About this project
A three-member telescoping drawer slide, printed as three separate rails that assemble by sliding together. Full extension: the inner rail runs out by the whole member length in two stages.
How the section works
Each member wraps the one inside it with two arms that hook over at 45 degrees, so the stack is captive without any ball bearings or retainers. Lip depth is how far each arm hooks in, and it is the number that decides whether the stack can be pulled apart sideways.
Every gap in the section comes from Running clearance. The 45-degree bearing faces get their own multiplier, Slope factor, because a flat gap measured perpendicular to a sloped face is not the same gap — the Fit readout reports both.
Dial it in first
Turn on Coupon mode and print the short stubs. That is the whole point of it: it shrinks every member and lets you test a running clearance in ten minutes instead of two hours. Start at 0.15 mm and go up in 0.05 mm steps until it runs freely without rattling.
Stops
Each stage has a lug that runs into the end of the lip relief in the member outside it, giving exactly half the member length of travel per stage. The lugs have a 45-degree lead-in on the back so they snap past the lip during assembly and then cannot come back out.
Preview
Extension runs the slide out in the viewport without changing any geometry. At 1 both stages are hard against their back stops, and the Extension readout says how much overlap is still engaged there.
Mounting
There are no mounting holes and no detent — the rails come out plain. Drill the inner rail's mounting plate and the outer web to suit whatever you are fixing them to; Inner rail plate thickness is the material you have to work with.
Printing
All three members flat on their backs, no supports. The 45-degree faces are self-supporting by design. Print in PETG; PLA creeps under a loaded drawer. Three perimeters minimum — the lips are load-bearing.