computer lofting software

[hank woll]

hello-has anyone got the skinny on software for lofting?-i know it is available but where?-hank

[hank woll]

hello-has anyone got the skinny on software for lofting?-i know it is available but where?-hank

[hank woll]

hello-has anyone got the skinny on software for lofting?-i know it is available but where?-hank

[gert]

I just used ACAD

[gert]

I just used ACAD

[gert]

I just used ACAD

[Bruce Hooke]

I've used AutoCAD but I can't imagine how you could effectively use it to fair the lines, which should be part of the lofting process...

[Bruce Hooke]

I've used AutoCAD but I can't imagine how you could effectively use it to fair the lines, which should be part of the lofting process...

[Bruce Hooke]

I've used AutoCAD but I can't imagine how you could effectively use it to fair the lines, which should be part of the lofting process...

[Ken Hutchins]

Bruce, to fair a line zoom in on a suspect area, edit the spline, delete a point at the suspect area. If the spline moves it is not fair. create a new point on the new spline. A bad point on a spline will show a pronounced wave in the spline. after recreating the spline check it in 3 views. This process will work in most CAD systems so long as you are working in 3D, if you are working in 2D it can be done but you have to duplicate the effort for the other directions.

[Ken Hutchins]

Bruce, to fair a line zoom in on a suspect area, edit the spline, delete a point at the suspect area. If the spline moves it is not fair. create a new point on the new spline. A bad point on a spline will show a pronounced wave in the spline. after recreating the spline check it in 3 views. This process will work in most CAD systems so long as you are working in 3D, if you are working in 2D it can be done but you have to duplicate the effort for the other directions.

[Ken Hutchins]

Bruce, to fair a line zoom in on a suspect area, edit the spline, delete a point at the suspect area. If the spline moves it is not fair. create a new point on the new spline. A bad point on a spline will show a pronounced wave in the spline. after recreating the spline check it in 3 views. This process will work in most CAD systems so long as you are working in 3D, if you are working in 2D it can be done but you have to duplicate the effort for the other directions.

[AHall]

Ken: I am very interested in any information you can share regarding lofting with Autocad. I am a Autocad user, but all my work is done in 2d (utility work mostly)

What I would love to be able to do is take a plan that I have and calculate the hull volume below the waterline. If all goes according to plan, I will use this displacement for my engine/prop sizing.

If it matters, The boat is an Arno Day 28'x10'cedar on oak lobsterboat.

any suggestions would be great.

Thanks,
Andy Hall
Lynn,MA

[AHall]

Ken: I am very interested in any information you can share regarding lofting with Autocad. I am a Autocad user, but all my work is done in 2d (utility work mostly)

What I would love to be able to do is take a plan that I have and calculate the hull volume below the waterline. If all goes according to plan, I will use this displacement for my engine/prop sizing.

If it matters, The boat is an Arno Day 28'x10'cedar on oak lobsterboat.

any suggestions would be great.

Thanks,
Andy Hall
Lynn,MA

[AHall]

Ken: I am very interested in any information you can share regarding lofting with Autocad. I am a Autocad user, but all my work is done in 2d (utility work mostly)

What I would love to be able to do is take a plan that I have and calculate the hull volume below the waterline. If all goes according to plan, I will use this displacement for my engine/prop sizing.

If it matters, The boat is an Arno Day 28'x10'cedar on oak lobsterboat.

any suggestions would be great.

Thanks,
Andy Hall
Lynn,MA

[Ken Hutchins]

Andy, what you need to do is find the area of each section, this can be done with TOOLS INQUIRY AREA then pic points around the area (hull shape). All points must be in sequence and the start point and the end point must be connected CR and the resulting area will be displayed. Do this for each section. The volume between 2 adjacent sections will be the average of the 2 values times the spacing. Now this might produce a slight error depending on the total hull shape but for all practical purposes the results will be just fine for what you want. If you have 3D available you can create a poly line of the hull shape, extrude the poly line to the section spacing and get the volume of the resulting soild with TOOLS INQUIRY MASS PROPERTIES, do that to 2 adjacent sections and then average the result.
Basically what you would be doing with CAD is what would be done with a planimeter in the days of old.

