This video shows a few different spindle mounted drag knives, about 25 minutes in are a couple that he made himself and that style seems like a great idea to me, is anything like that commercially available?
https://youtu.be/FxsfDxR8CD4?feature=shared&t=1514
Not spindle mounted, but the (sold out) one Ryan has in the store worked amazingly well for $10. Best $10 I spent on my MPCNC.
I really like the idea of a drag knife that doesn’t require any addition fixtures and also doesn’t require require removing the spindle but any event, I will be getting a drag knife of some description for my machine, maybe this one, seems like a promising candidate, https://shop.carbide3d.com/products/stingray-vinyl-cutter
The good thing about using the one Tuco has linked is the mount itself acts as a spring.
The Carbide 3D one is basically a mount to hold that type of knife in a spindle.
Yes I see that. My worry would be if you get the depth wrong by the tiniest amount (10th of a mm) it’s going to put too much pressure on the tip of a very brittle blade and snap it.
The horizontal arms of the mount act like leaf springs to help prevent that. There is another design that is spindle mounted that uses utility knife blades which are a bit more robust and very cheap but I think the mount was expensive.
I agree, at least with respect to the ones in the video from my first post but take a closer look at the Carbide ones, their design includes a spring to account for that.