I’m working on a future money-losing project in my spare time: a nice letterpress card that helps readers convert fractions to both decimals and metric measurements. Sure, you can make these conversions on your phone, but I prefer to see all the data at once, especially when trying to decide what size drill bit I need for a tricky peg.
Plus, it’s a fun graphic design project for that part of my brain that doesn’t get as much use these days.
As part of my research, I bought a bunch of old promotional posters. The things that salespeople would hand out to customers when they came to call. But my favorite find is this 1972 small slide chart from the Slide Chart Corp.
As the U.S. geared up to switch to the metric system, these sorts of calculators were everywhere. This one was a sample, made to show how you could get it customized with your company’s logo.
The slide chart makes 19 different calculations, plus has a graph that shows the difference between Fahrenheit and Celcius. It’s almost useful. It converts inches and centimeters, which isn’t quite what woodworkers need (I’d prefer inches to millimeters).
But it’s fun to play with, and I’ll keep it at my desk.
The best part is the little slide window that converts horsepower to metric horsepower. Are metric horses stronger? Look for yourself.
— Christopher Schwarz
P.S. I hope to have this letterpress card available for the holidays.
I love these kind of things!
Love the idea and the example you showed. Growing up in Canada we committed to the metric switch. Living in the states I always find myself in between. Hate getting out my phone to look up a conversion mid work.
In engineering school in the 70’s everything was metric. When you work through problems you get a feel for how things work. When I got into industry they said the hell with metric. The metric education ruined my brain.
Metric is easy. You just double it add 30. I learned that from Bob and Doug McKenzie.
“Like how many beers would that be, if you want like, a sixpack in metric?”
“Six, six is 12, 30 is 42 beers. 42 metric beers.”
I can get behind that conversion!
Let’s crack one of them open 🙂
I like it, I actually printed a small slide, eh, circle for such calculations. Bloody useless, but I wrote it in postscript (yes, the printer language) as an exercise. Fractions to mm I mostly remember…
I think you hooked Chris with that one!
Truly behind and ahead of your time.
Marvelous idea for old folks like us. Do be sure to use large print.
The US uses metric? In my early woodworking days I figured I’d pick one system and stick with it: inches. This was just because lumber in Canada is sold in inches. N. America is still odd: try to buy a chisel. Invariably you will be offered one in mm. It’s like languages – sure you can learn more, but getting good in one might be a better investment.
They wanted to switch, but then chickened out just moments before. Having spent time in Britain and Canada, the differences in Gallons confused me.
I remember receiving a slide chart from British Petroleum after they bought Gulf and sent out their branded gas credit card. It calculated your miles per gallon and kilometer per liter. It was fun.
I think they’re very slightly weaker.
Metric horsepower is one of those ridiculous and unnecessary units that i think metric and imperial people can all agree should never have been invented.
Historically, James Watt cheated on ‘horsepower’ to make his steam engines look better to mine owners. A ‘horse’ in ‘horsepower’ is a very small, asthmatic, anaemic pony with bad arthritis and the ‘Flu.
I want one!
Very handy item, I will buy one for sure. Thanks.
that card is build for someone like me. I live in a metric country (Israel) and am a slave to US imperialisms – when all the online info and best tools are imperial I ended up going that way too.
would definitely come in handy
You sir,are a rockstar! I absolutely love your writing style and sense of humor!
Believe it or not, there is museum for these things, may be worth a browse –
https://www.sliderulemuseum.com/Slidecharts.htm
Yes, please.
Probably because german horses are stronger than American horses.
Just yesterday I went shopping for a screw gauge. Thought it was just the kind of goofy thing you or Joel at TFWW would have, but I ended up going vintage on eBay. Turns out, they’re not easy to find, but I’ve gotta sort through those baby food jars of screws some day.
