7. Y-carriage & Heatbed assembly

Relevant for:

MK4

Last updated a month ago

Difficulty

Moderate

Steps

Available languages

Step 1 Tools necessary for this chapter

⬢For this chapter, please prepare:

⬢1.5mm Allen key

⬢2.0 mm Allen key

⬢2.5mm Allen key

⬢Torx T8/10 key

⬢Needle-nose pliers

⬢Phillips screwdriver PH2

⬢Universal wrench

Step 2 Heatbed cable assembly: parts preparation

⬢For the following step please prepare:

⬢Heatbed MK52 24V (1x)

⬢Heatbed cable red (1x)

⬢Heatbed cable black (1x)

⬢M3x10 screw (2x)

⬢M3w washer (2x)

⬢M3nN nut (2x)

Step 3 Heatbed cable assembly (part 1)

⬢IT IS IMPORTANT to connect the power cable correctly. Before you start the assembly have a look at the pins. The one on the left with "GND" sign must be connected to the BLACK WIRE.

⬢Take both Heatbed cables. Note the label on each cable. For the following steps, prepare the ends of the cables without the label.

Step 4 Heatbed cable assembly (part 2)

⬢Place the black wire above the pin with "GND" sign. Use the end of the cable that is not labeled with QR code. The QR code must be at the other end.

⬢Place the M3w washer above the round cable connector.

⬢Press the M3x10 screw through all parts.

⬢Hold the screw and carefully turn the heatbed upside down.

⬢Attach the M3nN nut onto the M3x10 screw and tighten it slightly.

⬢Turn the heatbed back around. Using the universal wrench and the Allen key, tighten up the screw. We will adjust the cable position later on, therefore do not tighten the screw too firmly yet.

Step 5 Heatbed cable assembly (part 3)

⬢Repeat this procedure for the second (Red / + / VCC) wire. Use the end of the cable that is not labeled with QR code. The QR code must be at the other end.

Before proceeding further, please check again that:

⬢BLACK wire must be connected to the "GND"

⬢RED wire must be connected to the "VCC"

⬢The cable cover, which will be applied later requires the connectors to be slightly inclined towards each other. Press them gently, but leave a gap between them.

Now, tighten both screws firmly using the Allen key and the wrench. Maintain the position of the connectors while tightening.

Step 6 Covering the heatbed cables: parts preparation

⬢For the following steps, please prepare:

⬢Nylon 2x380 mm (1x)

⬢heatbed-cable-cover-bottom

⬢heatbed-cable-cover-top

⬢M3x10 screw (3x)

⬢M3n nut (3x)

⬢Textile sleeve 5x350 (1x)

Step 7 Assembling the heatbed-cable-cover-bottom

⬢Insert three M3n nuts into the shaped openings in the heatbed-cable-cover-bottom.

Use the screw pulling technique.

Step 8 Assembling the heatbed-cable-cover: nylon filament

⬢Place the heatbed-cable-cover-bottom like in the picture. Push the heatbed thermistor cable through the heatbed-cable-cover-bottom.

⬢Insert the nylon filament into the hole in the heatbed-cable-cover-bottom. Don't let the nylon filament stick out too much on the other side. It should not protrude more than 2 millimeters.

When inserting the nylon filament, ensure that the filament does not damage the thermistor cables under the printed part.

⬢Orient the curve of the filament as shown in the third picture.

Step 9 Assembling the heatbed-cable-cover-bottom

⬢Slide the cable-cover-bottom under the heatbed cable connectors (M3nN nuts). See the correct orientation in the picture.

⬢Secure the cover with the M3x10 screw from the top. Tighten the screw firmly.

Make sure the nylon filament is still bent upward as in the previous step.

Step 10 Assembling the heatbed-cable-cover-top

⬢Wrap the end of the cable bundle together with the nylon filament in the textile sleeve. Slide the sleeve as far towards the heatbed as possible.

⬢Attach the heatbed-cable-cover-top onto the junction and secure it with two M3x10 screws.

⬢On the bottom side, leave a slack on the thermistor cable for one finger to be pushed through.

⬢Make sure there is no big gap between both covers.

Step 11 Wraping the textile sleeve

⬢Finish wrapping the cable bundle in the textile sleeve. And twist the sleeve, not the cables.

