I picked up a 1951 Singer Featherweight sewing machine recently. It's
in great shape, except that even after applying lots of oil, the shaft
which rotates the bobbin assembly resists rotating through about half
its travel. Presumably this means the shaft is very slightly bent,
although I can't detect any distortion visibly. So, while I can still
turn it by hand, the motor isn't quite up to the task. Here's a photo;
the problem is the light shaft running down the middle:

http://www.lunkwill.org/tmp/singer.jpg

As you can see in the photo, it's about a 1/2" dia shaft held in place
by two cast iron mounts at either end, with cast iron caps at either
end connecting to the bobbin assembly and motor rod. The caps are held
in place by about 1/10" dowel pins, which unsurprisingly can't be
pounded out.

Here are the solutions I can think of, but I'd appreciate your
comments:

1. Remove the shaft by drilling out the dowel pins or perhaps by
careful heating of the caps with a torch to loosen the pins. Then
either:
a: turn the shaft on a lathe so it moves more freely. (How much play
might this introduce?)
b: cut a new shaft and make sure the caps end up at exactly the right
places. (Apparently, bobbin position and rotation needs to be rather
precise)

2. Leaving the shaft in the machine, heat the center of the shaft until
it just starts to become plastic, rotating the shaft continuously as it
cools, so that the mounts themselves ensure smooth rotation. Potential
problems would be twisting of the shaft causing the caps to be at the
wrong angles, and expansion of the shaft preventing any rotation while
it's hot.

-J

I don't think that application of heat is a good idea. You stated you can't
visibly see any distortion. Are you sure the resistance is caused by the
shaft and not in another part of the bobbin assy.? What type of metal is the
shaft? You might want to speak with someone who is familiar with restoring
old sewing machines.

-Tom

"Jason" wrote in message
oups.com...
I picked up a 1951 Singer Featherweight sewing machine recently. It's
in great shape, except that even after applying lots of oil, the shaft
which rotates the bobbin assembly resists rotating through about half
its travel. Presumably this means the shaft is very slightly bent,
although I can't detect any distortion visibly. So, while I can still
turn it by hand, the motor isn't quite up to the task. Here's a photo;

On 26 Mar 2005 14:00:38 -0800, the inscrutable "Jason"
spake:

I picked up a 1951 Singer Featherweight sewing machine recently. It's
in great shape, except that even after applying lots of oil, the shaft
which rotates the bobbin assembly resists rotating through about half
its travel. Presumably this means the shaft is very slightly bent,
although I can't detect any distortion visibly. So, while I can still
turn it by hand, the motor isn't quite up to the task. Here's a photo;
the problem is the light shaft running down the middle:

Check for pieces of thread in the mechanism, Jason. If none,
disassemble each piece connected to that rod and run it through
the range of motion again, looking for the actual area which is
causing the binding.

When I picked up the old Universal machine (ca. 1930s), it was having
a hard time running. I adjusted the angle of the motor so it wasn't
pushing the armature into a worn bearing and it spun 3x faster. After
a quick oiling, it ran like a new machine. Five bucks well spent.


http://www.lunkwill.org/tmp/singer.jpg

As you can see in the photo, it's about a 1/2" dia shaft held in place
by two cast iron mounts at either end, with cast iron caps at either
end connecting to the bobbin assembly and motor rod. The caps are held
in place by about 1/10" dowel pins, which unsurprisingly can't be
pounded out.

That proves how seldom they went bad.


Here are the solutions I can think of, but I'd appreciate your
comments:

1. Remove the shaft by drilling out the dowel pins or perhaps by
careful heating of the caps with a torch to loosen the pins. Then
either:
a: turn the shaft on a lathe so it moves more freely. (How much play
might this introduce?)
b: cut a new shaft and make sure the caps end up at exactly the right
places. (Apparently, bobbin position and rotation needs to be rather
precise)

2. Leaving the shaft in the machine, heat the center of the shaft until
it just starts to become plastic, rotating the shaft continuously as it
cools, so that the mounts themselves ensure smooth rotation. Potential
problems would be twisting of the shaft causing the caps to be at the
wrong angles, and expansion of the shaft preventing any rotation while
it's hot.

3) Neither of the above. Ask a sewing machine repairman what he'd do,
then do that.

If you can't find one to talk to you, keep removing mechanisms from
the shaft until it turns freely and go from there. Those large old
shafts don't bend very easily and they're tougher than the brittle
cast iron around them. Chances are good that it's something else
that's bent, an addition to the shaft, if not a simple thread buildup.

If all else fails, try drilling out the pins and look for scoring. It
could have been run completely unoiled for 30 years.


----------------------------------------------------
Thesaurus: Ancient reptile with excellent vocabulary
http://diversify.com Dynamic Website Applications
================================================== ==

I picked up a 1951 Singer Featherweight sewing machine recently. It's
in great shape, except that even after applying lots of oil, the shaft
which rotates the bobbin assembly resists rotating through about half
its travel. Presumably this means the shaft is very slightly bent,
although I can't detect any distortion visibly. So, while I can still
turn it by hand, the motor isn't quite up to the task. Here's a photo;
the problem is the light shaft running down the middle:

http://www.lunkwill.org/tmp/singer.jpg

As you can see in the photo, it's about a 1/2" dia shaft held in place
by two cast iron mounts at either end, with cast iron caps at either
end connecting to the bobbin assembly and motor rod. The caps are held
in place by about 1/10" dowel pins, which unsurprisingly can't be
pounded out.

Here are the solutions I can think of, but I'd appreciate your
comments:

1. Remove the shaft by drilling out the dowel pins or perhaps by
careful heating of the caps with a torch to loosen the pins. Then
either:
a: turn the shaft on a lathe so it moves more freely. (How much play
might this introduce?)
b: cut a new shaft and make sure the caps end up at exactly the right
places. (Apparently, bobbin position and rotation needs to be rather
precise)

2. Leaving the shaft in the machine, heat the center of the shaft until
it just starts to become plastic, rotating the shaft continuously as it
cools, so that the mounts themselves ensure smooth rotation. Potential
problems would be twisting of the shaft causing the caps to be at the
wrong angles, and expansion of the shaft preventing any rotation while
it's hot.

-J

If you have a lathe, you probably have a dial indicator. I would
verify that the shaft is indeed bent with the indicator - if not,
then a little investigation is in order as to all the components
connected to the shaft - do they all operate freely? If the shaft is
slightly bent, I would suspect that it would be binding 360 degrees,
not just half of its rotation. You may be able to place the bend
close to the "cast base plate" and gently pry to straighten - checking
over and over with the indicator to know how much correction you are
gaining.
Ken.

"Jason" wrote in message
oups.com...

http://www.lunkwill.org/tmp/singer.jpg

As you can see in the photo, it's about a 1/2" dia shaft held in place
by two cast iron mounts at either end, with cast iron caps at either
end connecting to the bobbin assembly and motor rod. The caps are held
in place by about 1/10" dowel pins, which unsurprisingly can't be
pounded out.


Can you lap it in with some fine valve grinding compound?

Tom

On 26 Mar 2005 14:00:38 -0800, "Jason"
wrote:

I picked up a 1951 Singer Featherweight sewing machine recently. It's
in great shape, except that even after applying lots of oil, the shaft
which rotates the bobbin assembly resists rotating through about half
its travel. Presumably this means the shaft is very slightly bent,
although I can't detect any distortion visibly. So, while I can still
turn it by hand, the motor isn't quite up to the task. Here's a photo;
the problem is the light shaft running down the middle:

http://www.lunkwill.org/tmp/singer.jpg

As you can see in the photo, it's about a 1/2" dia shaft held in place
by two cast iron mounts at either end, with cast iron caps at either
end connecting to the bobbin assembly and motor rod. The caps are held
in place by about 1/10" dowel pins, which unsurprisingly can't be
pounded out.

Here are the solutions I can think of, but I'd appreciate your
comments:

1. Remove the shaft by drilling out the dowel pins or perhaps by
careful heating of the caps with a torch to loosen the pins. Then
either:
a: turn the shaft on a lathe so it moves more freely. (How much play
might this introduce?)
b: cut a new shaft and make sure the caps end up at exactly the right
places. (Apparently, bobbin position and rotation needs to be rather
precise)

2. Leaving the shaft in the machine, heat the center of the shaft until
it just starts to become plastic, rotating the shaft continuously as it
cools, so that the mounts themselves ensure smooth rotation. Potential
problems would be twisting of the shaft causing the caps to be at the
wrong angles, and expansion of the shaft preventing any rotation while
it's hot.

-J
Check into the Featherweight Fanatics newsgroup.

"If you would like to join our daily discussions, please send an
e-mail message to "

Several knowledgable and helpful folks follow and contribute to that
group. One is a guy named Jim Sorrell, who has bee repairing and
restoring these machines for many years. We've dealt with Jim and
would recommend him highly.

Thanks for the ideas. I disconnected the shaft from all the other
parts, so I'm sure it's the shaft and sleeves. I'll ask on the sewing
machine lists and see what I come up with, but it looks like the shaft
itself will need to be repaired or replaced.

-J

On 27 Mar 2005 01:00:11 -0800, the inscrutable "Jason"
spake:

Thanks for the ideas. I disconnected the shaft from all the other
parts, so I'm sure it's the shaft and sleeves. I'll ask on the sewing
machine lists and see what I come up with, but it looks like the shaft
itself will need to be repaired or replaced.

If it's slightly scored from lack of oil, you can probably get by with
a honing (or reaming) of the cast iron bearings and a quick crocusing
of the shaft itself. That one pin looked to have a head on it, so
prying it out with a wedge may be a possibility. G'luck!


----------------------------------------------------
Thesaurus: Ancient reptile with excellent vocabulary
http://diversify.com Dynamic Website Applications
================================================== ==

Jason,
Be interested in knowing how this all turned out......
Ken.

Jason wrote:
I picked up a 1951 Singer Featherweight sewing machine recently.
It's
in great shape, except that even after applying lots of oil, the
shaft
which rotates the bobbin assembly resists rotating through about half
its travel. Presumably this means the shaft is very slightly bent,
although I can't detect any distortion visibly. So, while I can
still
turn it by hand, the motor isn't quite up to the task. Here's a
photo;
the problem is the light shaft running down the middle:

http://www.lunkwill.org/tmp/singer.jpg

The friendly university machinist helped me force out one of the dowel
pins, which are indeed tapered. I put one end of the shaft in a drill
press, and using a clamped pencil as a dial indicator noted perhaps a
millimeter of wobble at the bottom, then ran out of time for today.

The bobbin-side end cap was ground in places on the face next to the
bearing, so that seems to account for most of the resistance, although
it still doesn't turn as smoothly as I'd like even without the end cap
forced against the bearing.

The machinist pointed out the tapered cuts down into each end face of
the shaft, and it seemed like he was saying they're useful for checking
straightness and whatnot. But I can't figure how to use them for that
-- seems to me like I'd just clamp one end in the lathe and use a dial
indicator at the other end. (As you can see, I've reached the extent
of my true-Machinist skills)

Anyway, it seems like the options now are some combination of turning
down the shaft, grinding down a bit of the end cap so it doesn't bind,
and just manufacturing a new shaft. There are some scratches in the
journaled shaft surfaces; the machinist kept pointing out the journaled
surface -- is there some trick to producing such a surface on a lathe?

Also, I suspect the end caps are cast iron. All I can tell from Google
is that it's possible to grind cast iron, but it's different from
dealing with normal steel.

As to machining a new shaft, the biggest trick seems like it would be
measuring the angles for the dowel pins, since they're offset by a few
dozen degrees. First I'd have to get the other pin out, which doesn't
seem possible by pounding (even with heating); he said that'd entail
end-milling out the pounded up pin end before I could drill it -- that
just means milling it flat, right? Once the pin is out it seems like I
could line up one end so the drill sinks through the hole, then note
the table rotation required to sink through the other hole in order to
get the angle. But I'm hoping it won't come to that -- I think with
just a tiny amount of reduction, the shaft will go from
finger-turnable-with-a-little-effort to free-spinning, and hopefully
that won't cause noticeable errors in the sewing stitch.

Thanks for your comments! I think that unless fine sandpaper and maybe
the suggested valve grinding compound fix up the shaft, I'll have to
talk one of my engineering buddies into an exchange of food for
machine-shop tutoring.

-J

From A retired Sewing Machine Mechanic.
1st the machine is old hwnce it will be worn, there will be no need to "Lap"
or anything like that.
From 25 yeard of experiance the trouble will be in the Bobbin Race. Remove
that and if the Race itself is mot a "Mirror" finish that's the problem.
Forget all the bearings it won't be there.
First Put the Bobbin into the machine, then hold the Bobbin with your finger
tips as best you can. Turn the hand wheel backwards and forwards slightly is
the Bobbin in your finger tips shudders at all it is the problem.
When you do this action the Bobbin should remain stationary and you should
feel a smooth movement.
To rectify this remove the Bobbin Case not the part that you put the spool
into the Case that remains in the machine, and polish it with "Rouge" (I'm
not sure what you call it in the US)
If the outer ring of the Case Bobbin Case not the part that you put the
spool into, the Case that remains in the machine, Sorry but it's a bit
difficult to explain hope you can figure it out
"Kiwi" Jack
"Jason" wrote in message
ups.com...
Jason wrote:
I picked up a 1951 Singer Featherweight sewing machine recently.
It's
in great shape, except that even after applying lots of oil, the
shaft
which rotates the bobbin assembly resists rotating through about half
its travel. Presumably this means the shaft is very slightly bent,
although I can't detect any distortion visibly. So, while I can
still
turn it by hand, the motor isn't quite up to the task. Here's a
photo;
the problem is the light shaft running down the middle:

http://www.lunkwill.org/tmp/singer.jpg

The friendly university machinist helped me force out one of the dowel
pins, which are indeed tapered. I put one end of the shaft in a drill
press, and using a clamped pencil as a dial indicator noted perhaps a
millimeter of wobble at the bottom, then ran out of time for today.

The bobbin-side end cap was ground in places on the face next to the
bearing, so that seems to account for most of the resistance, although
it still doesn't turn as smoothly as I'd like even without the end cap
forced against the bearing.

The machinist pointed out the tapered cuts down into each end face of
the shaft, and it seemed like he was saying they're useful for checking
straightness and whatnot. But I can't figure how to use them for that
-- seems to me like I'd just clamp one end in the lathe and use a dial
indicator at the other end. (As you can see, I've reached the extent
of my true-Machinist skills)

Anyway, it seems like the options now are some combination of turning
down the shaft, grinding down a bit of the end cap so it doesn't bind,
and just manufacturing a new shaft. There are some scratches in the
journaled shaft surfaces; the machinist kept pointing out the journaled
surface -- is there some trick to producing such a surface on a lathe?

Also, I suspect the end caps are cast iron. All I can tell from Google
is that it's possible to grind cast iron, but it's different from
dealing with normal steel.

As to machining a new shaft, the biggest trick seems like it would be
measuring the angles for the dowel pins, since they're offset by a few
dozen degrees. First I'd have to get the other pin out, which doesn't
seem possible by pounding (even with heating); he said that'd entail
end-milling out the pounded up pin end before I could drill it -- that
just means milling it flat, right? Once the pin is out it seems like I
could line up one end so the drill sinks through the hole, then note
the table rotation required to sink through the other hole in order to
get the angle. But I'm hoping it won't come to that -- I think with
just a tiny amount of reduction, the shaft will go from
finger-turnable-with-a-little-effort to free-spinning, and hopefully
that won't cause noticeable errors in the sewing stitch.

Thanks for your comments! I think that unless fine sandpaper and maybe
the suggested valve grinding compound fix up the shaft, I'll have to
talk one of my engineering buddies into an exchange of food for
machine-shop tutoring.

-J

Jason wrote:
I picked up a 1951 Singer Featherweight sewing machine recently.
It's
in great shape, except that even after applying lots of oil, the
shaft
which rotates the bobbin assembly resists rotating through about half
its travel. Presumably this means the shaft is very slightly bent,
although I can't detect any distortion visibly. So, while I can
still
turn it by hand, the motor isn't quite up to the task. Here's a
photo;
the problem is the light shaft running down the middle:

Thanks for everyone's suggestions! After unhooking everything from the
shaft
(bobbin end and pushrod end), it was still tight. Filing down the cap
at the
pushrod end where it meets the bearing seems to have done the trick.

I've got it stitching now, although the needle broke when I hooked up
the
motor. The needle was old and bent, and I had noticed it hitting the
side of
the hole in the table. That and the take-up spring doesn't seem to be
quite
right. But hopefully with a little more tinkering she'll be right.

(My gf's birthday was yesterday, BTW, and she loved it!

-J