Adjusting Spring loom harness heights

Good for both Spring 1 and Spring 2

Why might you need to adjust harness heights?

If you find that your shed is split—meaning the upper or lower shed is uneven and some threads sit slightly higher or lower than others—this usually indicates that one or more lams are not reaching or holding the correct height relative to the rest.

Before adjusting anything, check each shaft to ensure no heddle has slipped off the end and is catching.

Begin by inserting the blocking pin. Examine the upper and lower lams: they should slope gently downward from back to front, and they should all follow this same even slope. Adjust any lams that do not align with this profile. Once finished, remove the blocking pin and open a shed using the same treadle. Has the shed improved? If not, continue below.

For a split upper shed – Identify a warp thread sitting lower than the surrounding threads. Determine which shaft controls that thread and note the shaft number. Look for any other shafts that appear too low.

Insert the blocking pin. In this case, you will need to raise the upper lam for that specific shaft. The upper lams should slope downward from back to front; adjust the lam upward to compensate.

Remove the blocking pin and press the same treadle to check the shed again. Has the split improved? Repeat as needed.

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If you determine that your harness and lam heights require more detailed adjustment, follow these steps:

Insert the blocking pin. Always, always, always.

Look at your harnesses and lams. Use a level to check that they are horizontal.

Adjust as needed.

Adjusting shafts can be done in two ways:

1. Fine adjustments – Turn the white knurled nut.

   • Unscrew to raise the shaft

   • Screw in to lower the shaft This method adjusts height by approximately 5–8 mm.

2. Larger adjustments – Remove the shaft-end bolt from the Texsolv cord and reinsert it into a loop that is higher or lower (or several loops, if needed).

A helpful trick for large adjustments is to loosen the cord first:

• Disconnect the side of the shaft or lam bar you need to adjust. It simply snaps in and out.

• Note the current position of the shaft-end bolt (leave it in place for now; no need to mark the cord).

• Go to the top of the castle and remove the shelf.

• Identify the Texsolv cord for the shaft you are adjusting.

• Locate the Texsolv peg anchoring the end of that cord.

• Remove the peg and loosen the cord by 2–3 loops. Keep track of how many loops you loosen—you’ll need this to restore tension later.

• Reinsert the peg so the cord is now looser.

• Carefully remove the shaft-end bolt, noting which loop you are removing it from.

• Insert the bolt into the new loop you identified earlier.

• Return to the top of the loom and re-tighten the cord by replacing the Texsolv peg in its original hole.

• Repeat for any additional cords requiring adjustment.