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Discussion Starter · #1 ·
As this is my first Aster kit, I may have a few questions about assembly. First, I have a question about the lapping of the bottom of the slide valves and the steam port plates in the cylinder assembly. Why are these the only components that need to be lapped? It would seem that all of the components in the assembly would need to be lapped to ensure no steam leakage.
 

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Ron,

The valves and port plates have to be lapped as they are in constant motion (moving connection) the lapping is to help the valves seat quickly so as to eliminate steam blowby. The rest of the steam fittings are either sealed with compound and therefore are static connections when compared to the slide valves. The pistons and the cylinders are bore matched and honed already so that portion is done for you from the factory.

Enjoy your kit and any questions just ask. Don't forget to take pictures and read the instructions/look at the diagrams numerous times.
 

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I don't know specifically about the S2, but the pistons probably have rings for seals. The bottom of the "D" valve needs lapped and I would expect the upper surface of the valve (or top of the cylinder casting). That is the only sliding "metal to metal" seal on the engine and thus the only parts that need to be lapped.
 

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The locomotive is propelled when the valve blocks move across the valve. Lapping of the valve surfaces ensures that the mating surfaces are flat and smooth so there is no leakage of steam as these parts slide past one another and providing the timed steam events of allowing steam to enter and for it to exhaust.
Lapping is pretty easy, given the proper wet sand paper. I believe the paper provided in the kit is 1000 grit. I have 1500 and 2000 grit wet dry for automotive body detailing. While the 1000 grit will work well, when I built my Mikado, I started with the 1000 grit and then went to the 1500 and finally to the 2000 grit. The valve faces turned out to gleam like mirrors. I did mine on the kitchen counter next to the sink. Make sure the surface that you do your lapping is dead flat. Place the paper grit side up, and wet it down with plenty of water. Gently push the part over the wet surface back and forth in a straight line motion. Inspect the surface and you'll see the milling maching lines fine as they are, begin to disappear. Keep adding water to the paper and continue lapping until these lines are completely gone and the surface takes on a shine like a mirror.

After each face of the mating faces are lapped, test them by moistening one of the lapped faces with water and gently placing it against the other lapped mating face. If the surfaces are properly lapped, they will draw together like a magnet and will seem to stick together. Dry each part and wrap it up and protect them until they are required for assembly.
 

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Not to bring up the old adage again, but anything more than 1000 grit paper is, well, frankly overkill. As I have either re-built or built countless numbers of valve chests, I can say that 1000 grit wet-dry paper is plenty for valve surfaces, unless there are severe milling errors. The valve blocks will settle into their own lap eventually as this is part of the seating process (thank gravity for that one, it pulls down on the valves causing them to create their own steam sealing).

Also, lapping back and forth is normally not recommended due to the stop start stroke that occurs, either a circular motion or 90* rotations after picking up the piece for another stroke is the preferred way.

And yes, the S-2 has rulon compression ring lands for the pistons to seal against the pistons, and like I said previously, the bores are already honed for you.
 

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I have used 1000 grit wet sandpaper as supplied in the Aster kit and have had no problems after building 5 Aster kits. A "figure 8" motion on the sandpaper works best for me and it is the one suggested by Aster. 1000 grit will give you a "dull" mirror finish. You can't see your reflection, but you can see individual light sources in it.
Make sure you read the S2 instructions very carefully and look at the assembly pictures closely. There are quite a few parts that look identical, but must be assembled in a certain way so you can later get at the screws without disassembling too much. The S2 seems to require more fitting/filing than previous Aster kits. Probably the factory trying to save $$ or using a different vendor for subassemblies.
 

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Discussion Starter · #7 ·
Question on cylinder assembly. It appears that the die block does not sit firmly within the slide valve due to the valve spindle passing through the die block, which slightly raises the die block off of the slide valve. This being the case it would seem that the slide valve, under steam pressure, would not seat properly against the steam port face and rise up to meet the bottom of the die block. Is this normal? I have a close-up picture and will post as soon as I figure out how to ddd photos. Any feedback is much appreciated.
 

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Steam pressure holds the D valve down against the seat. It can lift if the pressure in the cylinder become greater than the steam pressure and this is a good thing as this allows water in the cylinder to be expelled back into the steam side. This prevents problems with bent rods or (in the real world) cyclinder heads blown off.
 

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There are two things that will help make sure that the valves remain seated properly. First make sure that each die block and valve pair does not have any burrs that could cause them to hang up on each other. If so, clean off the burrs but avoid taking too much material off cause you want to keep the fit as close as possible without binding. Next, when installing the valve chest etc, tip the die block so that the end away from the spindle rests lightly on the valve and then tighten the set screws. This will keep the valve from lifting when you invert the engine for lubricating, cleaning, etc. This way you should have reliable valve operation regardless of the temperature.

Ross Schlabach
 

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Discussion Starter · #10 ·
Thanks guys, that makes sense. As this is my first live steamer, I am relying on you guys with your extensive knowledge to keep me on track. So far the process has been thoroughly enjoyable and I have learned much.
 

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There ain't nuttin like putting your engine together and studying the parts to understand what they do and why. The questions show you are doing it right... ain't it grand! :) I get all giggleified when I finally figure out why some oddball part is shaped the way it is or why parts are connected the way they are.

