Fuel Economy Calculation and Conversion

Calculate Miles per Gallon

I already put together a little post on how to calculate your fuel economy in miles per gallon (MPG), but not everyone is interested in that particular measurement. That's 'cause there are only a few countries who use the imperial system of measurement (feet, quarts, miles and gallons), so the phrase "miles per gallon" doesn't mean much to people who live outside the USA. 

Calculate Liters per 100 km

In most of the countries that use the metric system, people share their fuel economy with a number called l/100km, or liters per 100 kilometers instead of the MPG so familiar to people in the States. You just need two numbers to calculate l/100km, though the division is a little different from what you're used to.

Bicycle Maintenance 201: How to Change Your Chain

Why change what seems to be a perfectly good chain?

The answer’s actually simple: chains wear out and even break. That wouldn’t be a problem except that “wearing out” means a chain gets longer. Here’s why: 

The anatomy of a chain.

When a chain's new, the spaces between the rollers exactly match the spaces on your chainwheels and cogs (what most call front and rear “gears,” respectively). As the chain wears, the pins connecting the links (hidden inside the rollers) wear down and allow the chain to get slightly longer. This, in turn, grinds away at the teeth on the cogs, which changes the length of their spaces. If you have to install a new chain because the old one broke or a link froze up, the spaces will no longer match. That makes the new chain skip on the cog, and can wear out the chain faster than it should. Worst-case scenario, you may need a new cogset, which costs about three times as much as a new chain (and requires special tools to install). You probably don’t want that.

Repair a Hole in Drywall

Although it’s far more easily installed than plaster, a surface sheathed in drywall (also known as sheetrock, wallboard, and plasterboard) tends to be softer and more damage-prone than one built up with plaster. The damage ranges from the small dents and scrapes caused by doors or furniture to major holes. Though it's unsightly, damage like this can typically be repaired by competent homeowners with the right tools and sufficient patience. Here’s a rough outline of how to patch drywall.

Evaluate the Damage

Determine the extent of the damage. Holes in walls can be of any size, but generally fall into a simple classification. The smallest class is the punctures made by nails or other picture hangers; next come those dents and scratches that don't break the surface. The third class is small holes that crack the wallboard and tear the paper - Many of these, for unknown reasons, seem to be fist-sized. Last comes large holes that might be caused by falling objects or trapped pets. You'll need to approach repair with different techniques and tools depending on the size of the hole.

Assemble Your Tools

Whatever the size of the hole, you’ll eventually use a putty knife or wallboard knife. Wallboard knives are made in widths of about 6-12 inches; for large holes you may need two or three sizes. No wallboard repair can be made without at least some joint compound. Although your college dorm roommate repaired nail holes with white toothpaste, a small container of joint compound or latex spackle actually costs less than that tube of toothpaste. Collect an assortment of different grits of closed-coat sandpaper. To repair a large hole you’ll need additional tools like a ruler, a wallboard saw, and something to use as a patch.

Easy Do-it-Yourself Display Case for Models

When the Ms returned from a memorial service for her late father, she brought a dozen or so collectible models of Standard Oil trucks - not worth much in terms of cash (about $3.50 each on eBay) but full of sentimental value. She also had a little display case for Matchbox cars, but the trucks were too big for its little shelves. Thus came the request,. "Can you make something...?" Making the body of a case like this was no problem. Oh, sure, there was the usual question about making the joints: mitered, box, dovetail, butt… But, the overall dimensions and the general design were pretty much set in stone, including the desire for a hinged front that had to be mostly clear glass. I don't know about you, but I find making a frame for a glass door to be a major pain in the butt. So I decided to let someone else make it…

One Simple Trick

An ordinary picture frame (from
the Michaels website)

Yep, you guessed it, I stopped by my local craft store and bought a simple black wood picture frame. That became my ready-made face, including glass (and glazing points). All that was left was to measure the frame's outside dimensions and design a multiple-shelf display box to fit behind it. I bought six feet of 1 x 3 poplar and a quarter sheet of ¼-inch birch plywood. With a couple hours' work with the table saw and router and I had a case. I cut my shelves and back from the plywood and painted them black, like the picture frame. The poplar I stained with some leftover wood stain I had in the shop.