3D printed hose adapters: stop buying, start measuring

10 October 2026

hosebasics

Every workshop has a box of vacuum adapters that almost fit. The shop vac hose says 2-1/2 inch, the sander port says 35 mm, and the plastic reducer from the hardware store wobbles on one of them and needs tape on the other. A 3D printed hose adapter fixes that for a few grams of PETG, as long as you type the right numbers.

The label is not the size you need

Hose sizes are named after the bore. A 2-1/2 inch shop-vac hose has a 2-1/2 inch hole through it, but its male tool end measures 57.2 mm on the outside (Rockler lists 57.15). Type 63.5 mm because that is what 2-1/2 inches comes to, and the adapter falls off.

Dust collection fittings are worse. A 4 inch male stub runs anywhere from 100.7 to 101.6 mm depending on who made it, and a 2-1/2 inch dust collection stub is 62.2 to 63.5 mm, nowhere near the shop-vac hose with the same name.

Use calipers and ignore the label.

Into or over: which surface to measure

The hose adapter generator asks one question per end: does this end slide into the other part, or over it?

• Into a hose or a socket: measure the inside diameter of the hose or port. The adapter's outside gets that number.
• Over a stub or a hose cuff: measure the outside diameter. The adapter's inside gets that number.

Some ends are conical (the Festool D27 tool end is one), so measure where the adapter will actually sit, not at the very mouth.

The rest of the adapter is a tube between those two numbers, with a 2.4 mm wall by default and a cone of about 30 degrees from the axis between the ends, so it prints standing up without supports.

Why 0.4 mm of taper

A straight tube of exactly the measured size either won't start or slides on with no grip at all. So each end gets a taper over its engagement length. An end that slides into something is 0.4 mm slimmer per side at the tip and reaches full size where it stops, which means it jams tighter the further you push. An end that slides over something gets the same 0.4 mm as a flared mouth: it starts easily and closes on the port.

On top of that sit 3 grip ribs per end, 0.35 mm high. For a soft hose you can switch them to barbs, a long ramp going on and a 45 degree back face that bites when you pull. Barbs that go into a hose stand 0.5 mm. On the outside of a rigid port they stay at 0.35 mm, because hard plastic does not give.

If the port slides in too deep, turn on the stop. On an into end that is a 2.5 mm collar for the hose to butt against, on an over end a 1.5 mm inner lip the port bottoms out on. Both have a 45 degree face and still print without supports.

The taper that turned the wall inside out

I found a hole in the taper in September. The page allowed a 2 mm taper and a 1.6 mm wall, each fine on its own. Put both on an into end and the tip's outer radius came out at 18 mm while the bore was 18.4 mm. The inside of the tube was bigger than the outside, the mesh crossed through itself, and a slicer would have had to guess what I meant.

The generator now refuses any taper that leaves less than 0.4 mm of wall at the tip. The message names both numbers, so you can decide whether to thin the taper or thicken the wall.

Ports with known sizes

For common tools I put the numbers into a list on the page, each one with its source. Picking a tool fills in the diameter and the fit:

• Shop-Vac 2-1/2 in hose, male end: 57.2 mm, the adapter goes over it
• DeWalt DWE7491 table saw: 63.8 mm outside (two separate measurements gave 63.5 to 64.0)
• Makita BO5041 / BO5030 sander: 24 mm stub
• Ryobi 10 in compound miter saw: 38 mm outside
• Bosch VH1635 35 mm hose, tool end: 35 mm bore
• Metabo: 35 mm socket or 28 mm stub
• Dust Deputy 1-7/8 in port: 50.8 mm outside

A few entries rest on one measurement by someone other than the maker, like the Festool D27 tool end at 35 mm. Those are marked approximate, and the page asks you to check with calipers. Tools with no published figure at all, such as the DeWalt DWS520 track saw or the Makita LS1019 miter saw, are not on the list. I would rather leave a field empty than fill it with a guess.

Printing it

Stand it on end A. Straight adapters need no supports and no infill, since the whole part is wall; give it 3 or more perimeters. PETG grips and flexes better than PLA on a warm workshop hose. Elbows past 30 degrees overhang, so use tree supports that touch only the outside, or print them lying on the bend.

If your sizes are common, there is a ready 57 mm to 35 mm adapter for a shop-vac hose on a sander, a 100 mm to 63 mm reducer for a chip extractor and a 57 mm 90 degree elbow. The hose adapter library has more, from 30 to 100 mm.