MendelMax for LM8UU Assembly Guide

Copyleft © 2012 by Terawatt Industries.

Creative Commons License
Terawatt Industries' MendelMax 1.5 for LM8UU Assembly Guide is licensed under a Creative Commons Attribution-ShareAlike 3.0 Unported License.

Introduction

Welcome to the world of 3D Printing with the MendelMax 1.5 RepRap 3D Printer! The Terawatt Industries MendelMax 1.5 for LM8UU 3D Printer ships as partial and complete kits and can manufacture parts in PLA and ABS (and more with modification). This assembly guide will show you how to build one of our printers, step-by-step.

If you're already familiar 3D printing you may wish to skip to the third section titled Assembling the Gantry

RepRap 3D Printers can create 3D objects from plastic. They do this by melting thin filaments (long strings) of plastic through a heated nozzle in a process called thermo-plastic extrusion. The 3D printer manufactures a 3D object by building it one layer at a time.

3D Printers are actually robots, and most RepRaps are a form of "cartesian robot" which has three (3) perpindicular axes of movement - i.e. X, Y, Z - forward/backward, right/left, up/down. The MendelMax 1.5 is a rugged machine, but like any robot it is has many moving parts which are fragile and wear-out due to normal usage. As such it must be treated with care and maintained occassionally.

To print a 3D object with a MendelMax you need two things:

  1. A MendelMax 1.5 3D Printer
  2. A "GCODE" translation of the object to be printed

Getting both of those things involves several steps. This guide outlines the steps involved to obtain #1. We describe the steps needed to obtain #2 in our User's Guide (TBD).

The Terawatt Industries MendelMax 1.5 for LM8UU 3D Printer is based on the original MendelMax 1.5 3D Printer. It's an open-source printer, so all of the design files for its parts are available online and/or upon request. The bill of materials required to build the printer with the associated design files is also available online and/or upon request.

Things To Know About Building a MendelMax 1.5

The MendelMax can achieve impressive print speed and quality. Nevertheless, printed parts often have tiny flaws evident in the prints. This is normal even on well-calibrated and accurate MendelMax printers. Keep this in mind as you begin your build.

Time

The MendelMax 1.5 typically takes approximately 30 hours +/- 5 hours to complete including extruder; wiring; hotend; locating, compiling, and uploading firmware (Terawatt Industries does this for you) - everything except calibration prints. An experienced builder can complete the gantry within a day, but first-time builders should expect approximately 20-25 hours to complete the gantry. Budget your time for this - if you only work on it during weekends it can easily take 2-3 weeks to complete.

Organization

The most important factor to reduce build time, frustration, and be successful when building a MendelMax is to maintain a high degree of organization. Also we've learned some helpful tips along the way - some might seem obvious but reminders are good:

De-Burring

When assembling printed parts it helps to "de-burr" the part first. De-burring is a process of removing extraneous filament strands and flaws that might obstruct assembly. Screw holes can usually be de-burred with a hex-wrench by inserting the wrench and twisting until motion is relatively unobstructed.

Sometimes a drill makes things easier. If you don't have the exact 3mm, 5mm, or 8mm drill bit you can use the S.A.E. equivalent. If you use a drill, be sure to use a low-speed setting and back the drill bit out repeatedly to remove chips. PLA is easily melted by the friction of a drill bit - when this happens it can easily sieze the bit! ABS is more forgiving. If you use a drill bit and it siezes, reverse the drill and use a high speed - allowing the chuck to spin on the bit until it warms up enough to become un-siezed. Doing that puts premature wear on the drill chuck and/or bit and is to be avoided. It can be avoided by going slowly and constantly backing the drill bit out to remove chips.

Captive nut holes are usually easiest to de-burr by pre-tightening with a screw prior to actual assembly, paying attention to the alignment of the nut so it doesn't strip the plastic slot.

For other types of metal-to-plastic contact, where the fit is tight, the trick is to find the right amount of elbow-grease to complete the assembly without breaking the plastic part. If you're having alot of trouble with a printed part in on of our kits then please contact us.

Captive Nuts

The MendelMax uses a "captive nut" design to facilitate the reliance on one toolset for assembly - hex wrenches. Captive nuts are spaces designed to tension plastic pieces together with a screw and nut. Sometimes the space for the captive nut can be obstructed by extraneous filament (flaws) or very tight. In these situations it usually helps to de-burr the space with a hex wrench or small metal object.

The best way to handle captive-nut assembly in almost all situations is to assemble the nut and screw, then tension the screw to seat the nut in its space. Then unscrew the nut and finish assembly - experiencing frustration with tight-fitting parts is less likely this way.

Clamping Components

The MendelMax and other RepRaps often have components that use plastic clamps. These parts can break if over-tensioned. We recommend keeping noise to a minimum while attaching clamping parts - if you hear them start to crack that's plenty of tension! If something doesn't seem right, don't tension the clamps more; take a break and consider consulting with somebody instead.

Miscellaneous

If you're tightening a screw on a printed (plastic) part and you hear it crack, that's enough tension.

We recommend waiting until the final step of the assembly to tighten all the screws on the gantry (extruder excluded). This guide illustrates this. It's always easier to leave screws at a loose tension during the assembly in case you forget something and have to backup in the assembly. Expect this possibility and plan for it by waiting until the end to tighten everything down, and use that step as a QC step.

