Hey everybody. Im in the middle of sectioning some mandrel bent frame rails that we had bent at Art Morrison. I've been searching the forum for about an hour and can't seem to find exactly what I'm looking for. I really need some experienced advice on warpage. We need a varying profile in addition to the mandrel bends on these rails but that means we have to section about 3/4 of the rails a lot of welding... Since they were bent they were already under a lot of tension before they were cut apart and then adding in all of this new needed welding I'm really worried about them springing out of shape when they are cut loose from the jig. So far I havent done any major welding - I put the rails in jigs to keep them from moving in any way. Then I cut the rails apart where they needed sectioned and placed all of the pieces where they should go and beveled/tacked them in place. How should I weld them? A long time ago I think I read on here that you hammer while you weld to release springed tension in a situation like this. Is that right??? I figured I would weld in 1-2 inch lengths and jump around the tig to keep the flex down but Im worried that isnt enough. The last thing I want to do is go through all of this careful jigging and patient welding just to have to put the rails on a frame machine to straighten them back out (at best).. So to the experts, how do I weld up a jigged plate pattern and keep the final boxed product from snapping into a warped shape when I cut the jigs off?
Here's a picture so you can see what I'm talking about. We cut right in the bends; as you can see 2 inner bends have been cut out and moved down. In addition to that as you can see we've sectioned lateral bend areas as well. Plus welding that full length...
If it were Me I would first get alot of offsets for later measurements(side to side and height. Then I would start welding about 8" from the very end on both sides. Then find the middle and do the same. Then back to the rear starting again 8" fwd where You started and weld back to that and tie in on both sides like before. Do the same at the mid point 8" fwd welding back and tie in. Take Youre time. This process is called backstepping. Repeat this tll complete, let it completly cool. I will pull some but with heat and water You can shrink it back exactly wher You have it now. Youre offsets will tell You where it needs to go. Rec tube and pipe moves easily with heat and water. There are tricks to line heating if and when You get there pm Me and I can walk You through it. FEDER
Get all the possible measurements...build a jig that it will firmly sit in with clamps to hold it in place. Weld it up and if it moves...put some heat on the opposite side of the warp. Steel has a memory and can be bent back. I pretty much do this on a daily basis at work. Atleast its mild steel, stainless steel will blow your mind on how much it moves with heat on it!
Thank you for the time guys the advice is much appreciated. Just to make sure we're on the same page with the general rule - does this theoretical model look about right? ----------------------------------------------------- (see photo attachment below) 1) I would begin at location one (welding from left to right) and then weld to the end of the needed welding area. 2) Moving to location 2 - repeat as above (1)^. __ 3) Moving to location 3 - weld an 8" section (left to right). 4) Moving to location 4 - repeat as above (3)^. __ 5) Moving to location 5 - Weld (from right to left) to the end of the needed welding area. 6) Moving to location 6 - repeat as above (5)^. ------------------------------------------------------------------------- That is what I'm hearing you say; does that sound right? Just keep this up, moving inward (while alternating sides in the middle) until fully welded. Then call you docs in the morning about water and heat.
putting it in a jig like you did is your best bet. Might want to also tack on some supports from rail to rail out of some 1/4 inch rod. This will also help to keep things in one place when welding. Jumping around when welding is a must and probably the most important thing. I would check things with a level every so often as you are going along too. Good luck! Jerry
I do a lot of these types of frames and you will almost always get some distortion.I feel that the best way is to fixture the ch***is as rigid as posible then back step as FEDER explained! Hope this helps and happy welding !!
Thanks for the confirmation Schwartz, does it look like I'm understanding the back-step process (see above post)? I'd like to go get started right now but I want to be sure I interpreted FEDER correctly before I leave. If I should keep more distance between welds then I described I don't want get rushed and....TWANG
If the back stepping/back s***ching I was taught is the same you weld a fixed distance at the end of your cuts since 8 inches is what was said that's what I'll say.Now you move to another area say mid joint and weld 8 inches there.You do this in several places skipping over both sides of the frame to give everything time to cool.when you start your second group of weld p***es you start 8 inches away from a previous weld and weld BACK into your first weld.