[Ken Hutchins]

Andy, what you need to do is find the area of each section, this can be done with TOOLS INQUIRY AREA then pic points around the area (hull shape). All points must be in sequence and the start point and the end point must be connected CR and the resulting area will be displayed. Do this for each section. The volume between 2 adjacent sections will be the average of the 2 values times the spacing. Now this might produce a slight error depending on the total hull shape but for all practical purposes the results will be just fine for what you want. If you have 3D available you can create a poly line of the hull shape, extrude the poly line to the section spacing and get the volume of the resulting soild with TOOLS INQUIRY MASS PROPERTIES, do that to 2 adjacent sections and then average the result.
Basically what you would be doing with CAD is what would be done with a planimeter in the days of old.

[Ken Hutchins]

Andy, what you need to do is find the area of each section, this can be done with TOOLS INQUIRY AREA then pic points around the area (hull shape). All points must be in sequence and the start point and the end point must be connected CR and the resulting area will be displayed. Do this for each section. The volume between 2 adjacent sections will be the average of the 2 values times the spacing. Now this might produce a slight error depending on the total hull shape but for all practical purposes the results will be just fine for what you want. If you have 3D available you can create a poly line of the hull shape, extrude the poly line to the section spacing and get the volume of the resulting soild with TOOLS INQUIRY MASS PROPERTIES, do that to 2 adjacent sections and then average the result.
Basically what you would be doing with CAD is what would be done with a planimeter in the days of old.

[AHall]

Sounds good Ken. I already have areas of all my sections using a planimeter. Now there is a piece of "voodo equipment" I traced each area a few times however, and got repeatable results. My hat is off to whomever invented that device.

I was hoping for an easy way to get a 3d model of the hull. (doesn't sound like it exists) Are there any shortcuts to get from feet,inches,eights on the plans into Autocad frendly units?

I will have to fool around with the spline commands and see where that gets me.

Thanks for your reply,
Andy Hall

[AHall]

Sounds good Ken. I already have areas of all my sections using a planimeter. Now there is a piece of "voodo equipment" I traced each area a few times however, and got repeatable results. My hat is off to whomever invented that device.

I was hoping for an easy way to get a 3d model of the hull. (doesn't sound like it exists) Are there any shortcuts to get from feet,inches,eights on the plans into Autocad frendly units?

I will have to fool around with the spline commands and see where that gets me.

Thanks for your reply,
Andy Hall

[AHall]

Sounds good Ken. I already have areas of all my sections using a planimeter. Now there is a piece of "voodo equipment" I traced each area a few times however, and got repeatable results. My hat is off to whomever invented that device.

I was hoping for an easy way to get a 3d model of the hull. (doesn't sound like it exists) Are there any shortcuts to get from feet,inches,eights on the plans into Autocad frendly units?

I will have to fool around with the spline commands and see where that gets me.

Thanks for your reply,
Andy Hall

[Bruce Taylor]

was hoping for an easy way to get a 3d model of the hull.

FREE!ship is fairly easy to learn (free download at www.freeship.org). 3D models can be exported to CAD as 3D or 2D .dxf files (face or polylines).

[Bruce Taylor]

was hoping for an easy way to get a 3d model of the hull.

FREE!ship is fairly easy to learn (free download at www.freeship.org). 3D models can be exported to CAD as 3D or 2D .dxf files (face or polylines).

[Bruce Taylor]

was hoping for an easy way to get a 3d model of the hull.

FREE!ship is fairly easy to learn (free download at www.freeship.org). 3D models can be exported to CAD as 3D or 2D .dxf files (face or polylines).

