Mesuring Link Size?

[Caliber]

whats a proper or a good/easy way to measure a barrel link? I think it's .288 but then again it might be .284 .... using both frankford arsenal digital dial caliper and a starett standard analog "dial"... dropped it on the floor and damaged it... when the ball-pene hammer fell on top of it I think that might of damaged it a little more than the 3 foot drop onto the cement floor did :-\...

Only marking stamped on it a #13 on both sides... barrel link was installed by jim clark Sr. back in 95 when my unlce was up there on vacation he brought over some guns "both his and mine" to have "tuned".... but they don't have a record listing bushing link size used and have no idea what #13 stamped on it for...

[David Rose]

I'm not sure about the link number, but...

Look at this link:

http://forum.m1911.org/showthread.php?t=33889&highlight=link

Go to post 29 by Niemi24s.

David

[1911Tuner]

Measuring with a dial indicator and doin' the math provides a close estimate, but isn't precise. In order to know exactly, you'll need to measure across pins that fit the holes closely to a light interference fit. Then, subtract half the diameter of each pin.

[David Rose]

Johnny, taking great care to not take a stand against your knowledge...

Wouldn't the ID or the OD be the correct measurement? That is... less than half the existing pin measurement? The pins that will be working against/with that link will not be ones that fit snugly in the holes. They will be the ones in the gun where the link resides. If either hole is oversize, it will change either the compression or the expansion stress on the link based on the pins in the gun, instead of those that fit the holes.

I realize that would make things harder to measure. With calipers that are accurate and have relatively thin jaws, I believe that you can easily get a measurement (with experience with the tool of course) under .002" and maybe within .001". With links spaced basically around .005" apart, then that precision becomes slightly less critical, does it not?

OK, there is also the error created by the small flat on the jaws... That would very slightly increase the measurement of the ID of the link over the true distance.

David, who stands easily correctable

[1911Tuner]

Howdy David. Good points, and correct on the issue of the fit of the link pin and slidestop crosspin...but since link length is determined from center-to-center, the only way to measure one exactly on-center is to use pins. If you have a link of known on-center length...you're golden. But if you're tryin' to find an appropriate link out of a drawerful of unknowns...you don't know what you've got until you know exactly what you've got.

It's the toolmaker in me that won't let me rest with "Close enough for Gub'mint work" I guess. :D

[David Rose]

10-fo sir!

David

[niemi24s]

Hi Caliber: The link with the number 13 stamped on it was originally a +13 link, or one with a hole center spacing 13 thousandths greater than the standard "278" link, or 0.278 + 0.013 = 0.291 inch.

As other posters have said, measuring links is not real easy. Small holes are difficult to measure without well-fitting gauge pins, and if the hole is not round due to wear and/or tinkering they'll only tell you the smallest diameter.

With only calipers to use, the link dimension that is most accurately measured is the distance between the far edges of the holes.

This distance for a mid spec +13 link will be 0.472 inch.

This is the best one to measure simply because the ID jaws (nibs) of most calipers are "pointier" than the OD jaws and will reach farther into the holes.

If you don't measure within about 3 thou of 0.472 it's because the link is worn, your calipers have a problem, or both.

[Caliber]

from top of hole "slide lock button hole" to bottom of small pin hole I have .491. The center piece in-between the 2 holes I have .113

" all readings are consistant on both calipers ".

Pin size on slide stop is .198 , link pin is .155.

trying to guestimate the middle of holes size is near impossible could be .288 , .284 ... .27xx just can't tell by eye... If I had to guess I'd say .288

The link pin has always fit snug and given no problems... slide stop has always been slightly loose, but now that it has been damaged it's very loose. Though I am starting to wonder if it was damaged during shooting, then when disassembled to clean and dropped a hammer on it if that distracted me into thinking it was hammers' fault...

link pin has maybe 1000-1200 rounds on it. which is probably alot ?

[1911Tuner]

Wrong measurement. You need the length from hole center to hole center.

Measure the large hole. Divide by 2.
Measure the small hole. Divide by 2.
Add the two figures. This will represent A.

Measure the distance between the two holes at the closest point. The "Meat" between the holes. This will represent B.

Add A and B. Measuring with a caliper, this method with get you to within about .003 inch. To measure it precisely, you'll need gauge pins...or selected drill rod that lightly presses into each hole...measure across the pins at the widest point...and subtract half a diameter from each.

[Caliber]

So will a .288 link work ? my totals are below


Following 1911tuners' advice the total mesurement comes to: "frankford digital caliper adds up to .292, the starrett dial caliper adds to .291... guessing the top hole got stretched somewhere since the slide stop pin is 0.197 and the slide stop hole on the link is .204 ...


