Stuart Twin Victoria from scratch

[Mechanicboy]

Hi, the fit is too sloppy.

It must be slack free fit (zero play) to keep timing correct but move free in sideways created by pressure of steam. Keep milling pin sharp when milling in bronce + low feeding then all surfaces will be better and true.

 

[Jack3M]

Thanks, I wondered about that.

 

[Jack3M]

In remaking the slide valves again yesterday, it was discovered it was the nut, not the slot that was incorrect size. But I felt the old ones were shoddy workmanship and redid them with a sharp bit.

 

[Mechanicboy]

First of all: Milling the inside room for exhaust in correct size, then trim the outer side around the valve with correct width. See picture..

Second: Hold the valve on milling table or in precision vice and create grove for valve rod and nut for rod.

 

[Jack3M]

The new and improved, no slop at all.

 

[Jack3M]

Got another piece done. This one was a 'screwed' up casting, but the other one, which is right, isn't the right diameter inside so I need to make another with a smaller hole. LOL.

 

[Jack3M]

Was just reflecting on some of the things I have learned so far with this project. First, the reason I could not figure out the cylinders was because some items are cast in but not shown in the plans. Glad I bought the cylinders, and could have used the ones I cast in bronze. It was very difficult to get the casting sand out from the passages.

When casting raw parts, you can have multiple failures in the edges so long as it is to the positive side (or the side that needs to be cleaned up) of the part. This includes casting your own bar stock, which is much more cost effective than buying bar stock in bronze...at least for me.

8BA converts well to 2.0 mm
7BA converts well to 2.5 mm
5 BA converts well to 3.0 mm

Probably doing many things the 'wrong' way. That is the advantage to not knowing what you are doing. Having fun, regardless of right or wrong.

 

[Runner]

8BA converts well to 2.0 mm
7BA converts well to 2.5 mm
5 BA converts well to 3.0 mm


I found this also to be the case when I changed all my hex headed BA steel fasteners with stainless hex drive screws on my locomotives. 3.0 mm hex drive screws replaced 6 BA fasteners, it was probably more like the stainless being hard enough to cut a new thread into the brass or gunmetal female thread. Hex drive stainless steel by virtue of the use of an allen key can be nipped up much tighter without fear of shearing off the screw as was the case when just using steel screws.

Brian

 

[Jack3M]

Cyl brackets, two are cast bronze, two are bar stock alum.

Cleaning up the second eccentric strap and machining.



Boring to size after cutting and bolting together.



Done


Done is relative, got holes to drill and such still, polish, etc.

 

[Jack3M]

Got both bearing stands made and a pair of oil cups. Tried in the crankshaft and smooth silky fit.

Still need to paint them among other things

 

[Jack3M]

Painted bearings, and the slides for the crossheads. Those were kind of fun to make. Spent more time thinking on process than doing.

 

[Jack3M]

LOL, getting pics from phone to computer and deleted half of the ones I wanted to post, got to take them again not. LOL....COFFEE. More coffee.



Cranks



Not sure what to call this but it was not easy to make. Albeit it seems/looks easy. It has different hole sizes on the same plane and it is difficult to keep them both on the same plane, drill bits wander a bit over that full depth, but they work and the holes are for an axle that will never move, so a tight fit is good.



The top rail for the crosshead slides. Bottom is just straight forward with comparable holes for mounting. With oil cup.

 

[Jack3M]

Shuckey darns, I need to remake both of these, going to use bronze now. It is actually a bearing surface for the shaft that connects to the eccentric and the steam chest shaft.

So started by whacking off a hunk of bronze from the ingot, no need to melt this time....I think I waste more in the melt.

 

[Jack3M]

Okay, been crazy this week. Bees are swarming. Caught and lost one bunch. Hot for here 90 yesterday, real killer after last week in the 50's.

The only lathe work left is the eccentrics and the connecting rods, which have a double taper, one on each end. All 4-jaw work, which I have learned not to freak about. Quite concerned about how to go about this one part tho. Been thinking on it for awhile. Since it is unequal sides with the double taper between the ends I am thinking get the taper first with 4 jaw and live center, then mill in the two ends.


Regardless been doing little bits and pieces along with redoing the whatever it is called. I prefer do-hickey, but it could be a doo-hickey whompus. Whatever.



Then these, fiddly little bits and glands. Why two glands in bronze and two in brass? Well that was what I had, will pair them accordingly on the assembly

 

[Jack3M]

Kept having probs with pictures. Lost the ones of the eccentrics. But still have 2 of the con rod.

