CADDManager on March 3rd, 2016

I collect old books.  Not rare books or expensive books, just old, used books. I love the smell of a used book shop. I love finding unique items that I think are interesting (others may find them dull). I have a lot of old bibles, dictionaries and encyclopedias. I tend to like technical/reference books. I have and extensive collection. Nothing overly impressive. Just things I like.  I select them based on many factors. The binding, cover, graphics inside, content, topic, outdated perspectives and more.Mechanical_Eng

Since it is Throw Back Thursday, I decided to post on this topic with a quick reference from one of my finds.

The Hardness of Lead in your Pencils. For artists, this is still a current topic. For drafters, not so much. But if you are ever in need of knowing which lead is harder or softer… here you go.

I purchased the seventh edition of the Standard Handbook for Mechanical Engineers (c) 1967. It has a wealth of great info, like (nerd warning) Heat Transfer calculations, Fluid and Solid Mechanics, Surfaces and volumes,  Copper wire resistance, Vibration effects, Geometry and Trigonometry.

This was inside the cover of a book I bought. Written by a prior owner of the book.

Lead_List

Here is a chart of the same info – from draftingmanuals.tpub.com

Pencil_lead_hardness

 

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