Table of Contents
Industrial Walking Foot
Juki Walking Foot DNU 1541s
Tool Guide
The Setup, Operation, and Cleanup Checklists of this guide are what instructors use to ensure that you can use the equipment according to community expectations.
This machine is intended for use on heavy materials like vinyl, leather and heavy layers of upholstery. The stepping feeding motion promises the consistent feeding of multiple layers or heavy duty materials without stitch gathering or layer unevenness.
Maximum sewing speed is 3,000 stitches per minute!
GENERAL LAYOUT
 | 1. Thread Holders Please Note: The secondary holder is for continual bobbin winding 2. Maintenance Tag Manually tracks the usability status with Green/Yellow/Red cards 3. Knee Presser Foot Lifter: Knee operated lever that lifts the presser foot while sewing 4. On/Off Switch: Main power to the machine 5. Foot Pedal: Controls the speed of the motor |
Tool Anatomy
MACHINE ANATOMY
- Thread Take-up lever - part of the thread feeding mechanism that pulls thread off the spool
- Flat 4-hole Thread Guide
- 2-hole Thread Guide
- Bobbin Winder Tension - ensures uniform winding
- Hand Wheel - Manually advances the machine (turns towards the user)
- Bobbin Winder - pin and lever that spins the bobbin during winding
- Needle
- Check Spring - Keeps the thread taught as the take-up lever moves
- Tensioner - keeps stitches even
- Presser Foot - Holds material down to the bed while sewing
- Feed Dog Mechanism - Moves with presser foot to feed material
- Safety Clutch - Release button for safety lock out mechanism
- Stitch Length Selector - Adjusts size of stitch
- Reverse Lever - to allow back-stitching at the end of seams
CONTROL PANEL
 | 1. On/Off Switch: Main power to the machine 2. Increase Speed: Increase r.p.m. 4. Decrease Speed: Decrease r.p.m. 5. Needle Position Mode: Set the needle to up / down position 6. Rotation: FOR AUTHORIZED MAINTENANCE ONLY |
Tool Safety
COMMON HAZARDS
The most common hazards are thread jams and broken needles. Watch for binds, jams, and bird nests—stop immediately if they occur.
- This machine has a safety mechanism to avoid jamming. It must be reset after a jam before continuing. (See troubleshooting guide)
- Ensure the needle and thread are removed before winding a bobbin
- Avoid pulling/pushing fabric, which may misalign and break the needle
The most significant hazard is injury. Always power off and run the machine until the motor drains before handling, adjusting, or threading.
- Keep fingers 3” away from the needle
- Power off and drain the motor before:
- Threading
- Replacing needles
- Removing jams
- Tie back hair and scarves
- Tuck sleeves behind elbows
PROHIBITED MATERIALS
Thread Jams and needle breakage are critical concerns. Material that is too thick or rigid will lead to needle breakage. Material that is too slick (plasticized or otherwise “finished”) will slide against the presser foot and cause thread jams and/or needle breakage.
Industrial machines will not “step over” pins in the fabric. Hitting one will break the needle and send broken parts into the hook below.
For those reasons, it is important to avoid:
- Abrasives
- Paper and cardboard products
- Pins in the fabric
- Plastics
- Rigid Material (non-fabric)
Initial Setup
| SETUP CHECKLIST 1. Wipe down the machine and bed to clean up any oil or dust 2. Power on the machine 3. Ensure safety is not engaged, if the machine seems to be jammed, see Troubleshooting. 4. Wind the bobbin 5. Power off the machine to insert the bobbin and thread the machine 6. Ensure the needle is usable and appropriate for the material and thread. 6. Set the needle position 7. Begin operation |
CONSUMABLES
Appropriate needles and bobbins are available in the consumables section of our store front. Both are sold individually for ease and convenience.
Members are responsible for bringing their own thread and fabric.
