Hello BMorse.

Discussion in 'Off-Topic' started by R!f@@, Feb 17, 2010.

  1. R!f@@

    Thread Starter AAC Fanatic!

    Apr 2, 2009
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    Hi
    I will be really great full if you can tell me what electronics would I need to build a small engraver cum router machine.
    The bed will be around the size of an A3 paper.
    What I like this mill to do is,
    1. Engrave, very fine lines
    2. Drill holes.
    All automatically.

    I want it to be controlled via my PC and I want to print cam files as well as corelDraw graphics .
    Now corel graphics will be just outlines. Not pictures.
    what do you call em files, vector files?

    I have plenty of steppers and small induction motors.
    I can do the metal frame works, I just like to know what are the components that I would need to build this.

    Thanks

    Rifaa
     
  2. BMorse

    Senior Member

    Sep 26, 2009
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    The electronics should be pretty simple....

    For each axis, since you want it to auto drill and all, you will need a 3 axis setup... and for each axis (Each axis control is the same for all 3).

    you will need stepper motor controllers capable of driving either a bipolar or unipolar steppers (you can do a closed loop DC Servo drive system but that just complicates things and most "off the shelf" items especially software is tailored more towards stepper control) I used bipolar (4 wire) steppers since these are the easiest to control (IMO), plus a lot of more common stepper motor controller IC's such as Allegro's SLA7062M, or the A3977 Microstepping motor controller IC, these are more suitable for Bipolar steppers (Plus you can get FREE samples!!:rolleyes:)....
    SLA7062 x4 Pic.jpg
    just got some in including the A3977 IC's....

    You can build these drivers with discrete components or, you can make them uc based, I used the UDN2998W Bipolar stepper driver for my NEMA23 Bipolar steppers, and controlled the phasing with a PC16F84A 2 20Mhz....
    Stepper control boards.jpg

    This way, all you have to supply via PC control is the step and direction for each controller which will make it compatible with MACH3 and also KCAM software.

    Anyway, so stepper controllers, and also 3 steppers that are capable of driving the loads you need (of course), something around 80oz tourqe/inch rated NEMA23 or higher....

    You will also need some way of connecting the controllers to the PC, preferably an LPT port :rolleyes:
    LPT Interface.jpg
    LPT Connections.jpg
    ... Most people tend to get too over complicated with buffers and other "not really needed" circuitry, my interface is simple and straight forward, it connects each axis step, direction Home switches and also lets me control the dremmel with an external relay so even the dremmels operation (on/off) is controlled automatically via the PC
    AC Interface Box.jpg ,
    and also the most important part of the machine, the Emergency stop button Estop.jpg ...

    so those are the basic electronic circuits you will need, 3 axis stepper controllers, an LPT interface, an AC interface, and an E-stop button...
     
    Last edited: Feb 17, 2010
  3. BMorse

    Senior Member

    Sep 26, 2009
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    on a side note from electronics (lets cover some of the more expensive parts you might need and some cheaper alternatives), you can get most of the hardware needed from www.Mcmaster.com, they have what they call ACME Screw's and Nuts, or any kind of threaded rod and matching nuts to use for the screw drives (or belts and pulleys for belt drives, I would not recommend the belt drive since it creates too much play in the movement of the gantries....)

    these are what would be suitable for CNC drives, I have seen people use coarse threaded 1/4-20 rod for the screw drives.... I used the 3/8" -12 ACME Rod (3/8" diameter, 12 turns per inch) >> http://www.mcmaster.com/#acme-threaded-rods-and-studs/=5v547f General purpose should work fine, you can always use a smaller diameter for your needs.....

    You can also use brass bushings as the rod end guides, less expensive than flange bearings...

    Bearings are another thing, on my setup I used 8 bearings per axis....
    each bearing would have cost around $40.00 dollars a piece :eek:, I got lucky and got 16 matching ones at the local scrap yard for $5 dollars (basically the price for scrap weight :rolleyes:).


