A step towards a drag knife for the CNC. More a proof of concept than a prototype at this point, as even a decent quality hardwood cracked in several places when I was assembling it. (The first attempt with cheap Home Depot white wood was even worse.) It was cut on the CNC, based off a design I found online, the aluminum precursor of the 3-D printed version that Travis posted a link to in another thread.
I’m not clear on why the design uses two bearings rather than one; my best guess is just to provide a longer length of constrained shaft for stability. Amazon sold those bearings in packs of two anyway, but I’ve been looking for ways to simplify the design.
It still needs a few tweaks, but I’m considering these options going forward:
- Cut it on the CNC out of an appropriate hard plastic.
- Cut it on the CNC out of aluminum. It will take a thicker block than would usually be cut on the CNC, but it should still be feasible if I pay attention to the details of spindle speed and cut rates. And I understand those issues much better with aluminum than I do with the various plastic options.
- Cut it on the manual mill and lathe. This was my original intention, which is why I worked to simplify it, but no matter what, the key features are at 37.48 degrees to the horizontal. I see some possible ways to set the cuts up using a blade as a guide, but it will definitely be tricky.
- Learn to use the Tormach already, which I should really do since my focus as a new steward will be the machine shop. But that takes my time, my money, and Eric’s time, all of which are in short supply right now.
(Note that 3D printing it is not a good option. I know little about doing so, so the issue of paying for and taking classes remains. And apparently the 3D-printed versions have not worked well. Depending on what plastic they used, they’ve either bent or broken.)
Aluminum is clearly the way to go, but I’ll have to think more about how.