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Baja i3 Rework Y axis Assembly

From Roaddog Labs Docs

Introduction | Bill of Materials | Y-axis Assembly | X-axis Assembly | Connecting X-axis and Z-axis | Motor Installation | X and Y-Axis Motion | Heated Bed Assembly | Extruder Installation | Electronics and Wiring | Firmware Configuration | Validation and Testing | Working with Files and Printing

Heated bed mount

Print bed mount.

Needed parts :

  • Print Bed Plate
  • Y Belt Holder
  • 3x Linear bearing LM8UU
  • 2x M3x14 mm screw
  • 2x M3 washer
  • 2x M3 nut


Mount the Y Belt Holder with two M3x14 mm screws, two M3 washers and two M3 nuts. Y Belt Holder orientation doesn’t matter. You may need to trim the ends of the screws if they interfere with the bottom of the heated bed. You'll know this when it comes time to add the heated bed.

The bearings lay in each of the slots of the print bed plate as shown in the rendering. Zip tie the bearings to the bed but don't completely tighten them down. Just snug for now. Save the final tightening for when you mount the bed to the rods so there is no binding in the motion. If you tighten them too much beforehand they may not be straight and lead to binding.

Y Axis Cross Rods

Needed parts :

  • 4 x Y Corner
  • Y Idler
  • Y Motor Mount
  • 1 x 608zz Bearing
  • 3 x Threaded rod M10x210 mm
  • 1 x Threaded rod M10x360 mm
  • 22 x M10 nut
  • 22 x M10 washer
  • 1 x M8x30 mm hex cap screw
  • 1 x M8 nut
  • 2 x M8 washer
  • 1 x M4x20 mm screw
  • 1 x M4 nut



Step 1

Y Idler assembly: place an M4 nut inside the idler as shown and secure it with a M4x20 mm screw. The M4 screw will be used to tension the belt. If the nut is difficult to get into the nut trap you can trim some of the plastic or you can use a heat gun (or hair dryer) to soften the material and use small pliers to insert the nut. Insert a 608 ball bearing into the groove and slide the M8x30 mm screw with two M8 washers (one each side) and an M8 nut. At this point all the fasteners should be finger tight, just enough to hold them in place. This gives us some flexibility in the assembly and later in the build as things come together you can tighten them for the finished assembly.

Y Idler assembly.

Step 2

Slide the Y Idler assembly to the middle of a M10x210 mm threaded rod. Thread an M10 washer and nut to each side of the idler. Finger tighten. At each end of the rod thread a nut and washer as show at about 30 mm from each end. On a second M10x210 threaded rod thread the nuts and washers from the end as on the other rod.

Y Idler assembly with threaded rod M10x210 mm.

Step 3

This step is different from a regular Rework in that there is a longer upper rear cross rod. This longer rod will be used to tie the melamine frame uprights to the rod frame. Slide the remaining M10x210 threaded rod through the bottom of the Y motor mount as shown in the rendering. Take the single M10x360 threaded rod (it's almost the same length as the longer rods, check to be sure it's the right one) and slide that through the upper Y Motor rod hole. The motor mount eventually will be off center, to the left side of the machine. For now thread an M10 washer and nut on each side of the motor mount, snug finger tight. You'll be moving this to adjust the alignment of the belt later in the build. On the bottom rod only on each end thread a nut and washer about 30 mm from each end. On the longer top rod, thread a nut and washer on each end but line them up so they are in line with the nuts and washers on the lower rod.

Here is what the rear rod set should look like

Rear rod comparison, notice how the top rod is longer.
This is only to show how the mount mount is fastened. The top rod will be longer as show in the previous pic.

Step 4

Take the Y idler assembly you made in step 1 and add a Y corner to each end. Secure the Y corner with an M10 nut and washer, finger tight. Do the same with the Y Motor assembly with two Y Corners. Secure each Y corner with an M10 nut and washer. ON the top rod there will be quite a bit more extending out on each side. The distance between the Y corners should be about 186 mm. Rough it in now finger tight, we'll secure it when we add the frame. At this point see that the rod frame is relatively square and not twisted end to end.

Cross rod assemblies, note that the upper motor mount rod will be longer than shown in the rendering.

Y Motion and Frame Assembly

Needed parts :

  • Heated bed mount assembly
  • Both cross rod assemblies
  • 2 x Smooth rod M8x350 mm
  • 2 x Threaded rod M10x380 mm
  • 12 x M10 nut
  • 12 x M10 washer


Step 1

Take the remaining two M10x380 threaded rods and thread two M10 washers and two M10 nuts toward the middle of the rod, about a third or so (need firm dim) up the rod. This will attach the main frame to the rod frame. Thread an M10 nut and washer about 32 mm on both ends as with the cross rod assemblies.

Y frame rods

Step 2

Join the Y frame rods to the motor cross rod assembly only at this time, snug finger tight. The set of nuts and washers for the frame attachment should be closer to the motor mount cross rod assembly. We'll need to slide the bed on before we join the other cross rod assembly to finish the rod frame.


Overview of Step 2
Axe-Y-sans-chariot-3.jpg


Step 3

Insert each M8x350 smooth rods in the top slots in each Y Corner. Use car not to crack the Y corner when you insert the rod. You may need to trim some plastic or use heat to fit the smooth rod into the slot. Slide the completed bed assembly onto the smooth rods. It doesn't matter which side has the two bearing or the single bearing.

Ready for the bed assembly.

Step 4

Join the idler cross rod assembly to complete the rod frame assembly. As in the previous steps, secure the Y corners with M10 nuts and washers. snug finger tight. At this point insure the bed travels smoothly along the rods. Feel for any grinding or excessive tension on the bearings. If you slide the bed back and forth a few times the bearings will settle into the zip ties. At that point fully tighten the zip ties and cut the remaining tail away. There may be a bit of resistance when the bed glides due to bearing seals, etc. What we want to watch for are grinds and binds. There are slits on each Y corner for securing the smooth rods to the each corner.

At this point we are ready to tighten the main frame. Make sure the frame is on a relatively flat surface. All four corners should touch the surface. Tighten the Y corner bolts in a diagonal manner to insure the frame doesn't twist or bend, and make sure as you tighten the corners the bed is still able to move freely. It may take a couple of attempts to get it just right. Keep the cross spacing between the TY corners at about 186 mm. When complete all four corners should be on the same surface and not rock. Don't tighten the motor mount or idler mount nuts yet, we still need to move them around to align the belts.

Completed rod frame and bed.