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Hi Rich. Cracked it. Done a bit of digging and found out that there were several arrangements of the crosshead assembly, as Stephenson made various modifications and improvements. So, here is the version that Glithero photographed on the NRM original. From that I have produced a version that I...

Ah, but … the free plans are very low resolution and if you look, they are barely legible; certainly no use for modelling from. So, I’m afraid there is no choice but to pay for them. See the snippets I have shown in earlier posts. I have been talking with a very helpful young man (he/him) at the...

Thanks Rich. I was also thinking about making it in two parts. Machine the grooves and profile first an the solder on a boss. I don’t really see what that big vertical hole is for. There should be a slot for the Conrod and a hole for the piston rod in line with the grooves. Anyway, I am on...

Yes, it’s the crosshead that is puzzling me. If you look closely there is a hole with a label for a pump plunger. I am thinking of tilting the head of my mill at 45deg to cut the grooves and then machining the guide rails to fit. I was wondering about screwing the upper and lower parts to a...

Hi Rich. Here are the drawings. I know what it is supposed to achieve, but it's very hard to interpret how it looks. And what on earth is the pump plunger ?!? Bob

Another major milestone reached today. Got the whole valve mechanism built. Very fiddly and I spent ages getting all the links working correctly. Had to remake a few parts because they were a sloppy fit. When you look at the number of moving parts, you can see that all the clearances stack up...

Hello Samet. That's a very interesting question. I am using the plans from Julius de Waal which are not fully complete, and he says it is designed to be built in wood! He has omitted the valve gear, so I obtained further drawings from the National Rail Museum, here in York. This is a very...

Having finally got my head round the drawings, started on building the bits. Here are the eccentrics complete with reversing mechanism. Also the shafts and linkages for the lower half of the assembly. I have tried to follow the design as near as possible. However the drawings show some very...

Finally sussed out how it all works. Like all good engineering the beauty is the elegance and simplicity (once you get your head round the drawings!). Here's my current understanding: The eccentrics are mounted 90 degrees apart on the sliding sleeve. The left eccentric drives the left cylinder...

Still trying to work out how the levers work. On all the videos I have seen both of the valve levers are cycling up and down. So there must be a way to drive the main shaft from only one of them. But I’m darned if I can figure out how?!? Bob

Hi Basil. You are indeed correct, insofar as the shaft is made from two pieces. It appears to me however that they are keyed together. There has to be some means to only allow one gab rod at a time to drive the left and right crank levers. This why I think that one of the gabs has to be...

Splashed out and bought the drawing from the NRM which covered the valve gear and eccentrics. The detail was perfect and legible. After much head scratching and reading Bailey and Glithero's book, I finally manged to work out how it all was put together. I wanted to animate the assembly in Solid...

Got the cylinders made and associated bits to mount them on the boiler. The cylinders were made with the protrusion for the valve chest (not sure of the right name) all in one piece. The semi-circular part was done on the rotary table which was turned through a couple of degrees after each pass...

Hi Rich. Yes I should have said "available free", as I under stand it. I have actually bitten the bullet and ordered the sheet with the eccentrics and valve details. That was the part of the design I had difficulty following from Glithero's book. And yes I do have the Haynes manual as well. I...

Hi Rich. I have seen those drawings. Unfortunately the price has gone up to £240 for the set, which is a bit above my price range. They did say they are in the process of uploading all their drawings, and they should be freely available within 2 years ! Bob

Got the rear springs made. Very fiddly cos there are 18 pieces in each side. But this is what it looked like when assembled Now I’m going to start on the cylinders and valve gear. The more I get into this project the more I worry about its complexities. I think I have sorted the valve...

Thanks Ken. One of the points that I am unclear about is the size of the ports and their separation. Presumably it is a function of the bore and stroke. Bob

Thanks Greentwin. That gives me plenty of food for thought Bob

I have to take a short break from my workshop, so I am using the time to consider and draw the details which Julian has omitted from his "looking at" model of Stephenson's Rocket. The biggest challenge is the valve gear, He gives no information about the eccentrics, the port sizes and throw of...

Thanks K2 and Terry. I found Bailey and Glithero's book has the best info and will try to work from that. Bob