Heat Treating and Tempering Flat Springs

[Music] well welcome to the cinnabar today we're right in the middle of project working on a heavy-barreled 1876 winchester trying to get it functioning properly so we can shoot it again now one of the issues with it is the set trigger wasn't working properly so when we opened it up we found right away that it was missing one of the three flat springs that operates that set trigger mechanism specifically the center one the big thick one called the knock-off spring unfortunately i had three of them that to choose from and as i was looking through them only one of them is the right contour so before i put that one with the proper contour into the gun i need to use it as a template to bend the other two into position or into the right contour in order to do that we need to heat them up which is going to take the heat tree to out of those springs so we're going to have to re heat treat them and then temper them so if you're interested in that kind of thing we're going to take a few minutes make have a mini how-to episode on heat treating and tempering flat springs okay so here's these three springs we were talking about these a lot of people call them a kick off spring winchester actually referred to them as a knock-off spring this center one here is the proper contour if you look closely you can see this one on the left kind of kicks off to the to the left a little bit my my pointer is magnetic unfortunately and the one on the right kicks off to the right a little so we're going to have to heat those up to bring them back because they're so thick we can't really bend them now some really thin flat springs like like this sear spring here that's so thin sometimes you can if you're real careful you can bend those without um heating them up and losing the heat treat if you're if you're not careful of course you can break them pretty easily and those are pretty easy to make but these these are pretty difficult now let's turn these up on edge a little bit so they that kick off to one side or the others is one of the problems but you can see this one on the left actually right out towards the end where the round spot is it kicks up really hard right there at the end and and so that makes the spring too too uh strong you can't hardly get it all together again you can see how difficult these springs would be to make that they they start out thick down here in the base and they get thinner and then curve up and then we've got this rounded spot up here on the end so the gunsmith that made this one actually made the dimensions really good just didn't quite get the contour right and it's a it's a difficult one this one on the right here it's just kind of a mess you see the the contours completely opposite of what should be um i think this one was probably in a house fire or something and and uh got so it's a red hot that it lost its heat treating temper and just bowed the wrong way that one's going to be kind of difficult to get just that right arc in it but we're going to give it a shot anyway so stick around we'll get over to the torch and get these things heated up and see if we can't get them contoured the proper way okay so i'm getting ready to heat this spring up but i got to noticing that there's all these scratches kind of running in this direction across it the gunsmith that made this just didn't do a real good job of polishing it up when we're done and every one of those little scratches going across here is a potential stress riser whether that spring can can break so we want to get those out of there and get it polished up and and all our polishing marks going lengthwise down the down this thing so we're going to start off with a just a piece of emery paper backed by a file here and start working those down and when we get get close and get those kind of smoothed out then we'll take it over to the buffing wheel and really polish it up real nice [Music] [Music] so okay so it's time to heat up these springs and bend them back into shape and we've got you can use a couple of different types of heat sources you know we can use the um just a little propane torch like this if that's what you have um you can actually get uh map gas which is in a little cylinder like this too and burns a little bit hotter but i prefer oxy acetylene torch since i have one here we can control the flame a little bit better with the oxy acetylene torch um these these uh springs are high carbon spring steel of course and and what makes them a spring steel is is that carbon content and higher carbon contract than just mild steel so when we're working with oxy acetylene torch we want to make sure that we have what we call a carburizing flame so it has excess carbon in the flame so if we've got oxygen and acetylene mixing acetylene has the carbon in it oxygen doesn't and if we have an oxidizing flame which is higher to oxygen then we're going to be robbing some of the carbon out of the spring steel so here's here's how you tell if you have a a oxidizing flame or a carburizing flame we'll fire this up there's three different flames on coming out of the tip there and uh so we'll start that up with the acetylene give it a little oxygen hopefully just a little there we go so you see the the full length flame is out about here and then as we give it a little more oxygen we get this little really light bright flame right here out of the tip it's only a quarter three eighths of an inch long and then we have another flame that we can adjust back and forth and i'm i'm using the oxygen to adjust it but you can do the same with acetylene so if we bring that tip that middle flame all the way back we're neutral um and if we go a little further then we're oxidizing so we want more carbon so uh a uh carburizing flame is one where we've got that middle flame out there a ways about like that so we've actually got a carbon rich environment now that we're heating with okay so we're just gonna this is the one that that tip was bent up quite a little bit and we're gonna we're gonna kind of concentrate on on heating that area up first and bend that see it doesn't take very long now we'll we'll get this on it and this and see if we can't bend that to where it's the right see it's even though it's cooled some it's still soft and pliable i fiddled around there a little longer than i should have okay now we're going to hold it up against this this spring that has the right um contour to it and it is absolutely perfect i don't know if you you can see that or not but now we've got that tip exactly where it needs to be now the other part of this spring that needs to be fixed up a little bit and now it had a little bit of a bend to the left so we're gonna we're gonna heat up that leg it's gonna take a little longer because it's thicker back there we don't want to get just carried away we can take our time a little bit this is a pretty thick spring now you can see it's starting to get a little red in the middle there we want to get it fairly even so that it it doesn't bend just in one spot it really needs to bend more down towards the base of that leg okay now we're we're fairly even we're going to see if we can't bend that over so now we've