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QuorXZ: A String-driven, Core XZ Printer

Discussion in '3D printers' started by Scotty Orr, Aug 30, 2017.

  1. Scotty Orr

    Scotty Orr Journeyman

    May 21, 2015
    Likes Received:
    Scotty Orr published a new build:

    Read more about this build...
  2. Scotty Orr

    Scotty Orr Journeyman

    May 21, 2015
    Likes Received:
    Thank you for reading the build of the QuorXZ. This space is reserved for additional notes about the build.

    Due to problems I am having with the Captchas and the Build Editor, I am continuing the build documentation here. If I can overcome the problems, I will move this information to the Build properly. Build continued below....

    7c: Install the Extruder and its Stepper
    • Install the Titan extruder. If you are using the Titan Extruder, you will not be able to use the stepper mounting screws included in the kit. (You will use the 1 shorter corner screw holding the outer case on.) The screws included with the kit allow you to install to a plate thickness of up to 7mm. The case of the QuorXZ is 10mm so their longest screws (3 35mm and 1 12mm) are too short. Substitute 3 M3x40mm and 1 M3x16mm to mount into the actual stepper. Even though the shaft does not go into the hobbed gear quite as far as they expect, the Titan is working extremely well on my machine. Follow the instruction included with the Titan to complete the assembly and installation.
    • Install the printed extruder. Grab the MK8 hobbed gear from it's storage in the extruder assembly and attach it to the stepper with about 3mm of the shaft exposed (tighten the set-screw on the flat only enough to keep it from rotating).
    • Hold the stepper in the hole from the inside of the case, with the gear set-screw facing the front of the printer. With your second hand, grab the extruder assembly (with the 4 screws sticking out), and place it on the outside of the case, feeding the shaft/with gear into the opening, and with the lever facing the front of the printer, and feeding the screws into the hole. With your third hand start at least a couple of opposing screws into the stepper body. Tighten all screws securely.
    • Lift the lever, and with a hex driver in the gear set-screw, align the teeth of the hobbed gear with the bearing in the lever. Tighten the set-screw completely.
    Step 8: Final Assembly and Stringing!
    Finally!! This is where everything comes together. In a few more short hours, you will have your very own singing, moving QuorXZ.

    You will need the following parts for this step.

    8a: Remove Parts
    • Remove the top of the printer case and set aside (but within reach).
    • If you've been storing your printer bed on the rails, remove it.
    • If you installed the large string bearing guides at the top of the Z-rails, remove them.
    • If you installed your hot end to the X-gantry, remove it.
    8b: Install and Adjust the XZ-Gantry Assembly
    This step will require 3 or 4 hands, amazing dexterity and some small wrenches. In particular you will need a thin bicycle wrench to adjust the thin eccentric spacers. You can use some extra string for one of your hands.
    • Grab an extra yard of string, and keep it nearby.
    • Slightly only, loosen the screws attaching the Y-gantry ends to the X-rail (two on the back and one on the front on each end).
    • Working from the back of the printer, lift the XZ-gantry assembly, with the X-gantry plate facing forward (and right side up - X plate with eccentrics on top) and large Y-gantry plates facing backwards, drop the XZ-gantry assembly in place over the Z rails. You may have to wiggle it a bit to for the small front plates to clear the case opening. Don't worry too much about getting all the bearings aligned yet.
    • With one hand, hold the assembly about half-way down the Z-rails. With the other hand, replace the top part of the printer case (no screws needed for now). Grab the string, and wrap it around the X-gantry and X-rail and feed the ends, one through the slot in top cover, and one around the wood next to the slot. Tie a knot in the string to hold the XZ-gantry assembly at about the halfway point of the Z-rails. Now you only need two hands for the remaining parts.
    • Still working from the back, Spread the Z-gantry plates equally to the outside, engaging the bearings closest to you on the inside of the Openrail linear rail. Tighten the screws closest to you, going back and forth between the ends of the assembly to make sure that those bearings on both ends of the assembly are fully engaged. (You also want to keep the assembly as level as possible. If you want to add another string or to help with this, do so.). Once the rear plates are set, make sure the bolts are not racked and tighten the front plates to the X-rail.
    • Next, you'll need an open end wrench to grab the nuts on the back of the outside of the assembly. These were left very loose, so snug them up now, ensuring that the outer bearings closest to you are riding on the rail. Don't worry too much about the eccentric spacers during this step.
    • Now, you will need to make sure the X-rail is perfectly parallel with table surface, or other horizontal plane (can put the print bed in temporarily if that helps). Adjust the eccentrics using the thin wrench. You'll need to swap wrenches for the nut and spacer, and work back and forth from side to side, checking level frequently. You can move the XZ-gantry up and back to its centered position to check. Once you've gotten rid of all of the play, temporarily remove the string, and check the travel on the entire length of the Z-rails (adjust as needed)
    • Install the upper string guide bearings that you had set aside earlier.
    For the next step you should leave the top cover in place (add a few screws) with the gantry suspended half way up. If you find the top getting in the way, find a box or a block of wood to hold the gantry up from below. I did mine with top in place using the suspension method.
    8c: String (and Tension) the XZ Plane
    (A picture is worth a thousand words)

