# I need some confirmation



## Suzuki4evr (Jun 25, 2021)

Do I have it correct that if I wanted to make the bends on a S/Steel strip like in the pic and I am using 0.9mm sheet, that the strip should be 150mm long,149.8mm to be exact?
	

		
			
		

		
	




Michael


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## Suzuki4evr (Jun 25, 2021)

I must make 2 000 of them. Don't have a bending brake so any suggestions on a idea for a homemade one, is also welcome. I am also thinking of making a die that I use on my press to bend them. I would like to bend more tgan one at a time.


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## Liljoebrshooter (Jun 25, 2021)

It will depend on the radius of the dies.   A larger radius will make the stock grow more. 
Joe


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## Suzuki4evr (Jun 25, 2021)

It will be a very sharp bend/radius,but what that is, is hard to say.


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## Bi11Hudson (Jun 25, 2021)

Not to peddle another machine, but. . . For that many duplicate parts, I would want some "automation". Below is a link for a model builder's supplier. Horrible Fright has a similar brake at a much better price but rougher finish. I have one, having given up on the 30" brake that was much too big.





__





						Mini Metal Shear / Brake
					

Mini Metal Shear / Brake.This double-featured miniature machine will save you hours of tedious sheet metal fabrication and finishing. 371010.




					www.micromark.com
				




Edit: The described metal is "about" 0.035 inch, a size I work regularly in brass. Stainless would be "tougher", but for the 3/4 inch width, well within the capabilities of such a small brake. The shear portion might be a problem. . . My work involves cutting complex shapes by hand and then folding on the brake.

.


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## RJSakowski (Jun 25, 2021)

There are a number of factors that influence the final dimensions, thickness of the material and the radius of the bend to name two.  As a rough guestimate, the material will bend around a point approximately midway between the inner and outer surface.  You can calculate the actual dimensions of the flat sheet, given the final dimensions and bending parameters.  SolidWorks has a sheet metal function where the finished part is drawn and the sheet then flattened.  The dimensioned 2D drawing of the sheet will give the necessary information.

To determine proper dimensioning, I will lay out a part in the flat and make careful measurements from the bend line to the ends of the piece.  Then I will bend and measure the actual distances, the difference giving me the corrections required.  

Considering you want to make 2,000 parts, I would make a custom bending jig. It will help to ensure uniformity of parts I have made jigs for similar,albeit smaller parts.


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## Winegrower (Jun 25, 2021)

Per RJ.  You better make one first and check it.


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## Liljoebrshooter (Jun 25, 2021)

I would cut a piece exactly 40mm long and put a bend in the center and measure each side to determine what is changing.  At work we use a top die with a 094" radius.   This will generally add one material thickness to each side of the corner.   
Joe


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## brino (Jun 25, 2021)

Suzuki4evr said:


> Don't have a bending brake so any suggestions on a idea for a homemade one, is also welcome.



We need a bit more info to make any recommendations.

two more dimensions: sheet thickness, and length of bend.
material type will affect the strength of machine required

-brino


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## Lo-Fi (Jun 25, 2021)

Draw it up in OnShape using the sheet metal feature, it'll tell you exactly where you need to be heading given your desired bend radius and K factor for the material. Achieving a bend radius below the thickness of the material is not usually wise or achievable, for what it's worth. 

I made a die for a similar job:


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## Suzuki4evr (Jun 25, 2021)

I am not sure yet how I am going to bill this apart from material price,so I am not sure if the profit will be enough so that buying a bender will be justified.


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## Janderso (Jun 25, 2021)

Great thread Suzuki, good information gathered.


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## Suzuki4evr (Jun 25, 2021)

Liljoebrshooter said:


> I would cut a piece exactly 40mm long and put a bend in the center and measure each side to determine what is changing.  At work we use a top die with a 094" radius.   This will generally add one material thickness to each side of the corner.
> Joe


Why 40mm?


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## Suzuki4evr (Jun 25, 2021)

brino said:


> We need a bit more info to make any recommendations.
> 
> two more dimensions: sheet thickness, and length of bend.
> material type will affect the strength of machine required
> ...


Brino in my first post I think I mentioned thickness at 0.9mm stainless steel sheet and the internal length is 110mm with sides of 19mm from internal base to the top of the side.


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## Suzuki4evr (Jun 25, 2021)

brino said:


> We need a bit more info to make any recommendations.
> 
> two more dimensions: sheet thickness, and length of bend.
> material type will affect the strength of machine required
> ...


I do have a pneumatic hydraulic 10ton press.


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## Suzuki4evr (Jun 25, 2021)

Lo-Fi said:


> Draw it up in OnShape using the sheet metal feature, it'll tell you exactly where you need to be heading given your desired bend radius and K factor for the material.


Pardon me,but is this a computer program?


