Cross Frame Welding

[sled_dog]

I know I've seen it noted before that welding a straight line across a frame is a bad idea, but I want to discuss it again. Is this really such a bad thing? Yeah I know, creates stress point or some such stuff. I did it on my S10 before I remembered that its been said you shouldn't. The frame is fully boxed in the front section and I am strengthening along the framerails(I don't trust them with the SFA or pulling with the front end). Not to mention I've extended the front framerails about 7", so to do this I had to weld across the frame(though at the end of the rails). So is it really an evil thing to weld across the frame? I know I've seen it done a couple times and can't say I've ever seen anyone have a problem with it, but it may have just been luck.

 

[MNorby]

I extended the frame on my yota bogger truck then fish plated (sp) it to reinforce. I also spliced 2 frames together on my black truck and that was an angle cut to meet the frames and is between the rear axle front spring mount and crossmember and its been like that for 5 years now and not a problem.

 

[sled_dog]

angle cuts and diamond shapes are the key I think. I am thinking what I have done will be reinforced with a large diamond shaped piece over it all(I know the front frame extensions will be). And on the other framerail(hasn't been reinforced yet) I will cut the ends angled.

 

[Kiwi John]

If you can plan ahead on frame extensions then internal sleeving with plug welds is a good strengthener plus using half-lap joints is going to help too.
Fishplates, gussets, angles.. put 'em all in whenever you can.
If you're going to weld across the whole frame then strengthen it however you can, always IMHO.

 

[sled_dog]

Yeah I extended the frame 7" forward and there is about 8" in the framerails, plugged welded to the frame.

 

[DavidB]

crack pix

ANYONE GOT A RECOMMENDATION FOR A GOOD FREE PROG TO RESIZE?!

here's some pix of a harrow bed that came in today. cracks all over it. every one is where a brace, bracket, gusset, weld, or hole ends or begins. 2 close to each other make it worse. this is a C channel frame, boxed is more resistant to cracking. also this may be heat treated, i don't think auto frames are. this is prolly the reason rivets or bolts are used sometimes - doesn't create a fracture point as bad as a weld. really, welding across a frame isn't recommended, but sometimes it's ok, sometimes it will cause a crack for sure, and sometimes it can be dangerous. just like everything else, look at it, think about it, be careful. if you're going to have fracture points, spread them out, don't put 2 close to each other. diamond or round shapes are good, or just cut the ends at 45* or more to split up the ends of the welds. also helps to carry the weld a little past the point of the plate when doing this. (see the other pix i posted about this for an example).

my .02. or .50

 

[Kiwi John]

Now, I'm not an expert welder but I would observe the following:
The weld in pic 4 shows little or no penetration.
Thee other pics show poor quality welding ( may even be gas welding?) which hasn't passed thru to the back side.
So the crack wasn't repaired, merely covered over. so it's not surprising that this type of weld has broken as it isnt even as strong as the original metal thickness.
In my experience of agricultural machinery and equipment subject to vibrations, If it breaks once, It'll break there again unless you strenghten the area.
Glad to hear, Sled Dog, that you sleeved your chassis joints.
Incidently, I went to the Rolls Royce repair workshop here in England where they showed us the sleeved repair to the chassis of the famous 'Silver' Silver Ghost. Nobody's perfect!

 

[DavidB]

Now, I'm not an expert welder but I would observe the following:
The weld in pic 4 shows little or no penetration.
Thee other pics show poor quality welding ( may even be gas welding?) which hasn't passed thru to the back side.
So the crack wasn't repaired, merely covered over. so it's not surprising that this type of weld has broken as it isnt even as strong as the original metal thickness.
In my experience of agricultural machinery and equipment subject to vibrations, If it breaks once, It'll break there again unless you strenghten the area.

I should mention that my shop did NOT do ANY of the repairs shown on this
rig. The owner did it himself in the field to get going again. I will post pix after we fix it all the right way.

BTW, notice pic 1&2 (same crack, inside/outside) broke NEXT to the bracket weld first time, repair weld again...because the repair weld simply moved the fracture point.

 

[Kiwi John]

Sure 'Bro'. I wasn't implying that you did. I saw the pics the other day where you showed cracks on a cross-frame weld. The point was, and is, that the HAZ (heat affected zone) adjacent to the weld weakens the metal. Hence need for additional strengthening. We're singing from the same song-sheet here.
Good luck with the repair. Looks like a typical 'farmers' job. Usually harder to repair that POS then the original breakage.

 

[DavidB]

It's cool, no offense taken. Just wanted to be clear.

They always beat 'em harder than ya should. Oughta make 'em stronger in the first place.

 

[DavidB]

This is an old thread but I snapped this pic when I was looking at a truck I'm building a DL for. as you can see, the weld caused the cable to fail. The effect is exaggerated by the material type and thickness. Should have been welded on the top end only. It's a cable step on the back of the truck.