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Category: Tutorial (Page 1 of 3)

Jinhao Fountain Pens

Jinhao is a Chinese maker of inexpensive fountain pens. I have dozens of them. They are of remarkably high quality given the price. They are beautiful pens that often work well right out of the box. If not, a full disassembly, deep cleaning, and careful reassembly will usually fix them. Unlike most nibs, Jinhao nibs rarely need adjustment or polishing to work well and write smoothly. My experience is that they’re fine right out of the box. I don’t see how Jinhao achieves such high all-around quality this for such a low price but they do.

Along the way, I’ve made some notes for myself on nib and feed sizes and which Jinhao pen models fit what.

Jinhao makes some pens for #5 nibs, some for the considerably larger #6 nib, and a few for #8 nibs. (For reference, a TWSBI Eco takes a #5 nib.) While nibs are interchangeable between brands, feeds are not. Jinhao makes three kinds of feeds, a 5mm feed for #5 nibbed pens, a 6mm feed for #6 nibbed pens, and a feed for pens with #8 nibs. Jinhao feeds are exceptionally long compared to other brands, which I see as a good thing because it holds more ink. A long feed like that means its less likely to experience ink starvation when using broad nibs of flex nibs that need high ink flow.

If you’re a do-it-yourself pen jockey, I only have one warning or recommendation. It’s important in every fountain pen for the nib’s breather hole to be properly positioned on the feed. Some pens like the TWSBI Eco have helpful alignment guides molded into the feed. Just place the nib exactly where it fits on the feed and shove it into the section. Can’t miss. Not so with Jinhaos. Jinhao pens have an alignment feature so the feed fits properly into the section but no help with nib alignment is provided. Nib alignment can be challenging. I use magnification, bright light, and patience to get it right. And you must get it exactly right or the pen will misbehave. Once you get it, it’s rock solid but be prepared for a challenge fiddling with it.

The vast majority of Jinhao pens come equipped with M (medium) nibs. If you want a different line width you’ll have to change the nib yourself or get a pen jockey to do it for you. Jinhao makes nibs in several widths but they must be bought and installed separately.

Below is a list of Jinhao pen models with #5 nibs:

82, 163, 165, 188, 250, 301, 500, 599, 601, 950, 991, 992, 5000, 5099, 8802, 9009

Note that some model 82 and 992 pens seem to need a slightly larger nib, like a 5-1/2. A #5-1/2 or #5 will fit. If the fit seems a little off, some slight tweaks to the base (heel) of the nib will fix the problem.

Below is a list of Jinhao pen models with #6 nibs:

100, 159, 316, 450, X450, 750, X750, T1, C1

Below is a list of Jinhao pen models with #8 nibs:

X159, 9019

Please comment with any additional Jinhao model information, tips, or corrections. Thank you.

Lithium Battery Hazard

Lithium batteries are more dangerous and more delicate than I or my friends thought. It’s good to be aware of the dangers and treat them properly to minimize the danger.

For years now we’ve seen occasional reports of electric vehicles, cellphones, and notebook computers catching fire and sometimes burning spectacularly. It’s not common but it happens. One might say, “Oh, but that’s EV’s. That’s a special case.” It’s not. For the first several years, Tesla’s EV batteries were built out of 18650 lithium cells, 4,000 of them. These are the same cells found in power tool battery packs from Black & Decker, Porter Cable, DeWalt, and the rest. These are the same cells found in some notebook computers, flashlights, and many vaping devices.

There are several lithium battery chemistries. What I’m talking about here is the most common: NMC or Nickel Manganese Cobalt Oxide.

One of my 18650 Lithium NMC Cells

18650 refers to the physical size of the cell, 18 mm in diameter by 65 mm long. Other sizes exist but the 18650 is the most common shape.

An Incident Occurs

Like everyone else, I’ve been using lots of these batteries without issues. What caught my attention was an incident that happened a couple of weeks ago to a friend and co-worker. He got up in the morning to make coffee and noticed an odd smell. It smelled like overheated plastic, or failing electronics, or a pot left to burn dry on the stove. He walked back and forth in the house and determined the smell must be coming from his bedroom. Nothing was immediately apparent so he searched and found the cause. Under the bed was a plastic tote where he kept the batteries for his cordless garden tools. Since it’s been winter, those batteries had been there untouched for almost six months. Now, one of them was warm and plastic housing showed evidence of melted plastic and a hole where the plastic had boiled. He took the tote outdoors and called me. I went and took a look, took some photos, and noted the strong smell. Despite opening windows and ventilating the house, the smell lingered in the house for several days.

Later, he mentioned that the way the battery attaches to the tool is awkward and that he had dropped that battery on concrete from a height of about 1 meter. This cracked the plastic case. He thought nothing of it, glued the case together, and the battery continued to work normally. This news sent me digging on the Internet for information. I found quite a lot and learned some important things I didn’t know.

