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Re: Amazing machine work

Posted: Sat May 18, 2019 5:58 pm
by Cary Stewart
Those gears are not the same as the ones that my father inspected during WWII at Lockheed but they are of the same quality. He was a precision parts inspector on the P-38 line. His responsibility was for the turbo charger gears for the P-38. The shop was having trouble meeting the prints requirements and the shop foreman went to my father and asked him to start passing more of the gears coming out of his shop as he was getting behind in deliveries. Apparently the shop was manned my non machinist machine operators and as the gears were made of stainless their out put was not to spec. My dad told him to do one of a few fixes. Get his workers to learn to machine to print, go to the engineer who signed the print and get changes to the tolerances, or continue and make more scrap. The foreman stormed off after telling my dad that he would get him. I never heard a name mentioned but this was a very good lesson in honesty and integrity that my father told me in about 1946. I was 10 years old then.
Cary

Re: Amazing machine work

Posted: Sat May 18, 2019 6:05 pm
by Cary Stewart
There were two engines that were based on the Merlin. The Allison and the Packard. The first P-51s had the Allison. They flew well but were underperforming. The English got a batch of 5 or 6 of the early ones. A test pilot thought that the plane flew well but was under powered. He suggested that a Merlin be installed in one of them and test flown. With the Merlin the P-51 became a world beater. It took a year before the Brits could convince the USAAF to change to the Packard. Then the Germans discovered that we had a better airplane than theirs. It's coke bottle shape is what made it much more fuel efficient than the Spitfire, P-38 & Thunderbolt.
Cary

Re: Amazing machine work

Posted: Sat May 18, 2019 7:30 pm
by GlennW
The Packard wasn't based on the Merlin, it is a Merlin and was built by Packard under license from Rolls Royce to keep up with the high demand. British built aircraft were supplied by Rolls Royce and production built aircraft built on the North American Continent were supplied by Packard. Continental also made a small batch of Merlins under License.

Other than being a twelve cylinder inline engine, the Alison was built by General Motors and is a completely different engine.

Re: Amazing machine work

Posted: Sat Jun 01, 2019 2:15 pm
by Glenn Brooks
Glenn, indeed, in the mid 30’s Crystal Lake Grinders produced a cylindrical grinding machine capable of grinding parts to .000015”. I have one in the shop that I hope to find belts for and put to use one day.

http://crystallakegrinders.com/

When I crank the handle a few times to move the ways, can’t even tell the bed is in motion! Their first line of grinders was produced around 1910 or so - making small watch and typewriter parts.

Might be that early 1800’s machine tools suffered precision problems, but I think early day machinists were mostly limited by the capable of metrology tools available to them. Certainly 1/million” tolerance parts production was available prior to WW II.

Found this photo of my CL grinder, sitting forlornly in the corner of my shop. Still a cool old machine. The little roof over the top houses a fluorescent lamp and the motors and shaft. CL found that mounting the drive and grind motors a few feet above the ways reduced vibration a great deal. Then then connected the grinding wheels with the shaft with a very thin and flexible flat belt. Something like 1/8” thickness or less. Apparently innpart this enables the high tolerances the machine is noted for.


Glenn B.

Re: Amazing machine work

Posted: Fri Dec 13, 2019 11:31 pm
by pete
Beautiful pictures of some beautiful parts Glenn. I've seen a lot of those comments and the same perceptions about a lack of accuracy without today's modern machine tools. Afaik P&W is credited with the invention of the jig borer in 1913. Needed no doubt both for there aircraft engine production and improving the other machine tools used in that engine production. Given the shear number of parts, the accuracy and the volume of Packard and real RR Merlins produced and doing it all as fast as possible under WW II war time conditions that was a more than impressive effort. Doing the same today to that 5 decimal places would still be an impressive effort by anyone's standards.

Re: Amazing machine work

Posted: Sat Dec 14, 2019 7:20 pm
by tornitore45
Glen, I like the display and it even seems it has some kind of plan. That engine must have a gazilion parts. How do you put is back together with all those parts seemingly scattered.

Re: Amazing machine work

Posted: Sat Dec 14, 2019 8:56 pm
by GlennW
tornitore45 wrote:
Sat Dec 14, 2019 7:20 pm
That engine must have a gazilion parts.
Mauro, Including hardware, nearly 14,000 parts per engine.

I'm working on two of them right now, and having both of them apart at the same time is a bit more interesting! I usually only do one at a time. I started on a third, and decided to hold off on that one for now. :?

Re: Amazing machine work

Posted: Sun Dec 15, 2019 8:00 am
by tornitore45
Good plan, the 3rd engine may be the "blueprint" to put the other two back together. I was going to wish you good luck but I know your skills will assure the success.

A friend of mine made a 1/4 scale of the Merlin and is running.

Re: Amazing machine work

Posted: Sun Dec 15, 2019 10:07 am
by curtis cutter
I suspect Harold knows this location but in the central Western Washington area there is a natural gas underground storage facility where up to 45 billion CF of natural gas is impounded under pressure from three turbine pumps that are driven by what in essence are 737 aircraft engines.

Here is a PDF link with a facility description.

file:///C:/Users/nwrai/Downloads/052_Jackson_Prairie.pdf

Re: Amazing machine work

Posted: Sun Dec 15, 2019 12:27 pm
by EOsteam
Glenn,

How many hours do the engines accrue before overhaul? What determines when overhaul is necessary? Also what parts typically require replacement or refurbishment. My aircraft engine is a 6 cylinder horizontally opposed air cooled apparatus and I’m well familiar with its potential failure modes so I’m interested in the Packard/Merlin engines and what wears out and drives the decision to overhaul.

Harper

Re: Amazing machine work

Posted: Sun Dec 15, 2019 12:34 pm
by BigDumbDinosaur
curtis cutter wrote:
Sun Dec 15, 2019 10:07 am
Here is a PDF link with a facility description.

file:///C:/Users/nwrai/Downloads/052_Jackson_Prairie.pdf
A link pointing to a file ensconced on a hard drive isn't going work over the Internet. :D

Re: Amazing machine work

Posted: Sun Dec 15, 2019 12:44 pm
by BigDumbDinosaur
pete wrote:
Fri Dec 13, 2019 11:31 pm
Afaik P&W is credited with the invention of the jig borer in 1913.
There is some evidence that the jig borer was independently developed in Switzerland around the same time. P&W was the first large-scale user of the machine, well before they got involved with building aero engines.

A former employer of mine had a large jig borer capable of work with a piece of 8' × 12' tooling plate. Yours truly was known on more than one occasion to use the machine to assist in making welding jigs for fabricating race car frames. :D