Straightening a Gate

[Rgillard]

Hi Guys,

Im in the process of building a roller gate. Its 6 ft high and 18ft wide. I am using 4 x 2 section for the main perimeter and 2 X 2 for the uprights in the centre. My problem is that one of the pieces of 4 X 2 is slightly warped/twisted (was like this when the steel was delivered) Wall is only 5/16ths , and the whole gate is twisted. I am wondering what would be the best technique to try and straighten the bar. I have an oxy propane torch for heat. the final gate will have Palisade fencing (not sure if you have that in the US) bolted to the front. I notice over this length that there is a lot of flexibility when the gate is lying on the ground. Does any one have any kind words of wisdom for me...


Regards,

Ronan

 

[2manyrocks]

I couldn't get a piece of steel straightened on a trailer last week --and finally cut it out. Wish I had cut it out to start with.

But I'd ask that question on Weld Talk Message Boards - Powered by vBulletin to see what they suggest.

 

[BTDT]

Welcome to the forum. My guess is (or if it was mine), try to put something diagonally from top corner to bottom corner with a turnbuckle to tighten and pull back into position. Good luck. Not really that noticeable in the picture, and I bet you can't tell it from the front (as you would pull up to it).

 

[Rgillard]

Yeah Its not noticeable from the front but its that it might not run straight on the guide rail that worries me. I am going to try clamping an RSJ either side of the bent bar. That will straighten the bar for me. If i then heat the area that is bent will the steel cool and stay straight once the RSJ's have been removed. If that doesnt work I will cut the piece out and start again. prob should have done that to start with but Its good to be learning how to use the gas for heating

Ron

 

[srjones]

Yeah, that's warped alright....

The welding forums may have better ideas, but if it was me, I'd take a recipicating saw and cut through the joints on each corner, leaving enough steel to keep it together, but just enough remaining steel that it would bend into the shape you want.

Then, weight down all four corners with concrete blocks and weld it back together.

Remember, just the process of welding may cause warpage with the expansion/contraction so you might want to read up on that. I still haven't figured that one out yet, other than to weld corner to corner and check the angles/distances frequently.

BTW, try to think ahead and cut in the direction where you want the peice to bend. For example, imagine the letter "V" and you were trying to flatten it out into "--" You'd cut through the top, but leave the bottom intact. Otherwise, the partial cut would close in on itself.

Good luck

 

[RobJ]

BTW, try to think ahead and cut in the direction where you want the peice to bend. For example, imagine the letter "V" and you were trying to flatten it out into "--" You'd cut through the top, but leave the bottom intact. Otherwise, the partial cut would close in on itself.

Good tip because when metal bends it stretches and now it's longer on one side. But instead of a bend you probably just have a bow. You have to go to multiple places because there might not be a single apex. You might not ever get it perfectly straight, but hopefully good enough to ride the rail.

I'm a woodworker and there is the same problem with wood. If I make a large (long/tall) raised panel door and the next day it's warped, I just chunk it and start over.

Good Luck

 

[Farmerford]

Ronan:

Use an old car bodyman's trick to shrink metal. On the outside of the bend, and about one-half way down each side from the outside, heat the tube red hot. If your torch is large enough you might get a strip 1/2 to 1 inch wide red hot. When the tube wall cools it will shrink and put a counter bend in the tube. You will be surprised how much the shrinkage bends the tube. If it is not bent enough, do it again on each side of the first place, perhaps a couple of feet away if the bend is gentle.

Perhaps quicker, but not very attractive, just weld a bead where you would have heated with the torch. The weld will heat the underlying metal and the weld metal itself will be molten, so when it cools it will pull the tube back toward the weld.

If your material is mild steel, it will not have enough carbon to harden even though you cool it pretty fast. When I have been in a real hurry I have doused the heated area with water, that not only cools it faster, it also seems to increase the shrinkage.

 

[6sunset6]

What Farmerford said. I completly mangled a door on the cab of a MF30backhoe twice. Left it open and hit a tree. It sticks past the tire. Was stretched . Heated and cooled with a wet rag. took the wrinkles out of a hood like that also. But it does work sort of amazing.

 

[srjones]

I'm a woodworker and there is the same problem with wood.

I sure wish it worked like that for wood. I also wished they made a tennon stretcher, but they don't

 

[RobJ]

I sure wish it worked like that for wood. I also wished they made a tennon stretcher, but they don't

I should correct myself and say with wood I haven't heard of anything that REALLY works. Some try wet, laying flat...nothing seems to work, at least for me and my WW friends.