Fit-test and print guide

What the coupon is

The fit-test coupon is a thin slice of the mounting edge of the design you are exporting. It keeps the two ears and their real mounting slots, joined by a spine, so it spans the panel's full 254 mm width while using a fraction of the filament: 3 mm thick, and about 14 mm tall on the shipped profiles. The slots in it are the slots in your part — same height, same play, same spacing — and it is cut from the design you are exporting, so it tests that design's mounting rows rather than a generic sample.

Why it exists

Two things vary from one build to the next: the rack, and the printer. Racks in the 10-inch class have no single published standard behind them, so the numbers a profile ships with — a 254 mm panel, 236.525 mm mounting-hole spacing, hole centres at 6.35, 22.225 and 38.1 mm from the bottom of each U — are a measured starting point, not a promise about your rack. Your printer adds variation of its own: a first layer that squashes wider than the drawing, a slot that comes out a few tenths tight, filament that shrinks as it cools. None of that is a flaw in the design, and none of it is settled by printing the finished part and finding out. The coupon splits the question in two: does the part match the rack, and does the printer make the dimensions the design asked for.

Printing it

Print the coupon the way you intend to print the part — same printer, same material, same layer height — or you are testing a different process. PETG is what these racks are designed around. There is nothing to support and nothing to orient: the coupon is a flat plate 3 mm thick, and the STL is already lying flat on the plate. If it needs a brim to stay stuck, the finished part will too, and that is worth finding out now. Expect a few grams of filament and a few minutes of printing.

What to look for

• Line-up.Start one screw at each end. Both slots should sit over the holes you intend to use without force. The rack's holes are at 6.35, 22.225 and 38.1 mm from the bottom of each U, and the coupon is cut at the mounting row your design uses.
• Travel.Slide the coupon left and right through the slot play — 2.5 mm each way on 10RackMaker v2, 2 mm on the 10-inch standard. If one end runs out of travel before the other lines up, your rack's holes are further apart or closer together than the profile says.
• Screws. Each screw should pass through its slot without binding and clamp the ear flat against the rail. Binding usually means the slot is too small for the screw; a panel that still shifts under a tightened screw means the slot is too large.
• Flatness. If the coupon rocks or stands off the rail, that is the rack rather than the part — rails that are not square, or a mounting face that is bent, do it. The finished panel will sit the same way.
• Room around it.Check that the coupon's outer edges clear whatever sits beside the rails: a side panel, a cable arm, the frame itself. The finished panel is the same 254 mm wide.

If it does not fit

Change one number at a time and print another coupon. Change two at once and you will not know which one fixed it. Every number below is editable in step 1 of the designer, and the part is rebuilt from whatever you enter.

Mounting-hole spacing

The distance between the left and right holes: 236.525 mm on both shipped profiles. If the coupon's slots will not line up with the rack, measure that distance on your own rack and enter what you measure. This is the first number to change and, on most racks, the only one.

Slot height

The clearance the screw shank passes through: 5.6 mm on 10RackMaker v2, 6.6 mm on the 10-inch standard. Increase it if screws bind on the way in; decrease it if a tightened panel still shifts.

Slot play

Extra travel cut each side of the slot so the panel can shuffle left and right before it is tightened: 2.5 mm on v2, 2 mm on the standard. Increase it if the slots cannot reach the rack's holes at all.

Shelf width

The shelf behind the plate: 218 mm on v2 against 222 mm of measured clear width; 210 mm on the standard against 220 mm. If a shelf fouls the frame before it is home, reduce it.

Rear-rail depth

How far behind the front plate the rear rails sit: 250 mm on v2, 180 mm on the standard. If a shelf's rear ears do not reach the rear rails, this is the number that is wrong.

Panel width

254 mm on both profiles. Leave it alone unless your rack is not a 10-inch rack.

Where to go next

• Rack profiles — every number a profile carries, what it means, and when to change it.
• How it works — the six steps, with the coupon in its place in the workflow.