Official Luthiers Forum!
http://luthiersforum.com/forum/

Autocad
http://luthiersforum.com/forum/viewtopic.php?f=10101&t=37052		 Page 1 of 1
Author:  Joe Sallis [ Mon Jul 09, 2012 7:03 am ]
Post subject:  Autocad
anybody know how to put body shape templates into a programe like autocad?
Author:  letseatpaste [ Mon Jul 09, 2012 8:17 am ]
Post subject:  Re: Autocad
Do you mean taking a physical tracing and making it into an Autocad drawing, or just starting from scratch making a new design?
Author:  Dave Stewart [ Mon Jul 09, 2012 8:24 am ]
Post subject:  Re: Autocad
I expect you can take a "square on" 'photo of it, crop it exactly & paste it into Autocad. Draw a rectangle to scale (ie lower bout by body length) & fit the image exactly into it. Now you can do a line drawing tracing in a new layer or whatever, all to scale. (I do this with Turbocad, so it should work the same)
Author:  Joe Sallis [ Mon Jul 09, 2012 8:32 am ]
Post subject:  Re: Autocad
thanks for replies.
I wondered if there were already some files out there I could import?
Author:  Stuart Gort [ Mon Jul 09, 2012 10:41 am ]
Post subject:  Re: Autocad
http://www.cadguitarplans.com/blueprints/

This stuff looks pretty comprehensive and will go into AutoCad via the .dwg or .dxf format. You gotta pay though....but I haven't seen anything that comes close to the amount of detail these files present.

I'm certain there are sites where you can download free stuff. Look for file extensions; .dxf, .dwg, .iges. .stp, .x_t. and .stl. All of those should import into AutoCad. Some are surface files...some are 2D flat files.....but they all should import.
Author:  letseatpaste [ Mon Jul 09, 2012 11:28 am ]
Post subject:  Re: Autocad
You can take a photo or scan and insert it and then trace it inside Autocad. The trick is using Autocad to get the photo/scan scaled exactly right, and oriented perfectly vertically or horizontally. Then you can trace over the photo/scan in Autocad. You can even piece together multiple scans if your scanner's not big enough, you just have to make reference lines to piece them together in Autocad. It's not that complicated if you're already familiar with Autocad, it's mainly just a matter of knowing your different options with the SCALE and ROTATE commands (specifically the "Reference" options inside of each command).

Once everything is scaled and rotated into the correct position, it's easy to trace half of the body profile using the SPLINE command, then mirror it to the other side. Get to know the options of the SPLINE command, specifically how to adjust the tangent points of the first and last point of the spline. Then when you mirror half the profile, you don't end up with points at the neck or heel.

Hope that's not too vague, I use Autocad nearly full time so all this stuff is second nature to me and I might not be explaining it well.
Author:  David Malicky [ Mon Jul 09, 2012 1:16 pm ]
Post subject:  Re: Autocad
Good advice above. After squaring/scaling, it's helpful to right click on the picture and uncheck "Selectable" -- that way the pic doesn't shift accidentally during tracing. Also check "Send to back".
Author:  Freeman [ Mon Jul 09, 2012 1:37 pm ]
Post subject:  Re: Autocad
Letseatpaste nailed it - import a bit map, scale it, then trace around either using bits of straight lines, curves and arcs or a poly line. I would make some key construction lines - centerline, scale length, bridge location, widths at critical points - lock the layers with the bit map and contruction lines and connect point on them. Anyone who works with Autocad very much will know how. I use it all the time to make templates for routing, neck profiles, headstock drilling - all kinds of little things. I'll do the drawing, scale it, make a dfx file and send it to a cnc laser which cuts out my nice template - all ready for the router.

Big problem with autocad is that it is basically 2D which works fine for templates, but not for 3D solids (like a mandolin or a carved top guitar) - a true modeling program like Solidworks would be killer for that.
Author:  Joe Sallis [ Mon Jul 09, 2012 2:16 pm ]
Post subject:  Re: Autocad
good replies, thanks. I've seen that site before, Zlurgh, but at $94 a bit expensive for what i want from them.
I'm going to try the tracing method.
Still hoping someone will reply- go to www.... they have all the profiles for free download.
I'm new to autocad. I've been using it in conjunction with a laser cutter at work. I found some quality 6mm acrylic sheets. I've been making router templates too. Been trying to make a finger board template with dot positions cut out but finding can't get the holes mm perfect. A bit frustrating but it's got great protential.
Author:  Freeman [ Mon Jul 09, 2012 4:53 pm ]
Post subject:  Re: Autocad
I assume that since this is the acoustic section you are talking about laying out acoustic guitar bodies. In the past couple of years American Lutherie has had several articles about designing guitars based on chords of different circles. That would be a very good way to do it - you won't be reproducing an established design but rather coming up with your own pleasing shapes - and would fit Autocad perfectly. The other method is to establish as many points and possible and simply draw a poly line and fit the curve. The nice thing about that method is that I would think that would be a natural curve that the wood would want to follow when bending.

