p.m. castings

[deadcenter]

Hi fellow Machinists,
I recently purchased a redwing hit miss engine casting kit. When I was boring the cylinder and I noticed a different cutting sound (Harmonic) about 2 1/2" deep into the cut . After I was to size and measured the complete bore a section about 1/2 " was under by .001. a very hard spot. Next when I turned the cast crank the one crank pin inside web cut really nice while the other inside web was as hard as diamond, actual making some run out in the crank it self which I had to straighten out by putting It in the press. The worst of all was both fly wheel hubs. It was like it had been bored offset of center and a alloy plug had been pressed in them. while facing the ends prior to drilling you could actually see the different metal compositions. After drilling the bores .375 they were wobbled out to where I barely could get to size (.5) using my carbide boring bar. I have previously built a p.m. #6 steam engine and never had any problems with the castings. Can these castings be heated to anneal them? I was wondering if anyone else have run into these issues and what Foundry are they being made at.

 

[barnesrickw]

First off, I'm only giving my input as a guy who ran a CNC, not a machinist. On the cylinder bore, if you are using a long, narrow cutter, at 2" deep you are likely to get deflection in the shaft. This will cause a high pitched squeal and the portion of the bore farthest from collet will be smaller in diameter. On the flywheel, the hole in the casting does not represent the center of the casting. Don't try to drill, but use a boring bar as close to center as will work, then turn the outside. If the material is cast or gray iron, it will first off be dirty and unpleasant to work with. Secondly, because the outer surface of castings cools much faster than the inner, it can be very hard. Break the surface slowly, the rest should turn fine. Hope that's accurate and helps.

 

[Philipintexas]

I suppose no two sets of castings are the same but I made that engine and I was impressed with the quality of the castings. I never had any problem.

 

[Wizard69]

Hi fellow Machinists,
I recently purchased a redwing hit miss engine casting kit. When I was boring the cylinder and I noticed a different cutting sound (Harmonic) about 2 1/2" deep into the cut . After I was to size and measured the complete bore a section about 1/2 " was under by .001. a very hard spot. Next when I turned the cast crank the one crank pin inside web cut really nice while the other inside web was as hard as diamond, actual making some run out in the crank it self which I had to straighten out by putting It in the press. The worst of all was both fly wheel hubs. It was like it had been bored offset of center and a alloy plug had been pressed in them. while facing the ends prior to drilling you could actually see the different metal compositions. After drilling the bores .375 they were wobbled out to where I barely could get to size (.5) using my carbide boring bar. I have previously built a p.m. #6 steam engine and never had any problems with the castings. Can these castings be heated to anneal them? I was wondering if anyone else have run into these issues and what Foundry are they being made at.

Hard spots can be found in any casting. In an ideal world the casting is fully annealed but that might not help if some alloying materials got mixed into the melt.

 

[Philipintexas]

Have you contacted PM about a replacement part?

 

[purpleknif]

Where I work we do about 50% cast iron. A lot gepends on the foundry. Its not unusual to open up a large void or find "glass" or sand in them. We're talking complex 5 ton castings here. Glass or sand in a face you can usually grind under the finish and get a good part. Voids generally need welded. Not our problem unless they're not annealed .

 

[deadcenter]

No Phil the pieces were all usable so no real big deal. I haven't built many models just p.m.s #6 steam engine , so my cast iron experience isn't great. P.M. is great with customer service I was short a piece on the redwing kit and they sent it out fast and I sure like there prints and designs. Thanks all for your comments.
Ron