A 'small' diesel scratchbuild

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gregh
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A 'small' diesel scratchbuild

Post by gregh » Thu Aug 20, 2020 8:10 am

A few years back I built a small Bo diesel for a grandson. It’s vaguely based on a sugar cane type loco. As usual, I first drew it up in LibreOffice Writer to check that the proportions looked OK and the proposed paint scheme and lettering.
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I used an Aristo block (ART29351) as used in their L’il Critter and RS3 locos. I removed the nice Aristo bogie side frames for future use. ( see the construction of my ‘big’ diesel, where they were used, here https://gardenrails.org/viewtopic.php?f=37&t=12904
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I then made up some side frames from bits and pieces, mainly to hide the motor block and the eight, AA, NiMH cells – I put 4 cells at each end of the motor block. That left the hood for the RC and sound.
cells.JPG
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The original frames were attached to lugs on the motor sides, so I used these lugs to attach the whole new base plate to the motor block. I cut the baseplate from 1.5mm styrene and contact glued 8mm timber under it to allow a screw to go through the lug and into the wood. Here’s the underside without the motor block. It’s 230mm long.
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The hood is cut from 1.5mm styrene with 0.5mm for doors and some cutouts for louvres. (Luckily I have a supply of ‘tropical’ insect screen used in northern Australia, which is just right for louvres!) The cross section size of the hood was determined by the 50mm dia speaker I mounted at the front. It’s contact glued in place over a 40mm hole and covered with 2 layers of (normal) flyscreen offset from each other. The hood top is 1.5mm styrene slightly chamfered around edges. Two 0.5mm pieces glued to hood for effect. It’s held on by 2 small magnets. The muffler is made from a ball-point pen casing and some wire. There’s no more ‘detail’ as it will be handled by kids.

Cab sides and ends from 1.5mm styrene with windows cut out and some small ‘frames’ of 0.5mm styrene glued on around windows. I painted the whole thing and then scraped the paint off the raised frames to show the white styrene. The window “Glass’ is overhead transparency sheet glued inside.
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While still in pieces, all styrene was washed in soapy water and allowed to dry for a day. Then undercoated with spray Primer and allowed to dry for 2 days before final coats.

The diagonal stripes on the ‘pilots’ were done by using masking tape cut out and painting red. Be sure to remove tape within a day of painting!
The numbers are wooden from a craft shop. Oval name plates are 0.5mm styrene with decals over. I needed a white background for the home-printed decals to show. The white lines on hood are adhesive vinyl.

I had a spare 433 MHz RC unit – these are used with a 4-button keyfob. The 4 buttons A, B, C, D are used for Accelerate, Brake, horn and toggle Direction, decoded by a Picaxe, which also produces the PWM motor control and controls the reversing relay.
A 2nd Picaxe produces the diesel sound. These all fit in the hood with the speaker. Once the hood roof is in place the sound is quite good for a simple circuit.
loco17cct capt.JPG
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Anyone interested in Picaxe can see my Tutorials here:
http://www.trainweb.org/SaTR/Picaxe%20tutes.htm



The on/off switch and charging studs (I use alligator clips) are located under the running board.

And here is the finished product.
ernie17 b.JPG
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Watch a 1 minute video here….
Greg from downunder.
The Sandstone & Termite's website: https://members.optusnet.com.au/satr/satr.htm

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ge_rik
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Re: A 'small' diesel scratchbuild

Post by ge_rik » Thu Aug 20, 2020 8:49 am

Great looking model, Greg. I really must get around to investigating making my own soundcards. It's been on the to-do list for at least eight years!

Rik
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ge_rik
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Re: A 'small' diesel scratchbuild

Post by ge_rik » Thu Aug 20, 2020 8:49 am

Great looking model, Greg. I really must get around to investigating making my own soundcards. It's been on the to-do list for at least eight years!

Rik
------------------------
Peckforton Light Railway - Blog Facebook Youtube

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Jimmyb
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Re: A 'small' diesel scratchbuild

Post by Jimmyb » Thu Aug 20, 2020 12:15 pm

That is a very nice little diesel, very impressed with your work (as usual) :)

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