View Full Version : How to tell if your carrier key is properly staked.
I see lots of photos posted where people show keys that are supposedly improperly staked.
The military standard is that the stakes should not distort the side surfaces, and they should result in a removal torque no less than 55 and no more than 100 inch-lbs.
I would bet that many of the "improperly staked" keys are in spec of 55-100 inch-lb removal torque, and many of the home stake-jobs are over 100 inch-lbs removal, and hence out of spec.
So before you re-stake your carrier, perhaps check to see if you can remove the screw with less than 55 inch-lbs of torque. If you cannot, then it is in spec.
Interesting. This site has a collective key staking fetish. I can see a lot of fat wrenches being ordered today. :p
Here is the issue I have with this. Colt stakes theirs from the factory and they are done with a special tool (IIRC).
Some companies stake theirs very lightly to the point that they look correct, but in fact the staking is not contacting the knurled part of the screw head and so it will vibrate loose over time.
In addition it doesn't help that they do not even torque them to the correct spec. The manual calls for 35-40 in/lbs. and should you need to replace the carrier key the only method decribed is the field staking method which is much different from the factory method.
When I have checked questionable keys from companies like BM, DPMS and Armalite they were unquestionably not torqued and staked properly from the beginning.
I see lots of photos posted where people show keys that are supposedly improperly staked.
The military standard is that the stakes should not distort the side surfaces, and they should result in a removal torque no less than 55 and no more than 100 inch-lbs.
I would bet that many of the "improperly staked" keys are in spec of 55-100 inch-lb removal torque, and many of the home stake-jobs are over 100 inch-lbs removal, and hence out of spec.
So before you re-stake your carrier, perhaps check to see if you can remove the screw with less than 55 inch-lbs of torque. If you cannot, then it is in spec.
Don't forget a certain someone who had a loose carrier at that range in Casa Grande after I got back from Africa. ;)
Interesting. This site has a collective key staking fetish. I can see a lot of fat wrenches being ordered today. :p
That guy had all kinds of wrong going on.
The manual calls for 35-40 in/lbs.
I am under the impression that 50-58 in-lbs is correct for the factory. You have a field manual which says 35-40?
Oops. My bad. That was the 23&P w/change 7. The change 8 does specify 50-58 in./lbs.
I am under the impression that 50-58 in-lbs is correct for the factory. You have a field manual which says 35-40?
If one of these set to 55 does not remove the screw, then it is ok - no matter what the stake looks like - because the entire point of the stake is to make removal be 55-100 inch-lbs (no less, but also no more):
http://www.midwayusa.com/Product/718023/wheeler-engineering-fat-firearm-accurizing-torque-torque-wrench-screwdriver
Or if you want to be really sure, just set it to max at 65, to allow for any inaccuracy of the wrench.
I see lots of photos posted where people show keys that are supposedly improperly staked.
The military standard is that the stakes should not distort the side surfaces, and they should result in a removal torque no less than 55 and no more than 100 inch-lbs.
I would bet that many of the "improperly staked" keys are in spec of 55-100 inch-lb removal torque, and many of the home stake-jobs are over 100 inch-lbs removal, and hence out of spec.
So before you re-stake your carrier, perhaps check to see if you can remove the screw with less than 55 inch-lbs of torque. If you cannot, then it is in spec.
When talking about "in spec" it is important to note that EVERYTHING needs to be "in spec." So the bolts for the gas key need to have the correct head diameter. The holes in the gas key need to be a certain size.
So where the problem arises is when someone follows the spec for staking the gas key, but the bolt heads are undersized and the metal from the gas key never touches the bolts. This is why you have to go over the .Mil STD.
Pic is worth a 1,000 words. These bolt heads were on the small size.
http://www.gandrtactical.com/images/archive/BM/Factory%20gas%20key.jpg
C4
Oops. My bad. That was the 23&P w/change 7. The change 8 does specify 50-58 in./lbs.
You can also go above this spec IF you use better quality bolts (which I do).
C4
Torx bolts
http://www.gandrtactical.com/images/archive/BM/Gas%20key%20getting%20staked.jpg
You can also go above this spec IF you use better quality bolts (which I do).
C4
Torx bolts
http://www.gandrtactical.com/images/archive/BM/Gas%20key%20getting%20staked.jpg
That is good reference thank you C4 /
That is good reference thank you C4 /
You are welcome.
C4
Heavy Metal
10-26-11, 14:07
Grant, do you sell those Torx Bolts or can you source them for us?
Grant, do you sell those Torx Bolts or can you source them for us?
