How to Thread a Singer Heavy Duty Sewing Machine

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If you’re looking for how to thread a Singer heavy-duty sewing machine, I’ll teach you how with my Singer 4423 heavy-duty sewing machine as an example. 

Most Singer heavy-duty sewing machines will be threaded in an identical (or very similar) way, so you should be able to thread your own machine at the end of this tutorial. 

This threading tutorial includes step-by-step instructions with lots of pictures and even a video! 

Diagrams from user manuals are sometimes very confusing, and I always like to see real-life pictures. (If you are looking for diagrams, though, you can find them on the quick-start guide included with your machine or the online machine manual.)

Specifically, I’ll cover Singer heavy-duty bobbin threading, how to insert the bobbin, how to thread the upper thread, how to use the optional automatic needle threader, and how to raise the bobbin thread.

So, let’s get going!

(As an aside, I have another tutorial for how to thread a Singer sewing machine if you’re looking for that instead.  The process is just slightly different.)

how to thread a singer heavy duty sewing machine

Threading the Singer 4423 Video

My husband recorded a sub-par video of me threading my Singer 4423 that you can watch if you prefer video over pictures.  Sorry that he’s a bit of an overactive filmer!

YouTube video

How to Thread a Bobbin on a Singer Heavy Duty Sewing Machine

Threading the bobbin on a Singer heavy-duty sewing machine happens on the top of the machine and is identical to winding the bobbin on a regular Singer sewing machine.  There are some instructions printed on the top of the machine as reminders if you need a refresher.

First, you need to put your thread spool on the spool pin.  A horizontal spool pin will also need an appropriately-sized spool holder on the top to keep the thread from coming off once you start sewing. There are a lot of threads that will work on a Singer sewing machine.

Then, pull the thread through the first thread guide.  You’ll feel it kind of fall into place when you get it through.  Don’t pull the thread under the handle when you’re getting to this thread guide.

first thread guide on singer heavy duty

Next, wind the thread around the bobbin winder tension discs.  You need to make sure the thread goes in between the discs; you’ll feel it when it goes between.  The thread needs to be wound clockwise as you see in the diagram below.

around the bobbin tension disc wind around the bobbin tension disc

Pull the end of the thread through the small hole in the top of your Class 15 bobbin.  Place the bobbin on the bobbin spindle and push it to the right.  Here’s that little hole right before I pushed the bobbin to the right.

insert thread through bobbin hole

While still holding the end of the thread, push slowly on the foot controller to wind the thread just a few times around.  I like to take this time to stop and trim the free end of the thread that I was holding.

wind the bobbin a few times aroundNow, hands-free, go ahead and push down the foot pedal full speed to wind the bobbin until it is full.

Cut the thread and then push the bobbin spindle to the left again.  Remove it from the spindle.

how to wind a bobbin on a heavy duty sewing machine

How To Insert the Bobbin on a Singer Heavy Duty Machine

Singer heavy-duty machines (at least the newer ones) feature top-drop bobbins, which are much simpler than the front-load bobbins on standard Singer sewing machines.

Inserting the bobbin is most safely done with the sewing machine off if you’re not sure what you’re doing.

To insert the bobbin, first, remove the bobbin case cover.  There’s a small little tab on the right side that you’ll push to the right to have the cover pop open.

how to remove a singer heavy duty bobbin

Insert the bobbin where the thread is wound counterclockwise.

Right at 6 o’clock, there’s a small slit in the metal bobbin case.  Pull the thread through this slit.

how to orient bobbin

Pull the thread counterclockwise to the left in this slit until you read the small notch.  Then, pull the thread out of the notch.  If your bobbin is moving during this, hold it in place with a finger.  (In the picture below, the notch is just to the right of where the thread is going.)

bobbin case front load

Pull around 6 inches of thread out from the bobbin and pull it to the back of the plate.  Reattach the bobbin cover.

front load bobbin

Threading the Upper Thread

First, turn the handwheel towards you on the right of the machine until the needle is at its highest point right before it goes down again.  Raise the presser foot.  Raising the presser foot is VERY important in avoiding thread tension problems.

Again, it’s safest if the machine is off for this part.

