anyone use this on their scope screws or anything else? i have a tube coming in today and thought it might work a little better being a litter grip than the blue. Just curious to see if anyone else has used it
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Rifle Scopes loctite purple?
- Thread starter jinxx4ever
- Start date
I used to use blue 242 for just about everything, they have a 243 version now that's supposed to work better with less than perfectly clean surfaces. However over the years I've learned that for 90% of 1/4" or smaller screws, especially small gun screws, purple 222 is all you need. I still never have problems with screws loosening, and I have a lot less small screws end up with stripped out heads. I also really like the "stick" version of medium instead of the liquid for most uses. They also make anti-seize in stick form which is very handy. However, if it's important to your peace of mind the liquid loctite products are the only ones that get tested for mil-spec compliance.
The other one I'm very fond of is green 290, it's a medium-high strength but wicking, so you don't have to disassemble anything so it's great for things already assembled that you know you'll likely never take apart. 220 is the low strength version of 290, but it's much harder to find and spendy.
The other one I'm very fond of is green 290, it's a medium-high strength but wicking, so you don't have to disassemble anything so it's great for things already assembled that you know you'll likely never take apart. 220 is the low strength version of 290, but it's much harder to find and spendy.
The stuff works great. It breaks easier when you disassemble. And with the low torque values of ring screws, it's probably better. Less chance of cross thread and you can clean it up easier. The key thing is it should keep the set torque value and not let the screw back out. I've used it in many applications including eyeglasses with that tiny little screw and it worked flawlessly.
You need to let it cure. At least 24 hrs. Not a torque and go shoot product. Clean threads.
You need to let it cure. At least 24 hrs. Not a torque and go shoot product. Clean threads.
I would say copper for barrel and either for other parts, copper is usually higher temp. They make a while version that isn’t quite as messy but low temp.
I've been using purple for little screws for years. Loctite used to sponsor the race teams and we got the stuff for free. Got to talk to the guys who made the stuff too. They were always doing little tests and showing us how well the stuff worked. Dip a screw in oil, wipe with a rag, apply loctite and put the nut on. Next day try to get it apart. Seems even with crap on it the locker worked. We had to do a lot of fast changes on the indy cars and weren't always able to clean stuff well but I never had a nut or screw come off a transmission....good stuff. I never broke a bolt either. Heat will make removal easy and the temp depends on the particular type. Blue and purple don't need much, red and green need more than 400F. I like it for scope and other small screws on the rifles. Even use purple on the screws for the skins on my Desert Tactical SRS. They came loose the first time I took the rifle out, factory didn't use anything.
Frank
Frank
I've tried purple but didn't see any benefit, so I went back to Blue 242 (which is a lot easier to find too).
As a general rule, using any sort of a loctite on ring screws is not recommended. Wet and dry torque are different, so chances are you are overtorquing your screws if you use loctite. I have used both blue and purple loctite on bases and both worked fine.
ILya
ILya
I am not sure what you mean. Are you suggesting you let the loctite dry and then put the screws in? That just means dirty threads and you'll have no idea what torque you've got on them. Keep the threads clean and degreased and install them using recommended torque values. With quality mounts, I have never had ring caps go loose on me.
ILya
I mean there are loctites you apply and it just stays on the fastener till you install it. Loctite 200-205 if i remember correctly.
I don't think torquing with lube is a problem. In the aircraft industry all the torques given assume lube. I've been torquing my scope mounts and other aluminum parts for decades and as with all things, not overdoing it will get you what you want. The only real problem you'll have with loctite is getting it loose if you use the wrong one. If you are really concerned drop your torque a little. There is information on the net to find the difference between dry and lubed thread torque but I think for the micro screws we're using on scope mounts its a non issue. The important thing is that you maintain a consistent torque. Lube will give you much more consistent torque than dry as well so there is that too.
Frank
Frank
When torquing with lube you should reduce torque by 25 to 40%. Would have to do more research to determine the actual right factor. When things really matter on torque values they always say to torque lubed at least in the manufacturing world.
