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Asterís NKP Berkshire #779

an assembly review by Howard Freed

with photos by Jason Musheno


I first set eyes on Asterís NKP Berkshire #779 in Diamondhead, Mississippi at the 2005 International Steamup. The beauty of this engine made it irresistible, and I put my deposit down for a kit on the spot. I have been looking forward to building it ever since.

This engine has several features that I was particularly interested in discovering how they worked. Building these locomotives, have been one of the best learning projects I've ever experienced. The following is my report on the assembly, and how I went about building this beautiful locomotive.

One of the first surprises I found with this kit is that Aster changed the format of the assembly manual. Instead of having two manuals for assembly there is only one; and instead of using the exploded drawings they used photographs complete with assembly notes all in one. This will be a new experience, as I have grown used to the old way of building Aster locomotives. 

Pilot Truck  

In the past Aster has given a sequence for assembly they recommend following, but I have several times put most of the assembly together, only to get to the last part, and find they should have had you install this part much earlier. I've had to disassemble the work just to get this part installed, and then reassemble everything.



I found this to be true with the very first assembly step which is the pilot wheel. Part # A3 the pilot truck stretcher, needs to be installed before the # A1 journal box frame, then install #A1 running the screw driver through the triangular hole in the pilot truck frame #A2 to tighten the pan head screw. When you are ready to install the wheels on the pilot truck assembly give the journal box holder #A9 threaded rod, a trial fit before you install the journal box. The holes for the rod were not lined up on my kit, and I had to file, ream, and re tap to get it to fit. If you scratch the paint on this I found a black Magic Marker covers it quite well.  

Trailing Truck 

This is pretty straight forward, and only needed a little filing on the journal boxes for a smooth fit. Upon completion of this impressive piece you will notice what a heavy duty work horse, you are building. 


Main Frame 

The next step is the building of the main frame. It is advised that you assemble this on a piece of heavy glass. You will want to take your time with this, because it is critical to build it perfectly straight. The slightest warp will cause unbelievable binding problems later, so be sure it sits square on the glass, without any rocking. Itís amazing to think the full size frames were cast in one pour, and that usually included the cylinders!  


After the main frame is built the suspension system is installed. The equalizer fulcrum # C25 is a very tight fit into the guide #C26 and C27. I found that it snapped into place with a little tap from a small mallet. Once you have the whole suspension assembly in place, oil all the joints, and be sure to add oil between the triangular pieces and the frame. These pieces slide back and forth, and will rub against the frame.  

Once the wheels and brakes are added you can see what a gem this locomotive is going to be. 


Axle Driven Pump 

The next two steps are the assembly of the water pump which is a new sleek design. This has a hinged joint in the push rod that bends slightly when running, so be sure to line the hinge vertically to keep the O-ring properly centered. The step following this is the linkage for the cylinder cocks, or drains.  



The cylinders are the next assembly. Once again Aster has come up with a better design. The top of the cylinder, which when assembled is the floor of the steam chest, is now a separate part. This makes lapping much easier, because instead of lapping the whole cylinder, which can be awkward, and take the true square off the cylinder top, you now have a flat plate, which is lapped separately, then installed with a gasket. 


A word of caution: the steam ports, and the milled out valleys, are very small, so the amount of silicon that is applied to the gasket should be very thin, so as not to block the ports. 

The valves for the cylinder cocks are installed before the lapped plate, and the steam chest. Then the steam chest is installed to the top of the whole cylinder assembly, with another gasket. Pay attention to the tapered bolt holes, and the opening for the piston rod in the steam chest. It is not very noticeable in the manual, but these can be over looked, and if installed incorrectly the top of the steam chest will not close.  

When assembled, the top of the steam chest complete with tapered screws should be flush, so the roof of the steam chest will seal tight, when screwed into place. One other point to take note of is part #F8. This is the valve for the cylinder cocks. As noted in the manual both pieces are mounted with the extended finger on the right side. This is so the left side, which is folded down into the groove first, then the right side is folded down, and will cradle into the recess created by the left side. This way, as the cam, part #E16 & E17 is turned, it will push down on these two arms, and open the cylinder cocks.


