Crane Pedestal I Warped

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https://www.dropbox.com/s/g61czuqal0...estal.png?dl=0Hi folks,That link up there is a pedestal I'm making. I'm looking for some pointers with it. I'm far from a welding expert, I'd say I'm fair at best. I turn wrenches, and occasionally weld - when I have to

. Anyhow, this is probably the largest welding project I've done to date. Its for a small crane for my service truck. The picture shows one end of the pedestal. The other end is going to be the same. I'm making  it out of 1/2" mild steel plate and a 8" diameter tube with 9/16 wall thickness. The tube is actually a tube from a concrete pump. Also, some gussets I cut from 1/2 plate also. The picture is a pretty simple drawing showing 2 gussets, a tube and a plate. How I did it was, I welded the tube to the plate first, with 6010 roots and 7018 passes until it looked good. Then I added the gussets, with the same technique. When I was done, my welds looked ok, some needed fixing, but I warped the hell out of the plate, to the tune of about 1/4" up on each corner. I didn't even see this was happening, until it was too late. I'm just doing this on my workbench, not on a flat steel table. I mean, my workbench is more or less flat, but it's just a wooden bench. The other end, I'm just getting started on. I have it tacked into place, and I'm putting down little 1" - 2" welds kind of in a criss - cross pattern around the tube to keep the heat under control, and it's not only tedious, but it's looking like crap. I could really use some pointers here on what I can do to keep that warpage under control. Someone else from another group suggested I cut a hole in the plate, going up to the middle of the hollow tube. I could absolutely do that, but I think that would make the plate weaker? I'm certainly out of my element here, and would appreciate any and all comments. Thank you.
Reply:How will it be mounted( as far as a bolt pattern)? Size of plate? If the plate is large enough and the area your mounting to is strong enough, the bolts may pull it down ok. Heating the underside and rapidly cooling may or may not work because of the gussets. Some warp is going to happen when welding one side only. In all honesty, a 1/4" of warp on the corner isn't all that bad considering the relative thinness of the plate with an 8" tube welded to it . Using a 6010 " root" on a fillet weld is a waste of time in my opinion as well. In a perfect world pre stressing the plate and tacking everything up including gussets before welding is the surest way to prevent warp.
Reply:The crane is mounted to the pedestal with (8) 1/2” bolts. Under the body of the truck there is a frame extension that the bottom of the pedestal mounts to where (6) 9/16” bolts will be used to attach the pedestal to the truck. The plates are roughly 14”x14”. The joints are all single bevel. I wanted to get as much penetration as possible, so I beveled the end of the tube and the welded edges of the gussets. What do you mean by pre-stress? Should I have bent the plate a little the other way before I started? It’s kind of bowl shaped now. I have no idea how I would do that. I’m now wondering if I laid a bead or 2 on the opposite site of the plate, where the tube bead is. after I welded the tube, and before I welded the gussets. Maybe that would warp it back to where it should be. Then I could weld the gussets, and grind off the “extra” bead. Or, I could just bolt it down as-is


Reply:I can't open you pic. Anyway. I made a crane mount too with gussets. I tacked the gussets in before I did any full welding on the base plate to the tube. This helped quite a bit. I still had a little warping but not too bad. I have a pic here somewhere. I will post it. I also clamped my baseplate to my steel table.T.J.www.tjsperformance.comDynasty 300 DXHTP 240HTP Microcut 380Hyperthem 85JD2 Hyd Bender and HF Hyd Ring Roller all in one =(Frankenbender)Bpt. Mill/DRO4' x 8' CNC Plasma TableInstagram: tjsperformanceYT: TJS Welding and Fabrication
Reply:A hole in it wont weaken but with stuff like this,,,, no bevel,,, no root pass, simple 1 pass of weld.www.urkafarms.com
Reply:Yes pre bend the plate. Shim the center and clamp the edges would do that. Ideally you would tack the tube to the plate, tack the gussets in place and skip around when welding.  Between welding the tube first without gussets in place and from what it sounds like, putting excessive weld( and extra heat), it warped more than expected. The beveling in this case wasn't needed. I would bolt it up and gradually tighten the bolts in increments and see how it turns out. Depending where the bolts are in relation to the gussets, it will most likely pull the bow out of it.
Reply:If that base plate is bent,, forget about looking backward, (unless you do another one)Let's look forward.  You say you got 1/4" of distortion, simply cut some spacers, and weld (small welds, no 3-pass stuff) them under the base.With the spacers, the base is functional, you can use it, install it, and go to work.Just let this be a great reminder of what multi-pass welding of unsupported steel can do.
Reply:Pic.

