XY Gantry Module for Lum Printer

The Loom printer is a new type of FDM/FFF 3D printer with an unbounded build volume. I developed this proof-of-concept prototype during early 2014 during my residency at Autodesk's Pier 9 to explore larger scale fabrication of mesostructured lattice materials and to attempt to produce finely-structured sheet goods on an architectural scale. The Loom Printer derives its build volume from a non-orthogonal coordinate system that de-couples the assembly plane form the adhesion plane to allow the part-in-progress to exit the machine while still being fabricated.

This Instructable covers the fabrication of the XY gantry module, which is designed to be a stand-alone and easily configurable unit of its own. To build the infiniprinting non-orthogonal Z-axis module and accompanying machine frame, please visit the second instructable in this series.

Full CAD for the project can be downloaded here.

Printed Parts:

All parts can be downloaded below or from the link Thingiverse pages. You will need:

• 1x Drive block parts printed in ABS or PET (other low-profile Replicator 2-compatible drive blocks will likely work as well)
• 1x carriage.stl, printed in ABS or PET
• 1x hot end clamp.stl, printed in ABS or PET
• 2x front pulley idler.stl, printed in PLA or other
• 1x X-axis secondary.stl, printed in PLA or other
• 2x Y-axis constrained shaft mount.stl, printed in PLA or other
• 2x Y-axis compliant shaft mount.stl, printed in PLA or other
• 2x hardstop.stl, printed in PLA or other
• 1x X-axis primary.stl, printed in PLA or other
• 1x terminus stand-off.stl, printed in PLA or other
• 2x cable chain terminus.stl, printed in PLA or other
• 62 cable chain links, file 5x chain links.stl, printed in PLA or other

Nuts, Bolts, Bearings, etc:

• 1x M3 Hex Socket Shoulder Screw, 4mm diameter x 10mm length shoulder
• 1x Compression Spring, 0.360"OD, 0.276"ID, 0.630" Free Length, 32lbs/in spring rate
• 1x M3 x 6mm Flat Head Cap Screw
• 1x Ball Bearing, 4mm ID x 10mm OD x 4mm width
• 2x NEMA 17 stepper motor
• 154" (3.4m) four-conductor wire (cut to two 67"/1700mm lengths for the wiring harness)
• 1x MK7 (or equivalent) drive gear
• 18x M3 hex nuts
• 4x M3 washers
• 7x LM8UU linear bearings
• 1x Makergear hotend (or other groove-mount hotend)

• 6x 20 tooth GT2 timing pulleys
• 2x M3x5mm socket head cap screws (cable chain termination, X-direction)
• 8x M3x6mm socket head cap screws (securing LM8UU linear bearings)
• 8x M3x10mm socket head cap screws (stepper motor mount)
• 10x M3x20mm socket head cap screws (cable chain termination, Y-direction)

• 24x M3x8mm socket head cap screws

• 1x 5mm to 5mm flexible shaft coupler
• 8x 5mm flange bearings, 9mm OD
• 2x 8mmx400mm hardened steel shafts
• 2x 8mmx200mm hardened steel shafts
• 1x 5mmx400mm hardened steel shaft, cut to:
  • 1x 5mmx65mm shaft (X-axis idler block)
  • 1x 5mmx305mm shaft (Y-axis drive shaft)
• 1x 2mmx200mm hardened steel shaft, cut to:
  • 2x 5mmx25mm shafts (Y-axis idlers)
• 80" (2m) GT2 timing belt, 6mm wide, cut to:
  
  • 35.25" (895mm) for the X-axis
  • 21" (533mm) for the Y-axis drive side
  • 19.75" (501mm) for the Y-axis idler side
• 1x 1/4"x18"x24" acrylic sheet
• 1x can of acrylic bonding agent or cement

For the filament drive:

• 1x drive block parts printed in ABS or PET (other low-profile Replicator 2-compatible drive blocks will likely work as well)
• 1x 1x M3 Hex Socket Shoulder Screw, 4mm diameter x 10mm length shoulder
• 1x Compression Spring, 0.360"OD, 0.276"ID, 0.630" length, 32lbs/in spring rate
• 1x M3 x 6mm Flat Head Cap Screw
• 1x Ball Bearing, 4mm ID x 10mm OD x 4mm width
• 1x NEMA 17 stepper motor
• 1v MK7 (or equivalent) drive gear

For the carriage and hotend assembly:

