular open loop Nema 23 + 34 steppers. - is there any encoders that can be attached to the motors so that I can convert them to closed loop steppers or do I need all new closed loop steppers? ( I ofcause also need somekind of encoder input that can connect to Mach3)




    • 3: I'm guessing closed loop steppers are the easiest/ cheapest way of minimizing the loss of steps/ improve precission - am I right or is there better ways - let me hear your thoughts on this



    I'm a student so I'm looking for a satisfying solution on a budget!
    (I'm pretty good at the hardware/ machining part, but when it comes to electronics/ software I need some guidance )

    -kind regards Teglberg
    (Denmark)

  2. #2
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    Re: parallel to usb? + can i "convert" open loop to closed loop steppers?

    1. UC100, UC300, UC400 and Smooth stepper are some of the options. Google and look them up. I am a happy user of UC300.

    2. and 3. Why close loop? If you have accuracy problems you should solve them, not hide them.

  3. #3
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    Re: parallel to usb? + can i "convert" open loop to closed loop steppers?

    1: I've been looking at those, think I'll go with that then (just to be 100% clear, it's: PC>USB>UC300>stepper controllers>stepper motors right?)
    2 and 3: it was just to be sure, do you recommend open loop/ do you think closed loop is excessive/ unneeded then?

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    Re: parallel to usb? + can i "convert" open loop to closed loop steppers?

    Quote Originally Posted by teglberg View Post
    1: I've been looking at those, think I'll go with that then (just to be 100% clear, it's: PC>USB>UC300>stepper controllers>stepper motors right?)
    PC>USB>UC300>BoB>stepper controllers>stepper motors

    The BoB is necessary, just like with parallel port use. It provides optical isolation.

    Quote Originally Posted by teglberg View Post
    2 and 3: it was just to be sure, do you recommend open loop/ do you think closed loop is excessive/ unneeded then?
    Just steppers. No need for feedback to Mach3, the accuracy should normally be very high anyway, and like I said, if you have missing/extra steps or other issues, you should fix those and not hide them. You are on a tight budget, and here you can save money. Spend the money on good power supply and stepper drivers, not on encoders and closed loop systems. That may be necessary for a very high speed professional machine, but for hobby use... on tight budget...

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    Re: parallel to usb? + can i "convert" open loop to closed loop steppers?

    Thanks your advice is greatly appreciated!

    - if you don't mind I have another question besides the original post:

    do you have any experience on spindle selection (main spindle - the one that does the cutting) I was considereing using a Nema34, do you think it could work? don't know if it's strong enough, I would like to have the ability too cut steel (maybe just small chips to minimize the pressure). Also if I use a Nema34 i might get the ability to index the spindle?

    thanks again!

  6. #6
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    Re: parallel to usb? + can i "convert" open loop to closed loop steppers?

    If you are on a tight budget, then why not stick with a parallel port? I run my milling machine on a surplus pc I got for free using linuxcnc. Linuxcnc is free as well. It works great too.

    So let's look at what it costs just so you can use USB and Mach 3/4. A uc100 is $120, mach3 is $175. Or mach4 is $200. So you are talking about $300 so you can use Mach and a USB.

    Parallel ports may be out of date, but they work just fine.

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    Re: parallel to usb? + can i "convert" open loop to closed loop steppers?

    Mesa has some inexpensive solutions for linuxcnc. For $89 they have in effect 2 printer ports if i/o and very expandible.

    http://mesaus.com/index.php?route=pr...&product_id=51

    Or

    7i92

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    Re: parallel to usb? + can i "convert" open loop to closed loop steppers?

    The pulses timing with a UC100 is much better than with a parallel port. https://www.youtube.com/watch?v=1m3ixFcjgVo
    You get more reliable motion, higher possible feeds etc.
    With UC100 you can also use the UCCNC which again gives you better motion than Mach3 and is much cheaper, $60 only.

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    Re: parallel to usb? + can i "convert" open loop to closed loop steppers?

    Quote Originally Posted by OlfCNC View Post
    The pulses timing with a UC100 is much better than with a parallel port.