Step 12 Y-carriage: parts preparation

⬢For the following steps, please prepare:

⬢LM8UU bearing (3x)

⬢Y-carriage (1x)

⬢Bearing clip (3x)

⬢Rubber bearing pad 31x16x1 mm (3x)

⬢Plastic bearing pad 31x16x0.5 mm (3x)

⬢M3x8 screw (6x)

Step 13 Lubricating the bearings INFO

⬢To identify if the bearings require lubrication, check the packaging:

⬢Bearings pre-lubricated by Prusa company are shipped in a blue bag. If you have pre-lubricated bearings, go to Assembling the bearing clips.

⬢If your bearings did not come in this specific packaging, the bearings must be lubricated. Proceed to the following steps with instructions for proper lubrication of the bearings.

Step 14 Lubricating bearings: parts preparation

⬢For the following steps, please prepare:

⬢Prusa lubricant applicator (1x)

⬢Prusa lubricant (1x) for LM8UU bearings

⬢Several paper towels to wipe oil and grease from the bearing surface.

Each bearing must be lubricated before mounting on the printer. Follow these instructions carefully.

Step 15 Lubricating the bearing

Use any piece of fabric as a pad to protect your working surface from grease.

Make sure the bearing is clean inside.

⬢Wipe the preservative oil off the bearing surface with a paper towel.

⬢It is necessary to lubricate all 4 rows of balls inside the bearing.

⬢Open the lubricant and pierce the hole in the tube with the tip in the cap.

⬢Screw the tube into the applicator.

⬢Carefully slide the entire bearing onto the applicator.

Step 16 Lubricating the bearing

⬢Turn the tube and applicator counterclockwise until you feel a slight resistance. This means that the holes in the applicator are aligned with the ball rows.

⬢Gently press the tube to push the lubricant into the ball rows of the bearing.

⬢Look at the front of the bearing. When the applicator pushes the lubricant out (around the black gasket), stop pressing the tube. Hold the bearing with the other hand during the lubricating.

The grease must be spread evenly over all four ball rows inside the bearing. There must not be too much grease, or too little. Take a closer look at the last picture.

⬢Wipe off excess grease on the outside of the bearing with a paper towel.

⬢Use this procedure for all three bearings.

The bearings may leave excess grease on the smooth rods after their installation. Wipe off any residue with a paper towel.

Step 17 Assembling the bearing clips

⬢Push two M3x8 screws through the bearing clip.

⬢Insert the rubber bearing pad on the screws.

⬢Insert the plastic bearing pad on the screws.

⬢Repeat the same for the remaining two bearing clips.

The order of the pads is crucial. Check the order on all three bearing clips.

Step 18 Installing the bearing on the Y-carriage

⬢Note the three pockets for bearings in the Y-carriage.

⬢Start with the side with the one pocket. Attach the bearing clip on the cutout.

⬢Insert the bearing into the bearing clip.

Step 19 Aligning the bearing

⬢The correct bearing orientation: When placing bearings onto the Y-carriage, make sure that they are oriented as shown in the picture. The tracks (rows of balls) have to be on the sides.

⬢Align the bearing so that it is centered on the bearing clip. Approximately the same piece of bearing should be visible on each side.

⬢Maintain the bearing position and slightly tighten both screws. Just barely to maintain its position and orientation. We will tighten the screws firmly later on.

Step 20 Installing the bearings on the Y-carriage

⬢Attach two bearing clips on the remaining two bearing pockets and push two bearings inside.

⬢Orient both bearings so that the two rows of bearing balls have to be on the sides.

Step 21 Positioning of the bearings

Correct bearing alignment is CRUCIAL. Proceed carefully and make sure that both bearings are as close to the center of the Y-carriage as possible and do not touch any pocket edge.

⬢Unlike the previous single-bearing, position the bearings as close to the center of the Y-carriage as possible. Beware, the bearings must not touch the edge of the pocket!

Incorrect positioning: the bearings must not touch or overlap the edges of the pocket as shown in the bottom of the first picture.

⬢Maintain the bearing's position and slightly tighten the screws. Just barely to maintain the position and orientation of the bearings. We will tighten the screws firmly later on.