The con rod was a big worry as mentioned above. The double taper was a challenge for me, goofed a little on one, but sort of make it look right. Did not want to have to re-cast a hunk of metal after all this turning. Lots of waste.

Regardless a pair of pieces were cast that were 10" long, and 1/2x34, milling that down to true 3/8x1/2. Rounded the center to largest diameter and then tapered from center to each end. My cross slide isn't marked in single degree increments so I had to guess and that is how the first one got a bit off...

Then the ends were drilled and milled to proper sizes. There will be a bushing in the one end, which still needs made.

So now with these done, just need to do the cylinders that I bought, and find some 1/4x1/8 steel, which is proving to be a challenge here locally.

Pictures.

 

[Jack3M]

Eccentric sheaves, in place with the specific eccentric as each one is slightly different and for smooth operation they needed to be fitted to each separately.



The cylinders bored and sized. Note the port INSIDE the cylinder. They really make nice stuff, Stuart does. Wish I could cast that well.



And slightly exciting, the assembly begins. This is the bushing pressed in place with the bolt



Now the base size will have to be figured out and on preliminary inspection, it will be necessary to do a partial mockup with the cylinders and rods and such. Plus I want to make a governor and install that. Need to look at those plans now too, maybe I should make those parts as well first? Pause time me thinks, to figure this out. Put a lot of work in so far and don't want to screw up now. Other than decent plywood, I cannot think of a good material for the base. I do have thin sheets of exotic woods that I can use to cover it with, but the top of the base will look odd in wood. Considering some diamond plate that is made for models. It is aluminum, but could be darkened with stain. I am wide open to suggestions on that folks. It may look really cool with a railing around the perimeter, made from brass.

 

[Jack3M]

So to do the mockup to get measurements and ideas about the base, it was necessary to make the governor drive sheave. Popped that out in a few minutes


Then put everything in place and got the general idea of how things fit together, made sure midlines were correct to visual. This piece of Paduk has been on the shelf for years since I quit making guitars. Reluctantly I made sawdust. (my allergies are nuts now).

Though not shown it is doweled and glued together and clamped. Tomorrow it can go thru the drum sander. Kind of exciting photos. This encompassed hours of miniscule adjustments. In looking at the plans for the governor, I think I will make a different mount in the middle between the two halves.

Might be too busy to play tomorrow, so probably nothing. Looks like a beekeeping day.



In looking at this I see I neglected to take the photos of the pieces of wood that was glued between. Maybe after sanding.

 

[Jack3M]

Big day, got lots done, everything went well and fast it seems. Yesterday was sand the base and varnish it. Today parts started getting fastened down.

The two bases were installed with Black countersunk wood phillips head screws. No if you remember I said one of the bases had a flaw, one of the mounting tabs. So under the crankshaft bearing a hole was drilled thru the entire base and another of the screws installed. It was slightly proud and had to modify it a touch to assure clearance. As it was, that side took shims to bring the bearing base/tower to equal heights to prevent binding on the crankshaft itself as the towers were tightened down. Towers were installed on 4 mm studs that were made and locktited in. The shimming process took me several hours to figure out, but once it was there, it is like glass. Photos regarding this portion.

 

[Jack3M]

Then this afternoon, many set screw holes were drilled and threaded, these included the Cranks to Crankshaft (Only I bolted them clear thru the shaft) and eccentrics. Got to thinking I should do up the shafts for the eccentrics while we were at this point, this was the metal I had trouble sourcing, 3/16x1/4. McMaster Carr killed me on the shipping, such is life. The bolts I used for that were 2.5 mm if anyone is interested. (I have had metric tools from way back, hardly own any imperial stuff, so metric it is.

Wasn't sure if the cranks should be 180 apart or the same. Photos I have seen have them most of the time haphazardly, so the idea of balance seemed appropriate in this case so 180 it is. Then assembled all that on the crankshaft, lined things up and lightly tightened them down so as to not score the crankshaft too badly at this point. Not sure if I can upload video here or need to upload somewhere else and link it so will do a different post for that. But, with all the weight and piston rods and eccentrics dragging it still turns smoothly without a lot of effort, and it isn't lubed yet.

 

[Jack3M]

The link to motion.
[ame]https://www.youtube.com/watch?v=Cpw1k5mXqcE&feature=youtu.be[/ame]