The thread should still be on the spool pin, and the thread spool holder should be holding the thread in place.  Take the end of the thread and again pass it through the first thread guide like you did when threading the bobbin.

first thread guide on singer heavy duty

Pull the thread then through the pre-tension spring at the back of the machine.  You’ll pull the thread from back to front to catch it.

second thread guide on singer heavy duty sewing machine

Draw the thread down the front of the machine on the right channel.

pull thread down right channel

Make a U at the bottom and pass the thread up the left channel.

pull thread around u and up

At the top of the left channel, there’s a thread takeup lever.  Pull the thread from right to left through this lever.  If your needle isn’t in the up position, you’ll have issues finding the thread takeup lever.

go around the thread takeup lever

Pull the thread down again in the same left channel after it’s hooked on the lever.

pass thread down on the left side of the channel

Below the U on the face of the heavy-duty machine, there’s a horizontal thread guide.  The thread needs to go through this.  Pull the thread in through the opening on the side.

pull thread through metal thread guide on top of presser foot holder

At the top of the needle, there’s a thin needle clamp guide.  Pull the thread through this.  There’s also a small opening on the side to get the thread through.

loop on the metal needle clamp holder

If you don’t have an automatic needle threader, make sure to thread the eye of the needle from front to back.  If you do have a threader, keep reading below.

Using the Singer Heavy Duty Automatic Needle Threader

If your sewing machine comes with an automatic needle threader, then threading the eye of the needle will take less effort on your part.  I’m not in love with automatic needle threaders as a general rule, but I do think the Singer needle threader is better than the Brother automatic needle threader.

For the needle threader to work, the eye of the needle has to be perfectly placed just-so.  If the eye is too high or too low, the hook of the threader will not pass through the hole. You may end up just damaging the threader.

Also, you need to have the stitch dial set to straight stitch, center needle.  If your needle is off-center, the threader will also not work.

Now, to work the needle threader, pull the lever on the left of the machine down to its lowest point and rotate it towards you to where the small hook of the threader goes inside the eye of the needle.  Wind the thread around the thread guide, which looks like an upside-down metal V.  Go over and then under in a counterclockwise manner.  I’ve pulled the hook out a little to show you what the hook looks like better.

using the singer needle threader

Pull the thread against the hook that’s in the needle trying to catch it on the very small interior hook.  It helps to run the thread from the bottom to the top to catch the hook.  Here’s a very zoomed close up of the hook inside the hook.

the hook on the singer auto needle threader

Once that’s set up, release the lever by rotating it away from you and allowing it to return up to its regular position.  You’ll probably have a small loop of thread in the back, so go ahead and pull the end of the thread to the back of the needle.  Leave several inches.

singer auto needle threader

Raising the Bobbin Thread to Start Sewing

Even though you’ve finished threading your Singer heavy-duty sewing machine, you’re not ready to start sewing until you raise the bobbin thread.

To do this, hold the end of the upper thread in one hand and turn the handwheel towards you with the other hand.  This will advance the needle down and then back up.  When the needle rises back up, the bobbin thread will come with it.

raising the bobbin thread

Gently tug on the upper thread to bring the bobbin thread up through the hole.

Last, pull both threads back underneath the presser feet.

place both threads under and behind the presser foot

If your thread won’t raise, make sure it’s not trapped by anything like the bobbin case itself, the extension table, or bobbin case cover.

threading a singer heavy duty sewing machine

Conclusion – Singer Heavy Duty Machine Threaded!

Good job! You’ve learned how to thread your Singer heavy-duty sewing machine.  Thanks to the easy top-load bobbin and helpful instructions on the body of the machine, threading is a breeze once you’ve done it a few times and committed the process to muscle memory.

Now you can start sewing all your exciting projects!


  1. Hi I have the same machine. Have you ever had issues with thread bunching on the Take up Lever?


    1. Hi! No, I’ve not noticed that happening on my machine (unless I use metallic thread, which does give me issues sometimes.)

  2. Hello,
    Thank you for the great pictures. I am getting an extra thread on the bottom and I have re-set the machine top and bottom. Know what I have done wrong?

    1. Does this happen before you start sewing, or does it happen after you’ve been sewing for a while?

      Also, is it actually two thread ends coming up? If so, try trimming the thread tail shorter so it won’t catch and come up also with the free end of the bobbin thread.

      Or, if you’re pulling up the bobbin thread before you start sewing, it does look like a thread loop (so two threads, kind of.) If that’s what you’re seeing, keep pulling the bobbin thread up more, and the end of the thread will eventually come out. (Hope that last part makes sense!)

  3. Thank you!
    Your very helpful tutorial on how to thread my Singer heavy duty machine was and is of great assistance in helping me get my Singer properly
    Thanks again!
    brett d.

  4. Thank you for the tutorial. It is helpful. However I am still having trouble with the the self threading feature. I will just do it the old fashioned way and save time until I master the new technique.

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