skychair Posted March 28, 2010 Report Share Posted March 28, 2010 One of the things I need to finish is installing my front sight. I was just going to epoxy it on, cause it was easy. Good idea or not???? What other method? Any assist is appreciated. Link to comment Share on other sites More sharing options...
darrylta Posted March 28, 2010 Report Share Posted March 28, 2010 Is the site threaded, press fit and or set up for pinning. Do you have a pin? -Darryl Link to comment Share on other sites More sharing options...
reconbob Posted March 28, 2010 Report Share Posted March 28, 2010 The front sight is supposed to be tight enough that you have to drive it on. If it just slides on you have a problem. Epoxy will not hold up when the barrel gets hot. What you can do is epoxy it in the proper position and that will hold it so you can drill it and pin it without it moving. Bob Link to comment Share on other sites More sharing options...
skychair Posted March 28, 2010 Author Report Share Posted March 28, 2010 The front sight is supposed to be tight enough that you have to drive it on. If it just slides on you have a problem. Epoxy will not hold up when the barrel gets hot. What you can do is epoxy it in the proper position and that will hold it so you can drill it and pin it without it moving. Bob No threads and no pins. I have 2 sights one slides on All the way with force and a twist, the other slides on about 1/2 way and no further. I dont have the means to drill for a pin. How many mags would it take (semi auto) to heat the barrel enough to cause failure of JB Weld? They use the stuff on manifolds I think. Just thinking out loud. Link to comment Share on other sites More sharing options...
darrylta Posted March 29, 2010 Report Share Posted March 29, 2010 I'd get a pinned GI site and do as Bob says. If you can't drill it yourself, take it to a gunsmith. Another option would be to install the tight site on the barrel with one of Doug R's ring site installation tools and see if it stays put. Either way you'll need the installation tool, or make one yourself. -Darryl Link to comment Share on other sites More sharing options...
Phil Askew Posted March 30, 2010 Report Share Posted March 30, 2010 I have a NOS Sight and a pin. $45 shipped. Contact me at philfordparts@yahoo.com Link to comment Share on other sites More sharing options...
PK. Posted March 30, 2010 Report Share Posted March 30, 2010 If you have no way to drill & pin, use the JB on the slip fit sight- you should be ok on a semi gun. Worst case- it comes off. Correctly executed drilling and pinning needs to be done either in a fixture designed for the purpose, or in a milling machine. Link to comment Share on other sites More sharing options...
reconbob Posted March 30, 2010 Report Share Posted March 30, 2010 A new sight will not yet be drilled for the pin. So if it is a tight fit you can actually get away with not pinning it - until you accidentally knock or bump the sight against something in which case it might move, but you can always tap it back into position. Any sight that has the hole in it is a take-off. I don't know why ordnance would bother to remove the sight from a barrel, because they were not going to put them back on anything, but I've got hundreds of them. Who knows... Bob Link to comment Share on other sites More sharing options...
skychair Posted March 30, 2010 Author Report Share Posted March 30, 2010 A new sight will not yet be drilled for the pin. So if it is a tight fit you can actually get away with not pinning it - until you accidentally knock or bump the sight against something in which case it might move, but you can always tap it back into position. Any sight that has the hole in it is a take-off. I don't know why ordnance would bother to remove the sight from a barrel, because they were not going to put them back on anything, but I've got hundreds of them. Who knows... Bob Thanks for the offers and advice. I made a tool (bolt, heavy washer, wrapped the threads with masking tape) and banged it on, it aint gona move. It would have been easier to JB it. The next thing I may do is the easy take down modification, but I need to think on it. Again thanks to Phil for the front sight offer, and advice offered from others, appreciate it. Link to comment Share on other sites More sharing options...
