A serviceable printable hobby knife.

Update: 09/12/2018

I've uploaded the individual parts for those who need to print a part separately. They are the exact same models though, so you still only need the "Blade_Holder_V20-_No11_Hobby_Knife.stl and "Cap_and_Handle_V20-_No11_Hobby_Knife.stl" files for a full knife.

Update: 06/14/2017

I'm replacing the original files with this V2 version. The design has been modified to strengthen the fingers that hold the blade. Much more robust now. Also, I scrapped the cap design I had originally. The original cap design forced you to orient the blade a certain way to get the blade in. This new design can be put on in any orientation. The only drawback is that it doesn't socket onto the tip of the handle when not in use, but honestly I found that I never used that feature anyway (I doubt anyone else did either - it was just cumbersome). Note: the cap will be pretty tight when you first put it on, so BEFORE you put a blade in (for safety), screw on the collet as normal and then snap the cap on and off a few times. It will clearance itself and be a lot easier to use.

Update: 12/10/2016

I modified the cap design and how it snaps onto the handle (due to some feedback that the cap was cracking on some prints). This new version has no slots on the side, which is where the crack was forming. I also moved the retention dots down on the base so now instead of the cap snapping onto those, it uses those dots as a "stop". It is now totally an interference fit and uses the layer ridges as the friction surface for retention. I did a test of taking the new cap on and off about 200 times and after the first few, it didn't seem to develop any additional slop. Feedback appreciated!

I wanted a bunch of spare hobby knife handles to distribute through the various places in my shop, but none of the printable versions I found were very robust and tended to let the blade slip pretty badly under normal use (for me that is cutting foam board, balsa, and other lightweight material).

This design grips the blade from both the sides and the edge and has a detent inside the collet to help keep the blade from slipping out. Also, the collet shaft is thick enough so that there is a decreased danger of the knife breaking when you are applying pressure.

I also wanted it to be quick to make in its most basic form, so it is designed so that you can use a 3/8" dowel as a handle.

There is also printable handle which is designed to decrease the propensity for the knife to roll around, and also an optional cap. The cap sockets onto the end of the handle when not in use.

I've had a couple of people mention the "gap" between the top portion that compresses the collet and the collet base: that is actually kind of needed. As the knife ages and things loosen up over time, that space will take up the slack. Over time you'll be able to screw the top part on tighter and tighter and without that space, you'd bottom out the top portion pretty quick.

Obviously this is a printed hobby knife, so don't go bananas with it. It's strong, but not as strong metal one. Be careful.