PistenBully 100 Park
by Albert Tuertscher
As a little brother for my PB400 ParkPro 4F I'm now building the newly introduced PB100 Park. The challenge is that body, chassis and auxiliaries are practically all completely new designs. And furthermore the smallness of the snow cat brings additional challenges in utilizing the limited space.
The original is also a completely new design and features all the high-tech parts of it's larger brothers, like the 4F exhaust gas aftertreatment and the new operating concept in the cockpit.
The company Kässbohrer kindly gave me access 3D data as an excellent base for creating a true scale model. By the way I have a license agreement with Kässbohrer since 2007
PB100 Park (original) at the Kässbohrer location at Grand Junction, Colorado
PB100 Park (original)
Checking out the PB100 Park :-)
End of September 2018 I could inspect a PB100 Park at the Kaessbohrer office for the Rocky Mountains. I made almost 400 detail photos. A big thank you to the great folks there, who put the PB100 in the center of the lot for me.
The first step is always to design the chassis as a base for the snow cat. The JC model serves as a motivator only.
Here I'm relying as much as possible on parts by Pistenking. Not only because it makes it easier, but also as they actually correspond to the original. For example the track tensioning mechanism by Pistenking is the same as at the original.
But I cannot use the flex shaft drive because the bending radius would be much too tight.
Instead, I'm making a gear set with bevel gears and spur gears, on the left you can see this in the CAD model. The gear box housing will be printed and supported by laser cut metal parts.
In the picture below I positioned the hydraulics components (green blocks) in the chassis for checking if they really fit. At the front is the pump, in the middle a 6-valve block (which I have available since the conversion of my PB400 ParkPro), and at the back a single valve.
It’s always exciting when the first parts arrive: above are the first printed parts for the sprocket gear box (front black), the sprockets, the master form the wheels, the frame for the backpack, one air intake and small parts. I eventually didn’t use this air intake of sintered nylon.
The above right picture shows laser cut parts for the chassis and platform, gears and the hydraulic pump.
I could finish the chassis over the Christmas Holidays 2018/19. Wheel arms, suspension and track tensioner are standard parts by Pistenking of which some needed to be modified. The metal sheet parts were glued together in the proven way with UHU plus endfest 300 in the oven. Attention: the generally available version has a new formula and is by far inferior to the old version, which is now only available for commercial purposes. My advice: make sure to use the old version.
Finished chassis. The side sheets are exactly like the original.
Side sheets at the original
Chassis under construction
Secondary gear drive
Suspension and track tensioner
The tracks consist of Pistenking parts which again had to be modified. The cleats were delivered raw. On my Stepcraft CNC mill exact holes could be drilled very efficiently. The wheel guidance parts needed to be cut on a capping saw to fit the narrow wheels. The wheels are casted parts of PU resin which I finished on the lathe.
To assemble the track I made a device out of wood with the exact cleat distances. This allows working very accurately and fast. In addition I treated myself with a Proxxon Micro Screwdriver, a highly recommended tool especially when one has to turn in 368 screws.
CNC drilling of the cleats
Cutting the wheel guidance parts on the capping saw
Ready for assembling the tracks
Tracks at the original
I even found a few snow patches in my backyard for the maiden drive to make this event appropriate for a snow cat. Everything worked well right on and the little snow cat moves as planned.
Maiden drive on Jan. 9th, 2019 at 4 pm
Printed parts for the driver cabin
The printed parts for the driver cabin arrived on Mar. 6th, 2019. For higher strength I had the cockpit base and side frames printed in sintered nylon. All other parts are printed in high resolution because the details are much better represented. Also I'll save quite an amount on sanding work. But they're considerable more expensive than the nylon parts. But it is really impressive how even smallest details can be seen.
I had the side air intakes also printed again because I did change the rear side to match the latest version.
The picture below shows the printed parts for the mirrors and worklights as well as for the holders and the railing.
The brass printed parts have been combined as usual to save costs. They are then cut and for the long straight parts I soldered 2.5 mm brass tubes to them.
Also the door hinges are brass printed parts and correspond to the original. In order that they are on the same axis and the door can be opened I aligned them with a long steel wire for glueing.
The door is hold in place in the closed position by neodymium magnets. They are glued invisible in the cabin frame, as counterparts serve steel wires in the door frame.
The fine printed parts have to be carefully sanded to remove the unavoidable printing steps.
