Table of Contents
Primer: What This Setup Achieves—and When to Use It
Correct threading sets up stable thread delivery and prevents avoidable issues like thread breakage. On the Tajima SAI, the upper thread must follow a defined path—from the spool, through its tube, the tension system, the take-up lever, and finally the needle and under the presser foot. The under thread (bobbin) must be installed clockwise in its case, with tension verified using the built-in swing test.
When to use this guide
- First-time machine prep
- After changing colors or re-threading needles
- After cleaning or maintenance that required de-threading
Quick check
- You can identify thread positions No.1–No.8 and know that the sequence runs counterclockwise from the front right.
Prep: Tools, Materials, and Workspace
Tools and accessories
- Upper thread guide (accessory) for feeding each thread through its tube
- Threader (accessory) for the needle eye
- Bobbin-case-use flat head screwdriver for bobbin tension adjustment
Materials
- Upper thread spools
- Bobbin wound with under thread
Workspace
- Clear and organized area around the machine so you can access the thread tubes, tension discs, take-up lever, needle area, and bed cover comfortably
Pro tip
- Keep all threads within reach and unspooled just enough to route them smoothly; excessive slack can snag.
Checklist — Prep
- Upper thread spools ready and nearby
- Accessory thread guide and needle threader at hand
- Bobbin(s) pre-wound and within reach
- Flat head screwdriver for the bobbin case available
Setup: Thread Paths and Why They Matter
Every contact point you pass—tube, thread presser, tension discs, take-up lever, lock shaft, needle clamp—controls how the thread feeds. If any link is missed or out of order, the machine cannot regulate tension consistently.
- Upper thread numbering: No.1 to No.8, counterclockwise from the front right.
- Travel direction confirmation: An arrow printed around the thread breakage detection disk indicates the correct upper thread travel direction during final checks.
Watch out
- Skipping the tension discs or threading the needle incorrectly can cause thread breakage. If in doubt, repeat the path carefully.
Operation: Step-by-Step Threading (Upper and Under)
Follow these steps in order. The expected outcome follows each step so you can validate as you go.
1) Load upper thread spools
- Place each upper thread spool onto a designated thread stand.
- Ensure spools align with the machine’s numbering: No.1 through No.8 arranged counterclockwise from the front right.
Expected result: All upper thread spools are correctly positioned according to the numbering system.
2) Guide each upper thread through its tube
- Hook the thread end onto the tip of the accessory upper thread guide.
- Insert the guide from the opposite side into the thread tube.
- Pull the thread through until it emerges from the other end.
Expected result: Each thread exits its tube and pulls smoothly with light tension.
Pro tip
- If you need to reposition spools later, re-confirm the No.1–No.8 order before threading downstream components. tajima embroidery hoop
3) Thread the tension system
- Lift the thread pressing shaft to open the path.
- Pass the thread through the first thread presser, through the tension discs, and then through the second thread presser.
Expected result: The thread lies neatly between the tension discs and moves smoothly when gently tugged.
Quick check
- With light pulls, you should feel consistent resistance; if the thread snags before the discs, re-seat it.
4) Route the upper thread to the take-up lever
- Place the thread along the center thread course, following the groove on the top cover.
- Feed the thread through the hole in the take-up lever.
- Guide the thread down along the groove toward the needle area.
Expected result: Thread is secure in the groove and properly seated through the take-up lever.
Decision point
- If you are threading multiple needles, complete this path for each before moving on to needle threading, or thread one needle from start to finish before proceeding to the next—use whichever method helps you keep track accurately. hooping station for embroidery
5) Thread the needle and position under the presser foot
- Pass the thread through the lock shaft and then the needle clamp.
- Thread the needle eye. If using the threader, orient it with the triangle mark up, insert the thread sideways, slide to the needle groove while pushing, and push the thread into the needle eye.
- Pull the thread backward from the needle eye using the hook of the threader.
- Position the thread under the presser foot.
Expected result: Thread is firmly through the needle eye and sitting under the presser foot.
Watch out
- Improper threading through the needle eye can cause thread breakage during embroidery. Re-thread carefully if you feel resistance or see fraying.
6) Confirm upper thread path and secure
- Observe the arrow around the thread breakage detection disk and confirm your thread path aligns with that indicated direction.
- Replace the thread pressing shaft and press down until it clicks into place.
Expected result: All threads follow the arrow direction, and the thread pressing shaft audibly clicks, locking the system.
7) Prepare the under thread (bobbin)
- Open the front cover of the bed.
- While holding the latch lever, remove the bobbin case from the rotary hook.
- Insert the bobbin into the case so the under thread winding direction is clockwise.
- Hold the thread end, guide the under thread through the slit in the bobbin case, and lead it to the spring edge.
- Pull out about 5 cm of under thread from the bobbin case.
Expected result: Bobbin is seated in the case, thread exits via the slit to the spring edge, and ~5 cm tail is available.