    So the electonics are not really the costly part, it is the hardware for making a stable machine for doing some fine work is what is going to cost you, with the setup I Have I get around 2400 steps per inch (1.8 degree steps in a 360 degree rotation = 200 steps * 12 turns per inch = 2400 incremental steps per inch) so it is pretty accurate down to a couple thousandths of an inch!:D

    16 Lead QFN package for the MPR084Q Capacitive touch controller IC...
    [​IMG]

    so having a sturdy square frame and good drive systems are necessary to get small intricate work out of your machine....
    [​IMG]

    I even went as far as fabricating my own drive screw nut which I call the "360 degree offset compensating lead screw nut" (say that 3 times fast ;)) just to make sure I do not have any slack or play on any of my axis's...
    B. Morse
     
    Last edited: Feb 18, 2010
  4. R!f@@

    Thread Starter AAC Fanatic!

    Apr 2, 2009
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    Thanks Mate.
    So I'll start by collecting all the steppers I have, so that I can figure out what type they are.
    and so the journey begins.......

    Pls keep an eye on my thread, as I might be asking pointers from time to time.
    I'll be posting on this thread....
    One more thing I like to clarify is that I have a LD (LARGE VIDEO DISCS) Spindle drive motor which is rated at 24V I think, the bloody thing rotates at damn high RPM. Would it be appropriate to use it as the drill cum engraver motor.

    Cheers
    Rifaa
     
    Last edited: Feb 18, 2010
  5. BMorse

    Senior Member

    Sep 26, 2009
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    Most spindle motors I have used or seen being used are usually High RPM's (30,000 +) and high tourque, post a pic of the spindle motor so I can see what it is like.... What I use is a variable speed Dremmel Tool with the flexible "snake" attachment at it does really well......
    [​IMG]

    The reason why I used this is because it was easier to implement than a separate spindle and motor assembly, although I have made my own high speed spindle just in case i run into a suitable spindle drive motor...

    [​IMG]

    One thing with using a motor and spindle setup is the weight of it, you would definitely need a high tourque stepper to move it up and down, using the snake attachment for the dremmel all the Z carriage has to move is that, which is lighter than the dremmel itself, the dremmel is suspended above the machine....

    I will subscribe to this thread so I can keep track of it in case you need any more assistance..... if possible post some pics of your steppers...

    Brent Morse
     
  6. R!f@@

    Thread Starter AAC Fanatic!

    Apr 2, 2009
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    Thanks, I sure will Post pic's asap
    I do have a dremmel, I will post a pic soon.
    right now I am making a RPM meter so I can find the RPM's of my steppers and all.
    Regards

    Rifaa
     
  7. shortbus

    AAC Fanatic!

    Sep 30, 2009
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    Rifaa and BMorse, would you please keep this discussion on the forum and not go to PM's? I'm trying to do a similar build and I'm sure others here would be interested or are building too.

    Riffa - do you know about this forum? http://www.cnczone.com/ A lot of good info there.

    Riffa- your stepper RPM has to do with your driver. They only turn as fast as you tell them to.

    cary
     
  8. BMorse

    Senior Member

    Sep 26, 2009
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    I can definitely do that, no problem.....;)
     
  9. BMorse

    Senior Member

    Sep 26, 2009
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    TIP:

    When making your own screw drive's, I find it better to make your own screw lead nut, to make your own and to make sure you do not get any slack or play on the nut and screw lead, I used Delrin to make my own lead screw nuts (Delrin is a good machinable plastic that is wear resistant and very durable), what you do is cut a few inches of the threaded rod you are using (approx 3" to 4") and I tapered the end of the threaded rod on the grinding wheel, (or you can use a file just to put a slight taper on the end of the rod), If you have a Mill, this part would be easy to do, you need to cut some grooves in the threads 3/4's of the length of the rod, this will give you the cutting edge to "tap" the plastic and thread it. (If you don't have access to a mill, any orbital cutting disc should work, the grooves don't have to be perfect!)

    Now you have a "tap" to thread your "nuts" with the same exact thread pattern as the threaded rod, this will give you a nice snug fit and would reduce any backlash or play in the drive screws....

    threading tool.jpg

    My .02
     
  10. BMorse

    Senior Member

    Sep 26, 2009
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    Another Tip:

    Salvaging Steppers from old office equipment such as printers and or plotters are a good source for steppers, Home use scanners and printers (dot matrix ones anyway, most deskjets and inkjets use dc motors with encoders) also have some steppers but are usually too small for any milling / engraving applications. And the stepper control IC's can also be salvaged along with most of the passive components for its circuit, since most of these old plotters/Office printers used through hole components....