Time for some physics refreshers...
Two points of force to think about with a fastener
Torque is basically how much rotational force your apply to the fastener, and this value is very easy for us to measure with something like a torque wrench
Axial tension is basically giving your the clamping force on the rings thanks to the threads "stretching" the bolt within it's elastic ability... The bolt being "stretched" is what gives you the clamping force between the ring segments
Torquing with lube WILL change the clamp force achieved if there is lubricant between the threads because it can turn easier and the extra distance traveled will cause a higher axial force
And it will change according to the frictional coefficient of the substance between the threads
I have seen first hand using a load cell to text clamp force that even water in the threads will allow a higher clamping force to be achieved with the same torque values
Another fun fact... Reusing the same fasteners (nuts / bolts) and simply torque then loosen... Torque then loosen... Torque then loosen.... Each time you do this process you will see a lower axial force achieved using the same amount of torque (just from the slight galling of the metal is my guess at the reason but I don't know this for fact)
So if your product was engineered for XXX Torque with "dry" threads, and you put some blue loctite on it... You will clamp the rings down harder than they were intended!!
Now how far off you can be before seeing damage is a question because the fasteners you use... Ring design... And frictional coefficient of whatever you put into it would all come into play for how far over the mark you fall.
What we really need is an engineered answer from the mfg saying a torque spec as lubricated with loctite 243
Two points of force to think about with a fastener
Torque is basically how much rotational force your apply to the fastener, and this value is very easy for us to measure with something like a torque wrench
Axial tension is basically giving your the clamping force on the rings thanks to the threads "stretching" the bolt within it's elastic ability... The bolt being "stretched" is what gives you the clamping force between the ring segments
Torquing with lube WILL change the clamp force achieved if there is lubricant between the threads because it can turn easier and the extra distance traveled will cause a higher axial force
And it will change according to the frictional coefficient of the substance between the threads
I have seen first hand using a load cell to text clamp force that even water in the threads will allow a higher clamping force to be achieved with the same torque values
Another fun fact... Reusing the same fasteners (nuts / bolts) and simply torque then loosen... Torque then loosen... Torque then loosen.... Each time you do this process you will see a lower axial force achieved using the same amount of torque (just from the slight galling of the metal is my guess at the reason but I don't know this for fact)
So if your product was engineered for XXX Torque with "dry" threads, and you put some blue loctite on it... You will clamp the rings down harder than they were intended!!
Now how far off you can be before seeing damage is a question because the fasteners you use... Ring design... And frictional coefficient of whatever you put into it would all come into play for how far over the mark you fall.
What we really need is an engineered answer from the mfg saying a torque spec as lubricated with loctite 243
When it comes to the ring screws, you shouldn't need any thread-locker. But using the blue stuff won't hurt. The tolerances on your torque wrenches are probably wider than the amount (if any) using thread-locker affects the scenario. And if you're that concerned about it, just torque to 18 in/lb instead of 20, or whatever number you're dealing with.
"When torquing with lube you should reduce torque by 25 to 40%..."
Is thread-locker a lube?
And 25% to 40% is a huge margin. I'd love to see some proof that using thread-locker means you over-torque a bolt by 40%. And if that IS the case, that means you'd need to torque a 15 in/lb bolt on a scope ring to 9 in/lbs. But that seems a bit ridiculous.
"When torquing with lube you should reduce torque by 25 to 40%..."
Is thread-locker a lube?
And 25% to 40% is a huge margin. I'd love to see some proof that using thread-locker means you over-torque a bolt by 40%. And if that IS the case, that means you'd need to torque a 15 in/lb bolt on a scope ring to 9 in/lbs. But that seems a bit ridiculous.