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## brino (Jun 25, 2021)

Suzuki4evr said:


> Brino in my first post I think I mentioned thickness at 0.9mm stainless steel sheet and the internal length is 110mm with sides of 19mm from internal base to the top of the side.



Sorry Michael it's my fault; I entirely missed the thickness and material you stated.
I need to slow down and read better.

But we're still missing the length (or is it width?) of the bend right?
(ie. do you need a 200mm brake or a 1000mm brake to do this.)

My apologies,
-brino


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## Suzuki4evr (Jun 25, 2021)

brino said:


> Sorry Michael it's my fault; I entirely missed the thickness and material you stated.
> I need to slow down and read better.
> 
> But we're still missing the length (or is it width?) of the bend right?
> ...


You are apologizing too much my friend. No worries here.

I will put it like this if I am a bit unclear. The bended side is 19mm long basically and the strip is 19mm wide and the internal length is 110mm. My client uses it as a mold of some sorts to make fire lighters from some specil cement and the end product is 110mm×19mm×19mm. Hope this helps for clarification. 

Don't worry we are still friends


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## RJSakowski (Jun 25, 2021)

As to the original question about dimensions, here is a SolidWorks drawing reflecting the final dimensions and the flat sheet dimensions.  I made some assumptions as to bend radius and width. but you get the idea.

Edit: I used .8mm instead of .9mm for the thickness on the drawing.  The second drawing reflects a .9mm thickness and I also changed the inside bend radius to .25mm.


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## Suzuki4evr (Jun 25, 2021)

RJSakowski said:


> As to the original question about dimensions, here is a SolidWorks drawing reflecting the final dimensions and the flat sheet dimensions.  I made some assumptions as to bend radius and width. but you get the idea.
> 
> Edit: I used .8mm instead of .9mm for the thickness on the drawing.  The second drawing reflects a .9mm thickness and I also changed the inside bend radius to .25mm.
> 
> ...


Thank you very nuch RJ for this, I realy appreciate it. O the width is also 19mm. Once again thank you.


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## Rex Walters (Jun 25, 2021)

Winegrower said:


> Per RJ.  You better make one first and check it.


This made me laugh! (Imagining someone making 2000 and *then* checking is like a Mitch Hedberg joke.)


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## Suzuki4evr (Jun 25, 2021)

Rex Walters said:


> This made me laugh! (Imagining someone making 2000 and *then* checking is like a Mitch Hedberg joke.)


O son of a boring bar.......that would be a  disaster


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## brino (Jun 25, 2021)

Oh someone would want those "bad" parts eventually.....the trick is living long enough and remembering where you put them! 

-brino


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## mattthemuppet2 (Jun 25, 2021)

you'd want to make a die that locates one edge of the flat stock, then does both bends at the same time. I'd make it out of alu first to work out exact dimensions, then one out of steel. Doing 2000 on a hydraulic press would get old really quickly, an arbor press would be much quicker.

I'd bill materials + 100% for the pieces, plus around 10 hours at whatever rate you think is appropriate for the die design and making. Hopefully that'll make enough profit to buy an arbor press


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## Suzuki4evr (Jun 25, 2021)

mattthemuppet2 said:


> you'd want to make a die that locates one edge of the flat stock, then does both bends at the same time. I'd make it out of alu first to work out exact dimensions, then one out of steel. Doing 2000 on a hydraulic press would get old really quickly, an arbor press would be much quicker.
> 
> I'd bill materials + 100% for the pieces, plus around 10 hours at whatever rate you think is appropriate for the die design and making. Hopefully that'll make enough profit to buy an arbor press


Sounds like a plan


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## Suzuki4evr (Jun 26, 2021)

mattthemuppet2 said:


> you'd want to make a die that locates one edge of the flat stock, then does both bends at the same time.


I am thinking of making a mold and to that can take 5 or so strips at a time. Doable?

My press has a footpedle. That helps


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## mattthemuppet2 (Jun 26, 2021)

as long as you can keep them all aligned against the work stop, no reason why not. It would certainly speed up the processing time!


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## Suzuki4evr (Jun 26, 2021)

I guess I should harden the mould and die.


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## mattthemuppet2 (Jun 26, 2021)

you're not working with thick material, so you might be able to get away with some pre hard steel. I'm far from being an expert though.

One thing I will add though is that some stainless is an absolute bear to bend without cracking. I don't know the grade, but one piece I have always cracks before 90deg. then I forget about it, put it in the pile and remember why it's in the pile next time I try and bend some. So you may need to do some experimenting with grade and corner radius.


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## Suzuki4evr (Jun 27, 2021)

Will be using 304 stainless,I think it will be ok.


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## mattthemuppet2 (Jun 27, 2021)

I dunno how good that is for bending and no idea what grade the stainless I have is that won't bend. All I know is 303, she's for me, 304, she's a .....


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## Suzuki4evr (Jun 27, 2021)

mattthemuppet2 said:


> All I know is 303, she's for me, 304, she's a .....


year older????


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