Note: this design has been updated to mini-reel version 3.

The mini-reel is a reel for SMD components on cut tape. It is compatible with the standard 7" reels, only smaller. Its capacity is therefore also much smaller: about 1/4th of what a 7" reel can hold.

Design

Most importantly, the design follows the standard for reels for the essential dimensions (EIA-481). The mini-reels that were once on the market had a diameter of 100mm, and this design inherits that size.

That said, the mini-reel is designed in OpenSCAD and all dimensions can be configured (with the OpenSCAD "Customizer"). You could even use this design file to generate standard 7" reels.

The suggested (and preset) dimensions of the mini-reel are: outer diameter = 100mm (nearly 4"), hub diameter = 50mm, spindle (arbor) diameter = 13mm. There are presets for tape widths of 8mm, 12mm and 16mm, and the inside width of the reel is always 1mm wider. The "wall thickness" of the flanges is 1mm, meaning that the total thickness of a mini-reel is the tape width plus 3mm.

The mini-reel is printed in two parts, which are then glued together. One side is almost closed; this is the side on which you would put a label with the part information. The other side has three holes, to make it easier to stick the tail of the cut tape into one of the three slots. These three slots have varying widths, and this is because cut tape has varying thicknesses. The narrowest slot that the tape still fits in, typically holds the tape best.

Rationale

At the turn of the century, when SMD components were not as ubiquitous as they are today, you could get parts in a quantity of 1000 on a mini-reel. It made sense, especially for prototyping and the smaller manufacturing services: you could often not re-use left-over parts of one project in another, because SMD parts were still special. So for a small series, you would rather buy mini-reels instead of standard 7" reels (that hold 4000 or 5000 parts).

This changed as SMD parts became more and more common. Sales of 7" reels increased and those of mini-reels decreased, up to the point that part manufacturers decided that mini-reels were no longer commercially viable. Mini-reels all but disappeared from the market.

While mini-reels may not be commercially viable, there is still a use-case for them. The fact that several distributors offer a "re-reeling service" proves that there is still a market for buying smaller quanties, but still receive the parts on a reel.

When it comes to storage, small reels take less space than large ones. That, in a nutshell, is my rationale for the mini-reel. For a small company, with a small stockroom, but still a large selection of different components, all those barely filled 7" reels are a waste of space.

Alternatives

When starting my design, I was aware of a similar mini-reel design on Thingiverse. After the fact, I also stumbled upon another, even smaller desing, also on Thingiverse. Neither design appears to be parameterizable; they are both for 8mm "paper-tape" style cut tape. Since I wanted a configurable design, for at least 8mm and 12mm tape, plus that we needed a mini-reel that is also suitable for embossed carrier tape (thicker than paper carrier tape), I continued with our own design regardless.

Print instructions

I recommend that the parts are printed on a smooth surface (so not on a "textured" steel sheet). You will want the top side of the reel to be smooth for the label to stick well.