For Creative and Quantitative People

[CatBuilder]

I am getting ready to cut out my bulkheads. I'm too lazy (and want to go too fast) to go and get large print outs done to trace out.

Instead, I'd like to transfer the bulkhead patterns to mylar (or just use the .dwg files) and just quickly follow a projected line on the bulkhead sheets for a fast, simple cut out process.

I'm looking to do a dimensionally accurate projection.

Anyone have any thoughts on this and what will be the best way to do a dimensionally accurate projection?

Scale doesn't matter - I'll take care of scale by using some known distances on the projection.

[nukisen]

Why not let someone cut out chablons for you with a cnc cutting machine. waterjet cutting machines are also able to cut them out for you in a soft easy quite thin material it will go very fast.

[CatBuilder]

It's 12MM Okoume, which is currently at my boat shed. I'm not interested in paying for CNC or transporting material elsewhere.

[bntii]

Originally Posted by CatBuilder

I am getting ready to cut out my bulkheads. I'm too lazy (and want to go too fast) to go and get large print outs done to trace out.

Instead, I'd like to transfer the bulkhead patterns to mylar (or just use the .dwg files) and just quickly follow a projected line on the bulkhead sheets for a fast, simple cut out process.

I'm looking to do a dimensionally accurate projection.

Anyone have any thoughts on this and what will be the best way to do a dimensionally accurate projection?

Scale doesn't matter - I'll take care of scale by using some known distances on the projection.

If you need fast for the least effort a real pattern buys both.

My large roll feed plotter makes short work of patterns directly from .dwg files...

How many bulkheads?
Zip me one of the files and I will check to see how plotter ready it is:

trboatworks @ gmail.com

[nukisen]

Thats a very cheap and also a perfect solution.
Just see what this forum is able to do.

[nukisen]

I wonder why it puts double posts when answering from my cellphone?

[CatBuilder]

nukisen: My phone replies do the same thing, but only on this forum. Strange, isn't it?

One of the bulkhead files has been sent, Bntii. Thanks for having a look.

[Lurvio]

If you have the drawing in a cad-format, you could place a rectangle the size of your plywood to the picture and start measuring points in coordinates X and Y. I used this method to loft the stem lines to a plywood for my little boat project. I had small enough radiuses to use center point and end points and use a compass to draw the line. Enough points (4 to 8 inches apart) will give you 'good enough' accuracy.


Lurvio

[upchurchmr]

Sorry I don't understand the problem. Are you talking about projecting as in a projection TV? At work we have some people putting drawings into a power point format, projecting onto a work surface in order to accurately locate drilling points for attaching brackets. The only thing I know they do is include a dimensioned line vertically and horizontally to check the projection scale. There must be more but I have only heard about the process.

Marc

[CatBuilder]

Exactly!

Yes. I have print outs (not to scale) and some .dxf files. (not DWG)

I was thinking of skipping a whole lot of steps by putting my plywood sheet up in a vertical manner and possibly using something like this to project the image directly onto the sheet so I could just start cutting it out:



Seems a lot easier then going through a bunch of printing BS or tracing things out with carbon paper.

Originally Posted by upchurchmr

Sorry I don't understand the problem. Are you talking about projecting as in a projection TV? At work we have some people putting drawings into a power point format, projecting onto a work surface in order to accurately locate drilling points for attaching brackets. The only thing I know they do is include a dimensioned line vertically and horizontally to check the projection scale. There must be more but I have only heard about the process.

Marc

[hoytedow]

Michaelangelo did it by punching holes in a sheet of paper along the lines and shining a candle behind it. He then marked the dots on the wall and connected them. I think it was Michaelangelo. I could be mistaken.

[hoytedow]

This veers off-topic slightly but I thought you might find it interesting.: http://www.diatrope.com/stork/Stork11.pdf

[CatBuilder]

Originally Posted by hoytedow

Michaelangelo did it by punching holes in a sheet of paper along the lines and shining a candle behind it. He then marked the dots on the wall and connected them. I think it was Michaelangelo. I could be mistaken.

That's the kind of stuff... there we go!

I may try that as well, but with a little more than a candle.

[DCockey]

Anyone planning on using a projection system should check for distortion. Prepare a simple square grid and project it. The projected lines should be straight, parallel and equal distances apart.

If the lines are not parallel but are straight then the projecter isn't properly aligned with the surface you are projecting on.

If the lines are curved, particularly lines near the edges, then the surface you are projecting on isn't flat and/or the lens has some distortion. I would not be surprised if a lenses in a projection systems has some distortion, particularly a zoom lens.

If the lines are straight and parallel but the lines in one direction are different distance apart than the lines in the other direction then there is a problem before the lens. If a printed grid is being projected then possibly the printer isn't perfect. If projector is the type which hooks directly to a computer then the projector image system isn't perfect.

How much you should be concerned about this depends on how accurate the enlargements need to be.

[CatBuilder]

Yes, Dc. Agreed. That is what I asked about in the first post.