Total measurements:

Link large hole .204
Link Small Hole .156
Link Center .111

Slide stop pin 0.198
Link Pin .154.5

[1911Tuner]

guessing the top hole got stretched somewhere since the slide stop pin is 0.197 and the slide stop hole on the link is .204 ...

One way to know. Measure the hole twice...90 degrees apart. If it's the same in both directions, it's not stretched.

Allowing for the error due to the flats on the caliper jaws...the 288 link will probably work if the gun's vertical dimensions allow. But, .288 is a full .010 inch longer than the mid-spec link. Long links delay linkdown and drop timing...and can prevent it altogether. Bad JuJu. You really need to have somebody in the know have a look and determine which link you need.

[niemi24s]

The measurement you got between the far edges of the holes is a whopping 0.019 more than a mid-spec +13 link. Your "link center" measurement is only 0.001 inch more than a mid-spec +13 link and is within the +/- 0.0015 tolerance for this dimension.

Assuming your measurements are reasonably accurate, this means your link is about a +13 link when in compression but is about a +32 link when in tension!!

DON'T SHOOT THIS GUN WITH THIS LINK!!!

If the +13 link was the proper link for this gun at one time, something must have happened to cause the link to be like this - the gun's either deformed the outer edges of the holes or a previous owner tinkered (filed) with it for some reason.

However, the diameters you posted for the holes are about what they're supposed to be, but one or both must have been taken across the short width of the link. This said because the link's hole cannot be round with the dimensions you gave. 0.111 + 0.204 + 0.156 = 0.471 you said you measured 0.491. And 0.471 is about what a +13 will measure.

Is your 0.491 a typo, did you read the caliper(s) wrong, or is one or both holes that far out-of-round?

And, as 1911 Tuner said, it's virtually impossible to say what the proper link for this gun is without having the gun in hand. Too much stuff involved in the determination.

[David Rose]

OK, Johnny, now I know for sure that I am not understanding this. Maybe it is the flu. I won't breathe on you if you try to help me. And maybe I'm too numb to understand... but I'm trying.

How do the centerlines of the holes effect anything? If you have a pin fitting loosely in the center of the hole, what does it do? It is just "floating" there, is it not? If the pins and link are load bearing surfaces, do they do something when there is no load?

It appears to me that when the link pin and the slide stop pin are either at the outside edges of the link holes (where they are trying to stretch the link), or when they are at the inside edges of the holes (compressing it) are the only times that matter as far as the link is concerned. With a proper setup, it should normally be the stretching that is of real consequence. By this I mean as in a match barrel with lower lugs carrying the barrel instead of "liniking up".

So where am I missing it?

David

[niemi24s]

...when the link pin and the slide stop pin are either at the outside edges of the link holes (where they are trying to stretch the link), or when they are at the inside edges of the holes (compressing it) are the only times that matter ...

You didn't say I couldn't respond, but IMHO you haven't missed a thing, David. The blueprint's laid out to give instructions on how to make the item, and the hole diameters and the distance between those hole's centers determine exactly what you said in the quote!

Your tongue just got in front of your eye tooth and you couldn't see what you were saying!! :D Cheers

[David Rose]

Niemi, you are welcome to respond anytime, you know that. :)

I was referring to Tuner's post, #5, I think. Yeah, my tongue and my teeth and my eyes are all aching. You probably got it right.

David

[Caliber]

the link currently in the gun, was fitted and installed by Jim clark Sr. a few years before he died... the markings on the link state +13... maybe the slide-stop hole is enlarged and oblonged... I'm guessing he put this link in for a reason... being fairly new to 1911's I have no idea what size ".288, .284 etc.etc." a +13 link is nor have I ever needed to change one until now. never had any problems with the pistol always shot tight groups and quite reliably.

[niemi24s]

Hi Caliber: Based on your last post, there's a good possibility the +13 link was modified for proper operation of the gun by Mr. Clark. This is usually done by elongating the large hole either toward or away from the small hole. It can be part of the custom fitting process.

Q: Exactly what is it about this link that makes you think it needs to be changed?

[Caliber]

well I'm unsure if it NEEDS to be changed, but it seems to be fitting slightly more loose and sloppy than it was before hand... That and cleaning the pistol, dropping the link on the floor and a ball-pene hammer ontop of it adds to the concern for change. but it's locking up, cocking, re/dis assembling with no problems it should be okay right? I was mainly concerned about a dent around the small "link pin" hole where the edge of the hammer head hit it.