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Author Topic:   Advice Sought on Straightening Tubing

Tom Hemphill posted 01-30-2015 06:30 PM ET (US)
One of my side railings and the mast for the stern mounted white light on my classic 16-foot Whaler have developed unwanted curves over the years. I would appreciate suggestions on how to straighten these items.
jimh posted 01-30-2015 06:54 PM ET (US)
My first guess is perhaps something like an electrical conduit pipe bender. See
http:/ / www. homedepot. com/ b/ Electrical-Electrical-Tools-Accessories -Electrical-Tools-Conduit-Benders-Sizers/ N-5yc1vZbmcy
The above, coupled with skill in its use, might be able to help.
Jefecinco posted 01-30-2015 07:57 PM ET (US)
Perhaps you could fabricate a die by screwing two 2" x 4" planks to a piece of plywood spaced the same distance apart as the diameter of the tubing you wish to straiten.
You could then heat the tubing along its length and while it is hot and slightly malleable you could force it between the 2 X 4's with a rubber headed mallet.
Hopefully, when the tubing cooled it would have set in the same attitude as it was in the die.
If the tubing wall thickness is minimal the heating may be accomplished by a standard homeowner's butane or propane torch. I've seen this done with solid round steel stock using a oxyacetylene torch and a steel die and some tools for added mechanical advantage.
Jerry Townsend posted 01-31-2015 01:38 PM ET (US)
Be careful with heat - as too much heat (which depends on the specific material) can anneal the tubing, decreasing the yield strength thereby making it easier to bend, and can discolor the tubing. But, the yield strength can be restored by proper heat treatment.
How was the tubing bent? The bending in your case was done with the tubing cold - and the "unbending" might be possible via applying a similar load, but larger, and opposite to the load applied in bending the tubing. --- Jerry/Idaho
Jefecinco posted 01-31-2015 07:08 PM ET (US)
Unbending cold thin wall tubing can be a disaster if not done very carefully. Kinks or creases are not inevitable but frequently occur. If the tubing under discussion has bent due to long term use rather than a sudden loading and if the bends are quite gradual unbending cold may work out. I would not attempt it. The least risky approach is with the application of heat. It should not be necessary to heat the tubing to a reddish tint before carefully forcing it into a die. The blueish color often seen can be rubbed out with a fine abrasive.
I've bent a lot of copper tubing and conduit using tubing benders but never to straighten a tube already bent. I have used a bender to decrease the radius of a bend that was bent to too tight a radius.
Stainless steel tubing is fairly brittle. Be careful and good luck,
contender posted 01-31-2015 07:38 PM ET (US)
Are you are stating you have hit the dock over the years to customize your railing?... Trying to straighten a round object is useless it will never happen, you will come close but never right, best to replace...good luck either way
Binkster posted 02-01-2015 11:16 AM ET (US)
Contender is right, it will never happen. Don't waste your time. Get a new rail. BTW if you're bending a new piece of stainless rail with a pipe bender such as jimh mentions you need to fill the rail with play sand first otherwise you will kink it. Its not easy to bend and impossible to straighten.
Tom Hemphill posted 02-01-2015 03:53 PM ET (US)

quote:
Are you are stating you have hit the dock over the years to customize your railing?

Ha, you're on to me! Actually it only took one encounter with a piling during a difficult docking maneuver; my rail mounted rod holder took the hit. You (and Binkster) are right, replacement is the only way to get it right. My stern light mast is wavy from abuse by previous owners. It isn't very bad, so I think I'll just live with it. Thanks to everyone for your suggestions!
padrefigure posted 02-03-2015 09:11 AM ET (US)
I don't know how you would do it on a small scale, but round lighting poles start out as a flat sheet cut into a trapezoid. The edges are then pulled together and seam welded. The result is round tube in cross section, but more like a corkscrew over the length. The shaft is then rolled to straighten and perfect the cross section. This takes a really big piece of equipment and lots of hydraulic power. The result is a stronger, straight pole. If you could figure out how to roll the bent section of pipe, maybe you could get the same results.
Jefecinco posted 02-03-2015 07:03 PM ET (US)
Metal lathes can be used to straighten round stock or at least to determine when they are straight and if not where they are not straight so that they may be straightened. Bad sentence but understandable, I think.
deepwater posted 02-12-2015 12:46 AM ET (US)
Fill the tube with very fine sand and tightly plug the ends,,useing a soft rubber mallet tap firmly all around the bent area,,as it straightens you may have to add sand to keep it as solid yet moveable as pos,,you can try several types of mallets from soft to hard to lead
elvis posted 02-12-2015 12:50 PM ET (US)
Wonder if tightly packing inside of tube with sand would keep it from collapsing when being bent?
