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  1. #31
    Tom's Avatar
    Location unknown. Last Activity: 30-11-2016 Has been a member for 7-8 years. Has a total post count of 172. Referred 1 members to the community.
    What drivers do you have?
    I bought the "standard" 18-50V, 4.2A max drivers that everyone seems to be selling (black cases, green terminal blocks). Got mine from Arc Euro Trade at a very fair price with free shipping. I recon they compare OK with geckos.

    if no good I'll buy em off you :D
    Cheers for the offer, but you should buy your own! I'm confident they'll be good!
    Seriously though, have you got your 'lectrics sorted yet, or is that the next step?

    I'm going to order one of those power supplies and a resistor... Cheers again for the link....

  2. Nice powersupplies and i've ordered two (can never have too many supplies hanging around!)

    Note though you may need to use a reverse energy dump circuit with this supply as it has an over-volts latch off function if the output voltage exceeds 60v. With a large stepper under load the reverse EMF could cause the over-volt trip to shut the supply down (sort of like a self-inflicted e-stop)

    It shouldnt be hard to tweak it to go below 50v. When I get it I'll have a look, also will advise on best way to replace the output connector with something more cost effective as the DIN41612H connectors are 10+ each without the shells. The connector on the supply is a male, so it may be possible to use female push-fit spade connectors directly on the terminal pins.
    Last edited by irving2008; 28-06-2009 at 06:45 PM.

  3. #33
    Tom's Avatar
    Location unknown. Last Activity: 30-11-2016 Has been a member for 7-8 years. Has a total post count of 172. Referred 1 members to the community.
    shouldnt be hard to tweak it to go below 50v. When I get it I'll have a look, also will advise on best way to replace the output connector with something more cost effective as the DIN41612H connectors are 10+ each without the shells. The connector on the supply is a male, so it may be possible to use female push-fit spade connectors directly on the terminal pins.
    Thanks Irving,

    I was hoping spade connectors would fit too, otherwise I was just planning to solder directly to the pins (not pretty), or open the box and find another way.

    I'd read about energy dumps for back EMF during deceleration, but didn't think that would affect steppers so badly. Anyway, it would be great if you could let me know about voltage adjustment when you get the supplies.....

  4. #34
    Tom's Avatar
    Location unknown. Last Activity: 30-11-2016 Has been a member for 7-8 years. Has a total post count of 172. Referred 1 members to the community.
    OK then,

    The summer has been had, the long evenings have long gone, and it's time to get back to the CNC router build.

    Over the last couple of weeks I've been getting things back in shape (mainly remembering where I'd put everything). I got the electrical panel built during a day off work a fortnight ago - once I saw the motors singing there's no way I'm stopping!

    Here's a video of the YZ gantry moving.
    Y travel is 480mm, Z travel is 100mm in this video but it will go further.
    These are G00 moves and the speed seems quite good (but it may be losing steps - need to check with some dial gauge tests when its on the x table).
    I'll post the current EMC2 accelerations and velocities next time I'm near that computer.



    Next jobs:
    Mounting the X axis leadscrew and nut.
    Then limit switches and a bodged up router mount.
    Then (quickly before it all falls apart) I'll need to mill an MDF router mount, followed by decent motor mounts (they're pretty heath robinson at the mo).
    Finally, make a few xmas presents on it... :) (time is v short)

    Photos:
    Pic of the front
    Bodged temporary motor mounts
    Rear of the Z carriage
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    Last edited by Tom; 03-01-2010 at 04:30 PM. Reason: fix broken link

  5. #35
    jonm's Avatar
    Location unknown. Last Activity: 19-06-2011 Has been a member for 7-8 years. Has a total post count of 89.
    hi tom
    could you tell what breakout board you used with the euro arc trader drivers, i looked at these are they ok


    thanks

  6. #36
    Tom's Avatar
    Location unknown. Last Activity: 30-11-2016 Has been a member for 7-8 years. Has a total post count of 172. Referred 1 members to the community.
    Hi Jon,

    I'm very happy with the drivers. I've not worked them hard yet, but they have a decent feel of quality. They're on offer at Arc Euro at the mo - For 39 I can't find a complaint...

    I bought a readymade breakoutboard from DIYCNC (PCPPS-2). This is the simple board which is not opto-isolated. As far as I remember the inputs to the drivers are opto-isolated so I decided there was no need to double-up. Also I have a scrapper of a PC running EMC2, and I'm not doing anything commercial, so the consequence of a fried motherboard is not too serious (also unlikely).

    I got the one with a charge pump to improve safety, and it also has a voltage regulator to provide 5V for the limit switches, which is handy...

