stewmac bobbins and gibson spacing?

[Possum]

my secret....

I use Just For Men hair color, no one can tell, at the jam they all think I'm 29 :-) I also use Popeil's spray on hair to hide missing fur. the only reason I hang around with Greg is he keeps all those panting girls away from me, I can handle 3 at a time but 12 is too many, they take one look at Greg and vanish in droves :-) As you get older your idea of what "old" is keeps going up. I used to think I'd be dead by the time I was 40, now I'm sure I'll be dead by 83, man, I don't even want to KNOW what an 83 year old's idea of old is :-) I think as far as age goes I bet Semour is the oldest pickup maker living, no wait I'm wrong Bill Lawrence is in his late-ish 70s, he's gotta be the oldest living pickup maker, heck I"m still a puppy....

[soundmasterg]

The only reason I hang with you at the jams Possum is because if I didn't listen to your ramblings, you'd go bug John, the owner, and he'd shut the place down until you went away! I don't need any extra women because I've got the one I want waiting for me across the world and we'll be together soon enough, so I'll send all the extras all your way......... (P.S. all those extras were down on burnside with paying customers before the jam...better stay away!)

Greg

[jonson]

old man

shit Possum I'm 60. Still your only as old as who you feel.

[Joe Gwinn]

I don't have the ability to measure pole-piece spacing within 0.3mm so I can't confirm either way.

Get a cheap digital or dial caliper. Then it will be easy. Measure the outsides of the outer holes, then the insides, and take the average to yield the center-to-center spacing.

For instance http://www1.mscdirect.com/CGI/NNSRIT?PMAKA=76367069.

Used tool places often have perfectly good calipers for $15.

[NightWinder]

Lots of insight from you guys........Soundmasterg is gonna get soriasis on his pecker for that one......Ah, the endless itch.

[Peter Naglitsch]

Actually SM bobbins aren't 50mm I figured it out once when they sent me pole spacing specs on their bobbins, they are like 50.3 or something thats slightly over. You'll notice this if you use authentic spec pole screws the heads will bind some on the end holes, the metric screws you guys use fit fine though...

I measured 4 SM bobbins I still have. They are not 50.3mm. So I re-measured them, this time on the flip side. Same result. And the pole spacing…(drum roll please) 49.50 mm!

[Possum]

the final word on SM bobbin spacing....

found the email from Eric:
Dave,
Thank you for contacting us.
Our humbucker kits have a 1-31/32" string spread.
Let me know if I can provide further assistance

Best Regards,

Erick Coleman

[Possum]

more

so what IS gibson spacing typically?

[Joe Gwinn]

f
Our [StewMac] humbucker kits have a 1-31/32" string spread.

That's exactly 50mm.

[Possum]

uh uh....

Used a converter online:
1.968 75 inch = 50.006 25 millimeter
If you are using the metric screw poles that all these guys sell its no problem but use a US 5-40 screw with correct size head on it (vintage correct) the end screw poles will be tight. So that little 6,000th can be encountered......

[Peter Naglitsch]

Let’s say that the SM spec is 50 mm. C’mon. I can’t really believe that 0.00625 mm is gonna make a difference. It’s like 0.0000246 “. One ¼ of a thousand of an inch! But that half mil (almost 0.02) that the real bobbins differ from their specs is definitely going to make a difference.

FYI: 1”=25.4mm

BTW: What is the head diameter of an US 5-40 screw? I use Metric screws because I live in Sweden and I already have the threading tools for metric screws

[Possum]

...........

You didn't really read my post. I am talking about a pole screw that is what was in a vintage PAF, not what stewmac or guitar jones or allparts sells, no supplier sells those size screws. I had my own made because the alloy and particular shape and size of vintage pole screws has a dramatic effect on tone. The screws you can buy all fit nicely in a 50mm cover, but put a vintage size 5-40 fillister head screw in your cover and that .006 difference binds the end screws, it DOES make a difference. I don't have the specs in front of me but I think the heads are .195 diameter, thats inches not metric. So the stewmac bobbins are not really 50mm they are a hair over that. I had my screws made to about .193 wide because I was afraid of running into this problem, glad I did but sure would rather have had them full width.

[Joe Gwinn]

Let’s say that the SM spec is 50 mm. C’mon. I can’t really believe that 0.00625 mm is gonna make a difference. It’s like 0.0000246 “.

More to the point, when Stewmac said that the spacing is 1-31/32", they were trying to be helpful by converting into inches. I bet it's actually exactly 50mm on their drawings. That said, there will be a manufacturing tolerance, so actual bobbins will not be exactly 50mm.

I agree that there is no way that we are detecting any such thing in pickup covers. We couldn't even detect such a thing, never mind measure it.

One ¼ of a thousand of an inch! But that half mil (almost 0.02) that the real bobbins differ from their specs is definitely going to make a difference.

No, it isn't a quarter mil, it's 24.6 millionths of an inch.

US machinists' jargon: A "mil" is 0.001", a "tenth" is 0.0001", and 0.000 001" is a millionth.

Is the "0.02" in millimeters?

What are the corresponding Swedish machinist jargon terms for 0.1mm, 0.01mm, and 0.001mm? (I lived a year in Stockholm.)

BTW: What is the head diameter of an US 5-40 screw? I use Metric screws because I live in Sweden and I already have the threading tools for metric screws

The allowed range of head diameters in #5 Fillister screws is 0.187" to 0.205".


Bottom line: I think we have a tolerance buildup issue. It's time to start measuring actual bobbins, as many as are available, so we can compute the mean and standard deviation of spacings found in the wild.

[Peter Naglitsch]

Sorry Joe, half a mil is my misspelling of a “mille” and that is Swedish machinist jargon for half a millimetre (roughly 0.02”). Sorry if I confused you guys.

What are the corresponding Swedish machinist jargon terms for 0.1mm, 0.01mm, and 0.001mm?

0.1mm is a tenth of a “mille”
0.01mm is a hundred of a “mille”
And 0.001 is a micrometer or µm

Possum: I did really read your post. I just don’t think that a difference in pole C-C measurement of 0.00625 millimetre = 0.000246” will be visible. I can’t se that small differences with my eyes. And they are almost 20 years younger than yours.

But if a cover is made to fit the vintage correct head diameter of 0.195” = 4.953 mm and one try to use the metric screw (the metric screws I have are 0.200” = 5.08 mm, measured a bunch right now) you might get some trouble. I can still fit those 0.200”-head metric screw in the C-C 50mm covers I have in stock.

Bottom line: I think we have a tolerance buildup issue. It's time to start measuring actual bobbins, as many as are available, so we can compute the mean and standard deviation of spacings found in the wild.

I did so and notices a significant difference in real life compared to the spec (49.5 mm = 1.9488” compared to the expected 50mm = 1.9685”). This difference is way bigger that the petty difference we have discussed in C-C measurements.

I lived a year in Stockholm.)

Cool! Where did you live? And when was that?

[Possum]

space....

I think the SM spec they gave me is correct or I wouldn't have the heads binding on the ends, where these bobbin come from and why they are spaced that way I don't know and they sure won't tell me. I have some guitar jones bobbins that ARE 50mm, I'll put some of my screws in one and see if it pops through easily, that would be the tell all.....