By David Bantoft
THE INGREDIENTS
The picture shows most of the basic ingredients, being from left to right of the photo:
· 1/8” ID brass tube for the front axle;
· 19mm wide x 0.45mm thick brass sheet for the motor mount;
· 45mm wide x 1.0mm thick brass plate for the chassis;
· 28T x 48 pitch spur gear;
· 2 only 1/8” threaded 5-40 axles (now available new from Werner at Ace Hobbies);
· new replacement Scalectrix motor with 8 tooth pinion fitted (I used an OZ motor with end bell drive however it would be easier to use a Sakatsu with can drive);
· Cox front and rear Ferrari formula 1 rims;
· Static model tyres for the front rims and one sponge donut for the rear rims; and
· A Sakatsu trailing guide flag.
What is not shown is a full length Fly driver with open face helmet; 1/8” bronze bearings for the rear axle; 1/8’’ x 40 lock nuts, balsa wood for the body mounts and axle spacers.
Although the photo shows the chassis complete and the body/interior ready for mounting I will briefly run through the methodology for the build.
Having compiled the ingredients I then sat down with a piece of graph paper and laid out the centre line and the track and wheelbase required for the 250LM. I then pencilled in where the model’s interior would sit thus making sure when the angle bracket for the motor was drawn in the motor would not foul the back
of the interior panel. As it happens it did, so I cut a clearance notch out of the interior panel behind the drivers seat. I then measured up the wheels/tyres, motor, gear etc. and drew it all onto the graph paper so it fitted within the body and around the interior. After doing that it is then possible to copy the layout onto the brass plate and decide where cut-outs have to be made are not required (i.e around the wheel wells, the motor etc.
While writing the article I thought it might be beneficial to do a rough sketch just to show what I am talking about. I hope this makes up for my lack of skills in translating what I do to words!
It was at this stage that I decided the trailing guide was not required so I used an ordinary guide and relieved the chassis in front of the front axle line to recess the guide.
At this point in time I would like to say that it still takes me more than one go to get most of my chassis’ right. The LM took 2 try’s but I have saved the first basic chassis platform for another project. The rear axle is mounted, via the bronze bearings, in the motor bracket and the front axle is mounted by bending the area under the front wheels up at 90° to the chassis pan and cutting a slot for the axle in both sides.
After assembling the chassis and trial fitting it its time to complete and mount the body using balsa wood blocks superglued to the inside of the body. I then drilled through the brass chassis pan and screwed 4 2gge screws through the chassis holes and into the balsa. For additional strength the ends of the balsa and the screw holes have superglue run onto/in them and let to set. You then have the equivalent strength of having used a hardwood without the difficulty. It may be necessary to notch the balsa wood to clear either end of the motor (see balsa block on drivers side inthe above photo).
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