I have just finished my slider fabrication for my rig. I recently saw something about welding to the frame may cause weak spots where the welds are. Since I have a welder, I don't really want to drill holes and bolt them on. Anyone have any experience with this? <img src="/forums/images/graemlins/notooth.gif" alt="" />

Grind and clean as much as possible in the weld area, big fillets and clean steel are your friend. Make sure to connect the welder ground as close to the area of weld as possible and you'll be fine.

Disconnect your battery to be extra retentive, I do.

I heard the shape in which you weld on the frame matters too because the metal expands when you weld on it?

First, make diamond stress plates (shaped like this more or less: <> , at least not straight up and down on the edges) and weld them to your slider outriggers. Then weld them to the frame. Don't weld the points, just the angles. You'll be just fine.

Actually, you'll probably be just fine even if you don't do all that... but just in case...

cool! thanks for the ideas guys. I'll be zapping them on this weekend. <img src="/forums/images/graemlins/kewl.gif" alt="" />

uH, you can do that but its not good for ur machine. you want it on the same piece of metal your welding on but you dont want it closer then 2 or so feet. You get an enormous amount of resistance travelling through the ground if you do. Also weld away from where you place your ground.

Im not saying its not possible iv done it before its just not good to do it alot or for more then tac welding.

as for stress points as long as you have a large surface area most mig welders dont heat the metal enough to cause it to have serious stress issues. (i assume u have a mig machine) I welded my sliders vertical and i havnt had a problem, they are sitting on 1/4"x4"x5" plates.

Thanks for the tip on the grounding. I never knew this. <img src="/forums/images/graemlins/kewl.gif" alt="" />

Just so you know it shrinks. When u weld somethen the metal is hot and fully expanded and when it cools it shrinks and forms stresses. The reason why welding on your frame causes structural problems is because of the shrinking stress. Frames are heat treated when they are done being made in the factory to take this stress off them and make them stronger. So when u weld on them after that ur putting new stresses on them. Its actualy illegal in alotta states. Oh well.

It is a violation of DOT regulations to weld on heat treated frames e.g. semi's...

Most consumer vehicle frames are of mild steel construction..although there are places where HSLA steel is used..

The dead give away on the frame material is whether it is welded construction or riveted construction (on the heat treated frames)...

This document published by the Autrailian DOT is the most comprehensive and informative that I've found... It's for heat treated frames, but very good advice for other frames.

http://www.dotars.gov.au/transport/safety/road/bulletin/pdf/vsb_06_h.pdf

Not sure where you got your information from about not connecting your ground closer than 2' away from where you are welding? The idea of the ground is to provide a current path back to the machine so the closer the better.

Infact if you are welding for me on pressure equipment and I find your ground is more than 36" away from the weld location you just lost your job...