    Here are 2 complete Bipolar stepper motor controller boards I just recently built from salvaged components, the only thing not salvaged is the PIC16F84A and its passive components (Such as the crystal, etc.)....

    [​IMG]

    and here are the Salvaged Steppers I am using with them..... the belt drives and pulleys were also salvaged from other equipment.....

    [​IMG]

    Some equipment such as pen plotters / Vinyl Cutters can be easily converted to a CNC Mill.Engraver without hardly any modification to the hardware or drive circuits, and can be used as is.....

    steppers.jpg
     
    Last edited: Feb 19, 2010
  11. R!f@@

    Thread Starter AAC Fanatic!

    Apr 2, 2009
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    @BMorse
    About the screw drives you suggested, I was wondering about the clearance problem between the nut assy and screw, now since you have advised on it before I had a chance to ask about it made me think twice buying screw threads.
    Now I do not have a mill, but the institute that I worked had plenty of milling and lath's, and the lectures their handle both the practical parts as well, and they all are very close friend of mine.
    The milling and lath charges here are really expensive so I guess I have to talk to my colleagues to do this for me.But about that material you suggested, I don't think I can find it here since I am not familiar with it but I can get teflon of any size.
    I'm leaving all options open, so for now I'm trying to build the stepper drives, and like you said I also have plenty of junks with lot of drivers in 'em. I have been storing them for years hoping to built something useful from them even I had no ideas what I would built then. :D
    Right now I'm charging the camera,the darn thing is dead.

    @shortbus.
    Sure, no problem....now that you mentioned it.
    I was thinking of PM's before, did not know why. May be that I was unsure of BMorse wants.
    But now that the forum members wants to view how this project progresses, I'll be glad to share them, any thing for you well wishers.

    PS: I was thinking of putting up in my blog. :D

    Rifaa
     
  12. loosewire

    AAC Fanatic!

    Apr 25, 2008
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    I like seeing the results of team work,way to go guys.A lot of people
    will be helped by your work, pictures,that makes computers great.
     
  13. R!f@@

    Thread Starter AAC Fanatic!

    Apr 2, 2009
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    Hey shortbus..
    that CNC forum is huuuuuuuuuuuuge.
    I donno where to go, too many options makes my head spin.
    But I think there a lot of info .
    what do you think BMorse
     
  14. Wendy

    Moderator

    Mar 24, 2008
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    I have nothing to contribute, but I am following this thread with interest. This is a dream project, something I would like to do but probably never will.

    Given where it is going it would not have been unreasonable to be in the Electronics Chat Forum, though it is definitely other.
     
  15. R!f@@

    Thread Starter AAC Fanatic!

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    I didn't know that I have woken so many from slumber......:D
     
  16. BMorse

    Senior Member

    Sep 26, 2009
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    R!f@@:
    I have been to that site plenty of times in the past, thought about joining the forums about a year ago, a lot of usefull tidbits here and there.... but it is a lot of info to digest all at once ;)! Good thing their forums have a search function!:rolleyes:


    bill_Marsden:
    I had been dreaming about a CNC for years (Nearly 15 years!!!) You ought to see my prototypes I tried to make from various scavenged parts!! Here was one I tried to put together from various flatbed scanner and printer parts :D!
    Proto CNC.jpg

    Talk about "Frankenstein"!

    Anyway, dreams do come true, but you have to pursue them, they won't pursue you....:rolleyes:


    ----------------------------------------------------------------------

    Anyway, I have been thinking of coming up with Kits for the hardware portions, only the motors and driver circuits would have to be purchased or made separately (but those are widely available everywhere on the net, but I have not seen any CNC Mill kits that are in the "hobby" price range)... any thoughts????

    -----------------------------------------------------------------------
     
  17. BMorse

    Senior Member

    Sep 26, 2009
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    There is plenty of clearance for the nuts used for the screw drive, for the 3/8" diameter ACME screw I am using the nut is only 1" x 1" x 3/4"....

    Here is a sketch of the Offset compensating nut I designed, since you are not guaranteed a straight threaded rod, there will always be some curve or offset to it no matter how small of an offset, it could jam your machine or stall it, so I designed this to compensate for that....

