Low-profile two-piece vises for the CNC router

I replaced the little 5-axis mill with a router recently, and needed a low-profile vise system for holding large workpieces. I’ve heard good things about the SMW Mod Vise, but they are designed for fixture plates, not 100mm pitch t-slots like the router has. And 3 sets to cover the hole table with serrated inserts would be pretty pricey.

I came up with a simple design that uses these Mitee-bite Talon Grip style inserts on the fixed jaw, and Pitbull-style inserts on the moving jaw. Parts are clamped by pushing the moving jaw up against the stock, tightening down the t-slot bolts, and then tightening down the Pitbull clamps to grab the stock.

I made the parts from an ebay pile of 4140 HT (pre-hardened to ~32HRC). Op 1 was decking off one side and adding some M8 taps so I could bolt the parts to a 123 block for the second op

For op 2, I clamped the 123 block in my little self-centering vise, so I could access all sides. After finishing op 2: And a pile of chips after machining 3 of them in a row:

This was my first time machining steel on this router, and it did admirably. Finishes turned out excellent:

A pair with hardware installed. I could populate any of the insert locations, depending on if I’m holding small parts or need more holding force:

And here’s an example of using one pair to clamp a 340x220x19mm aluminum plate: