Yea, we used to use the ball type and had the same experience. Hence why we switched to the valve action.. Has a felt tip, and works great and lasts forever as long as you store them on their side.
Yes, that is exactly what I am saying
--and I'm also saying that it is a VERY ROUTINE occurance
And the reason is because there are very specific process control requirements in place later down the line which eliminate minor surface imperfections such as scribed layout lines and such where they would otherwise cause problems with stress cracking etc.
BAC 5300 and BAC 5730 immediately come to mind--look them up....there are probably a few others that apply.
And for Christ sakes I worked there for nearly 15 years as a machinist on the factory floor running cnc and manual lathes and milling machines, tracer mills jig borers thread and ID as well as universal grinders, broaching machines, drill presses, vertical shapers ....basically the whole works and so you can rest assured that I'm not just pulling this shit out of my ass.
The Materials folk at work forbid graphite-filled grease, precisely because of galvanic corrosion. Molybdenum disulfide is OK.
The whole story is in the galvanic series of the metals: .
Joe Gwinn
Aha. I hadn't thought of graphite being a noble metal. That's what I get for not learning chemistry in school
Thanks, Joe.
A mate that was working on a supercar project recently said something similar. One of the biggest issues he became aware of with having a carbon fibre tub and other bits is that everything else in contact with it is potentially at risk so great care had to be taken by those dealing with that side of it to prevent it becoming an issue.
Interesting. I hadn't thought about galvanic corrosion with carbon fiber, either. I'll bet that's a challenge on any car that has to deal with rainy weather.
I *do* know enough to put down my graphite flyrod and get away from it during a thunderstorm. d8-)
Hey, the way I was showed at school was to use felt tip marker pens - theres good ones and crap ones - a good one will set you back about $5 and you keep this for your bestest layouts. Rest of the time, cheap crap ones at the markets are fine - they dry out quick, but are dirt cheap so you dont crack it when one gets lost. The good ones here are Japanese, (nope, now made in Malaysia, just looked at it) ARTLINE100 - its got a broad chisel tip so you can do lots of area if you need to. Washes off with CRC, Kero, Turps. Steel wool. But dont leave it on for years, it does set...
One day, when I am a real engineer, I will get some layout dye and make up a pot to keep near the workbench......but until then.... I will also keep the tube of Prussian Blue nearby for when I use the surface plate.....near the end of the layout bench......
Andrew VK3BFA.
Tell him you're buying it for his son. ;-)
Gunner Asch on Fri, 24 Jun 2011 00:32:28 -0700 typed in rec.crafts.metalworking the following:
Blue for cuts and alignment. Red for the scrap bin. As in "This right here is where it is out of spec, and cannot be fixed."
Sigh. I saw too much of that...
pyotr
So, do you do that kind of work in your home shop?
Do you recommend it for others at the home project level?
Sort of, though technically, I don't think I really qualify as a "home shop" these days.
Occasionally, I take on some 3rd party aerospace communications and defense work--usually it's one-off stuff and under a horribly compressed time schedule.
Pretty sure those days are long gone and probably that's not going to happen unless you have about 3/4 million dollars you'd like to invest up front.
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