Mini Engraver

Discussion in 'The Projects Forum' started by R!f@@, Feb 25, 2010.

  1. R!f@@

    Thread Starter AAC Fanatic!

    Apr 2, 2009
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    Above is the thread starter.
    From now on this thread will be updated as this project progresses

    Hi BMorse
    I am posting the pictures without finding their capacity as per your request, and since my buddy is back and I got the cam, I thought I'll start by posting the pics of all the motors I have.As per forum member request I will be making this engraver via this thread and every one please feel free to comment.
    As BMorse requested here are the pictures of the motors that I currently have.
    [​IMG]

    This is the dremmel that I use for now. I will post the specs separately.

    [​IMG]

    This is a DC motor and runs around 48V I think, I did tried it once using 24VDC. It has plenty of torque and RPM. I have to measure the RPM later.

    [​IMG]

    Above is the motor that I was talking about, the lazer disc drive motors, it has a high rpm and runs on around 24VDC. I remember this having a good torque. I have to recheck, if you like.

    [​IMG]

    This one was salvaged from a xerox machine. Haven't tried to run it yet.

    [​IMG]

    This is also a DC motor, could not check it since a bloody rat has chewed of the cables all the way. I have to dismantle and rewire it.

    [​IMG]





    These are as you know printer steppers.


     
  2. R!f@@

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    Apr 2, 2009
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    and more
    [​IMG]
    [​IMG]
    Below are the capacitors that I have been storing for years.
    I donno what to do with them, I cannot just throw em' u know.
    I was thinking of making a DC spot welder thingy. :D
    [​IMG][​IMG]
    [​IMG]
    what do you think?
     
    Last edited: Feb 25, 2010
  3. jpanhalt

    AAC Fanatic!

    Jan 18, 2008
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    As for the spot welder, add up the total capacitance you would have. Capacitor discharge type of welders probably need at least 0.3 F to be effective at voltages of 30V or less. I would not recommend going to higher voltage, mainly because of the great shock hazard. Even 30 volts is not completely safe from shock. So, your design should consider a maximum voltage of 24V or so.

    Second, very old electrolytic capacitors will need to be conditioned first.

    John
     
  4. R!f@@

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    Enlighten me
     
  5. jpanhalt

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  6. R!f@@

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    Bloooody hell!!! :confused:
    where the hell was I in those days.
    450V caps...c'mon jeeeeeeeeeeeeeez. Now I need a 500V PSU.
    Doggon it!!!!
    And you john, waited so long to tell me these .....
     
  7. SgtWookie

    Expert

    Jul 17, 2007
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    You don't necessarily have to charge those caps all the way to their rated voltage, but you should charge them (using a current limited source, like a 10k resistor) to at least twice the maximum voltage that you will be using.

    Don't forget that a charged capacitor needs to be discharged safely. If you simply short the cap terminals, you may damage the capacitor and/or the device used to short the terminals. If you connect a 10k resistor to the + cap terminal and the COM terminal of a SPDT switch, you can connect one of the switched terminals to the - cap terminal (to discharge the cap) and the other switched terminal to the + voltage supply. Then just connect the - voltage supply to the - side of the cap.

    Never exceed the voltage rating of a cap, or you will likely destroy it very quickly.
     
    Last edited: Feb 25, 2010
  8. BMorse

    Senior Member

    Sep 26, 2009
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    As for the main topic at hand..... (spot welder aside, since wont do much good with the engraver ;))....


    This would make a good alternative to making your own high speed spindle (That could be later on, we will keep it as basic and simple....)

    [​IMG]

    One thing to keep on hand though, are some replacement brushes for these, running them as engraver and for milling pcb's can sometimes take hours, depending on how intricate the pcb is, so the brushes wear out pretty fast, and will cause problems. When those babies start arcing and causing all kinds of electrical noise in the system and may cause your machine to "miss" a step or 2 (a lot!), and trust me on this one, a couple of steps in any of the axes, could and will ruin your work, especially with smd's.... so keep some spare brushes around normally these can be purchased at the same place you get dremmels and accessories....

    here is what it looks like when you miss or have extra steps every now and then while milling and drilling, this PCB consisted of over 8,000 lines of NC code, so a few extra here and there every few secs, adds up quick!!
    MISSED STEPS DRILLING.jpg

    here's another while milling....

    MISSED STEPS MILLING.jpg



    Also, this would be a must to have Flex shaft Pro.jpg
    , this will make it to where the Z axis does not have to be that large to hold the whole dremmel..... the dremmel can just hang off of something, (the ceiling.....) and the flex shaft is what will be attached to the machine for doing the work....

    this is my setup now with the dremmel flex shaft attachment ...
    [​IMG]


    >>>> http://www.sjdiscounttools.com/dre225.html
    This is the only flexible attachment I have used, some others may work, but the mounting could be different, just make sure it will work with your model dremmel.....


    My .02
     
    Last edited: Feb 25, 2010
  9. BMorse

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    Sep 26, 2009
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    This could serve as a high speed spindle motor later on, for now it has no use for building the axis's.....

    These ones, not good...... very low torque, especially the bottom steppers...... only made to move pieces of paper, even those jam it up sometimes......


    Save the encoder disc off of this one, you may be able to use it later on for a tachometer for the high speed spindle..... or something... the motor, not very useful for this project either....

