ali tube bender - around 50mm[2in] dia and about 3mm[1/8th-in] thk

He's expecting sizes 50mm and 42mm, wall-thk. 3mm to 4mm That's 2inch and 1 21/32nd inch diameter, 1/8th inch to 5/32nd wall.

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Customary US practice is to dimension and measure wood to fractions and cut or drill visually to marks, metal to decimals and work to DRO or leadscrew dial readings. Not knowing that, early import milling machines sometimes had

8 TPI leadscrews, 0.125" per turn. They are a real nuisance to use without a DRO unless you've memorized fractional equivalents.

Many things sold in the USA as inch sizes are actually metric, chain for instance. Tubing size is actual measurement, pipe is nominal size, based on thicker-walled wrought iron pipe for early steam power, and the size doesn't match any measurement.

An engineer friend converted John Browning's drawings for the .50 machine gun from 128ths to decimals. Foreign designs we manufactured during WW2, the Merlin engine, Bofors and Hotchkiss AA guns, had to be completely redrawn to US standards including much tighter tolerances to eliminate hand fitting.

There are tables for bending radius of various size tube. Many of the available bending dies are larger than the minimum bending radius for a particular size tube, but that also depends on wall thickness. Contrary to popular belief, a thicker wall tube is supposed to bend more consistently than a thinner wall tube without kinking.

Jim is right in that tube diameter and pipe diameter are very different. Tube diameter is very close to the stated diameter. For pipe diameter, if you don't have it on hand to measure, there are lookup tables.

Since you mentioned diameter specifically, I assume you are talking about round tube but, square tube is also bent. You have to put a crease on the inside side wall.

The die needs to be a tight fit to the tube, and lubrication is a big help. Of course, remember that some types of metal will work harden including aluminum.

Depending on the type of Bender and the tightness of the radius, you can often get good bends without one, but there is a way of bending using a mandrill on a rod inside the tube that helps reduce the distortion in shape.

HEY! Posting from Newsgrouper worked! Woo! Hoo!

I've heard of that. The USA had this "production engineering" which shifted a massive amoutn of things and moved the price to vastly open-up the market - "a virtuous circle" at those times. Ford Motor Company in Britain were bemused by Rolls-Royce aero-engine tolerance on drawings - their production cars were made to much tighter tolerances... Thing is, we did have a very developed engine, and when hostilities started that was the engine we mass-manufactured - or had manufactured for us - "like shelling peas".

I took a friend of mine to Kelham Island Industrial Museum this Winter/Christmas, and there is the one-and-only drop forging die set for Merlin engine crankshafts during the Battle of Britain... It's "vastiferous" how much of history formed around that.

I've heard of that. The USA had this "production engineering" which shifted a massive amoutn of things and moved the price to vastly open-up the market - "a virtuous circle" at those times. Ford Motor Company in Britain were bemused by Rolls-Royce aero-engine tolerance on drawings - their production cars were made to much tighter tolerances... Thing is, we did have a very developed engine, and when hostilities started that was the engine we mass-manufactured - or had manufactured for us - "like shelling peas".

I took a friend of mine to Kelham Island Industrial Museum this Winter/Christmas, and there is the one-and-only drop forging die set for Merlin engine crankshafts during the Battle of Britain... It's "vastiferous" how much of history formed around that.

------------------------------- You had the labor force to do the hand fitting. We never did, immigrants headed for land on the frontier. Our urban architecture is much plainer for lack of hungry artisans. Labor-saving automation was necessary here from the start, by Eli Whitney, Simeon North & co. Henry Ford had begun as a watch maker, an industry that excelled in precise mass production tolerance.

"North is now generally credited with the invention of the milling machine, the first entirely new type of machine invented in America and one which, by replacing filing, made the production of interchangeable parts practicable."

The Merlin and Allison engines were mechanically comparable, the difference is RR had in Hooker a fluid dynamics genius to improve the air flow and Allison didn't, mixture distribution was a continuing problem on the Allison.

