HNDL | the Ream Team - a Tool for 3D Printing.

Since the very early days of 3D Printing, round and correctly sized holes have been a bit of a myth. A solution, and one I have been a strong practitioner of, is to use a reamer. Of late, this has primarily been a drill held in a spare chuck.

After building a workshop in the first half of this year, the space has been calling out for some new tools, the mismatched jumble of chucks needed replacing with something a little more refined.

HNDL is not the first set of Reamers I have designed, my original version released back in November 2016 on Thingiverse. A few months later a fling with OpenSCAD birthed a customisable version, a printed example of which is in the images above. It is now 2025, technologies have changed, and printers have evolved, but holes still need reaming.

You'll need,

1. 1 x 3D Printer.
2. 1 x 2.5mm Hex Driver.
3. 1 x M3 8mm Bolt Per HNDL.
4. 1 x Roll of Dry Filament, I used PETG-CF.
5. 1 x Box of Drills.
6. 1 x Set of HNDL handles (see Step 3).

While out looking for drills to serve as reamers, I came upon a pair of Bosch Impact Control bits. Interestingly, they have standard 6.35mm , 1/4" Hex Drive. This got me thinking.

One of the issues, the main issue, I had with the old versions, was that the drill bits would spin in the handle when the boring got exciting. One would normally solve this by grinding a flat on the drill bit, but it's not a very good solution, especially if you don't have a grinder. The hex bits seem to provide a real solution to this, due to their non-circular geometry, they can't rotate. What we now need, is a handle with a hex hole.

The HNDL handle is as an exact match for the 1/4" Hex Drive as I can manage, times three. It's an obvious answer to the complicated question of aesthetics. I can skip all the clever stuff usually done by industrial designers by simply inflating the hex and turning that into a handle for HNDL. Genius.

Behold, a hole. The eagle-eyed amongst you will no doubt have spotted the interesting central geometry. To get away from the complicated nature of printing holes, namely the under sizing, I have added 1mm 'lobes' on each of the six corners. This will prevent any problems when it comes time to install the bits.

An added bonus, and a neat little trick, is we can use the lobes to vertically align the seam into when slicing. This keeps the seam line away from the hex, and the contact faces clean.

To stop the drill from pulling out, a single M3 8mm bolt fixes the drill in place. I did think about making a latching style lock, but decided against it for several reasons; Firstly, I don't really need to take the drills out once they have been installed, and secondly, it would wear and likely not be strong enough in worst case scenarios. The bolt is easy enough to remove.

The HNDL handle files are multi-material. The numbering for the drill size is nested into the end of the HNDLs. They will of course still print if you have a single material machine. Simply ignore and don't print the separate numbers.

There are two storage options; an 8 HNDL Stand, or a 3 HNDL Case.

I am using a Bambu Lab A1 Mini and the AMS Lite. I have a set of DryAF 100% Metal Spools installed onto the AMS Lite.

The HNDL files can be downloaded from here | HNDL

This is the easy part. Simply slot a drill into a HNDL handle, 1/4 Hex Drive first, and then screw in an M3 8mm bolt to secure it. Simples. If you do run into any issues at this stage, please post a comment, I'd love to know what is going wrong.

It is perhaps at this point that one should give the olde 'Contents is hot' warning and point out that drills are sharp, at least good ones should be, and that you shouldn't lick them. It hurts, trust me.

In addition to the case, and stand, I have also modelled up a wall mounted rack. You'll no doubt have seen the HNDL-RACK-X STLs etc in the files download, simple pick the one you want, print, mount and hang HNDLs.

Each Rack has two fixture points for M3 sized screws or bolts.

Obviously, you can use any other tool or equipment that uses the 1/4" Hex Drive standard in a HNDL handle.

Prizes go to the peoples who have the most obscure things with a 1/4" Hex Drive.