How do you accurately measure an airsoft gun?

[Crafter]

Hello fellow builders,

I'm currently working on a project where I want to build a prop gun around an existing airsoft gun to have it shoot BBs once finished. There are no detailed blueprints of the toy around and I already checked if the airsoft variant got the same dimensions as the original gun. Of course, it has not, so I have to measure it myself. Since I want to design the parts that connect the airsoft to the final project in Fusion 360 to print them later, I need fairly accurate results.

How do you approach something like this? I spent an evening with a ruler and a calliper to get all the geometrically simple parts right (slide length and width, overall height and width, the sights, etc). But I'm having a hard time figuring how to deal with radii and curves, for example on the grip or the trigger housing, where my prop-parts most likely will need to connect to the airsoft. I thought about taking pictures from the sides, top/bottom and front/back, scaling it to the measures I already know and making a draft from there, but taking perspective and lense distortion into account, I'm not sure if I will really get good results?

I'm thankfull for any hint, take care,

Crafter

 

[Strikerkc]

so, so much of an airsoft gun is just slapped on stuff to make it look right, that you may actually be better off replacing parts of the airsoft gun. What airsoft gun is it you're messing with, we can probably tell you what parts can straight up go/be replaced (including the grip, in all likelihood).

 

[itsgreg]

I take a picture of of the gun side on ( I scan it if it's a handgun). Import it into my cad package, scale it & model on top of the image. You do get a bit of distortion but it's not too bad.
You can also print a drawing of your parts to scale before you 3d print/cnc them and check the sizes against the gun before you commit to manufacturing.

 

[Crafter]

so, so much of an airsoft gun is just slapped on stuff to make it look right, that you may actually be better off replacing parts of the airsoft gun. What airsoft gun is it you're messing with, we can probably tell you what parts can straight up go/be replaced (including the grip, in all likelihood).

Hi Strikerkc
I already took it apart to check what I can get rid off. It's a Umarex Glock 17 gas blowback where pretty much all the internals are attached to the grip / lower, wich I'm planning to keep / cover with cast parts to change the look.

It's not this specific model that is causing me a headache, I need to learn the right way to measure real life items to transfer it into the digital world, like you often have to do in prop building, especially when there are parts you could identify and know the size of.

 

[Crafter]

itsgreg,

thanks, I like the idea of printing it to check the size.

 

[Strikerkc]

For a smaller airsoft like that, you might be able to do one of those "at home" 3D scans that uses an rotating base, and a free photo analyzer. The rotating base and stands can be 3D printed.

That would give you an actual 3D model of the grip or other parts to work around.

 

[Friendly flyer]

Depending on what aircraft gun you're after, there might be scale plans or even 3D models available out there.

 

[laellee]

You've gotta be careful with a lot of the gun 3d models out there, a lot of them have themselves been worked up off of inaccurate schematics, so the models still won't give you a whole lot of help. I say this from personal experience, both working with inaccurate models and also having to go through the headache of building a model from scratch off of caliper measurements lol...

Two things that may help: Scan the gun on a regular printer/copier/scanner; you will get a little distortion but it gives a great accurate silhouette at correct scale.
Secondly, get yourself Agisoft Photoscan (you should be able to download it free from the Agisoft site). Take 20-30 pictures of the gun from all angles (there are vids on youtube as well for directions), upload them to Agisoft, and then they use their processing power to generate a 3d model from the shots and get it back to you (takes about a day). The scans are not going to be pristine, but I've been able to then use the scan as a base to model fresh geometry over. It's not fool-proof, but it's gotten me close-enough before.