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AlpinFlex Tiller Building Instructions

Introduction

With this kit you can build an AlpinFlex tiller for the Kässbohrer PistenBully 600 in scale 1:12.

For building the model some basic knowledge in modelling is necessary. This instructions should be viewed as a guideline, which is giving the most important points for building the tiller. Most of the drilled holes need not to be in exact locations, it is sufficient to drill them approximately in the same position as seen on the pictures. Of course it is up to the each modeller to apply changes or improvements.

I strongly recommend to take advantage of the large amount of available pictures for reference (e.g. on www.snow-groomer.com)

The kit is produced under license of the Kässbohrer Geländefahrzeug AG.

Contents of the Kit:

 

Additional Materials Needed for Assembly:


These materials are not included, but can be obtained in any hobby store:

  • Glue: Pattex Repair Extreme, UHU plus endfest 300 or similar

  • Paint: best results are obtained with an airbrush, alternatively spray cans can be used (be sure to use a spray can for modeling purposes)

  • sanding paper 600 grain for preparing the PVC prior to painting

  • Small piece of wood 200x900mm (plywood, wood, ...) or aluminum sheet to built a rig to glue the supporting frame together

  • hi-torque servo

  • servo mount

  • link from servo to lever

  • optional: screw drive instead of link

Drawing Sheets

These drawing sheets are necessary for the assembly:

Main Beam Assembly
Tiller Holding Frame
Main Beam
Main Beam Support
Supporting Rig

Main Beam + Support

Main Beam Support

The main beam support holds the main beam and enables the lifting and side movement of the tiller. The lever for lifting the tiller is attached here.

Thus the 20x20 aluminum-rectangle part is to be adapted as shown (see also the included drawing)

  • File front face to 15 degree as shown on the picture and the included drawing
  • 4mm-hole vertical for the side movement
  • 4mm-hole horizontal for the lifting movement
  • cutting and filing of a gap on the upper side (see picture) to insert the lifting lever
  • Please ignore the 4,2 mm dimensions in the CAD-drawings, a 4 mm hole is just fine.

Main beam support (top view)
Main beam support (side view)

 

Lifting Lever

  • Bending of the lifting lever as shown in the picture
  • fitting of the lifting lever into the main beam support, mark the holes and drill
  • Drilling of a 3mm hole for the lower fixation of the lifting lever
  • 45° countersink at the main beam support (see picture above)

Bending of the lifting lever		  
Mounting of lifting lever in main beam support
     

Tiller Lever

The tiller lever enables the option to attach it to the main beam either fixed or moveable. So far the fixed attachment has been used successfully. In this case the lower left hole with the countersink is not necessary. If you want to keep shocks from surface bumps from the servo you can insert a tension spring (no pictures are available for this option yet).

Holes have to be drilled into the 15x15 aluminum U-profile as shown:

  • 3mm hole for rotating bold or to fix the lever add a second hole.
  • 3mm vertical to attach the holder for the tiller holding frame
  • Optional: 3mm + 45° countersink to attach the tension spring, cut a thread at the other end

Advice: for cutting threads a simple one piece 3mm thread cutter is sufficient, which costs a few Euro. A 3 piece thread cutter set is not necessary for aluminum.

 
 
Tiller lever and connection with the main beam


Main Beam

The 16x16 aluminum block has to be attached to the front end of the main beam, which has to be grinded according to the drawing. Drill a 4 mm vertical hole.

Drill the following holes on the main beam (see also the included drawing):

  • 4x 3mm + 45° countersink to mount the 16x16 aluminum block
  • Thereafter drill 2,5mm holes into the block and cut 3mm threads, from both sides approximately to the middle
  • 3mm + 45° countersink to mount the tiller lever
Pictures show the assembly of the main beam parts


Tiller Holding Frame

The tiller holding frame consists of the pre-bend parts. Drill a 3mm hole in the middle of the 10mm aluminum pipe. Add 8.5mm holes at both ends in a distance of 66 mm (center - center) from the middle hole. Cut off surplus material at the ends (not yet done in the pictures).