I CNC plasma cut my plates. Then I tacked the gussets in like others are stating. I also clamped what I could to my table.Last edited by TJS; 2 Weeks Ago at 09:47 AM.www.tjsperformance.comDynasty 300 DXHTP 240HTP Microcut 380Hyperthem 85JD2 Hyd Bender and HF Hyd Ring Roller all in one =(Frankenbender)Bpt. Mill/DRO4' x 8' CNC Plasma TableInstagram: tjsperformanceYT: TJS Welding and Fabrication
Reply:

Originally Posted by SweetMK

If that base plate is bent,, forget about looking backward, (unless you do another one)Let's look forward.  You say you got 1/4" of distortion, simply cut some spacers, and weld (small welds, no 3-pass stuff) them under the base.With the spacers, the base is functional, you can use it, install it, and go to work.Just let this be a great reminder of what multi-pass welding of unsupported steel can do.
Reply:I fabbed a motor adapter for a special gearbox we used in the smelter, I tacked it up & sent it to be welded while working on some other ideas for driving that box, the adapter was 1/2 HR 1018 steel plate, it was about 12x12 give or take, a vertical plate the gearbox mounted on, horizontal plate for the motor to mount & two gussets, much like your project, I got the thing back & it had been welded SO HOT that it warped and was not salvageable, it pulled over half an inch on each side. The guy that welded it was a good friend, but I found out that that job was a little above his knowledge level, he welded 1/8" lohiat 180 amps or more, his normal job was welding new ends on punch bars for the smelter, they were about 1 1/8" octagonal steel.NRA LIFE MEMBERUNITWELD 175 AMP 3 IN1 DCMIDSTATES 300 AMP AC MACHINELET'S GO BRANDON!"Those who would give up essential Liberty, to purchase a little temporary Safety, deserve neither Liberty nor Safety.” BENJAMIN FRANKLIN
Reply:It doesnt need as much weld as one might think at first glance. Doesnt need 1/2 both sides. Might not need 100% either.www.urkafarms.com
Reply:Here is something just general in nature and not exact but for lifting and crane stuff.  Factory engineered with book learned engineers can design some stuff up to the limits, some care is used in servicing special stuff to note the specialized bolts etc. I am all about shaving and saving some but I rarely design in such a fashion that it places some ultimate stress type thing on highly engineered special connection etc.  Adding another bolt can solve a lot of problems and I really dont stock grade 8.   At one point when I had ubber wholesale pricing didnt stock 2 either but I oversee most general work and really dont have untested guys bolting heavy equipment up unsupervised  etc.   We also dont do the engine work and service quite the amount of job shop stuff as back in the day so I do use some grade 2 in the hi use sizes.  Nothing wrong with a hardened bolt to bolt a mud flap back up but its not a requirement.   While I might have a bit of a reputation for salvage which I do I replace a lot of bolts. Everything loosened,,, or replaced, especially small cheap sizes, lubed and most can tighten with fingers then common combo wrench, real simple stuff but in the event we do it twice which is usually the case its easy the next time.Last edited by Sberry; 1 Week Ago at 12:34 PM.www.urkafarms.com
Reply:I solve a problem,,, or hope to that was a regular event with 4 more new holes the other day.   They had tried to do it with 1 and some adjustment from the factory it just wasnt holding up and I add another bolt to each point as well as drill tight hole for it to allow for real tightening with hardened bolt.www.urkafarms.com
Reply:Well I obviously shoulda talked to you guys beforehand. Lots of good tips guys thanks for all the ideas. I welded up the other end by welding the gussets to the tube first, and then tack the tube and gussets to the plate, and go to town. A little on one side, a little on the other. Looks ok. Still warped a small amount, but not nearly as bad as the first part. When I bolt it up, I’ll see how much the warped end gives. I might put a washer or 2 under each bolt to make it as even as possible, without bending the frame members below.