Hi there,
I am sitting over a shape,
that needs to be created, /(see picture)
I started with the ground shape,
build up with 3 point arcs,

But all tools I use on the shape
create some chaos, but not the harp.

I am a beginner,
if you could guide me a little?

Thanks so much
ska234

this is the ground shape.

Hi there, that piece of harps I think it's hand crafted with a carve, so basically you would have to create the shape without carve and then make the carve with a boolean..
Second way could be making that surface separately since you don't need the continuity (as shown in the photo).
M.

Hi ska234 - it kind of looks like you're currently trying to draw an 2D outline curve that's not what is called a "plan" curve (a blue-print like view of the Top or side of a shape), but rather you're trying to sketch what is a 3D angled view of the harp.

You can't really construct a 3D shape from a 2D curve traced that was traced only from a 3D angled view, you need to construct the main curves from "Plan" blueprint views instead...

Also like Max writes above you probably will want to go through somewhat of a carving process - some areas of your model will be formed from some larger piece of stock material (formed from an extrusion for example by drawing a plan curve and using Construct > Extrude), and then some booleans will be done on that object to carve away parts of that stock material, rather than trying to draw everything directly in its final place right from the start.

Your harp is unfortunately a fairly advanced type shape to work with in a CAD program, I would encourage you to spend some time working on more simple shapes where they are more fully defined by their plan views first to gain familiarity with how MoI functions for a while before trying to tackle a more difficult project like the harp.

Try going over the introductory tutorials here first:
http://moi3d.com/3.0/docs/tutorials.htm

- Michael

Some ideas :)
take a wood cube...


You can make that for some separated parts
Then Move & Past them at the end with a Boolean Union

Hi ska234

There are some pictures of a Blue carbon fiber harp here, which show the knee.
http://www.blevinsharps.com/index.php?main_page=index&cPath=342

Consider the strings as residing in a vertical plane, at the center of the soundboard.
The strings are attached to "pins", which offsets them from the top "harmonic arm", by a fraction of an inch/cm.
The harmonic arm is (mostly) just a flat board, with various curves cut with say a bandsaw.
The harmonic arm is located on one side of the center plane, except for a part of the knee.
So to finish the knee, add on another block of wood, which begins at the base of the pins, and extends across the center plane,
over to the other side of the sound board structure. Remove parts of this block to match up with the arm, with say arcs, as per PILOU,
(Of course the harmonic arm could be carved out of one piece of wood...)

- Brian

String length, in case someone decides to build a harp :-)
http://www.harpsatsang.com/harp_design/data/stringcalculator.html

Also, a free music Notepad program can be downloaded.

- Brian

Hello, and thanks for the answers and ideas,
I started with the cube,
and when I try to draw curves through the cube,
it cuts either nothing, or strange results.
(I went through the tutorials and can make crowns :-)








maybe it´s just a lack of imagination what exactly needs to be done?

by the way:
the picture from the harp is carved by hand, band-saw etc.
My skills are there - still It would be so handy to have this drawn.

best regards, ska234

Hi ska234,

re:
> and when I try to draw curves through the cube,
> it cuts either nothing, or strange results.

Could you please post an attachment of the 3DM files with the cube and curves you've drawn so I can take a look at your geometry?

That will help a lot to better diagnose what's going wrong with those cases, it's a lot easier to tell what's going on when I'm able to examine your objects, repeat the boolean steps, look at things from different angles, zoom in, etc...

- Michael

sure!

Hi ska234 - thanks for posting the file!

So I think what you're running into is trying to use 2 cutting curves that happen to touch each other at a shared endpoint. The booleans will try to automatically join together curves as a part of the boolean process and in your case here for example:



if those 2 cutting curves get joined together since they're on different planes the resulting joined curve is not on a single plane anymore and so does not know which direction it should be extruded in to form the cutting surfaces.

In case like that with 2 curves in different planes coming to a shared endpoint you will need to do the boolean in 2 passes, one for each individual curve rather than using both curves in the same single boolean operation.

Is that one of the things you're running into?

If it's not that and you're having a problem with one of the other curves maybe you can post a file with just the one solid and one curve in it so I can know for sure which particular one is giving you the trouble.

- Michael

Hi again,

I am one step ahead,
but the upper shape is tricky...

I tried Boolean, or projekt,
the results are inpredictable...

Any ideas?

Best wishes! ska234

Your picture looks similar to "gwen".
http://artefakt-musik.de/gwen.htm

Most of the harp pictures are at an angle.

The top of the korpus (Sounding Board) is (CORRECTION) 8 sided.

- Brian

http://www.magus-harps.de/HarfenIrisch2.html


- Brian

I think it's actually Bluebell, because..

Hi ska234,

> I tried Boolean, or projekt,
> the results are inpredictable...

Is it with this curve here? :



It looks like the problem is that curve is not planar, it swoops around in 3D space a bit, I think because this particular control point is just slightly not in the same plane as the others:


I drew in a plane using Draw solid > Plane > 3pt, then enlarged it slightly using the edit frame in the corner, then I projected the curve onto that plane:



The result is in the attached 3DM file, it should now do a boolean with it - the booleans won't work with non-planar 3D bending curves because they don't know which direction they should be extruded out into with the automatic extrusion processing.

You may need to use View > CPlane to set your drawing plane, or put in a plane like I've done above and draw on that to make sure the points you are placing are all on one plane. Hope this helps!

- Michael

Hmm, Bluebell looks different. Gwen has a different top. Must be a hybrid.

This picture looks close. I think there are 31 strings.



- Brian

Lots of harp information here:

http://harpomania.blogspot.se/

Includes fairly good translations from French.

- Brian

I might try making a harp this winter, but will probably loose interest first.

Hi ska234:

As Max correctly says,harp is made by different pieces joined together as picture shows,so you can model pieces separately




To achieve the shoulder you need to consider the whole pieces of the harp to get correct shapes.I attached the file of my test
take a look at the layers so you can understand how i did the pieces
Use it and if you like,do the rest :)

M

thanks to you all so far !
I managed to draw it myself now.