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Consumer Sewing Machine Shop Tech Guide
This document is intended for Protohaven shop techs, who need both basic clearance information as well as troubleshooting and maintenance. It starts with common problems – so if someone comes to you on shift with a question you know where to start – then goes over usage, less-common troubleshooting, maintenance, and safety.
Common Consumer Sewing Machine Needs
Supplies
- Needles & Thread - Match needle & thread size to fabric weight. Buy standard consumer needles in sizes from 65/9 to 110/18.
- 70/10, 80/12 - Lightweight fabric (gauze, chiffon, voile: sheer, floaty)
- 90/14, 100/16 - Midweight fabric (shirting, quilting cotton, flannel, twill: all-purpose fabrics)
- 110/18 - Heavier fabric (canvas, denim, corduroy: sturdy bottomweight fabrics)
- Heavy fabric (upholstery, heavy canvas) - consider a Juki instead
- Presser Feet - any consumer, low-shank presser foot will work
- Bobbins - Singer Class 15 (for sale in Protohaven shop)
How to Thread
- Raise the presser foot.
This is commonly forgotten. - Raise the needle.
Turn the hand wheel toward you until the thread lifter arm is in its topmost position. - Place a spool on the spool pin.
The thread should come towards you from the top. - Secure the spool with a spool cap.
Small, white, located in sewing checkout kit at front desk. - Follow the numbered guides.
See start guide for detailed threading diagram.
Thread tangle on bottom of fabric
Thread nests on the bottom signal a problem with the top thread. Re-thread machine, make sure the presser foot is up, make sure the spool cap is in place and thread feeds smoothly from the spool.
Some spools of thread have a notch in the endcap to secure the thread; if the notched end faces left during machine sewing the thread can get caught. If both ends are notched, try covering the notch with painters tape. Normally the spool cap comes in multiple sizes and a larger size would cover the notch and prevent the thread from catching, but we only have the tiny size.
Thread tangle on top of fabric
Thread nests on the top signal a problem with the bobbin thread. Remove bobbin and re-insert, being sure thread feeds smoothly off the bobbin forming the letter “p”.
Extreme tangles can signal a problem with the bobbin tension, but this is super rare and worth submitting a maintenance report instead of trying to fix.
Stitch doesn't look right
Always test stitches on two layers of fabric.
- Bobbin thread shows too much on top: loosen top tension
- Top thread shows too much on bottom: tighten top tension
- Other problems: post a picture to Discord
Broken needle
Broken needles happen for a wide range of reasons. Try in this order:
- Replace the needle.
- Use the hand wheel to go through several stitches slowly. If the needle hits the presser foot, change your needle position settings or switch to a presser foot designed for the selected stitch. Repeat until you can complete two full cycles of the selected stitch using the hand wheel without hitting anything.
- Continue sewing. If no further breakage occurs, the other needle was just old. It happens.
- If the needle breaks again, replace it, and switch to using the hand wheel on bulky areas. This will give you a feel for whether the needle will go through your work at all. If it is too difficult for you to push the needle through with the hand wheel, do not try to sew this seam on the consumer sewing machines. There are many possible ways forward from here; try asking on Discord.
- If the needle isn't hitting the presser foot, the hand wheel gives you no trouble on any of the bulky areas, but the needle still breaks when you use the foot pedal, this suggests a more serious problem with the machine (a timing problem or something broken or mangled below the needle plate). Submit a maintenance report and switch to a different machine.
Usage Quick Reference
Setup
Check:
- Bobbin thread
- Needle
- Top thread
Raise presser foot and thread needle.
Sewing
Check selected stitch style, stitch length, and needle position.
For each seam:
- Raise presser foot.
- Position fabric under needle.
- Lower presser foot.
- Hang onto the end of the top thread.
- Use hand wheel to lower needle into the fabric.
Adjust fabric position more precisely if needed. - Depress the foot pedal to begin sewing.
- Use right hand to pinch fabric layers together and ensure both layers feed evenly.
- Use left hand to steer.
- Use gentle tension. Pulling or pushing too hard can cause the needle to break (recoverable error) or punch a hole in part of the machine (critical error).
- Slow down when sewing over bulky areas. If the machine struggles, release the foot pedal and use the hand wheel to proceed one stitch at a time.
- Release the foot pedal to stop sewing.
Cleanup
Check, retrieve personal property, restore communal property:
- Top thread
- Needle
Machine should be put away with no needle or size 12, 14, or 16 universal needle installed. - Presser foot
Machine should be put away with zigzag foot J installed. - Bobbin
Restore to checkout kit:
- Spool cap
- Snips
- Odd presser feet
Collect thread and fabric scraps from tables and floor and place in trash.
Troubleshooting
Maintenance
Annually, the consumer sewing machines should be opened up, cleaned of lint (use a vacuum not a can of air), and oiled. We can either send them out to be serviced (Thornton is reliable) or train techs to do it. This would probably need its own dedicated techs session.
If we do the annual servicing ourselves, then every ~5 years, the consumer sewing machines should have their timing checked and adjusted. I've never done this on a machine newer than 1950, so I'd recommend professionals – especially since botched timing can lead to broken needles, damage, and injury.
Safety
Interventions
Techs should intervene if they observe any of the following while members are using the consumer sewing machine:
- Long hair that is not tied back.
The hand wheel spins very quickly, and can grab hold of loose hair. - A loud thunk with each stitch.
This means the needle is not piercing the fabric effectively, and can lead to a broken needle. Broken needles can cause eye injury. Likely culprits are too many layers or the wrong needle type (a ballpoint needle on a tightly woven heavy fabric would do it). - The sound of “an electric motor has turned on but is not moving” especially if followed by confused human sounds, and repeated instances with no stitch sounds in between.
The needle may be stuck in the down position, and further attempts can burn out the motor. Likely culprits are thread jams, too many layers, and fabric getting sucked into the machine. - Sewing over pins.
Tons of people do this; tons of people learned to do this from non-PH instructors. It's a bad idea, since when the needle hits a pin, it will bend (and may then puncture a hole in the machine) or break (and hit someone in the eye).
Normal Risks
- Sewing through a finger.
Raise needle and presser foot, remove finger from machine, clip threads if attached, and apply first aid. The needle will probably have broken; make sure you locate all the bits so nobody steps on it. Consider sending the member to urgent care, since puncture wounds can be at higher risk of infection.