Pantograph

Handy especially for engraving - maker's marks etc.

Can zero the gauges on the hand wheels by loosening the large knurled nut and hand placing the gauge at 0", before tightening it again

There are axis locks but you typically won't need to use them when engraving - X lock is underside of the machine below the knee, Knee lock is to the left of the knee wheel, Y is on the left side of the worktable.

Machine has two tables: Pattern table (which holds the pattern) and work table (which holds the piece being engraved).

All adjustments use 3/4" wrench, or the two small collet wrenches for changing end mill bits.

Letters and operator's manual in the right side desk drawer

3/8" collet is holding a reducer collet 

2D Mode

1. Decide on the reduction ratio - how small the result is. All three segments of the arm should be set to the same value indicated on the top of the segment. All 5's for 5:1, all 3's for 3:1 etc.
2. Styluses are 1/8" delrin.
3. Ensure it's at the highest speed if engraving (20k RPM); for larger bits consult the table on the plaque on the side of the machine

3D Mode

Discouraged for the time being - need some special alignment between the main Z pivot, the milling spindle end, and the stylus, which is easy to get wrong. Also requires the stylus to be the same ratio larger than the end mill (e.g. 5x larger for 5:1) and to match the topology (ball for ball nose etc.) which is also confusing and weird.

Size increases

Could swap the spindle and the stylus to do larger things, but it adds error and isn't the strong point of the machine. Requires moving the spindle and the whole tension bar etc. Never been attempted.