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Rotary Hook Inspection and Adjustment Procedures for EMT16Plus and EMT16*

Introduction
*These instructions are for the EMT16 Plus and EMT16 machines purchased in mid-2017 or later (Machine Serial Numbers 403291 and above) which feature the latest style of mainboard. This can also be used for earlier EMT16 machines which have had a mainboard upgrade.

The 6 hook adjustments cover:
1. Needle Case Calibration (Needle Centering)
2. Needle Depth
3. Hook Timing
4. Needle-to-Hook Gap
5. Rotary Hook Support (Retaining Finger) Adjustment
6. Completion: Reassembling Hook Covers and Needle Plate Centering

This entire procedure can take from :30 to :90 minutes depending upon how many of these corrections are necessary.

These steps should all be performed in order; as the later adjustments are dependent upon the accuracy of the earlier steps.

-Needle Case Calibration (Needle Centering) & Needle Depth are needle specific and should be checked for all needles.
-Hook Timing & Needle-To-Hook Gap are set to specification on the Closest Needle (see Adjustment #3 below)
-Rotary Hook Support & Needle Plate Centering are not needle specific and can be done with any needle.


Preparation: Disassembling Hook Covers

1) Make sure that the Melco OS program is running on your computer and your Melco embroidery machine is powered ON.

2) Close any menus and click the Reset Design icon.  mceclip0.png


3) Remove the hoop and hoop arms.

4) Remove the Bobbin Case (1st image below), Needle Plate (2nd and 3rd images) and Hook Guard (4th and 5th images). Do Not Remove the Rotary Hook Support (aka. Retaining Finger) (6th image).

mceclip1.png   mceclip6.png     mceclip7.png    mceclip3.png   mceclip4.png   mceclip5.png

 

5) In Melco OS, click on Tools > Maintenance as shown below.

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6) Click on the Head Timing tab.

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7) Disassemble Hook Covers is now Completed.

 


ADJUSTMENT #1: Needle Case Calibration (Needle Centering)

1) Hold down the Needle Case button + Left Arrow to color change to needle position 1.

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2) Lower the needle to the Bottom Center position by holding down the Adjust Button and the Down Arrow.

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or...you can use the Frame Back button to bring the needle down on the next needle in the bottom center sequence.

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3) Check to see where the needle is, in relation to the rotary hook center post. Micro-step the needle to be directly above the center of the post using the Trace Button and the Left or Right Arrows.  Do NOT center the needle on the B at the back of the bobbin basket, instead check based on the center post that the bobbin snaps into.

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4) Continue micro-stepping until the needle is centered exactly to the middle of the post. Then you can bring the needle up and move to the next needle by pressing the Needle Case button + Right Arrow.

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5) Repeat Steps 2 through 5 until all 16 needles are centered. Centering must be performed on every needle.


6) After all 16 needles are centered click on the Calibration tab and the Get Table button.

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7) Click OK on the confirmation message.

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8) Needle Case Calibration is now Completed.

 

ADJUSTMENT #2: Setting Needle Depth

1) Click on the Head Timing tab.

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2) Move the current needle to needle position 16 by holding down the Needle Case button + Right Arrow and move the needle case to needle position 16.

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3) Lower the needle to the Bottom Center position by holding down the Adjust button and the Down Arrow.

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4) Look into the Hook Assembly and check the location of the needle eye compared to the picture below. Half of the needle eye should be visible in the hook assembly. If the needle’s eye is in the acceptable range, skip to step 11 in this section.

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This is Correct Needle Depth

 

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Here are examples of needles that are (1) too shallow, (2) too deep, and (3) using another needle to compare depth.

 

5) Replace the needle and check needle depth again (Step 4). If it's correct skip to Step 11.

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6) Remove the front magnetic cover.

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7) To adjust the needle depth, loosen the set screw on the needle bar drive stud and move the needle bar up or down until needle depth is correct.

mceclip25.png  mceclip26.png  mceclip0.png
Note: For needle #1 & 2 check the right side of the case for a hole that will allow you to reach the screw on the drive stud.

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For all other needles use the 2.5mm Allen Wrench with the shortened tail, which can be found in the Operator’s Kit with the machine. (not the set of 7 wrenches in the red plastic case, but the set of 3 individual wrenches packaged separately)

 

8) Verify the Needle Clamp is turned at a 45° angle to the right.

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9) Tighten the drive stud set screw and remove the wrench from the set screw.

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10) Bring the needle up and back down again with the Adjust button + Up Arrow and then Adjust button + Down Arrow. Check that the needle is at the proper needle depth position. If it is not, Repeat steps 7 through 9 above.

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11) Bring the needle up and move to the next needle by holding down the Needle Case button + Left Arrow.

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12) Lower the needle to the Bottom Center position by holding down the Adjust button and the Down Arrow.

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13) Repeat Steps 4 through 11 in this section until all 16 needles are at the correct depth. Depth is independent and must be done for each needle.

14) Bring the needle up with the Adjust button and Up Arrow.

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15) Confirm that the Needle Orientation is still 5º to the Right for any needle bars where the drive stud was loosened.

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16) Needle Depth is now Completed.

 

 

ADJUSTMENT #3: Hook Timing

1) Find the Closest Needle number. The number of the closest needle is noted in the housing.

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If you don’t see it written there, it is instead written in the bottom right corner of the main PCB tray. Remove the 4 screws that hold the main PCB cover in place (see images below)

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Remove the PCB cover. Note the C number, the Closest Needle.

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Replace the board cover and reinstall the securing screws.

2) Use the Needle Case and Left or Right Arrow buttons to move the needle case to the closest needle noted in the machine casting.

