Cheek parts were cut from 5mm thick mild steel. At first hols to accept centre pins were cut. The textbook specified 2.5mm, but I did not have 2.5mm shaft on hand. So I changed it to 3mm.

耳の部分は5mm厚に調整した軟鋼から作ります。まずはピンの入る穴を開けます。教科書では2.5mmになってますが手持ちにそんなサイズの線材がないので3mmに変更。

The grooves were entirely cut by slotting saw in many strokes. This method is much less stressful comparing using end mills.

溝はエンドミルを痛めたくないのですり割りフライスで何回かに分けて切りました。

Finished groove. The arrowed part was to be interlocked to expansion link body.

溝切り完了。矢印の部分は本体の溝とかみ合う部分です。

Ends were rounded.

耳を丸めます。

The link body and the cheek pies were silver soldered. A piece of 3mm SUS303 rod was inserted through cheek piece and link body. The arrowed parts were spacers to keep the relationship of link body and cheek piece made from 5mm brass rod. The interlocking parts were applied with silver solder past. However I found when the past applied the location pin can not inserted. The solder past seemed require some gap, say about 0.2mm. I had to file down the interlocking grooves. Some solder past was also applied outside of the interlocking part.

Actually I tried normal silver soldering before using silver solder past. However it was too hard for this sort of small and tight places.

次にリンク本体と耳を銀ローづけします。矢印のスペーサーを5mm真鍮棒で作って、3mmのSUS棒で本体と耳を仮に固定。この時、勘合部分には練り銀ローを塗っておきます。練り銀ローを塗るとピンが入らないことが判明。練り銀ローをおさめるためのギャップが0.2mm位は必要なようです。やすりで反対の勘合部分を削りました。さらに練り銀ローを接続部分に盛り上げておきます。実は一般の銀ローでも試したんですが見事失敗。こんな狭い部分のローづけは私の手には負えません。練り銀ローは必需品です。

Silver soldering. Heating was very easy with silver solder past. Just heat up until the past melts and flows.

銀ローづけ。練り銀ローは適当に加熱するだけでついてしまうのでとても楽です。

Parts were soldered quite nicely.

結構しっかりついています。

The centre pin was bonded by Loctite. I thought to silver solder the pin at first, but it would be too hard.

ピンをロックタイトで接着。はじめは銀ローづけをしようと考えていましたが難しすぎですね。

I waited a day for curing of Loctite and cut out he centre part of the pins.

一日待ってから、ピンの真ん中をすり割りフライスで切り取ります。

Cut out the link from the cheek piece.

耳の後ろで切り離し。

Finished expansion link. This would be the most difficult parts ever built in this project to this stage.

完成しました。これは今までの部品の中で一番むずかしかったかもしれせん。

Installed to the motion plates. They moved smoothly.

モーションプレートに組み込んでみます。軽く動きました。