- Bobbins: Size “M”, standardized metal bobbin
- Thread
- Must be in a Cone or Vicone to accommodate high speed
- Always use the same thread in the upper tension and in the bobbin
- Fabric: light to heavy weight fabrics
- Needle (see chart below):
- Size Range for machine: 135 x 17, 135 x 16 (Nm160) Nm125～Nm180
- Point Type: appropriate to fabric
- Eye: must be 40% larger than the thickness of the thread
| - Walking foot needle 135 x 17, 135 x 16 (Nm160) Nm125～Nm180 | |||
| b. Needle Type (shape of the point) | c. Needle SIze (Fine to heavy) | Fabric Type | Thread Size (Measured in Tex, Denier, mm and weight) |
| Universal R or DP | 70 up to 230 | Light to heavy woven | Light to medium |
| Ballpoint RG, FFG, G | 100 to 125 | Light to medium knits, jerseys, stretch, bulky knit | Light to medium |
| Jeans R | 100 - 110 | Medium to Heavy | Medium to Heavy |
| Leather/Vinyl LR, LL, P, PCL, S, D, GH | Range of sizes | Heavy/Layers | Heavy |
NEEDLE ANATOMY
CHECKING NEEDLE SIZE
- Grab a needle and about 12 inches of the intended thread
- Thread the needle
- Hold both ends of the thread, creating a 60 degree slope with one end to see if the needle is able to slide along the slope
- Reverse the process to see if the needle slides back
If the needle does not freely slide down the thread, the size may be too small. As a general rule, you’ll want the smallest size needle that will slide freely down the thread.
WIND THE BOBBIN (Size M)
- Check the bobbin housing for lint, brush it out if necessary.
- Pass the thread in order of (1) through (4)
- Lift the manual presser foot lever to raise the presser foot.
- Gently push the foot pedal until the bobbin is full—it shuts off automatically.
Please Note: If the bobbin is lop-sided, it can be used with caution, although it can affect tension. Please flag the machine with a yellow tag, and submit a maintenance request
ATTACH BOBBIN CASE
 | Set the bobbin into the bobbin case. Pass the thread around the thread slit (1), and pass it under the tension spring (2) Adjust so that the bobbin rotates in direction B when thread is pulled in direction A |
 | Orient the lower knob (1) of the bobbin case to the indented part (2) of the bobbin housing’s inner hook. Push the bobbin case until it clicks. |
INSERT NEEDLE
 | Turn the handwheel forward until the needle bar is at the highest position - Loosen the needle clamp screw and hold the needle so that scarf is to the right and the long groove in the needle is exactly to the left. - Insert the needle (1) into the clamp hole until it will go no further. - Tighten the needle clamp screw firmly (monkey tight—not gorrilla!) |
THREAD THE MACHINE
Thread the machine following the order of (1) through (13) as shown above.
Move the handwheel towards you, never away to get the top thread to take up the bobbin thread.
CRITICAL THREADING DETAILS
 |  |
| Ensure the presser foot is UP. While holding the thread taught on either side, pass the thread between the tension discs, between the spring guide, and above the spring. You will hear a light click as the thread crosses over a small hook on the inside of the disc. (just visible through the hole next to the spring) | Please Note: Do not adjust the check spring knob (#6)! Its function is to keep the thread taught while the take up arm moves to the highest position. Loosening the nut will disable the spring, causing the machine to come unthreaded or tangle while sewing. This spring should always have enough tension to pull the thread down. |
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| Down through and under the next two guides and the bottom slot, then through the hole above the needle
Basic Operation
SETTING THE NEEDLE POSITION
Setting the needle position allows you to control whether the needle will finish a stitch engaged in your fabric or not. A light press and release of the foot pedal will move the needle exactly one stitch forward, ending the needle in the desired position setting.
  | Click  for 1 quick second to see the current setting (up or down).Do not hold the button for more than 1 second to avoid restoring to factory settings. The current setting (up or down) will flash across the screen. To change the setting, click again. The opposite setting should flash across the screen. |
ADJUSTING THE TENSION
To increase the tension, turn the tension nut (1) clockwise (A). To reduce the tension, turn the tension nut (1) to the counterclockwise (B).
 |  |  |
| Normal tension for straight stitch sewing. | Too loose for straight stitch sewing. | Turn the dial clockwise to increase tension. |
BACK STITCH/REVERSE SEWING
 | Press down the reverse feed control lever (1). Release the lever and the machine will run in the normal feed direction |
SAFETY RESET
This machine has a safety to protect the mechanism from damage during a jam. The handwheel will be frozen, and the hook will not rotate around the bobbin.