btw - I have an Autocad drawing of a National style tricone which is basically a 12 fret triple ought - that would be a starting point for that size guitar. That plan is in the public domain - I could send you a copy.
Author:  Andy Birko [ Mon Jul 09, 2012 6:52 pm ]
Post subject:  Re: Autocad
Freeman wrote:
The other method is to establish as many points and possible and simply draw a poly line and fit the curve.


Usually when splining, you want as few points as possible for the smoothest curve. It's often better to move a point and adjust the handles than it is to add another - at least if you want smooth and flowing geometries.

When I'm tracing a picture, it will often take a few tries to figure out the best locations for spline points. There's a really good tutorial for SolidWorks on tracing a guitar body....but unfortunately, I can't find it! I'll look around some more.
Author:  Ken Jones [ Mon Jul 09, 2012 10:45 pm ]
Post subject:  Re: Autocad
Andy Birko wrote:
Freeman wrote:
The other method is to establish as many points and possible and simply draw a poly line and fit the curve.


Usually when splining, you want as few points as possible for the smoothest curve. It's often better to move a point and adjust the handles than it is to add another - at least if you want smooth and flowing geometries.

When I'm tracing a picture, it will often take a few tries to figure out the best locations for spline points. There's a really good tutorial for SolidWorks on tracing a guitar body....but unfortunately, I can't find it! I'll look around some more.


That's been my experience working with Rhino, my 3-D design program of choice -- I start with fewer control points, then I add only as many as I absolutely need.
Author:  Bob Garrish [ Tue Jul 10, 2012 11:21 am ]
Post subject:  Re: Autocad
Rhino has a nice command called rebuild which lets you reduce the number of control points while attempting to stay as close to the existing curve as possible. I tend to trace quickly with a bunch of points, rebuild to get down to a minimum nmber, and the fine tune the placement. interpcrv is another good command that fits a curve through the points you click rather than making you drag around control points. That's how I draw the initial curve which is later simplified.

Solidworks doesn't have the same level of drawing facilities as Rhino, but the way you edit splines with the on screen handles is really nice. Being able to use tangency constraints on successive splines makes it pretty fast to get what you're after, and construction geometry can be a huge help.

Autocad brings up in me a deep and profound sadness for those who are forced by their work to use it. I can, but I find it quite painful. Draftsight is a nice free alternative, but I was disappointed to find that they'd made an Autocad clone rather than putting the Solidworks sketch tools into the software. A 2D version of the SW sketch tools, affordably priced, would be killer.
Author:  Ken Jones [ Tue Jul 10, 2012 1:55 pm ]
Post subject:  Autocad
Great Rhino suggestions, Bob, thanks. I'm looking forward to trying those commands.
Author:  Rodger Knox [ Tue Jul 10, 2012 4:47 pm ]
Post subject:  Re: Autocad
Starting with as little distortion as possible in the image being traced is important. The longest focal length you can use will give the best results. (opposite effect of "fisheye lens" which is short focal length)
In non-photographic lingo, back up and zoom in [:Y:]
Author:  muskr@ [ Tue Jul 10, 2012 6:15 pm ]
Post subject:  Re: Autocad
I find this program helpful as a starting point:
http://liutaiomottola.com/formulae/gthang.htm

It took me a while to find numbers that actually draw something, here here's something to work with:
body length: 19"
lower bout width: 15"
upper bout width: 11"
primary arc radius: 2.75"
offset from neck end: 0.45"
waist width: 8.5"
waist arc radius: 1.5"
offset from tail end: 12.4"
primary arc radius: 5"
offset from tail end: 0.75"
secondary arc radius inc: 1
Author:  Andy Birko [ Wed Jul 11, 2012 8:09 am ]
Post subject:  Re: Autocad
Bob Garrish wrote:
Being able to use tangency constraints on successive splines makes it pretty fast to get what you're after, and construction geometry can be a huge help.


Indeed. Maybe not so useful in this case but I recently re-discovered a command called "fit spline" in SW which takes and combination of edges, lines arcs whatever and simplifies it to a single spline.
Page 1 of 1 All times are UTC - 5 hours
Powered by phpBB® Forum Software © phpBB Group
http://www.phpbb.com/