Just a note, I was quite concerned when I got my Mike to assemble, I remembered how difficult it was to, and how lousy I was at, assembling plastic model cars and such when I was a kid. Then I read Mark Horivitz's review in GR of his assembling a Mike and his comment that he had to file a little on the holes for the screws that hold the smokebox on. I didn't have that particular problem but had some other part that was a bit too tight of a fit and I had to run a file along one edge to "clean" it up some. My second Mike had no 'fit' problems at all, but it was totally missing the threads it two different parts! OUCH! The first one took me 20 minutes of fiddling before I took a good look at why I could not get that bolt started!

BUT... don't go filing away on things until you know that it is a problem with the part and not a problem with how you have assembled things up to that point.

Make sure you have the correct part in hand and not some mirror image part, or the "long" one instead of the "short" one.

You might find it better to loosen other screws such that parts can "adjust" in position slightly and a part then fit without alteration.

If you think you have found a burr or "flashing" on some part, make sure it REALLY is a burr or flash that you are cleaning up! You might just cut off some important protrusion used for alignment.

When putting parts together that have threads, whether a bolt/nut or just two parts that screw together, make sure you have not started the cross threaded. If there is significant resistance to turning them, double check that they are the correct parts and are aligned properly. It could be a tight fit, but more likely there is something wrong, so just double check it before applying the 3-ft monkey wrench or 5-lb sledge hammer.
 

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Posted By Ron67 on 06/08/2008 8:28 PM
link (I hope) to the cylinder pic showing the slide valve and die block question above.
http://i276.photobucket.com/albums/kk31/Ron67FL/Aster GN/Aster-1.jpg




Yep, looks a lot like the Mike valve assembly. Steam will fill the cavity that you can see all around the sliding valve parts. The actual valve is free to float somewhat but gets pushed back and forth by that big slug of brass attached to the rod. The steam exerts a pressure against the back of the sliding valve to hold it down against the face it slides over.

It looks like you have it assembled correctly. Not too sure if you have that slug too tight against the valve part. You want it to touch, but not apply lots of pressure downward (let the steam do that). Of course, the rod is free to rotate some just due to slop at the other end where it attaches to the combination lever, getting it really tight would be difficult, but if it is, it will produce excess friction in the "motor" that the motion would have to overcome.

That slug should also be a slip fit between the upper protrusions of the valve part. You do not want it to be real loose in that fit or have any amount of slop. It needs to push the valve forward and backward without slapping into the valve nor have any way for the rod to move without the valve moving with it. It can screw-up the timing if it is too loose.
 

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Ok, this question is for you guys that have the RTR S2's or have observed Han's pre-production prototypes.

According to Ross Schlabach's review on the S2, the drivers on the S2 are comprised of "tires" made of iron, pressed onto a forged center section. He goes onto say that this was a cost savings measure as well as a performance enhancement as this assembly is supposed to slip less than previous Aster locomotive models the the Mikado that had the stainless steel rims pressed onto forged center section.

So, has anyone noticed any difference in the traction power of the S2, say compared to the Berkshire? How will these new iron rimmed drivers going to wear over time? I would imagine they may rust over time if left in a humid environment. What about strength? Iron, I believe is softer than steel, but then most of the layouts are made of either brass or aluminum railed tracks. This may be a mute point, as I was just bored here at the office waiting for a certain package to arrive. Hard to say if it would be possible to literally "run the wheels off" of this locomotive. Any thoughts?

Oh, another question, how is the integral whistle? I don't recall seeing any reviews or comments on the topic.
 

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Well one more question to add to the list. I was looking at Samhongsa's brass version of the S2 and noticed marker lights on the tender, high up, just behind the oil bunker. I have not seen these in the pictures of the Aster version. Is this an oversight or are we talking perhaps, different time periods?
 

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Rob, As per the Aster web site:" both models are built to "AS RETIRED" specs" and from the photos of the static display engines it looks like no marker lights on the tender is correct.

GNSteamer, Aster used Iron tires on their early engines I would not worry about wearing them out, I think you will wear out long before those drivers... As for rusting, they look to be painted so this should not be a problem, traction should be better, the weight of the S2 is the same as the Berkshire and I have not found the Berk. lacking in traction, unless someone has "oiled down the rails" So with iron tires the S2 should be able to pull a sizeable train!
 

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I don't think the word "Oversight" exists in Han's dictionary. Exhaustive research has gone into this project in conjunction with the Great Northern Historic Society. Of all of the locomotive's in the Great Northern roster, this prototype's unique welded tender certainly simplified the replication of details in the model's Vanderbilt tender.
 

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Discussion Starter · #18 ·
Making progress on Black #, slow, but progress none the less. I have finished through step number three and am finding that the drive linkage is binding. I can get a 180 degree rotation but that's it. I've doubled checked all the steps leading up to this point but somehow something is not right. Will have to try to work this out before proceeding to the next step.
 

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Ron,

Be sure to add a drop of oil to all of the running gear and axle boxes. This can cause binding due to excessive friction....I have seen perfectly square frames and running gear bind because the bearings were left dry.
 

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the drive linkage is binding. I can get a 180 degree rotation but that's it. I've doubled checked all the steps leading up to this point but somehow something is not right. Will have to try to work this out before proceeding to the next step.



Ron, make sure the chassis is perfectly straight and that everything is square. The chassis should be built on a perfectly flat surface to make sure everything is in alignment.


Go back over every step in the book and double check your work and make sure the left and right parts are installed properly.


Just some thoughts from my experience.
 
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