Bill of Materials

Though it's not an official reference the Bill of Materials (BOM) for the MendelMax 1.5 for LM8UU is listed at http://store.terawattindustries.com/51-mendelmax-15-complete-printer-kit-in-custom-colors.html. This guide assumes you have the entire BOM already available for your assembly. This guide is intended to be an assembly guide for Terawatt Industries' MendelMax 1.5 for LM8UU 3D Printer. It's not intended to be used as a bill of materials.

Printed Parts

The STLs and SCADs used to manufacture the printed parts for this machine can be downlaoded from http://terawatt-industries.github.com/mendelmax15-lm8uu/.

  1. Bottom-Lower Left Vertex - Qty. 2

  2. Bottom-Lower Right Vertex - Qty. 2

  3. Top-Lower Left Vertex - Qty. 2

  4. Top-Lower Right Vertex - Qty. 2

  5. Top Vertex - Qty. 4

  6. Y-Axis Rod Support - Qty. 2

  7. Y-Idler - Qty. 1

  8. Y-Idler Mount - Qty. 1

  9. Y-Axis Motor Mount - Qty. 1

  10. X-Ends for Precision Leadscrew - Idler

  11. X-Ends for Precision Leadscrew - Motor Mount

  12. X-Carriage - Qty. 1

  13. Hinged Accessible Extruder - Qty. 1

  14. Large Herringbone Gear - Qty. 1

  15. Small Herringbone Gear - Qty. 1

  16. Z-Axis Top Vertex - Qty. 2

  17. Z-Axis Motor Mount - Qty. 2

  18. Z-Axis Motor Mount Support - Qty. 2

  19. Z-Axis Motor Mount Support Mirrored - Qty. 2

  20. Y-Axis Rod Support Clamp - Qty. 4

  21. Z-Axis Top Vertex and Motor Mount Clamp - Qty. 4

  22. Belt Spacer + Tensioners for Universal Y-Axis Plate - Qty. 1
    Note: this is only included with Terawatt's printed parts set if you purchase a universal y-axis plate. otherwise you should have ~10mm tall tensioners.

  23. Endstop Mounts for Mechanical Endstop Switches - Qty. 3

  24. Spool Filament Holder Mount - Qty. 2

  25. 70mm Jig for Top Extrusion - Qty. 1
    Note: optional part. This is not included in Terawatt Industries' complete kit or gantry kit since Terawatt only sells pre-drilled extrusion.

Tools Needed

The MendelMax is designed so that your primary tool is a set of hex wrenches for more than 90% of the assembly. In fact the entire gantry only requires hex wrenches and a T-25 screwdriver. Aside from the gantry a couple of other components require tools that are typically easy to acquire; you either have them already or can get one from a local hardware store. To build a complete Terawatt Industries MendelMax you need the following tools:

Assembling The Gantry

Top Vertex

Where We're Going

We're going to build this:

BOM

  1. 2pcs 420mm-length t-slot aluminum extrusion, pre-drilled @ 70mm from ends; pre-tapped.
  2. 4pcs 340mm-length t-slot aluminum extrusion, tapped on one-side
  3. Rather than list the screws, washers, etc. that we need for each step - we're going to rely on an organizer tray for our BOM. Terawatt Industries provides an adjustable organizer tray to hold your hardware. You can also use resealable plastic container from the grocery store - but be warned - hardware is dirty and comes from unknown sources so once you use a container for hardware consider it permanently unusable for food!

    We don't recommend leaving the hardware in bags because they will spill at the wrong time and place. Fill your organizer tray(s) with:
    • M5 T-Slot nuts, for aluminum extrusion
    • 4pcs M5 Self-Threading screws
    • M5x12mm screws
    • M5x10mm screw
    • M5 lock washers
    • M5 fender washers
    • M5 std. washers
  4. 2 pcs. Z-Axis Top Vertices - pre-loaded with M5x12mm screws, lock washers, and std. washers.

Session 1 - Top Vertex

First we'll assemble the top vertex

Step 1.1: Frontside Top Vertex

  1. Slide one self-tapping screw into the extrusion the 420mm-length extrusion from the side. Line it up roughly with the drilled hole at 70mm.
  2. Attach the untapped side of one 340mm-length extrusion to the M5 self-tapping screw with a T25 screwdriver.
  3. Repeat for the other 70mm hole.

Step 1.2: Backside Top Vertex

Repeat the steps above for the backside top vertex (they look the same right now).

Step 1.3: Top Vertex Part 1

  1. You'll need enough space for two vertices on your bench.
  2. Pay attention to the orientation of the top vertex printed part - it attaches to the extrusion at an angle.
  3. Did you pre-load the z-axis top-vertices with M5 hardware?
  4. Attach a printed top-vertex part to one vertex.
  5. Attach the other vertex to the printed part to form one side of the top-vertex assembly. Again pay attention to the angle. Deburring corners on the top-vertex part can usually be performed with sandpaper if necessary.
  6. Tighten the screws a half-turn to prevent them from falling out easily - but don't tighten all the way. We always recommend leaving everything loose - but not loose enough for screws to fall out - until the very end.