[gert]

actualy fairing lines on acad sucks.
I just drew all the stations out (on CNC) for Grey Seal full size on a sheet of black melamine (glue up table); there were 3 "bumps" on 3 stations.
I went back to my 19" monitor and they are not apparent.
Nothing a bendy stick won't fix [img]tongue.gif[/img]

[ 01-16-2006, 01:10 PM: Message edited by: gert ]

[gert]

actualy fairing lines on acad sucks.
I just drew all the stations out (on CNC) for Grey Seal full size on a sheet of black melamine (glue up table); there were 3 "bumps" on 3 stations.
I went back to my 19" monitor and they are not apparent.
Nothing a bendy stick won't fix [img]tongue.gif[/img]

[ 01-16-2006, 01:10 PM: Message edited by: gert ]

[gert]

actualy fairing lines on acad sucks.
I just drew all the stations out (on CNC) for Grey Seal full size on a sheet of black melamine (glue up table); there were 3 "bumps" on 3 stations.
I went back to my 19" monitor and they are not apparent.
Nothing a bendy stick won't fix [img]tongue.gif[/img]

[ 01-16-2006, 01:10 PM: Message edited by: gert ]

[Antonio Majer]

well, just to show what I have done in AutoCAD for my 14’ peapod, following Gardner’s offsets. In his books Gardner is always very careful, I didn’t need to fair the lines so much.

First I have drawn simple straight polylines, passing through each points of the offsets table; then I have “fitted” them via the Pedit/Fit command. I didn’t use the Pedit/Spline option, because a polyline doesn’t pass through those points any more after having been “splined”, while a “fitted” one does. For those who don’t know the problem, here there is a yellow straight polyline, a red arc-fit polyline and a magenta spline polyline (both gotten from the yellow one)



If one stretches the magenta spline, in order to make it pass through the old points, loses the original offsets (well, this is my experience, maybe I’m wrong).
Anyway it’s a matter of choice, in my opinion arc-fit polylines and spline-polylines aren’t so different when the curvature is small. To control the hull, I have drawn a mesh-surface between the longitudinal lines (edgesurf command), and then shaded it. If there are humps or dips on the hull surface, they can be found easily (via Orbit command) and corrected. Then I drew the sections of the planks at each station, plus some sections between the stations. Gardner gives a table of the widths of the planks at each station, hence I didn’t need to try for the best lining (well, for this particular boat, Gardner says it would have been better to line the first 2-3 planks slightly wider, but I preferred not to change anything).



When the plank sections are drawn, it is possible to join the sections of each plank with a surface. I decided to draw the outer face of the plank; probably it isn’t so important, the length difference between outer and inner face is minimal. I think in a caravel planked boat it’s mandatory the outer face, but I have never tried, by now - hope to loft a Whitehall this way, sooner or later. By exploding a mesh-surface, one gets 3D-faces, which cannot be exploded further and are not coplanar. It’s necessary to convert that mesh-surface into a wire frame of true lines, and to add a diagonal to each mesh to get coplanar figures, i.e. triangles; one has to trace those 3D-faces again, using simple lines (well, a lisp or VBA sub can do the job in a while). Then it’s possible to move each triangle from the XYZ space onto the XY plan via the Align command, and to get the development of the planks on the plan.



I plotted them in scale 1:1 clipping and hanging them on the molds for control (here you see a quick 1:10 half model too); I could build the planks all in one go.



AutoCAD is a wonderful software, last year I cross upgraded from AutoCAD2002 to ADT2005, an AutoCAD-based software for civil architecture/engineering, and I’m finding it astonishing.

[Antonio Majer]

well, just to show what I have done in AutoCAD for my 14’ peapod, following Gardner’s offsets. In his books Gardner is always very careful, I didn’t need to fair the lines so much.

First I have drawn simple straight polylines, passing through each points of the offsets table; then I have “fitted” them via the Pedit/Fit command. I didn’t use the Pedit/Spline option, because a polyline doesn’t pass through those points any more after having been “splined”, while a “fitted” one does. For those who don’t know the problem, here there is a yellow straight polyline, a red arc-fit polyline and a magenta spline polyline (both gotten from the yellow one)



If one stretches the magenta spline, in order to make it pass through the old points, loses the original offsets (well, this is my experience, maybe I’m wrong).
Anyway it’s a matter of choice, in my opinion arc-fit polylines and spline-polylines aren’t so different when the curvature is small. To control the hull, I have drawn a mesh-surface between the longitudinal lines (edgesurf command), and then shaded it. If there are humps or dips on the hull surface, they can be found easily (via Orbit command) and corrected. Then I drew the sections of the planks at each station, plus some sections between the stations. Gardner gives a table of the widths of the planks at each station, hence I didn’t need to try for the best lining (well, for this particular boat, Gardner says it would have been better to line the first 2-3 planks slightly wider, but I preferred not to change anything).