Quick check
- Pull the under thread: the bobbin should rotate in the opposite direction, confirming correct orientation in the case.
8) Insert the bobbin case and close
- Place the bobbin case into the rotary hook and listen for a click.
- Close the front cover of the bed.
Expected result: Bobbin case is locked in with a clear click; front cover is closed.
9) Adjust under thread tension (if needed)
- Suspend the bobbin case by holding the end of the under thread and gently swing it.
- If the under thread releases slowly, the tension is appropriate. If not, turn the bobbin case tension screw with the small flat head screwdriver in small increments and retest.
Expected result: Under thread releases slowly during the swing test, indicating correct tension.
Checklist — Operation
- Upper threads loaded No.1–No.8 counterclockwise
- Each thread routed: tube → presser → tension discs → presser → top groove → take-up lever → lock shaft → needle clamp → needle eye → under presser foot
- Thread pressing shaft clicked into place
- Bobbin inserted clockwise, thread through slit to spring edge, 5 cm tail
- Bobbin case clicks into the rotary hook; swing test passes
Quality Checks: How to Know It’s Right
Upper thread path
- Visual: Thread sits cleanly in the top cover groove and the take-up lever hole.
- Feel: Gentle, consistent resistance through the tension discs—no snagging before or after the discs.
Needle and presser foot
- The thread passes through the needle eye without fraying and lies under the presser foot.
Thread direction confirmation
- The arrow around the thread breakage detection disk matches the direction your upper thread will travel.
Under thread
- Orientation: Bobbin installed clockwise in the case.
- Swing test: When suspended by the thread, the under thread should release slowly; adjust only if necessary. magnetic embroidery hoop
Quick check
- After closing the bed cover, tug the bobbin tail gently—steady, smooth release confirms the case is seated and tension is near-correct.
Results & Handoff: Ready to Stitch
When you finish these steps, the Tajima SAI is fully prepared for embroidery:
- Upper thread paths are secured and tensioned.
- Needles are threaded and threads positioned under the presser feet.
- Bobbin is oriented clockwise with verified tension and seated with a click.
From here, you can proceed to hooping and test stitching for your design on the SAI. If you frequently rehoop or handle multiple placements, consider planning your hooping workflow for repeatability and speed. embroidery hoops magnetic
Pro tip
- Thread multiple needles in a consistent order (e.g., 1 to 8) every time—this habit reduces errors and speeds up recovery if you need to re-thread mid-project. magnetic hoops for tajima embroidery machines
Troubleshooting & Recovery
Symptom: Thread breaks at the needle
- Likely cause: Missed path through the needle eye or preceding guides; or improper seating in tension discs.
- Fix: Re-thread through the lock shaft, needle clamp, and needle eye. Confirm thread sits correctly in both thread pressers and the tension discs. tajima magnetic hoops
Symptom: Uneven stitches on the underside
- Likely cause: Under thread tension off.
- Fix: Perform the swing test; adjust the bobbin case tension screw slightly with the flat head screwdriver until release is slow and steady. magnetic embroidery hoops for tajima
Symptom: Thread feels too tight or too loose through the tension discs
- Likely cause: Thread not centered in the discs or skipped a presser.
- Fix: Lift the thread pressing shaft, re-seat the thread in presser → discs → presser, then press the shaft down until it clicks. Re-check.
Symptom: Bobbin case doesn’t feel secure
- Likely cause: Case not fully inserted.
- Fix: Remove and reseat the bobbin case into the rotary hook until a clear click is heard; ensure ~5 cm of tail is free before insertion. tajima embroidery hoop
Quick isolation tests
- Upper vs. lower: If top thread looks correct but stitches are loose underneath, start with the bobbin swing test; if that passes, re-inspect the upper thread path.
- Single-needle validation: If threading multiple needles, test one needle’s path end-to-end to confirm the machine is behaving as expected, then apply the same process to the others. magnetic hoops for tajima
Watch out
- Adjust bobbin tension in small increments only. Large turns make it harder to return to a good baseline.
From the bench
- Following the arrow at the thread break detection disk is an easy way to double-check your final upper thread travel before closing the thread pressing shaft.
- The 5 cm bobbin tail gives you enough slack to seat the case cleanly and catch thread on the first stitches.
Recap Checklist
- Upper spools: No.1–No.8, counterclockwise from the front right
- Upper threading: tube → presser → tension discs → presser → top groove → take-up lever → lock shaft → needle clamp → needle eye → under presser foot
- Confirm arrow at thread break detection disk matches travel direction
- Thread pressing shaft clicked into place
- Bobbin: clockwise in case, thread through slit to spring edge, 5 cm tail
- Bobbin case clicked into the rotary hook; swing test releases thread slowly
That’s your Tajima SAI, correctly prepared and ready for clean, reliable stitching. embroidery hoops magnetic