Jerry Townsend posted 02-12-2015 05:14 PM ET (US)
It will.
deepwater posted 02-14-2015 07:22 PM ET (US)
I is the same concept used to make wrinkle free bends by using a moving mandrel but with more dust.
Binkster posted 02-18-2015 03:01 PM ET (US)
Has anyone who has reswponded to this thread actually straightened bent railings on their Whaler by the methods they recomended, or is it only conjecture. I think Tom has set himself up as a pioneer in rail straightening if he trys all the above methods.
jimh posted 02-20-2015 02:25 PM ET (US)
Since the length of the bent sections is probably short, cutting them out and replacing them is probably the easiest repair--if you can weld them back in place. That is particularly true for the white all-round light mast, which can probably replaced in its entirety with a new piece. I have seen some presentations of tube factory machines which employ big rollers to true-up pieces of tubing, but that is not something that could be implemented as a home repair.
contender posted 02-21-2015 05:05 PM ET (US)
I agree with bink. By the time you remove a section of tubing to have it straighten, it will cost you a minimum of $50 at the machine shop. I would consider this a waste and you are just spinning your wheels--replace is the best option if you want to to be correct. Or remove the entire railing.
deepwater posted 02-23-2015 11:15 AM ET (US)
I don't think you can get at the inside of a side rail,,the anchor lite would be the same as a copper pipe I had a bend in,,the sand worked just great,,as the bend was lightly hammered out I had to add sand,, I would also suggest if you want the tube really straight,,after hammering the bend out ,, roll it between some wide pieces of wood,,,almost like pie dough,, but with flat wood ^@^
deepwater posted 02-23-2015 11:20 AM ET (US)
If its just some slight curves,,A thick walled pipe with a close ID of the OD of your tube can be cut in 1/2 and worked over the curved sections using screw clamps and alittle heat
Binkster posted 02-23-2015 01:10 PM ET (US)
Again, forget the hypothetical conjecture. Go this route
http://www.specialtymarine.com/ SIDE-RAILS-CLASSIC-15-BOSTON-WHALER-OEM-STYLE-p102.html
rich

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Author	Topic: Advice Sought on Straightening Tubing
Tom Hemphill	posted 01-30-2015 06:30 PM ET (US) One of my side railings and the mast for the stern mounted white light on my classic 16-foot Whaler have developed unwanted curves over the years. I would appreciate suggestions on how to straighten these items.
jimh	posted 01-30-2015 06:54 PM ET (US) My first guess is perhaps something like an electrical conduit pipe bender. See http:/ / www. homedepot. com/ b/ Electrical-Electrical-Tools-Accessories -Electrical-Tools-Conduit-Benders-Sizers/ N-5yc1vZbmcy The above, coupled with skill in its use, might be able to help.
Jefecinco	posted 01-30-2015 07:57 PM ET (US) Perhaps you could fabricate a die by screwing two 2" x 4" planks to a piece of plywood spaced the same distance apart as the diameter of the tubing you wish to straiten. You could then heat the tubing along its length and while it is hot and slightly malleable you could force it between the 2 X 4's with a rubber headed mallet. Hopefully, when the tubing cooled it would have set in the same attitude as it was in the die. If the tubing wall thickness is minimal the heating may be accomplished by a standard homeowner's butane or propane torch. I've seen this done with solid round steel stock using a oxyacetylene torch and a steel die and some tools for added mechanical advantage.
Jerry Townsend	posted 01-31-2015 01:38 PM ET (US) Be careful with heat - as too much heat (which depends on the specific material) can anneal the tubing, decreasing the yield strength thereby making it easier to bend, and can discolor the tubing. But, the yield strength can be restored by proper heat treatment. How was the tubing bent? The bending in your case was done with the tubing cold - and the "unbending" might be possible via applying a similar load, but larger, and opposite to the load applied in bending the tubing. --- Jerry/Idaho
Jefecinco	posted 01-31-2015 07:08 PM ET (US) Unbending cold thin wall tubing can be a disaster if not done very carefully. Kinks or creases are not inevitable but frequently occur. If the tubing under discussion has bent due to long term use rather than a sudden loading and if the bends are quite gradual unbending cold may work out. I would not attempt it. The least risky approach is with the application of heat. It should not be necessary to heat the tubing to a reddish tint before carefully forcing it into a die. The blueish color often seen can be rubbed out with a fine abrasive. I've bent a lot of copper tubing and conduit using tubing benders but never to straighten a tube already bent. I have used a bender to decrease the radius of a bend that was bent to too tight a radius. Stainless steel tubing is fairly brittle. Be careful and good luck,
contender	posted 01-31-2015 07:38 PM ET (US) Are you are stating you have hit the dock over the years to customize your railing?... Trying to straighten a round object is useless it will never happen, you will come close but never right, best to replace...good luck either way
Binkster	posted 02-01-2015 11:16 AM ET (US) Contender is right, it will never happen. Don't waste your time. Get a new rail. BTW if you're bending a new piece of stainless rail with a pipe bender such as jimh mentions you need to fill the rail with play sand first otherwise you will kink it. Its not easy to bend and impossible to straighten.