    B. Morse
     
  10. R!f@@

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    I'm off to a bad start...
    BMorse.. I think you might be thinking this is a big one but I don't want a big one.
    The max bed size would be A4 paper size. that's all I need for now.
    Do you think what I have right now would suffice for a small drill.
    I am not going to give up yet.
    If it can be done it will be done, I just need a positive answer, I can always get new steppers if I want but the real deal is to start it. I need a working model to begin with.
    I am not going to stop here yet, the tacho meter is almost done now, problem is measuring the torque. I still have no idea on it.
    One thing at a time. It took me a couple of hours to find all of them from here and there.
    So for now just tell me how I can measure the torque of these motors, and how are you applying them to something that's not yet made. what I am saying is that how can one tell whether this particular motor cannot move a tiny bed or a rotate a shaft. There must be some figures or some math involved in this.
    Do you still think that the ones I have is not going to cut it. :(
     
  11. BMorse

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    A4 size is not much different than my machines size, my work table is only 16" x 12", which is really not much bigger than A4 (Legal Size)paper....


    here, read this, this helped me figure out some math on how to figure out the size of motors and screw drives you will need, thanks to Arvid Brodin (arvidb at CNCzone.com).
    View attachment CNCMechanics v1 21.pdf


    or go here for a tutorial >>> http://www.piclist.com/techref/io/stepper/measure-torque-rb.htm
    Thanks to our very own TheRB (Roman Black).....
     
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  12. BMorse

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    You will still be able to build a very lightweight cnc with those, but it will be very slow and it may be able to handle the flex shaft adapter for the dremmel.... but you can definately forget about the high speed spindle, this will be much too heavy of a load for the motors you have........ Even if you managed to build a small one that can draw with a pen, that would still be quite an accomplishment, and it will give you plenty of experience in building these, then you will know what to do, and how to do it better the next time you build another.....


    Did you see this thing I built as one of my first protoypes?? That is all this could do was move a pen and draw on paper... but it was a good learning tool...

    [​IMG]
    B. Morse
     
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  13. R!f@@

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    Nice... that was the first idea
    Now that I see it, it all makes sense.
    But I'm not giving up yet....:p
    I'll be back....<ARNOLD>

    .........Torque and rpm measurements on going....will be updated ASAP........
     
    Last edited: Feb 25, 2010
  14. shortbus

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    Sep 30, 2009
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    In the other thread R!f@@ talked about using drivers for his steppers then went on to say he was getting PICs to go with the drivers and the PC.

    My question to BMorse is why do you need a PIC? I thought all you needed was -a PC, a breakout board, and a driver. Could you explain?

    Oh, what CAD-CAM program do you use?

    cary
     
  15. BMorse

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    Well, I think there was a little confusion..... I use pics to drive the phases of my steppers instead of a stepper controller IC, this acts as the bridge between PC and motors......

    You can either go through the trouble of writing code to properly sequence the phases for controlling the stepper, OR you can use a standalone stepper controller IC..... which in this case is what I was suggesting for R!F@@ to use....

    as for the CAD-CAM software, most of my milling files for PCB's are created using Eagle (running the PCB-GCODE.ulp produces the top, bottom milling file and the NC Drill file.)

    I then import that into KCAM by Kellyware (A low cost shareware application.... cheaper than MACH3....) to run the cnc......

    For other things I mill and engrave, I use turbocad or any other CAD program than can export it to dxf, which can then be imported into KCAM...

    + A bunch of other freeware apps for doing all sorts of other things with the machine....:D

    B. Morse
     
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  16. R!f@@

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    BMorse, Alberto.
    Do you think these are a better alternative to the ones I have, and will suffice the future enhancement so to say.
    Or should I still experiment on the ones I have for their capability.
     
  17. BMorse

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    Sep 26, 2009
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    The motors he posted are exactly the same type of stepper I am using (56x56mm - Nema 23) so these would definitely give you a better machine.... but of course then you are increasing the cost to build your project....

    And if you are going to spend that kind of money on just motors, might as well go for the motor and driver kit like this >>> http://www.hobbycnc.com/products/hobbycnc-ez-driver-board-packages/

    B. Morse
     
  18. R!f@@

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    You guys are still underestimating me :cool:.
    It's not the electronics I am worried about. I can virtually construct any thing on a PCB. It's the hardware that I don't have.
    BMorse, what do u think of this one
    Will it suffice for a suitable table.
    The interface and stepper drivers is child's play to me :cool:, well at least the drivers are, still I doubt on the PCB interface part.
    But it will be at a later stage. For now I am worried about the axis motion hardware.
     
  19. BMorse

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    Wood frames are ok, but you have to realize that wood has a tendency of warping / shrinking after a while, especially if in a high humidity area, the wood will expand and contract...... so It would be good for a while, but you might end up maintaining way too often....and I would not know how well it would keep its axis's aligned.......BUT, it would still not be bad for a starter machine.......

    B. Morse
     
  20. R!f@@

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    My thoughts exactly.

    I'm having a hard time running the tacho, with a PIC16F628 and 20x2 LCD.
    I thinks the LCD command set is giving me problem, and may be the 4Mhz Xtal.
    Circuit uses a 2 pin one, what I have is 3 pin one.
    So I think I will enable the internal oscillator.
    question is will it hinder the RPM accuracy reading? :confused:
     
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