got a little dog leg in it we're going to go back that out okay so we'll now that one up to it and i think we're pretty darn good shape probably can't see that very well but it looks like it's centered up really nicely right now so we're in good shape there we're going to go ahead and heat this up try to get it good and even all the way across and then we'll we'll quench it in this hydraulic oil right here we'll concentrate some of the heat down here at the thickest part we want to get this to a a cherry red no harder nice thing about this steel is we can tell the heat from the colors okay we're starting to get some red in the thinner parts concentrate it here we don't want any oranges or or yellows in it that's that's too hot we've got it's really hard to get a even there we're just about even with a good cherry red now get that out on the tip a little bit more and we quench okay so there's one down um that spring now is extremely hard but it's also extremely brittle so that's where the tempering process comes in we'll have to draw that back to a consistency that that is still hard but has some flex in it at this point if we put this in the gun and and work that spring it would just snap it's about about like glass okay i'm going to go ahead and do the other one real quick um and and then we'll uh get to the tempering process okay so we've got two hardened springs now and you can see the profile on them is virtually identical even though they started out with completely different profiles now we're going to clean up all that old burnt oil off of them and and take them over to the casting pot and temper them up okay so we're getting ready to temper these springs now and we've got some choices um for the heat source to temper these springs of course if we've got a heat treat oven um that's the simplest way but our oven is for uh color case harding a big oven it's hardly worth firing that thing up uh just to do a couple of little springs like this of course we can use our our torches either oxyacetylene or a little propane torch but it's hard to get it and even heat and and hold it there for a little while while those molecules rearrange themselves um which is what that tempering process does to soften those springs up just a little bit so they've got that give so what i like to do is is use a casting pot and and we can use either either just regular lead or in this case this little casting pot i use here is for uh nighter blueing fire bluing so if we use this we get the extra benefit we get a a pretty blue color at the end which is what we would want if we were using one of the other uh uh mediums as well for for heating and and if you if you don't haven't ever seen one of these this is a color chart that tells you temperatures of metal by the color of the metal so that's very very helpful so we're just about up to temperature now up to 600 degrees where we want to get that kind of a bright to medium blue color and so we're going to get set up here and and show you how we get these springs in the pot and blued up and tempered okay so you can see that kind of a pinkish color on on top of the bluing salts there these are these are actually nighter blue salted it is a little strange to think that something so pink actually turn something blue um if you can see okay here we've got our our thermometer in here and we're right at 600 degrees so we're ready to to dunk these springs in here what i've done is i just got these springs in this wire so that they're not going to touch the bottom they're not going to touch each other and whatnot and then we've thoroughly degreased them uh with acetone and then dried them off one of the things you really have to be careful of with night or bluing salts is getting any kind of moisture in there it'll just erupt those salts out of there and burn the heck out of you if you're not careful so i'm going to put some gloves on real quick here and some safety glasses and then we'll dunk those in there they should be good and dry and whatnot but it never hurts to be careful when you're working around these bluing salts okay so here we go we're going to dunk them in we're right at just a little over 600 now and i'm going to cool it off just a little bit we're just going to leave them in there for a little while you know it more time doesn't hurt at all um in fact the the biggest problem is is too little time you can get it up to the right temperature get the right color but if you don't keep it there for a little while those molecules don't get rearranged and and you don't get a good even temper okay so we've had these in here for about five minutes now a little more let's pull them out and of course we can't see real well because we've got all the kind of stuff off the top of that those bluing salts on them but uh looks like they they've blued up nicely we're going to hang them here let them air dry for a while and cool off and then we'll come back and we'll we'll scrub those off real good with water and then we'll use some wd-40 to to clean the water off of them so they don't rust up or anything okay so now it's time to clean these things off we'll just dunk them in water a little bit get the wire off of them and get them cleaned up just basically getting the bluing salts off of them and then when we get that done we'll get them oiled up so we don't get any rust and they ought to be good to go they look like they're they're pretty pretty light colored the the blue we you know if we were actually going for color rather than the uh just the temper we'd leave them in there a little longer to get that fire blue look got a kind of a chunk of blueing salts on the back there okay so yeah we just got kind of a a real light blue color on there and we'll set that one aside get this other one out of here and of course you don't want to do this right next to your your night or pot or you accidentally flip a little uh drop of water in there and the whole thing blows up on you okay so we'll kind of dry those off and and hit them with some wd-40 and they're ready to go okay so we went from having a couple of springs that were basically useless um you know the wrong wrong uh contour one of them i'm sure the heat treat was gone they've been through a house fire to having two very useful springs now and uh the the moment of truth now is if we can flex these and they they come back to shape and don't break and don't bend then we know we got the heat treat and the uh temper right so both these are doing that and so with if you've ever tried to find a knockoff spring for a set trigger gun and these work in a 73 76 and 86 you know they're hard to come by and if you can find them they're about 75 to 100 bucks a piece so we by knowing how to to heat treat these and and tempering properly we saved ourselves 150 200 bucks so i hope you learned something this was kind of enjoyable for me until we get that other spring back in that 76 and get out there and do some shooting happy trails from the cinnabar

Channel: The Cinnabar

Views: 3,460

Rating: 4.9304347 out of 5

Keywords: Heat Treat, Temper, Flat Springs, Winchester 1876, Set Trigger

Id: dCZMZV1DJ0o

Length: 17min 26sec (1046 seconds)

Published: Fri Apr 09 2021