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Thread: bending 1-inch stainless tubing

  1. #1
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    Default bending 1-inch stainless tubing

    I need to make a stern pulpit and I'm reeling at the prices charged by my two local metal shops for doing this. I don't need anything super fancy, but it will have to support a couple of 60 watt solar panels at some point. Two 90-deg bends plus some 1" stainless hardware from West Marine or Defender and I'll have what I need.... I think.

    I'm thinking about making a table-top plywood jig that has about a 4-inch radius cut into it, and screwing it to the table. Then I lay a length of tubing in there..then grab ahold of it and haul like he11, but not sure if that's going to do the trick. I see lots of video's of neato pipe benders on YouTube, but I don't think I want to buy one of those.

    I DO have a 2-ton hydraulic car jack lying around. Hmmmm. I supposed I could knock together a DIY version of the Harbor Freight hydraulic bender, maybe?

    Thoughts? Suggestions?
    CLC Skerry = "Vingilothiel"

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    Default Re: bending 1-inch stainless tubing

    In the old days when I was an apprentice, the bow handrails were bent on the shop floor. This was a 65’ motoryacht, but it had a pretty full deck curve.
    We picked up a pattern for the curve, and then filled the tubing with sand and then bent it to the pattern.
    Sorry, but that is all I can remember...it was back in the early 70’s

  3. #3
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    Default Re: bending 1-inch stainless tubing

    Oh,and we plugged the ends of the tubing to keep the sand in place while bending.

    The sand kept the tube from collapsing under the stress,of bending. Still required careful application of bending power, but not amsp cialized machine.

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    Default

    I bought (or reused) pre made curves and welded them in place.

    Sent from my SM-G930F using Tapatalk

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    Default Re: bending 1-inch stainless tubing

    Quote Originally Posted by Snow Pea View Post
    I bought (or reused) pre made curves and welded them in place.

    Sent from my SM-G930F using Tapatalk
    Well son of a gun. I didn't know you could buy pre-made bent stainless tubing. $18 each. pfffft. THANKS!
    CLC Skerry = "Vingilothiel"

  6. #6
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    Default Re: bending 1-inch stainless tubing

    Electricians might have benders for rigid conduit.
    R
    Sleep with one eye open.

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    Default Re: bending 1-inch stainless tubing

    Alan, if you have a muffler / exhaust system shop near you, they may do it for a few bucks or so, they have lots of sophisticated bending
    machinery .... just a suggestion

    Rick

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    Default Re: bending 1-inch stainless tubing

    I don't think that conduit benders can handle 1-inch stainless tubing. aluminum...yes, for sure. Maybe they can even do 7/8ths stainless, but I have my doubts about 1-inch.
    CLC Skerry = "Vingilothiel"

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    Default Re: bending 1-inch stainless tubing

    Glad you found ready made bent tubing, but did it have to be curved at all? 90, 60, 45 and 30 degree angles can be rigged up with fittings and straight sections.
    "... and the great shroud of the sea rolled on as it rolled five thousand years ago."

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    Default Re: bending 1-inch stainless tubing

    Quote Originally Posted by rbgarr View Post
    Glad you found ready made bent tubing, but did it have to be curved at all? 90, 60, 45 and 30 degree angles can be rigged up with fittings and straight sections.
    Certainly some of what I'll be building will be made out of "parts". There were just two bends that I thought would work beetter, "bent" instead of being put together by 90 deg fittings.
    CLC Skerry = "Vingilothiel"

  11. #11
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    Default Re: bending 1-inch stainless tubing

    Quote Originally Posted by Paul Schweiss View Post
    In the old days when I was an apprentice, the bow handrails were bent on the shop floor. This was a 65’ motoryacht, but it had a pretty full deck curve.
    We picked up a pattern for the curve, and then filled the tubing with sand and then bent it to the pattern.
    Sorry, but that is all I can remember...it was back in the early 70’s
    That's the way I was taught, pack with sand, plug or weld the ends but drill a hole to let out the steam !! Heat and bend. This Youtube of a bloke bending an exhaust pipe gives the idea. The sand is rammed in hard and as dry as possible .