Tom Hemphill	posted 02-01-2015 03:53 PM ET (US) quote: Are you are stating you have hit the dock over the years to customize your railing? Ha, you're on to me! Actually it only took one encounter with a piling during a difficult docking maneuver; my rail mounted rod holder took the hit. You (and Binkster) are right, replacement is the only way to get it right. My stern light mast is wavy from abuse by previous owners. It isn't very bad, so I think I'll just live with it. Thanks to everyone for your suggestions!
padrefigure	posted 02-03-2015 09:11 AM ET (US) I don't know how you would do it on a small scale, but round lighting poles start out as a flat sheet cut into a trapezoid. The edges are then pulled together and seam welded. The result is round tube in cross section, but more like a corkscrew over the length. The shaft is then rolled to straighten and perfect the cross section. This takes a really big piece of equipment and lots of hydraulic power. The result is a stronger, straight pole. If you could figure out how to roll the bent section of pipe, maybe you could get the same results.
Jefecinco	posted 02-03-2015 07:03 PM ET (US) Metal lathes can be used to straighten round stock or at least to determine when they are straight and if not where they are not straight so that they may be straightened. Bad sentence but understandable, I think.
deepwater	posted 02-12-2015 12:46 AM ET (US) Fill the tube with very fine sand and tightly plug the ends,,useing a soft rubber mallet tap firmly all around the bent area,,as it straightens you may have to add sand to keep it as solid yet moveable as pos,,you can try several types of mallets from soft to hard to lead
elvis	posted 02-12-2015 12:50 PM ET (US) Wonder if tightly packing inside of tube with sand would keep it from collapsing when being bent?
Jerry Townsend	posted 02-12-2015 05:14 PM ET (US) It will.
deepwater	posted 02-14-2015 07:22 PM ET (US) I is the same concept used to make wrinkle free bends by using a moving mandrel but with more dust.
Binkster	posted 02-18-2015 03:01 PM ET (US) Has anyone who has reswponded to this thread actually straightened bent railings on their Whaler by the methods they recomended, or is it only conjecture. I think Tom has set himself up as a pioneer in rail straightening if he trys all the above methods.
jimh	posted 02-20-2015 02:25 PM ET (US) Since the length of the bent sections is probably short, cutting them out and replacing them is probably the easiest repair--if you can weld them back in place. That is particularly true for the white all-round light mast, which can probably replaced in its entirety with a new piece. I have seen some presentations of tube factory machines which employ big rollers to true-up pieces of tubing, but that is not something that could be implemented as a home repair.
contender	posted 02-21-2015 05:05 PM ET (US) I agree with bink. By the time you remove a section of tubing to have it straighten, it will cost you a minimum of $50 at the machine shop. I would consider this a waste and you are just spinning your wheels--replace is the best option if you want to to be correct. Or remove the entire railing.
deepwater	posted 02-23-2015 11:15 AM ET (US) I don't think you can get at the inside of a side rail,,the anchor lite would be the same as a copper pipe I had a bend in,,the sand worked just great,,as the bend was lightly hammered out I had to add sand,, I would also suggest if you want the tube really straight,,after hammering the bend out ,, roll it between some wide pieces of wood,,,almost like pie dough,, but with flat wood ^@^
deepwater	posted 02-23-2015 11:20 AM ET (US) If its just some slight curves,,A thick walled pipe with a close ID of the OD of your tube can be cut in 1/2 and worked over the curved sections using screw clamps and alittle heat
Binkster	posted 02-23-2015 01:10 PM ET (US) Again, forget the hypothetical conjecture. Go this route http://www.specialtymarine.com/ SIDE-RAILS-CLASSIC-15-BOSTON-WHALER-OEM-STYLE-p102.html rich