Need to "pin" parts with JB Weld, then weld after...no-no??

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Hey guys!I am working on a project and I have a dilemma:  I need to position a few parts to be welded, three parts to be specific, but I can't hold them in the position they need to be in (on my motorcycle between seat and lower gas reservoir) while they're being welded.  In the pic you'll see a bar, bracket, and another bracket that are all together.  Well, that bar has to be positioned at an angle (in the pic it's just hanging down via gravity), and can only be positioned with the rear seat (removed in pic) pressing against it.  This explains why it needs to be "pinned" and why it can't be welded in place.  :-/SO, I was thinking about using JB Weld to "glue" the parts together in the position they need to be in, then remove it from the bike once it's cured.  Then I could get it welded up nice and strong off of the bike.I would use only a little JB Weld and only on the underside of the bar/brackets area.My dilemma is...will the JB Weld interfere with the welding process EVEN IF I don't weld in the same places the JB Weld is at?Thanks in advance!// Radar // Attached Images
Reply:Hello RadarContact, depending to some degree on the welding process that you plan on using, YES, there will be issues with trying to mix welding with JB weld. The epoxy does a couple of things in the presence of an arc and the resulting weld puddle. It prevents and misdirects the arc, in some instances it's properties combine with and do not move/float to the surface of a weld puddle, thus weakening the weld, and possibly in still other cases the carbon from it's combustion in the welding arc can make the weld deposits hard and brittle. So if at all possible consider some other mechanical means of locating and holding these pieces in place. Good luck and best regards, Allanaevald
Reply:I cannot see your pic because I'm on my phone, but jb weld will leave a residue and interfere with the weld. What type of metal is this? If it's steel can you use magnetic tabs?
Reply:I eyeball stuff like that, make a sharpie mark to help when I can, tack it and check the fit.Tacks are flexible to a degree, so if you're close, you can move it a little and tack again.I know it sounds like a pain - but it works quite well.  The more often you do it, the easier it gets.Good luck Dave J.Beware of false knowledge; it is more dangerous than ignorance. ~George Bernard Shaw~ Syncro 350Invertec v250-sThermal Arc 161 and 300MM210DialarcTried being normal once, didn't take....I think it was a Tuesday.
Reply:Can you pinch it with vise grips?  Or hold it well enough with a magnet?  Heck, even a zip tie?  Fitting parts to be welded is just as much an art as welding itself.Improvise something to get it to stay put.  Then take off the seat and give it a small tack.  Remove your improvisation, and put the seat back on for a final fitment, remembering that the tack can be adjusted a little (if not, grind it down slightly).  Once you've got it, remove the seat again, and weld away.Last edited by rlitman; 01-29-2015 at 02:47 PM.
Reply:Lash it in place with some tie wire at the outsides.  Tack the middle, check fit, remove tie wire and weld the rest.  Or put a couple dabs of plaster on it, then let it harden.  Tack and then chip off the plaster and finish welding.Pinching with 2 Vicegrips sounds easier."USMCPOP" First-born son: KIA  Iraq 1/26/05Syncrowave 250 w/ Coolmate 3Dialarc 250, Idealarc 250SP-175 +Firepower TIG 160S (gave the TA 161 STL to the son)Lincwelder AC180C (1952)Victor & Smith O/A torchesMiller spot welder
Reply:Isn't JB Weld set time measured in hours? How would it be easier to hold it in place for that long than to just tack it in place?And if it's really awkward to fit, maybe you have a buddy or neighbor willing to give you a helping hand for a few seconds?
Reply:Are you the one welding it? What about just tack it in place as it sits?
Reply:having trouble holding or positioning those parts for tacking?  that's how wives/kids and or girlfriends earn their keep.i.u.o.e. # 15queens, ny and sunny fla
Reply:You are talking about using JB weld to pot the part on the bottom, and then weld on the top.   You said you will not be welding in the area where you put the epoxy.    You will probably be OK.The 5 minute JB-Weld will set up quicker and has a lower working temperature which will help you get rid of it after you tack the assembly together.   If you are using MIG or TIG the shielding gas should push any fumes from the epoxy away from the weld.   I'm not sure what would happen with stick.Dan----------------------------Measure twice.  Weld once.  Grind to size.MIG:  Lincoln SP100 TIG/STICK:  AHP Alphatig 200X
Reply:We have the technology."USMCPOP" First-born son: KIA  Iraq 1/26/05Syncrowave 250 w/ Coolmate 3Dialarc 250, Idealarc 250SP-175 +Firepower TIG 160S (gave the TA 161 STL to the son)Lincwelder AC180C (1952)Victor & Smith O/A torchesMiller spot welder
Reply:They make spring loaded removable rivets for the aircraft industry. I believe they are called "Cleeco" or something like that.
Reply:Thanks to all for the advice!(I think some may have missed the main point in the original post -- there is a vinyl seat that essentially covers the bracket, so there can't be any welding in place, including tacking.  However, the seat has to be in place to get the angle exactly right.  That's the dilemma.)Here what I did:-While disassembled, I drilled a small hole (3/16"?) at an angle through the face of the front brace, then...-I assembled everything with the seat in place.  -Used "high technology" duct tape around the bottom "legs" of the bar to pull the bar tight up against the seat at the right angle, then wrapped the tape up & over the top of the seat to hold it in place.-I then went back to my drill hole and continued into the metal bar ~2/3 the way through.To be continued tomorrow...-Im going to try to force a fine threaded screw through both (plate->bar) to hold them together.-Then for good measure, draw a sharpie line across where the bar meets the plate just in case the one screw allows it to "teeter".I'll post some pics of my progress, in case anyone wants to see how it'll work in the end.Thanks again.  Even if the ideas weren't used here, I'll keep them in mind for future projects for sure!!!// Radar //Last edited by RadarContact; 01-30-2015 at 01:37 AM.
Reply:Clay, hot melt glue...Welding/Fab Pics: www.UtahWeld.com
Reply:Like Dave said eye-ball it. Measure the side to side position so it is correct and if the angle is off a little stick a wrench on it and bend it into place. That is twist the rod a little.---Meltedmetal
Reply:Was able to get a screw in it and then I removed it and threw a clamp on it.  We'll tack off the bike, install, then go from there with adjustments or welding it up for good (again, off the bike)!Thanks again to all...I learned a lot of great tips/ideas on this one post!  Great forum, great people!!// Radar //[ATTACH=CONFIG]987961[ATTACH][ATTACH=CONFIG]987941[ATTACH=CONFIG]987941[ATTACH] Attached Images
Reply:And done (the rough work at least)!
Reply:Well Done.Dan----------------------------Measure twice.  Weld once.  Grind to size.MIG:  Lincoln SP100 TIG/STICK:  AHP Alphatig 200X
Reply:Originally Posted by RadarContactAnd done (the rough work at least)!
Reply:Originally Posted by dbstooWell Done.Dan