Vision Miner Wiki

Front Idler

This guide covers replacing the front idler bearings on the 22 IDEX V4. The machine has four front idlers � one per belt (two for the Y-axis, two for the toolhead belts). Over time, idlers can wear out, develop flat spots, or start making noise, causing belt vibration and print quality issues.

Safety and Warnings

Warning: WARNING: Turn off the printer and unplug it from the power outlet. Make sure the printer is completely powered off before starting any work.

WARNING: Wait at least 60 seconds after powering off for the capacitors to discharge.

WARNING: Moving parts can pinch fingers. Keep hands clear of the motion system while testing belt movement.

IMPORTANT: The idler screws are installed with threadlocker. They will be stiff to remove � insert the hex screwdriver fully and keep it straight to avoid stripping the screw head.

Tools and Materials

  • 2.5 mm Hex screwdriver (hex wrench) � for belt clamp plate screws
  • 3 mm Hex screwdriver (hex wrench) � for idler screws
  • Replacement idler bearings
  • Threadlocker (we recommend Loctite 243)
  • Guitar tuning app on your phone (for verifying belt tension at 65 Hz after reassembly)
  • Small container or magnetic tray (to hold washers and screws)

Releasing Belt Tension

  1. Locate the belt tensioning knob on the front of the machine for the idler you are replacing.

[Photo: Front panel of the 22 IDEX V4 � belt tensioning knob highlighted in red]

  1. Unscrew the tensioning knob by hand, turning it counter-clockwise. Remove it completely.

[Photo: Tensioning knob being unscrewed from the front of the machine]

  1. Catch the washer behind the knob � it will fall off as you remove the knob. Set the knob, spring, and washer aside.

[Photo: Washer falling out from behind the tensioning knob � close-up of washer, spring, and knob laid out on the table]

Freeing the Belt

  1. Release the belt from its clamp so it is no longer looped around the idler:

    • Y-axis belt: Slide the belt out from under its clamp.
    • Tool belt (Tool 0 / Tool 1): Loosen the four screws on the belt clamp plate at the back of the toolhead and pull the belt free.

    For detailed clamp plate instructions, see the Belt Replacement Guide.

[Photo: Belt freed from the clamp � belt hanging loose, no longer looped around the idler]

Securing the Tensioner

  1. Place the washer back onto the tensioning knob shaft.

[Photo: Washer placed on the tensioning knob shaft]

  1. Screw the tensioning knob back in clockwise, almost all the way in. This holds the idler assembly firmly in place so you can unscrew the idler bolt without the assembly moving.

[Photo: Tensioning knob screwed almost all the way in � idler assembly held firmly]

Removing the Idler

  1. Insert the 3 mm hex screwdriver into the idler screw. Push it all the way in and keep it straight � the screw has threadlocker and will resist.

[Photo: 3 mm hex screwdriver fully inserted into the idler screw � straight alignment emphasized]

  1. Unscrew and remove the screw. It is stainless steel with threadlocker applied � expect firm resistance.

[Photo: Idler screw being removed with 3 mm hex screwdriver � firm grip shown]

Warning: IMPORTANT: If the screw feels like it won't budge, do not tilt or wobble the hex screwdriver. Re-seat it fully and apply steady force. Stripping the hex head makes removal much harder.

  1. Pull the idler out. Note the two small M5 washers � one on each side of the idler, acting as spacers. Do not lose them.

[Photo: Idler removed � one M5 washer on each side visible, all three components (screw, idler, two washers) laid out]

Installing the New Idler

  1. Place one M5 washer on one side of the new idler bearing.

[Photo: M5 washer placed on one side of the new idler bearing]

  1. Position the idler in the mounting slot with the washer in place. Add the second M5 washer on the other side.

[Photo: New idler seated in the mounting slot � M5 washers visible on both sides]

  1. Apply a small amount of threadlocker to the screw threads.

[Photo: Threadlocker being applied to the idler screw threads � small drop visible]

  1. Insert the screw through the washers and idler. Tighten firmly with the 3 mm hex screwdriver.

[Photo: Screw being tightened through the new idler with the 3 mm hex screwdriver]

  1. Spin the idler by hand. It should rotate freely with no grinding or resistance.

[Photo: Finger spinning the newly installed idler to verify free rotation]

Reassembly

  1. Turn the tensioning knob counter-clockwise to release the tensioner so the belt can be routed around the new idler.

[Photo: Turning the tensioning knob]

  1. Route the belt back around the new idler and re-clamp it:

    • Y-axis belt: Slide the belt back under its clamp. Make sure it sits flat � not twisted or bunched.
    • Tool belt (Tool 0 / Tool 1): Feed the belt ends back into the clamp plate and tighten the four screws in a cross pattern.

    For detailed clamp plate instructions, see the Belt Replacement Guide.

[Photo: Belt routed around the new idler and re-clamped � belt sits flat with no twists]

Setting Belt Tension

  1. Set the belt tension to 65 Hz using a guitar tuning app. For the full tensioning procedure, see the Belt Tensioning Guide.

Warning: IMPORTANT: The spring inside the tensioner must not be fully compressed. The knob should sit roughly flush with the tensioner screw � this leaves room for the spring to absorb slack over time.

  1. If replacing multiple idlers, repeat the entire procedure (steps 1�17) for each one.

  2. Slide the gantry and toolheads manually across their full range of travel. Movement should be smooth with no binding or unusual noise.

[Photo: Manually sliding the gantry front-to-back and toolheads left-to-right to verify smooth motion]

Troubleshooting

  • Issue: Idler screw won't budge.
  • Cause: Excess threadlocker bonding the screw in place.
  • Solution: Make sure the 3 mm hex screwdriver is inserted all the way in and perfectly straight. Apply steady, firm force � do not wobble it. If the hex head strips, the screw and mounting may need to be replaced as a unit.
  • Issue: Idler does not spin freely after installation.
  • Cause: Screw overtightened, or washers are missing/misaligned.
  • Solution: Loosen the screw slightly. Verify both M5 spacer washers are in place � one on each side of the idler.
  • Issue: Belt tension won't reach 65 Hz after idler replacement.
  • Cause: Belt may have shifted out of its clamp during the process, or the tensioner spring is not seated correctly.
  • Solution: Verify the belt is fully seated under its clamp. Check that the spring is in the tensioner housing and the washer is in place behind the knob. See the Belt Tensioning Guide for the full procedure.

FAQ

Do I have to replace all four idlers at once?

No. Replace only the idlers that are worn or damaged. The procedure is the same for each one.

Can I reuse the old screws?

Yes, as long as the hex head is not stripped. Clean off the old threadlocker residue and apply fresh threadlocker before reinstalling.

What happens if I lose one of the M5 spacer washers?

The idler will sit off-center and may contact the frame or not align with the belt. You need both washers per idler � source replacements before reassembling.

Do I need to remove the belts to replace the idlers?

Yes � the belts must be freed from their clamps so they are no longer looped around the idler. This allows the tensioner to be screwed back in firmly, holding the idler assembly in place while you remove the idler screw. The belts are re-clamped during reassembly.

Support

Vision Miner Support

On this page

Safety and Warnings
Tools and Materials
Releasing Belt Tension
Freeing the Belt
Securing the Tensioner
Removing the Idler
Installing the New Idler
Reassembly
Setting Belt Tension
Troubleshooting
FAQ
Do I have to replace all four idlers at once?
Can I reuse the old screws?
What happens if I lose one of the M5 spacer washers?
Do I need to remove the belts to replace the idlers?
Support

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