⬢After securing the clips double-check the correct position of the bearings so that they do not touch the edges of the pockets.

Step 22 Y-axis: smooth rods holders

⬢For the following steps, please prepare:

⬢Y-rod-holder (4x)

⬢M3x10 screw (12x)

⬢M3nS nut (12x)

⬢Smooth rod 8x330 (2x)

Step 23 Inserting smooth rods into Y-carriage

⬢Using a paper towel, wipe the transport oil from the surface of the smooth rods.

NOW, PLEASE BE VERY CAREFUL! Gently insert the rod straight into the bearings, do not apply too much force and do not tilt the rod!

In case you manage to push out some balls from the bearings by accident, please count the balls. Without one or two balls, the bearing will continue to work. If there are more of them, please consider ordering new bearings.

⬢Tighten the screws on each bearing clip.

After the final tightening, the movement of the smooth rods must be gentle. If the smooth rod moves stiffly, loosen the screws and repeat the procedure.

⬢After tightening all the screws securing the bearing clips, make a final check of the correct position of the bearings:

Two-bearing side: the bearing must be positioned closer to the center of the Y-carriage. It must not touch or extend over the edge of the pocket.

⬢Single-bearing side: the bearing must be in the center of the pocket.

Step 24 Preparing Y-rod-holder

⬢Take one Y-rod-holder and insert two M3nS nuts.

⬢Make sure you've pressed the nuts all the way in. You can use pliers, BUT be careful, you can damage the printed part.

In case you can't press the nuts in, don't use excessive force. First, check if there isn't any obstacle in the nut trap.

⬢Insert one M3nS nut from the side of the Y-rod-holder.

⬢Ensure and adjust the alignment of each nut with the 2mm Allen key.

⬢Repeat for the remaining Y-rod-holders.

Step 25 Mounting the Y-rod-holder parts

⬢Push one of the Y-rod-holders onto the rod. Align the front surface of the plastic part with the flat surface of the rod.

⬢Check the correct position of the Y-rod-holders. The screw hole must be facing up and towards the center of the Y-carriage (see the picture).

⬢Repeat for the remaining Y-rod-holders.

Step 26 Installing the Y-carriage

⬢Take the Y-carriage including smooth rods with rod holders and place them in YZ-frame. Make sure, that two bearings are on the left side (see the picture, there are two pairs of the screw holes on the left and one pair on the right).

⬢Secure each Y-rod-holders and fix them with M3x10 screws on the front plate (the one with the longer extrusions). Tighten both screws equally, but not completely. We will tighten them fully later on.

⬢Insert the M3x10 screw into the hole in each front holder and tighten them.

⬢Secure the second pair of the Y-rod-holder with two M3x10 screws. Tighten both screws equally, but not completely. We will tighten them fully later on.

⬢Insert the M3x10 screw into the hole in each rear holder and tighten it.

In case the M3nS nuts keep falling out, please flip the frame upside down. Tighten both printed parts and then return the frame to the original position.

Step 27 Aligning the smooth rods

IMPORTANT: proper alignment of the smooth rods is crucial to reduce noise and overall friction.

⬢Move the Y-carriage back and forth across the entire length of the smooth rods to align them.

⬢Then move the carriage to the front plate and tighten all screws in the front-Y-holders.

⬢Move the Y-carriage to the rear plate and tighten all screws in the back-Y-holders.

Step 28 Assembling the Y belt: parts preparation

⬢For the following steps, please prepare:

The printed parts are not the same, take a closer look a compare both parts with each other.

⬢Y-belt-tensioner (1x) with an oval hole

⬢Y-belt-holder (1x) with a hexagonal hole

⬢M3x40 screw (1x)

⬢M3x10 screw (4x)

⬢M3nN nut (1x)

⬢GT2-20 pulley (1x)

⬢Pin H8 2.9x20 (1x)

⬢Y belt (1x)

Step 29 Assembling the Y-belt-holder

⬢Insert the M3nN nut all the way into the Y-belt-holder.

Use the screw pulling technique. Attach the M3nN nut on the tip of the M3x40 screw (a few turns are enough). Do not tighten the screw, pull the nut all the way into the Y-belt-holder. Don't forget to remove the M3x40 screw from the part and keep it aside for later use.

