Don't do what i did.

[DPittman]

So I have one of those Uber cheap 30" sheet metal brakes from princess auto and I was attempting some fixes to some of the well know weaknesses in the unit.

The bending angle is known to flex in the middle especially on full width bends or on heavier gauge stuff. I've seen various videos where other people welded on reinforcing steel on the back side to prevent this. I thought many of them were overkill and was worried that alot of welding would warp the angle. That's exactly what I ended up with, a warped bending angle that has now turned my brake into scrap as it now sits.

I figured 3 flat bar gussets in the angle would be adequate strength but didn't think warpage would be of concern. I was wrong.

The only thing I can think of that MIGHT help is to cut through the middle gusset and hope that might relieve some of the strain. Grinding the surfaces flat again isn't really an option as the angle binds now and there is no way I can see that the angle can be removed.

Suggestions?

 

[Tom Kitta]

when welding warping is always an issue to watch out for.

I am not 100% sure of the exact issue but is there a way to mill the parts back into spec?

 

[DPittman]

when welding warping is always an issue to watch out for.

I am not 100% sure of the exact issue but is there a way to mill the parts back into spec?

Yes I thought warpage wouldn't be a big issue as I tack welded and wasn't doing the whole length but I obviously was wrong.
I think the angle and it's hinges must have been welded in place otherwise taking the angle out and grinding/milling it back straight would be an option. I think unless someone else is able to come up with a better idea, I'm going to have to cut each gusset down the middle and hope that the angle returns to its original position. I would not be surprised however if there is some warpage that remains even after that attempt.
I think my mistake was welding one gusset at a time completely as opposed to tacking them all in position and then welding each one a bit in succession.

Gee I had some other modifications also for this brake that I think were going to make it much better.

 

[SomeGuy]

Generally to minmize warping you need to clamp everything down solid, tack all joints first, then burn things in while keeping heat to a minimum...sequencing is important too, doing the tacks/welds in the right order knowing which direction it will pull things in and doing welds in a way that they resist pulling material.

I'd cut it all out, it should come back a bit and depending on how it warped (can't really make it out in the photos), you might be able to intentionally warp it back straight with your next set of welds.

 

[johnnielsen]

The top member on my P.A. 30" inch brake is just a piece of flat bar. If yours is bent, replace it with another piece. If your new piece needs strengthening, bolt a piece of 2X2X3/8" angle on top of your flat set back a half inch from the bending edge using countersink head bolts. It will be plenty strong then.

 

[DPittman]

The top member on my P.A. 30" inch brake is just a piece of flat bar. If yours is bent, replace it with another piece. If your new piece needs strengthening, bolt a piece of 2X2X3/8" angle on top of your flat set back a half inch from the bending edge using countersink head bolts. It will be plenty strong then.

My problem right now is not the bending bar but rather the angle iron that swings up to meet against that bending bar.
The bending bar itself can flex up of the table also and I already have something very similar to what you just described that I was going to install next. We will see if this thing is salvageable and then I can proceed with my other already made mods.

 

[Susquatch]

If I understand the situation, it is impossible to weld on just one side without warping unless the part is heavily constrained. Even then residual stresses are created.

My instincts would be to do all your structural improvements with fasteners. It's entirely possible that you can even straighten it with strategically placed fasteners and structural additions.

 

[DPittman]

If I understand the situation, it is impossible to weld on just one side without warping unless the part is heavily constrained. Even then residual stresses are created.

My instincts would be to do all your structural improvements with fasteners. It's entirely possible that you can even straighten it with strategically placed fasteners and structural additions.

Yes, even though I saw numerous videos where they were welding up various reinforcements to this brake, I was leary of doing most of them for the fear of warping. My mistake was not tacking and welding in the right order and I should have done half as much welding as I did and it would have been just as strong with way less chance of warping.

Son ""whatcha doing dad?"

Dad "oh I'm just fixing this metal brake making it better."

Son the next day "did you finish fixing your metal brake Dad?"

Dad " Yup its over there in the scrap iron pile"

 

[Susquatch]

Yes, even though I saw numerous videos where they were welding up various reinforcements to this brake, I was leary of doing most of them for the fear of warping. My mistake was not tacking and welding in the right order and I should have done half as much welding as I did and it would have been just as strong with way less chance of warping.

Son ""whatcha doing dad?"

Dad "oh I'm just fixing this metal brake making it better."

Son the next day "did you finish fixing your metal brake Dad?"

Dad " Yup its over there in the scrap iron pile"

I think it was doomed to hit the scrap pile the minute you hauled out the welder. Maybe it can be done in the right sequence, but since it's one side only, I am not on board to even try. Of course that opinion is heavily skewed by my very poor welding skills.

