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15-91 Question

S

Shot thru

Member
Joined
Jan 7, 2019
Messages
89
I have a 15-91 that runs very well. More often than I would like, when I push the pedal the motor hums but nothing moves. I have to start the wheel rotating by hand and then it sews just fine. This happens on thin material as well as several layers of webbing. Other times it starts to sew immediately when I push the pedal. Is this common with the 15-91 or do I have an issue. I rewired everything so there are no shorts or loose wires.
 
I’m not a sewing repair tech or anything but it Sounds like a clutch issue. What year is it
 
Shot thru said:
I have a 15-91 that runs very well. More often than I would like, when I push the pedal the motor hums but nothing moves. I have to start the wheel rotating by hand and then it sews just fine. This happens on thin material as well as several layers of webbing. Other times it starts to sew immediately when I push the pedal. Is this common with the 15-91 or do I have an issue. I rewired everything so there are no shorts or loose wires.
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Is it belt driven? Is the belt too tight? Is the motor and gear properly lubricated? It sounds like the motor is getting juice but not producing enough torque at start to over come the resistance being applied to it. When the times it starts to sew immediately, is the thread take up in the low or high position? Something is causing too much resistance for the motor to start its rotation and you help it when you turn it by hand.
 
I have a belt driven 15-90 clone that does the same thing. Making sure it is lubed up is never a bad idea.
Mine also has issues spooling up the bobbin, the little finger holds the bobbin too tight for it to spin so I have to "assist" by lightly lifting up on the finger.
 
15-91 is direct drive, there is no clutch. I have taken the drive system apart and lubricated the as per the repair manual and several videos. Machine was built in 1949. I happens mostly when the needle is buried but sometimes on the down stroke.
 
Shot thru said:
I have a 15-91 that runs very well. More often than I would like, when I push the pedal the motor hums but nothing moves. I have to start the wheel rotating by hand and then it sews just fine. This happens on thin material as well as several layers of webbing. Other times it starts to sew immediately when I push the pedal. Is this common with the 15-91 or do I have an issue. I rewired everything so there are no shorts or loose wires.
Click to expand...
That is very common on domestic sewing machines. It is probably a safety feature to prevent new sewers from sewing through their fingers. On industrial machines, you can easily sew through a finger.
 
Shot thru said:
15-91 is direct drive, there is no clutch. I have taken the drive system apart and lubricated the as per the repair manual and several videos. Machine was built in 1949. I happens mostly when the needle is buried but sometimes on the down stroke.
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So you probably have a grease cup of on the motor, is the motor lubed as well? Something is causing too much friction
 
Shot thru said:
Both grease wicks replaced and both bearings greased.
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If everything is lined up on the gears and the motor is greased, then you have now exceeded my knowledge or suggestions. It might be time to google sewing machine repair technician near me.
 
Shot thru said:
Thanks for your help. It has done this since I got it and none of the maintenance has helped so far. It is still a very usable machine.
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You could try to change the motor out for a servo. Maybe it just needs a little more starting torque
 
This motor is integrated into the gear box so I don't see how it could be swapped out. I am thinking it is a dead spot on the commutator shaft.
 
Shot thru said:
This motor is integrated into the gear box so I don't see how it could be swapped out. I am thinking it is a dead spot on the commutator shaft.
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Sounds like the motor is shot or almost shot if it struggling on both thin and thick material.
 
There is limit to what the little 0.5 amp motor can do. They all work this way. Industrials use 5 amp motors.
 
Shot thru said:
This motor is integrated into the gear box so I don't see how it could be swapped out. I am thinking it is a dead spot on the commutator shaft.
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It might be... Do the brushes seem to be making good contact? Although that doesn’t explain why it starts working on either material once you get it going by hand. I can’t tell via the internet and I can’t explain it but it if it hums and works after you turn it by hand, it just seems like something in that gear box is lightly bound and causing too much friction for the motor to start from a low torque position. Once it gets rolling it runs fine so I cannot see that being the commutator but perhaps I’m wrong
 
gcr0003 said:
Sounds like the motor is shot or almost shot if it struggling on both thin and thick material.
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He said it sews fine once it gets going. He gives it a helping turn by hand and it punches through both types of material. Sounds like something is binding and once it is running it has enough torque to overcome the bind.
 
Fl Canopy Stalker said:
He said it sews fine once it gets going. He gives it a helping turn by hand and it punches through both types of material. Sounds like something is binding and once it is running it has enough torque to overcome the bind.
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It’s either that or the motor isn’t strong enough. This is fairly common when you’re trying to go through too much material with a lighter duty machine. You motor only has a certain amount of torque and it’s not enough to slowly go through the material. That is why you have to help it get started. Once you’re through the material and have overcome the friction and the initial force as long as you keep the speed up you can continue to punch through the material. I bet as he is sewing if he slowed down slowly he’ll see the motor lock up as well. It’s as simple as the motor doesn’t have enough umph... I only said the motor was likely going out because he mentioned it was struggling to get started on thin material as well.
 
Play around with starting needle positions - i found if i use the wheel to start the stitch until the needle starts to come back up andv then press the knee pedal the motor jumps to life. When I try with the needle all the way up the machine is trying to advance the fabric as well as move the needle. If your holding the thread tag ends and the presser foot spring is clamped tight with a thicker material you are essentially holding the motor from running right away.

Do you need to give it a hand turn when there is no materail under the foot? Bet it starts right up.
 
jhunter13 said:
Play around with starting needle positions - i found if i use the wheel to start the stitch until the needle starts to come back up andv then press the knee pedal the motor jumps to life. When I try with the needle all the way up the machine is trying to advance the fabric as well as move the needle. If your holding the thread tag ends and the presser foot spring is clamped tight with a thicker material you are essentially holding the motor from running right away.

Do you need to give it a hand turn when there is no materail under the foot? Bet it starts right up.
Click to expand...

You are correct. With no load it starts right up. I will try starting the needle in different positions.
 
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