• 8x M3x20mm socket head cap screws
• 6x M3 nuts
• 3x LM8UU linear bearings
• 1x printed carriage in ABS or PET
• 1x printed hotend clamp block in ABS or PET
• 1x Makergear hotend (or other groove-mount hotend)

Tools:

• Ball-tipped 2.5mm hex driver
• Ball-tipped 2.0mm hex driver
• Ball-tipped 1.5mm hex driver

Assembly:

Start by assembling the mechanical drive block. Be careful to align the drive gear with the path of the filament by threading a section of filament through the assembled drive assembly and loosening, then tightening the drive gear set screw to ensure that the groove of the drive teeth is well-aligned. Once the drive block is assembled, slide the LM8UU bearings into the channels in the carriage and secure with the M3 nuts and six M3x20mm screws. Carefully seat the hotend in the matching grooves in the clamp block and the carriage. Secure by passing the remaining M3x two M3x20mm screws through the clamp block and carriage and into the stepper motor.

Materials:

• 1x NEMA 17 stepper motor
• 1x GT2 timing pulley
• 1x printed X-axis primary drive block (PLA or other)
• 2x LM8UU linear bearings
• 1x spacer block (PLA or other)
• 2x cable chain terminations
• 8x M3 nuts
• 2x M3x5mm socket head cap screws (cable chain termination, X-direction)
• 4x M3x6mm socket head cap screws (securing LM8UU linear bearings)
• 4x M3x10mm socket head cap screws (stepper motor mount)
• 2x M3x20mm socket head cap screws (cable chain termination, Y-direction)

Tools:

• Ball-tipped 2.5mm hex driver
• Ball-tipped 1.5mm hex driver

Assembly:

Insert the LM8UU linear bearings into the receiving channels in the drive block and secure using four M3 nuts and the four M3x6mm screws. Next, attached the X-axis cable chain terminus using two M3 nuts and the two M3x5mm screws. Secure the Y-axis cable chain terminus using the spacing block, two M3 nuts, and the two M3x20mm screws. Finally, tighten the pulley on the motor shaft and bolt the motor to the drive block using the four M3x10mm screws. Leave the screws somewhat loose as the motor will be used to tension the X-axis drive belt in later steps.

Materials:

• 4x M3 nuts
• 2x LM8UU linear bearings
• 1x 1 tooth GT2 timing pulley
• 1x 5mmx65mm shaft
• 2x flange bearings
• 1x X-axis idler block
• 4x M3x6mm socket head cap screws

Tools:

• Ball-tipped 2.5mm hex driver

Assembly:

Insert the LM8UU bearings into the channels in the printed idler block and secure using the four M3x6mm screws and nuts. Insert one flange bearing into the rear idler axle guide and slide the other onto the 5mm x 65mm shaft, following it with the GT2 timing pulley. Be sure to orient the pulley to match the pictures above, then insert the shaft through the printed idler block into the second flange bearing. Make sure that both bearings remain properly seated in the printed part.

Materials:

• 35.25" (895mm) GT2 timing belt
• 2x 8mmx400mm hardened steel shafts
• 2x 8mmx200mm hardened steel shafts
• 1x X-drive assembly
• 1x X-idler assembly
• 1x extruder and carriage assembly
• 2x non-compliant shaft mounts
• 2x compliant shaft mounts

Assembly:

Slide the two 400mm rods into the X-idler and then gently slide the carriage onto the rails, being careful not to catch the edge of the shaft on the re-circulating ball bearings within the linear bearings. The nozzle of the extruder should be on the same side of the gantry assembly as the bearings on the X-idler. Next slide the X-drive onto the rods. Press the end of the GT2 belt into the grooved slot on the X-drive side of the carriage and route it over the drive pulley, around the idler pulley, and secure the other end to the second grooved slot on the carriage. Tension the belt by pulling the X-drive motor away from the carriage and tightening its mounting screws when the belt is taught. Carefully slide the 200mm rods through the linear bearings in the X-drive and X-idler. Mount the two non-compliant shaft mounts to the 200mm rod running though the X-drive and mount the two compliant shaft mounts to the 200mm shaft running through the X-idler. Hard stops in the form of collars or printed pieces are best applied to the shafts before the shaft mounts.

Materials:

• 1x 1/4"x18"x14" sheet of acrylic

Tools:

• M3x0.5mm tap
• M6x1.5mm tap

Assembly:

Laser cut all the parts contained in gantry_DXFs.zip. While the frame pieces still have their protective paper coating, tap all the small holes using the M3 tap and tap the larger holes in the corner brace tabs using the M6 tab. Chucking the taps in a hand-held drill expedites the process.