Step 1.3: Top Vertex Part 2

Let's complete the top vertex.

  1. Slot t-slot nuts as illustrated into each side of the top vertex, at the very top. These are for the spool filament holder and the other top vertex.
  2. Attach the other printed top vertex part, paying attention to de-burring.
  3. Again tighten the screws a half-turn - loose but not too loose.

Session 2 - Top Vertex - Lower Part

Step 1.4: Prepare for Lower Vertex - Front

We're going a couple steps further to prep for the lower vertex; and in the end we'll just attach upper and lower to form the skeleton of the gantry.

  1. Flip the top vertex over, upside-down.
  2. Pick a side, any side. Insert three (4) t-slot nuts on the front of the left-arm (extrusion).
  3. Insert three (3) t-slot nuts on the outside face of the left arm (extrusion, facing outward).
  4. Insert three (3) t-slot nuts on the front of the right-arm (extrusion).
  5. Insert three (3) t-slot nuts on the outside face of the right arm (extrusion, opposite to above step).
  6. Attach two (2) Top-Lower Vertices to both arms using M5 screws without washers.
    • NOTE: The 340mm extrusion is tapped on one side. If you installed the top vertex incorrectly that's OK just breakout the T25 screwdriver and flip it.

Step 1.6: Prepare for Lower Vertex - Rear

We established the "front" of the machine with differing numbers of t-slot nuts. Now let's build the rear.

  1. Flip the top vertex over, upside-down.
  2. Insert three (4) t-slot nuts on the outside face of the left arm (extrusion, facing outward).
  3. Insert three (3) t-slot nuts on the outside face of the left arm (extrusion, facing outward).
  4. Insert three (4) t-slot nuts on the front of the right-arm (extrusion).
  5. Insert three (3) t-slot nuts on the outside face of the right arm (extrusion, opposite to above step).
  6. Attach two (2) Upper Lower-Vertices as in Step 1.5.
  7. Admire your work!

Session 3 - Top Vertex

Step 1.7: Top Vertex Advance Prep

Let's de-burr and pre-load the captive nut holes on the top vertices before proceeding. Sometimes this can be difficult and it's easier to handle when the top vertex is partially assembled. You'll need 4pcs. M5 Thin Nuts supplied with your kit. The captive nut holes are for M5 Thin Nuts and can be deburred with a hex wrench. It may take some work to de-burr and get the nuts to line up or move freely. If the nut is tight and difficult to align it sometimes helps to pull it from the side, being careful not to strip threads. Note the hole on the bottom of the top vertex (printed part) - it's for a hex-wrench to hold a nut that's spinning freely in its slot, in case this happens.If you need to turn the vertex around or flip it over, be careful not to break any protruding parts from the Upper Lower-Vertices in previous steps.

Assembling The Gantry

Bottom Vertex

Where We're Going

We're going to build this:

BOM

  1. 2pcs 300mm-length t-slot aluminum extrusion; pre-tapped.
  2. 4pcs 420mm-length t-slot aluminum extrusion; not tapped.
  3. M5 T-Slot nuts, for aluminum extrusion
  4. M5x12mm screw
  5. M5x10mm screw
  6. M5 lock washer
  7. M5 fender washer
  8. M5 std. washer

Session 4 - De-burr and Pre-Assemble

First we'll clean the parts for the lower vertex and prepare them for assembly. IMPORTANT: when "pre-loading" t-slot nuts they should only be threaded 2-3 threads, at most. If threaded more then they won't fit into the sides of the extrusion.

Step 2.1: De-burr and Pre-Assemble

  1. De-burr the screw holes and captive nut slots on the following printed parts: z-axis motor mounts, z-axis motor mount supports, y-rod supports, y-axis motor mount, and y-axis idler mount and idler.

Step 2.2: Pre-Assemble Y-Rod Supports

  1. Pre-load M5 t-slot nuts on the y-axis rod supports using M5x12mm screws, lock washers, and std. washers.
  2. Attach the y-rod support clamps using M5x20mm screws, lock washers, std. washers, and M5 standard nuts. Tighten the screws until the nut is held properly in its slot - then loosen the screw so the smooth rod can be inserted into the clamp in a following step.

Step 2.2: Pre-Assemble Y-Axis Motor Mount

  1. Pre-load M5 t-slot nuts on the y-axis motor mount using M5x12mm screws - washers are optional here, lock washers are not recommended.

Step 2.3: Pre-Assemble Y-Axis Idler

  1. Insert captive nuts into the y-axis idler as pictured. If there are obstructions in the captive nut slot clear them with a hex wrench and/or safety-handle razor blade.
  2. Attach the y-idler to the y-idler mount using two (2) M5x12mm screws, lock washers, and std. washers.
  3. Pre-load the y-idler mount with T-slot nuts using M5x12mm screws, lock washers, and std. washers.