  7. #37
    jonm's Avatar
    Location unknown. Last Activity: 19-06-2011 Has been a member for 7-8 years. Has a total post count of 89.
    hi tom
    thanks for reply i am using the system 3+ board from diycnc
    with 3nm steppers board limit is 30v , i think i could do with more voltage on these steppers , its always good to hear positive feedback before you buy, 39 each aint bad may give em a try

    thanks

  8. #38
    Tom's Avatar
    Location unknown. Last Activity: 30-11-2016 Has been a member for 7-8 years. Has a total post count of 172. Referred 1 members to the community.
    The shakedown runs of this router are finished, and I'm growing in confidence with it.... Purely for posterity here is a before screengrab from sketchup, and an actual photo of the thing for real! (complete with deadly MDF dust)

    There are a couple of weaknesses with it so far. Some are easy to build out with some re-cut panels, which I'm in the process of doing. Others are slightly more fundamental (but happily, not too serious).

    Improvements to make:
    1) The gantry is not sufficiently strong along the Y direction. Looking at it now it's obvious! But there are no diagonals, and I'm re-cutting these before even attempting alu. If you remember, this is supposed to be an alu sandwich router, but it's going to need gantry #2 before I can cut the alu for gantry #3...

    2) The X leadscrew is not perfectly straight (well actually, bent!), and combined with the poorly braced gantry leads to wavy sides (pitch of 4mm!) on the x edges of parts I cut. Hopefully the braced gantry will fix this. If not, a new screw....

    3) Some poorly placed drill-holes during the initial build means that at the moment the Z axis sits a couple of degrees away from vertical. The collet end of the router hands back under the gantry. Again, some re-cut panels (with computer aligned holes, not pencil aligned ones) will solve this.

    4) The final, slightly more thorny problem is that the Y rail support twists slightly (tucks under) in the x direction, when the router is at full Z travel down. The problem is worst in the centre of the Y travel. A fix to this would involve spacing the Y rails further apart, and re-drilling the Z carriage to accept new skate bearing positions. It's not impossible, but I will try alu skinning first, possibly followed by replacing that piece of MDF with a chunk of solid alu if that doesn't work (it's only 100mm x 700mm).

    Current max axis speeds are (so I don't forget):
    X 40mm/s, accel 80mm/s/s
    Y 100mm/s, accel 110mm/s/s
    Z 30mm/s, accel 60mm/s/s

    X and Z are conservative, put there to stop the machine shaking itself to bits with a wobbly gantry and bent screw. I hope to increase these as the improvements are added...

    A happy speed I've found for cutting MDF so far is 1800mm/min, with a 6mm 2flute mill, and 4mm of cut on each pass. This is definitely limited by the current rigidity of the machine, but onwards and upwards... Rooolll on the improvements....
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  9. #39
    Tom's Avatar
    Location unknown. Last Activity: 30-11-2016 Has been a member for 7-8 years. Has a total post count of 172. Referred 1 members to the community.
    Here's the first really pleasurable job i've done on it... This was fun, a small oak box as an xmas present...

    Pics:
    1) ProgeCad
    2) CamBam
    3) EMC2
    4&5) The finished article (too many straight lines though )

    (oh by the way, there was some belt sanding involved - unfortunately didn't come off the machine looking like that! :)
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  10. #40
    Tom's Avatar
    Location unknown. Last Activity: 30-11-2016 Has been a member for 7-8 years. Has a total post count of 172. Referred 1 members to the community.
    Happy New Year!

    I've spent part of this holiday getting my router into better condition. I'm surprised at how much time it takes to go from a machine that moves, to one you can walk away from during a job. I still have to pounce on the E-stop too often!

    There are some photos of the latest changes.
    Major one is that the new gantry is now fitted. This is now 18mm MDF (was 12mm), and it has bracing round the corners which improves the rigidity massively! It's fixed problems 1 to 3 in my earlier post. I think the aluminium skins are still worth adding, but that will be in a few more months when it's earned some money!

    A smaller change is that i've added flexi conduit to control the cables. This has tidied it up immensely, and is a major step towards the day when I can sit in another room with a cuppa while the machine's running! lol Unfortunately it's two steps forwards, one step back - it doesn't bl***y work any more because of electrical noise issues which keep tripping the limit inputs during a run.

    I shouldn't be surprised - the motor and signal cables are both unscreened, and they're now running in the same conduit in some places. There's some lovely screened motor cable on it's way to me now. For the screened signal cable I'm going to butcher a network cable, which is an idea I've pinched from Robin's Mill Build Log

    Lesson learned - make it bombproof from day one!
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