Advice Wanted - Scanning Sideframes and Getting 1:1 Results

[brw0513]

Hi all. I'm after some advice please.

I have a sideframe that I want to use as a starting point for a project. The process I've learned from others is to scan the sideframe into a raster format, then import that image into AutoCAD2007. The boundaries, pockets, slots and holes can then be superimposed within CAD. Changes made, G-code tool paths created and new part produced.

My problem is the CAD drawing is slighter larger than the original and it gets stretched further in the X direction than it does in the Y direction. A simple re-scaling won't correct the error.

I guess the scanning process introduced the errors. But what have others found and done?

I thought I'd ask here before looking for an over-complicated solution.

Good advice appreciated.

Thanks.

[C_M_H]

I hate it when that happens. But have not had that problem in Autocad lately, maybe it's an older version issue.

First off, did you scan the source? Did you crop in the scanner software, or apply a crop afterwards? If you are cropping in the scanner software, did you crop it square?

Did you use healthy resolution ( DPI )? Like 300 or 150 minimum?

Are you sure you found every import option there is?

I've run onto this problem in a number of software packages, sometimes it's the brute force technique that gets me there. There are 2 things I do to make adjusting possible;

1. Put a 6" rule on the scanner as well the object. This way I have a clean reference for what scale the piece should be.

2. In cases like yours, where it's a non-uniform scale issue, I'll place a piece of engineer's grid paper behind the part, or if it's not flat enough, cut a pocket out so that the paper sits flat on the scanner.

From there it's a matter of entering scale values until you hit 6" mark spot on, both axis.

Hope this helps, I know how frustrating this is.

[brw0513]

CMH,

Thanks for the reply. I did scan the image myself at 300DPI. No cropping applied.

The 6" scale, or grip paper is a good idea. I'll give it a try.

I may have another option too. IrfanView software does image scaling and allows differnt values in both X and Y directions.

[brw0513]

I've tried the scanning process again now I've had success. Don't really understand why, but I'm not complaining!

[Khal]

Seems your problem is solved however, being a CAD Monkey for a living, I can tell you that if you have something in AutoCAD, you can type "b" and turn it into a block.

During the block creation process (basically just giving it a name and then selecting the objects), there is a check box labelled 'Scale uniformly'.

If you leave this unchecked, after you've created a block from the object(s) you select that block and scale it independently in the X, Y & Z axis, in "Properties".

[Esstee]

Originally Posted by brw0513

Hi all. I'm after some advice please.

I have a sideframe that I want to use as a starting point for a project. The process I've learned from others is to scan the sideframe into a raster format, then import that image into AutoCAD2007. The boundaries, pockets, slots and holes can then be superimposed within CAD. Changes made, G-code tool paths created and new part produced.

My problem is the CAD drawing is slighter larger than the original and it gets stretched further in the X direction than it does in the Y direction. A simple re-scaling won't correct the error.

I guess the scanning process introduced the errors. But what have others found and done?

I thought I'd ask here before looking for an over-complicated solution.

Good advice appreciated.

Thanks.

By today's standard, I'd have to say AutoCAD sucks.
Try downloading something friendlier to work with such as; Innovate (trial) and you'll have a working part made in no time. For what it's worth, rotoscoping is fine to get a headstart at which point it won't take more than a few mins. to adjust your final part.

PS. 3D modeling really is a blessing to work in in cases such as these.

Hope this helps.

[brw0513]

Originally Posted by Khal

Seems your problem is solved however, being a CAD Monkey for a living, I can tell you that if you have something in AutoCAD, you can type "b" and turn it into a block.

During the block creation process (basically just giving it a name and then selecting the objects), there is a check box labelled 'Scale uniformly'.

If you leave this unchecked, after you've created a block from the object(s) you select that block and scale it independently in the X, Y & Z axis, in "Properties".

Great tip! Thanks

[R.C. man]

SolidWorks work good for me, I just get a rough measurement, open a sketch, import a pic, give in the measurements for a given distance, and solidworks gives me all I need, Kinda like scanning, but in mydays, we didnt have a scanner you could hold in your hand.
But to help ya, hold the scanner 90deg. to your work piece, otherwize, youll get a shadow that your program will decipher as a hole or an artifact. Kinda like a shadow on a pic with a Digicam.

I made this for my own heli. The frame sides from Ti