"Catherine", a USA "Sweet Pea" engine build

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Benjamin Maggi
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Location: Albany, NY

Re: "Catherine", a USA "Sweet Pea" engine build

Post by Benjamin Maggi » Fri Nov 08, 2019 9:02 am

As evidenced by the pictures, the crankpins hadn’t been secured to the wheels yet. However, it was time to start fitting the pieces of the valve gear together to see how it all worked. At this time it is all just dry fitting and there are still lots of variables that need to be accounted for but it is a start. So, the pieces were temporarily put together and clearances were checked. But, a critical piece still had to be made: the valve gear extension rods. These connect the slide valve stems to the vibrating levers which are on the crank pins. Everything is connected with forked ends and spindles and fitted pins, so it was a lot of easy work on the lathe and mill to make them all.

The forked ends were made from some ½” square CR1018 steel that I had on hand. Sad to say, but these are actually the third set that I had to make for the project. Where the fork attaches at the rear to the vibrating lever there is absolutely no clearance between the back of the fork and the front of the slides and the design of the pin which holds the fork together is that it slides in from the back and it retained with a nut or an e-clip on the front. The clip/nut prevents the pin from sliding backwards and fouling the slide, and the pin has a larger diameter (1/4”) through the back of the fork than the front (3/16”) so it can’t shift forward. A simple plan, but I messed up the first set by switching the diameters of the holes so that set was ruined. The second set was made because I purchased replacement steel that was not actually ½” square, and that threw dimensions off. (Lesson: measure the stock you are buying at the store!) I made sure to drill through the 3/16” hole before cutting the slot so that the hole would be nice and straight.
Roughing the fork ends.jpg
Roughing the fork ends.jpg (21.15 KiB) Viewed 3004 times
Then, the slots were cut on the mill which was a little bit scary for me as I used a small mill cutter so I took it nice and slow. Those who work in ¾” scale are probably used to this type of thing. Once that was done, the ends were rounded on the belt sander and the one half of the fork’s hole was opened up to ¼” and then reamed nice and true. Finally, a curved profile was added to the front of the fork which made it look a little bit more elegant. Even on a basic quarry engine, the builders took some pride in their work.

The other end of the rod went into a fork that was a bit more basic in design. It was milled the same way, though the hole through it was a constant ¼” diameter and there is plenty of clearance on both sides for a hub on the rear and an e-clip on the front to retain the pin. The pins I used throughout were steel clevis pins that I cut to length, turned down in diameter where necessary, and slotted with a tool made from a portion of an old hacksaw blade.
Forks with pins assembled.jpg
Forks with pins assembled.jpg (20.94 KiB) Viewed 3004 times
All the holes for the pins were reamed and the pins fit in nice and smooth with no slop. I was quite happy with the results.
"One cannot learn to swim without getting his feet wet." - Benjamin Maggi
- Building: 7.25" gauge "Sweet Pea" named "Catherine"

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Benjamin Maggi
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Re: "Catherine", a USA "Sweet Pea" engine build

Post by Benjamin Maggi » Fri Nov 08, 2019 9:17 am

The design calls for the valve gear extension rods to have an outward bend in the middle, allows the rod to clear the motion plate bracket. However, because we had shimmed out our cylinders it wasn’t clear exactly how much clearance we would need. But, after centering the wheel/axles in the frame I measured out the distance of the vibrating lever and valve spindle and it was just about ¼” of variation. So, the rods which are just ¼” diameter steel were roughly cut to length and then marked out for the location of the bend, which is over a distance of about 3”. Then, the rod was put in a press with some steel plate and shims and the press was allowed to do its magic. Actually, we did a test rod first to make sure everything would work and it did. The rods needs just a slight adjustment at one part and that was that.
Bending the rod in the press.jpg
Bending the rod in the press.jpg (14.65 KiB) Viewed 3001 times
One end of the rod, which connects to the valve spindle, then had the end piece welded on. It was important that this was square and also in line with the bends of the rod. My friend did the welding, and again it came out fine. The picture shows them before cleanup, but a wire brush and the belt sander made them shine like new.
Welded rod ends - before cleanup.jpg
Welded rod ends - before cleanup.jpg (18.9 KiB) Viewed 3001 times
We left the rods over-length right now and didn't weld up the forked assembly on the other end that connects to the vibrating lever, as there are still too many variables left in the valve gear to figure out. Until the suspension springs are in place, the proper orientation of the slide blocks is set, and the valve gear is timed, etc. We will need to make a dummy set of adjustable valve gear extension rods before it is all over, but that should be easy. Until then, I put everything I had together and wrapped tape around the pin joints so that I wouldn't have to constantly add/remove the e-clips that hold it all together.
Valve gear temporarily pinned together.jpg
Valve gear temporarily pinned together.jpg (33.1 KiB) Viewed 3001 times
"One cannot learn to swim without getting his feet wet." - Benjamin Maggi
- Building: 7.25" gauge "Sweet Pea" named "Catherine"