When the plank sections are drawn, it is possible to join the sections of each plank with a surface. I decided to draw the outer face of the plank; probably it isn’t so important, the length difference between outer and inner face is minimal. I think in a caravel planked boat it’s mandatory the outer face, but I have never tried, by now - hope to loft a Whitehall this way, sooner or later. By exploding a mesh-surface, one gets 3D-faces, which cannot be exploded further and are not coplanar. It’s necessary to convert that mesh-surface into a wire frame of true lines, and to add a diagonal to each mesh to get coplanar figures, i.e. triangles; one has to trace those 3D-faces again, using simple lines (well, a lisp or VBA sub can do the job in a while). Then it’s possible to move each triangle from the XYZ space onto the XY plan via the Align command, and to get the development of the planks on the plan.



I plotted them in scale 1:1 clipping and hanging them on the molds for control (here you see a quick 1:10 half model too); I could build the planks all in one go.



AutoCAD is a wonderful software, last year I cross upgraded from AutoCAD2002 to ADT2005, an AutoCAD-based software for civil architecture/engineering, and I’m finding it astonishing.

[Antonio Majer]

well, just to show what I have done in AutoCAD for my 14’ peapod, following Gardner’s offsets. In his books Gardner is always very careful, I didn’t need to fair the lines so much.

First I have drawn simple straight polylines, passing through each points of the offsets table; then I have “fitted” them via the Pedit/Fit command. I didn’t use the Pedit/Spline option, because a polyline doesn’t pass through those points any more after having been “splined”, while a “fitted” one does. For those who don’t know the problem, here there is a yellow straight polyline, a red arc-fit polyline and a magenta spline polyline (both gotten from the yellow one)



If one stretches the magenta spline, in order to make it pass through the old points, loses the original offsets (well, this is my experience, maybe I’m wrong).
Anyway it’s a matter of choice, in my opinion arc-fit polylines and spline-polylines aren’t so different when the curvature is small. To control the hull, I have drawn a mesh-surface between the longitudinal lines (edgesurf command), and then shaded it. If there are humps or dips on the hull surface, they can be found easily (via Orbit command) and corrected. Then I drew the sections of the planks at each station, plus some sections between the stations. Gardner gives a table of the widths of the planks at each station, hence I didn’t need to try for the best lining (well, for this particular boat, Gardner says it would have been better to line the first 2-3 planks slightly wider, but I preferred not to change anything).



When the plank sections are drawn, it is possible to join the sections of each plank with a surface. I decided to draw the outer face of the plank; probably it isn’t so important, the length difference between outer and inner face is minimal. I think in a caravel planked boat it’s mandatory the outer face, but I have never tried, by now - hope to loft a Whitehall this way, sooner or later. By exploding a mesh-surface, one gets 3D-faces, which cannot be exploded further and are not coplanar. It’s necessary to convert that mesh-surface into a wire frame of true lines, and to add a diagonal to each mesh to get coplanar figures, i.e. triangles; one has to trace those 3D-faces again, using simple lines (well, a lisp or VBA sub can do the job in a while). Then it’s possible to move each triangle from the XYZ space onto the XY plan via the Align command, and to get the development of the planks on the plan.



I plotted them in scale 1:1 clipping and hanging them on the molds for control (here you see a quick 1:10 half model too); I could build the planks all in one go.



AutoCAD is a wonderful software, last year I cross upgraded from AutoCAD2002 to ADT2005, an AutoCAD-based software for civil architecture/engineering, and I’m finding it astonishing.

[John Meachen]

I know a little about Autocad and it is obvious that Antonio is an expert.I would like to thank him for his excellent description of the processes he used.It would take a novice like me several months to learn to produce what has been documented and it would be a very valuable experience.This is the first and only account that I have seen in which the process of determining plank shape has been described.We can also see from the end result that it works.

