Bending Aluminum Rectangular Tubing

A 3 roll bender need not be a large outlay of money, the alternative is an undefined outlay of time and a good scrap pile. A friend and I are building one at the moment but NOT with the intention of bending aluminium RHS, we want it for steel & stainless steel pipe and flat bars.

You do need at minimum a metal lathe though.

PDW

 

PDW, good luck with your project. We have a small roller bender here, so if you need any dimensions ie distance apart of rollers etc. give me a nod and I may be of assistance.

Getting back to the original request of bending aluminium RHS, I try to keep to the topic as first posted.

The request was for bending ali RHS for a boat, I took that as one boat. It would not seem logical to me, to go to the trouble of making a roller bender for one boat, or buying a roller bender for one boat.

I have never seen a roller bender for ali RHS, but in consideration of how it react to bending, I would assume a more complex arrangement of rollers would be required than that for bending steel.

Also taking in to consideration that ali RHS is not going to be cheap, taking the risk of bending it and stuffing it up is too great. Getting it curved by a professional bending company is the best option.

Even companies making products outsource some of the manufacturing proccess.

As to using other cross sections of ali, or suggestions of welding seperate components together, does not answer the question as originally asked, and he is probably quite aware that he could fabricate curved RHS.

 

Poida-- the question was " how to bend" one method is using a bending machine another is without a bending machine by making use of cutting slots manually bending and welding.The end result will be the same. As an experienced boat builder of some 40yrs. in wood/glass and metal (alum. & steel) where ever possible i use a bender (labour cost savings) but where not i use the slot method both for alum. and steel. It's an often used and accepted practise in metal fabrication and generally involves boxed cross sectional tubing especially where specialized bending machinery is not available or as Ad Hoc pointed out the metal could suffer from stress fatigue as a result. While the slot method is not pretty and with alum. stength is lost one can use oversize or reinforcing to compensate. By the way the slot method is also used in woodworking generally on ply. to form tight curves. Very common in furniture and as a backing in curved walls and archways.

A yacht is not defined by the vessel but by the care and love of her owner--

 

Viking mate, your method of bending is correct and a standard method of bending and as you said for bending wood as well. I did not say I had an issue with such a method of bending.

However if that type of bending employed I would not recommend slotting as you would with timber but using short sections of flat RHS to form the curve.

 

30 years ago I wanted to make a rear carry rack for my ute with a profile that matched the factory bar just behind the cab. I cut out a series of small V sections until I had the curve I needed and then welded up the joints. Basically the same as Viking says. It worked quite nicely and, seeing I still have the truck, has stood the test of time. As Ad Hoc points out, you're going to lose strength welding or bending alumin so one hopes the designer has factored that into his design calcs.

I used to have a RHS bender at work and it always crushed the tube as part of the bend when doing 90 deg bends. We never used it on anything but thin wall steel.

PDW

 

One of the problems with pipe benders is, they are made for a specific OD, which is not quite correct as they are made for a specific ID with a standard wall thickness. I'm even arguing with myself now. With standard pipe they worked quite well.

Then other pipe and tube sizes came on the market and the standard pipe bender was fairly useless.

 

What size craft is this?
Bending alloy RHS is not the best approach and you have a lot of unnecessary material adding weight and expense. The framing in the fore part of the craft is under the greatest cyclic load too and bending alloy like this produces some significant slip planes that will be crack starters. And they will crack eventually. You also have a very small gap which will hold water and exclude air. Better to use channel (C section) anyway rather than RHS .

If you cut frames from sheets you will not only do a better job but you'll use less material. Usually the only bending you should be doing in frames and stringers is a bend which you can spring the material to unless it's non structural edge finishing and decoration.

 

Your are correct Mike. (I've learnt not to dissagree with you)

The RHS is not large and looks to be around 25 x 50 by visually scaling other items around and appears to merely form a splash guard.

I guess in production curving the RHS is quicker than welding seperate components. The bending of any section destroys its original integrity but as is in this application the flanges are strengthened by the attachment of the outside skin.

If you are talking channel I assume you mean installed with the open side down which does leave much of a surface to support the skin and could produce ruts in the sheeting.

However the whole exercise in construction may also be to hide the superstructure of an aluminium craft that is otherwise welded on the outside and the extra expense of construction is to appeal to a wider market.

It would be interesting to see the companies finished product.

 

Ci sono 3 metodi per curvare un profilato di alluminio.
1) fai dei tagli su 3 lati con un seghetto, lasciando intatto il lato lungo. Poi saldi a punti

2) Pieghi con una curvatrice, possibilmente CNC, che abbia le ruote adatte.

3) Usi una piegatubi da edilizia con gli stampi adattati al tuo prifilo.

Se non devi lavorare in serie, il primo sistema é perfetto. un taglio ogni 5 cm.

Ciao


There are 3 methods for bending aluminum profile
1) make the cuts on three sides with an hacksaw, leaving intact the long side. Then weld a points.

2)With a bending machine, CNC controlled. Is not sure that bending machine has wheels for your tube.
3)Use a manual bending machine, after having adapted to your tube (full of sand).
If you do not have to work in series, the first system is perfect.
Cut every 5 cm.
Hello

 

Something like this, fitted with squared rollers would work.

http://www.carellcorp.com/cphv190new.htm

 

Personally, I would take the pieces to a machine shop and have them done there.

Save $$$$$$.

 

Exactly! The xetm 60 tube bender is a CNC bender. Buy one costs at least € 5000, and even if you go to those who have one, you have built rollers to fit the profile ($ 200-400).
The only way is to cut on 3 sides and then u are able to form by hand.

Then weld just with points.
The method with sand is for manual bending; but you have to fit the shape of tube.

Regards
Gian

 

Instead of bending tubing, bend deep channel. The hull skin will form the 4th side.

 

Exactly--Milan as per my posts #2 & #18. Thought for awhile I might have to dig out my latin notes or phone my friend Sammie in Sicily for a complete translation. I could read some of it thanks to my time with my Italian friends in Toronto in the old days. (good heavy home made red wine made right from the grapes)
Actually the bow section of the craft in question could be framed in flat bar with bulkhead webbs welded longitudionally on center which in turn would form a bow section having compartments below the deck area. If you view the photos in the origional thread (not this one) one would see this is another good option especially if the deck had an access hatch. Storage of a seperated cargo would be a plus.

A yacht is not determined by the vessel but by the care and love of her owner--

 

Hoyte--On second thought ,the use and orientation of that channel is the best system to go with. It's been my experience that flat surface framing against flat surface ( skin) could result in corrosion between the two. Mostly from fine trapped materials getting in between the two thru the stitch weld voids. With the channel welded as you describe it tends to flush better---Geo