Dry Cells (Alkalines) Compared to Lithiums

Cylindrical lithium batteries like the 18650 are much more delicate than dry cell batteries. Dry cell batteries like alkalines are filled with a few simple bulky materials. Close manufacturing tolerances are not required and they are physically robust. Dry cell batteries can be dropped, dented, and partially crushed and won’t short-circuit. They usually continue to work. Even if a short somehow occurs, they fail gracefully. The maximum power they can deliver is limited and will not result in pyrotechnic jets of white hot flame or violent explosion.

Below is a table comparing old style dry cells introduced in 1898 , alkaline dry cells, and modern NMC lithiums. It shows the total energy content in MJ/kg (megajoules per kilogram), the total energy you can expect to get out of a cell in Wh/kg (watt-hours per kilogram), and the “specific power” the cell can deliver in W/kg (watts per kilogram). More on specific power below.

LeClanche Dry Cell (1898)0.133610-27
Alkaline Dry Cell (1949)0.13-0.6885-19050
18650 NMC (2008)0.742053000-5100

From the above you can see that the differences aren’t that big except in one important way: watts per kilogram or specific power. Engineers use many terms like “specific power” that have agreed-upon meanings. In this case, specific power is the maximum amount of power a battery can produce for a short period of time. Short time meaning seconds or tens of seconds. Related terms would be instantaneous or pulse power (a fraction of a second) and continuous power (a long period of time or indefinitely).

As you can see, a lithium cell can deliver a hundred times as much specific power as an alkaline battery of the same weight. This jaw-dropping power to weight ratio is extreme, on the order of the engine in a top fuel dragster. Or, the engine in a Toyota Corolla producing 3,000 horsepower for a few seconds. It’s extreme. Over a period of a few seconds an 18650 can deliver enough power to heat itself smoking hot if it didn’t destroy itself in the process, which it would. This is the technology that enables the stunning performance of modern EVs.

At this point it should be obvious that short-circuiting an 18650 is a really bad idea. Just don’t. But what if an 18650 could somehow short-circuit itself? That would be really bad and is what we’ll talk about next.

Here’s the Problem

The construction of a lithium 18650 consists of paper-thin strips of film and foil rolled up like a jelly roll with a hundred paper-thin layers. Electronic engineers will recognize this type of construction from the way tubular paper, mylar, and electrolytic capacitors are made. This means that the positive and negative electrodes are very close together throughout the entire cell making it sensitive to dents, compression, bending, twisting, or any deformation from any direction. An unfortunate impact or dent can cause the cell to short-circuit, now or far in the future.

Diagram of a lithium cell. Note that in a real cell the anode and cathode are thin foil and the separator is also paper-thin.

Making things worse is the formation of so-called “dendrites” in lithium batteries. For years, dendrites have been a mysterious problem that’s plagued lithium batteries. It refers to an effect where repeated charge/discharge of a lithium battery causes the growth of microscopic hairs or threads of lithium. These can short or partially short a cell, resulting in reduced battery life and sometimes catastrophic failure. Recent research has answered most of the questions about dendrites. An understanding of them will hopefully lead to better designs.

This recent research discovered that microscopic fissures in the insulating layer of the cell result in pathways for dendrite formation. Cracks, fissures, or perforations as tiny as 20 nanometers are a problem. (For reference, human hair ranges from 50,000 to 120,000 nanometers in diameter. So we’re talking flaws that are 3,000 to 6,000 times smaller than the diameter of a human hair.) Impacts, dents, or other deformations can result in such fissures which encourage the growth of dendrites.

In other words, if you drop or strike a lithium battery you may have started the clock on a ticking time-bomb. That’s what happened to my friend. He dropped the battery, damaging one or more of the cells, and a year later, after six months of storage, unused, under his bed, the battery short-circuited. Research into impact damage of 18650 cells shows that dents of 3mm and even smaller are a problem. Impacts, especially end-on impacts might show no visible damage, yet the damage is done internally and a time-bomb might start ticking.

Nearly all studies done over the past ten years examined the immediate effects of damage with the main focus on EVs. What happens in an automobile accident? Only recently have studies been done on the delayed effects of impacts and indentations.

One additional fact I discovered is that dendrite growth accelerates rapidly at temperatures above 65C or 149F. This temperature is easily reached and exceeded on the dashboard of a car in the summer sun. Keep your lithium batteries cool and out of direct sunlight.


I hope this information is useful. After learning these things I purchased a steel .50 caliber ammunition box where I now store my lithium battery packs. My box is made of thick steel and I hope this is enough to contain a catastrophic battery failure. It’s certainly better than the canvas kit bag I used to keep my batteries in.

These insights are disturbing. More and more flashlights have lithium batteries. I have three flashlights specifically designed to use an 18650 cell. Many vaping gadgets are powered by 18650s. Any handheld device might be dropped on a hard surface without the user thinking twice about it. And if they are aware of the problem, what then? Discard the battery and replace it or try your luck?