[John Meachen]

I know a little about Autocad and it is obvious that Antonio is an expert.I would like to thank him for his excellent description of the processes he used.It would take a novice like me several months to learn to produce what has been documented and it would be a very valuable experience.This is the first and only account that I have seen in which the process of determining plank shape has been described.We can also see from the end result that it works.

[John Meachen]

I know a little about Autocad and it is obvious that Antonio is an expert.I would like to thank him for his excellent description of the processes he used.It would take a novice like me several months to learn to produce what has been documented and it would be a very valuable experience.This is the first and only account that I have seen in which the process of determining plank shape has been described.We can also see from the end result that it works.

[Ken Hutchins]

Nice work Antonio. [img]smile.gif[/img] I especially like the layouts for the planks. [img]smile.gif[/img]

[Ken Hutchins]

Nice work Antonio. [img]smile.gif[/img] I especially like the layouts for the planks. [img]smile.gif[/img]

[Ken Hutchins]

Nice work Antonio. [img]smile.gif[/img] I especially like the layouts for the planks. [img]smile.gif[/img]

[Dave Fleming]

I sure wish I knew what you guys is talkin' about?

That CAD stuff that Antonio posted looks mighty slick.

Antonio, you got the plank layout right from the CAD input? Did you make some mylar drawings/templates cut use in cutting them out?

[Dave Fleming]

I sure wish I knew what you guys is talkin' about?

That CAD stuff that Antonio posted looks mighty slick.

Antonio, you got the plank layout right from the CAD input? Did you make some mylar drawings/templates cut use in cutting them out?

[Dave Fleming]

I sure wish I knew what you guys is talkin' about?

That CAD stuff that Antonio posted looks mighty slick.

Antonio, you got the plank layout right from the CAD input? Did you make some mylar drawings/templates cut use in cutting them out?

[Antonio Majer]

Thank you so much. I have been using AutoCAD since 1990 (R10). Anyway I think that everybody can do this job, it isn’t true design, but lofting, isn’t it? I mean, Gardner is always clear and careful, I have only summed up his work. Dave: I plotted on paper (pretty heavy, 120g/m², sorry it’s to hard for me to convert it in lb/square feet), mylar costs lots of money. I was thinking that maybe one could “fix” the paper with a spray painting, but I never tried. Anyway it would be interesting to know the possible max dilatation of those strips of paper, I bet it is less then the accuracy of the execution.





Edit to add:
Dave, I think the more a software is useful, the more is potentially dangerous. One has simply to dominate his tools, otherwise they dominate him. Probably one needs more time to master a software then a pencil, which we start using when we are 2-3 years old, but it's only a matter of time. What should we say about the piano, then? probably the piano is the most tortuous and oddest machine ever invented, it takes 10 years and more to be learnt, the most of students leaves, but nevertheless there are people that can express the shades of their feeling through it. So I think the only rule is not to take anything for granted.

[ 01-21-2006, 09:51 AM: Message edited by: Antonio Majer ]

[Antonio Majer]

Thank you so much. I have been using AutoCAD since 1990 (R10). Anyway I think that everybody can do this job, it isn’t true design, but lofting, isn’t it? I mean, Gardner is always clear and careful, I have only summed up his work. Dave: I plotted on paper (pretty heavy, 120g/m², sorry it’s to hard for me to convert it in lb/square feet), mylar costs lots of money. I was thinking that maybe one could “fix” the paper with a spray painting, but I never tried. Anyway it would be interesting to know the possible max dilatation of those strips of paper, I bet it is less then the accuracy of the execution.





Edit to add:
Dave, I think the more a software is useful, the more is potentially dangerous. One has simply to dominate his tools, otherwise they dominate him. Probably one needs more time to master a software then a pencil, which we start using when we are 2-3 years old, but it's only a matter of time. What should we say about the piano, then? probably the piano is the most tortuous and oddest machine ever invented, it takes 10 years and more to be learnt, the most of students leaves, but nevertheless there are people that can express the shades of their feeling through it. So I think the only rule is not to take anything for granted.

