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juice
02-11-2008, 03:13 AM
Hi all.

Im looking at going for my trade certificate and there a a few things in the self assesment form which I am not certain on, and was after a bit of help.

I need to be competent in marking out ( on thin sheet) square to round and applying it in therory and practical.

Is there a formula for this or a specific way of going about it?

Thanx.

hotrodder
02-11-2008, 07:40 PM
just 'square to rounds' or pattern development in general?

this should get you started... http://search.sheetmetalworld.com/news/articles/197.cfm

several books on the subject can be found in this thread... http://www.weldingweb.com/showthread.php?t=17308

Sledneck
02-14-2008, 12:52 AM
Like this one? It's a double offset transition out of 1/8" plate.

It can be done both mathematically and via pattern development. Using the math is easy and only requires you to know the height, base dimensions and the diameter of the round. To layout using pattern development you have to draw a full scale elevation view of one, two or all four quadrants depending on how many ways the transition is offset. Using that view and a diagram to help you find true lenghts of the bend and center lines you can begin to lay out the pattern. I'll see if i have time to draw up some things in CAD to more easily explain the process if you like.

juice
02-14-2008, 01:41 AM
Thanx guys!
Thats great work sledneck!!!! This is just one area that I am not competent, but it seems I need to know. If you have time I would really appreciate you drawing something up, it may just explain the whole proccess a little more.

Thanx for the help hotrodder. I am going to try amazon books to see if I can get a copy of "the geometry of sheet metal work" I tried the link you gave me and had a go on some paper, but Im still a bit confused.

Thanx heaps. Cheers.

Tinbasher
02-14-2008, 01:51 AM
Same principles of pattern development apply, regardless of the scale.
16723

16724

Involves triangulation.

juice
02-14-2008, 01:57 AM
Exellent!!!

What is that for tinbasher? Some kind of exhaust stack or something?

Great stuff though. I noticed the turnbuckle. Arent they just a great thing to have in ya toolbox!! I use them all the time

Tinbasher
02-14-2008, 01:59 AM
Process piping for a mine...gotta have a turnbuckle and a good set of starters...spring steel

juice
02-14-2008, 02:11 AM
starters?? what ya mean by that ?

Tinbasher
02-14-2008, 02:28 AM
These are what we refer to as starters. Here are a smaller set used up to maybe 3/16", the ends are ground quite fine. They are used to manipulate the joint when fitting. They can be hammered up and down the joint once inserted. They are a must. Also good for making lapped connections when installing pipe.

We make them from leaf springs.Also shown is my 1-1/2 lb crosspein and a small dolly for opposing the hammer1672516726

WolfmanJack13
02-14-2008, 01:35 PM
Hey Juice , check out this link to some tutorials. I used it when i had to make up some transitions. Should help you out. Good luck.:waving:

http://search.sheetmetalworld.com/tutorials.cfm

sc6chuck9
02-14-2008, 03:19 PM
WOW,,,,, After reading all this along with viewing the sites offered I realize what I thought was a pretty streight forward simple industry isn't, it looks like a bear to me in the math anyway. I don't really think I have ever been more wrong about what I thought an industry was. My hats off to all you sheet metal men now for sure.

William McCormick Jr
02-14-2008, 11:10 PM
It is not really that hard, nothing is that hard. Nothing.

But you do have to learn one field really well, become a master in it. And after that one field you can go on to any other. I recommend an apprenticeship in some field that actually produces something.

This is my favorite method, links below. Although I can just cheat and use rough measurements, this is an exact way to do it. You almost always when doing sheet metal have to leave a small bit of metal at the top of your square to round to act as an area to bond to the sleeve that you are going to fasten to it.

