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Thread: Lowrider CNC

  1. #81
    dkj4linux's Avatar
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    Quote Originally Posted by TheSFReader View Post
    I'm not sure I understand, but won't the bolt block some of the travel ? If I look at the pictures with your fingers undeside, even if the shuttle is at its highest position, the bolts would hit them at the gantry slides sideways.

    Would'nt it make more sens to block the bolt on the shuttle, and have the bearings on the gantry ? that way, as the shuttle is lifted, the bolts don't scratch/limit the surface underneath.
    The idea here is that the needle cutter/laser/etc doesn't actually require a lot of Z-axis travel in operation... once the business end of the tool is properly positioned above the work piece. Envision mounting the needle cutter so that it's needle guide extends below the heads of those guide rods (bolts)... even at the highest position. Yes, the bolt heads could be positioned quite close to the surface of the work piece but as long as they clear, they clear... they'll never move or interfere with movement of the cutter head over the work surface.

    The guide rods could, as you suggest, be firmly fixed to the shuttle and the printed bearings mounted to the carriage body... the guide rods would then move with the tool head and never be in the way. But, in this case, the relatively large/complex printed carriage was developed first... and it was easier, at the time, to simply fix the guide rods to the carriage -- for visualization of range of motion primarily -- and then come up with a shuttle/bearing system to fit.

    Remember, I'm just feeling my way along here...
    Last edited by dkj4linux; Today at 01:33 PM.

  2. #82
    dkj4linux's Avatar
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    Almost ready to test...

    I found a pineapple coupler in my MPCNC junk box, cut a short (~95mm) leadscrew, and completed the leadscrew assembly...

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    Attached to carriage body... there's just enough room for the coupler...

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    Lifted the shuttle and used pineapple to thread it onto the leadscrew...

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    Complete carriage with Z-lift assembly in place... may want to install guide rods (bolts) and bearings on other end of carriage/shuttle for balanced endstop if lower max is ever [inadvertently] reached and/or if binding seems to be a problem...

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    If I can find a place to attach those wires... it should be ready to test

    Looking at it and thinking out loud... I suppose the leadscrew assembly could be inverted (motor sitting where pineapple now sits) and a skirt/saddle-type shuttle fashioned to drape down all sides/ends of the carriage. That could allow a much larger range of motion since the leadscrew and guide rods would point upward... etc.

    Not necessary here, though... I'll test what I've got...

    -- David
    Last edited by dkj4linux; Today at 04:16 PM.

  3. #83
    dkj4linux's Avatar
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    Alright... I admit it!

    I'm an old man... and I'm easily amused.

    Way back when... I was paid for my engineering services and CAD was a 2D thing... that's where virtually all my CAD experience was gained. But all this newfangled stuff -- this 3D stuff -- just blows me away!

    I've discovered how to open the McMaster-Carr catalog and download models of their hardware and import it into Onshape. So now I'm playing with Assembly drawings and I'm just discovering how to put things together into a virtual assembly. I'm still really awkward at this point (that'll probably never change at this late date...) but I'm having a blast!

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    Cool!

  4. #84
    Posted a thousand or more times jhitesma's Avatar
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    That McMaster catalog is dangerous in a very good way Though...it's also a little dangerous in a bad way - I've found onshape's performance can start to drag on my computers if I start using too many complex models. So I tend to stick to simpler mockup models instead of the actual part models a lot of times. Like instead of importing an 805 bearing I'll just use a quick sketch/extrusion to show the basic dimensions.

    Which kind of bugs me. I really want to make REALLY detailed models with each ball in a bearing and the seals all modeled...and I know I can. But I'd rather have quicker performance most of the time

    I still get hung up on mates and their relations when I start messing with assemblies. Getting better but much slower than I'm getting better at drawing 2D/3D stuff.

    One of these days I need to go back and re-assemble my egg-bot since it has a lot of nice things to join up and make move
    Stop in and say hi in the unofficial FT IRC channel!

  5. #85

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    Made some changes to my z carriage this morning. Moved the upper bearings to the top, shortened them a bit and stretched the height. Now it really looks like 23mm of travel. I also added a spot for the vinyl cutter/pen holder, but as I am typing this, I realize that the vinyl cutter will not clear the bottom of the needle guide. Whoops. It will still be usable, but the needle and guide will have to come out. I don't know that I'll use it that much. What I want to be able to do is put a pen on it, draw panel lines and other decorations, pull the pen and cut guide holes, flip the board over, put pegs in the guide holes and cut the parts.
    It is printing now. We will see.

    Click image for larger version. 

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