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Sphinx anti backlash nuts

Discussion in 'CNC Mills/Routers' started by Andreas Bockert, Oct 23, 2017.

  1. Andreas Bockert

    Andreas Bockert Journeyman
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    Hi

    I’m trying to build my first CNC based on the Sphinx design. The first difficulty I encountered was with the anti backlash nuts.

    I’ve played around with a few of them. When I tighten them enough to take out the play it is impossible to insert the screw from the “narrow” side. Is this expected? It would make it hard to mount in Sphinx-style since they’re mounted back to back. I haven’t found any resources on how to set up the AB nuts.

    Also, it seems t be very tight when screwing the onto the plates. It’s hard to turn by hand. Is the alignment of
    The threads on the AB-nut guaranteed? If one starts a quarter of a turn differently nothing will align.

    How much would you lose by only having 1 AB nut?

    Thankful for any help!

    Best regards,
    Andreas
     
  2. ChadRat6458

    ChadRat6458 Journeyman
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    I ran into the same issue. The plans are misleading. For the Y-axis plates, use 1 anti back lash nut or 2 regular nuts. If you try 2 anti back lash nuts then it won't work.
     
  3. Mark Carew

    Mark Carew OpenBuilds Team
    Staff Member Moderator Resident Builder Project Maker Builder

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    Hi @Andreas Bockert You really should only need on anti backlash nut block on this setup (I put mine on the center set of holes) I think the option was there if perhaps you wanted to use two standard nut blocks in stead. The guy to ask on this one would be @Kyo I am sure he would be happy to explain it for you.
    Hope this helps.
    Mark
     
    Kyo likes this.
  4. Kyo

    Kyo Master
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    Hello @Andreas Bockert
    Welcome to the community. Feel free to post up your build we love photos and build logs. :thumbsup:

    @Mark Carew is correct, while two anti-backlash nuts can indeed be fitted on V2 and newer plate revisions, you only need one. I originally intended to run dual anti-backlash nuts myself but later found it to be unnecessary. However the additional nut mounting points remained in the design and are to give the builder more options when choosing nuts. Center mounting point is used when running a anti-backlash nut. The two outside mounting holes allow you to run dual nuts. Running dual nuts can have similar results as running a single anti-backlash nut. My original build used a single anti-backlash nut on all axis. This worked out very well.

    Also make sure when mounting either nut option to the plates to not over tighten. To much force when securing them can result in deformation making the screw "tight" or "difficult" to turn.
     
  5. Andreas Bockert

    Andreas Bockert Journeyman
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    Thank you for the responses.

    I had a problem with the AB nut catching when entering the threads on the other side of the slit. What I did was to slightly compress the gap by hand which allowed the rod to enter the threads. Then while screwing the lead screw in and out of the entry of that thread I let go of the compression. This way the lead screw cut away the part of the thread that was catching. The same technique was useful when the thread was catching after applying tension with the set screw as well.

    I managed to mount both backlash nuts without them binding too badly. I set both of the as loose as possible (at this point both had a lot of slack). When I tightened the screws the skewed a bit and applied tension to the rod. No backless was present at all.

    @ChadRat6458, @Mark Carew & @Kyo. After reading your responses I decided to go back and convert it to a single AB nut. In the spirit of keeping things simple.

    Thank you for your input.

    /Andreas
     
  6. patdee

    patdee Well-Known
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    Hi Kyo,

    I was watching your video of the "Sphinx" CNC build last night; and I notice that you recommended the "shorter" X axis end plates. Yet I see many who use the 2" higher end plates. IE: Like the one Michael built.

    I am strongly leaning towards building your Sphinx CNC. Do you still recommend the shorter plates that you designed? Please be candid. I want no flexing and I know you understand. So I am just before ordering either "set" of plates from Chris. I have great respect for what you have done; and I need your input straight out.

    Thanks so much Kyo for your time,

    pat
     
  7. Kyo

    Kyo Master
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    Hello @patdee
    I do recommend the shorter plate set from Chris "Here" Keeping the X-axis as short and close to the work surface as you can get away with really does help. But it comes down to what you will be cutting. I mostly cut hardwood , aluminium ect. so clearance was not to much of a problem and when it was, I removed the spoiler board to gain extra space. However for some projects the standard plate set may not offer enough clearance and if you focus more on foam , plastic , softwoods either set will work for you.
     
  8. patdee

    patdee Well-Known
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    Thanks so much Kyo.

    That is precisely what I need. And since I will intend to do MUCH cutting of aluminum with various thicknesses; I shall order the shorter plates.

    Thanks again. You are now my mentor when it comes to CNC. I thank HIM for you friend,

    pat
     
  9. Andreas Bockert

    Andreas Bockert Journeyman
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    For maximum rigidity you probably want to go with chris’s me modifiied z plates that use full sized wheels on the outside. You would need to update your BOM accordingly and it will add a bit of cost to your build.
     
  10. patdee

    patdee Well-Known
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    Yes I have already budgeted for that. But thanks for reminding me.

    By the way, and at the risk of my seeming to be an "Idiot", what in the pluperfect hallelujah is "BOM". Been seeing that on OpenBuilds forums and I cant decipher it. Help! IE:

    Kin yuz hep an ole has-been; that shouduv been in the grave long ago? LOL
     
    #10 patdee, Nov 7, 2017
    Last edited: Nov 7, 2017
  11. Andreas Bockert

    Andreas Bockert Journeyman
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    BOM - bill of materials

    Lots of things to learn when embarking on an adventure like this.
     
  12. patdee

    patdee Well-Known
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    WOW!

    Talk about being a moron!

    Wow.

    Oh well I'm happy! Some aint! Praise His holy name.
     
    dixiedee likes this.

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