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Benjamin Maggi
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Location: Albany, NY

Re: "Catherine", a USA "Sweet Pea" engine build

Post by Benjamin Maggi » Fri Jan 17, 2020 8:39 am

As the valve gear progressed it became obvious that I would need to start working on the reversing lever / Johnson bar assembly. Otherwise, what would it all connect to? The reversing lever is set on a stand with two round bars at the top into which notches are cut for the lever to drop into. While I am sure it all could be machined pretty easy on the mill with a rotary table, Blackgates Engineering offers a set of laser cut parts for this assembly and I felt that it was worth going that route. Thankfully, I am at the point in my life where time is just as valuable, if not more valuable, then money. The laser cut parts were cut with really smooth edges, and all of the hole locations were laid out. Instead of dimpling the hole locations, they had them marked with a cross-hair symbol. This made them easier to see, but I think that it made it more difficult to center-punch the holes. In one case the punch wandered a little bit and it was difficult to shift it back. Perhaps it is just my inexperience.

To keep up upper curved portions separate enough to allow the lever to slide back and forth easily, I turned up a pair of brass spacers. Amazingly, for me at least, they came out exactly perfect in both width and diameter (which wasn’t all that important) and they matched.
Reversing Quadrant-2.JPG
The simple latch piece was cut with a hacksaw out of some regular steel and then I filed it to shape. I wish I had made it oversize in case it needs to be adjusted a little bit, but it only took about a half-hour to get it done so remaking it wouldn’t be a total loss. It sort of reminded me of what locomotive builders must have experienced seventy-five years ago when all they had was a hacksaw, drill, and a file.
Reversing Quadrant-8.JPG
My friend worked on the handle and latch lever assembly. We had the plans from Blackgates which showed the individual pieces but not a general assembly so it first required some thinking to figure out how everything worked together. I found some pictures online of 5” gauge Sweet Pea engines that utilize a similar mechanism but I am not sure if they are the exact same. He used a round mill cutter and files to really make the part and I think he did a fantastic job.
Reversing Quadrant-10.JPG
"One cannot learn to swim without getting his feet wet." - Benjamin Maggi
- Building: 7.25" gauge "Sweet Pea" named "Catherine"

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Benjamin Maggi
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Re: "Catherine", a USA "Sweet Pea" engine build

Post by Benjamin Maggi » Fri Jan 17, 2020 8:44 am

While he worked on that, I used a belt sander and some files to round over the reversing lever handle portion to a more pleasing and comfortable profile too. Then, I had to assemble what we had done so far to see how it looked.
Reversing Quadrant-14.JPG
Then, we moved on to the reversing stand support bracket. This fabrication has two purposes: the first is that it holds the bottom of the reversing lever in position in the cab near the floor, and the second is that it also supports a hand pump which is secured to the cross brace. The plans here were very confusing, being a general arrangement of seemingly random dimensions taken from difference pieces to different hole centers and edges. The overall dimensions of the pieces weren’t given but had to be calculated by a lot of “add this, subtract that, double it for both ends” etc. In the process I got one piece wrong and had to remake it but steel is pretty cheap. I used cold rolled, and much of the machining was done on the mill. The holes were drilled on the press.
Reversing Quadrant-20.JPG
Then, to support them for welding, small 1/8” diameter holes were drilled in the pieces and through to the edges of the cross brace. After cleaning the pieces with lacquer thinner, I pounded in small pieces of 1/8” rod which pinned the parts together. Another option would have been drilling and tapping them for screws, but this seemed a bit overkill. I know Kozo likes to do it, and had the parts threatened to shift a lot during welding I might have gone that route.
Reversing Quadrant-21.JPG
Then they were stick welded and the joints were cleaned up. The results aren’t as pretty as if they had been silver soldered but it is plenty strong.
"One cannot learn to swim without getting his feet wet." - Benjamin Maggi
- Building: 7.25" gauge "Sweet Pea" named "Catherine"

Harold_V
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Re: "Catherine", a USA "Sweet Pea" engine build

Post by Harold_V » Sat Jan 18, 2020 2:57 am

Benjamin Maggi wrote:
Fri Jan 17, 2020 8:39 am
Instead of dimpling the hole locations, they had them marked with a cross-hair symbol. This made them easier to see, but I think that it made it more difficult to center-punch the holes. In one case the punch wandered a little bit and it was difficult to shift it back. Perhaps it is just my inexperience.
You'd have been far better served to not punch. Using a wiggler, with the part in your vertical mill, picking up the cross hair and then starting the hole with a center drill or a spot drill would be so much better. My advice to you is to NEVER use a center punch to start a hole if it is critical. If you must drill by hand, yeah, use a center punch.

H
Wise people talk because they have something to say. Fools talk because they have to say something.