This is of course going to have to be smaller then the collar or it would not fit inside the collar. So it is customary to make the inner piece smaller then the collar. Usually the square to round is a reducer so the flow is from the square to round. There could be exceptions to this but it would be rare.
This normally requires you to make a slightly longer and slightly smaller diameter round, to fit the collar. Today most collars are spot welded on or welded on, but some shops Taloc them or rivet them. You also have to deduct the collar height from your finished piece or someone will return it with an angry look on their face. Often this is a hard piece to remanufacture in the field. Ha-ha. But some guys can and you would never know.

http://www.Rockwelder.com/SheetMetal/sqtr1.jpg
http://www.Rockwelder.com/SheetMetal/sqtr2.jpg

http://www.Rockwelder.com/Welding/StackAndVents/PICT0007.JPG

Sincerely,

William McCormick

Me!
02-14-2008, 11:23 PM
How do you make the last few bends?

William McCormick Jr
02-15-2008, 10:52 PM
How do you make the last few bends?

If you are doing a lot of thin material. All of the same pieces. You can set the roto-die or you can set the hand break, or the finger break to bend more on one side then the other. You start at one end with all the material in the break, and with each bend pull more and more out of the break, until you get to the last bend.

With the roto-die you just limit how much one side of the knife comes down into the "v" channel, more then the other.

With either hand break, you can set the hold down to sit way back on one side. Basically simulating a thick piece of metal will be bent there. This makes it bend less on the set back side.

You can also decrease pressure on one side of the hold down as well. That side will bend less. But the part can slip doing it that way. Unless you also lock the bending arm in a slightly angled position and just keep bringing the hold down up and down on it. This is probably the fastest. It simulates a "V" break/brake.

On a thin one piece Square to round, in a roto-die or "V" break, I tend to bend both ends first, and then do one of the middle bends last. Always starting each bend at the outside edge and moving towards the center. It has a bit more spring, and you can position the piece more easily in the bender.

For heavy gauge stuff, I tend to do it in pieces. Either two "U" shaped halves, or four sides. If you do the "U" shaped piece you have to finish towards the middle of the piece on the last bend, using a roto-die or "V" break. In other words you start on the outside, the end, and finish in the center of the "U". This way neither side hits the knife or the carriage that holds the knife, in the "V" break or roto-die.

Sincerely,

William McCormick

Tinbasher
02-15-2008, 11:47 PM
Here is a layout for a very simple square to round, on center both ways...you need only develop a quarter pattern because of the symmetry

1679416795

this is a layout for a much more complex square to round
1679616797

oxygen454
05-11-2008, 04:17 PM
Hey Sledneck, are you from BC Canada? That looks exactally like the same design we made at BCIT? lol

I have a program that takes your start and finish points and tells you all you need to know lol. Got it from a friend way back.

William McCormick Jr
05-16-2008, 09:07 PM
I wanted to add that when I do thin small square to rounds. I actually use the cross break setting on the roto die. Hydrolic press.

This way the bottom 90 degree bend, gets hit many times and turns into a ninety. While the round top part, only gets hit once for each bend you decide to put.

Usually the 90 degree bend, is over done. By this method. But the metal is thin and it does not matter.

I was talking about my specific thickness metal, and the specific machines I use in that earlier post. Some of the heavy metal we bend requires strange procedures, or special setting of the break or roto die.

You really should make a scrap piece with the number of bends you plan to put into the square to round.

Especially on heavy stuff.

Sincerely,

William McCormick

Tinbasher
05-18-2008, 09:20 PM
We got cam-duct software at work last week...it' s pretty cool...it will layout nearly anything

19819

19820

19821

comp
05-31-2008, 01:39 PM
site is interesting

Sheetmetal guy
08-11-2008, 01:05 PM
Tinbasher,
Funny you post that this is what i do for a living...
I do cad design with the same exact program.
Makes laying out Sq2Rd's alot easier :)

Tom Kroscavage
02-08-2009, 07:40 PM
Hi all.

Im looking at going for my trade certificate and there a a few things in the self assesment form which I am not certain on, and was after a bit of help.

I need to be competent in marking out ( on thin sheet) square to round and applying it in therory and practical.

Is there a formula for this or a specific way of going about it?

Thanx.

There are three types of lay-out parallel, true length, and radial line development. You can lay-out anything with true length line development. Master this and your boss will need you more then you need him.