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Plinkit you're more or less right about how threaded fasteners work. Repeated tightening and loosening change the length of the fastener by stretching it and that is what changes the ability to hold. There are many aircraft fittings that are torqued to a specific amount of stretch and no allowance for re-torque is allowed. Some fasteners require that you tighten them to a specific torque and then remove them. Then you run them back up to a higher torque for set. Almost all the torque specs I've seen from bolt and fitting manufacturers specifically state that you should lube the threads. Oil, grease or anti-seize are usually the suggested lubes. Loctite always told us that the locker could be considered a lube for the purposes of torquing fasteners too.
On the other hand, the equations and procedures used to determine torque requirements for specific bolt stretch normally ignore anything under about 1/2" diameter as the change in friction between lubed and dry is almost nothing. Consider also that the aluminum rings and mounts we use are normally anodized and that is like a lube itself. I'm thinking its not worth worrying about. I do use a threadlocker because I've seen mounts and rings come loose with the higher recoil stuff like my 338LM. Never had a problem with little stuff like 223 or other non-recoiling rounds. Each must choose for themselves in the end because we can argue all day and never change the mind of any who believe otherwise. Kind of like politics.....
Mostly we should have fun and learn to shoot well.
Frank
On the other hand, the equations and procedures used to determine torque requirements for specific bolt stretch normally ignore anything under about 1/2" diameter as the change in friction between lubed and dry is almost nothing. Consider also that the aluminum rings and mounts we use are normally anodized and that is like a lube itself. I'm thinking its not worth worrying about. I do use a threadlocker because I've seen mounts and rings come loose with the higher recoil stuff like my 338LM. Never had a problem with little stuff like 223 or other non-recoiling rounds. Each must choose for themselves in the end because we can argue all day and never change the mind of any who believe otherwise. Kind of like politics.....
Mostly we should have fun and learn to shoot well.
Frank
@biffj I'm with you on most points
The "stretching" occurs at two different dynamics though... Elastic deformation & plastic deformation
At a lower torque value you are within elastic deformation and you are not actually making the fastener longer permanently. At plastic deformation you are forever making the fastener slightly longer. This goes along with exactly what you mention about some not being given an allowance for retorque, as the bolts are really only one time use when pushed to this point. You will also find some assembly info that ignores final torque and gives a specific stretch for something like a stud, and will be determined by setting up a dial indicator as you tighten.
Even when doing our dry experiments on the load cell within the lower torques that should only be in the elastic range we still see the axial load decrease with each successive loosen and torque is why I made mention of it earlier. I still haven't seen proof of why, but given that lubricated fasteners torqued in the elastic range tend to be more consistent between loosening and retorque is why I believe the change in dry is caused by galling. This also brings up why I agree with you on why so many assembly designs spec lubrication.
We also did our experiments down to 1/4-20 and still saw a smaller scale of the same changes, so I think ignoring everything under 1/2 is not ideal.
As far as the two stage torquing, usually I see the same, but depending on the assembly.... Torquing in stages of usually more to do with the assembly being put together than the fastener.
I'm also with you on anodizing possibly being considered a lube, as it all depends on the frictional coefficient.
I'm also with you on most of it likely being irrelevant to us in shooting...
But...
It all still comes back to somebody with more design knowledge calculating all the elastic & plastic ranges... Then calculating the needed clamping force... Hell we may be simply adding loctite to our higher caliber items because they actually need a higher torque and we get that by lubrication....
I agreed also that it may likely matter not the least bit, but until someone with some serious software gives it actual valid numbers.... We really don't know, but it seemed like the topic was really going that far so figured I would try to share what little I had seen in our tests to help those who want a further understanding.
The "stretching" occurs at two different dynamics though... Elastic deformation & plastic deformation
At a lower torque value you are within elastic deformation and you are not actually making the fastener longer permanently. At plastic deformation you are forever making the fastener slightly longer. This goes along with exactly what you mention about some not being given an allowance for retorque, as the bolts are really only one time use when pushed to this point. You will also find some assembly info that ignores final torque and gives a specific stretch for something like a stud, and will be determined by setting up a dial indicator as you tighten.