Assemble the frame following the images above, knitting the joints of the four frame panels together and bracing the corners with the small triangles. The assembled gantry can be used at this time to help align the acrylic parts, but a machinist's square should be used to check all the corners before bonding. Once everything is in place, apply acrylic cement to the frame joints from the inside, being sure that it wicks into all surfaces of the joints. I like to use a needle applicator for this step. Note that the gantry can be installed in this step by combining it with the following step.

Materials:

• 16x M3x8mm socket head cap screws

Tools:

• Ball-tipped 2.5mm hex driver

Assembly:

Cover the nozzle of the extruder with several layers of tape or remove the hotend from the carriage to prevent any damage during assembly. Position the frame so that is standing on the front face and then carefully slide in the gantry. Use the M3x8mm screws to secure the shaft mounts to the rear of the frame (the part standing in the air). With those secured, gently rotate the frame to stand on one of its shorter sides and secure the two remaining shaft mounts to the front face of the frame. Be sure that the compliant mounts are oriented so that the air gaps are in-plane with the gantry. These shaft mounts constrain the shaft in the Z- and Y-directions, but allow for a slight amount of compliance in the X-direction to avoid binding.

Front Y-Belt Idler Block Assembly:

• 2x 18 tooth GT2 timing pulleys
• 4x flange bearings
• 2x 5mmx25mm shafts
• 8x M3x8mm socket head cap screws
• 2x printed idler blocks

Additional Y-axis Materials:

• 21" (533mm) GT2 timing belt (primary drive side)
• 19.75" (502mm) GT2 timing belt (secondary drive side)
• Rear Y-axis idler block
• 2x flange bearings
• 1x NEMA 17 stepper
• 4x M3x10mm socket head cap screws
• 4x M3 washers
• 1x GT2 18 tooth timing pulley
• 1x 5mmxXXXXmm shaft
• 1x 5mm-to-5mm shaft coupler

Assembly:

Assemble the Y-axis idlers and install the printed components on the front of the laser-cut frame using the M3x8mm screws. Install the rear Y-axis drive shaft support, making sure to align it with the laser cut port in the frame. Assembly the Y-drive shaft by mounting the 5mmx296mm rod to one side of the stepper motor and securing the timing pulley to the other. On the far end of the 5mmx296mm shaft, slide on a flange bearing followed by a timing pulley followed by a second flange bearing, both with flanges facing away from the pulley. Use the four M3x10mm screws and washers to secure the stepper motor to its mounting bracket as illustrated in the pictures. Center the motor on the slots, tighten it down temporarily, and then align the flange bearings and pulley on the end of the drive shaft. Once aligned, tighten the pulley set screws.

Press one end of the 21" (533mm) section of belt into the grooved slot on the pulley side of the X-drive block and thread the belt out through the slot in the rear of the frame, around the Y-axis drive pulley, and back through the frame. Stretch it across the frame and out through the second slot and position one of the Y-idler pulley assemblies under the belt before returning the belt in through the slot and anchoring it in the second grooved slot in the X-drive block. Align the X-gantry to be square to the frame, either using a square or a piece of stock material of consistent width. Repeat the belt-routing process on the other side of the frame with the 19.75" (502mm) length of belt.

Materials:

• 2x 67" (1.7m) lengths of four-conductor wire
• 62x printed cable chain links (37 for X-axis, 25 for y-axis)
• Hotend connectors from hotend kit

Assembly:

Thread your cables through the two lengths of assembled cable chain. The extruder-end of the cable harness should end with the two wings of the final cable chain link so that it can clip onto the terminal block on the carriage. Crimp the connectors onto the heater and thermistor lines for the hotend and likewise for the stepper motor. Clip the extruder-side of the X-segment of the cable harness onto the carriage and clip the other end to the terminal block on the X-axis drive block. Clip the Y-axis segment of the cable harness to the X-axis drive block and route to the back of the gantry, near the Y-axis motor. Zip-tie the Y-axis last chain link to it's terminal block on the X-axis drive block and then zip-tie the X-axis motor lead to the side of the Y-axis cable chain. Trim zip-ties when done.

Using a controller board and firmware of your choice, boot up and run the gantry for 3D printing applications, research, or automation projects.

To continue to the second part of the Lum Printer Project, the rotary Z-axis and belt, visit this instrauctable.