Ouch!
At age 21, a couple of weeks before beginning Medical Technology school, a recriprocating blade, similar to this, went through my left thumb almost to the first joint. It was split through. Was helping install a new blade with another farm hand. Didn't know how many pieces of thmb I would see when I removed my now ruined gloves. Learned to perform phlebotomy without the use of this thumb. Healed pretty well, only a slight numbness on one side. I don't recommend this way of cutting your fingers.