Sewing Machine Maintenance

Winter is coming, time for making gear in earnest for many of us, so I thought I would post a full maintenance tutorial on my machine. I hope this helps someone who has been reluctant to perform their own maintenance.

First, a Primer.
If small parts or complicated systems make you crazy this may not be a task for you.
If you are a consummate DIYer and can generally put things back together once you have them apart; then is is definitely up your alley.
There are no secrets; sewing machines are generally well engineered for maintenance and are easily accessed to the point where full maintenance can be performed. However, further teardown can result in hours of frustration and eventual self destruction; be warned.

Tools: Screwdrivers in as many flavors as you may need; generally the only two are phillips and slotted but you may need torx, star or others. Our goal is to remove the dust covers for maintenance, not take apart any of the mechanisms inside which usually require the specialized drivers.
Canned air: Not compressed air (which is usually very wet)
Grease: White Lithium works well, but any good grease will do. I use white wheel bearing grease.
Solvent: I like Hoppes No.9 for cleaning; it has the added benefit of making my sewing machine smell like my firearms. If your machine has plastic parts, and most do, make sure the solvent you use will not damage them.
Machine oil: Again, I like the Hoppes machine oil, but 3 in 1 or any other good lubricating machine oil will work.
Small brush: A good brass brush works well, but so does a repurposed toothbrush if it has pretty stiff bristles.
Patches or cotton swabs: A good wash rag will work and the cotton swabs work to get into tight spots; just be careful not to leave bits of the swab tip in the mechanisms.
Steel Wool: For polishing the shuttle hook.
Picks: You can use a seam ripper, small awls or the like; just be aware that a very sharp point could gouge or damage plastic parts.
Light: A good light is mandatory, I use my headlamp.
Pliers: Small needle nose may be all you need, but a good set of hemostats could also come in handy.
Time: Two hours or more for the first time, less for subsequent tasks.
Work space: Clean, level, comfortable.
Digital camera: Snap a shot before you disassemble something as a reference for reassembly.
Owner's manual: If you have one it is a great resource for oiling points and other information.

I am opening up my Kenmore machine (her name is Rosie); I have owned this machine for four years but she is considerably older than that (early 70's). I am the second owner of this machine and I should have done this when I bought her; it has been four years and she is a little rough now.
A few reasons why:
I noticed a distinct 'clacking' that wasn't there before.
I had also noticed she was a little jumpy at slower speeds and tended to need more power/RPMs than I thought for detail work.
Lastly, she would sometimes fray the top thread especially when using heavier weight thread.

Notice that timing, binding or balance are not any of the things I am having trouble with. If I suspected any of these I would have taken her to a repair shop or, if I had found these to be the cause after I opened her up I would have taken her in.

Okay, getting inside!
Most modern machines (yes early 70's is modern) only require a one side tear down. What this means is you only need to remove one side of the machine to gain access to the internal mechanisms. This allows us to perform routine maintenance without needing to take apart anything that would need to be retimed when we reassemble.

Take your time and find all the screws; they will be accessible but may be hidden behind aesthetic plugs or may only be accessible after the knobs have been removed. DO NOT try to force anything apart!
Unplug the machine, remove the knobs/sliders; generally you do not need to remove the pully.

Once all the dust covers have been removed you will have full access to the mechanisms. The major parts are:
The head
The upper arm
The motor and/or pully
The lower arm
The bobbin/shuttle
Again, there is no need to take any of this apart, we are just going to clean and lube.

I found what was causing the binding in my girl; you can see in this image that the needle bar bearing had a pretty good wad of thread wrapped around it. It was easy enough to remove the C-clip on the upper shaft, remove the connecting rod, clear the thread, lube and reinstall.
A word here: When you remove a component like this only do one at a time! It is easy to get parts confused and reassembled in the wrong place, take pictures for reference.



The original grease had become very hard so I removed this as well and added new grease.

I also added grease to the main drive gear after giving it alight cleaning. Oil and grease go a long way, no need to over do it. Add about the same amount as what was there originally. If you put too much it will be slung off into parts where it may cause trouble; this is especially true around the shuttle/bobbin area where excess grease will foul the thread.



It's a good idea to snap a few images of the belt(s) model number as well (or write them down).





You can see the needle bar, presser foot bar and offset are in pretty good shape; just a light clean and drop of oil is all that was required.



The shuttle hook was causing the problems with frayed thread; it had a small burr and was in need of polishing. I used 00 steel wool to remove the burr and polish the hook to a nice finish. No need to break out the dremel, a little oil and steel wool will do the job!





The shuttle race was disassembled cleaned and checked for burrs and nicks; none found.



The shuttle drive was cleaned and greased.



The bobbin stop, which guides the thread carrier, was also removed, cleaned and greased. The small rectangles in this are actually greases wells, I filled them with white grease, cleaned the thread carrier and reassembled.



Thread carrier.



The shuttle drive is attached to the lower arm; there may be several cams in this area that drive multiple components (feed dog etc). Carefully remove any residue that may be present (metal powder, plastic duct etc) and the old grease prior to adding the new grease.



Along the way remember this: Don't attempt to move components by way of pushing or pulling; it is much better to spin the pulley to get things to move where you need them.

Reinstall the dust covers and give her a good long trial; slow, fast, zig-zag etc. Make sure the thread tension is correct; sometimes the thread tensioner gets bound when reinstalling the cover (if it is on the cover). If you are sucking the top thread all the way under the stitch with the bobbin thread flat, you probably have an upper tension problem. Don't attempt to adjust the bobbin tension, find out why the upper thread tension isn't working; especially if it was working before the tear down!

Congratulations, your machine is ready for another five years of hard work!