How to bend a flange 180 deg

marius_baard

I can bend it 170 deg but not 180, why not

lana

Limits on flange angle are 1-179 degrees. 180 case would not fit the feature design. e.g. , length of flange is measured from the virtual intersection of external walls. That why we will be doing a separate implementation of Hem as well. 

jackson_king

I found that by increasing the flange length a lot, i.e. if you had spec'd a 1" flange, you might need to increase it to 3" or 4".  By messing with it that way, I could get 179 degrees out of it & I think that is the max value allowed by onshape.  I also had to reduce the size of the inside radius to 0.001".  I think a Hem bend of 180 degrees might create some interesting geometry issues.  I used to use solid works and it had a separate command for Hem bends.

lana

Limits on flange angle are 1-179 degrees. 180 case would not fit the feature design. e.g. , length of flange is measured from the virtual intersection of external walls. That why we will be doing a separate implementation of Hem as well. 

jackson_king

Hopefully OS will also be adding the ability to add tabs/short flanges to a sheetmetal edge.  i use a tab and corresponding slot to align parts.  I know I can finish the part and add the tabs but that is not the best workflow since I really want the tabs to be cut with the rest of the part.  I may offset the face and do an extruded cut to remove the extra material.

Research_01

As a work around could you do 2 90 degree bends close together? It is far from ideal but it would work in a pinch https://cad.onshape.com/documents/2f6376164c45f1303946c13f/w/eeac6d4587d4554434feba2c/e/0545b09f63eef2ec34e6c4f7

brucebartlett

Hi @lana,

I was going to request a Hem feature too.  I had a requirement for a safety edge and was able to achieve this by juggling the angle and bend radius and moving the flange edge but not ideal as it isn't 180deg and takes a bit of messing around. A single feature Hem would be perfect.

You can also see in this picture a requirement to align the first flanges flat around the top edge, it would be really cool if you could achieve this with a mitre on faces approaching with compound angles.

lana

@brucebartlett, Could you please share this model with Onshape support, I'd like to make sure I understand your miter alignment request correctly. 

andy_denley

I would like to add to the request for Hem fold. The lack of this feature / ability to create a 180 degree return bend is a major weakness when creating sheet metal. I have tried all methods I know and none work. 179 degrees is not good enough from software that is paid for!

bryan_lagrange

This is the closest I could get a hem profile and generate a flat pattern. The flat pattern is not accurate. You would have to do some manual calculations and adjust the flat pattern in the drawing to make it accurate for production purposes.

noa

While it is no replacement for a true hem feature, here is a workflow that I documented as a workaround. It will give you a result very similar to @bryan_lagrange's.

bård_olsen

I do not understand why they made a HEM feature where you can not select a line as starting point, but rather an edge...it is just useless, when the goal of a hem is to fold something 180 degrees starting from a certain line and in or outwards. Basically what is needed is something like MBartlett21's Fold SM, but letting you do 180 degree folds, and adjust the radius and thickness of the fold. In some metal jobs the goal is to hem as flat as possible to the other part, not 1 degree off only 179 degrees. It should be possible to specify the space between a finished fold all from 0-xxx mm so you can litterally have the two surfaces touch each other. The built in HEM feature is useless.

NeilCooke

bård_olsen said:

I do not understand why they made a HEM feature where you can not select a line as starting point, but rather an edge...it is just useless, when the goal of a hem is to fold something 180 degrees starting from a certain line and in or outwards. Basically what is needed is something like MBartlett21's Fold SM, but letting you do 180 degree folds, and adjust the radius and thickness of the fold. In some metal jobs the goal is to hem as flat as possible to the other part, not 1 degree off only 179 degrees. It should be possible to specify the space between a finished fold all from 0-xxx mm so you can litterally have the two surfaces touch each other. The built in HEM feature is useless.

Not sure what you mean by starting from a line? Surely the point of a hem is to strengthen an edge or to remove the sharp edge and therefore you would model the edge / final location of the hem? Also interested as to why you are starting from a flat sketch and then folding? Is it because you are modelling an existing manufacturing drawing of a flat pattern? 

Also, if you use a "straight" hem (which you have) then it is 180 degrees - there is an offset (for kernel tolerance reasons) of 20 microns - good luck measuring that on a real sheet metal part! Saying it is useless is not helpful - if you want to suggest improvements, please do so in the category on the right -->