My neighbour (who welds half decent) is always laughing at all my fasteners and I laugh at his Welding.

I guess both have their place.

 

[cuslog]

Just a thought: Ever looked into "flame straightening" - there's a few youtube vid's on this. Actually a pretty interesting process. I've played around with it some - had some success, some not so much - burned up some oxy-acetylene too.
Keith Fenner's got a pretty good video of prop shaft flame straightening.

 

[DPittman]

Well I cut through all 3 of the gusset braces I welded in and was hoping the angle would pop back to original straightness but not surprisingly it did not. There was some improvement but it is still unusable as is.
It is hard to show in pictures but you might see in the circled area how the meeting corners are not straight.

You can also see that it was probably excessive to weld as much as

I did along the gusset and on only one side of the gusset.

 

[DPittman]

Just a thought: Ever looked into "flame straightening" - there's a few youtube vid's on this. Actually a pretty interesting process. I've played around with it some - had some success, some not so much - burned up some oxy-acetylene too.
Keith Fenner's got a pretty good video of prop shaft flame straightening.

Hmnn I'll have to look into that. I probably should cut my losses right now by giving up on this but the learning is valuable. I'm glad this wasn't a high priced thing or something that was critical to my livelihood.

 

[YotaBota]

Rather than gussets, what about a new heavier piece of angle and a flat bar to box in the angle? Careful stitch welding the flat bar in to mitigate twisting should be less prone to warping than gussets. In 24" you'd probably only need a 1/2" stitch every 4" or so to have a more rigid piece.

 

[Susquatch]

Rather than gussets, what about a new heavier piece of angle and a flat bar to box in the angle? Careful stitch welding the flat bar in to mitigate twisting should be less prone to warping than gussets. In 24" you'd probably only need a 1/2" stitch every 4" or so to have a more rigid piece.

Bolt it, don't weld it! A flush cone head machine screw every 4" (or even 6") would be just fine with no distortion.

 

[DPittman]

Bolt it, don't weld it! A flush cone head machine screw every 4" (or even 6") would be just fine with no distortion.

Well the bending angle is only .225' thick so there isn't a lot of material to work with countersunk screws.

I actually have it darn near back to normal with some trial and error flame straightening, thanks to @cuslog suggestion. Initially I had it looking more like a big wavy parallel but I finally got it figured out mostly.

It still has about .030" warp in the middle and I suppose that probably could be ground out and it would be useable as is now, but I think I want to push my luck and see if I can get it better.

@YotaBota yes I could/should have used that method to begin with.

I'm going to attempt to weld the cut gussets back together and "think" I might be okay as the heat will be on the gusset now and not on the angle. I will also be a bit more scrupulous in my welding.

The one picture shows the 4 heated spots I did on the back side along with the original gussets spots. I also did some heating spots on the opposite angle not shown.

 

[DPittman]

Well I got the last .030" warp out. I had my cousin with a hydraulic press straighten the last bit out. I dare say it might even be straighter now than when the thing was new.

 

[Susquatch]

I'm glad it is working out for you. I'd hate to see it become scrap - especially after so much work!

Not to push the issue, but rather for closure -

Well the bending angle is only .225' thick so there isn't a lot of material to work with countersunk screws.

Actually, 0.225" is plenty of room for a countersunk cone screw. I do that all the time. The hole is just cut at 82 degrees till the head of the screw is flush or slightly below the working surface. Maybe my nomenclature is misleading. Here is the screw I'm talking about.

I find that using screws like the ones shown above avoids the distortion problems that welding causes, they require zero space on the working surface, and they can be extremely strong. I also find them to be superior to small weld beads at the same spacing. Of course, Continuous Welding is stronger than screws but then you get even more distortion.

Anyway, as I said, if Welding is working out then nothing is wrong with that! Maybe next time.

 

[Susquatch]

Well I got the last .030" warp out. I had my cousin with a hydraulic press straighten the last bit out. I dare say it might even be straighter now than when the thing was new. View attachment 18570

Woah! That is some hydraulic press! Gotta be well over 50 tons. 100? Looks like an 8 or 10" ram. At 3000 psi, that thing could be 150,000 to 250,000 pounds!

 

[YotaBota]

If you haven't welded the gussets up yet make sure you wedge them open before welding, the welding will close the gap as it cools warping things again.

 

[Susquatch]

If you haven't welded the gussets up yet make sure you wedge them open before welding, the welding will close the gap as it cools warping things again.

Or bolt them together with plates so nothing moves ....... LOL!

Can you tell how much I love welding yet?