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The Single-Blow Can Opener: A Ring of Pointed Teeth Punches the Hole

Thomas A. McFarland, Meadville, Pennsylvania · Public domain (expired patent)

أنشأه

Forge

6. أكتوبر 2026

The Single-Blow Can Opener: A Ring of Pointed Teeth Punches the Hole

Cutting into a can with a single blade takes several cuts or blows. Thomas A. McFarland of Meadville, Pennsylvania, received US 64,891, dated 21 May 1867, for "a cheap, simple, and effective implement for cutting an opening in a can by a single blow": a ring of curved pointed teeth on a handle's head, bevelled inside, whose points enter first and whose edges widen until they meet, punching out a plug that stays inside the cutter. This rung works out why pointed teeth need so little force, then files the teeth on a steel tube and punches a can top with one blow.

متوسط

About 3 hours

التعليمات

Peak force and work

جارٍ تحميل دفتر Jupyter…

A single blade before it

The embedded blueprint cuts a can top a slit at a time with one blade. McFarland rings the blade round into teeth so one blow cuts the whole opening.

Read US 64,891

"In operation the tool is placed on the head of the can, and the points of the teeth driven in by a smart blow, and the cutters forced down until their forks or bases have cut through the can, when a piece will have been cut out of the form of the cutters." "The teeth being bevelled on the inside tend to compress the plug removed, and cause it to remain inside the cutter, thus facilitating its removal from the can."

Cut and mark the tube

Cut 40 mm of 25 mm steel tube. Mark six teeth round one end, 12 mm tall, their bases touching.

المواد لهذه الخطوة:

أنابيب فولاذية إنشائية1 قطعة

الأدوات المطلوبة:

منشار حديد

ملزمة منضدة

قلم تعليم ثابت

مسطرة

File the teeth

Saw a V between each pair of marks and file the teeth to points. Bevel each tooth's inside edge with a round needle file; leave the outside flush.

الأدوات المطلوبة:

منشار حديد

مبارد (مبرد يدوي)

طقم مبارد إبرية

ملزمة منضدة

نظارة أمان شفافة

Fit the handle

Sand a hardwood dowel to fit the tube's other end, glue 20 mm of it in with epoxy, and leave 100 mm as the handle.

المواد لهذه الخطوة:

أوتاد من خشب صلب1 قطعة

إيبوكسي ثنائي المكوّن1 قطعة

الأدوات المطلوبة:

ورق صنفرة

قدمة رقمية 6 بوصات

The build in 3D

FreeCAD model of this build, not of the patent: a 25 mm steel tube with six 12 mm pointed teeth bevelled inside, on a hardwood handle.

ملف التصميمBLENDCC0 - Free

تنزيل النموذج

Punch a can top

Stand a sealed can on a hardwood block. Set the teeth on its top and strike the handle once with the mallet; count the blows needed, and measure the plug with the caliper.

المواد لهذه الخطوة:

علبة صفيح1 قطعة

كتلة خشب صلب1 قطعة

الأدوات المطلوبة:

مطرقة مطاطية

قدمة رقمية 6 بوصات

قفّازات عمل جلدية

نظارة أمان شفافة

Teeth that bend, skid or leave the plug

Single-blow can opener troubleshooting.

Flow

History and honest limits

**Thomas A. McFarland** of Meadville, Pennsylvania, received US 64,891, dated 21 May 1867, for opening oyster, fruit and other cans. The cutters are curved to fit a shoulder on the handle's head and fastened by screws; they may be one piece or sections. He disclaimed cutting an opening broadly, single shear-like cutters, and cork borers with spring handles, and claimed the handle and cutters cutting a plug at a single blow. **Honest limits.** Mild steel tube is not hardened; the notebook's shear figures are estimates. Your blow counts are the result.