    You get more reliable motion, higher possible feeds etc.
    With UC100 you can also use the UCCNC which again gives you better motion than Mach3 and is much cheaper, $60 only.
    Much better than mach3 through a parallel port. I don't doubt that since mach3 is running on Windows which is not a real time OS.

    Linuxcnc runs on a specially prepared realtime version of Linux, so the same may not be true of Linuxcnc

    In any case, there are many many many people running cnc machines on parallel port successfully. For a budget build there is no cheaper way.

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    Re: parallel to usb? + can i "convert" open loop to closed loop steppers?

    I said "with UC100 you can also use the UCCNC which gives you better motion", please reread and interpret my post again, I did not talk about LPT ports ... they are dying out dinasours.

  11. #11
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    Quote Originally Posted by 109jb View Post
    If you are on a tight budget, then why not stick with a parallel port? I run my milling machine on a surplus pc I got for free using linuxcnc. Linuxcnc is free as well. It works great too.

    So let's look at what it costs just so you can use USB and Mach 3/4. A uc100 is $120, mach3 is $175. Or mach4 is $200. So you are talking about $300 so you can use Mach and a USB.

    Parallel ports may be out of date, but they work just fine.
    I'm also tight on space so would like to use laptop + I don't want to be stuck on one specific PC would like to change sometimes so that I can program on the go but mostly just for comfort, it's annoying to build something new that's "old" already guess it's a matter of preference

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    Re: parallel to usb? + can i "convert" open loop to closed loop steppers?

    Depending on your preference, you could also use a microcontroller solution. I also use GRBL on an Arduino and it works quite well, but has limitations. The way it operates is that the GRBL/Arduino actually performs all of the realtime functions and has the g-code interpreter built in. It has a basic set of G-code commands that includes the most common commands. There are CAM postprocessors for it, so you can do pretty much everything in CAM anyway. The PC used doesn't have to be anything special and there are many GUI interfaces for GRBL. This is also a very inexpensive solution. All of the software/firmware is free and the Arduino can be bought in clone form for about $5. The arduino replaces the breakout board and wires directly to the stepper drivers. It is not as full featured as LinuxCNC or MAch3, but can do a bunch. I like to tinker, so I am really enjoying GRBL by writing my own interface in VB to suit my own needs. That said there are many interfaces that are simply download, install, and go.

    If interested, here is some information.

    First is my mill running a comparison between LinxuCNC and GRBL with the same g-code. This is an older version of LinuxCNC, so GRBL and LinuxCNC run about the same speed now.
    https://youtu.be/c1mxS7WI-tg

    Here is the GRBL site on github
    https://github.com/grbl/grbl

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    Re: parallel to usb? + can i "convert" open loop to closed loop steppers?

    Quote Originally Posted by OlfCNC View Post
    I said "with UC100 you can also use the UCCNC which gives you better motion", please reread and interpret my post again, I did not talk about LPT ports ... they are dying out dinasours.
    Well lets just see what I interpreted. In your post #8 you said:

    Quote Originally Posted by OlfCNC View Post
    The pulses timing with a UC100 is much better than with a parallel port.
    That opening sentence said nothing about the UCNC at all. Was I supposed to read your mind?

    Quote Originally Posted by OlfCNC View Post
    You get more reliable motion, higher possible feeds etc.
    Again, no mention of UCNC. These first 2 sentences say that with the UC100 the timing is much better. Didn't say with what software on the PC.

    Quote Originally Posted by OlfCNC View Post
    With UC100 you can also use the UCCNC which again gives you better motion than Mach3 and is much cheaper, $60 only.
    Finally you mention UCNC,.

    So what exactly did I misinterpret? I should read from the bottom up I guess.

    I think you should re-read your post and see what you said before spouting off and lecturing.

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    Re: parallel to usb? + can i "convert" open loop to closed loop steppers?

    Also your post simply said the pulses timing with a UC100 is much better than with a parallel port, but did you compare to Mach3 through a parallel port only, or did you compare to LinuxCNC running through a parallel port as well? That was the point I was making.

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    Re: parallel to usb? + can i "convert" open loop to closed loop steppers?

