Flattening Sheet metal

[chuckG]

I have designed an alluminum boat in solidworks and need to see if it is possible to make for 1, and then flatten it out so I can cut it out. I have used MultiSurf/aerohydro before but they are expensive and customer support seems to be non-existant. Suggestions? Help? THANKS!

[Guest625101138]

A hammer works well but it causes dents!

You want a "developable" shape. Unless you have a very large press or explosive pressure in a mould it is very hard to make an aluminium hull that is formed from non-developable shape. This means you must limit the curvature to a single dimension for each piece of the hull. You can torture a compound curve into a piece if it is well constrained and ductile material.

You can get Freeship on the net and it is well supported on this site. It will allow you to see if the shape can be developed. If you already have a 3D file of the hull then send me an igs of dxf version from solidworks and I can check if it is developable.


Rick W.

ah now I found ricks weakness)
what he is trying to say is you need little or no compound, compound is shape both along the boat and up the boat
Compound is easy IF you have stretching and forming machines and there is NO reverse shape as in flare bows, in short boats, you can shape flare into longer hulls

Explosives Rick, do you really believe that silly theory?
your programmes will tell your if shape is developable, but maxsurf will flatten compound shapes as will autoship,
maxsuf workshop will even tell you whrere to stretch the plates
but simpler stick to no compound

[Guest625101138]

Stu
I had some friends who experimented with explosive forming in the 80s. They were trying to produce a small dinghy for mass production. They tore up quite a lot of aluminium. One of them ended up with an Oscar as their main business was movie special effects.

Anyhow explosive forming is still in use but not doing things like boats:
http://www.exploform.com/index.php
I did see reference to forming a 35ft hull but did not find the result

I have seen skilled panel beaters do wonders with metal forming on motor car panels but it is not for the average boater. I worked with a fellow many years ago who was well known for his ability to spin aluminium for replica model 'T' parts.

I can recall photos (I think you supplied) of some large boats that have some nice compound curves in plate. So I know it is possible but it is certainly not something I have had success with in light gage metal.

I am not a boat builder I just do it for a hobby. I get professionals like you to do it if I want a good job.

Rick W

[dd24skater]

We flatten sheetmetal in Solidworks every day send me the file

dd24skater@sbcglobal.net

[alidesigner]

You can flatten with solid works in sheet metal mode but be carefull. If your shape is close to developable it might flatten on the computer but in real life it might need some slight stretch, which may be out of your tolerances.

This is where Workshop is excellent. It graphically shows you the amount of stretch in needed in the plate so you can easily tell if your plates will flatten properly. I use it for my hull shapes but do the simpler panels in SW.

Have a close look at the attached file. Even thought the girth differences are only 1 & 2mm, you can see that the strain in the middle of the plate is terrible and would make it very difficult to pull this plate into shape. I usually target strain % of 0.06 so 0.25 is way too high.

[chuckG]

Originally Posted by alidesigner

You can flatten with solid works in sheet metal mode but be carefull. If your shape is close to developable it might flatten on the computer but in real life it might need some slight stretch, which may be out of your tolerances.

This is where Workshop is excellent. It graphically shows you the amount of stretch in needed in the plate so you can easily tell if your plates will flatten properly. I use it for my hull shapes but do the simpler panels in SW.

Have a close look at the attached file. Even thought the girth differences are only 1 & 2mm, you can see that the strain in the middle of the plate is terrible and would make it very difficult to pull this plate into shape. I usually target strain % of 0.06 so 0.25 is way too high.

What version of Solidworks Workshop are you using? Do you have any addons?

[alidesigner]

I am using SW 2008, Maxsurf/T (3 surface version), and Workshop/S (plate development only version), both by Formsys.

If you want I can check your file in workshop, just email an iges or SW part file to cncmarine@yahoo.com.au If you want to protect your design confidentiality just send the surface to be checked on its own.

