Mini PTFE Tube Grommet

**Pictured prints don't match the STLs due to stylistic updates. No dimensional or functional changes have been made.

*ed 20191224 #2: Because I evidently can't type numbers today to save myself (I blame the heat) I've had to re-upload the hex bulkhead as I'd sized it for a 4.5mm hex instead of 5mm (which I'd originally mis-typed as 6mm). I've also uploaded a new version of the standard bulkhead, and both now have the provisions for a 5mm hex or a blade screwdriver to assist with installation.

*ed 20191224: Added a hex-head variant. All parts are interchangeable between the two - it's simply a different way to get a grip for tightening. Hex-head variants can use a 14mm (~9/16") spanner externally, while a 5mm (~5/16") allen key can be used for the bulkhead. NB These parts are not designed to be load bearing.

While looking for a suitable grommet to use for a filament dry box, all I managed to find were what I consider to be excessively large options which require a hole of 16mm or larger to be used. Since the tube I'm running is only 4mm across, I figured I could do better.

The resulting Mini Grommet fits a 9mm (approximately 3/8") hole, is 12mm deep and 14mm across. The through collar is 7mm tall and 14mm across, while the blind collar is 14mm across at the widest and 52mm tall, offering approximately 50mm of total interior depth. EThe washer is 15mm across and 0.6mm thick.

A single through grommet consisting one one bulkhead, two washers and the through collar takes approximately 20±5 minutes (plus heating) with standard cartesian settings. Printing a full set of two bulkheads, four washers, and one of each collar, takes approximately 55±10 minutes (plus heating).

Due to the small contact area a brim or raft may be required for some printers (I didn't use one), and supports are unnecessary.

I would highly recommend using a printer with well tuned linear advance (or equivalent) or coasting, as all fit tolerances are between 0.1mm and 0.2mm. Any surface blobs or inconsistencies may need to be dealt with by hand if they cannot be avoided during the print.

Also be wary of elephant's foot. Too much first layer squish may make the opening smaller than the required 4mm, in spite of the provided chamfer. A small hobby knife or countersink bit can be used to clear away the excess.