Light Aircraft Association

Hello,

Just wondering if any forum members have successfully converted blueprints into AutoCAD files or similar through scanning them and converting them into .DWG files to then use for water jet cutting of steel fittings? I'm at the stage where I have a lot of 4130 brackets to make and being able to have the blanks precision cut would save a lot of time. Clearly the source documents would need to be dimensionally accurate with bend allowance where appropriate to enable the parts to be produced correctly.

Thanks

Chris

I've tried it in the past and found that it was quicker and easier to redraw the whole diagram or just the parts you want in 3D CAD.
Never assume a drawing is dimensionally accurate, most aren't.

Chris,

I'm pretty sure what you suggest is not possible.

Sure, you can use a scan as a background image in AutoCAD, but there will be no vector information to work with, it's just a scan, a raster image and hardly reliable for precision cutting.

Your point about bend allowances is interesting, though for thin metal parts perhaps not significant, but where, for the purposes of calculation, would you assume the neutral axis would lie through a bend? Half way? One third/two thirds?

I think Ian is right though. Redraw the parts you need based on the dimensions stated on the drawings.

I have reams of paper plans, some full size, for the Chasle Tourbillon - a single seat plywood covered aircraft. Too late in life now to build (it used to be on the PFA approved designs listing) but was advised not to take dimensions from them due to paper shrinkage etc.
One of these was in build in the early eighties but was passed on for completion by another builder but I don’t think it ever appeared on the register.

Thank you for the replies, I thought this would be probably a difficult thing to do. Having previously checked some of the parts against those shown in the drawings their dimensional accuracy isn't perhaps as good as it ought to be, especially when compared to the original component, so there'd need to be a way to 'edit' the scanned drawing into a suitable format, which would take longer to do than simply cutting out the parts with a band saw and finishing them by hand.

I started to do something similar using my plans for the Marquart Charger. I would recommend something like Inventor or Solidworks rather than AutoCAD but as said you will need to redraw the items. I believe you can get a free Solidworks licence with an EAA membership.

It is possible to convert PDF to AutoCAD but this has to be done from the original PDF that still holds the vector information. Once it is scanned to PDF then it basically just becomes an image so can only be traced.

Mike is correct, EAA membershio does come with a free Solidworks licence. Solidworks and Inventor are top level CAD systems and you can do splendid work once you've become accustomed to their operation but that's not a trivial learning process. I'm an EAA member but I use Inventor because that's the program I used at work many moons ago - and I still refer to the help files. They are really for professional use and, if purchased, extremely expensive. If all you need is a set of CAD files to get flat plates water jet cut then a simple 2D program would suffice and you can probably get one free on the web. You would have to work out the bend allowances and such yourself but that would be quicker than learning to use Inventor! RS have a free CAD program in their DesignSpark series which may be worth a look.

Jim

If it is just 2D drawings you are after, I've had good results from Draftsight, the free CAD package from Dassault.

Tony Razzell