LINEAR RAIL SPHINX 55 (Blue OX plates)

My machine is a combination of the following;

Based on Sphinx 55 by Kyo Shinohara link
Inspired by Sorin Iliesu build link
Custom plates from Chris Laidlaw - Blue OX link

For the rails I used the following;

6 - 500mm MGN12 linear rails
2 – 250mm MGN12 linear rails
16 – MGN12H guide blocks​

To attach the rails I used;

58 10mm M3 scoket head for mgn12 blocks
6 8mm M3 scoket head for x/z-axis plate mgn12 blocks
140 8mm M3 scoket head for mgn12 rail to c-beams
140 M3 t-nut for attaching rails
8 34mm M5 scoket head for anti backlash blocks with spacers
24 20mm M5 button head for plate to end of extrusion ie plate to end of c-beam
8 30mm M5 button head for thicker plate end connection on z axis
16 10mm M5 button head for 6mm plate to t-nut/slot connection

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Openbuilds has great instructions for the Sphinx 55, so I thought I would just document the things that I did differently to add the MGN12 linear rails.

My 500mm rails were just a bit long I had to grind of about 1mm to make them fit between the end-plates on the c-beams.

I used the slide in style t-nuts for the rails, I did not trust the twist in style with so many to fiddle with.



To attach and align the rails I made a small alignment jig that I attached to the c-beams to get the first rail of a pair of aligned to the c-beam. I worked my way front to back snugging the jig down then setting the rails against it and tightening down the rail bolts.


With the first rail aligned to the c-beam, I then checked the rails with an indicator. However using the jig was enough to get the first rails straight, so using the indicator may not be necessary. Once I had the first rail straight and fixed in place I loosely installed the second with the guide blocks and end-plate. That way I could slide the end-plate to align the bearings and then sung everything up.



The front plate on the y axis c-beam will allow the side rail blocks to slide right off the front, for now I installed a few longer screw and nuts for a stop. I know that I will have to work out a better solution than this when I start to run the machine.


I found that I was not happy with the standard locking collars and decided to look for something that fit a little more snugly. I found 5/16 double split shaft collars on ebay and they fit the openbuilds rod very well. Here is a link. I also placed a thrust bearing between the flexible coupling and the c-beam end plate. My theory is that this arrangement will help eliminate unwanted movement.



The stock limit switch locations were not compatible with my linear rail build. After a bit of thought I decided that inductive limit switches would be better with the locations that I had to work with. I cut an aluminum angle bracket for the z limit and mounted it to the z axis c-beam.



The x-axis limit switch is mounted to a 3d printed bracket that attaches to the x-axis c-beam.



The y-axis limit switch is mounted to a 3d printed bracket that attaches to the y-axis motor stand.



I am up and running now so I am calling this build complete. All-though I still have quite a few things I want to do, like build and sound/dust enclosure with a box for all of the wiring and electronics.



Here are a few of the first things I have cut with the machine.

A set of front c-beam plates to prevent the y-axis from traveling to far forward.


A set of 'nuts' to make adjusting the tension on the x-axis motor easier.


And a set of spindle mount brackets to strengthen the spindle mount and make adjusting it easier. Here are links to the files for this BRACKET and CAM FILE