Step 2.4: Pre-Assemble Z-Motor Mounts

  1. Insert four (4) captive nuts into the z-motor mount. If there are obstructions in the captive nut slot clear them with a hex wrench and/or safety-handle razor blade.
  2. Attach a NEMA 17 motor to the motor mount with M3 screws, lock washers, and fender washers.
    • Pay attention to the fit of the motor in the z-axis support.
    • NOTE: you may have to cope with extraneous plastic adjacent to the motor - it's for the captive nut slots on the end of the mount which hold the clamps. If this is the case the plastic can be warmed with a lighter and molded with the side of a motor. It can also be cut with snippers. Be careful to leave some plastic to hold the nut.
    • The goal is to allow the motor some room for adjustment (it has slots for this) and provide a flat surface so it's flush when mounted. The problem is: in the MendelMax 1.5 design (STL) this lengthy bridge only receives 2-3 layers of material.
  3. Attach the z-axis motor mount supports to sides of the mount using two (2) M5x10mm screws, lock washers, and std. washers.
    1. Orientation of the motor mount supports can seem confusing at first; just build one support at a time based on the photos.
  4. Pre-load four (4) M5 t-slot nuts onto the z-axis motor mount and support arms using M5x12mm screws, lock washers, and std. washers.
  5. Attach a NEMA 17 motor to the z-axis motor mount using four (4) M3x10mm screws, lock washers, and fender washers.
    1. Pay attention to wire orientation - usually facing towards the gantry or to the side works well.
  6. Repeat the steps above for the second z-axis motor mount.

Session 5 - Pre-Assemble Lower Vertex

Step 2.5: Pre-Assembly Quality Check

  1. Double-check that the printed parts are pre-assembled and pre-loaded with t-slot nuts.

Step 2.6: Pre-Assemble Sides of Lower Vertex

  1. Slide one 420mm length aluminum extrusion into the t-slot nuts of the z-axis motor mount. Repeat with a second piece of 420mm length extrusion to form a side of the lower vertex.
  2. Repeat the above step with the other two (2) pieces of 420mm extrusion and z-axis motor mount.
  3. Attach one printed bottom-lower vertex to the side you just assembled. The smooth side (face) of the lower vertex should face outward, like the motor mount. Note that left and right side of the frame are symmetric, except for RAMPS and PCB mounting options. We recommend installing RAMPS on the right side and thus some additional PCB mounts or wiring guides on the right side.
    1. Slide the pre-loaded t-slot nuts into the extrusion from the side about halfway, leaving enough room for a piece of extrusion to fit at a right angle (see picture).
  4. Pre-load two (2) t-slot nuts on "top" of this dual-rail assembly - we'll need these to attach the upper vertex.
  5. Pre-load additional t-slot nuts (optional) for RAMPS and PCB-connector mounts. There are also options to install these mounts post-assembly with the Terawatt Industries 20mm Extrusion Clip.
  6. Repeat step 3.4.2 above to attach the other printed bottom-lower vertex. This is a good time to double-check that all t-slot nuts are present to attach the upper vertex and any parts for later steps.
  7. Repeat the steps above for the other side of the lower vertex. Pay attention to the photos for optional t-slot nuts for RAMPS and PCB connector mounting. We recommend installing RAMPS on the right side and thus some additional PCB mounts or wiring guides on the right side.
  8. Triple-check that there are t-slot nuts to attach the upper vertex and any required/optional components.

Step 2.7: Pre-Assemble Front and Rear of Lower Vertex

  1. Slide one 340mm length aluminum extrusion tapped for M5 screws into the t-slot nut of the y-axis rod support.
  2. Repeat with a second piece of 340mm length aluminum extrusion tapped for M5 screws. This forms the front of the lower vertex.
  3. Slide the y-axis motor mount into this dual-rail assembly on the opposite side of the rod-support you just installed.
  4. Pre-load two (2) t-slot nuts on "top" of this dual-rail assembly - we'll need these to attach the upper vertex.
  5. The "front" is the component with the y-axis motor mount.
    • (Optional) Slide one (1) t-slot nut into the top rail, facing outwards (see previous photo) - these are for attaching an ATX/PC power supply adapter board and/or PCB Connector mounts.
    • (Optional) Slide two (2) t-slot nuts into the bottom rail - these are for attaching a power-supply (PSU) mount.
  6. The "rear" is the component with the y-axis idler.

Session 6 - Assemble Lower Vertex

Step 2.8: Assemble Lower Vertex

  1. First: do you have all the t-slot nuts on the dual-rail assemblies that you'll need to attach the upper vertex? What about optional t-slot nuts like the PSU mount, RAMPS, other options mentioned previously - or maybe a new attachment or design you plan to experiment with?
  2. Locate the lower-right-side of the frame - the one you just assembled with z-axis motor mount and extra t-slot nuts for RAMPS (optional).
  3. Locate the lower-front-side of the frame. This has the y-axis motor mount.
  4. Note the 340mm length extrusion is tapped on both sides for M5 screws.
  5. Place the lower-front-side of the frame at a right angle to the lower-right-side. The printed lower-vertex should only be partially inserted to accomodate it.
  6. Screw two (2) M5x12mm screws into the side of the printed part - into the M5 tapped holes in the 340mm length extrusion.
  7. Locate the lower-rear-side of the frame. This has the y-axis idler.
  8. Repeat the above steps to attach the rear to the right side of the frame.
  9. This is a good time to make sure there are t-slot nuts on the front of the extrusion for the remaining M5 screw holes on the printed lower vertex. For both front and rear: there should be two (2) t-slot nuts on each rail for a total of four (4).
  10. Attach the left side of the frame using M5 screws, lock washers, and fender washers.

