The Home Machinist!

Yes, I was afraid my memory regarding shrinkage was a bit off, hey 0.5% or 5%, close enough for some work, ha ha ha... I did remember that the shrinkage depended on the metal, so I get a few points right ? How about an A- for effort ? I fixed my original post to more closely match the old "rule...

Glenn, just remember that using an original cast piece as a pattern will result in a new part that is about 0.5-3% smaller than the original. All metals shrink when cooling in a mold. Patterns for cast parts are always about 0.5-3% bigger than the final desired part size. Percentage varies depending...

I am not aware of cast iron "work hardening" ? I have repaired bearing boxes where a steel shaft rubbed against the cast iron for an extended period of time due to a busted bearing. The wear spot on the cast iron was the same hardness as the rest of the cast iron. Once you start to rub aga...

Steaminten wrote; "In the wayback machine, it was known that switches and diamonds had to be watched for creep. A crossover for example on a double main, had the trains marching the rails in opposite directions." My Father was around back when the NYCRR had four track main lines, the vast ...

"He is talking about a 7-5/16" radius. you aren't going to get that with a ball turner or a compound." Well, you can in fact get that radius with the correct ball turner. And he did not say what machine size he had available. I have the tiny little Sherline lathe and I can do about a ...

Benjamin, Also, if your lathe has a compound tool slide (capable of rotating around a pivot point), and it is in good shape, you could try; Adjusting the tool point to the pivot point distance to the radius you want, you probably need to back off the compound slide all the way. Loosen (slightly) the...

They make proper tools for that, a radius/ball turning adapter for a lathe. Lots of varieties and prices; http://www.bing.com/images/search?q=lathe+radius+turning+attachment&id=0B571055F3C46871823C5F9CD40A9646255F5409&FORM=IQFRBA Or you can make your own. Depends on your time and dollar budg...

RH, I understand your application better now, thanks for the explanation. I think perhaps you are expecting too much out of a material like PVC pipe. It is extruded at high temps and as it cools lots of stress is "locked in". When heated again it's likely to do all kinds of weird things. I...

Boy if it was me I wouldn't go anywhere near a cadmium based solder unless nothing else would work. How about you buy, or build something like this; http://www.hotbend.com/ A simple propane based wide area torch to warm the PVC enough to bend it. No oil, no soldering, no worries about the oil flashi...

Well, if my prior suggestion about using HDPE does not work out you could try this; http://www.mcmaster.com/#standard-pvdf-sheets/=q97qgw PVDF is also slippery and good to about 285 F. But it costs more. I guess someone will just have to try out these materials and see what works ? :roll: Cheers, Ke...

Dick, "but that close to the ash pan would heat be a problem?" A very good point, I had not considered that aspect. The HDPE is good to ~ 180F. I guess you would have to take some temp measurements with an IR thermometer to see how hot it gets down by the trucks. There are other plastics w...

Steve; "So for my future education going forward if I wanted to change out the Aluminum journal boxes to something better you would suggest a tools steel or a good bronze would be a good choice for the journal boxes?" If it was me I would just keep the aluminum truck casting and journal bo...