I do and I don't. I have about 5,000 of them just sitting here, but have not put them up on the website yet.
C4
Heavy Metal
10-26-11, 14:11
Woud you consider selling me a couple dozen?
Do you like the Torx bolts?
Do you know what Torx size they are?
I like those - as it seems useful to remove screws that were staked too much.
Generally a torque spec is computed to preload the threads to make them lock - and any more can break the bolt.
According to this calculator, you don't want more than 46 inch-lbs. I am not sure how that jives with the 50-58 that is now recommended. Seems like the Change-7 recommending 35-40 may have been the best thing (combined with staking).
http://www.futek.com/boltcalc.aspx
Screws are 8-32-2A and have 0.175 of engagement, Grade-8.
Carrier is 8620 and in the 150,000 to 190,000 psi yield range.
Major Bolt Diameter: 0.164 in
Bolt Thread Pitch: 32
Bolt Proof Strength: 120000 psi
Recepticle Length: 0.175 in
Recepticle Strength: 150000 psi
Applied Tensile Load: 0 lb
k Factor: 0.2
Recommended Torque
34.46 in-lb
(2.87181 ft-lb)
(3.894 N-m)
Resultant Tension:1050.7 lb
Maximum Torque
45.95 in-lb
(3.829 ft-lb)
(5.192 N-m)
Resultant Tension:1400.9 lb
Heavy Metal
10-26-11, 14:12
RSilvers,
Would there be a problem with going to Grade 12?
Grade-12 is not a real specification.
I think the right thing to do is to not over-torque them, and then properly stake them. And by properly stake, I mean work on the process until they can be removed with between 55 and 100 inch-lbs of torque. Less is bad, and more is bad.
Do you like the Torx bolts?
Yes
Do you know what Torx size they are?
Yes
Generally a torque spec is computed to preload the threads to make them lock - and any more can break the bolt.
According to this calculator, you don't want more than 46 inch-lbs. I am not sure how that jives with the 50-58 that is now recommended. Seems like the Change-7 recommending 35-40 may have been the best thing (combined with staking).
http://www.futek.com/boltcalc.aspx
Screws are 8-32-2A and have 0.175 of engagement, Grade-8.
Carrier is 8620 and in the 150,000 to 190,000 psi yield range.
Major Bolt Diameter: 0.164 in
Bolt Thread Pitch: 32
Bolt Proof Strength: 120000 psi
Recepticle Length: 0.175 in
Recepticle Strength: 150000 psi
Applied Tensile Load: 0 lb
k Factor: 0.2
Recommended Torque
34.46 in-lb
(2.87181 ft-lb)
(3.894 N-m)
Resultant Tension:1050.7 lb
Maximum Torque
45.95 in-lb
(3.829 ft-lb)
(5.192 N-m)
Resultant Tension:1400.9 lb
I can tell you that I have taken these torx bolts for well over 60 in lbs and have never snapped a head.
C4
Woud you consider selling me a couple dozen?
Sure (once I get them up on the website).
C4
Sure, if the max recommended torque from the engineering calculator is 46, the bolt won't necessarily break at 60.
Another things is that According to Machinery's Handbook #27, page 1500, torque wrenches are only accurate to +- 25%. So a wrench set to 60 may be just doing 45.
This gas key homodom is going to drive me to the Piston forum! :blink:
Measuring it off the photo, it is a T25.
A T25 can handle at least 140 inch-lbs, which seems good.
patrick sweeney
10-26-11, 15:01
I'm not worried about removing the key screws. I want them to stay put until it is time to replace the carrier key, and then it doesn't matter if I have to put the carrier in a milling machine and cut the heads off.
Agreed, 100 in-lbs is going too far, but as tight as I can get them by hand, and then MOACKS them to death is my preferred method.
Oh, and "carrier key obsession"? If you've seen as many rifles go down from loose keys as I have, you'd be obsessed, too.
Heavy Metal
10-26-11, 15:05
Sure (once I get them up on the website).
C4
Well get crackin' Grant! Those bad boys ain't gonna list themselves you know!?!:smile:
Oh, and "carrier key obsession"? If you've seen as many rifles go down from loose keys as I have, you'd be obsessed, too.
I've seen it happen too, Patrick. I had a carrier bolt break in one of my guns. It's just a regular topic here... THAT... and which lube you're running! ;)
That broken carrier key bolt was a tough on to diagnos. Even got by S.A.W.
.
Just curious, what would be the problem of "over staking"?
It seems that as long as long as you have the screw properly torqued, what does it really matter if it takes 120 in/lbs to loosen the screw, unless you're trying to reuse the screw? Is there maybe a concern of deforming the screwhead which could weaken the screw or maybe deform the Gas Key base?