The cross heads and linkage will take a little time to assemble, but following the book shouldn't be much of a problem. The steam chest cover on my locomotive needed to have the holes drilled out. The screws would not fit.  First I tried to ream them out, but the material is too hard, even filing didn't work very well so I used a #44 bit, and drilled the holes out. This worked very well.  

Another part of the cylinder assembly which I found to be a challenge is the linkage arm that extends down from the lubricator just behind the cylinder, and directly over the cross head guide. Aster supplied a roll pin to connect the leakage together. I found this to be impossible, and almost broke the tiny arm trying to get the roll pin in. Instead, I got a dressmakers straight pin, cut half the pin off, then bent the pin first, then slipped it through the hole. Cutting off all that wasn't needed of the pin; I bent it around toward the front only bending the pin against itself. Don't try to bend the pin against the linkage because it isn't strong enough. The finished product looked much better than the roll pin.  

There are a few more pieces to assemble on the cylinder assembly to complete it. The next part is the Baker valve gear. This is very straight forward in the assembly, and a very interesting part to watch work, once it is finished.  


The mounting of the cylinders and valve gear are the next step, and should be done carefully to insure all parts move freely when done. Follow the manual it covers all the necessary advice needed, including loosening some of the screws so the parts can be checked for ease of movement when re tightened.  

When all this is completed the linkage for all the wheels are installed. This is very exciting because you now have half the locomotive built.


Valve Setting 

The valve setting is slightly different on the Berkshire from earlier Aster Locomotives. Before, you needed to work with the angle of the eccentric crank. A piece of card stock, cut to the proper angle, was the best way to set this. The new way is to measure from the axle centerline to the center line of the eccentric pin. This is much easier to accurately set the eccentric crank.  

Once all this is done the air test is run. If all works well, you should go back and tighten all the screws, as well as using the silicon sealant to seal off the top of the steam chest. Then install the covers on the steam chest and the base for the smoke box.  

The air test will give you a feel for what a great runner this locomotive is going to be. Once you have run it, sit back and admire your work.  


To finish the cylinders several things were missed in the instruction manual. Sealing the top of the steam chest is the first. The gaskets, that up to now have been installed dry, should be removed and covered with a fine layer of silicon to completely seal the steam chest off. The imprint of the top wall of the steam chest should be impressed on the gasket and I would recommend only applying silicon to the perimeter. You want to avoid any excess silicon getting into the slide valve. The next is reinstalling the gear frame part #G16 & G17 to the front of the Baker Valve Gear, before you install the outside covers of the cylinders. 

The Boiler 

The firebox is straight forward with one exception. I believe Aster is buying the ceramic sheets from another vender. In the past I would cut the sheet to fit the application, then apply silicon to the sheet and install it in place. This ceramic sheet has a coating on it which prevents anything from adhering to it. I applied silicon to the part I was lining instead, and then applied the ceramic sheet to it. For some reason this worked fine, and within an hour the silicon had dried and the ceramic sheet was firmly attached.  


Now for the boiler.  Aster has come up with a new design for the sight glass. I found it takes a bit of fiddling with the brass ends to get them to fit into the steel mounting bracket. If you keep working with it, it will go together without filing or re tapping. Installing the O-rings to the sight glass is always a challenge. I find using the backside of a dentist pick with a close curve toward the end, (not the sharp side) is helpful in pushing the O-ring into the brass sealing ring.  


The back head is assembled which only needs a few comments. Be sure to install the whistle with the opening facing down, so any water that accumulates from the use of the whistle will empty out. The control stem is a very impressive unit that goes together without any problem. Itís a very sleek design, and compliments the cab of the locomotive.  


Installing the piping uses two different banjo bolts. One type has a large opening, and is used for the sight glass. The bolts with the smaller openings are used for everything else. This is a very nice assembly because all of the piping is preformed, and fits very well.  

The burner wicks are cut and placed, and the unit is then put away for later installation.  


Air testing the boiler may be easier to do if you inject the air into the check valve rather than the drain valve as indicated in the manual. It will depend on the air fittings you have on hand.  

