Bandsaw blade welding

g'day this is not the video that i thought i'd be making this weekend i was cutting up some aluminium material today and my bandsaw blade snapped now normally what i do is is i reach up to that hook up there grab a new one fit it and off i go i typically have half a dozen of them sitting up there and then i discovered i didn't have any i'd use them all they're all broken so instead today i'm going to be showing you how i weld up bandsaw blades um you can buy them ready made that's really nice i've got an odd shape or odd sized bandsaw and i had a bad experience once with a with a blade that was braised up it wasn't done properly it broke very quickly and i decided well how hard can it be it turns out it's actually reasonably hard but with a bit of practice and a bit of application it can be done this is the first tool that i've developed for doing this this is basically a strip of flat iron there's a step there and a toggle clamp and i'll clamp the end of the blade in there and run it along and then i should use that edge there to cut it off the blade on my saw is relatively short it's only 1476 millimeters long and so this does it quite nicely if you've got a longer one you might have to think of something else but this is this gives me a a precise length and that helps fit the fit the blade to the saw if it's a bit too long a bit too short it it doesn't work as well so this is how i usually start typically when blade comes off a roll like this it's been oiled to stop it rusting now that's not a bad thing but the problem is you can't really weld with confidence on oiled steel like this so next thing i do is is clean off the ends with some acetone because of the way the jig's made the end should be square so once i can do that i can put that into my my welding jig this is my welding jig it's made out a bit of scrap aluminium nothing terribly complicated about it but that copper block is just the same height as that and so what i'm what i do is i i use these um they're just a wing nut with a with an oversized washer to hold the hold the blade i'll do the same on the other side and then i'll put a run on and run off tab on either side here so that i can start my my arc on on the run-on tab come across and then finish hopefully on the the run off tab and that way i don't get any holes or pits or anything like that on the on the end of the blade so there you can see the the blade to be welded mounted up i've got my tab there tab there i'll start the arc now this blade material is i think it's 0.65 of a millimeter thick it's half inch wide and usually i have the the welder set on around about or 40 45 amps you don't want much otherwise you'll just blow straight through it the copper backing helps keep the bead on the on the reverse side flat it also helps control some of the heat but that lets me go along and unweld once welded the joint needs to be annealed i've slipped the copper block out and then i'm going to loosen off one of the clamps here so that if that it wants to expand while it's being heated up it can okay i just take it up to i just take it up to red heat and then just let it cool like that i'll then take that out and do the next at this point it's worth doing a bit of a a check on what you've got this one is is almost reject first of all you can see here the the the benefit from having the runoff tab a run-on tab okay i've blown a hole in that i haven't blown a hole in here there's a great temptation to just to to get a pair of pliers out and twist these off but you do need to get out an angle grinder or something like that with a thin cutting disc and cut that off properly because if you snap it you could leave a stress razor here these bands are under a great deal of tension when they're installed and so the slightest notch in there will act as a crack initiator and you know potentially fail and this is this is the reason here that this is almost reject i like to get that world bead coming down so i can grind it back flush with the bottom of those teeth if they're not you can potentially have the problem that on on finish material that will just jam up now you know if you if you obey you your three teeth and the rule uh in the in the well in the cut rule that should just be all right but it's one of those things it's a bit marginal try and keep your well beat as small as possible because you've got to grind that back now if i flip that round hopefully you can see the back of that there's very little i've got full penetration but there's very little uh weld build up on there one that's so that's a that's a good thing so what i have to do now is basically cut off these tabs and then using an angle grinder or a linisher or a bench grinder or whatever i've got get that get that down what you're what you're trying to do is grind that so that it's basic the same thickness of the blade which is why you want the good penetration to grind these i've got i've got a piece of water pipe and i use that basically as a support so i'll come along and i'll slice those off but when i'm grinding this i'll have that back against the pipe so that it just gives me a surface to work against this one's a used blade i've re-welded that i find that if they break away from the previous world you can do that quite nicely if they break on the world it could be a bit iffy as you as you grind you do reduce the material thickness a little bit so there is a natural stress riser so trying to to weld that can be tricky these are the two new ones that i made up um as you can see there's plenty of oil on them but not where my joint is so i need to cut those off and then just dress them back to to flush these can be welded up electrically um your resistance world type thing this one here i went a bit too far with the the grinder when cleaning the top edge off there now what you can do with that is is basically cut it there and there and splice in a new piece of of blade uh you can't run it like that because that'll that'll bump over the rollers and do all sorts of horrible things however one thing when when you do an electric world is you you try you're bending it and seeing whether it'll snap and i'm not keen to do much more than that but you know to me that seems that that weld is is is pretty good and will do what we want it to so there you have it there's a welded up blade running your fingers along and remember that after grinding it it is hot so uh let it cool a while that's uh that feels like it's a reasonably uh constant thickness i've i used a hammer just to give it a little bit of a flattening i try not to but that's sometimes it twists a little bit to do that but try this out and see what happens thanks for watching and i hope this has been of interest to people have a go at welding up your own bandsaw blades

Channel: Occasional machinist

Views: 39,393

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Id: x2QIjlUuQ4E

Length: 9min 33sec (573 seconds)

Published: Wed Apr 06 2022