Valve gear parts for big boy

[Harold_V]

Andy, I'm assuming a 300 series of stainless? Which one?

Harold

[mjahn]

Its been a mix of 303 and 304. I think more 303 though.

[Harold_V]

Its been a mix of 303 and 304. I think more 303 though.

From the standpoint of machining, 303 is preferred, as it is a free machining grade (I prefer 303 to almost any other metal, assuming it must be machined). I was not aware that it was available in sheet form, however, thus my question. I have seen it in rectangular bar form, however.

Harold

[mjahn]

Your world hasn't been turned upside down, all the link motion parts except for the main reversing cranks started life as bar stock.

[Andypullen]

Your world hasn't been turned upside down, all the link motion parts except for the main reversing cranks started life as bar stock.

These are actually all bar stock. The main reversing arm is made from plate, round and square stock.

To answer your questions Harold; for the most part; the parts have been made of 303 stainless. It's available in round, flat and square. Matt's eccentric cranks are 304. Steve found a supplier in Reading, PA on ebay that has drops of various materials. They are listed as 304; but some are 303. I won't tell if you won't. The price is right, but they don't have a great selection. Steve supplied the majority of the material for his parts and most of the material came from this supplier.

I'm asking the customers to supply their material to save them some money. There is a local supplier that I use and I can pick the stuff up on my way home from work in the afternoons. That also saves shipping.

I made some eccentric rods out of hot rolled and they turned very nice as well.

Right now, I'm running some rods in cold rolled for another customer. See attached pic.

Andy Pullen

[Harold_V]

Very nice, Andy. Having CNC sure takes the work out of parts like that, and ensures the center dimensions are consistent.

Harold

[LivingLegend]

No criticism ment here....

But if it were me, I would wait until I finished the loco chassis with the boiler mounted (or weight added onto the chassis approximate to the boiler) and time the valve gear to determine the exact pin-to-pin dimension before machining the eccentric rods.

LL

[cbrew]

No criticism ment here....

But if it were me, I would wait until I finished the loco chassis with the boiler mounted (or weight added onto the chassis approximate to the boiler) and time the valve gear to determine the exact pin-to-pin dimension before machining the eccentric rods.

LL

LL do you really think a few thou would make much of a difference in the real world?

[mjahn]

LL,

The plan as last discussed is that Steve's locomotive will be timed with temporary eccentric rods once its running on air. Once we're ready down here the temp eccentrics will be shipped down here so that we can time MCRS-4 with them.

[Bruce_Mowbray]

No criticism ment here....

But if it were me, I would wait until I finished the loco chassis with the boiler mounted (or weight added onto the chassis approximate to the boiler) and time the valve gear to determine the exact pin-to-pin dimension before machining the eccentric rods.

LL

If the model has pedestal shoes, the rods can be made ahead of time. The shoes can be made so that the engine will tram square and in-line.

[Andypullen]

No criticism ment here....

But if it were me, I would wait until I finished the loco chassis with the boiler mounted (or weight added onto the chassis approximate to the boiler) and time the valve gear to determine the exact pin-to-pin dimension before machining the eccentric rods.

LL

If the model has pedestal shoes, the rods can be made ahead of time. The shoes can be made so that the engine will tram square and in-line.

Yup....Right on the money Bruce!

Steve is going to use adjustable eccentric rods to set his valves. That's why I haven't made them yet. I'm waiting on a dimension. The material is sawn oversize on the length.

Yeah Harold....the AGE-2 is doing a great job! I'm fiddling with another CAM package at work and so far it's working out ok. One of my neighbors is the local tech for it and he said he'd get me the post so I can use it, too. I'm using Esprit 2005 to draw the parts to get the points for the conversational programming and that is working out fine so far.

Andy Pullen

[LivingLegend]

Bruce....

Not talking about side/main rods. Assuming the engine does indeed have shoes, the drive axle center dimensions can indeed be adjusted to compensate for slight error in side rod pin centers.

I'm talking about eccentric rods specifically.... No matter how well the valve gear is laid out, the actual on engine dimension of the eccentric rod can vary from the design in order to get the valve travel correct. And that dimension could vary one side of the engine to the other.

Locomotive manufacturers would use an adjustable eccentric rod at the engine's erecting to set the valves and determine the actual eccentric rod pin centers. After that was accomplished the eccentric rods were completed. Eccentric rods made for one engine were not ment to interchange between other engines in the same class. You should note, this is why parts of the valve motion were stamped with the engine's number they were fitted to.... So they would not be swapped while shopped with an engine of the same class.

The attached photo, is of a still being erected C&O L2-class 4-6-4 in Baldwin's erecting hall having it's valve gear set. Note the adjustable eccentric rod being used.

LL