Tip: Maybe a bargain in finding a machine / thread injector

[DemostiX]

This assumes almost no knowledge whatever, and no mechanical ability:

For those scouting old sewing machines / thread injectors, those great all metal engines probably built to run 10,000 hours or 100,000 hours of hem and seam, which ever comes first:

In looking at some previously-owned machines, and in learning to use one/several, I've found bobbin holders and hooks that have scratches in them, and the scratches have not always been repaired by sanding and polishing.

You're going to have to know how to remove a bobbin holder and the hook to clean that area, no matter what machine you operate. Learn to do that on any machine you can, and learn how smooth and polished those parts are: the bobbin holder, and the hook.

Some of those scratches have been put there by inexperienced and untrained operators, like me, who thought they could sew through obvious missed stitches and collections of thread in the bobbin area. Wrong, and with lousy consequences: The needle gets deflected, goes where it shouldn't and scratches the bobbin or hook, especially the hook right after the point.

Why that matters so much: This isn't cosmetic. Smooth passage of the thread around the hook and over the bobbin is absolutely essential for 100% complete stitch formation. Find any imperfections which MIGHT snag thread, and you may have found THE REASON why someone gave up on the machine. Not just missed stitches, but repeated bunching of thread in the bobbin / hook area. You may have on your hand a real find, all other things being equal.

In other words, with no mechanical know-how whatever, you may be able, with wet-or-dry sandpaper, 600-1000 grit and 5 minutes of patient rubbing, to remove the only reason someone gave up on the machine as much as 30-40 years ago. The difference between a machine that does not skip stitches and one that does can be like the difference between the typical magazine photo of a model, and the real thing. Cheaper than Photoshop or Gimp, and without 1% the skill to use those tools, all that may be required is some rubbing. (So there's no confusion here <smile> you don't want the REAL model. You're after the one that has had all the imperfections and blemishes removed.)

If you can get the current owner to operate the machine and produce some lines of stitches, hopefully with some skipped ones, you can look for lint in the bobbin area, and especially those scratches, all without saying exactly what you are looking for; and you may be able to strike a better deal than you hoped for, the machine needing nothing but that repair you can do yourself.....and probably a lot of patient re-oiling to dissolve old varnishes and re-lubricate those bearing surfaces.

I'll add, for further negotiation and economical shopping: Replacement hooks and bobbin cases of known top quality are as much as $15-$20 each, or more. I don't know enough to say whether gouges that have been sanded smooth can then be filled, sanded (and lacquered) for repairs that are good enough to last a few dozen (or hundred) yards of stitches.

[Ramblinrev]

you may be able, with wet-or-dry sandpaper, 600-1000 grit and 5 minutes of patient rubbing, to remove the only reason someone gave up on the machine as much as 30-40 years ago.

IMO 600-1000 grit _might_ be alright for the bobbin case but is border line for the hook. DO NOT try to do any cleaning of the insides beyond those items with sandpaper. Many of the internal parts require polishing compound to get the smoothest finish you can get. This espeically true if you are trying to get rid of rust or corrosion. It is true that a messed up hook can create no ends of stitch problems. Adding more scratches with to rough an abrasives merely compounds the problem.

Do not use 3-in-1 oil no matter what the container says it can be used for. It is not good for sewing machines.

[Troy64]

How is Kroil for sewing machines/thread injectors?

[gmcttr]

If you want to maintain/repair your own machine, get off of this forum and onto one about sewing machine care where you can get much better info along with service manuals, etc.

Demo is right that a poorly stitching machine may only require minor cleaning, adjustments or repairs to bring it back to top performance. On the other hand, it may need $35 bobbin holder, a plastic gear that is no longer available or a complete electrical re-wiring. You better have a little knowledge ahead of time if you are thinking of buying a machine that is not working well. Just my .02....you are welcome to take it or leave it.

[gmcttr]

How is Kroil for sewing machines/thread injectors?

Fine for dissolving dried up oil. Apply it sparingly and oil correctly afterwards (see the owners manual). Test in an inconspicuous area to check for damage to paint or decals.

[DemostiX]

IMO 600-1000 grit _might_ be alright for the bobbin case but is border line for the hook. DO NOT try to do any cleaning of the insides beyond those items with sandpaper. Many of the internal parts require polishing compound to get the smoothest finish you can get. This espeically true if you are trying to get rid of rust or corrosion. It is true that a messed up hook can create no ends of stitch problems. Adding more scratches with to rough an abrasives merely compounds the problem.

Do not use 3-in-1 oil no matter what the container says it can be used for. It is not good for sewing machines.

If I could find locally finer grits than the 600 and then the polishing paper another sewist furnished me, I'd have gone that route. Where there's a scratch, there also displaced metal above the surface. Polishing compound won't pare that off. Suggestions of how best to do it are welcome.

I expressly wished to limit this thread to help in finding a machine that might have that issue alone --scratches in the hook / shuttle or bobbin case. Everything else is beyond the scope of the thread. [pun].

To sum up: There can be lots of things wrong with a machine. Anything but smoothness in the mentioned areas, easily caused by user's accident or ignorance, and DIY repairable / restorable, are enough to have those who don't know better abandon a machine, especially if they are put off by a minimum $70-$90 professional service. Further, someone from a next generation who pulls out the machine, gets it to operate, but not satisfactorily and who doesn't know to look for this problem when it is there may be offering the machine for sale. That the machine might need more than is acknowledged, but off-topic.

[Ramblinrev]

To sum up: There can be lots of things wrong with a machine. Anything but smoothness in the mentioned areas, easily caused by user's accident or ignorance, and DIY repairable / restorable, are enough to have those who don't know better abandon a machine,

We are in total agreement there.

[Ramblinrev]

The reason for the oil comment was some people use oil as a base for wet sand paper. 3 in 1 would be a bad choice.

[gmcttr]

If I could find locally finer grits than the 600 ...

You might check with a local glass company or plastics supplier to see if they have it for use in polishing/repairing plastics. Crocus cloth would have some uses as well.

[Detail Man]

Rehabilitating old sewing machines is a hobby all by itself, and can be addictive. Someone gave me a circa 1927 Franklin Rotary with a White branding. She couldn't get the bobbin thread to pick up resulting in the thread jamming up. She replaced the motor, bobbin case, shuttle, and I don't know what else. After ending up fed up with the process, she gave it to me.

It all came down to a thread tension issue. After removing the head of the machine I realized the thread tension mechanism was way too tight. After some minor cleaning and getting some screws backed off, it sews like a dream.

She abandoned this machine because of a two screws being too tight. Granted one of them was accessed by partially disassembling the machine, but that's all it came down to.