Originally Posted by Rick Willoughby

Stu
I had some friends who experimented with explosive forming in the 80s. They were trying to produce a small dinghy for mass production. They tore up quite a lot of aluminium. One of them ended up with an Oscar as their main business was movie special effects.

Anyhow explosive forming is still in use but not doing things like boats:
http://www.exploform.com/index.php
I did see reference to forming a 35ft hull but did not find the result

I have seen skilled panel beaters do wonders with metal forming on motor car panels but it is not for the average boater. I worked with a fellow many years ago who was well known for his ability to spin aluminium for replica model 'T' parts.

I can recall photos (I think you supplied) of some large boats that have some nice compound curves in plate. So I know it is possible but it is certainly not something I have had success with in light gage metal.

I am not a boat builder I just do it for a hobby. I get professionals like you to do it if I want a good job.

Rick W

my dear chap, I would swap my skills for yours anyday,
I did read about that exp stuff, but , well there are no short cuts in yachtbuilding

[Fanie]

Touchcad can do it

[dd24skater]

Originally Posted by alidesigner

You can flatten with solid works in sheet metal mode but be carefull. If your shape is close to developable it might flatten on the computer but in real life it might need some slight stretch, which may be out of your tolerances.

This is where Workshop is excellent. It graphically shows you the amount of stretch in needed in the plate so you can easily tell if your plates will flatten properly. I use it for my hull shapes but do the simpler panels in SW.

Have a close look at the attached file. Even thought the girth differences are only 1 & 2mm, you can see that the strain in the middle of the plate is terrible and would make it very difficult to pull this plate into shape. I usually target strain % of 0.06 so 0.25 is way too high.

Adjust your K factor!

Dd

[alidesigner]

My hull shapes have compound curvature so SW wont convert them to sheet metal unless I do a new loft between the edges but then I lose the fairing inbetween the edges.

SW is great for unfolding but that's a lot different to plate development. Sure SW will give you a flat part for any lofted sheet metal part but I havent found a way to get it to tell you how much strain is in the plate so you have no way of knowing when it comes to building it if the frames will fit.

(If anyone knows how to get a strain plot from SW please let me know)

Considering the cost of plate, cutting a plate that's not truley developable can be an expensive mistake.

Originally Posted by alidesigner

My hull shapes have compound curvature so SW wont convert them to sheet metal unless I do a new loft between the edges but then I lose the fairing inbetween the edges.

SW is great for unfolding but that's a lot different to plate development. Sure SW will give you a flat part for any lofted sheet metal part but I havent found a way to get it to tell you how much strain is in the plate so you have no way of knowing when it comes to building it if the frames will fit.

(If anyone knows how to get a strain plot from SW please let me know)

Considering the cost of plate, cutting a plate that's not truley developable can be an expensive mistake.

maxsurf seems to be tried and tested, we noticed no difference in the (flattened ) plates from rhino and maxsurf
my friends in NZ have done some very very complex shapes in maxsurf 12 with great results
http://www.bosandcarrboatbuilding.co.nz/
for some reason it would not handle the nose on the mussel harvester, which has flare

[alidesigner]

Yes Rhino will also develop plates. I'm not sure if it gives strain plots or not. If not the danger is that if it flattens a plate that is not truley developable then the flattened plate will not take the correct shape when pulled up. Nothing worse than trying to fill a 10mm gap. Thats why I like workshop because you can see how well your plate has developed and if not, the plot shows you where to re-fair it.

I have found that Maxsurf handles flare without any problems, you just need to place the plate boundaries in Workshop in a logical position to be able to develop it.

[Ed Glowacki]

Originally Posted by chuckG

I have designed an alluminum boat in solidworks and need to see if it is possible to make for 1, and then flatten it out so I can cut it out. I have used MultiSurf/aerohydro before but they are expensive and customer support seems to be non-existant. Suggestions? Help? THANKS!

I have been a MultiSurf user from its beginning and have always found their phone support to be competent, fast and professional. Call them yourself at 207-244-4100.

Regarding expense, that is subjective. MultiSurf is nowhere nearly as expensive as SolidWorks.