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  1. #1
    Hi All,

    Firstly, thank you to all you chaps who provide such useful advice here.

    I recently bought a 3018 pro from ebay. You would not think you could go wrong for 140. As an electronics engineer I wanted the machine to make rapid prototype PCBs.

    There are three problems with the machine from the off. Two are electronics related so I feel they are fixable easily enough. The third is mechanical.

    Problem 1 is that a surface mount fuse on the controller PCB has blown. No idea why it blew, but the controller is completely dead. I can temporarily solder a very fine wire across the fuse and I can power the machine up using a lab supply with a settable current limit as a stop-gap solution. I'll order some replacement fuses as soon as I've figured out the correct rating.

    Problem 2 is that one of the three small stepper driver PCBs is faulty. Initially I thought the problem was with a stiff axis because it was stalling and missing steps. However, it is clear that the motor torque when using the faulty driver module is way down compared to when the other driver modules are being used. The module is based on the A4988 driver device. I have already ordered some replacements from ebay.

    Problem 3 is more difficult (in my head, at least) as my mechanical skills, experience and resources are not great. The "loose" end of the Y axis lead screw fits into a small bearing fitted to the front rail of the machine, which is made from bakelite. The bearing has not been pressed squarely into the rail so the lead screw does not marry up with the stepper motor on the back rail of the machine. The mis-alignment is enough to prevent the lead screw from rotating if it is forced into place. I am thinking that I might be able to get the bearing out if I can rig up a rudimentary press using maybe a vice, a small 1/4" square drive socket to push, and some plywood to support the rail, with a hole drilled in the plywood to accept the bearing.

    However, i'm worried that I may break the bearing or the rail. The screw is 8mm diameter, the bearing is 16mm OD but the hole I need to use for access to push the bearing is only 10mm diameter. So I could only press against the inner half of the bearing and I worry it would just break.

    I'm also wondering if it is worthwhile to try and use a vice to press the bearing properly home instead.

    Any thoughts or advice would be very welcome.

    Many thanks,

    Paul





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  2. #2
    It sounds like you bought your machine from the same place I did.
    Mine is flawless... I suppose the variation in build quality is expected at that price really. I probably dropped lucky.

    I'm sure you've tried this, but have you.. tried swapping around the axis driver PCB's to make sure one of them is faulty and that it's not
    some sort of problem with the stepper itself?

    I haven't tried pressing out the bearing in a vice.. but that's how I'd do it. bearings are tougher than you think. Just don't hammer anything!

  3. #3
    Kitwn's Avatar
    Lives in Exmouth, Australia. Last Activity: 8 Hours Ago Has been a member for 2-3 years. Has a total post count of 474. Received thanks 64 times, giving thanks to others 11 times.
    Welcome Paul.
    An electronics engineer who calls himself RadioBeamer... Someone else into high power wireless telegraphy I suspect
    Last edited by Kitwn; 1 Week Ago at 07:50 AM.
    Engineering is the art of doing for ten shillings what any fool can do for a pound.
    Wellington.

  4. #4
    Hi there, yes, you figured me out. I'm a radio communications enthusiast.

    Not getting anywhere with my 3018 ebay seller though. Might have to give some negative feedback on ebay,

    Thanks Richard. I already swapped over the stepper driver modules and the problem is definitely that one of them is defective. However, that is a a bit of a secondary consideration until I get the Y axis assembled properly. Still working on that.

    Cheers,

    Paul

  5. #5
    Have you tried using a hair-drier to warm up the plastic surrounding the bearing? They're just 3D-printed and so the material should soften.

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