Piston Pin matterial

[borna]

Hello all,
I got this Chinese multi-cylinder engine, and during the assembly, I noticed that I am missing one piston pin. This is a picture of one set of piston, pin, and connecting rod. Since I decided not to wait for them to send me a piston pin, I’m planning to make my own. That said, the piston is aluminum, and the connecting rod is most likely brass or bronze. So, my question is: What material is best for making the piston pin? Can I use HSS? Should it be hardened or not? If HSS is not a good metal for it, please let me know what to use?

Thanks

 

[kuhncw]

You could use either a piece cut from a drill blank (HSS) or you could use drill rod or silver steel depending on what it is called in your area. Either water or oil hardening are ok and no need to harden the drill rod in this application.

Please let us know how this turns out and post a picture of your engine.

Regards.

Chuck

 

[borna]

You could use either a piece cut from a drill blank (HSS) or you could use drill rod or silver steel depending on what it is called in your area. Either water or oil hardening are ok and no need to harden the drill rod in this application.

Please let us know how this turns out and post a picture of your engine.

Regards.

Chuck

Thanks for the info. Since the diameter of the pin is 4mm exactly, this should work?
https://www.amazon.com/dp/B07SYYDTVZ/ref=ox_ya_os_product?th=1

 

[kuhncw]

That should work. A drill blank would cost less.

Chuck

 

[abby]

Quick question , why would you not harden the piston pin made from drill rod?

 

[kuhncw]

It is ok to harden the piston pin and necessary in full scale engines. Loads are light in our model engines and the engines usually don't run hundreds of hours. Again, either method is ok. Builder's choice.

Chuck

 

[rleete]

Even plain CRS is harder than the rod, so hardening would not be necessary.

 

[petertha]

Hardened dowel type pin should be fine, just check the tolerances. Some are +/- either side of nominal dimension depending on the application, some are plus & some are minus. Presumably the ends are 'plain' meaning no end features like a hole for softer scuff pads? If so, then if the stock has to be machined, hardened would present a few more challenges.

 

[Steamchick]

Even regular Mild steel is adequate for this application. Steel and Bronze are similar densities so balance should not be a significant problem.
BUT if you can get some hard brass or bronze that should be exactly the same mass as the Chinese pin.
However, (1) why not ask the supplier for a piston pin? (2) If that fails, "shout" at the supplier, saying you will give them a bad report on the web unless they finish the contract of delivering ALL the parts? - I have only had to do that once, but bad reports on the internet can really upset the Orientals, so they are quick to resolve issues in that case.
On models, some people are not concerned if the model shakes a bit. But this engine should be relatively smooth, and may be spoiled by using a steel pin instead of a Bronze pin. - You can only try that and see?
K2