Insert the pre-bend 8mm pieces into these holes. For gluing it is recommended to make a supporting rig out of a piece of wood (see drawing) or aluminum.


Supporting rig made from wood		  

Supporting rig made from aluminum (alternatively to wood)
Carefully adjust the 3 parts on the support and glue with UHU plus endfest 300. To achieve the necessary strength a hardening in the oven is mandatory (180° C, 5 minutes, see instructions of UHU plus).

Advice: wait for about 2 hours before hardening in the oven. After this time the glue is already solid enough that it doesn't flow away when heated.

The strength of UHU plus endfest 300 after heat treatment is really extraordinary. Grind the areas prior to gluing and carefully decrease them.

If you can't get UHU plus endfest 300 look for a 2 component epoxy glue, which can be hardened under heat.
 

Tiller holding frame (already assembled)

After cooling down the glue is cured and the work on the frame can be continued. Cut the ends of the side parts vertically according to the drawing. This can be done with a power side cutter (use safety glasses!) or by hand. Then finish the cut surface with a file. This task is a little bit time consuming and tricky, because the frame cannot be really well fixed for the working tasks. But with some patience and filing it is not difficult.

Cut 3mm threads at both ends of two of the 6x6 aluminum rods (see picture):

Threads at the end faces		  

Then place the front and rear frame holders onto the 6x6 rods and screw the rods to the end plates (3x10 flat head screws). The quadratical holes of the frame holders have to be filed first (see further down below at "tiller").

Now the holding frame and the frame holders can be adjusted accordingly. Maybe some further filing at the end surfaces of the holding frame is necessary to make everything fit nicely. Apply a 3mm thread at the upper ends of these surfaces (see picture above). Then mark the hole at the frame holders, disassemble and drill + countersink (see picture below).

 
Details of assembling the holding frame. The covers will be added later. This picture was made at the almost finished tiller.

Now reassemble again, add screws (M3x10 countersink) and mark the positions for the threads (8x) to mount the finisher rubber mat (see picture above). These should be applied in regular distances in between the gaps left, right and in the middle. Disassemble and apply M3 threads.

Also add eight M3 threads at the 3rd 6x6 rod for the downholding-screws of the finisher, distance approximately 40mm.

Now the frame is ready to be glued with UHU plus endfest 300. It is necessary to add glue between the frame holders and the surface, as well as between frame holders and 6x6 rods. See picture below for application of glue and harden glue as described above.


Frame and frame holder ready for gluing.


Details of the glue application. Don't forget the surface behind the philips screws!

The clamp to attach the holding frame to the main beam is bent out of the supplied milled part.

The holding frame will be attached to the main beam by this clamp as shown in the picture. Make sure that the tiller can move around the vertical mounting screw (tilting movement). If necessary the 15x15 U-profile needs to be filed accordingly.

 

 

 		    

Covers

Now the (meanwhile painted) covers can be mounted. First measure the exact position of the frame holders and cut slots into the covers at these positions (see picture further above). Then carefully insert the covers without scratching the paint. If everything is fitting, add Pattex Extreme glue to the covers and the 6x6 rods, let it dry for a few minutes and press parts together. Take care to not mess with the glue. The tiller should now look like in the pictures below:


Tiller

The tiller itself is assembled out of the milled tiller teeth, the distance parts and the 15x15 rod. There are four different tiller teeth, which are tilted by 22.5°. First the strips holding the teeth on the metal sheet need to be removed with a file, and also the round corners need to be filed to a quadratic shape (see picture).


Then add all teeth and distance parts onto the rod. Start with a teeth part. If they do extend over the rod, just grind the distance pieces over a file clamped in a vise: for example 23x0.1mm = 2.3mm - therefore not really much has to be removed. Striking each part 1-3x over the file should be sufficient.

If everything fits, glue the tiller together. Pay attention to the correct order of the teeth, so that a regular screw pattern is achieved. Put some glue on the edges of the rod and the faces of the distance parts, thus adding piece by piece. Harden the glue in the oven like described further above.
   

Finally glue the short pieces of brass pipes into the black plastic covers, and glue these into the ends of the 15x15 rod. Please do NOT harden them in the oven, as the plastic will melt.

The tiller is attached with M4x16 screws + nut + spacer to the frame. All kits which were delivered after December 2008 contain a shorter tiller to make room for a second counter nut on each side.


Finished tiller

 

Finisher

Use the supplied grooved rubber mat for the finisher. Probably in early 2009 a plastic version of the finisher including side finishers will be available, which can be added.


Finisher + mounting stripes

To mount the finisher cut fitting pieces out of the alu stripes (see pictures) and apply 3mm holes + countersinks, fitting the threads at the 6x6 rod. Small slots at both ends have to be cut out (see picture above).

Remove some of the rubber with a chisel (or a knife) as shown below:
 
Attach the finisher to the pressure bar (6x6 rod) with M3x25 screws. Drill 3mm holes into the rubber + countersinks (see picture above right and below). Drill 3mm holes into the aluminum stripe and mount it together with the finisher.
 

  

The finisher can be built much closer to the original, as Adrian Humbel (Switzerland) has done it:

A groove was added to the 6x6 rods lower ends, so that the small arched supports fit in. The small arched supports were bent from a 4 mm steel wire and a small piece of 4mm steel wire was soldered to the left and right ends, which a thread to fasten the finisher. Between arched supports and finishers an aluminum stripe (with more thickness than the supplied stripe) was mounted, with a small sealing rubber under each support.

 

 


Support

The support for the main beam is bend out of the supplied milled part. The bending lines are pre-milled, so that an exact bending line can be achieved. Best is to bend it around the 20x20x20 U-profile of the main beam, then the inner dimension will be exactly 20mm. The upper left area will be filed later, because the link for lifting the tiller has to go through here. To mount the support on the chassis tub drill two 3mm holes at the bottom end and one hole at the upper right corner, all with countersinks.

To increase the strength of the chassis tub bend the supplied sheet metal in U-shape, and drill 3mm holes. Use the already existing holes at the side of the tub, and 4 additional holes at the back side (see pictures below).

Strengthening sheet		  
Strengthening sheet on the tub

The support is attached to the sheet directly with the tow lower screws, the upper screw will go through sheet and tub (see picture below).

In order to get the link for lifting the tiller through the tub cut and file the hole as shown in the picture.

As can be seen in the picture to the right, the "ears" of the support have to bend outward. Their function is to force the main beam into a central position, if the tiller is tilted sidewards before lifting. Mount the main beam and make sure that in every possible position a lifting can be done without blocking or getting stuck. Also round the upper edges of the main beam in that area with a file.
 
The support holds the tiller in a vertical position when raised.
 

 

Servo Mechanism

There are several possibilities to lift/lower the tiller, two of them are described here:

  • Lifting with a winch (with a winch servo)
  • Direct connection with a servo (not recommended)

Lifting with a Winch (Recommended)

The solution which is presented here was realized by Adrian Humbel (Switzerland). Many thanks for the friendly submittal of the pictures.

Advantages: the small lever arm yields abundant force. The tiller can freely move upwards when driving through a ditch.,
Disadvantage: no pressure can be put on the tiller

Unmount the gear box and remove the left side plate. Then cut off the "ear" as shown in the lower right picture.

Solder a lever with the supplied brass parts as shown below. Prior to soldering drill 2mm holes to attach the ball links. On the left side you have the option to place the connecting rod below or above the motor gear. The longer lever is to be used on the left side (in the picture both levers are still of the same size).