Stuff moves around from the heat. I jump from side to side, checking often to make sure that it's still in line. It pulls one way and I move so it pulls the other way. I can remember cutting apart the cage on a comp car that needed to be updated. A** owner thought he needed to be in my way while I was working on it. He was leaning on a down tube that I had cut with the saws all as I cut the other side. Tention that was built up in the ch***is from when it was welded, caused the tubes to move when I cut the second tube made the first cut to flex open, then close real quick. The cut grabbed his **** cheek and took enough meat when it closed to have him need s***ches. Did he let out a yelp! Left the shop and didn't come back until the job was finished.
I would cut and weld some square tube uprights to your table make sure they are square to the table --90 degrees and tack weld the frame to them... .....Then weld it up like you are talking about...
Do not rely on any type of clamps to hold anything in place, tack welds are your best friend as far as holding everything in place. Also use tack weld temporary x braces to help hold it square where ever possible but make sure that they don't block access of any joints you need to weld.
I beleive that you are understanding the backstep process. Just don't weld to much at one time! just 2 to 3 inches at a time. Also place lots of tacks along the seams so they stay put as you move along. One more thing don't be afraid to weld for a bit then go have a beer as it is good to let the heat dissapate. Have fun !!
What's the wall thickness of the tube by the way? That's another piece of information that might be good to throw in the mix.
(That roll cage story is a riot... ) Thanks a bunch guys, I'll update you all when we get one welded up - off to do it right now. The wall thickness is 11ga (.12), so just to be safe I'm going to follow the advice to step down to 3" weld lengths. I figure it couldn't hurt. We also got some interesting advice from an outside source. A structural engineer told us to leave some tiny gaps in a few areas for flex that are still unwelded. He said when we cut it off of the jig the gaps will give a place for springed tension to release. So instead of flexing the whole frame it will have small areas of slack to take up the trouble. Then he said just to weld up the tiny gaps off of the jig (carefully) and call it a day. He says he does this on frames and it keeps almost all of the flex under control. Its time
GRIM only use the 1-2 3-4 steps as You have shown and backstep to those points. Welding RIGHT to LEFT. You always finish Youre weld into the start of the previos weld.I agree with SWARTZ tack weld Youre stops. The frame piece will want to go side to side also its going to want to raise up. HSLD line heating is a fancy term for heat shrinking. We used it alot in modular contruction for shipbuilding. The Ja*****e have been doing it for years. We brought over a team of lineheaters from Japan to teach us the process when we built 3 Jumbo ferries at Todd Shipyards in Seattle. Basically its a form of heatshrinking with large torches and water to straighten long angles and I beams after continuous welding has warped them. We in the hobby do it all the time with panels and frames like above. I just applied the name because of the length He was welding. If You are interested look up shipbuilding new construction and search lineheating. You can actually form and get large plates to form radiouses. FEDER
Thanks a million FEDER, you've been a ton of help buddy... To anyone needing this advice who might find this thread in a search. I did everything that was said in this thread except we stepped down to 4" weld sections. I only deviated from everyone's advice by that and leaving 1" gaps every so often like the engineering advice I mentioned before. The p***enger rail only flexed by 1/32" to the left at the rear and the whole rail bowed by 1/16" overall. I think we can live with that. The second rail is fully welded but we haven't cut it out of the jig yet. I'll let everyone know how that one works out (just in case this was a fluke and I need to learn how to do some line heating after all). Also, our camera pooped out.. Boooo I know... But stay tuned for pics I'll fix the camera situation in a couple days.
It's finally picture time! Good news, the next day the other rail came out of the jig about like the first. Here's a few detail shots after I did some metal finishing. I really like how they turned out it's a ball to stand back and eyeball em'. These are all I have for now but it should be enough to see how the whole process came about. Enjoy the pics, you guys helped a lot in turning em' out.
I noticed your location as being KC and the mention of the Modifiers Car Club in your signature. Do you go back as far as when they had the club house in the store front on the southeast corner of 59th and Troost? I'm from that area and that era. Just curious.
Hey GAB, I actually don't know about that location, what else do you remember??? From what I know the first group had a clubhouse that was off of Woodland and then everyone started getting drafted into the service. A few younger guys ended up carrying the club name on and that might have been their new location. I asked a couple of the older guys about it but no one seems to know what happened during those years. Evidently everyone was in the army and are curious too. I don't doubt that you're right though, the club has had a lot of lost history over the years. After the originals went into the service a bunch of new guys came and went and in that time history got lost. I even have some old club shirts and stuff from the 50s with people's names chain s***ched in them that no one knew or have any knowledge of what they drove. "Hobo" for one
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