N3ZN Single-Lever Key Fingerpieces

An email was sent to Tony, N3ZN, enquiring if there were alternative fingerpieces to the stock ones that came with the key. I was informed there was no alternative to the stock fingerpieces available. Within several minutes of receiving that email response, a quick online search resulted in one person making fingerpieces for the N3ZN keys. I thought they were quite pricey coupled with thinking that a set could be made for what was really desired – keeping my wrist at a natural position when operating.

Several small 12x12-inch sheets of black plexiglass were ordered. There was some preparation work to be done though while waiting for the plexiglass to arrive.

The ZN-SL’s fingerpieces were removed with one being scanned-in. In Visio^[1], that fingerpiece image was inserted and sized to 100% of their overall measured size, 26.25 x 38.5 mm^[2]. That “template” was then used as the basis for a new fingerpiece outline. The focus was getting the soon-to-be fabricated fingerpieces to extend down towards the operating surface. I elected to get the fingerpieces’ “ear” down to about even with the bottom of the key’s base. The overall size was targeted to be about 43 x 38 mm.

A 45 mm wide strip along the edge of the recently arrived 12 x 12-inch black plexiglass was cut on the band saw with a new 24-TPI blade. That strip was then cut into ~40 mm blocks. That gave me 6 blocks. The blocks were stacked on top of each other using several strips of 2-sided scrapbook tape between each block’s protective surface paper with each block’s uncut and true straight edge being aligned and flat. That flat edge was now the reference for measurements and forming. A cutout of the new shape’s outline drawing was taped to the top block using the 2-sided scrapbook tape

The new fingerpieces rough shape was cutout from the block using the band saw. Between using a combination disc and belt sander for the outside curves, and a small ~1-inch round sanding “tube” inserted in the small drill press for the tight inside curve, the overall shape of the new fingerpieces were made. The two (2) mounting holes were measured, marked, and drilled.

The only regret is failing to get pictures of the cutout and forming of the 6-stack “fingerpiece block” (with it still being winter and the small space heater on, I was only out in the garage for maybe an hour or so each time due to getting cold).

^[1] Even though a docked MacBook Pro 15-inch (2019) is used exclusively, Microsoft’s Windows 10 runs within the Parallels application. That allows me to run a few ‘Windows only” ham radio and other applications such as Visio.

^[2] I find it much easier to work with metric, and especially with small items. Note: I used to live and work overseas for about half of my career. Personally, I really wish the US would “go metric” as it is just so much easier to work with.

The block was separated into three (3) pairs of fingerpieces. Each pair was marked on that flat uncut straight edge with either one, two, or three “scratches” with the backside of an Exacto blade – I wanted to make sure each pair was marked in case being separated later.

Each pair was filed and sanded for a left and right fingerpiece. The filing was done to get the each one’s edge “close”. Then, there was a lot of sanding with finer grit starting with about 120 grit down to 800 grit sandpaper strips getting each fingerpiece’s left and right outside rounded and smooth. The inside edges were just “touched” enough with some sandpaper to get the sharp edge off each piece. The filing and especially the sanding took the longest to get done for the 3 pairs. The plexiglass’s protective paper was left on until the very end. The drill press vise’s jaws were covered with masking tape as an added precaution against scratches.

The edges were then finished and polished with a Dremel tool set on the slowest speed using a small axial felt pad. Each fingerpiece pair was polished using some auto compound polish that I had (and about dried-up since not having used it in a long time). That seemed to really worked good in getting the edges polished.

The mounting holes needed to be “touched up” a bit relative to each fingerpiece’s clean or straight edge – there was too much distance between the edge and the first of the two mounting holes. Using the double-sided scrapbook tape once again, the fingerpieces were again formed into a block aligning the previously drilled holes and the straight edge. With some 800-grit sandpaper on the 6-inch disc sander, the block was “trued-up” sanding down a little bit at a time until getting the right distance between the straight edge and the first mounting hole.