 | 1. Cut away the knot near the needle, remove the fabric. 2. Open the bobbin housing and remove any stray thread, be sure the bobbin is not stuck. 3. Press in the safety button (1) and turn the hand wheel away from you till it clicks, and the button pops up. 4. Turn the wheel towards you. You may hear another click. Continue turning till the take-up lever is at its highest position. 5. Re-thread and continue sewing. |
Cleanup
| CLEANUP CHECKLIST 1. Power off and drain the machine 2. Unthread machine head and spool 3. Remove bobbin 4. Wipe down, vacuum, and blow out lint and stray clippings 5. Sweep up threads, lint, and debris and deposit in waste bins 5. Return checkout kit 6. Note any maintenance needs or concerns on the tag and at protohaven.org/maintenance |
MAINTENANCE REQUESTS
Update the physical Maintenance Tag at the machine
- Green can be used without issue
- Yellow can be used with caution
- Red cannot be used without hazard to either the user or the equipment
Record issues at protohaven.org/tools This notifies our staff and volunteer maintenance crew of any issues.
Troubleshooting
| Common Issues | Possible Causes | Resolutions | |
| Machine stops working after a jam—the hand wheel will not turn, or the hook does not rotate around the bobbin. | The safety mechanism has locked the hook. | Power off and drain the machine. (see Safety Reset above) Remove the jam near the needle and below, inside the bobbin housing. Reset the safety. | |
| Thread comes out of the tensioners | The thread around the check spring disk isn’t pulled up until it clicks. | Re-thread the machine with the presser foot raised to take tension off during threading. | |
| The check spring disk may be loose. | Make a maintenance request at protohaven.org/maintenance and notify the tech on duty. | ||
| Missed stitches | The needle is inserted improperly. | Be sure that the scarf is to the right | |
| The needle is threaded right to left | Re-thread left to right | ||
| The needle is bent or broken | Replace the needle | ||
| Loud noise while winding the bobbin | The presser foot is down. | Use the manual lever to pick it up. Unthread the needle, (preferable take it out) be sure nothing can roll towards the drive shaft. | |
| Thread seems stuck—can’t pull stitched fabric away from the presser foot after sewing the seam. | The tensioners are not dis-engaged | Push the knee pedal HARD to the right to dis-engage the tension. |
Special Setups
WINDING THE BOBBIN WHILE SEWING
For large projects, a second bobbin can be wound while sewing.
- A second spool of thread is required.
- The needle and presser foot remain in place
- Follow all other instructions in “Bobbin Winding” above
CHECK SPRING
The Check Spring is used to alter the amount of thread being pulled away from the thread spool above, used for very small or very large stitches or very thick material..
To adjust the stroke of the check spring, please make a Special Setup Arrangement with a Protohaven Staff Member to gain clearance in advance of use.
Additional Resources
HOW-TO GUIDES
Juki Walking foot overview:
https:%%//%%www.youtube.com/watch?v=qfXDo4xr-FU
https:%%//%%www.youtube.com/watch?v=cr2VmyJDZFk
How to thread and oil the Juki walking foot:
https:%%//%%www.youtube.com/watch?v=aaNsmgHQzTo&t=31s
https:%%//%%www.youtube.com/watch?v=Y1ZYwIwYRC0&t=2s
Sewing Gold Channel: Operating videos on many machine models, and how-to’s on sewing a range of fabrics
SUPPLIES
Wawak —Place to buy Needles and thread of every type, including heavy duty and embroidery
The Thread Exchange - thread and needles
Staff-Use
AUTHORIZED MAINTENANCE CREW ONLY
If you are part of the maintenance group please log on to the #maintenance channel of our Discord server to:
- Perform a Maintenance Action
- Request a Maintenance Purchase
- Review complete Maintenance Logs for each machine
- Generally chit-chat about maintenance
| === Hippocratic Oath === * Start with the Manual * Ask questions * Do no harm * Know your limits * Document your actions |
Lubrication
- Faceplate, manual p. 15
- Top plate, manual p. 16
- Hook, manual p. 17
- Video Part 1: https:%%//%%www.youtube.com/watch?v=cRUNec9Qrgs
- Video Part 2: https:%%//%%www.youtube.com/watch?v=onPC3g70KZM
Safety Clutch Release
- Resetting the Safety Clutch, manual p. 43
Adjusting the Check Spring
The check spring must always be taut so that it naturally bounces back. If the nut has been loosened, and the spring is not pulling back down, it must be reset.
- Adjusting the thread take-up spring, manual p. 28