Putting a slight bend in 1" SS Tubing

[coopec43]

Mandrel and Wiper Die Selection

https://www.omni-x.com/us/table-for-...and-wiper-dies

[singlespeed]

Fill the tubes with sand and cap. The caps do not have to be a tight fit, but but to make certain the sand doesn't fall out when transporting to the "mandrel". Find two firmly anchored poles, your "mandrel". Where you want the center of the bend is where the tubing should contact the pole that is closest to the end where you will be applying pressure. Apply pressure to the end. If your physical strength isn't enough, use a come along or even a vehicle to get the bend you want. For identical bends, bind the two poles together and pull as one. Have to thank Hobie Alter (Hobie Cat) for this tip. Bent my mast in the surf and he showed me how to straighten it. It did require the two of us, a pair of power poles, my car and a whole lot of sand, but I raced with that mast for several years with no issues. Used the same technique to build a new bimini.

[drdoyle]

Local machine shop. A special hydraulic bender and spindle are required to prevent kinking. The pipe is drawn around a die that matches the OD of the pipe. There is an outside matching roller to pull the pipe around the center die. Center die spindles come in different radius diameters and different pipe sizes.

[Montanan]

Stepping back:

Why do you need to have the platform bent to mount a solar panel?

Most PV panels do not have a bend. It would seem that you then have to configure a bracket on the mount to offset the arch so as to provide for attachment of the panel.

What is the specific purpose of having a gentle arc?

[rossdv8]

Take it along to an automotive exhaust shop and see if they can fit it into one of their presses.

[betwys1]

Originally Posted by Ryban

I'm fabricating a structure that will attach to our dodger to mount solar (see https://www.geminiproducts.net/how-t...-7-easy-steps/).

I need to put a small bend in the center of two 5-6' long stainless 1" OD tubes. I'm not certain what angle will be needed, but probably on the order of 10-20 degrees with any suitable radius.

Options I'm considering:

• Manual mandrel bender -- kind of expensive for just making 2 bends.
• Joining two pieces with 7/8" tubing pre-bent -- there's a 7/8" hydraulic bender that's only $70. Won't have to ship long sections.
• Make a wooden form and use a lot of leverage.
• Shop it out to a local fab shop.

The type with the central hydraulic jack pusher is easiest to use and Definitely easiest to kink piping.

Either iterate the bend at 1 inch intervals or for superior bends use SHARP sand to fill the pipe. The end caps need to withstand no pressure because sharp sand links so duct tape will do the job. The dies need to have accurate one inch diam profiles.

[Sailshabby]

Machine shop. Won’t be that much and it’ll look better.

[Ryban]

Originally Posted by Montanan

Stepping back:

Why do you need to have the platform bent to mount a solar panel?

Most PV panels do not have a bend. It would seem that you then have to configure a bracket on the mount to offset the arch so as to provide for attachment of the panel.

What is the specific purpose of having a gentle arc?

Not sure if you saw the photo in the original post, but basically there will be a single bend in the middle to accommodate the arc of the dodger. That will leave 2 straight segments on either side of the bend, and its on these straight segments that the panels will mount.

I'll probably end up just taking this to a shop to do, but I did find these 2 bronze rollers that would be almost perfect to use to bend against.

[Pete7]

Originally Posted by Montanan

Stepping back:

Why do you need to have the platform bent to mount a solar panel?

Most PV panels do not have a bend. It would seem that you then have to configure a bracket on the mount to offset the arch so as to provide for attachment of the panel.

What is the specific purpose of having a gentle arc?

Clearance over the top of a bimini or cockpit canopy (miss labelled as a dodger above).

However, that will mean that each panel will have different levels of solar at any particular point during the day. May not matter, but if maximum performance is required then separate MPPTs needed which we covered in another thread.

[Montanan]

Originally Posted by Ryban

Not sure if you saw the photo in the original post, but basically there will be a single bend in the middle to accommodate the arc of the dodger. That will leave 2 straight segments on either side of the bend, and its on these straight segments that the panels will mount.

I'll probably end up just taking this to a shop to do, but I did find these 2 bronze rollers that would be almost perfect to use to bend against.

Ah, I was mistakenly thinking of a continuous arch onto which the solar panels would be mounted and not a simple bend in the middle with two not bent portions.

But still don't see a need to bend to conform with the bimini's arch shape; functionally not of consequence to have a flat surface over an underlying radius surface, so long as there is clearance.

Bon voyages.

[Cheechako]

Originally Posted by Ryban

I'm fabricating a structure that will attach to our dodger to mount solar (see https://www.geminiproducts.net/how-t...-7-easy-steps/).

I need to put a small bend in the center of two 5-6' long stainless 1" OD tubes. I'm not certain what angle will be needed, but probably on the order of 10-20 degrees with any suitable radius.

Options I'm considering:

• Manual mandrel bender -- kind of expensive for just making 2 bends.
• Joining two pieces with 7/8" tubing pre-bent -- there's a 7/8" hydraulic bender that's only $70. Won't have to ship long sections.
• Make a wooden form and use a lot of leverage.
• Shop it out to a local fab shop.

The bend in that Gemini link is not a small bend. Looks like nearly 90 degrees.
If you are talking the minor bend in your picture at center, go rent a conduit hand bender and it'll work. No mandrel or packing needed. Easy peasy

[Ryban]

Originally Posted by Cheechako

The bend in that Gemini link is not a small bend. Looks like nearly 90 degrees.
If you are talking the minor bend in your picture at center, go rent a conduit hand bender and it'll work. No mandrel or packing needed. Easy peasy

I think you're looking at the wrong bend. I'm just talking about the bend at the center of the dodger in the photo I attached. It's maybe 20 degrees max.

[Cheechako]

Originally Posted by Ryban

I think you're looking at the wrong bend. I'm just talking about the bend at the center of the dodger in the photo I attached. It's maybe 20 degrees max.

Yeah. I was wondering why you provided the Gemini link.
A simple conduit bender from your local rent place will do it. Or if you find the right two fence posts close enough together.... and you are technically enhanced!
I have used a conduit bender for a minor bend.

[Ryban]

Well, I tried to find a muffler shop to bend these tubes, but came up empty handed. It doesn't really help that I usually don't have time during the week, when more of them are open, to get out to these shops.

In any case, I decided to bend them myself using a small jig with the two bronze line rollers shown above.

The first tube I filled with sand, but that didn't really seem to help any, so I didn't fill the second one and it turned out the same. Both have a slight dent at the point of the bend, but given the role these will be playing, and the fact they won't be visible, I really don't mind at all.

[pcmm]

Originally Posted by Ryban

Well, I tried to find a muffler shop to bend these tubes, but came up empty handed. It doesn't really help that I usually don't have time during the week, when more of them are open, to get out to these shops.

In any case, I decided to bend them myself using a small jig with the two bronze line rollers shown above.

The first tube I filled with sand, but that didn't really seem to help any, so I didn't fill the second one and it turned out the same. Both have a slight dent at the point of the bend, but given the role these will be playing, and the fact they won't be visible, I really don't mind at all.

Did you roll the tubing over those rollers or just try to use the roller as a bending point? for the amount of bend you were trying to acheive this was simple to do with just rolling it back and forth over that roller with some pressure applied . It shouldn't have kinked like that.