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3) Replace the needle.

4) Bring the needle down to the hook timing position by clicking the Hook Timing button.

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5) Inspect the hook timing by standing directly in front of the machine, and check that the Hook Point is even with the left side of the needle.

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This is the Hook Point.

 

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An example of correct hook timing.

 

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On the left is a picture of the hook too far counterclockwise. On the right is a picture of the hook too far clockwise.

6) If the Hook Point is even with the left side of the needle, Hook Timing is Completed...skip the rest of the steps in this section.

7) Loosen (do not remove) the two (2) timing set screws (highlighted in blue in the image below).

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You can use the Adjust button + Left Arrow and the Adjust button + Right Arrow to rotate the hook position if you don't have access to both of the timing set screws:

mceclip0.png

If you rotated the hook, bring the needle down to the hook timing position by clicking the Hook Timing button in your software.

 

8) Spin the Hook Point so it’s even with the left side of the needle. Lightly tighten each of the two (2) timing set screws before fully tightening them while applying finger pressure pushing the bobbin post in.

9) Verify the timing is correct.

10) Bring the needle up with the Adjust button and Up Arrow.

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11) Hook Timing is now Completed.

 

 

ADJUSTMENT #4: Needle to Hook Gap

If not already there, use the machine keypad to move the needle case to the closest needle noted in the machine casting (see Step 3.2 above)

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1) Bring the needle down to the hook timing position by clicking the Hook Timing button.

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2) Inspect the gap between the Hook Point and the needle.

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In the left picture the gap is correct. In the middle picture the gap is too small. In the right picture the gap is too big.

3) Try to floss a piece of 40 weight thread between the needle and the hook point. If the thread snags and catches, the needle to hook gap is most likely too small and needs to be widened.

mceclip27.png   mceclip28.png

 

4) Twist four 40 weight threads around each other to create one thicker thread, and floss that between the needle and the hook point. If the thread does not snag or catch, the needle to hook gap is most likely too large and needs to be tightened.

5) The gap between the needle and the hook point should be 0.1mm (.004”) which is between 1 and 3 thread widths. If the gap is correct, the Needle to Hook Gap is Completed...skip the rest of the steps in this section.

6) Loosen (but Do Not Remove!) the three (3) hook fastening screws (highlighted in red in the image below). If you don’t have access to the screws, use the Adjust button + Left Arrow and the Adjust button + Right Arrow to rotate the hook position. Loosen the remaining screws.

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If you rotated the hook, bring the needle down to the hook timing position by clicking the Hook Timing button in your software.

 

7) Adjust the hook to needle gap by using the 1.5mm Allen wrench with a shortened tail (the adjustment set screw is highlighted in green in the image below). Apply finger pressure pushing the bobbin post in. Rotating the set screw clockwise will increases the gap. Rotating the set screw counter-clockwise decreases the gap. Adjust until the gap between the needle and Hook Point is 0.1mm or 1-3 thread widths.

mceclip31.png   mceclip32.pngmceclip8.png

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8) Verify the gap is correct and then tighten the three hook fastening screws (highlighted in red) while applying finger pressure pushing the bobbin post in.

9) Bring the needle up with the Adjust button and Up Arrow.

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10) Needle to Hook Gap is now Completed.

 

 

ADJUSTMENT #5: Rotary Hook Support (Retaining Finger) Adjustment

1) Insert the Hook Retaining Finger Gauge between the Rotary Hook Support (Retaining Finger) and the Hook Basket. If the gauge does not slide in easily, do not force it. Forcing it may scratch the highly polished surface of the Rotary Hook Support or Hook Basket, which could damage the hook and result in excessive thread breaks.

 

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The left picture is the Hook Retaining Finger Gauge. The right picture shows where to place that gauge in the front of the hook.


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The left picture is the Rotary Hook Support. The right picture is the Hook Basket.

 

2) The Hook Retaining Finger Gauge should slide between the Rotary Hook Support and the Hook Basket with no resistance.

3) The tip of the Rotary Hook Support should be flush with the top of the Hook Basket.

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4) If Steps 2 and 3 are correct skip the rest of the steps in this section.  If they are not correct, proceed to Step 5.

5) Use the 2mm Allen wrench to loosen the 2 screws holding the Rotary Hook Support.

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6) Position the Rotary Hook Support in the notch at the top of the Hook Basket.

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7) Insert the gauge between the Rotary Hook Support and Hook Basket and set the correct placement of the Rotary Hook Support. Review Steps 3 and 4 in this section for the correct placement.

8) Tighten the 2 screws holding the Rotary Hook Support.

9) After tightening the screws, verify Steps 3 and 4 again.

10) Rotary Hook Support Adjustment is now Completed.

 

#6: Completion: Reassembling Hook Covers and Needle Plate Centering

1) In the Melco OS, got to Tools > Maintenance as shown below.

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2) Click on the Head Timing tab.

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3) Bring the needle to head up by holding down the Adjust button and the Up Arrow.

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4) Attach the Hook Guard.

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5) Attach the Needle Plate, but do not tighten the screws fully.

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6) Lower the needle to the Bottom Center position by holding down the Adjust button and the Down Arrow.

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7) Wiggle the needle plate left and right until the needle is in the middle of the hole. Tighten the screws for the needle plate. Verify the needle is centered in the hole as you tighten the screws.

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The image on the left shows correct needle plate centering.  The right image shows incorrect centering.


8) Bring the needle to head up by holding down the Adjust button and the Up Arrow.

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 9) Reinsert the Bobbin Case.

10) Reassembling the Hook Covers and Needle Plate Centering is now Completed.

 

Verification Photos:

To verify hook adjustments check the following pictures:

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