Search found 656 matches

by rudd
Thu Feb 06, 2020 6:57 pm
Forum: Live Steam
Topic: Necessity of hardened crank pins on 3/4” scale
Replies: 48
Views: 3539

Re: Necessity of hardened crank pins on 3/4” scale

What you should take away from this is that it is NOT a tolerance issue. It is an engineering issue, one of not choosing a size that will provide the necessary clearance to compensate for the undulation of the engine as it moves along a not so perfect track. H Which is exactly what I intended to co...
by rudd
Tue Feb 04, 2020 8:37 pm
Forum: Live Steam
Topic: Necessity of hardened crank pins on 3/4” scale
Replies: 48
Views: 3539

Re: Necessity of hardened crank pins on 3/4” scale

I don't think this is the correct takeaway. It seems you are mixing up clearance with tolerance. They are not the same. I'm surprised others have not chimed in here, as this has been covered here on Chaski before. OK, I'm not sure what you think I don't understand here. Tolerance in my shop is the ...
by rudd
Mon Feb 03, 2020 8:21 pm
Forum: Live Steam
Topic: steam/exhaust port sizing
Replies: 4
Views: 1024

Re: steam/exhaust port sizing

Yes, that is what I have. Did not know where it came from though. This is for a smaller 7 1/2" gauge loke, cylinders and saddle are grey cast iron. Say larger than a Fitchburg but smaller than a standard Mogul. They'll be silver soldered together. The port areas I have in the drawings now proportion...
by rudd
Mon Feb 03, 2020 6:51 pm
Forum: Live Steam
Topic: Necessity of hardened crank pins on 3/4” scale
Replies: 48
Views: 3539

Re: Necessity of hardened crank pins on 3/4” scale

Good advice. I learned this from my first mentor, the chief inspector for an aerospace tool & die works. He built his first locomotive to "plant" tolerances and it wouldn't run. As soon a one end of a part heated up and the other end of it didn't, things locked up solid. Relieving almost every slid...
by rudd
Sun Feb 02, 2020 8:35 pm
Forum: Live Steam
Topic: steam/exhaust port sizing
Replies: 4
Views: 1024

steam/exhaust port sizing

I've been reading the RRSC "engineering manual" and also some old steam engine design books based on full scale practice. RRSC manual states ports should be at least .4 * diameter of cylinder long, then backs into width. The .4 factor is based on making cores that will stay during a pour. Writer end...
by rudd
Fri Jan 24, 2020 9:37 pm
Forum: General Discussion
Topic: Removing End Of Broken Pipe From Pressure Pot Manifold
Replies: 28
Views: 1834

Re: Removing End Of Broken Pipe From Pressure Pot Manifold

Looks like there is a little bit of pipe proud of the female part. Hacksaw blade to top of threads, take a punch and collapse the pipe. If you can get it started collapsing, you've got it.
by rudd
Tue Jan 14, 2020 9:36 pm
Forum: Live Steam
Topic: CSME Double Tracking Progress
Replies: 13
Views: 5029

Re: CSME Double Tracking Progress

What a beautiful place for a RR.
by rudd
Sat Jan 11, 2020 8:39 pm
Forum: General Discussion
Topic: heat shrink fit
Replies: 36
Views: 3049

Re: heat shrink fit

One thing I considered after looking at Liveaboard's post at the top - that red hot block is going to transfer quite a bit of heat into the shaft. The block is then going to shrink, with the shaft being the last to cool. I think it's quite possible the shaft will be "shrunk" by this, leading to less...
by rudd
Tue Dec 31, 2019 3:57 pm
Forum: Live Steam
Topic: Worthington Duplex pump & Brass Hex head screws
Replies: 27
Views: 3410

Re: Worthington Duplex pump & Brass Hex head screws

These folks bought out American Model Engineering, which made imperial sized miniature fasteners. http://www.godshallscustommachining.com/american-model-engineering-supply.html Here's the catalogue from the original website. http://www.americanmodeleng.com/id14.html Here's a place with metric and im...
by rudd
Tue Dec 31, 2019 3:39 pm
Forum: Live Steam
Topic: Allen Mogul: Packing in saddle assembly?
Replies: 12
Views: 2162

Re: Allen Mogul: Packing in saddle assembly?

used moulding sand. A core that the foundry was too lazy to remove after the casting was poured? Possibly, but this casting had a steel plate bolted onto the bottom that was the whole size of the saddle, and the sand was packed around the steam/exhaust pipes. The sand was tight against the steel pl...
by rudd
Mon Dec 30, 2019 8:25 pm
Forum: Riding Scale Railroading
Topic: 0-6-0 diesel yard switcher
Replies: 15
Views: 4168

Re: 0-6-0 diesel yard switcher

Going back to college physics, we were all a bit surprised to learn that the area of contact was not a factor in the equation for friction. Friction is calculated simply Frictional force = force normal to the plane x coefficient of friction. Axle loading is a real good reason to have more axles thou...
by rudd
Mon Dec 30, 2019 8:05 pm
Forum: Live Steam
Topic: Allen Mogul: Packing in saddle assembly?
Replies: 12
Views: 2162

Re: Allen Mogul: Packing in saddle assembly?

In 12" = 1'-0" scale, we had a little Porter 0-4-0T at the museum - I mean TINY for standard gauge. That area was packed full of what I now believe was used moulding sand. It was really hard to dig out. The smokebox was open to the cavity for the steam & exhaust piping, so the sand was probably the ...