Full Version: Thanks and help request

Hello everybody!

I'm a fresh MoI user from Estonia, my background is in graphic design. Few years back I thought I'll take a look into 3D CAD world and perhaps make something real. I tried FormZ, Alibre Atom, FreeCAD and bought ViaCAD Pro 10 with PowerPack. I even took a peek at MoI back then but never downloaded trial because it seemed to have much less tools than other softwares with similar price. So years passed and I didn't do really anything in ViaCAD, even though it felt the best of the lot, it still doesn't feel like I really want to use it.

Couple of months back I thought I'll make some brackets and other items for my motorcycle and started looking around what new software is out there. I downloaded MoI and almost instantly bought a licence. Wow, I mean wow, this software is really good. It feels completely different to others: how it looks, building objects, controls, rotating, etc - everything feels natural. Now I have done some 3D printing and some metal work and all thanks to MoI.

Thank you very much Michael and others who have contributed!

With my last project (files attached) I run into some difficulties. I made a 3D bracket (5 mm aluminium sheet with some bends), exported it to STP and sent it to local manufacturer. Unfortunately the manufacturer, who uses SolidWorks, said it doesn't unfold. SolidWorks opens it fine and there are no error messages, only thing that manufacturer said is that SolidWorks makes my bracket into solid body. I have no idea why this is a bad thing. Eventually I unfolded the bracket in MoI myself and sent that to manufacturer. I don't know if I did something wrong or if the manufacturer is incompetent. I really appreciate if somebody here can help me with this issue.

Now when the excellent dimension tool is coming, I have one question for Michael: is it possible to make MoI to show the length of an arc like it does show radius of an arc?


Cheers,
Oliver

Attachments:
Oliver_5mm-al-bracket.3dm
Oliver_5mm-al-bracket.stp
Oliver_5mm-al-bracket_UNFOLD.3dm

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Hi - No problem with your file just lack of knowledge to the manufacturers your sending to. No problem with part as solid exporting as step is common practice I do it all the time. I design many parts as sheetmetal in MOI then convert in SW for output. When importing into SW need to convert the part into sheetmetal. Here are files for you to send back to your manufacturers.

Here is a project I just completed last week all sheetmetal designed in MOI then output for manufacture in SW2018.

Image Attachments:
convert sheetmetal.JPG  flattened.JPG  moi sheetmetal.JPG 

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Hi Oliver,

re:
> Now when the excellent dimension tool is coming, I have one question for Michael: is it possible to
> make MoI to show the length of an arc like it does show radius of an arc?

I had not planned on anything specific for that but could you please show me an example of what it looks like?

One thing that could make that difficult is the radial dimension entity doesn't store enough information in it to record an arc, it only has a center point and a point on the circle.

The one that does store an arc though is the angular dimension.

- Michael

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Here is a typical SW bend info PDF which is sent to manufacturer. I have noticed you have used R10 for this part size - R3 to 4 would be more appropriate for the material thickness.

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Hello Alex,

this is absolutely fantastic, great info.
Thank you very much for your quick help and attached files!

I'll do these corrections to my bracket and look for new manufacturer. It felt like current one lacked interest or expertise.


Thanks again!
Ol

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Hello Michael,

when I unfolded my bracket, my thinking was like this: I calculate the length of every bend (arc) and then I draw new plane with same length. Then rotate other surfaces to the same plane and join them all together. I thought that it would be great if MoI could show me the length of the bend (arc) so I don't have to draw help lines and do the mathematics.

I guess If others never felt the need to know the length of an arc then my workflow has to be faulty and there is probably a better way to do it. I just have to figure it out.

Possibility for quick and direct dialogue with the developer makes MoI even more unique.


Thank you!
Ol

Image Attachments:
Oliver_5mm-al-bracket_EXPLN.png 

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Hi Ol, so there is a plug-in that can help you with that, it's called UnwrapCurve and you can find it here:
http://moi3d.com/forum/index.php?webtag=MOI&msg=5136.1

It will create a line that is the length of the curve you have selected, and then if you select the line the properties panel in the upper right corner of the main window will display its length.

Or also there is a script here which you can set up on a shortcut key that will put the length of the selected curves as text in the clipboard that you can then paste in:
http://kyticka.webzdarma.cz/3d/moi/#CurveLength

- Michael

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Hello Oliver,

here is a little bit basic knowledge that may help you.

Every material and alloy has it's own minimum bending radius.
A thumb rule for soft steel and VA-stainless steel is the minimum inside radius = thickness of the sheet.

At the other side you may have aircraft grade aluminium alloy with a radius 5 times or more
of the thickness to avoid cracks on the outside of the bending line.

If you google the technical data of your material you will find two numbers named "Rm" and "Rp0,2".
The first is the absolute strength of the material in Newton or Megapascal per mm^2.
The second and smaller number is the border between elasticity und plasticity of the material.
It is clear- the load of the material shouldt stay inside the elasic range.
If the load always change from one side to the other it shouldt be not higher then 50% of Rp0,2 if you are
using black steel und not more then 30% with aluminium.

The next thumb rule say that Rp0,2 is about 80% of Rm with the most black steel alloys.
Not so with VA. Here you have not more then 20 - 25 %. That means it has a much higher range of plasticity and hold less
forces than a black steel with the same Rm-number.

What has this to do with bending of sheet metal?

Most sheet metal shops are working with laser cutter and bending press devices.
The bigger part of working is with stainless steel sheets. Typical material number 1.4301.
There are different toolsets for the press. Because time is money they dont like to change the tools to much.
Sometimes you can find an inside radius of 3 mm with a 5 mm thick sheet on a stainless steel construction.
Here it is not a big problem. Because of its plasticity you find no cracks on the outside of the bending.

The old style bending mashines, where you pull the sheet around a bar with the right radius on the edge are the only
way you can get the radius you want.

With the modern bending presses they have a script with a lot of numbers to every tool.
The radius change with every degree of the bending angle in every different toolset and material!

Other influences are: the type of material (alloy), the charge they got delivered, bending with or across the grain.

In all cases where safety of the part is importend, please ask the people of the shop first wich size of radius they can
establish with there tools, the material and the angle of your bending. If the radius is a little bit bigger than the minimum
radius you need it's ok. Then you can change your drawing radius.
If the radius is below the safety number they have to change the toolset.

As long as you do the bending works not for yourself you don't have to make the drawing for the flated part.
You are not responsable for the right length of the cutting and all the mathematics. A good shop need the drawing
of the ready construction, the minimum bending radius and the tolerance of the lengths.
Only the shop is responsable for rigth sizes of the cutting.

Good shops around my hometown and everywhere works with tolerances of +/- 0,1 mm.

In the case you have a flat sheet without any bending and with some curves on it you give this as a .dxf data
with the scale 1:1 and without any frames and script fields to the shop.
Write the thickness on it - thats all.

Hope this help you a little bit.......good luck......have fun

Hans

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Hello Michael,

those are really helpful, thank you!
Things are getting better and better.


Cheers
Ol

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Hello Hans,

thank you very much for sharing your wisdom, I really appreciate it!

I remembered that aluminum needs bigger radius, so I thought that 10 mm is that kind of number that every manufacturer can do. I guess I shouldn't have guessed.

Now I have better understanding what to ask and what to expect from the manufacturer.


Cheers,
Ol

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Hi Oliver,

please see this thread https://moi3d.com/forum/index.php?webtag=MOI&msg=7406.1

It could help you, maybe.
Ciao
Mik

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Hello Mik,

thank you for the link! That is rather interesting discussion.


Cheers,
Ol

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