[ 01-21-2006, 09:51 AM: Message edited by: Antonio Majer ]

[Antonio Majer]

Thank you so much. I have been using AutoCAD since 1990 (R10). Anyway I think that everybody can do this job, it isn’t true design, but lofting, isn’t it? I mean, Gardner is always clear and careful, I have only summed up his work. Dave: I plotted on paper (pretty heavy, 120g/m², sorry it’s to hard for me to convert it in lb/square feet), mylar costs lots of money. I was thinking that maybe one could “fix” the paper with a spray painting, but I never tried. Anyway it would be interesting to know the possible max dilatation of those strips of paper, I bet it is less then the accuracy of the execution.





Edit to add:
Dave, I think the more a software is useful, the more is potentially dangerous. One has simply to dominate his tools, otherwise they dominate him. Probably one needs more time to master a software then a pencil, which we start using when we are 2-3 years old, but it's only a matter of time. What should we say about the piano, then? probably the piano is the most tortuous and oddest machine ever invented, it takes 10 years and more to be learnt, the most of students leaves, but nevertheless there are people that can express the shades of their feeling through it. So I think the only rule is not to take anything for granted.

[ 01-21-2006, 09:51 AM: Message edited by: Antonio Majer ]

[Bruce Taylor]

Very impressive, Antonio! I especially like how you defined plank and rabbet bevels. Thanks for the the mini-tutorial.

[Bruce Taylor]

Very impressive, Antonio! I especially like how you defined plank and rabbet bevels. Thanks for the the mini-tutorial.

[Bruce Taylor]

Very impressive, Antonio! I especially like how you defined plank and rabbet bevels. Thanks for the the mini-tutorial.

[AHall]

Wow! Antonio: that is very impressive.
Thanks for showing us how it's done.

Cheers,
Andy Hall

[AHall]

Wow! Antonio: that is very impressive.
Thanks for showing us how it's done.

Cheers,
Andy Hall

[AHall]

Wow! Antonio: that is very impressive.
Thanks for showing us how it's done.

Cheers,
Andy Hall

[bainbridgeisland]

Originally posted by AHall:
Wow! Antonio: that is very impressive.
Thanks for showing us how it's done.

Cheers,
Andy Hall

I too think Antonio did a great job but I can't help but ask why? As an AutoCAD user at my work, I recognize how time consuming it is to do what Antonio did. Regular old lofting by hand would have been less time consuming.

In my opinion, computer lofting is only efficient if the electronic model is already in your computer. Further, AutoCAD is not a very good program for lofting. I use Rhinoceros 3d and it works O.K. with the right plug-ins. It is far, far faster to loft with it that with AutoCAD. Never the less, lofting by hand would still be faster than creating an electronic model from offsets and then lofting it electronically.

This is somewhat of an ongoing pet peeve of mine. Having lofted professionally both by hand and electronically, I just do not see why everyone wants electronic lofting. It isn't any better than hand lofting and commonly takes longer. The accuracy of the finished product is controlled far more by the construction tolerances than by the lofting tolerances. It only saves time if the plans are in electronic format to begin with.

David Mancebo

[bainbridgeisland]

Originally posted by AHall:
Wow! Antonio: that is very impressive.
Thanks for showing us how it's done.

Cheers,
Andy Hall

I too think Antonio did a great job but I can't help but ask why? As an AutoCAD user at my work, I recognize how time consuming it is to do what Antonio did. Regular old lofting by hand would have been less time consuming.

In my opinion, computer lofting is only efficient if the electronic model is already in your computer. Further, AutoCAD is not a very good program for lofting. I use Rhinoceros 3d and it works O.K. with the right plug-ins. It is far, far faster to loft with it that with AutoCAD. Never the less, lofting by hand would still be faster than creating an electronic model from offsets and then lofting it electronically.

This is somewhat of an ongoing pet peeve of mine. Having lofted professionally both by hand and electronically, I just do not see why everyone wants electronic lofting. It isn't any better than hand lofting and commonly takes longer. The accuracy of the finished product is controlled far more by the construction tolerances than by the lofting tolerances. It only saves time if the plans are in electronic format to begin with.

David Mancebo