Dave, I too have the old screw thread gauges, Moore & Wright Metric and Unified, I was brought up on metric but there was still an abundance of unified fixings available, sorting those jars of screws is good therapy in keeping things tidy, I discovered a fair amount of BA fixings in the jars too. As I left school in 1974 we were just changing from imperial to metric so became familiar with both systems to the point that on some of my projects I still use imperial, room dims etc, with imperial you only have 2 sets of numbers to remember, feet and inches, in metric you have invariably 3 or 4 figures to recall, a room size 2450 x 3670 for example, easy to get the figures mixed up.
This is a good idea. I would buy it. When I was in fifth grade one a friendly class game. The teacher would always let the winner pick from a pencil box full of various prizes. Most of which were little plastic gadgets, erasers, or such. There was one metric/standard conversion wheel with various measurements ranging between length, weight and volume. I picked that, and I watched as the teacher rolled her eyes.
Edit- meant to say “I won a class game”. Foiled by talk to text and no reading glasses.
Am I mistaken, or does it take 81 metric horses to match 80 of our good old imperial horses… only if they’re the same number of “hands” tall. Are there metric hands?
81/80 is also the frequency ratio for the syntonic comma– the most raunchy out of tune awful sound you will ever hear.
That converter card would be just what this neanderthal needs in his shop apron!
I vote for a secret decoder ring metric converter.
the feet in that card are divided by 10ths…..
Ask me about my SLIDE RULE collection! Wood, plastic, pocket size. I’ve got a toolbox drawer full of them!
I’ll buy one! I fondly remember my slide rules from the days of yore. 🙂
I for one will be using the measurements of the king we deposed 247 years ago, thank you very much! My truck gets 40 rods to the hogshead and I like it that way!
Wrong King. The Imperial in Imperial Measurements goes back to Augustus, Julius Caesar’s nephew and First Roman Emperor. Big Julie and later Octavian (Augustus) had a big campaign to ‘reform’ Roman weights and measures. Just be grateful they didn’t go with the Greek system or you’d have 16 fingers to the foot instead of 12 thumbs, which is much more useful.
Not often you read the mention of “letterpress” in any publication any longer. Looking forward to the finished product. An “ancient” former letterpress man.
We have done several letterpress projects through the years, including two posters and an entire book, “Roman Workbenches.” We love letterpress.
Be sure to include conversion for millibars to inches Mercury do we can be aware of atmospheric conditions affecting our wood. Thanks
There is a handy inches to mm conversion tool readily available. Those plastic vernier calipers that have a fractional inches (Imperial) scale on the top and a metric scale on the bottom. Every time I do a measurement the result is presented in both inches and metric, in a linear manner that gives an idea of relative magnitude.
Readily available on Amazon.
Need millimeters and centimeters please and thank you
Wonderful idea! For a bunch of things, actually. Good on ya!
I… I just…
Gah.
I feel incomparably rude for even asking…
Do you not have some of these by your drill press?
https://taytools.com/products/starrett-pocket-card-decimal-equivanalts-and-metric-conversions
I have one of these… somewhere. At one time I imagine that Starrett gave these away. Not surprised that they cost $10 now
Grand idea! I could use it for a bunch of different stuff. Please do this!
You have my official endorsement for this project. The mph to cm/sec conversion will be great for old folks who want to feel better about slowing down, but the mph scale must extend into the fractual zone.
Are you.. Are you really thinking of a letterpress nomograph? There was a Dead Reckonings calendar that featured a wide variety of these things a few years back. Yours could be a combination chair-monkey and BMI calculator on one side, and the other side devoted to converting metric to imperial stouts. This seems like a slippery slope in multiple dimensions.
It seems that most of the commenters are too young to remember how imminent the adoption of the metric system was in the US. In engineering school in the early 1970’s we were required to work our problems in both systems, Imperial and Metric. The belief truly was that by the time we entered the working world this would be how we would need to work. In the Imperial (better known as the English back then) so that “old” engineers would be able to understand the calculations and Metric to meet the new industrial requirements. Well you can see where that went. Although I had a Chrysler product that was a mix of Metric and Imperial fasteners in the mid-1980’s
No such thing as Metric horsepower! Horsehockey!
