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Thread: Got my BT48 running...

  1. #1
    Join Date
    Sep 2012
    Location
    Blaine Mn
    Posts
    292

    Default Got my BT48 running...

    I finally got my VFD fixed and it works. I have switched the X and Y axis and I am feeling out the real limits of the table and surfacing the spoil board- I am going to add a spoilboard on top of the factory one for now as it is already surfaced below the surface. I would like to build an alum extrusion table similar to Andrew's eventually.

    This is an Alpha tool and I am still figuring that out, I often run up against the limit switches [trying to get a bit more tool travel] and then I have to Quit and Reset in order to regain manual control? I am not sure what is happening when I push reset? The tool has lost track of it's position- do I have to do a C3 before it knows accurately where it is? I am trying to get a handle on how this works. Thanks Gene

    And Tom- you were right about the VFD of course. Apparently a poorly crimped connector which rattled loose on the ride up from Virginia. Very happy with the machine in spite of the problems.

  2. #2
    Join Date
    Jun 2015
    Location
    Durham NC
    Posts
    57

    Default

    Good to hear it is working again for you, Gene.

    When you physically crash the alpha step motors (run it up against a physical stop) the closed loop steppers fault and let the control system know that they have lost position, when this happens the controller engages an E-Stop and drops power to the motors to stop the tool motion. When this E-Stop is triggered there are some relays in your control box that go into an "off" or open position. This behavior is what drops power to the motors. At this point, yes the tool has now lost position and your relays are disengaged.
    Next you have to hit RESET, when you push reset a signal is sent to engage these relays back into the "on" or closed position, powering the motors once again. The "clunk" sound you hear when you press reset are these relays pulling in. You'll now want to run a C3 and a C2 (zero the XY and Z) as all motors lost power when the event occurred.

    With any tool it is always important to be mindful of our physical limits and not exceed them. With a Standard (open loop) tool if we run into these hard limits (and aren't using software based limits) the tool will lose position, but continue cutting. Ruining the final cut. With the Alpha system, the closed loop steppers prevent this failure in the final cut by erroring out, but still cause us a delay to rectify the error.

    -Tom

  3. #3
    Join Date
    Sep 2012
    Location
    Blaine Mn
    Posts
    292

    Default

    Thank you, Sir. I have not been able to find out much about the difference between Standard [of which I have had two] and the Alphas, except they are better, with out much explanation why. Gene

  4. #4
    Join Date
    Mar 2013
    Location
    Memphis TN
    Posts
    583

    Default

    ShopBot Details:
    PRS Alpha 96x60x12
    4hp Spindle
    12" indexer
    Aspire
    Rhino

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