Sewing machines

This page covers the maintenance of domestic sewing machines.

Summary

Older sewing machines are virtually indestructible and with simple maintenance can continue to give good service almost indefinitely. Newer machines often have plastic parts which wear out quite quickly. Nevertheless, all machines can give longer service, properly cared for.

Safety

Always unplug from the mains before staring any maintenance or repair work, in order to eliminate the risk of electric shock or physical injury from moving parts.

Sewing machine oil is highly flammable and can be ignited by overheating parts.

Older machines, particularly can weigh as much as 20kg. Take care when lifting or when tipping over to service the under side.

Warning

On no account use anything but sewing machine oil to lubricate the mechanism. Do not use WD40, or 3-in-1, or bicycle oil, or engine oil, or grease, or olive oil, or Vaseline, or snake oil, or peanut butter. None of these are sewing machine friendly.

Spare parts

Spare parts for modern machines may be available directly from the manufacturer or a distributor. For older machines, eBay is always a good place to look. Helen Howes in Norfolk holds a wide range of parts.

Bobbins and needles are available at any good haberdashers. Spare and alternative feet are commonly available (check the height of the fixing screw from the base of the machine) and replacement belts shouldn't be a problem, nor replacement rubber tyres for bobbin winders. Complete bobbin winders are available for classic Singer machines using a bullet-type shuttle, but for others there are many different designs and you may have more trouble.

Acknowledgements

This wiki pages is based on a Restart Skillshare session led by Jennie of Cheeky Handmades with assistance from traid.

Sewing Machine Principles

Regular users of a sewing machine will be familiar with its operation and can skip this section, which is provided for occasional users or those simply faced with a non-working machine.

Sewing Machine Controls

The accompanying pictures show a sewing machine probably dating from the 1950's. This has the advantage for demonstration purposes of having all the basic controls easily seen.

Sewing machine controls 1/4.

At the business end of the sewing machine, the foot presses down on the work, enabling the feed dogs below to feed it through the machine by a kind of walking motion. Alternative feet may be provided for different jobs. They are secured to the vertical shaft with a knurled knob.

Sewing machine controls 2/4.

A screw or knob clamps the needle to its shaft. Needles normally have a flat side which clamps against the flat of the shaft.

An adjustment on the top allows the pressure of the foot on the work to be adjusted.

The top thread passes through an adjustable tensioner, allowing the tension of the top thread to be equalised with that of the bottom thread. When properly adjusted, the threads should engage with one another within the fabric. Badly adjusted, the top thread will lie on top of the fabric or the bottom thread on the bottom, with the other thread passing through the fabric and back again.

Sewing machine controls 3/4.

Behind the head of the machine a lever allows the foot to be raised in order to insert or withdraw the work, and lowered in order to sew. This is normally operated blind by feel.

The hand wheel on the right is driven by a belt from the motor. You can turn it by hand to stitch one stitch at a time, or to ensure the needle is disengaged before inserting or removing the work.

A bobbin winder (missing on this particular machine) engages with the hand wheel in order to load bobbins with thread. A knurled knob on the hand wheel allows it to be disengaged from the sewing machine mechanism whilst winding bobbins.

Sewing machine controls 4/4.

The stitch length adjuster varies the distance the work is moved between stitches. The reversing button (or lever) allows you to sew in the reverse direction. (You should always do a couple of reverse stitches at the start and end of a line of stitching to lock the ends.)

The zigzag width control allows alternate stitches to be offset sideways to produce zigzag stitching. More modern machines often have a plethora of stitching styles controlled in a similar way.

The feed dog height adjustment allows the feed dogs to optimally grip fabrics of different types.

Common problems and solutions

Machine seized up

After many years of disuse a machine may completely seize up. Lubricate thoroughly as described under Maintenance. You may have to leave the oil for a while in order to ease the parts and repeat several times, wiping away any excess.

Snagging or breaking thread

First of all, if you have disassembled anything, make sure you have reassembled it correctly and that you can turn the hand wheel freely. Ensure the needle isn't bent and that it feels smooth as you run it between your fingers from the shank to the tip.

Make sure the machine is threaded correctly. If you don't have a printed instruction booklet, look on the Internet for instructions for the same or a similar model. On some machines you thread the needle from left to right, and from right to left on others. It's important to get it right.

Ensure the bobbin is threaded and fitted correctly. The bobbin case holder has a sharp point which catches the top thread. Problems can result if this has been roughened by needle strikes. Smooth it with fine emery as described under Maintenance.

Before starting to sew, make sure there isn't excessive slack in the top thread. If you have just fitted the bobbin, place your finger on the loose end of the top thread and turn the hand wheel as if to make one stitch. When you now pull the top thread it should draw up the bottom thread. Place your finger on the loose ends of both threads as you make the first stitch or two otherwise they may snag.

Poor speed control

If nothing happens when you press the foot pedal a little, but the machine races when you press it just a little more then it will be very hard to sew successfully. The foot pedal may simply need lubricating. On older machines this will contain a rheostat, which is a variable resistance wired in series with the motor. Newer machines will more likely have an electronic speed control similar to a dimmer switch.

First, double check that it's not still plugged in. You will need to examine it to determine how to disassemble it. Do not use sewing machine oil, but rather any light lubricating oil, or grease on sliding parts, and keep oil and grease away from all electrical contacts.

Also, check the belt tension. Check out the page on Electric motors if the motor may be faulty. Replacing the brushes or cleaning the commutator might be necessary. The motor bearings can be lubricated with light lubricating oil.

Maintenance

Top mechanism.

The first thing to do (before disassembly) is to remove all dust and fluff. Between the feed dogs is a favourite place for it to collect. Where it has become matted you can pick it out with a pin or a needle, otherwise use a brush, a can of compressed air or a vacuum cleaner crevice tool.

Bottom mechanism.

A well used machine may need lubrication and cleaning several times a year. Once a year is beneficial even for light or occasional use. Older machines allow easy access to the mechanism. Newer machines tend to be completely enclosed in plastic. There may be screws holding the case together but even after removing these it may be tricky to open. If the case is in two halves, probe the crack between them. You will probably find a series of clips that can be released with a thin spatula or knife, or a prying tool, or it may become evident that there remain one or more screws to remove.

Next, oil anything that moves. Remember, use nothing but sewing machine oil. There will be various levers, cams, cogs and bearings both in the top of the machine driving the needle, and under the base driving the bobbin and feed dogs. Wipe away any excess oil, and avoid getting it anywhere where it could contaminate the next sewing job.

Remove the bobbin and bobbin case, and any dust or fluff on them. The bobbin case fits into a bobbin case holder which rotates as the machine operates. It should be easily removed, for example by releasing a pair of clips. It has a sharp point which catches the upper thread in order to engage it with the lower thread. Run your finger over this and if it feels rough (probably due to needle strikes) then smooth it with fine emery. Take care to reassemble it correctly.

Removing the bobbin case.

Bobbin case removal (machine on its side).

Bobbin case holder retainer.

Bobbin case holder in place.

Bobbin case holder removed for inspection.

Note that some older (especially pre-war) machines have a quite different design of bobbin. This fits in a bullet-shaped shuttle which is thrown through a loop in the upper thread to make each stitch.

Check for any roughness on the needle, possibly caused by it striking something. It can be smoothed with fine emery but is probably better replaced.

Bobbin spring and tension screw.

Checking the bobbin tension.

Finally, check the bobbin tension. Fit a bobbin of thread to the bobbin case and thread it under the tension spring. Suspend it by the thread. The tension is correct if the tension is just sufficient to support the weight of the bobbin and case. Adjust the tension by adjusting the screw in the tension spring.