I am planning to do some major updates to my SO3, since I was unhappy about my Z axis from 2015. Right now I have bought 2 600mm MGN20 rails to eliminate the X axis v-wheels, and a 100mm travel ball-spindle assembly (similar but chunkier than the C3D model currently in the store). has anybody done these or similar updates to their machine, and can share some thoughts and learning experiences, before I start ripping the machine apart for the new build?
There’s VinceFab whose done most things to most Shapeoko and Nomad, check his posts.
Dan Story’s upgrade is a good place to start;
He very kindly posted all the CAD files on thingiverse too.
This thread makes a few small changes…
This thread has a write up and pictures of implementing Dan Story’s rail upgrade
This is a fantastic overview about some of the other upgrades done already… so glad to see I am on the right track.
First question: The projects show the Z axis assembly on 4 rail blocks. My current design is just using 2, optimizing the machine for x travel, since I am loosing 30-50mm y travel. i feel the load bearing on 2 blocks from x travel skew should be sufficient (my z assembly is 89mm wide, and the spindle holder is 120mm wide), and I am uncertain if 4 blocks would do much better than 2 blocks in regards to y travel skew.
What I did on my Nomad is use shorter blocks so that I could double up on them. I went for 2x40.3mm blocks, which gave me a bit over double the moment rating I would have had for a single longer block.
I used 15mm rails rather than 20mm rails though. 20mm rails look appealing and I could have made them fit but someone pointed out to me that you want the thing the rails are attached to to be stronger than the rails. If the rails are stronger than the mounting surface (which I’m a bit concerned is the case for you), rather than the mounting surface flattening the rails (which is what is meant to happen), the rails will bend the mounting surface (and therefore not be flat, which is bad for longevity and accuracy).
How much a problem this is in reality, I have no clue.
Why not just copy what C3D did with the Pro.
Personally I would ditch the round shaft rails on the Z and run 15mm square profile. 4 blocks on each Axis, if you’re gonna build it then why not overbuild it a little. Also, try to get your spindle as close to your X axis as possible to minimize leverage.
20s for the x is interesting, how good is the movement? If you flip your motor plates you’ll get some Y travel back.
It isn’t so much “ditch the round shaft rails” - I have them, paid money for it, might as well use them. The unit I got was interesting due to the integrated 5mm pitch ball shaft. it turned out to be heavier than i liked, and I am concerned about the stickout… on the other hand, it will be a 1000% improvement over what i have right now?
the 20mm rails was also a “looked good when I bought it”, we’ll see how well they run. I think it will be adding to the structural integrity of the cross beam. i can check the flatness of both the beam and the rails before i install them to see who will bend who.
flipping the plates is a splendid idea, thanks so much for it
I have another general question, and I haven’t seen this version yet: I am going to ditch the belt drive for the X axis as well, my linear rails came with a ball screw. At the moment I have planned to put both linear rails on the front of the extrusion, but if i put one on the front, and the other on the top, do I get a slightly better stiffness (as well as a bit more Z travel) out of the system?
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