Repeated slop in gantry

This topic contains 5 replies, has 3 voices, and was last updated by  Dave S 4 months ago.

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  • #101274

    Dave S
    Participant

    Has any one experienced repeated slop showing up in the gantry?

    I have gaps that show up between the rails and the lower outer bearing in the XY parts.   I can tighten the A Tension bolts and get rid of it, but it creeps back in after a few cuts.   Aluminum makes it show faster.   I am at the point with the A bolts that the bearing is getting crushed and starting to drag on the plastic.  Can’t be good.  Picture shows where I am seeing the gap when I jiggle the Z-axis.

    Is there a better or worse brand of PLA I should use?   I was using 3D Solutech Apple Green.  But have some new Hatchbox Orange.  Both Standard PLA.   Maybe the 3D Solutech is softer stuff?

    I’ve already rebuilt the gantry with new parts.  The second set was not any better though,  in fact the A-tension bolts were very loose to start with.  See video.  Rest of bolt holes were spot on (which I can’t explain, why wouldn’t they all be off same way?).  While first time around I had to drill them all out to 5/16.  I think the looseness was a combo of the partially threaded bolt shaft being small (.304-.307), and the hole printed slightly large.   I shimmed bolt with tape to center and snug it up before finishing the assembly.  But in the end the gaps still creep in after a while.

    #101280

    Ryan
    Keymaster

    Check the calibration of your printer. Not Just XYZ, check all the diagonals as well, minimum of 100mm. Lots of printers seem good until you realize one of the axis is leaning really far. There is a recent picture of an XY block leaning at least 1/4″.

    #101285

    Dave S
    Participant

    You mean my 3D printer?  I am running a delta (Rostock Max V2 from SeeMeCNC).  I’ve done a number calibration cubes and such, but nothing that large.   The baby ones (20-25mm) all seem pretty close (+/- .1 – 2 mm)  Not sure about lean though.    I’ll run a big one tonight though and see how it looks.

    I have not checked general perpendicularity on the CNC either.     Did not think it would matter if cut surfaces got stripey since most of my plans did not involve too much facing. But I will.   I have had mostly bad luck with aluminum, and recently read that could be part of the problem.   Wondering if weight of the router is enough to tilt it out of whack.

    Thanks.

    #101292

    Ryan
    Keymaster

    Unless your printer is so far off it barely works a 20mm cube teaches you nothing. There are all kinds of larger style calibration parts without having to print a 100mm cube. With your specs you are easily 1mm/100mm off, but like I said diagonals are more important as those never get checked.

    Don’t worry about metal cutting until you are fluent in wood and plastic. If your bearings are not touching and you are squeezing parts you cnc is not in the right shape for metals.

    #101294

    Barry
    Participant

    You can do a 50mm by 50mm by 200mm calibration block and just print it in vase mode.

    #101343

    Dave S
    Participant

    I printed a 100x100x40ish block in vase mode.  The result was pretty good.  +/- .1 every way I measure.   Diagonals match XY to within .1 as well at depending on how far up or down I angle my calipers.  I could not get good measurements Z or Z diagonals.   I ran out of filament and the reload go jammed.   Which is why it ended up 40ish and teh top is all messed.    Will make a good cup to hold all my clampy bits laying around.

    I determined that the router is definitely not perpendicular though.   Using the gauge you put on Thingiverse.     It seemed to be off in the direction the tool is mounted, by approximately 3/16″.    I shimmed between the tool holder and mount with some aluminum strips that could form against the curved surface of the mount.  Approximately 2mm thick.   Seems to have correct it.   Will run some test cuts tonight.

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