.
.
Just curious, what would be the problem of "over staking"?
It seems that as long as long as you have the screw properly torqued, what does it really matter if it takes 120 in/lbs to loosen the screw, unless you're trying to reuse the screw? Is there maybe a concern of deforming the screwhead which could weaken the screw or maybe deform the Gas Key base?
If there is more than 100 inch-lbs of removal force needed, then the hex-head may strip out before you can remove the screw. Also, there is no evidence that any key which had even 55 inch-lbs of removal force has ever came loose from shooting the rifle.
I'm not worried about removing the key screws. I want them to stay put until it is time to replace the carrier key, and then it doesn't matter if I have to put the carrier in a milling machine and cut the heads off.
Agreed, 100 in-lbs is going too far, but as tight as I can get them by hand, and then MOACKS them to death is my preferred method.
Oh, and "carrier key obsession"? If you've seen as many rifles go down from loose keys as I have, you'd be obsessed, too.
Ya, getting the gas key off is of little concern to me. Getting it on and keeping it on are the priority.
C4
Has anyone ever worn out a gas key and wanted to replace it? I have so far never wanted to remove one.
Has anyone ever worn out a gas key and wanted to replace it? I have so far never wanted to remove one.
No, but I am sure some have. The most common reason for changing one out is because a primer got lodged in there or it was snapped off.
C4
Heavy Metal
10-26-11, 15:37
Has anyone ever worn out a gas key and wanted to replace it? I have so far never wanted to remove one.
They can be ruined if they hit a hard surface at the wrong angle. Don't drop onto concrete or a similar surface.
I had to take mine off when the front bolt broke. But it had to go to the Machinist to remove the broken bolt shaft anyway...
One thing is for sure - if you do want to remove it, you can find a Torx driver. It is hard to make the case that the screw should be Hex just because they are more common.
Exactly. I am still trying to figure out how the stars and moon align themselves just right for those primers to get in there.
No, but I am sure some have. The most common reason for changing one out is because a primer got lodged in there or it was snapped off.
C4
patrick sweeney
10-26-11, 17:28
considering the low cost, a new key when the rifle gets a second bolt and its third barrel is just preventive maintenance, as far as I'm concerned.
And yes, I've seen keys with torqued-down screws but insufficient staking, come loose just from shooting.
I also had a rifle stop shooting, and it was a loose key - so whatever it had was insufficient.
Robb Jensen
10-26-11, 20:36
FWIW I use the same TorX screw as Grant does and have done so for the past 5-6yrs. I've never had one break or come lose in that time, and I'm talking thousands of keys I've staked and installed. I lap the bottom of carrier keys on a whetstone before installation (ensures that the key is perfectly flat) and I use Rocksett on the bottom of the key and on the carrier key screws after degreasing and torque to 55in lbs and stake with the excellent MOACKS tool from Ned Christiansen. I've yet to see or read of a Milspec about a removal torque requirement, one may exist but I haven't seen it. If I never thought a carrier key might need to be removed due to damage or clogged by a primer I'd just TIG weld the bitch on, but we live in an imperfect world where shit actually happens so I don't do that. YMMV
Suwannee Tim
10-27-11, 20:13
I think the maximum torque spec is to facilitate field removal of a hex head screw without recourse to a milling machine or plasma cutter. In my experience a hex socket head screw can not take much torque before it rounds out. A Torx screw can take a lot more making an "overstaked" screw still removable. BTW, I came across some Torx head wood screws today. Shot about 40 of them, 4 inch long number 10s. None stripped. This is in sharp contrast to some Scrulox (square recess) screws I have been using which striped the recess unless I was quite careful. My vote is for Torx for all socket head applications, replacing square and hex. They are superior to hex and square recess screws. I think it would take a bit of experimentation to learn to stake a screw just so, so it falls in the window of above the minimum and below the maximum torque. If I ever get into carrier key staking I very much doubt I would do such experimentation. I would stake the bitch enough then give some more for good measure. That knowing that if I ever strip the recess out trying to remove the screw I have other methods available, not the least of which is a big 'ole 7 inch angle grinder turning a Norzon Plus wheel, a metal eating beast.
I think all factories should stake to that specification.
proper staking also plays a critical part in keeping the head of the cap screw inside the key when the cap screw breaks. If you've ever had to use a long punch through the cloverleaf to dislodge a broken cap screw head you'll appreciate decent stakes.