wwiifirearms Posted April 1, 2010 Report Share Posted April 1, 2010 Anyone ever try heat instead of force? I never tried this on a TSMG sight, but it works on lots of other stuff. Put the sight that won't slide on in the oven and get it up to 300-400 F(not so hot it hurts the finish). Keep the barrel cold. Then see if it slides on. When the sight cools it should shrink and be nice and tight. Since shooting causes the barrel to heat with or before the sight, it shouldn't come loose. Again, I never tried this on a sight, but it works on other things that are normally pressed in place, like bearings on some car parts. -wwiifirearms Link to comment Share on other sites More sharing options...
emmagee1917 Posted April 1, 2010 Report Share Posted April 1, 2010 And put the bbl'd reciever in the freezer the night before. 1) Increases the temp difference making an easier fit. 2) Gives you something to rub your ??? on after it touches the heated part. Chris Link to comment Share on other sites More sharing options...
Stainless Posted April 15, 2010 Report Share Posted April 15, 2010 I would recommend putting the sight in the freezer overnight, that will cause it to expand. I have done this with bearings, an old trick my Dad taught me, and it works well Link to comment Share on other sites More sharing options...
Chromebolt Posted April 15, 2010 Report Share Posted April 15, 2010 Putting the sight in the freezer would make it contract. Not expand. Cool the barrel and warm the sight. Link to comment Share on other sites More sharing options...
Stainless Posted April 16, 2010 Report Share Posted April 16, 2010 I've tried cold and it works with bearings. Cold causes things to expand,, put a Coke bottle in the freezer overnight and you'll see what I mean Link to comment Share on other sites More sharing options...
darrylta Posted April 16, 2010 Report Share Posted April 16, 2010 Stainless, Chromebolt is right on this, heat= expansion, cold = contraction. Haven't you seen the Seinfeld episode where G. Constanza explains shrinkage? -Darryl Link to comment Share on other sites More sharing options...
wwiifirearms Posted April 16, 2010 Report Share Posted April 16, 2010 (edited) About the only substance that expands with cold is water (the can of Coke is mostly water), and even then it only expands when it reaches the freezing point. The unique shape of water molecules forms a crystal structure when they align during freezing which causes them to expand. Water also expands when heated (try boiling your can of coke), which makes water quite special. Steel, like most substances will expand when heated because the molecules vibrate more when heated. It contracts when cooled becaused the molecules vibrate less. Of course at absolute 0 (about -273 degrees C) all vibration would stop, in theory, and matter would take on a whole new set of properties. I'd go into more detail, but it gets into pretty heavy quantum mechanics, and it won't really help you get your front sight on. However, heating the sight and cooling the barrel should help. -wwiifirearms Edited April 16, 2010 by wwiifirearms Link to comment Share on other sites More sharing options...
Shattered Posted April 16, 2010 Report Share Posted April 16, 2010 (edited) I've tried cold and it works with bearings. Cold causes things to expand,, put a Coke bottle in the freezer overnight and you'll see what I mean ??? I worked for 33 years at New Departure-Hyatt Bearings and it doesn't work with bearings. Coke ain't steel. Edited April 16, 2010 by Shattered Link to comment Share on other sites More sharing options...
emmagee1917 Posted April 16, 2010 Report Share Posted April 16, 2010 Does , however , work with bearing races and ball bearings..IF...your shrinking the OD to drive them into a hub. Also cam bearings , piston sleeves , piston pins , etc., etc. Chris Link to comment Share on other sites More sharing options...
rjb1 Posted April 16, 2010 Report Share Posted April 16, 2010 To be specific, water has the smallest volume/greatest density at 4 degrees C. As it gets colder the water expands and then freezes at 0 C after losing the latent heat of fusion. Ice is approximately 90% as dense as liquid water which makes ice float and breaks Coke bottles in the freezer. As for metals, each has a "Coefficient of Thermal Expansion" which allows you to calculate size changes as a function of temperature change. These values are available in Mechanical Engineering handbooks. For example, aluminum expands about twice as much per degree change in temperature as steel. Engineers use these values to calculate dimensions for appropriate shrink fits. Link to comment Share on other sites More sharing options...
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