Boiler Casing and Fittings 

Putting all the fittings on the boiler casing is like a double edge sword. Itís exciting to see the locomotive forming as you add the fittings, but you must be so careful, because your work here is what really shows. One scratch or broken part, and everyone that looks at it may see it! Keep in mind your best friend here may be the black permanent magic marker.


I found all the parts fit very well until I started installing the sand pipes to the sand dome. Aster has revised the way the sand pipes fit, and I found the new method to be exceptional. I did find, however, when they painted the sand dome, the paint ran into the holes where the sand pipes fit into the sand dome. These needed to be drilled out again. I also drilled them a little deeper than they were originally, just to allow for more working space. If you do this you, will need a #61 drill bit, and I must warn you to be very careful because breaking a drill bit inside of a hole that small, can be impossible to remove.  

Once the holes were drilled I pre-formed the sand pipes using my fingers to conform to the curvature of the boiler case. After I had all the pipes roughly curved, I worked with the boiler case upside down, first fitting the pipe into the elongated slots, then into the sand dome. The pipes fit without any trouble. Then using a toothpick I applied a tiny amount of super glue to the joint where the pipes run into the sand dome, just to insure they stayed in place. 

Running Boards  

Bending the wire for the pipes that run under the running board was not difficult. Spend all the time it takes to do it carefully. I used the handle of an Exacto knife which measured 8 mm to do the bending.  

Smoke Box 

The smoke box has a few fittings installed. Then you add two layers of ceramic sheet insulation. The important thing here is to remember to leave space for the smoke box front to fit tightly up against the insulation. I also found if you use too much silicon on the inside of the smoke box it will exude out through some of the holes where the fittings have already been installed. Use caution around all the holes in the smoke box.  Clean off any silicone that exudes through the holes immediately.  


The smoke box door is installed using the roll pins for hinges. Once again I found these to be absolutely impossible. I did manage to press one in on the top hinge, but before I could get anywhere with the lower pin it shot out of the tweezers and was lost. As in the earlier case I used a dress makerís pin with a head on it, and it worked, and looked perfect. This smoke box is a very impressive addition, with all the headlights, number boards, and fittings.  

The Cab 

Assembling the cab always feels like a reward, because now you can see what all the parts of the locomotive look like. The fittings for the cab go together without much trouble. The tabs on the wing window frames must be bent out so you can install the frame to the cab. Then the tabs need to be bent back and the wing window glued in place. Care must be given to get the right mounting piece on the right hand rail for the rear of the cab. The little tabs are bent together to hold the hand rail in place. Once these are installed you want to be careful about placing the cab down so you don't bend the handrails.  


The floor assembly should go together without a problem. One thing that is not very clear on the instruction manual is where the washer #M24 is supposed to go. This is installed under the floor with a M2 2.5 screw to the bottom of the reverser handle, to keep it in place.


Front Coupler Beam  

The front coupler beam is a beautifully designed piece. Once assembled the knuckle coupler works just like the real one. When installing the connecting wire for the lifting pin in the coupler, the wire must be slightly straightened so the wire will run through the hole in the lifting pin. Just straighten it enough to get it through the hole then bend it back to its original shape. 


The ladders must be mounted with the threaded hole on the top of the ladder.  This will later screw the ladder to running board. 

Front Deck  

The last assembly for the locomotive is the front deck. I found the only difficulty with this was the compressor jacket and holder, parts#02/04 and #03/05. Looking at the picture in the manual its difficult to see which way is up or down. If you assemble them so the compressors (one per side) is mounted on the bottom, and the top is open, you will have it assembled correctly. The deck step, part #011 is temporarily mounted and will need to be taken off later to mount the whole front deck assembly to the frame.  

Now that you have assembled all the component parts for the locomotive, and are anxious to see what it looks like assembled, Aster has you put all these parts to the side and start building the tender. I assume they figured, since youíre in the building mode, you should stay there and keep building.  

