What size should conduit holes be?

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This topic contains 6 replies, has 3 voices, and was last updated by  John 1 year, 6 months ago.

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  • #10966

    John
    Participant

    like some other users, the holes that the conduit slips into on all pieces are a little too small. I have to either adjust the holes or stretch the clamp down area. I can fit the conduit in but it stretches out the piece a bit. I can do this easily since I printed in PETG but I am not sure if I should.

    I figure that I will just make a custom bit for my drill press to widen these holes a bit. I am wondering what size they should be when printed?

    #10970

    Ryan
    Keymaster

    Mine show up .2mm-.25mm under the size show in the for the version.

    Make sure you are sanding or filing your conduit edges before jamming them in there that seems to make things not fit for some reason. You’d think the sharp edge would file down the hole as you are pushing it through but it seems to actually just make it worse.

    The piece are a tension fit and should flex a bit, without this the whole assembly would be very flexible. Think of it as pre-loading.

    Also do a calibration cube print to check your printer and also make sure it is printing square, just a had a user this morning find out his printer does not print square, even thought the calibration cube is within specs he was getting 90 degree walls. Over extrusion is the most common issue though.

    The parts have been out there a while now with hundreds of builds, at this point I am pretty certain the parts aren’t usually the issue.

    #10974

    John
    Participant

    Yep, I am sure that it is something with the print as opposed to the design.

    #10982

    John
    Participant

    I checked my dimensions against the dimensions in Netfab. They all seem pretty close other than the holes. I am assuming that it is over extrusion like you said. I just to make things easier, I am pounding a 3/4″ spade but into 23.2mm. I will then clean throw it in my drill press and drill the holes to size. I think that this will be more accurate than sanding with a dremmel.

    #10999

    Barry
    Participant

    Good luck with that! Printed plastic doesn’t like drills very much. I tried drilling out a part and it just kinda melted around the bit.

    #11006

    John
    Participant

    This is where PETG comes in handy. I could see that being a problem with PLA however, PETG machines pretty well for a plastic.

    #11115

    John
    Participant

    I made a makeshift but which worked but tore up the inside a bit (PETG drills pretty well but my crapy hammered bit was a bit unstable). This works but its not pretty and it could mess up the part.

    I found a much easier way of dealing with the small holes: melting them

    I ground the tip of the conduit like Vicious suggested. I did this here to ensure that the very tip of the conduit would be small enough to fit inside the small hole. I then just heated the conduit a bit with my torch so it would melt the plastic and slide in. Grinding the tip helps ensure that the tip fits in the small hole and thus the hot pipe is centered when it is slid in. (sounds a little dirty, I know 😉 ). I was also able to rig up a square to help guide it in straight as well.

    I was worried that the hole would be too large but it is not. Additionally, this leaves a little residual plastic on the conduit which helps ensure a good grip as well. Using a square as a guide is also a good idea.

    If anyone else with the same issue does this, then make sure to be careful. Conduit is generally galvanized. when galvanized metal gets heated very high (it has to get extreemly hot for this but a torch can do it), then it vaporizes into a harmful gas. welders know it as metal fume fever.

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