Military contracts offered an advance to purchase production machinery that would make interchangeable parts to simplify field repair. Otherwise a gunsmith would have to custom fit and harden spares made under or oversized. Before bicycles, sewing machines and typewriters military firearms were the only high volume tight tolerance steel product with a guaranteed production run.

This was invented to machine twist drill flutes for firearms manufacture.

"Universal" means the table swivels horizontally, to mill at angles. The indexer rotates the work in sync with table travel to cut a spiral.

When I visited it was stored upstairs. When the manager saw I was taking photos with a 1936 Leica he brought out his own, chatted, and then let me wander through the storage rooms. I identified the machines from pictures in this:

Another treasure from an arms maker up there was an automatic lathe, invented by Christopher Spencer who produced the most used US Civil War assault rifle. 's a general purpose turret lathe operated by a slowly revolving drum underneath surfaced with bolt-on cam plates instead of an operator on a lever.

I had heard that the primary thing that defeated the Zero was evaluation of a captured wreck where they discovered that the pilots likely didn't have the strength to muscle the controls against torque in certain maneuvers. It meant they ALWAYS turned the other way making it easy to predict and the Zero would travel right across the allied pilot's gun sights. Bob La Londe CNC Molds N Stuff

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reports on the Zero from China were ignored.

It had several weaknesses that resulted from its light weight and strength margin of only 1.5X, less than the standard of the time. The idea was if it could turn tighter than any other fighter it didn't need the weight of protection from the rear. It's been called the ultimate WW1 fighter. Japan wasn't alone in assuming the next war would be an extension of WW1. There was relatively little advancement during the 20's and 30's, Germany, Italy, Britain and Russia began the war with biplanes still in combat use.

I have designer Horikoshi's book on creating the Zero, in which he details the difficulty of making a new higher performing plane as nimble as an older, lighter one. He was watching a high speed dive test when the plane loudly broke apart from stress and plunged into the sea along with the pilot. That caused the diving speed limitation, some US planes were faster in level flight. At high enough dive speed air pressure froze the controls and prevented maneuvering, the reason why a kamikaze had to be destroyed with 40mm or 5" cannon shells instead of just killing the pilot.

On rec.aviation.military I discussed the book with Erik Shilling who had been the engineering officer of the Flying Tigers in China. He claimed they fought Zeros, or Army Zeros, there's evidence at least some may have been the very similar and even lighter and more nimble Ki-43 Oscar, which lacked the Zero's carrier landing reinforcement and 20mm cannons.

Horikoshi was very proud of his work but not to the extent of making excessive claims, he also described the problems that aero engineering in Japan faced; inflexible demands, limited materials, too few skilled technicians and high power engine development issues they didn't have a stress and vibration genius like Stephen Timoshenko to solve.

Germany had a similar problem of drafting too many scientists, engineers and technicians. I think some of the wilder proposals for wonder weapons were merely self-preservation attempts. We argued that on r.a.m. with two Nazi supporters who claimed they could have won if only the war had lasted a little longer. The general who commanded the jet fighters had stated if he could have stopped the Allied bombing the Russians would have simply conquered further west. mind that the 1200+ jet fighters they did build had little effect, and couldn't even defend their own airfields. AA fire became the main danger to bombers.

This is a good description of the problems and solutions in powering a plane at high altitude:

The drawings are of an Allison engine in a P-40 which was designed for and excelled at low level infantry support, and had a sea level supercharger that was effective up to 15,000 feet. Due to higher altitude power loss a P-40 needed half an hour to reach 30,000 feet, making it useless over Britain. The engine has to be throttled down at low altitudes to limit manifold pressure and avoid damaging preignition, "knock".

WW1 had ended all European wars. During the Depression there was no extra money to plan to fight overseas and insufficient risk of threat from high altitude enemy bombers. Enemy carrier planes such as torpedo and dive bombers operate at low level, P-40s shot some down at Pearl Harbor.

The bulk of the P-47 was needed to contain its turbocharger ducting. The P-38 was an out-of-the-box design that avoided Army fighter specification restrictions by creating a new class of "interceptor" instead.