The Tender  

The tender is started with the assembly of the Buckeye trucks. I found these fascinating in design. They are built to run on very uneven track and keep a tight grip with wheels firmly on the track no matter how much the rails rock and roll. The manual is very straight forward, and easy to read here. A little time should be taken to pre-bend a ninety degree angle in the wire for the journal box doors, slip it into the hinge on the door, bend another ninety degree bend, and cut the wire off on both ends to make it a neat job.  


Once all the doors are mounted the next step is to add the wheels to the truck, run a screw through a washer into the axle inside of the journal box just like the real one. The rest of the assembly is clearly outlined until you get to the very end. The #P20 x 2 washers are set aside until the trucks are mounted to the chassis.  

When the tender floor is assembled please note there are two different sets of ladders (two each). One set is angled to one side and the other set is straight. The angled set is the one that is mounted in the front. The knuckle couple is assembled the same as was just done for the locomotive.  

The draw bar locking release is assembled, and the manual calls for a #M2 black nut to be placed on the bottom of the handle. This is the wrong nut it should be a #M2.6 silver nut.  

The sump is mounted with spacers placed on top of the floor so the sump sits half way above the floor level and half way below the floor level. This is a different design than past models have used. The truck mounting brackets and a few detail fittings are added to complete the floor assembly.  


The tender body is clearly outlined with one detail that may be in question. The rail that goes around the top of the tender deck is all pre formed. Rail #R4 runs down the left side, and #R6 runs down the right side (this rail has a ninety degree bend in it). First thread the rail though all the stanchions on the right side. Then the small bend on #R6 is bent out so it makes the corner and runs about half way into the rail stanchion on the rear end of the deck. #R5 is a small straight piece that runs across the back and the end slips into the other half of the same rail stanchion, making it look like the whole rail is one piece.  

The tender water pump is assembled, and mounted next. The only thing to note on the pump is the #R20 cover has a hole in it, and it is mounted facing the bottom of the pump. I would recommend applying silicon to the treads of #R19 & R20. Be sure to check to hear the steel ball rattle when the covers are tightened.  If silicon gets on the steel ball the pump won't work. When mounting the pump be sure to apply silicon to the bottom of the pump, so the mounting screws are sealed in. One other place to silicon in is both of the ends of the water tank. I have completely assembled tenders, taken the locomotive out to fire it up, and find the tender water tank leaks. Silicon all the joints and corners to make sure it is water tight.  Let the silicone cure overnight before testing. Another great addition to this tender is the water tank has a drain with a removable plug. To finish the water tank the two copper water pipes are connected to the water tank and it's ready to mount to the body.  

The flow regulator, and the filler cap are installed on the alcohol tank, and the rubber hoses are readied for installation. The alcohol tank is another new improvement Aster has incorporated into this model. The alcohol tank is a lift out tank, and can be taken out of the tender completely to fill or empty it. In an email with Hans Huwyler of AsterHobbyUSA, Hans told me the ample space underneath the alcohol tank is for radio control equipment. Once again the improvements on this locomotive are outstanding.  

After the body is assembled the hoses for water and alcohol are installed, and the trucks are put in place using the #P20 x2 washers, and M3 nut. Now sit back and enjoy looking at your new tender. Just its size is impressive. 


Locomotive Final Assembly 

The final assembly has been carefully thought out by the design engineers.  If you carefully follow the manual you should have no problem finishing your locomotive.  

Here  are a couple of suggestions that might save you some time.  

The first is the application of the ceramic sheet strips, used to seal off the space between the boiler, and its casing. On the last Aster locomotive I assembled (The Duchess of Sutherland) I was able to use silicon and adhere it right to the boiler.  Then using a piece of paper as a funnel I slipped it into place neat as a pin. This didn't work on the Berkshire, because there are too many obstacles in the way.  

I would recommend using the boiler as a template applying four or five layers of the ceramic sheet strips glued together with silicone around the boiler (do not apply silicon to the boiler as the strips should not be glued to the boiler yet). Start and stop the strips in the same place, so you have a seam that runs through all the layers. Let the silicon set for a half hour, then carefully slip them off the front of the boiler opening the seam as needed, but keeping the round shape.  

