Hi, I made this cutter a couple of years ago now, it's based on the vinyl-cutter type of idea but uses standard scalpel blades. and is good for thicker - soft materials.
I've had brilliant results cutting rubber 1mm ish, thin acetate film, 3mm or so expanded neoprene and soft foam (that in straight lines only) up to 10mm - . there is no weighting or spring pressure involved just set the Z to cut into a waste plastic sheet underneath a small amount.
Theres a couple of small ball bearings in there so that the blade can rotate very freely.
The dimples you may notice were a latter addition along with a small block containing a 2.5mm spring loaded ball. the idea was to prevent the blade moving by 'presetting' the blade (having fixed the spindle rotation) and only traversing the machine in the one cutting direction. strips of say rubber could be cut with bang on width. turn the blade by hand and then cut the strips to length. forget the block addition if you're after fancy cnc profiles
There is a tempory spray adhesive which I found very helpful to keep thin sheet material in place (spray the waste sheet not the m/c bed!) - quite a few sheets can be held in place before the need of a re-spray much better than the blade tip draging through double sided tape you can easily get a very sticky knife that way.
It dosn;t really like 90 deg sharp turns, so program a courner radius in relation to the thickness of the mat'l being cut for say 1mm rubber. maybe R2 and R3mm will be needed for the 3mm neoprene. this is important!
Note that the blade 'likes' to follow the previous cut in your waste so make allowance for that.
Add a bit of 'approach' to the tool path as it starts the cut so that the blade has time and space to swivel when entering the cut - if you can
The blade clamping shown is a little crude!! a small stepped block is called for here in my design. you need to allow the position of the blade to be altered quite a lot for the different thicknesses a scribed line accross the center line helps in alignment of the blade point
leaving the full length of blade in place reassures you that the cutter is turning ok. you can see any 'wobble'
Don't try wood with a grain cos the cutter would just follow the grain !!
I've used mine on a bridgeport EZtrack which is just 2 axis (plus me) hence the shank size being a bit large 16mm shown here.
brilliant for rubber gaskets - use a sharpened tube for bolt holes
If you're wanting to cut thin vinyl then the thread 'Homemade vinyl cutter' by tauscnc is the way to go, he describes a great weighted cutter that will do all the tight rads for you in the thin stuff, his design will also allow for a bed that is not flat.
Don't forget - don't start that spindle - unplug it its amazing sometimes how the hand reaches (in my case) for the spindle start