> ## Documentation Index
> Fetch the complete documentation index at: https://stem-docs.intellectualpoint.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Filament feeder on the bar

> Mount the filament feeder (the QR-code block) onto the long extruder bar.

## Building the extruder bar

Now you start assembling the **extruder bar** - the horizontal rail that will carry your print head. First you mount the **filament feeder** (the chunky block with the QR code) onto the long bar. This step is a little fiddly, so take your time.

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<Info>
  For this step you need the **two M4x16 screws** (black) and the **number 3 Allen wrench**. You will also unwrap the two remaining rails and use the **longer** one as the extruder bar.
</Info>

## Step-by-step

<Steps>
  <Step title="Unwrap and pick the longer rail">
    Cut the cellophane off the last two rails. One is slightly longer - the **longer rail is your extruder bar**. Set the shorter one aside for later.
  </Step>

  <Step title="Find the correct side of the bar">
    The bar has a **big hole / small hole / small hole** side with a **machined groove**. That groove side must face up and align with the nut on the filament feeder.
  </Step>

  <Step title="Sandwich the feeder and bar">
    Set the feeder with the QR code facing up, lay the bar's machined groove over the feeder's nut so it sits flush, then flip the assembly over so you can reach the two screw holes.
  </Step>

  <Step title="Screw the feeder to the bar">
    Push the two **M4x16** screws up through the holes into the bar. Thread each with the number 3 Allen wrench - you may need to jiggle the bar to align the holes. Take your time, then tighten both.
  </Step>
</Steps>

<Tip>
  This is one of the trickier steps - the screw holes can be hard to line up. If it fights you, loosen slightly, nudge the bar until the hole and screw meet, then thread it in. Patience wins here.
</Tip>

<Check>
  The filament feeder is bolted firmly to the longer bar with both M4x16 screws, the QR code faces out, and the feeder's click switch presses freely.
</Check>

## Up next

Next you slide the **extruder carriage** (the print head) onto this bar.