Lofting article

[Guest]

Hi all. As I was looking into drafting manually frames, I read this article. It is very interesting and the lofts man was a very special techical person... 

https://www.theloftsman.com/lofting-design

 

the spaces used were huge!  One does wonder how the huge frames were lofted for the 74's. And ships like them.  The wood was huge!

 

enjoy

guy

[Roger Pellett]

Lofting was required for all ships including 600- 1000ft steel hulled vessels prior to the development in the late 1960’s or 1970’s of CAD systems linked to robotic plate burning equipment.  Loftsmen were highly skilled and able to “fold” designs on the mould loft floor to save space.

 

Roger

[shipman]

A sound treatise of the subject is 'Lofting' by Allan H. Vaitses.

[Guest]

Hello Shipman, thank you.  I will look into that book.  I have Chapmans book on boat building and small craft.

I will be manually drafting my own drawings for a ship.  I do plan a log.  It has been many years since I sat at a table.

I have been looking through things to see how others have done this.  I am finding pieces and parts but nothing showing or descrribing how they lofted and created drawings for a build..  I am 66.  My dad was a civil engineer and did all his own drawings and I have most of his drafting tools.. some from his great uncle.. anyway. still hunting. 

 

I found the article on lofting a good read.. now to do it on paper in 1/4"=1foot.. 1779 style

 

Thanks!

Guy

 

[allanyed]

Hi Guy

I am not sure if this will help but take a look in the Articles data base here at MSW in the Plans and Research section and see Wayne Kempson's treatise.  While it's set up for CAD, it may still be useful for hand drafting in many respects.

Allan

 

Edited October 17, 2022 by allanyed

[Roger Pellett]

Guy,

 

in it’s simplest terms, lofting is nothing more than drawing a conventional lines drawing, then lifting off details for making patterns.  Some of these patterns like those for square frames can be traced directly from the lines drawing.  Others like cant frames require special projections for “true views.”

 

I still hand draw lines drawings.  These do require some special tools:

 

A quality straight edge, at least as long as the drawing that you intend to draw.

 

A large drafting triangle

 

One or more splines, 3/16” approx cross section for long curves.  I rip mine from straight grained spruce limber.

 

Drafting weights to hold down the splines.  These are expensive to buy but you could rig up some homemade ones.

 

Ships curves; these are specialized “French Curves”.  Used sets can be found on EBay, and new sets of 6 or so common ones are available there too.

 

I also have a rotary electric eraser.  I find this to be necessary for completely erasing.  By its nature drawing a set of lines requires a lot of erasing.

 

I make my drawings in pencil and then trace them in ink.  Office supply stores sell disposable fine tipped technical illustration pens that work well.  I use Frosted Mylar drafting film for both the pencil and ink drafts.  Old time draftsmen were experts at making crisp, dark, pencil lines that reproduced well, but I don’t have that skill. An inked drawing reproduces well.  I like to make these drawings twice as large as the intended model scale.  This allows better interpretation of subtle details.  I then have a half sized contact print of the inked drawing made by an architectural printing company.

 

I would also suggest that you visit the WoodenBook Store online.  They offer a selection of lofting books.  In particular they sell a book on half models that discusses lines drawings.

 

Roger,

[Pete Jaquith]

After graduating from Webb Institute of Naval Architecture and Marine Engineering, I joined Bath Iron Works in Bath, ME.  My 1st year included an apprenticeship in the "full scale" and "1/10th scale" mold lofts.  Very enjoyable time and I learned a lot re structural design, material routing, and design for production.  Later in my career, I ran the mold loft at BIW and oversaw the transition to 3D CAD.  Today, most of the traditional loft functions are preformed near automatically using artificial intelligence (AI) and the 3D CAD design product model.  Recently I have assisted the US Navy and warship builders with recommendations re modern 3D CAD Product Model design systems.

 

For model building, I prefer to draw my own lines using ship's curves, a tapered pine batten, and lead batten weights from my four years at Webb.

 

 

[Guest]

Thanks a lot for the help here! Pete, Roger, Allan! I found a useable vemco vtrack and used board to set up on an existing table.  I vyko(?) cover as it had come loose.. the guy I got it from locally only wanted the oak table this was mounted on... heh.. I wanted the other.

 

I will be creating a log once I determine what I am going to build (pictures posted then).  I have a lot of old drafting tools (many inkers, but I wont use these). I will be building 1/4" scale.. so its going to be bigger.  The scales on the vemco came with 1/4" and 1/2" scales which will be nice.   I could go the CAD route (Im an IT guy.. but use Linux almost exclusively) I have the QCAD pro for simple things.  Gimp and Inkscape for PDF stuff and measuring and best of all a great local printer that will print things for me from any number of formats. 

I will have to re-draft much though and that will be a fun thing for me. 

 

I have a great friend in the southeast that is helping me a lot.. 🙂

 

Thanks again!

Guy

[Roger Pellett]

I suggest that you check the two scales on your drafting machine to ensure that they are exactly square with one another.  The accuracy of your lofting depends on your ability to draw a grid with body plan sections exactly square to waterlines.

 

Roger 

[jud]

Throw that thing out, and obtain a good Parallel Rule. Preferred them over drafting machines for a long time. 

[Guest]

Hi rodger. That's the first thing I checked. They are square using my triangles and engineering squares. 

 

Jud,  this was local for me. I have a smaller parallel board. Nothing like yours. I am on a limited budget and driving distance after my two right cerebral strokes. Doing what I can with what I have. 

 

Guy

[jud]

49 minutes ago, Treebeard said:

Guy, "Doing what I can with what I have." Understand, only had one stroke that I am aware of, it cost me the sight in the right eye. 

The drafting table photo is off the net, mine is a solid core door from a hospital that was torn down years ago, pad like yours and hinged with a piano hinge to a surplus steel desk, setting on blocks, tilt is adjusted by sliding a 4 X 4 between the desktop and door, right now it is sitting flat and used as a desktop, went to CAD for my drafting some time ago. Also make do with what I have or can put together.

 

 

 

[Boccherini]

Guy,

Roger's comment above covers it well.

You could try and obtain a copy of Underhill's "Plank On Frame Vol 1". He runs through the whole process in an easily understandable and encouraging fashion. That book was my bible whilst lofting the frames for my "Harriet McGregor". It has been a constant source of inspiration/construction techniques since.

I borrowed (budgetary constraints) a drawing desk similar to the one you have; a couple of set squares, a set of French Curves, a 600mm flexible curve, a bunch of pencils and good quality erasers completed the kit. It worked out well.

My drafting background: 5 years at high school 45 years ago.

Take your time and keep the pencils sharp. You'll be fine.

 

Regards,

Grant.

Edited October 21, 2022 by Boccherini