    A note about string tension, doubled bearings, and MDF:
    MDF will compress. Before you begin, you should retighten all screws bearing some metal through the MDF. This includes bearing posts and rail holders for this step, but you should check all of them. If your string is too tight, and your bearing bolts are not tight enough, the string can force itself between the bearings. Recheck the tightness every week or so for the first month of use. I only had an issue once, and it was early in the life of the printer. Don't overdo it, you still want the bearings to turn.
    • Route the string as shown in the image above. Complete both ends of one spool before moving to the other spool. Notice that the strings cross below the Y-rail, so does it matter which spool you work on first? Nicholas Seward says "no". However, I did the spool first that had the string coming off the bottom (and under the Y-rail) closest to the stepper. If you wound these spools the same, it will be different. I am right handed, so the left-hand spool is what I worked on first. Study it a moment and you will figure it out...
    • If you can energize the stepper you are working on to keep the spool from turning, that would be ideal, but if you are careful not to pull too hard, it should work fine. If you've selected the spool you want to start with, here is the technique: Leave the tape on the spool, and whether you are threading up first or across first, just be sure you pick the string so in the end it comes off the "outside" of the spool (i.e., don't cross the strings of a single spool). Carefully thread the string around all of the bearings in the correct order (some may slip out of the bearing grooves while you are threading - that's OK). When the string reaches the peg on the X-gantry, thread it through the drilled hole, and lay the end out of the way. Repeat for the other end of the string coming off the same spool.
    • Hold the loose end of one string coming through the peg, apply and release pressure as you use a small, thin tool (or your fingers) to work your way around the path to make sure the string is in the groove of every bearing. When you have one end done, wrap the string around the peg a couple of times, and put some tape to hold it while you repeat with the other string.
    • Once both ends are properly threaded, remove the tape from the peg, and pull both ends of the string firmly and equally to force the tape off of the spool. Wrap each end around its peg a couple of times (in a direction that feeds the string between the peg and the rail) and tie a knot. Be careful! If your stepper is not energized, the gantry can move or rack while you are pulling (it probably will a little).
    • Repeat the previous three steps for the other spool.
    • Tension the strings. (De-energize your steppers if they are). Tightening on the pegs will not necessarily be in the screw thread direction. You will turn the screw in the direction that will keep the string on the bottom of the top pegs, and on the top of the bottom pegs. That's why the lock nuts. Tension a little bit on each peg and in approximately equal amounts. Note: tensioning on one peg will tighten the string on it, as well as the string on the diagonally opposite peg. (This is actually the same string, remember?). Check for tension by "plucking the string". It should not "thud" or "thunk". You are looking for a medium to medium-high "tone". No need to overdo it. Nicholas Seward runs his at 5 pounds of tension. (I don't know how to measure that).
    • Check the XZ-Gantry for level. If it has racked during tensioning, adjust the tensioning to bring it back level.
    • You should be able to remove any supports for the XZ-Gantry now. It will stay in place on it's own, even if the steppers are not energized. (If your steppers are not energized, you should be able to move the gantries and watch the bearings and spools turn.)
    8d: String (and Tension) the Y Plane
    Stringing the Y plane is much easier than the XZ plane, but you will use very similar techniques. (I don't have an image for this step.) You will work from the front and the rear of the printer.
    • Install the print bed assembly and position the center of it to be in-line with the Y-bearing brackets. Align the hole in the zither pin to face the Y-bracket bearings.
    • Once again, don't cross the strings as they come off of the spool. Working from the front, take the string that comes off the "front" of the spool, thread it through the opening in the right Y-bracket, between the bearings in the Y-bracket, then toward the front of the print bed, around both bearings in the front, back to the left Y-bracket, between the bearings, and into the hole in the zither pin. Don't wrap or tie the loose end yet.
    • Working from the back, repeat for the other string, except go around the back of the print bed.
    • Take both ends of the string apply and release pressure while making sure the strings are in the bearing grooves along the full path of the strings. Tug the string ends (together) enough to release the tape on the spool. Wrap the ends of the strings around the zither pin (in opposite directions) one full turn and tie a knot.
    • Tension the string. Turning the zither pin (direction doesn't matter) will tighten the string. Pluck the string at the front or rear of the bed, and adjust tension to your desired musical tone.
    You can cut off excess string now. I would leave a few inches on the Y path in case you need to later put more wraps around the zither pin to maintain tension.

