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Trouble with Xtreme Wheels

Discussion in 'General Talk' started by Anton, Oct 15, 2015.

  1. Anton

    Anton New
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    Hello! When I assembled OX CNC and put gantries on rails, small scratches and nicks appeared on wheels. I think, it happened because edges of the rails were not sanded. Should I buy a new wheels, or it will not affect to the work of the machine?
    upload_2015-10-15_8-37-11.png
    upload_2015-10-15_8-37-44.png
    upload_2015-10-15_8-38-18.png
     
  2. Ronald van Arkel

    Staff Member Resident Builder Builder

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    Hello Anton,

    Just use those wheels as they are. If they break you can always replace them. It will not affect much of the precision, if at all.

    -Ronald
     
  3. Joe Santarsiero

    Joe Santarsiero OB addict
    Staff Member Moderator Builder

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    How do they feel when they roll on the track? If you can feel a bumping then it may translate to a cut.
    Personally and if this were the case, I might hit the spots with a light flame then roll them in the track while hot. Do this at your own risk though.
     
  4. Ronald van Arkel

    Staff Member Resident Builder Builder

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    Bumping also may indicate over-pressure on the bearings by the way.

    -Ronald
     
  5. R_B

    R_B Journeyman
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    I also have some similar scratches/nicks/cuts/imperfections in a few wheels.
    Hard to believe it happened during assembly and I have certainly not run them over any metal.
    Not YET, I am still not milling metal.

    What I find disturbing is that they either came this way (indicating a q.c. problem) or they are SO fragile that they are susceptible to damage from bumps that I haven't even felt when assembling them.
    Either way, it is disturbing.
    I am unable to say if they affect the tool path, although I can detect a little roughness when hand jogging - by which I mean turning the lead screws by hand, not "manual jogging" with grbl panel's controls.

    If they are this delicate there WILL be problems if/when an aluminum chip gets in the way - e.g. if it embeds in the wheel.
     
  6. Ronald van Arkel

    Staff Member Resident Builder Builder

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    R,

    What is shown on the picture above is most likely due to eccentric spacers not being set to give the most space between wheels, that and pushing the assembly on the V-Slot. Most of us have learned it the hard way while we were enthusiast to get the build together. V-Slot/C-Beam edges are real sharp at the end where they are cut. It is most defiantly not a QC problem although some dents can happen when they are shipped with the bearings and shims in the same bag and got banged together with some NEMA23 while being shipped. I've not seen any negative effect of scratches and small dents in the wheels. The damage is on the surface and will not affect the main structure of the wheel. The scratches most likely will be pushed flat when you start to use the machine. When you design a machine than make sure chips can't get into the tracks, or at least as less as possible. Filling up V-Slot or C-Beam with plastic or foam strips do help when cleaning the machine after every cut.

    -Ronald
     
  7. R_B

    R_B Journeyman
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    I agree that the second picture showing symmetrical cuts in this pattern '\ ____ /' could well be from pushing the wheels onto the end of a sharply cut section of channel.
    There is no warning in the build videos that I have watched, in fact the one for the C_Beam plate maker shows at least one of the carriers being adjusted a few times when OFF the channel and then being tried for fit ON the channel, i.e. it suggests that this is the "proper" way to adjust the eccentrics.
    If this is the case and if the wheels suffer as a result then we should be advised to smooth the edges of the ends, or perhaps to tape over them.
    Right now I am not remembering whether the video shows the Z-axis "internal" wheels being adjusted this way - though I don't think I can access the eccentrics with the carrier IN the channel.

    I always TRY to keep chips where they belong, but... well, machining IS machining, chips WILL find their way to exactly the wrong places. Not IF, but WHEN.
    Several folk worry about chips betting as far as the power supply and logic board, I don't think it a stretch to say that even the most careful of us will get chips into these wheels at some point.

    {Edit - I just looked, the Z-axis carrier wheels are "internal" in the extrusion and the eccentrics are just about impossible to adjust insittu. Almost certainly the one that is shown in the video as being adjusted out of the rail and tried for fit (repeatedly) until "right, but not too tight" not a quote.}
     
    #7 R_B, Oct 16, 2015
    Last edited: Oct 16, 2015
  8. Ronald van Arkel

    Staff Member Resident Builder Builder

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    Hello R,

    All of the picture show the same thing, but yes, the second picture is a bit more obvious about what happened. I do agree that a warning is in place and for my last build, the Routy 290, I made a whole building manual that includes some tips on building. Those tips can be applied to every build you start. I'm planning on making more manuals in the near future including the C-beam actuator.

    Chips indeed do tend to jump and bounce all over the place but the damage to the wheels is minimum and will most likely have no effect on the cutting you will do. I's just one of the limits of using V-Slot or C-Beam, OpenRail might be a better option there.

    Still, I believe V-Slot is one of the best things I've come across to build your home-build CNC machine. Industrial linear real is way more expensive and you can buy a lot of V-Slot and wheels for the same price. Not for nothing that I started to distribute V-Slot in Mexico :).

    I saw some people building boxes around their wheels and also use brushes to clean the linear guide before the wheels roll over. To bad they don't sell those "door-brushes" (to keep dust, insects and wind from entering underneath the door) here in Mexico, but the have them in Europe an very possible in the USA/Canada as well.

    -Ronald
     
  9. R_B

    R_B Journeyman
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    Thanks for the idea on brushes, I will look into some possibilities for sweeping/wiping ahead.
    On the C-Beam plate maker it shouldn't be TOO bad - the X-axis wheels are quite high on the gantry above the cutting surface, the Y-axis wheels are already covered with the plate, the Z-axis ones are internal so tricky to get at - very hard to get at to wipe manually.
    That said, "stuff" happens and chips DO get to what appear to be the most unlikely places, so it is probably worth some work to do what I can to keep them away from the wheels.
    {Edit: Thinking through this a bit more, I can probably figure a way to use short lengths of car wiper blades for this - in US we would call this squeegeeing (spelling ?) Anyway, it seems like a readily available low cost source - used ones might work too }
     
    #9 R_B, Oct 19, 2015
    Last edited: Oct 19, 2015

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