Step 30 Assembling the Y belt

⬢Lean the printer onto the right side (the one with the PSU) to gain access to the bottom.

⬢Push the pin into the pulley and center it.

⬢Take one of the Y belt ends and push it into the Y-belt-holder. Note the orientation of the belt (teeth).

⬢Secure it by inserting and tightening the M3x10 screw.

Step 31 Attaching the Y belt holder

⬢Using the M3x10 screw, fix the Y-belt-holder to the Y-carriage. Use the left (rear) hole in the center part.

Tip: pre-screw the screw into the Y-belt-holder before attaching it to the Y-carriage.

⬢Guide the Y-axis belt around the Y-axis motor pulley. Make sure the belt is inside the frame, not under!

⬢Take the free end of the Y belt guiding from the pulley and push it into the groove in the Y-belt-tensioner.

⬢Secure it with the M3x10 screw.

Step 32 Assembling the Y belt tensioner

⬢Take the free end of the belt and guide it around the GT2-20 pulley.

⬢Insert the belt with the pulley into the Y-belt-idler on the rear of the front plate.

⬢Push the pulley all the way inside the printed part and lightly pull on the belt to lock the pulley in place.

Step 33 Attaching the Y belt tensioner

⬢Insert the M3x10 screw into the Y-belt-tensioner and try if the screw reaches the threaded hole in the Y-carriage when tensioning the belt.

If the screw does not reach the hole, it is necessary to remove the Y-belt-holder (the one already installed) and reposition the belt by one tooth in both printed parts - one tooth in each printed part will be vacant.

⬢Attach the Y-belt-tensioner to the right (front) hole in the Y-carriage and secure it with the M3x10 screw. Do not overtighten the screw. We will adjust the exact position later on.

⬢Insert the M3x40 screw into the Y-belt-tensioner and tighten it until the screw reaches the nut in the second part.

Step 34 Tensioning the Y belt

⬢Move the Y-carriage all the way to the back. Using a finger on your left hand, push the belt down. A medium force should be needed to squish the belt until both the parts touch. Don't try to overstretch the belt as you might damage the printer.

⬢You can change the belt tension by adjusting the long M3x40 screw on the bottom of the Y-carriage.

⬢Tighten the screw to bring the parts closer together and increase the tension.

⬢Release the screw to move the parts apart to
decrease the tension.

⬢After you set the correct belt tension, tighten up the M3x10 screw on the bottom to fix the Y-belt-tensioner in place.

Step 35 Belt tension check

This step is recommended, but optional. If you don't have a phone at your disposal, continue to the next step. You can do this check later on.

⬢To verify or fine-tune the X or Y-axis belt tension on your printer, visit prusa.io/belt-tuner and open up the webpage on your mobile device. Or using your phone, scan the QR code in the picture.

⬢Watch the instructional video on prusa.io/belt-tuner-video and fine-tune your Y belt tension, if required.

The belt tuner app was tested on multiple phones and should work across all most common phone manufacturers. However, in some rare cases it might not work as expected. Please state your brand and model in the comments below the step.

Step 36 Aligning the Y belt

⬢Make sure that both the top and bottom parts of the belt are parallel (directly above each other).

⬢If not, adjust the belt position. Release both screws on the pulley and slightly move with it, until you reach the best position.

⬢Tighten both screws on the pulley.

Step 37 Installing the Expansion joints: parts preparation

⬢For the following steps, please prepare:

⬢Expansion joint (8x)

⬢M3x6r screw (8x)

Step 38 Preparing the expansion joints

⬢Install eight M3x6r screws in the outer holes on the Y-carriage. Do not tighten them completely. A few turns are enough for now.

Step 39 Installing the Expansion joints

The installation of the expansion joints needs to be done carefully. It is crucial for the correct functionality of the printer. Carefully read the instructions:

⬢Slide the expansion joint from the side on the M3x6r screw.

Make sure the expansion joints are correctly oriented. There is a recess with approximately the same shape as the expansion joint. The joint must fit into the recess. See the second picture.

⬢Maintain the position and tighten the M3x6r screw using the 2.0mm Allen key.