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Benjamin Maggi
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Re: "Catherine", a USA "Sweet Pea" engine build

Post by Benjamin Maggi » Sat Jan 18, 2020 9:15 pm

Harold, I must agree. Lesson learned.
"One cannot learn to swim without getting his feet wet." - Benjamin Maggi
- Building: 7.25" gauge "Sweet Pea" named "Catherine"

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Benjamin Maggi
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Re: "Catherine", a USA "Sweet Pea" engine build

Post by Benjamin Maggi » Tue Jan 21, 2020 4:50 pm

With the reversing lever coming along, I needed a spot to attach it to the chassis. The holes for the supporting bracket had been drilled in the frame years ago, and now they were finally getting used. The laser-cut reversing lever parts needed to be welded together, which was a pretty simple job. A few stray spots along the joint line were filed away until it fit together tightly- this time a good thing as it would help hold it in the perfect 90-degree alignment during welding.
IMG_1125.JPG
When I tried to attach the reversing lever assembly to the bracket I noticed that the four bolt mounting holes didn’t match up with the bracket. I measured the holes I had laid out on the bracket base and they were to the prints. Then I measured the holes that had been laid out on the laser-cut reversing lever stand base and discovered they were off by 1/16”! Consulting the prints again, I discovered an error in the parts (the top of the bracket calls for one dimension, the base of the reversing lever calls for another). It wasn’t a critical problem, but had I spotted it before drilling the holes it could have easily been corrected. Doh! So, I clamped the pieces together and then redrilled the holes which resulted in some ugly, egg-shaped hole. The optimist would say that the parts now have a slight amount of adjustability which may prove useful when setting up the valve gear.
IMG_1128.JPG
I also installed the axlebox suspension springs to the chassis. The original prints called for turning “bowl” shaped assemblies which would secure the springs in place. Instead, we used socket head cap screws at the top and bottom to do the same thing. I removed the top screws, slipped in the springs (which were a tight fit) and replaced the screws. If I want to block up the axlebox I just need to use longer screws or screws them in more or less until they bottom out at the top of the axlebox.
Axlebox-15.JPG
Lastly, I corrected the protruding heads of the screws from the slides which were interfering with the rotation of the vibrating levers. I had countersunk the screw heads but not enough, and even just a little bit was a problem. The picture below shows the work in progress, but some still need to go lower. Looking back now, if I had made the covers wider (there is no reason they couldn’t be wider) then the holes wouldn’t be so close to the edges. If they prove to be a problem I might go back and remake them sometime.
Slides-14.JPG
"One cannot learn to swim without getting his feet wet." - Benjamin Maggi
- Building: 7.25" gauge "Sweet Pea" named "Catherine"

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JohnR
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Re: "Catherine", a USA "Sweet Pea" engine build

Post by JohnR » Sat May 23, 2020 11:14 am

Ben
I have been following your series and have wondered where you are at.
I am finishing up my Sweet William and am waiting a boiler test so that I can get it out
on the track (legally).
I do not want to jeopardize the inspection crew with the covid problem .
We will not be open to the public until June possibly so there is no hurry.

John R.

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Benjamin Maggi
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Re: "Catherine", a USA "Sweet Pea" engine build

Post by Benjamin Maggi » Sat May 23, 2020 1:42 pm

I am still working on the valve gear. We ran into a snag in that it seems one of the dimensions on the plans is not correct... the connecting rods appear to be 1" too long. And, it took us a bit to come to that conclusion. If you don't mind me asking, could you tell me the distance between centers of your connecting rods from center of crank pin to center of crosshead pin? And were your piston rods extra-long too?

Thanks.
"One cannot learn to swim without getting his feet wet." - Benjamin Maggi
- Building: 7.25" gauge "Sweet Pea" named "Catherine"

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JohnR
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Re: "Catherine", a USA "Sweet Pea" engine build

Post by JohnR » Sun May 24, 2020 5:02 pm

Ben
When I get back to work on Tuesday I will pull up the information and post it.
John R

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Benjamin Maggi
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Re: "Catherine", a USA "Sweet Pea" engine build

Post by Benjamin Maggi » Sun May 24, 2020 8:01 pm

Thanks!
"One cannot learn to swim without getting his feet wet." - Benjamin Maggi
- Building: 7.25" gauge "Sweet Pea" named "Catherine"

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JohnR
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Re: "Catherine", a USA "Sweet Pea" engine build

Post by JohnR » Thu May 28, 2020 11:34 am

Benjamin

Sorry about the delay on getting the dimensions on my Sweet William.
The connecting rods are 13.3125" center to center.
The driver rod (cylinder slide to fulcrum or wrist Pin) 12.9375"
Hope this helps you.
Hopefully if the weather permits I will be getting my engine out on the
track this weekend.
Running the engine on the test stand is getting old.

John

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