Knife handles

[antennasDIY]

I want to take a knife I have and make wooden handles for it. I know folks do this all the time and I have been looking around. I just wonder if anyone can tell me why my knife scan picture doesn't match up with what I measure. I have attached a pic of it here. Is it picture resolution or what is going on?? It should match shouldn't it?

[RoutnAbout]

It's rare that your scan will come out 1 to 1 ratio.
Your real close to what I think your after.

Use (N)ode edit mode and move the nodes around until they fit like you want them to.
While in node mode try to get rid of as many nodes as possible.
Once the vectors are to your liking. Group all vectors and then use the scaling feature to chance the vectors to the actual over all width and height. After doing so, you might have to ungroup and recheck hole sizes and dimensions to be sure.

[antennasDIY]

Ok sounds good. I'll go with what I measure and not the scan I suppose. My first try so I'll do it in soft wood first! Thanks!!

[Ms Wolffie]

What I do with a scanned picture is to draw a rectangle the size I need, then I drag the sizing handles as close to the rectangle's sides as I can.
Then the model comes out the right size.

[BOOMER52]

Attempting to scan a 3D object on a flat bed scanner will introduce error of varying degree depending on the distance of the landmarks from the scan head as it passes beneath. The better way to scan those scales is to remove them and scan the flat back side OR even scanning the knife tang to locate those critical screw attachment landmarks.

Once I have the scan image I import it and run it through my CAD application for landmark placement and profile tracing. I then create an EPS file and print that 1:1. I then place the scale OR tang over the printout to check alignment. It's a wash, rinse, repeat activity until you nail it.

Steve

[antennasDIY]

Thanks Boomer, sounds good. I'll try and scan the handles on the flat side. Should have less error.
Good to know it's a try and test method. Thanks.

[dldecker]

I usually place a ruler with fine marks next to what I am scanning, then import it Aspire(add a 1 inch square )and match it up with the ruler to make it the right size

[BOOMER52]

The inclusion of a machinist ruler in the scan is great idea... any of the lower cost desktop flatbed scanners do introduce a small parallax error and tend to GROW an image ever so slightly.

Another method I use in some situations is to trace the scale/liner/tang onto a sheet of paper using a very sharp pencil. I trace the outline profile and all critical landmarks such as screw/rivet holes, pivot holes for folders, and internal pocketing if required. The sharpness of the pencil tip and angle you trace the subject will determine the degree of oversize of the drawn image as you are marking outside or inside of the actual shape. A dull pencil will mark a thicker line further from the actual profile shape.

I then scan the hand traced drawing to get it into a digital PNG file to import for tracing. I've found PNG is a higher fidelity image file for manipulation in most CAD applications. JPEG can introduce too many artifacts and jaggies to be useful.

[antennasDIY]

Also great ideas. I will try them both, thanks!!

[gordread]

What if you were to take the handle off of the knife and scan the back? It would be more or less flat wouldn't it? I guess that wouldn't really fix the problem of scaling if the scanner is changing the size of the image.