    This one too. https://www.youtube.com/watch?v=mawebpskaWs
    Last edited by PeterSibley; 10-28-2017 at 03:09 AM.
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    Default Re: bending 1-inch stainless tubing

    On a motorcycle theme, handlebars are a good source of curves... breakers yard stuff don't buy new. most jap and Brit bikes are 7/8" but Harleys are often stainless and 1"
    When you come to a fork in the road , take it.


    Smarter than the average bear, Booboo

  13. #13
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    Default Re: bending 1-inch stainless tubing

    Sleep with one eye open.

  14. #14
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    Default Re: bending 1-inch stainless tubing

    I think that motorbike parts and exhausts might be too thin wall to be safe for welded guardrails.
    It really is quite difficult to build an ugly wooden boat.

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    Default Re: bending 1-inch stainless tubing

    +1 on fill tube with dry sand . . . plugging ends of tube to hold sand can as simple as masking tape.
    .
    .
    +1 on plywood form to bend to . . . challenges are (a) solid mounting place for the plywood form (b) long enough tube to be able to have a lever arms either side of the curve to hold&pull-push. (c) plywood form having a hollow rather than a flat face to keep the tube from slipping off is a big plus.
    .
    Notes: (i) Any time one creates a short bent tube without fancy roller dies you must usually have fairly long waste/sacrificial bits on either side of the curved part. (2) for solid mounting place, a trailer hitch receiver on a vehicle is solid/strong and portable starting point. (3) a piece of slightly larger pipe that will fit over the 1" CRS tube to use as a pull-push handle extension, minimizes the wasted 1" tubing.
    Last edited by George Ray; 10-28-2017 at 10:55 AM.
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    Default Re: bending 1-inch stainless tubing

    just been checking for what it's worth...22mm+, 7/8 handlebar, 2.6mm wall.
    1", 25.6 mm stainless HD handlebar 1.8 - 2mm wall.
    guard rail on 5.5 metre runabout, 20mm stainless, wall thickness 2mm....
    seems smaller the tube dia. the thicker the material.....still I think a 300kg bike with potential for say 200kg of rider and pillion standing on the brakes at 100kph Id go for 'that isn't going to bend'
    When you come to a fork in the road , take it.


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    Default Re: bending 1-inch stainless tubing

    Quote Originally Posted by jonboy View Post
    I think a 300kg bike with potential for say 200kg of rider and pillion standing on the brakes at 100kph Id go for 'that isn't going to bend'
    A bit different from being thrown against it by a big wave with drowning on the other side. Still it isn't going to be me.
    It really is quite difficult to build an ugly wooden boat.

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    Default Re: bending 1-inch stainless tubing

    West Marine's s.s. railing tubing is .049 wall thickness in 304 alloy. This is 18 gauge, BTW.

    https://www.westmarine.com/buy/west-...24_722_003_002

    90 degree bent, 304 stainless steel, .05 wall thickness - $15 a little bit of welding and you're on your way.

    http://www.anfittingsdirect.com/exhaust-pipe/stainless-steel-pipe-and-bends/mandrel-bent-ss-p-844.html


    Last edited by Alan H; 10-28-2017 at 02:24 PM.
    CLC Skerry = "Vingilothiel"

  19. #19
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    Default Re: bending 1-inch stainless tubing

    You can even get 90 degree 304 stainless mandrel bends in 1-inch s.s. on Amazon.com though these are 16 gauge, so a bit thicker. Probably makes no difference if you are welding them.

    https://www.amazon.com/Degree-Buttwe...re-bullets-btf
    CLC Skerry = "Vingilothiel"

  20. #20
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    Default Re: bending 1-inch stainless tubing

    I have bought from these folks several times, and will again.
    (they have either 316 or 304 ss mandrel bends in several gauges and diameters)

    http://www.mandrelbends.com/mandrel-bends.html

  21. #21
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    Default Re: bending 1-inch stainless tubing

