Bumps in part?

This topic contains 6 replies, has 5 voices, and was last updated by  Kevin Russell 6 days, 8 hours ago.

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  • #120236

    Jeff
    Participant

    I’m trying to make a little box, with a lid that would nest inside a pocket. The problem I am running into is when running the part cut, I am getting a bump on each pass in the same spot on both the base and the lid. I’m not sure what is happening. I am running a finishing finishing pass on both parts. Any suggestions?

    I mean I know I could hit it with the belt sander and clean it up before applying finish, I just though it odd as its only happening on the part operation and not the pocket or island operations.

    This was with Estlcam:

    .Estlcam1

    Estlcam2

    And this was with Fusion360

    F360

    I checked the belts and gear screws, all looked and felt okay. A bit odd. Any help is always appreciated.

    #120302

    David Walling
    Participant

    check your bearings and your rods. The machine his hitting something causing it to jog in the direction of the bump.

    Move the device to another part of the table and try the cut there. See if it still does it. If it still does it, then I’d be taking a closer look at the G-code.

    2 users thanked author for this post.
    #120401

    Andrew
    Participant

    I was having this same issue on my first cuts.  It was happening to the left and bottom sides of the part, and only the part, not in the pockets.  It looked exactly like the issue you are having.  I use estlcam.  When you import a DXF into estlcam, it places the file right on the x and y zero lines.  When the part I was cutting out was directly on the x or y zero line the machine would jump in the exact same spot on every pass, including the finishing passes.  When i moved my zero, the problem was fixed!  Took me a while to figure out.  I now set my zero point about .125″ down and to the left of the line I am trying to cut and have never had the issue again.  No idea what causes this.

    Hopefully this helps and saves you some trouble.

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    #120404

    Andrew
    Participant

    second image did not post.  Here is the second image with the zero moved over about .125″

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    #120406

    Jamie
    Participant

    It looks like it is directly above one of the holding tabs.  Is that by chance the location where the Z depth increases?

    Also are you using climb milling?  And how much are you taking off on your finishing pass?  Conventional milling and a finishing allowance that’s too small might not clean up the anomalies from the first pass.

    1 user thanked author for this post.
    #120415

    Jeff
    Participant

    After a days work to think about the problem and to reflect on what you all have written, thank you by the way. I think I’ve found when the problem is occurring.

    David, I did think this might be the problem, when the gantry is running across that section of tube some sort of binding or a irregularity on the tube might be causing this. But when looking at the rest of the part such as the pocket there is no bump or indent in those locations, and the irregularity happens in two different spots.

    Andrew, I never start my cut inline with x0 and y0, I always use an offset, I figure it might mess with my cuts. Thank you for pointing that out and confirming my suspicions.

    Jamie, I thought that might be the issue so I loaded up Estlcam and Fusion360 to check the holding tabs. What I found was the bumps are happening where the tool is plunging into the cut on the Z axis.

    Looking at the Estlcam tool set up I have a plunge angle set to 90, I wonder if I set it to more of a slope if that would clean it up. As for conventional vs climb milling, I’m not sure how to set that in Estlcam but in F360 I am using climb milling.

    #120425

    Kevin Russell
    Participant

    I get bumps like that wherever I have holding tabs in Estlcam.  It happens even when the material is 23mm thick and the tabs are only 2 mm high.  I haven’t looked into the code or tried other software yet to generate the gcode.

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