Assembling The Gantry

Assemble the Universal Y-Axis Plate

Where We're Going

We're going to build this:

BOM

  1. Universal Y-Axis Plate
  2. Printed PLA Spacers with LM8UU Mounts
  3. Printed ABS Belt Tensioners for GT2 Belt
  4. 4pcs. LM8UU linear bearings for 8mm smooth rod
  5. 1180mm or longer GT2 belt
  6. 12pcs. M3x45mm screws
  7. M3x25mm screw
  8. M3 lock washer
  9. M3 fender washer
  10. M3 std. washer

Session 7 - Assemble Y-Axis Plate

Step 3.1: Attach Spacers

  1. De-burr the spacers and LM8UU mounts. De-burring the screw holes helps alot, otherwise you'll need to thread the entire M3x45mm screw through the spacer. If you use a drill to de-burr the screw holes be sure to read our advice on de-burring with a drill at the beginning of this guide.
  2. Pre-load four (4) LM8UU linear bearings into the printed LM8UU mounts.
  3. Slot two (2) M3x45mm screws through the y-axis plate to mount the spacer. Due to tight alignment tolerances it helps to mount the spacer onto both screws at once rather than one screw at a time.
  4. Attach a PLA spacer to the screws. You may still need to thread the M3x45mm screws through the spacer after de-burring.
  5. Repeat the above steps for the remaining (3) spacers.

Step 3.1: Attach LM8UU Mounts

  1. Attach one (1) LM8UU mount to each spacer with two (2) M3 nuts. Tighten it so it's ready for printing.
  2. Repeat for the rest of the LM8UU mounts.
  3. Finish assembling the LM8UU mounts.
    1. Insert one (1) M3x25mm screw and one (1) M3 nut into the sides of the LM8UU mount. Each mount has an opening for a socket cap screw (M3) and a captive slot for an M3 nut. Do not use washers - they don't fit on this design (currently).
    2. Tighten the screw to hold the LM8UU bearing. Don't overtighten. If you hear a crack or see signs of stress in the plastic - that's enough tension.
  4. Repeat for the rest of the LM8UU mounts to tension each LM8UU bearing in its mount.

Session 8 - Attach Y-Axis Plate to Gantry

Step 3.2: Assemble Belt Tensioner

  1. WARNING: there's significant room for frustration here. Take your time. If you have to skip using standard and/or lock washers to get things to fit, then do it.
  2. Note the tensioner parts have smooth sides and grooves on the other side. The grooves are to help grip GT2 belts. The smooth side will hold a belt with proper tension just as well.
  3. Insert two (2) M3x45mm screws with M3 fender washers (no lock washers) into the top of the plate for a belt tensioner. As with the PLA spacers these are easiest to install with both screws at once.
  4. On the bottom side of the plate stack a tall tensioner onto the screws. Then stack a short one on top. Note the GT2 grooves on the printed parts.
  5. Tighten the tensioner using an M3 washer, M3 lock washer, and M3 nut. To get things to fit (currently) you may need to skip some washers.
  6. Do not fully tighten the belt tensioner stack. We still need to slot a belt into it, then we'll tighten.
  7. Repeat for the second tensioner.
  8. NOTE: these tensioners do not have built-in adjustments -- on the MendelMax this is handled by the y-axis idler mount.

Session 9 - Attach Y-Axis Plate to Gantry

Step 3.3: Attach Y-Axis Plate to Gantry

  1. Insert two (2) 495mm length smooth rods through a y-rod support clamp. Don't insert the rods all the way through to the other clamp - we need to install the y-axis plate first.
  2. Carefully attach one side of the y-axis plate assembly to the smooth rod within the gantry. Slide the smooth rod through each LM8UU, one at a time. It's especially important to go slowly, be gentle, and insert the bearing straight onto the rod.
    • If you're not careful, insert at an angle, or need to use too much force it's likely to lose some ball-bearings from the LM8UU; which reduces the lifetime expectancy of the bearing, sounds noisy, and can introduce tiny artifacts into printed parts.
  3. Slide the other smooth rod through each LM8UU, one at a time, again being very careful not to lose LM8UU ball-bearings.

Step 3.4: Assemble Y-Axis Idler

  1. Assemble the y-axis idler using one (1) M8x40mm screw, two (2) 608 bearings, and washers.
    1. Insert the M8x40mm screw into the idler partially.
    2. Add 608 bearings and washers before threading the M8x40mm screw through the idler completely. Use M8 standard washers on the outside of 608 bearings - an M8 Fender Washer will rub against the spinning part of the 608 bearing so it always needs a spacer.
    3. Tighten the M8x40mm screw with an M8 nut.
  2. Assemble the tensioner adjustment screw using one (1) M5x30mm screw, two (2) M5 nuts, and one (1) M5 fender washer.
    1. Pre-load one (1) M5 nut and M5 fender washer onto the M5x30mm screw.
    2. Thread the M3x30mm screw with nut+washer into the idler 'top' -- note the idler has a hole with a captive nut for this.
    3. Thread the other M5 nut onto the M5x30mm screw and tighten into the captive nut space.

