Singer 513 "Stylist" sewing machine

I/ve no idea of the torques involved but assuming low enough you can take a "plug" off a good part of the original gear, then a mould negative, fit over the broken section and a couple of small pins and epoxy to cast a new section, then fettle

Have you considered the likelihood that the helical gears are a better solution for your machine, less likely to have teeth break off and damage needles? The straight gears were cheaper to make, perhaps, but the cost of replacement parts can justify new tooling. Perhaps the helical gears make it easier to time, as well.

Rather than try to find some Singer dealers who hang on to their NOS forever, why not just buy the new pair and mount them? The important thing when a piece of well used and loved equipment breaks down, is to get it back working ASAP.

While I would agree with you that helical gears in general are a better design, I don't think that they would be easier to time. That part of the job would be a wash. But disturbing the other gear that meshes with this one creates a second timing problem along with a great deal more work as well. If this was a customer repair I would not want to be married to this thing and so I would not do it this way. If the other gear should ever fail in the future then we'll break another needle and I'll have to get into this anyway so for the time being that's why I figured on just doing the one gear. Lenny

For timing, note how many degrees the handwheel turns between the needle starting to go back up and when the hook on the bobbin goes past the needle to catch the thread. If the timing is already shot, then take a look at another similar sewing machine. On my wife's machine, the needle has just started to go back up when the pointy end of the bobbin holder goes past and snags the thread that is sticking out the side of the neeedle.

(...)

Mr Kedidelhopper ruined my afternoon with an email requesting my input on this. Unfortunately, I'm interested as I'm slooooooowly drifting into the sewing machine repair biz (since computer repair sucks right now). At this time, I'm into the Learn by Destroying mode.

I found this video showing how to replace the hook drive gears and how to adjust the timing.

If you watch the video, it's fairly straight forward, but not simple. Due to the complexity of disassembly, maintaining the timing is not going to happen. In addition, both meshing gears should be replaced as the existing "good" gear is almost certainly worn and will be a poor fit for the new gear.

When I work on such an older machine, I often find more parts that could use replacement. There are other pairs of gears in the 513 that might be worth replacing as preventive maintenance. The parts are cheap, but the time to tear it apart is not.

Reminder: Use a digital camera to take photos BEFORE you tear it apart, so that you have a fair chance at putting it back together. I also make an 8.5x11 print of the guts and place it on a sheet of styrofoam. As I remove parts and screws, I push them through the print and into the styrofoam, so that I know exactly where the fit.

Unfortunately methinks there's a problem with the video. The author ends the video by plastering copious quantities of grease onto the plastic gears. In my never humble opinion, this is a bad idea. Many plastic gears will be attacked by the solvents in the grease and crumble. In particular, nylon gears are easily eaten by grease.

Here's an article that largely substantiates my pontifications:

Gears, on the other hand, require grease. Of course, not just any kind of grease, but sewing machine grease. Singer offers a very good light grease available in a small squeeze tube called (what else?) Singer Lubricant. I highly recommend it. But only for steel gears. Plastic gears do not, and should not, require lubrication. Translation: Don't grease the plastic gears, just the metal to metal gears.

Clarification time. There are several plastic safe greases available. White lithium grease and white grease with Teflon are both safe. Silicon grease, molybdenum disulfide and many synthetic greases are also safe. Soap will also work. What isn't plastic safe are greases loaded with petroleum solvents, such as axle grease, engine oil, etc.

Incidentally, the official HP policy for their printers is to NOT use any lubricants:

That is the critical point (no pun!): As the needle starts to rise it throws out a tiny loop of slack thread which the bobbin hook is supposed to catch. If the hook goes past before the needle has risen, the thread will still be tight against the side of the needle and the hook will miss it.

I think I see what you guys are talking about. I can compare another working machine I have here to this. It is also a Singer but slightly different. The bobbin assembly mounts on end rather than lying flat but it seems like catching the bobbin thread should still work the same way. Thanks a bunch. Lenny

It is the upper thread which is caught and pulled around the bobbin, not the bobbin thread.

The principle is common to most lockstich machines, sometimes the bobbin case is in the form of a long shuttle, which plunges bodily through the thread loop of the needle. Sometimes the bobbin stays still in the centre of a ring; the ring rotates or oscillates and a notch in the outer edge acts as a hook to catch the needle thread and pull it around the bobbin holder.

As you say, the rotating or oscillating hook ring and the bobbin can be in the vertical or the horizontal plane, but the timing is the same. Some layouts are easier for the manufacturer to make, some are easier to drive and others are easier for the operator to thread-up or clean. (I'm sure some of the more bizarre arrangments are just a way of getting around a patent.) A continously-rotating ring causes less vibration than an oscillating one, so that tends to be used on higher-speed machines.

Good luck with the repair.

Some of these videos on how it works might help:

Careful. Some of these videos are really awful.

This isn't a 513, but shows how it should work when properly adjusted: