# Is there a machinest in the house?



## Katskitten (Aug 5, 2010)

I have a parts need for my Franklin sewing machine. 

I need a spool peg or rod or shaft or what ever it's called. But I've been unable to find one anywhere.

The problem is the thread size. The peg itself should be the normal size, but the threaded end is smaller and uses a finer thread than anybody else. 
The thread they used is the same as the presser foot thumb screw on every machine I've got. A common thread to sewing machines, but not to the regular world. 

So, I'm at a loss for finding one, and I need one, so I'm looking for someone with a lathe and a super fine threading attachment that could make me one.

I'll pay, I have samples of the thread and I can supply a new tap in rod to thread.

Joe


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## SteveO (Apr 14, 2009)

I suggest go to the vocational highschool they would love to make one for you most likley
Steve


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## Darren (May 10, 2002)

I don't know if this will help. I'd take one of the presser foot thumb screws to a *GOOD* old time hardware store that really stocks hardware and try and see if you can find a nut that will fit it. Once you have the diameter and pitch, maybe you can find something that can be adapted. There are several ways of making threads. Quick and dirty uses a rolling process that presses the threads into the shaft. It's usually the least precise. Next is cut threads followed by ground threads. 

Chances are the original part was made on a screw machine which is sort of like a lathe except adapted for rapid production. I'm guessing it was cut but it could have been ground.

If you can find the size info you can also check and see if gunsmiths in the area do machine work. You can also look for any steam engine collectors in your area. It's not uncommon for some of those to have shops. 

Key is figuring out the size (diameter) and pitch. That tells you where to go next. In some cases some of the industrial suppliers may have all thread that could be used. I'm sort of in the same situation. I figured out I needed to look for a 6x32 threaded rod. I found it even though it's too small for local hardware stores to bother with.


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## Katskitten (Aug 5, 2010)

Darren,

Been to the best hardware store in the area for odd sized stuff. Came close with a metric size, but not close enough.

As for gunsmiths in this area, that's a sad story for another day.

Joe


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## wingnut64 (Jan 12, 2012)

Is the thread smaller than a 1-64 or 2-56?


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## Darren (May 10, 2002)

Katskitten said:


> Darren,
> 
> Been to the best hardware store in the area for odd sized stuff. Came close with a metric size, but not close enough.
> 
> ...


That's interesting. It sounds like you need to find someone with a wide assortment of thread pitch gauges if you can't find a nut that fits. I have quite a few. But there are many like Whitworth, I don't have. Do you have an approximate size and know which metric nut came close?

I'm guessing you've already tried the vintage sewing machine sources on the internet.

The other issue will be finding someone with a lathe set up with the gearing to cut that thread if it absolutely needs to be made. Someone, some place can make anything. At that point it comes down to the money and the willingness of the craftsman to do it. A machinist with the right equipment could adapt a lathe to cut a strange thread. That's going a bit far if they have to cut gears for a one time project. The local guy here made a small drive gear for an overhead crane. He didn't have the correct cutter so he used something close and then offset the work in both directions to get a profile that worked. If you're working with a small thread size, that technique won't work.

I'll call him later to see if he can provide any insight. Having an approximate diameter and the almost fit metric nut size would help.


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## Katskitten (Aug 5, 2010)

wingnut,

I "think" we found it to be close to a 4 but no thread match. And I'm not sure on that.

Daren,
I'm pretty sure this is a specialty screw. Unique to the sewing machine industry.

I can measure the thread and count the TPI if that would help. I'll do that later today.

Joe


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## Allen W (Aug 2, 2008)

If you have an extra screw that fits the hole you could have some one braze or solder a peg onto the screw. Might not be real pretty but should be do able. I just peeked because of the title.


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## Katskitten (Aug 5, 2010)

Allen,

I have thought of that too. But I'd like to try to get one rethreaded first. 


Joe


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## Darren (May 10, 2002)

See if this helps ID the thread.

http://www.gewinde-normen.de/en/sewing-machine-thread.html


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## Katskitten (Aug 5, 2010)

Well, as best as I can measure it it looks to be the 9/64 with 40TPI.

Kind of difficult to read this as it starts out using inch then goes to metric then back to inch.

Joe


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## Darren (May 10, 2002)

Anyone who has a lathe that can cut 40 TPI should be able to make a new one for you. You just have to find them. That thread count is a standard so it is not unusual. 

http://en.wikipedia.org/wiki/Unified_Thread_Standard


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## wingnut64 (Jan 12, 2012)

Katskitten said:


> Well, as best as I can measure it it looks to be the 9/64 with 40TPI.
> 
> Kind of difficult to read this as it starts out using inch then goes to metric then back to inch.
> 
> Joe





Darren said:


> Anyone who has a lathe that can cut 40 TPI should be able to make a new one for you. You just have to find them. That thread count is a standard so it is not unusual.
> 
> http://en.wikipedia.org/wiki/Unified_Thread_Standard




That sure sounds like a 6-40 thread a 4-40 is .112 dia but a #6 is .138 (9/64 is .140, that's it)
It's not exactly common, but standard enough. I think one of my indicators has a screw like that.
As far as it looking like it goes from english to metric, back to english again...........I think what you really have is a 6-40 that has gotten a little "stretched" in the middle, from stress or whatever. A close examination with a strong magnifying glass or eye loop would tell you for sure.
But it's been known to happen with timing chain cover bolts, alternator bolts, head bolts, etc ( don't ask me how I know, lol).