    [​IMG]

    here it is after I made it, I made 2 of these, 1 for the X axis, and 1 for the Y axis, for the Z axis I used a brass nut....

    [​IMG]

    [​IMG]

    Here it is in place on the Y axis....

    [​IMG]

    and these are not that big to where they take up a lot of space either since my table capacity is only (Y)12"x(X)16"x(Z Depth)4" ..

    And yes, they can be made out of other material such as Nylon or even that cutting board material, just make sure it has low friction and good ability to resist wear....

    I have also seen some people would take 2 of the nuts and tighten them against each other to compensate for the play, this seems to work for some with the off the shelf screw lead nuts.


    I have also seen people use the coarse thread rod such as the 1/4-20 ANSI threaded rod which is only about 1/4" in diameter (20 turns per inch) and can flex too easily, also the threads are coarse and not machined so it would wear out the threads in the nut assembly pretty quickly, that is why I went with the ACME rod, since the threads are made for surface to surface gliding, so they are pretty smooth which will reduce wear on the nut threads.....


    You can find all kinds of ways to fabricate your own or modifying an existing one at the CNC forum....

    Mach3 Software also has the capability to compensate for backlash, so if you do end up with some play on the drive screws, you can compensate for it in software.... that option was not good enough for me so I opted to design my own lead screw nuts....


    But if you are one of those who has $$ to spend, you can go this route, >>> http://www.mcmaster.com/#ball-screw-nuts/=5w2vnq



     
    Last edited: Feb 19, 2010
  18. shortbus

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    Sep 30, 2009
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    Thank you both for agreeing to do this on forum! This has been a dream machine for me too. I can do manual machining(45 years as die maker) but to have a home CNC?

    I can't believe how high prices on Ebay have got for ball screws and linear motion parts in the last few years! That stuff was nothing a few years ago.

    Brent, I'm impressed with your machines!

    I have a some ball screws and linear motion stuff I picked up dumpster diving over the years that I'll try and use in mine. But first I've got to finish the Sinker EDM machine I started a long time ago. Got the mechanical stuff done just fighting the electronics.
     
  19. R!f@@

    Thread Starter AAC Fanatic!

    Apr 2, 2009
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    something had to come up as usual...
    Got the camera charged but I have to attend an LCD in between.
    It's kinda my thing. I trying to blog it now.
    It's rather confusing and time consuming .......
     
  20. R!f@@

    Thread Starter AAC Fanatic!

    Apr 2, 2009
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    Hey....It's late.
    There are somethings that I should get in order before I get this project started and into high gear. As you all know I have shifted and most of workshop stuff is stacked here and there and it is real hard to know which is in which box. As I remember I packed em really underneath some stuff, never thought that I would be using them any time sooner.
    And before that to drive the steppers and to test them I got to have a better PSU, and since this was something I wanted to build it seems this is the perfect opportunity. And it will come in handy for further projects. I have on hand one DMM, and I think I will need to take current readings together with voltage, so it's better to have built in meters in the PSU. I have plenty of parts for this and it can be done.
    so many things to do and so little time.
    I have finished setting up a nice bench in my living place just recently. So I guess the wheel is really going to go on this time and won't stop mid way, even though I am getting a few jobs and I have to attend them in order to cover my expenses, now that I am officially not working at all. :(

    So, every one who are keeping an eye on this, I like to remind you that this will be done but there are other things to set up before hand, and this might not progress at a higher speed as you might have expected.
    But it will be done, cause once my mind is set up on doing something I won't stop till it's done. A recent example is micro chip programing, I did say that I will learn and I have, and you can tell from my posts that how far I have progressed in such little time without any hand on help, other than from a few valued members in this forum. To me it seems this knowledge is really needed in what I am about to built. I think it is why I thought of building it suddenly.

    One more problem is the camera that I have is not that good, and I have to take pic's in high lit area to get em properly focused. I want the pic's to be large and clear from the very beginning, since it will be documented in my blog, and good pictures tells more than you can explain. I have a friend with one exceptional camera but he is on medical leave abroad and will be back in a few days.

    So all these facts puts a little bump on the road of the engraver. It will be over taken faster than you think. :D

    Keep in touch
    Regards

    Rifaa
     
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