X/Y "stiffness" on centre assembly.

New Home Forum Troubleshooting X/Y "stiffness" on centre assembly.

This topic contains 10 replies, has 2 voices, and was last updated by Profile photo of vicious1 vicious1 2 months, 3 weeks ago.

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  • #17901
    Profile photo of Nate
    Nate
    Participant

    So I’ve hit the assembly stage, and I’ve noticed that one of my axes is a little stiff going through the centre assembly. It moves, mostly smoothly, but it takes a little bit of a “push” to get it going. I’ve loosened off the Tension A bolt a bit on the relevant axis and it’s helped a bit, but it’s still a bit stiff at first.

    Is this ok? If I can move it by hand I’d imagine that a pair of reasonably high-torque motors could do it too – it’s not like I have to really put my elbow/shoulder into it to get it to move.

    If not, what can be done to rectify it, or will it just correct over time?

    25mm OD international version, btw, using 3mm wall thickness aluminium extrusion.

    #17902
    Profile photo of vicious1
    vicious1
    Keymaster

    A snug axis is fine, but aluminum tubing will not work. Soft steel doesn’t work. You will wear groves in that aluminum very quickly and you will have a loose inaccurate axis in a few hours of use. Sorry

    #17906
    Profile photo of Nate
    Nate
    Participant

    I’ve read testimonials on this very website stating the exact contrary re the “softness” of the material.

    With that said, if it comes to that I’ll just find a steel supplier locally that’s willing to sell to a “little guy”. What steel type would you recommend for the rails?

    #17907
    Profile photo of vicious1
    vicious1
    Keymaster

    Where have you seen that aluminum is fine?

    The most common material is Steel EMT conduit. Unfortunately some brands are too soft. I had a set of rails wear out in a few hours of 3D printing, very minimal loading. I have tried everything I can get my hands on in the last year and a half.

    You shouldn’t need a steel supplier, most countries have steel conduit, sold at a hardware store. Some don’t if you are in one of those countries there are lots of threads on specific suppliers, Australia seems to be the most difficult.

    #17909
    Profile photo of vicious1
    vicious1
    Keymaster

    If you can’t find Any Steel emt Look for Stainless steel tubing, with an OD that matches the printed parts, 25mm, or 1″. With a wall thickness of approx .049″ (more is not better, it adds significant mass vs added rigidity).

    #17910
    Profile photo of Nate
    Nate
    Participant

    Re: things being more difficult to find in Australia; guess where I live.

    IIRC it was actually in a thread about finding stuff in Australia, someone namedropped Ullrich aluminium as a source of the same tubing I’m using, although I got mine from Capral instead.

    #17911
    Profile photo of Nate
    Nate
    Participant

    After some digging I found the post I mentioned.

    You made it.

    Australian tube options

    And I bought aluminium extrusion based on that post. You said, and I quote:

    “Aluminum Tube should be fine with enough wall thickness.”

    Are you now telling me that aluminium isn’t good enough? Because I dropped $100 on aluminium on YOUR ADVICE.

    #17913
    Profile photo of Nate
    Nate
    Participant

    Someone in that thread – the guy that mentioned Ullrich – also says he’s been using aluminium for a while and it’s more rigid than steel, and he hasn’t noticed any kind of “grooving” in the rails.

    -edit-

    Oh look, someone here, using 6061 25mm od aluminium tubing (same as mine) and reporting MINIMAL WEAR after some time.

    MPCNC Version 2 -opinions-

    #17916
    Profile photo of vicious1
    vicious1
    Keymaster

    I am here to try and help you….for free.

    I’m sorry if your pissed that you think I recommended that you should buy aluminum. That reply is over a year old the machine has gone through several major revisions since. In those comments we are discussing how to make this work for Australia (different bearings, eccentric washers, bearing sleeves, ect). In those early comments I am clearly saying “might”, and “should” no one had tried it at that point.

    When we realized aluminum didn’t work, I made a whole new machine! I made the 25.4mm machine because that was a more common size in Australia, to do that I had to redesign the other two as well so all the tool holders would be compatible. That was a 6 month process.

    You already bought your tube, you found a comment that says it works. Try it. It might work for you, everyone uses their machine differently. I can tell you now, a year after that comment and me and several other find aluminum does not work in the long term with the new more rigid design for the accuracy we want. The bearing load is much higher now, the machine is ridiculously more rigid than it was in the beginning (as well as faster to print, less parts, easier to assemble, more square, and universal tool mounts). You have to consider what the machine is being used for, I rarely print with any of mine any more and use them for routing now, my steel rails take a beating and shows signs of wear after 8 months or so of use, my stainless rails don’t show much at all.

    I’m doing my best to help you out and really don’t appreciate negative attitudes for a complete system that is available for free. If you bought something from me please feel free to return it for a full refund. I’d prefer to keep the negativity out of the forums here.

    #17923
    Profile photo of Nate
    Nate
    Participant

    Yeah, well, when I find multiple posts by the creator of the thing saying “yeah aluminium’s fine” only to be quite bluntly told by the same person that not only isn’t it, but they don’t even RECALL mentioning it, I’m going to get a little irritable. You can’t begrudge me backing up my argument with evidence that YOU ASKED FOR so please don’t try. Additionally a lot of those “aluminium is fine” posts are months apart, more than enough time to find any problems, which have apparently gone totally unmentioned.

    Sorry if my attempts to get a straight story and crystal clarity on something that’s cost me a fair bit of time, money and effort are offensive to you.

    #17928
    Profile photo of vicious1
    vicious1
    Keymaster

    Please, I never said it worked, you are now quoting other people, not me.

    You have the aluminum, you are arguing my opinion (just my opinion). The machine will function with aluminum tubing, in my oppinion it will not hold up in the long term.

    This is very simple at this point, try it. Tell us how it goes, maybe I am completely wrong, maybe I got crap aluminum when I tried it. This is a DIY project, do it yourself and see. No harm done if it works.

    Please join the community here without an attitude, everybody here is super cool all kinds of cool things happening both in hardware and software, all for free.

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