Even when doing our dry experiments on the load cell within the lower torques that should only be in the elastic range we still see the axial load decrease with each successive loosen and torque is why I made mention of it earlier. I still haven't seen proof of why, but given that lubricated fasteners torqued in the elastic range tend to be more consistent between loosening and retorque is why I believe the change in dry is caused by galling. This also brings up why I agree with you on why so many assembly designs spec lubrication.
We also did our experiments down to 1/4-20 and still saw a smaller scale of the same changes, so I think ignoring everything under 1/2 is not ideal.
As far as the two stage torquing, usually I see the same, but depending on the assembly.... Torquing in stages of usually more to do with the assembly being put together than the fastener.
I'm also with you on anodizing possibly being considered a lube, as it all depends on the frictional coefficient.
I'm also with you on most of it likely being irrelevant to us in shooting...
But...
It all still comes back to somebody with more design knowledge calculating all the elastic & plastic ranges... Then calculating the needed clamping force... Hell we may be simply adding loctite to our higher caliber items because they actually need a higher torque and we get that by lubrication....
I agreed also that it may likely matter not the least bit, but until someone with some serious software gives it actual valid numbers.... We really don't know, but it seemed like the topic was really going that far so figured I would try to share what little I had seen in our tests to help those who want a further understanding.
The guys who used to work for me seemed to believe that "a good cross thread is better than Loctite"
My car uses center-lock nuts instead of the typical lug nuts on the wheels. Torque specs and procedure is to torque the center lock nut to 600nm (443 lb-ft). Then back off 60-degrees, then re-torque to 600nm. The center locking nut is anodized aluminum. And the spec calls for anti-seize compound on the threads. I doub there is much deformation of the threads since this is a track car and it's meant to take a beating of removing/reinstalling time and time gain. So I doubt there's anything to worry about on a scope ring that is only torqued to a few inch-pounds—especially since we aren't exactly messing with the ring cap screws all the time. You set them and (hopefully) forget them.
If it mattered that much then the scope ring companies wouldnt be sending out little wrenches in every set of rings. Torque them to snug holding on to the small end, give it a brief additional 1/8th turn with the long end and be done.
I don't know if this fits in here or not as it is rather aged, as am I. about 20-years ago.
I don't know if it was a John Deere product or Loctite but on some of the old hydraulic rotary type pumps there would be some fittings that were NPT pipe taper threads and no matter what you did, the nasty fuckers would not line up right.
You needed 1/16th more turn and were afraid of breaking it off or when it fit you didn't know if it was tight enough and would seal or not but with my luck they leaked. no matter if you used Rectum Seal or whatever.
John Deere sold a purple sealer that was anaerobic to put on those type of threaded fittings in John Deere packaging. Green tube.
If the fitting was loose you just put on some of that purple snot and let it sit a while then no leaks. Problem solved.
In order to remove that fitting you had to heat it up or it would come out threads and all. It didn't take a lot of heat but if you didn't heat it up it was stripped thread time so we ALWAYS painted them Red for the next guy or yourself to know that was going on.
I wonder if this new purple is an improvement on that that we used years ago? FM
I don't know if it was a John Deere product or Loctite but on some of the old hydraulic rotary type pumps there would be some fittings that were NPT pipe taper threads and no matter what you did, the nasty fuckers would not line up right.
You needed 1/16th more turn and were afraid of breaking it off or when it fit you didn't know if it was tight enough and would seal or not but with my luck they leaked. no matter if you used Rectum Seal or whatever.
John Deere sold a purple sealer that was anaerobic to put on those type of threaded fittings in John Deere packaging. Green tube.
If the fitting was loose you just put on some of that purple snot and let it sit a while then no leaks. Problem solved.
In order to remove that fitting you had to heat it up or it would come out threads and all. It didn't take a lot of heat but if you didn't heat it up it was stripped thread time so we ALWAYS painted them Red for the next guy or yourself to know that was going on.