Step 3.4: Attach Y-Axis Motor

  1. Attach the y-axis motor using two (2) M3x12mm screws, lock washers, and fender washers.
  2. Attach a GT2 pulley to the Y-Axis motor and tighten the set screw.

Session 10: Finish Y-Axis

Step 3.4: Attach Y-Axis GT2 Belt

  1. Turn the lower vertex assembly with attached y-axis plate upside-down.
  2. Locate a 1180mm (or longer) GT2 belt. If it's a closed-loop belt then cut it with sharp scissors.
  3. Insert the GT2 belt face up into the tensioner closest to the y-axis motor, leaving 1-2" to dangle from the end of the tensioner. Tighten the tensioner onto the belt.
  4. Thread the belt around the GT2 pulley on the y-axis motor. The belt should run "under" the belt tensioners -- or now that we're looking upside-down at the bottom, over the tensioners.
  5. Close the loop by threading the belt over the tensioner on the other side of the gantry.
  6. Position the GT2 belt on the other tensioner and tighten as you did with the first tensioner (above).

Step 3.4: Quality Check Y-Axis and Lower Vertex

  1. Admire your work!
  2. Most of these parts should still be loose -- but not so loose that screws fall out of t-slot nuts.
  3. Double and triple-check to make sure you have the t-slot nuts you'll need for the top vertex and mounting options such as RAMPS or PSU mount.
  4. Double check that the z-axis motor mounts have captive nuts for their clamps.

Assembling The Gantry

Finish the Gantry

Where We're Going

We're going to build this:

BOM

  1. Assembled Gantry Upper Vertex
  2. Assembled Gantry Lower Vertex
  3. (8) M5 screws with lock washers and standard washers.

Session 11: Attach Vertices

Step 4.1: Attach Upper and Lower Vertices

  1. If you've gone through this guide and built everything to this point, you can probably look at the picture and see what needs to happen.
  2. You should have pre-loaded t-slot nuts on the lower gantry to complete this step.
  3. Place the assembled upper gantry on top of the lower gantry.
  4. Use eight (2) M5 screws with standard washers to attach one lower vertex to the lower gantry.
  5. Repeat for the other (3) vertices to completely attach upper and lower vertices of the printer.

Assembling the MendelMax 1.5 for LM8UU

Assembling X-Ends and X-Carriage

Where We're Going

We're going to build this:

BOM

  1. Set of printed X-Ends: motor mount and idler. Terawatt prints these in PLA for stiffness but that adds a twist to de-burring this complex part.
  2. Two (2) precision leadscrew nuts. The x-ends that come with the Terawatt Industries printed parts are designed for this leadscrew nut and matching leadscrew.
  3. Printed x-carriage with (3) belt tensioner parts. Terawatt prints this in ABS.
  4. 2pcs. Linear Smooth Rod, 8mm diameter, 495mm length (406mm length works too).
  5. LM8UU bearings
  6. M3 screws: 16mm, 20mm, 25mm lengths; M3 lock washers, M3 std. washers, M3 fender washers, M3 nuts
  7. M8x40mm screw, 608 bearings, M8 std. washers and fender washer for x-end idler.

Session 12: X-Axis #1

Step 5.1: Pre-Assemble X-Ends

  1. Locate an x-end, any x-end. Insert two (2) LM8UU linear bearings into the bearing holder.
  2. Tighten the bearings in the holder with two (2) M3x25mm screws and two (2) M3 nuts. Washers will not fit in this part. Tighten these screws completely.
  3. Insert a precision leadscrew nut into the x-end.
  4. Tighten the leadscrew nut with three (3) M3x20mm screws, three (3) M3 fender washers, and three (3) M3 nuts. Tighten these screws completely.
  5. Insert two M3x16mm (or 20mm+) screws, M3 lock washers, and M3 fender washers into the x-ends clamping holes - located between the leadscrew nut and bearing holder.
  6. Tighten the M3x16mm screws in the above step with M3 nuts, and de-burr the captive nuts by completely tightening. Then loosen so we can insert smooth rods into the x-ends later.
  7. Repeat the above steps for the other x-end.

Step 5.2: Attach Idler (1) X-End To Smooth Rods

  1. De-burr the 8mm holes in the x-ends. This can be challenging - an 8mm drill bit can be very handy but this can be done by hand with a hex wrench.
  2. Locate the x-end for the idler mount.
  3. Insert one (1) of the 8mm smooth rods, 495mm length, into the x-end for the idler mount. Insert it all the way into the x-end. Expect to use some force but not enough to break the part. If you have to use too much force try de-burring a little more - eventually you will get it. If it's not going to work then contact your printed parts supplier for support.
  4. Insert the other 8mm smooth rod, 495mm length into the x-end for the idler mount.
  5. On this x-end there is a z-stop obstruction that limits how far the smooth rod can be inserted. Line both smooth rods up to this.
  6. De-burr the M2.5 hole on the z-stop with a hex wrench.

Step 5.2: Finish Assembling X-End Idler

  1. You'll need one M8x40mm screw (35mm will work), two (2) 608 bearings, two (2) M8 fender washers, and at least two (2) M8 std. washers.
  2. Stack an M8 fender washer and std washer on the screw.
  3. Stack the 608 bearings and std. washer.
  4. Finally place a fender washer to complete the stack.
  5. Insert the idler stack into the printed x-end idler mount, thread an M8 washer and nut, and tighten.