Damned StakeLovers.
http://i210.photobucket.com/albums/bb201/trixiebud/hudson067.jpg
Ned Christiansen
10-28-11, 11:16
Counterstaking the screws is a big help. A Starrett automatic centerpunch is the cat's ass for this.
Has anyone ever worn out a gas key and wanted to replace it? I have so far never wanted to remove one.
I've seen them break off, bend, and get deformed when a gas tube came out. I've never seen one wear out from use which didn't have some additional problem.
Damned StakeLovers.
http://i210.photobucket.com/albums/bb201/trixiebud/hudson067.jpg
Is anyone else staring at this wondering what they were trying to accomplish?
Maybe make it look like a Predator was targeting it?
Is anyone else staring at this wondering what they were trying to accomplish?
Maybe make it look like a Predator was targeting it?
Iraqgunz said this was an approved alternate staking method. This is one of my colts that had the bolt snap on me. The guy lapped it, sealed it, bolted it, and staked it.
It's a different, but effective method.
Iraqgunz said this was an approved alternate staking method. This is one of my colts that had the bolt snap on me. The guy lapped it, sealed it, bolted it, and staked it.
It's a different, but effective method.
I learned something new today..
I learned something new today..
If you look at the picture closely, you can see the metal that was displaced into the carrier key heads, specifically in stake 1, 3, and 4 if you were reading the stakes like a book. It is very easy to do with an auto punch versus holding the carrier on the side with one hand, holding a punch with another hand, and swinging a hammer all at the same time. When I get a new carrier, even if it is from BCM or DD, I take a hammer and screw driver to the existing MOACKS stakes, and then counter punch the heads in two places 90 degrees to either existing stakes on each key stake. The thing is never coming off unless the key snaps off with both bolt heads, and then I will use a dremel and one of those broken bolt head removing tools to try to get the rest of the bolt out. If not, a stripped auto carrier is on a short list to replace the spare carrier that is in my gun closet...
You do have a complete spare carrier on hand at all times right?
Is anyone else staring at this wondering what they were trying to accomplish?
Maybe make it look like a Predator was targeting it?
Iraqgunz said this was an approved alternate staking method. This is one of my colts that had the bolt snap on me. The guy lapped it, sealed it, bolted it, and staked it.
It's a different, but effective method.
It's called field staking
https://www.m4carbine.net/attachment.php?attachmentid=8496&d=1305902042
Correct. Because the military (AFAIK) has not yet suffered the wisdom of the MOACKS. So if a key needs to be replaced, you do it as described there.
I did several dozen of our Bushies like that until our MOACKS arrived.
It's called field staking
https://www.m4carbine.net/attachment.php?attachmentid=8496&d=1305902042
A few points:
1) The stress in the screw that results from a particular torque value depends a great deal on the condition and lubrication of the mating threads. Most screw company torque specs require clean, lightly oiled threads.
2) It is important not to exceed the maximum recommended torque because you want to keep the stress in the screw below the "proportional limit" of the screw's alloy. Think of the screw as a very stiff spring you are preloading; if you over stress it, it may actually have less tension even though it may not break.
3) Most high end screw manufacturers like SPS, Allen, Unbrako and others supply their own wrenches for their Allen head screws. The wrenches are designed to fail before the screw head strips. Therefore you have to specify a maximum screw removal torque to insure the screw comes loose before the wrench fails, assuming you want to remove the screw by nondestructive means.
This information was obtained by me from the above referenced screw companies when I did design work involving critical applications of their fasteners.
Clobbersauras
11-13-11, 21:19
So what's your guys opinion of this staking job? So far I have about 3500 rounds through it on an SBR.
http://i143.photobucket.com/albums/r151/clobbersauras/IMG_1074.jpg
I'd check the torque and stake to standard, more from concern over losing a head from a screw than from loosening.
I'd have a greater warm-fuzzy over the material of the BC being pushed into the splines on the screw head, where it's engaging a textured surface...instead of the material of the screw head being pushed outward onto the smooth surface of the walls of the hole in which the screw goes.
I'd also re-torque and re-stake to the standard.
So what's your guys opinion of this staking job? So far I have about 3500 rounds through it on an SBR.
might be just fine... but it seems to me the wrong part got smacked. You want the key material bent into the screw... not the reverse.
Heavy Metal
11-14-11, 08:58
I would counter-stake those punches on the counterclockwise sides of the punch marks displacing metal from the key into the screw, just a hair below the original punch marks. You are basically trying to make a 'stop' for those spots to keep it from unscrewing.
I've seen that method before but that's the first time I've seen (assuming here) that the socket wasn't deformed so that a wrench wouldn't fit.
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