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  1. #1
    so in another thread that i hijacked http://www.mycncuk.com/forums/showth...-Driver-Boards

    i thought id start another.

    i found this http://www.ebay.co.uk/itm/CNC-Router...item2a1a92096e
    on ebay after being told the all in 1 boards are Cr@p,

    seems alot more expensive than this
    http://www.ebay.co.uk/itm/3-AXIS-CNC...ht_5121wt_1052

    as i need motors etc. this is my first build so any advise on the above links..

    ie what motors and psu would be suitable.

    my first table will be say 4x4 to start but theres always an upgrade in size.
    mainly cutting mdf and ply... perspex/acrylic

    thanks

  2. #2
    Just dinnae go near TB6560 based drivers, they are a short route to frustration.

    Have just blown second 6560 in less than a month, guessing its actually back emf that kills them, this one was Y axis driver after fine engraving, lot of Y back and forth think the driver either thermally cooks or direction change kills the output devices.

    Most expensive is having a piece of equipment sitting idle waiting for parts.

    Personally thinking either 542 or Gecko boards to replace the fragile 6560s...

    http://www.charter-controls.com/inde...b_y=0&offset=5

    4X4 is actually a large table and cost of motors and drives will be a small part.

    Cheers
    Adam

  3. #3
    Don't go anywhere near either of those.!!. . . Bad news.

    I urge you not to rush into buying any motors or drives, psu etc untill you have fully got the design and know the components like ballscrews pitch etc and mass to be moved.

    One of the biggest mistakes folks new make is to rushout and buy motors etc then regret it because they either arn't large enough or just plane rubbish like the ebay offerings.
    The other often misunderstood is voltage and it's very common for folks to buy too lower voltage PSU's that don't get the best out of the motors. the other is to buy drives with too low voltage limit.
    Stepper Motors work best with high voltage, a typical motor would be nema 23 at 3nm. These motors perform best with around 60-70V but it's very common for people to buy drives with a 50V limit and even more common to use 36V psu's with these drives. (Namely because they are sold in kits like this from suppliers like cnc4you etc or the only PSU's they supply are 36Vor 48V)
    So as you can see the machine would be quite crippled with a setup like this and trust me it happens often because I'm always helping people who have been sold this kind of setup.

    It's not difficult choosing the right setup but does need carefull attention and really if you want to get it right first time then don't try saving pennies because it will cost you pounds further down the line and lots of frustration.

    Decide on the machine size, style and it's components then ask. Then and only then start buying expensive items which are critical to a good cnc machine like drives and PSU's, motors are relatively cheap in the grand scheme but can easily be crippled with the wrong choices.

  4. #4
    thanks all for the replys, ive gone with the m542 drivers... so now ill be needing motors and psu...
    what would we sudjest.. ive thought about it a like my work tools id like to invest in parts that i dont need to upgrade...
    what do you think. have i made a mistake in choosing the m542 drivers, they arrived today...

  5. #5
    m542 drivers are good, glad yours arrived.

    3Nm motors will be good for that size. You could get away with slightly smaller motors but the cost saving is minimal so I wouldn't bother. These are currently the cheapest:

    http://www.cnc4you.co.uk/index.php?r...&product_id=67

    You want a PSU just short of 50V. The cheapest way is to buy a toroidal transformer (500VA minimum for four 3Nm motors, 35V max), bridge rectifier and capacitors to make your own PSU.

  6. #6

  7. #7
    That's good, but not the cheapest.

    http://www.rapidonline.com/Electrica...-0-35v-88-3839

    (They come up cheaper on eBay quite regularly.)

    With capacitors and bridge rectifier (5 max) will be just as good if not better. You can find the circuit on google easily...

  8. #8
    Quote Originally Posted by Jonathan View Post
    That's good, but not the cheapest.

    http://www.rapidonline.com/Electrica...-0-35v-88-3839

    (They come up cheaper on eBay quite regularly.)



    With capacitors and bridge rectifier (5 max) will be just as good if not better. You can find the circuit on google easily...
    sorry im confused, you said a transformer around 50v, the one in the link is 0-35v.. what cap and bridge rectifier would i need...

    also is there a thread or diagram i could use...
    Last edited by crossleymarko; 04-04-2012 at 09:26 PM.

  9. #9
    Quote Originally Posted by crossleymarko View Post
    sorry im confused, you said a transformer around 50v, the one in the link is 0-35v.. what cap and bridge rectifier would i need...

    also is there a thread or diagram i could use...
    Due to the capacitors the open circuit voltage will be the peak voltage, not the RMS voltage of the sinusoidal waveform from the transformer. To (approximately) find the ouput voltage you therefore multiply by the square root of 2 and subtract about 1.2V for the diode forward voltage, hence 35*2^0.5-1.2=48.3V.

    Bride rectifier:
    http://www.rapidonline.com/Electroni...ctifiers-66254

    Capacitor (3 or 4 in parallel):
    http://www.rapidonline.com/Electroni...acitor-11-2993

    The transformer has two 120V primary windings, so you connect them in series to get 240V then connect that to the mains via a fuse. There are two secondaries and you want the rated voltage, so put them in parallel to keep 35V but get twice the current and connect those two wires to the AC terminals of the bridge rectifier (marked '~'). The output waveform will now look similar to a loch-ness monster, so connect all the capacitors in parallel with the + and - terminals of the rectifier and double check the polarity is correct (if not they literally go bang).
    If you're not sure then read up on it or just get the PSU on eBay.

  10. #10
    quick search and found this...http://www.e-dan.co.uk/electronics/wiringtrans.html
    im confident in doing this but need steering in the right direction... are all the wire colours on the tororial universal...?

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