Session 12: X-Axis #2

Step 5.3: Attach X-Carriage Bearings

  1. Set the partially assembled x-ends and smooth rods aside.
  2. De-burr the x-carriage screw holes - you can de-burr the captive nuts during assembly.
  3. Insert four (4) LM8UU linear bearings into the x-carriage bearing holders.
  4. Insert one (1) M3x25mm screw without washers into the bearing holder screw hole. Insert an M3 nut into the corresponding captive nut slot.
  5. Tighten the M3 screw until you see the plastic stress or hear it crack.
  6. Check with your hand that the bearing is secure.
  7. Repeat for the other 3 bearing holders.

Step 5.4: Assemble X-Carriage Belt Tensioners

  1. Note that while this design allows for belt-tension adjustment with an M3 screw, we've found the M3 screw reliably tears GT2 belts so we don't use it and simplify the assembly as a result.
  2. Again note these tensioners have grooves for GT2 belts.
  3. Pre-load two (2) M3x30mm screws with std. washers.
  4. Attach the screws to one of the x-carriage belt tensioners.
  5. Flip the x-carriage upside-down and attach a second belt tensioner part.
  6. Add an M3 std. washer, M3 lock washer, and M3 nut, then tighten - leave it loose to insert a GT2 belt however.
  7. Optional: if you have a wire-clip you can attach it to the top of one of the M3x25mm or M3x30mm screws before assembling the tensioner(s).
  8. Attach the third (3rd) tensioner part to the x-carriage with two (2) M3x25mm screws, with standard washers on top. And washers, lock washers, and nuts on the bottom like the previous tensioners.

Step 5.5: Attach X-Carriage To Smooth Rods

  1. Locate the pre-assembled x-end with attached 8mm smooth rods from the previous step(s).
  2. Locate the x-carriage and carefully slide it onto the 8mm smooth rods. The belt tensioners should be on the same side as the idler (and motor). Go slowly and be gentle. As with the y-axis, if you use to much force or insert the carriage at an angle you're likely to hear tiny ball bearings fall out of the LM8UU case (which means the life expectancy is of the bearing is reduced as well as overall print quality).
  3. IMPORTANT: observe x-carriage orientation so that the belt tensioners are on the same side as the idler and motor.

Step 5.6: Attach Other X-End To Smooth Rods

  1. Make sure you have the proper orientation for the x-carriage. The belt tensioners should be on the same side as the idler and motor.
  2. Locate the pre-assembled x-end with attached 8mm smooth rods and x-carriage from the previous step.
  3. Locate the x-end for the motor mount.
  4. Insert one (1) of the 8mm smooth rods, 495mm length, into the x-end for the motor mount. Insert it all the way into the x-end, but not through. Expect to use some force but not enough to break the part. If you need to de-burr the 8mm holes in the printed part do that rather than use excessive force.
  5. Insert the other 8mm smooth rod, 495mm length into the x-end for the motor mount.
  6. Set the partially assembled x-ends and smooth rods aside.

Session 13: X-Axis #3

Step 5.7: Attach GT2 Belt for X-Axis

  1. NOTE: do not install the precision leadscrews yet - ignore them in these photos.
  2. Locate the pre-assembled x-axis and an 1180mm length GT2 open-loop belt. If you have a closed-loop belt then cut it open.
  3. Loop the belt around the x-end for the motor mount.
  4. Pull the belt around to the idler. Don't allow the belt to twist along the loop.
  5. Loosen the (both) x-carriage belt tensioner and insert the belt. Then slot it through the adjacent opening with a hex wrench.
  6. Insert the belt through the bottom tensioner and tighten the M3 screws.
  7. Take the other end of the GT2 belt loop and insert through the belt tensioner, into the adjacent slot as before.
  8. This is a good time to make sure the belt has enough overlap on at least one side to be re-tightened during maintenance at another time.
  9. Tighten the M3 screws + nuts on one (1) tensioner on the x-carriage.
  10. User your hand to tension the belt. Alternatively wrap the belt around something that provides leverage like needle-nose pliers. Don't over-tension - the belts can become damages and frayed from too much tension.
  11. Tighten the M3 nuts on the second tensioner as you apply tension to the GT2 belt.
  12. Expect to have to make alignment adjustments in following steps, so don't worry too much about getting tension perfect here.
  13. Check the tension on the belt. The goal here is to have a belt that isn't too loose - i.e. flopping around on the GT2 pulley. The goal is not to make the belt as tight as possible. If it's too loose, re-tension. If tensioning by hand doesn't work then use a lever but don't use much force.
  14. Re-check everything, tuck excess GT2 belt away securely, and cut any excess you can't tuck away. Try to leave some for maintenance another day.
  15. Expect to make adjustments in following steps and/or during calibration.

