T8 and M8 rod centrers for Dagoma DiscoEasy and DiscoVery

This is a remix of the following tracks:

• High centres with bearings and reinforcements: https://www.thingiverse.com/thing:2538950

• XYZ anti-waviness of the 5x8 flexible coupler: https://www.thingiverse.com/thing:2537196

This remix was made to allow the use of T8 Trapezoidal screws,

by implementing long guide bearings with integrated clamps.

These bearings also allow the use of M8 threaded rods. They then bring a much better guidance than the original parts I had previously shared.

The clamps integrated in the bearings allow to suppress all vibrations of the rods, to stiffen the structure and to distribute the weight of the mobile assembly in Z so that it is no longer supported only by the motor mountings. This allows a real gain in stability, reproducibility and precision (see pictures n°6 & 7).

When using the 3-fan head, the stroke Z is increased to 220 mm thanks to the high centring pins.

The centering parts in connection with the rod require the use of these carriages or their remix: https://www.thingiverse.com/thing:2627287

<All the centerfolds up.

• 4 x screws M3 - 10 (clamping horizontal rods)

• 14 x screw M3 - 12

• 4 x M3 washers

• 18 x M3 nuts

• 2x KFL bearings for flat mounting: 8 mm (1st choice) : https://www.banggood.com/810121517mm-Bore-Diameter-Zinc-Alloy-Pillow-Block-Flange-Bearing-KFL-Series-p-1119328.html

(XYZ anti-waviness of the 5x8 soft coupler)

• 4 x screws M3 - 12

• 4 x screws M3 - 18 (or longer, for fixing the bearing)

• 4 x M3 washers

• 8 x M3 nuts

• 2x KP bearings for side mounting KP08 (3rd choice) : https://www.banggood.com/8mm-to-35mm-KP-Series-Bore-Diameter-Mounted-Ball-Bearings-Zinc-Alloy-Pillow-Block-Housing-p-1076413.html

• useful length 320 mm (or more)

• For information, I use 2x ground T8 trapezoidal rods of 400 mm (cuttable at 320 mm or by increasing up to 445 mm the 4 rods of the structure Z), having the following reference. This part number includes KP08 bearings for side mounting, as well as precision couplings: https://www.banggood.com/T8-400mm-Stainless-Steel-Lead-Screw-Set-with-Mounted-Ball-Bearing-and-Shaft-Coupling-p-995052.html

Instructions for a good assembly:

<Before the assembly:

• Loosen (without completely unscrewing the fasteners of the 2 Z motors)

• Slacken the belt from the X-axis

• If using trapezoidal rods, loosen the fasteners on the carriage nuts slightly to release them.

Instructions for mounting :

• Pre-assemble all the parts by not fully tightening the bearing fixing screws KFL (top) and KP (bottom) in order to free them. They will be retightened later.

• Mount the rods (trapezoidal or M8) last, sliding them from above into the (loose) couplings through the nuts of the Z

• Lift manually (by rotating the rods) the 2 Z carriages to an average height (approx. Z= 150 mm). If there is a horizontal play in the X rods, make sure to use shims to eliminate this play. Then re-tension the belt X. Move (manually raise/lower) the carriages Z to check that the bearings slide properly.

• Lower the Z-carts to the lowest point. In this position, first tighten the bearing fixing screws KP (bottom). Then, if you have trapezoidal rods, tighten the fixing screws of the trapezoidal nuts. And finally, tighten the small screws (headless) in the center of the KP bearings.

• Lift the Z carriages to their maximum stroke (always by manually turning the Z rods). In this position, tighten the fixing screws of the KFL bearings (from the top), then tighten the grub screws in the centre of these bearings.

• Manually lower the Z carriages, tighten the couplings. Then - and lastly - retighten the motor fastening screws.

Supports: yes

Infill: 30%.

Resolution :

• 200 um for the low centerers,

• 100 um or 150 um for high centring devices, + supports

Wall thickness: 1.2 mm