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dsraven · 04-30-2020, 10:58 AM

disclaimer:
when welding a "fishplate", like I kind of suggested to take up your gap, there are theories on how it should be done. most pro welder guys who do truck frames etc seem to cut a plate with angled ends then tack weld the fish plate in, then when they weld the sides of the plate they run the weld out and past the end of the fish plate in an arc so the cat's tail run off weld is not inline with the main weld. this is to prevent stress risers at the fish plate due to the heat affected zone when welding.the fish plate angles do not meet at a point, they leave a section intact at the end of the plate that is just squared off (rounded off actually). some larger fish plates have holes cut into the main part to allow welds to be done in the middle of the plate as well. there are a bunch of theories around the whole thing but most that I have seen are on big equipment and the ends of the fishplates are diamond shaped, so angled in on the ends, and they get welded almost to the end of the diamond then the weld takes off onto the base metal part and arcs away. i asked a welder waaay back in the day and he said " you never weld all the way around the end of the diamond and it is to allow for expansion and contraction of the metal when welding. he called it the haz, heat affected zone. the theory also says not to use a thicker material than the base metal because it can also cause stresses from not moving the same as the thinner base material. use your own judgement on that i guess. one thing I would say, since I have boxed in a frame or two, is to bevel the edges well to allow full penetration of the weld and to weld in short lengths and allow the area to cool before doing another weld in that area. otherwise the expansion from the welding heat and contraction after will warp the frame. one guy I talked to said he lets it cool to the point where he would hypothetically be ok to put his tongue on it. that's room temp I guess. I always weld a bit here and there all over the frame, when I do boxing, in order to let things cool off well everywhere.
anyway, dunno if that just confused you more or not. hopefully not.

04-30-2020, 10:58 AM	#91
dsraven Registered User Join Date: Nov 2010 Location: calgary alberta Posts: 7,858	Re: 58 Apache with C4 Flatout Engineering disclaimer: when welding a "fishplate", like I kind of suggested to take up your gap, there are theories on how it should be done. most pro welder guys who do truck frames etc seem to cut a plate with angled ends then tack weld the fish plate in, then when they weld the sides of the plate they run the weld out and past the end of the fish plate in an arc so the cat's tail run off weld is not inline with the main weld. this is to prevent stress risers at the fish plate due to the heat affected zone when welding.the fish plate angles do not meet at a point, they leave a section intact at the end of the plate that is just squared off (rounded off actually). some larger fish plates have holes cut into the main part to allow welds to be done in the middle of the plate as well. there are a bunch of theories around the whole thing but most that I have seen are on big equipment and the ends of the fishplates are diamond shaped, so angled in on the ends, and they get welded almost to the end of the diamond then the weld takes off onto the base metal part and arcs away. i asked a welder waaay back in the day and he said " you never weld all the way around the end of the diamond and it is to allow for expansion and contraction of the metal when welding. he called it the haz, heat affected zone. the theory also says not to use a thicker material than the base metal because it can also cause stresses from not moving the same as the thinner base material. use your own judgement on that i guess. one thing I would say, since I have boxed in a frame or two, is to bevel the edges well to allow full penetration of the weld and to weld in short lengths and allow the area to cool before doing another weld in that area. otherwise the expansion from the welding heat and contraction after will warp the frame. one guy I talked to said he lets it cool to the point where he would hypothetically be ok to put his tongue on it. that's room temp I guess. I always weld a bit here and there all over the frame, when I do boxing, in order to let things cool off well everywhere. anyway, dunno if that just confused you more or not. hopefully not.