Malcolm, are you jesting (joking) about the Metric Horsepower ? I’m in the UK and the term Horsepower has been around for many decades, I recall a term Brake Horsepower years ago but not sure what that means, anyway back to Metric ? horsepower, the automobile industry had always quoted vehicle power in HP (horsepower) and around 15 years ago they started to introduce a new term called PS, I investigated and found PS was Pferdestarke, a German word for horsepower, 1 PS equates to around 735 Watts whereas 1 Horsepower is 745 Watts so they are very similar, I often wondered what you would call the PS term and of the top of my head coined it ‘Metric Horsepower’, only because the Germans are in Europe and metric is the system used there, so here we are, a common line of thought as borne out in one of the other posts.
Don’t get me wrong or think I’m trying to be smart or something, just thought I’d convey the idea of common thinking.
Need to understand the horsepower definition. It is the amount of force to raise a defined weight a defined distance in a defined time. The final difference between Imperial and Metric calculations is that the weight and distance are in the respective systems units, resulting in a slightly different result.
Also as a former gearhead, BHP vs HP to my understanding BHP is when on a dynamometer the hp is measured when a resistance is applied to the output shaft. American car builders have used the hp number for a long time which gives them a higher number for a given engine versus BHP.
This is very similar to the hp values reported for electric motors. One noted US retailer always reported hp at stall which is different/higher from what you see when using the saw or other tool.
I’m not quite sure why there is a difference in the rated watts of metric and imperial horsepower, don’t think it is because the weight units are in pounds and kilos but I could be wrong.
The BHP, I seem to recall someone informing me the setup is with a load added as you say.
I rarely need to convert to metric or back. I do however find myself dividing fractions and have to grab the Calc for that. Like if I have 18 9/16 opening and need to divide it by 5 as an example. (I’m aware of dividers and the By Hand and Eye stuff – I’m getting better at that), but I’ve often wondered about a slide-rule type thingy that could do this easier and quicker. Anyway…
I wonder how many, if any, readers know what “letterpress” is?
Howard…
I have a nice slide card from the era that has INCH/MM/CM on a single scale.
Am I the only one thinking that April Fool’s Day came early in Covington this year? Steve
Yes.
My wife is from Sweden. When remodeling our house she wanted to help with the framing, So, I grabbed 2 metric tapes from the hardware store. “Ok… We need 18 studs at 2.44m, and mark the top/bottom plates at .41cm O.C. Start at the left end and put andX mark to the right of you line.” we framed the whole darned thing in metric. Lo and behold it hasn’t even fallen down yet. I will buy one of those converters!
Sure that isn’t .41 m on?
.41 m OC (stupid autocorrect)
No
No. 🙂
What does ‘available for the holidays’ mean? Easter holidays? Summer holidays? Some other holidays?
It could only mean Arbor Day.
I have a great little card magneted to a metal cabinet in my shop. Shows all the numbered drill bits, all the metric sizes, and all the fractional sizes in order from smallest to largest. I use the chart all the time for all kinds of purposes, not just drill bit sizing. What I would like is a larger card, that I can actually read without fumbling for the cheaters. And printed well, so it’s easier to read. With a thoughtful font choice.
It might be nice if common screw size pilot holes were suggested? I’m sure there’s other similar information that could add to such a chart, without overload – to make it even more useful.
I wonder if a seperate chart showing common rises-over-runs of various angles would be useful, so I can put away my brain trying to do trig? How about a chart showing some common design proportions, like the Golden Ratio, the Fibonacci series, and etc?
And if you entered into a co-marketing agreement with some of your favorite people, they could kinda be like the old manufacturers’ advertising, “Complements of Colonial Homestead”, or etc. Would be quaint, and fill my life, or my shop, with more reminders of people I like, and fewer of anonymous international tool conglomerates. Maybe a brewery would sponsor such an item …
my favorite is missing from the calculator “metric butt ton”.
Shouldn’t there be Joules and Pascals for energy and pressure?
Maybe you could sell your letterpress card to the guys who keep sending me the drill speed and screw guide chart.