Assembling the MendelMax 1.5 for LM8UU

X-Axis Mates with Gantry

Where We're Going

We're going to build this:

Session 13: X-Axis #3

Step 5.7: Attach GT2 Belt for X-Axis

BOM

  1. Pre-assembled MendelMax 1.5 for LM8UU Gantry.
  2. Two (2) precision leadscrews.
  3. Two (2) z-axis 5mm-to-8mm flexible aluminum couplers.
  4. Two (2) 8mm linear smooth rod, 406mm length.
  5. Pre-assembled MendelMax 1.5 X-Axis with X-ends for precision leadscrew with matching nuts (the x-ends in this guide).
  6. Optional: Tefla clip with M4 hardware for wire-strain relief on heatbed; or use another clip for strain relief. any strain relief is better than no strain relief; and non-flammable components are even better here.

Session 14: Z-Axis Smooth Rods

Step 6.1: Install Z-Axis Motor Couplers

  1. Locate one (1) 5mm-to-8mm z-axis aluminum coupler.
  2. Install the coupler with 5mm bore to a z-axis motor.
  3. Line the 5mm motor shaft up to the 8mm bore in the coupler.
  4. Tighten the coupler set screw.
  5. Repeat for the other (second) coupler and z-axis motor.
  6. Make sure the set screws are tightened - but don't over tighten.

Step 6.2: Place the X-Axis

  1. Slide the pre-assembled x-axis with GT2 belt into the gantry from the side.
  2. Line up the precision leadscrew nuts with the flexible z-axis couplers.
  3. Expect to make alignment adjustments now and/or later during calibration.
  4. Don't expect perfect alignment. Closer is better, closest is best.
  5. Check alignment:
    • Looking down from above you should be able to see through the leadscrew nut into the z-axis coupler - hopefully right through the middle of the coupler.
    • Common alignment issues here are caused by x-ends and that either too far apart, or too close together. To make adjustments to x-ends positioning be sure to loosen the GT2 belt, then re-tension once alignment adjustments are complete.
    • Another common alignment issue is a mis-aligned z-axis motor coupling. Just make sure the motor shaft is straight and seated to the 8mm bore. If it just doesn't seem proper make sure the bore-sizes on the coupler are 5mm and 8mm as expected.
    • Don't expect a z-axis constraint to correct alignment issues. It may help but it's better to improve alignment at this stage.
    • Take a break or ask for help if it becomes a problem.

Step 6.2: Install 8mm Z-Axis Smooth Rods

  1. Locate one (1) 8mm diameter, 406mm length linear smooth rod.
  2. Slide the linear smooth rod through the x-end's LM8UU bearings from the top. As always, be gentle and don't go at an angle; otherwise expect to lose tiny ball bearings! Slide the rod through both LM8UU's, one at a time. Being gentle can be more challenging than before depending on alignment.
  3. Slide the linear smooth rod into the groove at the bottom.
  4. Align the bottom linear smooth rod with the bottom of the motor.
  5. Assemble a z-axis clamp with two (2) M5x12mm screws. The motor mount and top-vertex clamps are the same.
  6. Tighten the top z-axis clamp with M5x12mm screws. Leave it a little loose to make it easier to attach the bottom clamp.
  7. Tighten the bottom z-axis clamp with M5x12mm screws. If it won't thread try loosening things until you get a thread started, then re-tighten.
  8. Repeat the above steps for the other 8mm smooth rod.

Session 15: Make It Happen

Step 6.2: Install 8mm Precision Leadscrew

  1. Thread a precision leadscrew into an x-end from the top.
  2. Thread the leadscrew through the matching nut in the x-end.
  3. Lift the x-axis 50-100mm (2-4") with your hand and thread the leadscrew further; into the flexible z-axis coupler.
    • If alignment is good you will be able to thread the leadscrew into the coupler and touch the 5mm motor shaft.
    • The couplers are flexible to allow some alignment tolerance. Don't expect perfect alignment: closer is better, closest is best.
  4. Repeat the above steps for the second (2nd) leadscrew.
  5. Tighten both z-axis flexible coupler set screws onto the precision leadscrews. Otherwise, the motor will spin and you'll wonder why the z-axis doesn't work.

Assembling the MendelMax 1.5 for LM8UU

Top Vertices

Where We're Going

We're going to build this:

BOM

  1. Nearly fully-assembled MendelMax 1.5 for LM8UU built from steps above.
  2. Four (4) printed top-vertex parts.
  3. M5x10mm screws, M5 fender washers, M5 lock washers.

Session 16: Finish It Up!

Step 7.1: Install Top Vertices

  1. You're no longer a novice at building a MendelMax! We're not going to hold your hand through this part - you're almost there. The catch is: did you remember all the t-slot nuts? If not there's a simple way to get them in post-assembly (placeholder please ask to fulfill).
  2. Use M5x10mm screws and M5 fender washers with lock washers for the top vertices.
  3. It's easier to attach the vertices from the side.
  4. It helps to use a second hex-wrench to hold t-slot nuts up while attaching the top vertex.
  5. Repeat the above steps to attach the remaining three (3) top vertex parts.

Step 7.2: QC and Tighten Everything

  1. Go through the entire gantry and tighten everything. Don't break any plastic! Remember, if you hear it crack or see stress marks then it's tight enough.

Step 7.3: Congratulations

  1. You've built the frame! Toast to your accomplishment. Next is extruder, hotend, and wiring - then calibrate and print.