⬢Proceed the same for the rest of the expansion joints.

Step 40 Attaching the heatbed: parts preparation

⬢For the following steps, please prepare:

⬢M3x4bT screw (8x)

⬢M3x14bT screw (1x)

⬢Spacer 6x3.1x8 mm (1x)

⬢In some older packages this part is called "Spacer 5.5 mm".

Step 41 Attaching the heatbed

⬢Place the spacer onto the Y-carriage and align it with the hole in the center.

⬢Put the heatbed on the Y-carriage and secure it by the M3x14bT. Do not fully tighten the screw yet.

⬢Insert the M3x4bT screws into the remaining holes in the heatbed. Do not fully tighten the screws yet.

Step 42 Tightening the heatbed

⬢After all screws are in place, tighten them in the following sequence:

⬢Center screw

⬢First four screws (edges)

⬢Last four screws (corners)

Tighten the screws gently, but firmly.

Step 43 Guiding the heatbed cables: parts preparation

⬢For the following steps, please prepare:

⬢Heatbed-cable-holder (1x)

⬢M3x6 screw (2x)

⬢Power terminal screw 6/32" (2x)

Step 44 Guiding the heatbed cables

⬢Push the heatbed cables and heatbed thermistor cable through the square opening on the back of the xBuddy Box.

⬢Push the filament through the circle hole right below the square opening.

⬢Place the black heatbed cable on the left terminal and secure it with the terminal screw.

⬢Place the red heatbed cable on the right terminal and secure it with the terminal screw.

⬢Connect the heatbed thermistor cable to the xBuddy board.

Step 45 Covering the heatbed cables

⬢Attach the heatbed-cable-holder to the xBuddy box. The cable bundle must be pointing up. Secure it by tightening both M3x6 screws firmly.

Step 46 Verify all connections once more!

⬢Check your electronics connection with the first picture.

Before covering the electronics, check and compare your wiring.

⬢Compare your cable management with the third picture.

Make sure that all connectors are fully inserted and PSU cables properly tightened. Otherwise, there is a risk of damage to the printer!

Step 47 Installing the ESP module: parts preparation

⬢For the following steps, please prepare:

⬢ESP-01S Wi-Fi module (1x) packed in black plastic packaging

⬢M3x6 screw (1x)

⬢Wifi-cover (1x)

Step 48 Installing the ESP module

Be very careful when handling and connecting the ESP module to avoid bending and damaging the pins.

⬢Grasp the ESP Wi-Fi module by the edges of the board and plug its pins in the eight-hole slot in the xBuddyBox. Make sure the part is correctly oriented.

⬢Cover the ESP module with the wifi-cover.

⬢Secure it with the M3x6 screw.

Step 49 Covering the xBuddy box: parts preparation

⬢For the following steps, please prepare:

⬢xBuddybox-cover (1x)

⬢M3x6 screw (4x)

⬢El-box-cover (1x)

⬢M3x10 screw (2x)

Step 50 Covering the xBuddy box: bottom cover

⬢Push two M3x10 screws through the el-box-cover.

⬢Attach the cover to the xBuddy Box. There are two threaded holes in the xBuddy box. Make sure there is no cable in the way for the screws and the cover.

⬢Secure the el-box-cover by tightening both M3x10 screws to the xBuddy box.

Step 51 Covering the xBuddy box

⬢Align the xBuddy box cover with the xBuddy box and secure it with four M3x6 screws.

Step 52 Assembling the double spool holder (part 1)

⬢For the following steps, please prepare:

⬢Centre part (1x)

⬢Side arm (2x)

Step 53 Assembling the double spool holder (part 2)

Don't use excessive force during the assembly, or you might damage the spool holder locking system.

⬢Place all three parts in front of you. Note both "arms" are identical. Make sure the C shaped part, which will snap on the printer's frame is facing towards you.

⬢Take the "arm" on the right side, insert it gently in the main part and start to rotate clockwise (away from you). It should take about half the turn to lock the part in place.

⬢Take the "arm" on the left side, insert it gently in the main part and start to rotate anticlockwise (towards you). It should take about half the turn to lock the part in place.

The assembly requires a very small force (torque). If you experience issues, check first the locking mechanism for obstacles.