    You will want to check string tension in the system every week or so for the first few months of operation. You'll be able to tell when it no longer needs to be checked.

    8e: Install Hotend, Bowden Tube (PTFE), and Plug Everything In
    • Sandwich the E3DV6 between the pieces of the hotted holder and screw to the X-gantry with the M3x16mm and M3x25mm screws. Put one end of the PTFE tube in the Bowden connector on top of the extruder, feed through the slot in the case top, and put the other end in the Bowden connector on the E3DV6. Cut it to length if it appears too long. (Move the hot end to a low Z position and the far X position. Your tube should make a smooth arc about 4" above the case and shouldn't touch the case near the extruder.)
    • If you haven't already, pre-drill the remaining holes in the top of the case and install the remaining screws.
    • Plug the steppers and the hotend into your controller, plug your controller into the power supply, and plug the power supply into your wall. Important Note: The Y stepper will go into the Y driver, the XZ steppers will go into the X and the Z drivers (random at first). You may need to swap the XZ stepper connections and/or flip the connections on one or both to get proper motion. You may need to flip the connector on the Y stepper to get proper motion. (Directions can also be set in firmware.)
    I don't really have much else to say about your controller. When I built my printer, Nicholas' Marlin hack was the only thing that would run a Core XZ machine, and then only on a RAMPS controller. If I'm not mistaken, since then, Core XZ motion has been implemented in Repetier Marlin, Marlin Kimbra, Smoothieware, and others. I had always wanted to upgrade this to a Smoothieboard, but it works so well, I have yet to find the time. (If you decide you want to use a RAMPS and can't get it working with the other firmware flavors out there, send me a private message through this forum, or email me directly (my email is hidden in the Printed Files folder).

    There are no mounting holes in the case for a controller or power supply. There is room, but drill and cut your holes. Placement and cable management should be done to avoid interference with the motion of the printer. My controller is mounted to the inside front left panel. My power supply sits on the desk beside my printer.

    If you build this printer and notice glaring mistakes in the instructions, please comment in the Discussion tab. Questions are welcome there as well.

    If you read all of this - well Thanks!
    Scotty Orr
    #2 Scotty Orr, Aug 31, 2017
    Last edited: Sep 1, 2017

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