Next set the boiler into its casing, working from the front, placing the ceramic circle into the opening, as evenly as possible. You want the front to be straight and even. If you need to trim a little off, do it carefully. Once itís in place, you can now set the whole boiler on the chassis and connect the water pipe #D15 to the check valve #I 17. Following the manual secure the boiler to the chassis, first in the front with Nut #M3 and then Truss head screw #M3-5. Now that everything is secured, go back to the front of the boiler, and put a layer of silicon over the ceramic strips, forming a seal between the casing and the boiler.  

There should not be any air flow between the boiler and the casing into the smoke box. If you follow the instructions it should be clear how the smoke box is installed. One point to remember, when installing the smoke box be sure to run the wire on the right side of the boiler into the throttle lever on the right side of the smoke box. Once the smoke box is installed, you can now reinstall the blast pipe back in place.

Check the seal around the hole where the blast pipe comes up through the floor.  Also, check the slot in the back of the smoke box, where the super heater runs out of the smoke box, to insure an air tight seal. Remember a vacuum is created in the smoke box to create a draft for the heat from the burner to flow through the boiler tubes then into the smoke box, and out the smoke stack. Any air leak will seriously affect the performance of your locomotive.  

After the smoke box is in place the front deck is installed. The ladder and coupler assembly went on fine, but the compressor assembly needed to work around the dummy air hose to fit into place. I found if you tilt the back end up, and slid the assembly in from the back to the front; it will slide right under the dummy air hose. Next reinstall the smoke box door. If its too tight a fit, use a tiny round file making the opening slightly larger.  

The running boards and the detail parts attached to them, are installed next.  

The floor of the cab should fit in place neatly. If you have any trouble with the fit, check to make sure the water pipe that is now connected to the check valve is centered in the slot provided. Finally the cab is installed, and the hand rails in the back are secured in place.  

The linkage rod that runs from the reverser lever, to the linkage under the running board, is installed and should be tested, to make sure the set screw has been tightened in the right place. The reverser lever needs to move the Baker valve gear into its forward, and reverse position.  

The pilot wheels, and trailing trucks are the last installation, and need to be set using the #A 10 washers. Be sure to oil the connecting posts where the screws are placed.  

Now grab a beverage, aim a spot light on the locomotive, and tender, and enjoy looking at you new locomotive. 

Test run 

I ran my locomotive the first time, on a cold day so I could see the exhaust. I did a test run on Aster rollers. I like testing my locomotives on rollers, because I can monitor everything, and make sure all is well, during the break in period. 

Firing up the locomotive went well; with four burners you really get quite a fire under there. I used the suction fan until I reached #2 on the pressure gauge, then opened the blower, and removed the fan. I found the engine needed a lot of steam from the blower to create enough draft to keep building pressure. The climb was steady and before long the safety valves had blown.  

I set the reverser in full forward position, and opened the throttle just a little. I reached down to make sure the reverser was full on, and tapped the throttle and away it went. This locomotive ran smoother, and quieter than my others. There was a fair amount of exhaust, but it was a cold day, and showed up much more than I was used to. I found on the test rollers the locomotive ran almost by itself. 

All the controls for running the locomotive are placed so you can reach them easily. This is a great advantage to prevent burned fingers.  

Usually my locomotives run for about fifteen to twenty minutes, but this tender has a large capacity, and it ran for an hour. I added a little water to the tender, and a couple of times used the tender water pump just to maintain the half full mark on the water gauge. Aside from that, all I did was make some adjustments to the water by pass, and enjoyed watching my locomotive run. 

When it came time to close down the locomotive, clean up was much easier with the water drain in the tender and the removable alcohol tank. The blow down valve on the left side of the cab emptied any excess water out of the boiler. These are improvements that make an already great locomotive even better. 

The NKP Berkshire Kit has been a real pleasure to build and run. Aster has made many new and wonderful improvements. In addition, the Berkshire is now the largest locomotive in my collection. The size is impressive, the attention to detail is unbelievable, and it runs like a top. I am looking forward to many years of operating this great locomotive.


Southern Steam Trains is grateful for Howard Freedís generosity, expertise and willingness to write this comprehensive assembly review of the Asterís NKP Berkshire for positing on our web site. 


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