flexible couplings for PCB router

Hi to the list,

I'm designing and building a small PCB router, gantry style. Size is about
12" W x 12" L x 12" D. I'll be using stepper motors; this project was to be
"from stock on hand". I salvaged a couple linear slides.

I also found linear bushings and precision shafts on E-bay that look to do
the job, I thought I might as well find commercial parts as well. The lead
screws are another subject!

I'm familiar with helical beam couplings (my CNC'd Sherline has them).
Anyone ever use slotted disk couplings, also known as Oldham couplings?

McMaster Carr under couplings:

Hub 3/4" D. 7/8" L. 3/16" to 1/4" shafts. 59985K2 $8.02, 2 ea.
+ disk 59985K62 $1.46 or 59985K92 $2.29

Helical couplings:
3/4" x 3/4"; 3/16" to 1/4" 6208K4 $20.50

Not cheap!

McMaster says neither have backlash. The Oldham couplers would make it much
easier to assemble/disassemble. Seem to tolerate similar miss-alignment.

Looks like I'll be mounting the NEMA #23 steppers on short threaded rod. I
really like the Sherline mounts, but other then using a piece of pipe for
the standoff and LONG bolts, I don't have a similar design in mind.

Alan KM6VV