The Lato Font

A few years ago I needed to print a manuscript of over 300 pages on my laser printer. The choice of which typeface, size, and weight have a big effect on toner consumption and legibility. Making the type smaller, lighter, or both saves toner (or ink) and paper, but one usually pays a price in poorer legibility.

This manuscript was for editing purposes and would be pored over for many hours so it had to be reasonably legible. The type had to be large enough to annotate with a pencil.

I wanted to have my cake and eat it too so I spent considerable time looking over a myriad of fonts. Since this wouldn’t be the last time this problem would arise, I felt the investment in time and effort was worth it. If a font really solved the problem, I was willing to pay for it. I didn’t limit my search to free fonts.

I searched several sites on the web offering thousands of free and pay-for fonts, concentrating on sans-serif fonts. I wasn’t looking for artistic beauty, I was looking for legibility. After finding nothing that stood out, I eventually tired of this and stopped. Then I tried different tack. An ordinary web search for “most legible font” led directly to what I wanted.

The Lato font family is fairly new. I had never heard of it. It was specifically designed for maximum legibility. The family is comprised of many variations, each carefully hand-tuned by the font’s creators, including a “light” variation and a “hairline” variation. Lato Hairline was exactly what I was looking for. It’s very light, composed of thin lines, but isn’t faint. It remains perfectly legible to my old eyes.

Since then, the whole family has become my standard san-serif / Helvetica style font that I use for everything instead of Liberation Sans, Arial, and Calibri that I used to use. You’re looking at it right now.

If you need a versatile, highly legible sans-serif font, you might give it a try. The Lato family is free to use for any purpose. You can find it at the link below or from Google, or Adobe.


Disclaimer: I have no relation to the above web site, Google, Adobe, or the creators of the Lato font.

Provisioning for Thanksgiving

Are you planning to host a Thanksgiving dinner? Do you know how much food to buy? Planning out a Thanksgiving dinner can be challenging. Since the Thanksgiving holiday is about plenty, you want to avoid running short. This can lead to making way too much food and eating leftovers for two weeks. Below are a few tips to help you.

I’m a retired engineer. I switched to the food preparation business ten years ago and can’t help but bring my engineering mindset with me. I study and learn every technique I can and study the chemistry of cooking. While I frequently cook things that I make up on the spot, for anything serious I like to have numbers and measurements. Below are some numbers you can use.

A Thanksgiving Spread

Turkey: 1 pound of bird (uncooked) per person, and you will have leftovers.

Dry mix stuffing like Stove-Top: 1 ounce dry mix per person

Potatoes for mashing: 6 oz (raw) per person or 3/4 of a large potato

Sweet potatoes: 6 oz (raw) per person

Canned cranberry sauce: 4 oz per person

Pie: 1 piece per person

Butternut squash: 7 oz (raw whole squash) per person

Brussels sprouts: 2.5 oz (raw) per person

Green beans: 4 oz (canned) per person

Extending the Above to 40 Persons

To extend the above numbers, multiply by the number of guests and round up to the next package size. Thanksgiving usually involves a lot of baking. If you try to prepare all the food on Thanksgiving day, you’ll need several ovens. Remember that cooking the turkeys will occupy your oven(s) for much of the day. Prepare as much as you can the day(s) before and reheat it.

Of course, you don’t have to do all of the items below. Just pick the items you think your guests will like. You don’t have to do squash and sweet potatoes, or offer three different vegetables. These are just examples.

Turkey: 40 pounds. So four 10 pounders, three 14 pounders, etc.

Dry mix stuffing: 40 ounces dry, so seven boxes. A lot of people go heavy on stuffing and it’s cheap and easy, so having extra won’t hurt. I’ve found the in-house brands like Walmart are just as good as the big name product and cost half as much.

Potatoes for mashing: 240 ounces raw. So 15 pounds of russets, peeled, cooked, mashed, and prepared as you like with milk, butter, salt, pepper, garlic, etc.

Sweet potatoes: 240 raw ounces. So 15 pounds prepared as you prefer.

Canned cranberry sauce: 160 ounces, so ten or twelve 14 oz cans. These could be split between cranberry jelly and whole cranberry sauce. Some people like one and not the other.

Pie: 40 pieces. For big pieces you’ll need seven pies, smaller pieces, 5 pies.

Butternut squash: 280 oz raw whole squash (17 pounds)

Brussels sprouts: 100 oz raw (6-1/4 pounds)

Green beans: 160 oz (canned), so ten or twelve 14 oz cans. When cooking raw whole beans, I figure six beans per person. A pound of raw beans is 35 to 40 beans. For 40 guests you need to cook about six pounds.


You can save money by buying larger cans. In supermarkets, verify that the larger container is actually cheaper. Many times I’ve seen a gallon jar of mayonnaise or other product priced higher than buying the same amount in several smaller jars.

Larger towns have stores that sell wholesale foods to churches and other organizations, and sometimes to the public. Here you can buy Number 10 cans (institutional size) that contain around 115 ounces, and save even more money.

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