 
Lever   Gear box with adapted side plate

In this case a winch servo ist used, like it is used for moving the sail in an RC sailboat. The supplied winch drum must not be used, because the force would be much too small here. It is sufficient to wind up the rope around the servo shaft. This results in an enormous rope force due to the small lever arm. To prevent the rope from spooling off a regular servo disk should be mounted on top. A more elegant solution is shown in the pictures. Adrian Humbel manufactured a little drum. If you're familiar with servo electronics you may convert a regular servo to a winch. The rope will easily go underneath the motor. A rope with little or now lateral stretch is recommended.
 
The servo mount and drum are not supplied with the kit.

To adjust the servo movements first mount the main beam without tiller and check everything carefully for free movement and end stops. Limit the servo movement accordingly, if your sender has this option. If a winch runs against a mechanical stop it will be destroyed within a few minutes, or it will damage other parts of your model with its enormous power.


RC sail winch for lifting the tiller. The winch drum is self made.


Details for sail guiding and installation.

 

Direct Lifting with a Servo (not recommended!)

This method was first realized, but did not perform well in practical use.

Disadvantages: very powerful servo is necessary, high power consumption in lifted position, no compensating movement possible if driving through a ditch, which should be permitted via a spring in the linkage (not described here).
Advantage: a pressure can be put on the tiller. But it is questionable if this advantage compensates for the above mentioned disadvantages.

Unmount the gear box and remove the left side plate. Then cut off the "ear" as shown in the lower left picture.

Solder a lever with the supplied brass parts as shown below. Prior to soldering drill 2mm holes to attach the ball links. On the left side you have the option to place the connecting rod below or above the motor gear. The longer lever is to be used on the left side (in the picture both levers are still of the same size).

Gear box with adapted side plate		  
Lever

The lever will be placed on the rearward black rod of the gear box and secured with the supplied adjusting ring.
 
On both pictures below the whole mechanism is shown like I made it: the rod is placed below the engine gear. Alternatively you can stay above the gear and use the already existing servo mounts at the front, where the mechanical speed controllers were attached.

I have used a hi-torque servo, which should be able to achieve 130Ncm (or  a"13kg" servo) according to the manufacturer. This torque should normally be sufficient. Obviously the servo doesn't achieve this torque, as it barely can lift the tiller. You can either use a more powerful servo or use a winch as described above.

The servo mount and rod are not supplied with the kit.

To adjust the servo movements first mount the main beam without tiller and check everything carefully for free movement and end stops. Limit the servo movement accordingly, if your sender has this option. If a servo runs against a mechanical stop it will be destroyed within a few minutes.

Suggestion for connecting to the servo.


Suggestion for connecting to the servo.
     

Stickers

Finally the silver PistenBully stickers will be applied. They come with a protecting paint, but nevertheless should be handled with care, as they can be easily damaged by scratches.

Also apply the warning stickers as shown below:

The gap between both covers will be closed with black textile tape.

Both black painted "humps" are cut accordingly and glued with Pattex. The cover for the hydraulic controller can be attached in the middle (not shown on the picture).

If want, you can add hydraulic hoses according to the original.


Optional: Lifting Cylinder

The hydraulic cylinder can be assembled from alu-tubes (10 x 46 mm and 8 x 41, 8 x 5 mm) + ball heads as seen on the pictures. If the thinner tube does not fit into the cylinder, it must be grinded a little bit. The easiest way is to clamp it in a drill stand and holding a file against it. Finally polish with fine sanding paper on the drill stand.

The ball heads must be cut to fit into the tubes. The left ball head should be shortened as shown, so that the piston rod can be fully inserted. Glue with epoxy glue.

To mount the lifting cylinder on the main beam the two small lashes of the milled parts are to be used. These should be mounted in an angled position inside of the main beam. Please carefully check that the lifting cylinder is not blocking any movements.


Parts of the lifting cylinder


Lifting cylinder

 

Sources for Materials

Hobby stores
Conrad stores or www.conrad.de
Modulor Materials www.modulor.de: aluminum pipes and rods, rubber mats


Photo: Kässbohrer Geländefahrzeug AG
AlpinFlex Tiller - original ...


... and model (as supplied with the kit)


... or with some improvements