I first primed them with gray paint and then wet sanded with 360 grain sand paper. The gray primer remains visible in the grooves of the steps until the surface is smooth. This process had to be repeated several times.
Then I prepared the surface with 400 and 600 grain sand paper for painting.
Sanding and painting required considerably more time than anticipated. At the end it were months until all parts were sanded and painted. Unfortunately there were some mishaps at painting which added time and was annoying.
The windscreen was vacuum formed from polycarbonate. For this a mold had to be made on my Stepcraft. As done before I milled it out of Sika block, which I sanded afterwards and painted it with heat resistant paint. Then I polished it to a high shine.
The painting and assembly of the cockpit ceeling in the picture above is finished. All black parts are separately printed pieces which makes sanding and painting much easier.
The feet area (here on the driver's side) is also made corresponding to the original. The feet rest is a brass printed part. The air nozzles are separately printed parts, so I could glue them in place in random positions.
The original features a fire extinguisher underneath the foot rest on the passenger side. As I could not find a fitting one I made one myself as a printed part. Of course the right sticker cannot be missing. So I draw it according to the original and had it printed in white. Now I have more than enough such decals to open a fire extinguisher store in 1:12 and 1:8. :-)
To glue the driver cabin parts together I used UHU plus endfest 300. This gave me enough time to carefully align the parts. But it needs 12 hours to cure. I glued in multiple sessions. Finally the windscreen was glued in place. For this I used a special glue for plastic scale models (Microscale Micro Kristal Klear) which was developed exactly for that purpose and which cures absolutely clear.
The driver seat as "'captain's chair" is not only a highlight at the original, but also at this model.
The PB100 has exactly the same newly introduced control console as his big brother, the PB600 Level Red. Of course I had to make it as detailed as possible for this model, and I'm excited that even finest details like the PistenBully logo on the screens back side are visible.
The screen is lighted from the inside by 2 SMD LEDs, the wires are passed through the hollow printed screen arm.
The console support frame is also like the original (picture below right).
The new LED worklights with their characteristic cooling fins are a real challenge in 1:12 because not much space is left to fit in a LED.
I installed an up to the minimum flat sanded 3 mm LED. Probably a SMD LED would have been easier, but I have more than enough 3 mm LEDs in stock. The worklights are installed with tiny M1 screws.
As more and more the lower and flat beacon Comet S is used at the original I had to have them for my model, too. For this I modified a Pistenking rotating beacon. The base socket had to be hollowed out on a lathe so that the LED-board would fit in it.
The orange cup was shortened and sanded flat on top and polished. Only a thin film of plastic remains on top. A really delicate modification, and all too easy the electronics may be damaged (see picture to the right).
To comfortably switch the individual light functions I'm using the Pistenking Kingbus system as in my other models. Pistenking delivered the Universal Modules "naked" without housing and plugs. Otherwise they would not have fitted into the roof. Therefore I had to solder the wires.
"Naked" Kingbus Universal Module
Flashing beacons and hazard flashers live
In parallel to the body parts I could finish all additional parts like mirrors, worklights, inner covers of the doors, seats and stickers. Therefore the final assembly with all details could be done relatively quickly.
On July 25th, 2019 the moment had come to say "Please have a seat in the driver's seat".
Detail view of the mirrors and the flat warning beacon
Size comparison with the PB400 ParkPro 4F
End of August 2019 the printed parts for the backpack and the wipers were delivered.
The exhaust aftertreatment system is printed with a new material in stereo lithography. The details come out really good. This material is considerable more durable than the transparent resin from which the ultra high definition parts are printed.
As usual I combined the parts to groups to save costs.
For the exhaust aftertreatment package and the cooling package I made all parts which are visible. Especially for the exhaust parts several sanding sessions were necessary to achieve a smooth surface. The exhaust pipe is silver when new but de-colors quickly in operation and gets rusty. I had to use all my painting tricks here.
Cooling package with tank pipes for Diesel and AdBlue
Exhaust aftertreatment: left the particulate filter, in center the AdBlue mixer and right the catalyst
The locking mechanism for the driver cabin is visible, too, and therefore I made detailed parts of it. At the original the brackets of the cabin click into the golden lockers which can be unlocked hydraulically. The parts are moveable at the model and are pushed in place by the spring. For stability they are brass printed parts (pictures above).
The park blade design is finished in CAD. It will be built in the proven way with glued 0.5 mm aluminum sheets and brass printed joints.
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