EDIT
You may have been talking about the chart, not the pin, (enlish/metric) that WAS confusing, lol

Maybe you can find something like this to DIY
http://www.amazon.com/High-Speed-Steel-Outside-Diameter/dp/B001GX324Q


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## Katskitten (Aug 5, 2010)

Wingnut,

I was talking about the chart as the thumb screw I measured is brand new and unused.

6-40 hmmmmm, I shall dig around and see what I can find. Remember though I wasn't 100% positive about my measurements. 

Edited to add:
6-40 rang a bell. So I went to my spare gun parts and found a bunch of them. Ruger uses 6-40 screws for their grips. So I tried a couple of them in an extra presser foot shaft and in the Franklin. They worked, but were looser than the originals.
Then I tried an aftermarket presser foot thumb screw with the same results as the Ruger screws. It worked but was looser than the originals.

Out comes the Starrett micrometer for some measurements:
_Original Singer thumb screw;_ .1404" dia X 40 TPI
_Original Franklin thumb screw;_ .1407" dia X 40 TPI
_After Market thumb screw;_ .134" dia X 40 TPI
_Ruger 6-40 grip screws;_ .1352" to .1355" dia X 40 TPI

Yes, I cleaned and zero'd my mic before the measurements  .

So although the 6-40 would work it's just a hair smaller than what is needed.
I think the actual screw is the 9/64" X 40 TPI as I originally thought.

To my knowledge none of the hardware stores around here have any 9/64 X40 or 6-40 of any length
long enough to use. I looked once to fix a set of grips that needed a longer 6x40 screw and found nothing.

Now the spool pin is actually 3/16" so it's a step down to the 9/64 diameter threaded part. So I'm still looking at a custom made part. 
Unless somebody has an old Franklin pin hiding in their junque box.

Joe


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## wingnut64 (Jan 12, 2012)

Katskitten said:


> Wingnut,
> 
> I was talking about the chart as the thumb screw I measured is brand new and unused.
> 
> ...



It's still no biggie to do, especially if you have a pin to run a 6-40 die over. The better ones have a little adjusting bolt on the outside so you can cut a thread deeper or shallower.
I'll look up this stuff in my machinist "bible" when I get home but one of the guys here tonite already showed me the major diameter for a standard 6-40 is .138. The difference in the size diameters you mentioned (.134 and .135) is probably different classes of fits. Class A, Class B, Class C, etc.
You just back off the die or in a lathe cutting it, back off the threading tool so you don't cut any off the starting diameter of the pin, so it comes out .140 instead of smaller.
A lot of times, they sand or polish the burrs down and take a few tousandths of the threads as well.
I can still do it for you, but if you can pick up a die for $10 or $20 and have it around for the next time you need a part and no one has one....it might be something to consider.


OR
The hole it's going in has gotten "wallered out". Re-tapping it with a 6-40 tap MAY fix the threads for you...........or maybe tthread a .145 or .150 pin as a 6-40 and make it nice and tight again (?).



Oops, I forgot about the 3/16 step. That's an easy fix though, too. A 3/16 sleeve with a 9/64 hole drilled thru with a "press fit" may do the trick.
Let me know.


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## Katskitten (Aug 5, 2010)

Wingnut,

Responded to your PM. 

I'm not a machinest, but wouldn't .005" be a bit much for a simple tolerance variation for a screw that small?

Here is the best thing I can think of.

I'll send you a sample of the screw size that fits properly and a couple spool pins.

If you can turn down and thread the pins that would be the simplest way in my minds eye. If not then we back up and go to plan B.

Joe


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## countrysunshine (Jul 3, 2008)

I have no help to offer just this story that is kind of related. 

I recently acquired a 1936 FW. There are no markings for a seam guide. I did have one of those that fasten to the bed but no thumb screw for it. Without thinking it through clearly I put the one that came with my Janome on it but did NOT like the big green plastic head on it and asked my husband to obtain the appropriate thumb screws for me to use with it.

He brought me home one set and they were too large. Today he brought home a smaller diameter but they still weren't right. He sat down ans started messing with it. The metric screw that came with the Janome is a little sloppy. He is trying to figure out exactly what SHOULD be in there. At one point he says, "I can make it whatever you want it to be. I do have a tap and die set." When I looked up he was grinning because he knew THAT wasn't going to happen.

So, now he is a man on a mission. It is an odd thread, I think. Hopefully we get it lined out soon.

Here is hoping you do, too. BTW, he has a lathe. Push comes to shove, he can make me most anything but he really likes me to get OEM.

Good luck.


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## wingnut64 (Jan 12, 2012)

Katskitten said:


> Wingnut,
> 
> Responded to your PM.
> 
> ...


Sounds like a plan. It does make it easier when you can you see and measure something that already fits, or when your working from a print, the vendor has the mating part.
.005" isn't that much even for that size, but it's probably at the limit of tolerance. Literally a "hair". Blonde hair is about .004-.005" LOL

You'd be surprised how many times how many times a print calls out for a specified thread, say 1/2-13 UNC-B (the most common) and they'll call up a week later and say "that's too tight, I need it a little looser for my assembly guys" or something like that. So we figure out what works best for them and make a note - drill .005 bigger. It would be pushing it for a little thread but .003" would be fine.
But the main thing is with threads is the mating parts need a little clearance, but not too much. The finer the tread, the more precise you have to be.
That's one problem with a lot of things I see made now. When the parts are mass produced and outsourced, they get sloppy work sometimes. Too much deburring or not enough. Using worn-out, dull tools instead of sharp new ones. Cheaper, low quality metals and material. That's some of the reasons you'll find such a large variance in a supposedly standard part.

Sorry, I guess I was starting to rant, lol.
I'll talk to you later.


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