    Quote Originally Posted by 109jb View Post
    Also your post simply said the pulses timing with a UC100 is much better than with a parallel port, but did you compare to Mach3 through a parallel port only, or did you compare to LinuxCNC running through a parallel port as well? That was the point I was making.
    Both.

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    Re: parallel to usb? + can i "convert" open loop to closed loop steppers?

    OK, let's see my post again you quoted:

    The pulses timing with a UC100 is much better than with a parallel port.

    You get more reliable motion, higher possible feeds etc.
    With UC100 you can also use the UCCNC which again gives you better motion than Mach3 and is much cheaper, $60 only.
    In the first sentence I wrote that the pulse timing is better with a UC100 than with a parallel port.
    I stated nothing more nothing less.
    So you do not have to read my mind since I was not talking about any software, just about pulse timings coming from a LPT port and a UC100.
    I did not mention what software, what operating system or anything else.
    I think it should be clear that there is no operating system on the world which could generate better timed pulses even as close reliably as what a lower level device an FPGA or microcontroller can do.

    The next sentence is a conclusion of what he can benefit from a better timed pulse stream.
    And again it does not matter what software or what device, I was still only talking about the quality of pulses timing, no more, no less.

    And in the final sentance I've mentioning that with the uccnc you get a better motion than from Mach3 which statement is simply based on my experience.

  17. #17
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    Re: parallel to usb? + can i "convert" open loop to closed loop steppers?

    Also, Mach3's parallel port output quality can vary greatly from PC to PC. With some PC's, you may not see a noticeable difference from parallel port to UC100. With other PC's, it might be a world of difference.
    Gerry

    UCCNC 2017 Screenset
    http://www.thecncwoodworker.com/2017.html

    Mach3 2010 Screenset
    http://www.thecncwoodworker.com/2010.html

    JointCAM - CNC Dovetails & Box Joints
    http://www.g-forcecnc.com/jointcam.html

    (Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)

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    Re: parallel to usb? + can i "convert" open loop to closed loop steppers?

    Quote Originally Posted by 109jb View Post
    Much better than mach3 through a parallel port. I don't doubt that since mach3 is running on Windows which is not a real time OS.

    Linuxcnc runs on a specially prepared realtime version of Linux, so the same may not be true of Linuxcnc

    In any case, there are many many many people running cnc machines on parallel port successfully. For a budget build there is no cheaper way.
    Yes, there is a cheaper way, and that is the UC100 way. Why buy a dinosaur PC, go through the troubles of using parallel port when for an additional $60 you can use the PC you most probably already have? Apart from that, if you have an old PC you can still use that with the UC100 because it is definitely MUCH better than using a parallel port, just like OlfCNC is saying.

    But sure, on a very tight budget a free (or almost free) PC with a free software and a free OS is better than a commercial software like Mach3 and Windows10. The disadvantage is that with no Linux experience life can be a PITA with LinuxCNC.

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    Re: parallel to usb? + can i "convert" open loop to closed loop steppers?

    Good options all around. I'd just like to add that even with optical isolation, I would be wary of using my main PC to drive a mill. Better to use an old laptop, or a Rasberry Pi, or even just an Arduino with an SD card and LCD / switches user interface. I personally like using an old DOS PC with TurboCNC via the parallel port, but that's just me... when something works, I tend not to change it. And honestly, my test bed CNC machine isn't anything to look at. It's always torn up testing new drivers or whatever. I do also use a RAMPS/Marlin motion controller (Arduino based) but I feed the G-CODE from an old laptop. No optical isolation... so far so good... and if it does fry, that machine cost like $50. I should probably switch to my RasPi... since that cost $25.
    James hosts the single best wiki page about steppers for CNC hobbyists on the net:
    http://www.piclist.com/techref/io/steppers.htm Disagree? Tell him what's missing! ,o)

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    Re: parallel to usb? + can i "convert" open loop to closed loop steppers?

    and if it does fry, that machine cost like $50. I should probably switch to my RasPi... since that cost $25.
    My issue is that my workpieces often cost more than that, so if the system fries costs me more than the PC.

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