Why Don't "They" Make ......

[BigBoy1]

I'm involved in my first big project where I'm making the drawings and then machining the items. I'm really getting fed-up with the darn fractional dimensioning system. It really is not a user friendly system. Also, as I understand, it was fostered by the wood workers and it has been addopted by metal workers.

My question is why don't "they" make machining tools, i.e. milling cutters, drills, etc. in even numbered decimal inches? Instead of specifing a 3/32", why not use a tool 0.100" in dimension; a 0.200" tool instead of a 13/64", etc.? It sure would make dimessioning much easier and halfing if dimensions a whole lot easier.

Just my ramblings on this rainiong morning!!!!

Bill

[paulx]

Why not go metric.

[BobC]

Ditto on the metric. It would be so much simpler.

[dirty old man]

For those of you who are young, just starting out in the world of machining and otherwise working with tools, and other things to which measurements apply, I'll grudgingly admit that metrics could be a good way to go.
But to old farts like me (next birthday will be 70), metrics are a PITA and a costly thing.
After a lifetime of gathering tools, machines, etc. now I am having not only to learn metric measurement, but buy tools, machines, etc. again or be left in the dust.
All sorts of wrenches, many of them expensive special ones won't work on newer vehicles because of metrics, mics and other measuring tools are a PITA to use as you must convert the dimensions or the measuements, drill bits, reamers, taps, dies, and the buckets of bolts you have collected in a lifetime are useless.
And to top it off 3 perfectly good lathes are becoming obsolete because they don't cut metric threads and it would take more labor than they are worth to design and build conversions for them.
No, I don't think you want to ask me what to do with metrics.
Dave

[Swarf&Sparks]

Unless you plan to try single point threading in metric, on an imperial lathe; why worry?

Design in metric, use metric drills, tools and fasteners.
It's about time the USA got over its aversion.
I prefer to grab a 12mm drill but I can still use a 31/64 in a pinch.
It's a lot easier on my 50 YO eyes, to read calipers (yes, verniers) in 0.01mm for a quick check than all the confusing lines on the inch side.

Lest you think I'm some euro Jean-come-lately, I grew up with and am comfortable in both systems.
The grief comes when you try to convert.
Worse still, is when you change horses in mid-stream.

Regards, and good luck with the project,
Lin.

[pcarpenter]

I'm not sure how we got from fractionals vs. decimals all the way to completely switching systems of measurement. I'm also one of those folks who grew up with both and it clearly did not *reduce* the number of things I gotta know. In addition to knowing that 1/16=.0625, I have to know that 2.54cm= 1 inch. That's more difficult, not less. There is a saying that says "that's the great thing about standards....there's so many to choose from". We didn't get a replacement standard when we here in the US tried to adopt the metric system, we got *another* standard.

The trouble is that "Embracing" the metric system will inherently be a switching of horses mid stream. We have lots of stuff like machine tools, indicators, etc that would all have to be replaced and that is no small matter.

I guess I also don't understand your statement about single point threading (is there really any other kind for most of us?) on an imperial lathe. Many of us have imperial lathes. We do single point threading. If we "embraced" the metric system, we would need to be cutting metric threads on that imperial lathe....which was exactly the point.

Heading back to the original topic, however, the use of standard fractionals is not so terribly difficult. If a decimal equivalent chart (I have them on about every wall in my shop) is not your bag, learn the standard values for the lowest fractional increments and then you just need to add and multiply.

ie. 1/8= .125, 1/16= .0625 etc. From those you can know that 9/16=.5+.0625 or .5625 without the aid of a table. After working with them a bit, all the common stuff will be in your head anyway.

paul

[Swarf&Sparks]

Kinda my point, Paul.
If you are designing a part you have to single-point, you use the native system of your machine. If you are just drilling and tapping holes, or measuring and cutting, use what you're comfortable with.

Me, I stick with metric coarse. M4, 6 & 10 taps and dies cover 99% of what I do. And fasteners are available in almost any head and material, just up the road.

OK, I confess. I'm using 1/4 20 UNC allthread feed screws on my little CNC engraver/router

[J Tiers]

Well everyone knows that imperial measurements are ONLY in fractions.

Everyone knows that IS what the US system is, and is why it is so difficult to work with US/Imperial measurements.

Everyone knows that Metric solves that problem by using decimals.

Everyone knows that you CAN'T use decimals in the imperial system, it is impossible.

That's what everyone knows................

The rest of us wonder why anyone would use fractional measurements when all the dials on your machine are calibrated in decimal inches.

The rest of us wonder why anyone would use fractional measurements when all the dials on your dial calipers and micrometers are calibrated in decimal inches.

The rest of us wonder why anyone would use fractional measurements when US metalworkers have used decimal inches (or metric, yes) for 100 years.

[Swarf&Sparks]

Yup, and still make 31/64th drills

[John Stevenson]

When China decides to only supply in metric to simplify production to the rest of the world, the US will have to change, after all if it's not manufacturing anything it can't support imperial.

OK only said in jest but what would happen if HF, MSC, Jet and Grizzly were only able to source metric machines from China ?

When I was over in China, on the Seig stand they had a C4 lathe

Nice little thing, 8-1/4" swing by 18 between centres, power to carriage and cross slide but it was all metric.
I asked about an imperial version for the UK but was told no. I then pointed out that they needed an imperial version for US markets but their answer was metric or don't bother, they can sell enough in metric countries not to warrant having two models.

.