I wonder if this new purple is an improvement on that that we used years ago? FM
Foul Mike. You are talking about gooey Loctite 518. If it was more liquid it was 545. The purple 222 is very close to this formula. 545/518 is a thicker sealant than Purple 222, so it fills the gaps in the hydraulic lines and cures anaerobicly. I don't think Loctite gives the same values between the two but the 545 is definitely not as tough as Blue 242/243/2440 and so on but is a little stronger than 222. They keep the color markings pretty close to the ranges that they hold.
As a kid, I used to skateboard and rollerblade. The bolts for the wheels on both always came with a little dab of threadlocker on them. But it wasn't like the stuff you get today in liquid form. When blue Locktite hardens and you remove the bolt, it's a brownish crud. And you have to clean it off before reinstalling. But the threadlocker on the bolts on my skateboards and skates was more like a permanent, reusable stuff. You could reinstall the bolts and it would still hold. And it was a bright blue color even when dry. I wish I knew what they used. I'd love to use that stuff now instead of the liquid Locktite.
Oh, I found it! https://nylok.com/products/nylok-blue-patch
Looks like Locktite also makes a "stick" version, like a glue stick. That might be similar.
Oh, I found it! https://nylok.com/products/nylok-blue-patch
Looks like Locktite also makes a "stick" version, like a glue stick. That might be similar.
As a kid, I used to skateboard and rollerblade. The bolts for the wheels on both always came with a little dab of threadlocker on them. But it wasn't like the stuff you get today in liquid form. When blue Locktite hardens and you remove the bolt, it's a brownish crud. And you have to clean it off before reinstalling. But the threadlocker on the bolts on my skateboards and skates was more like a permanent, reusable stuff. You could reinstall the bolts and it would still hold. And it was a bright blue color even when dry. I wish I knew what they used. I'd love to use that stuff now instead of the liquid Locktite.
Oh, I found it! https://nylok.com/products/nylok-blue-patch
Looks like Locktite also makes a "stick" version, like a glue stick. That might be similar.
I think it was My LArue bases that came with something like this on the screws, only maybe red or yellow.
Ive never used Loctite on rings or bases. I periodically check torque on my rings and have never had one come loose. A properly torqued connection will remain tight.
On my personal firearms I have a tendency to move scopes around quite a bit. I have been playing with Vibra-tite VC3 Threadmate for the last few weeks. It's an interesting compound and maintains its effectiveness over 5x (threading in and out, so says the manufacturer). My experience has been great so far. I thought I'd toss this into the conversation since I have not used purple locktite and perhaps someone here has used VC3 and purple to give a pros/cons review.
I don't use LocTite on firearms anymore, I use VibraTite VC3. Like ThundeRun said you can indeed use it and reuse the same screw 3-5 times depending on it's application. I use it on rail mount screws on a 10-22 up to scope mount screws on 338 Lapua. I've had less screw breakage and screw head mangling with the VC3 than with blue loctite. The green loctite for small screws never really seemed to hold that well for me. I also use the VibraTite VC3 a lot on direct thread suppressor host barrels and on flash hiders, muzzle brakes and suppressor adapters that are meant to be firmly attached and held secure. I think some of the specs for AR type and bolt type rifles call for about 70 ft. lbs. You can get the VibraTited components apart and still reuse them a couple of times. If you have used a bit too much and had to apply a bit of elbow to hand wrench the part on you can use low heat from a heat gun or a butane torch to gently heat the VC3 and the part will spin off. Just did that last night with a suppressor tube retaining ring that I could not get off even with the Liberty hand tool and a strap wrench around that. I had used too much and knew it when I was wrenching it on. A little heat outside on my bench was all that was needed to get the ring off. The heat generated by average suppressor use will not cause anything to loosen. I do have a select fire M-4 style and cooked the heck out of an AWC Thor titanium 30 cal suppressor and while it stayed firm on the big mount it was fairly easy to loosen when the suppressor was just below skin melting temp. If you let it cool all the way it will be snug again. Grainger has this stuff and there are some sellers on Amazon and eBay who sell it.
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