Office of Steam Forum for Model & Toy Steam Gas & Hot Air Engines

I made a start on the outboard cylinder cover. A tricky item, being a somewhat thin casting. I turned the OD in 2 stages - from one end, then flipped around. I couldn't think of another way of doing it.

Since the part has to be machined down to a step, that more or less got rid of the line on the OD from the two stage turning, and the OD is close enough that when I clean and polish parts that mark will go away.

 



Mostly finished part. I actually need to skim the face and shave 3 thou of the small diameter. I didn't plan to do it this way, I had intended these turnings to be finished. However, since I am only a few thou oversize, I'll wait until the cylinder is done before dressing this up.



So I turned my attention to said cylinder. I have been scheming about this part for a while, so I decided to proceed.

Started by dressing some of the uglier bits of flash on the belt sander.



Then used a dead center to get the casting mostly straight in the chuck. There is plenty of material to get a clean bore, so this seems to be as precise as needed to start making datum faces.



I basically just did a minimum clean on each end, leaving plenty of material, to get parallel faces for holding in the mill. My plan is to get each end to length once the steam chest is made, and reference everything off that.



So I set the cylinder up in the mill. I used a height gauge to get each side of the steam chest area level before starting to clean up, then took the top close to the valve gland boss.



Then I started cleaning up the inside of the steam chest.



Now that I have straight edges, I can locate those accurately, and mill the sides and bottom of the chest to depth. Then I'll move on to the port slots.

Fairly happy with how things are going at this point.