    A friend recently rebuilt his railing and bought prebent curves but the way it used to be done "once upon a time'', say 50 years ago was the motorcycle exhaust bend method.
    '' You ain't gonna learn what you don't want to know. ''
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    Default Re: bending 1-inch stainless tubing

    A stainless steel magician told me to fill the pipe with sand, bend her around an mdf shape with a pipe slightly bigger. Suppose you have to keep ends pipe closed. Seemed simple . Frank van Zoest

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    Default Re: bending 1-inch stainless tubing

    If you plan to weld the tubing or bend it with heat, use the low carbon grades. 304L or 316L. The heat can cause the stainless to corrode.

    A steel mandrel will leave bits of steel embedded in the stainless tubing that will cause it to rust. You will need to passivate. Plywood, Nylon or stainless tooling is better.

    https://www.rolledalloys.com/technic...sensitization-
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    Default Re: bending 1-inch stainless tubing

    Some pipe and tubing benders, who make Brass horns, pack the tubing with rosin powder. It makes for a smoother bend.
    jay

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    Default Re: bending 1-inch stainless tubing

    Quote Originally Posted by Jay Greer View Post
    Some pipe and tubing benders, who make Brass horns, pack the tubing with rosin powder. It makes for a smoother bend.
    jay
    I tried to lookup something about using rosin powder and found some old references to filling tubes with molten pitch or a mix of pitch and rosin. Some used just rosin. Springs, table salt and frozen soapy water were also suggested here and there.
    tube bending.jpg
    A more expensive, generally toxic, but very effective material is Cerrobend. There are a number of versions with melting points between 117 and 200 F. They usually contain lead and cadmium.
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    Default Re: bending 1-inch stainless tubing

    Interesting Dave. I always thought it was powdered rosin. But, I do wonder how they would get the melted pitch out of the insides of the Tubas and Trombones then?
    Jay

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    Default Re: bending 1-inch stainless tubing

    Quote Originally Posted by Jay Greer View Post
    Interesting Dave. I always thought it was powdered rosin. But, I do wonder how they would get the melted pitch out of the insides of the Tubas and Trombones then?
    Jay
    There is a good pun in there somewhere about the instrument builders having perfect pitch, thus making it easier to work with.

    What I did read was that they melted the pitch, rosin, or mixture in an oven and poured it out. The remaining residue was removed with a solvent. When you use the low melting alloys, the first step is to coat the tube with oil to prevent soldering or sticking. They also said to avoid using a torch because local overheating caused a long list of problems depending on materials involved.
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    Default Re: bending 1-inch stainless tubing

    I thought brass instruments were shaped using hydraulic fluid pressure inside molds , hydroforming .
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    Default Re: bending 1-inch stainless tubing

    Slide a piece of next size down of solid aluminum or copper inside the stainless and proceed to bend. The inside radius will have some crimps as the radius is reduced there but the balance of the tube will be perfect.

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    Default Re: bending 1-inch stainless tubing

    Solid if you can find it

  31. #31
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    Default Re: bending 1-inch stainless tubing

    Scrap yards are your friend

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    Default Re: bending 1-inch stainless tubing

    Quote Originally Posted by PeterSibley View Post
    I thought brass instruments were shaped using hydraulic fluid pressure inside molds , hydroforming .
    You would think that you could find some decent pictures or videos to illustrate the hydroforming process used on musical instruments. There are plenty of sites that say it is done, but very little detail. Tube hydroforming seems to be used for precise forming of sax necks, and some bell preforms, but there is squat for detail. Link1 Link 2 There is one tuba video that does tube hydroforming in a hydraulic blowout press https://www.youtube.com/watch?v=1kfdxvNXIyk about 3:30

    Spinning is common enough, but seems to be more of a final finishing process. Link 4 trumpet making has lots of bending and spinning detail. Link 3
    link 4
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