Martin Finney 7mm A3

Discussion in 'Area 51' started by P A D, 19 January 2018.

  1. P A D

    P A D Western Thunderer

    Before going further with the chassis, I thought it would be good to get the coupling rods on. Here they are after laminating and fettling.

    And on the wheels.

    I'm pleased but not surprised to say, that the wheels turned without the slightest hint of a bind. So with that confirmed I removed the wheels and completed the soldering of the spacers. I then refitted the front and rear wheels, spaced them centrally with cut up strips of card, and soldered the bearings slightly proud of the frames. There is now minimal side play front and rear and no need for any axle washers.
    On the right hand frame there are two fold down brackets. The rear most one can be folded without problem, but as can be seen in the photos, the front one will foul the wheel if folded at 90 degrees. I need to check the instruction further on to suss out why that is.

    As a parting shot I cut out and fettled up the frame for the cartazzi truck.

    I slotted in the truck to check the fit. It will need a little bit of fettling to get it sliding freely, but not much. Again the fit of the parts is excellent.

  2. mickoo

    mickoo Western Thunderer

    You need to cut a small fillet out of the front lubricator bracket to clear the leading wheel flange.

    Remove the front wheel, fold the flange 90°, strengthen the inside of the bend with a fillet of solder and then use a slitting disc in a dremel and ease a slot in the bracket (allow for side play) to clear the leading wheel flange. Pop the wheel back in, job done :thumbs:
  3. P A D

    P A D Western Thunderer

    Thanks Mick.
    I wondered if was an error on the drawing, but didn't check further in the instructions before I packed up.

    As you say it's easy to remedy.

    In the end I decided to punch out the rivets on the frames, but have not bothered with opening the rear hole.

    I found this photo on the web of FS being re wheeled. The frames bear out your pre 1933 drawing. Rear most oval hole blanked off with a smaller round hole in front of it.


  4. P A D

    P A D Western Thunderer

    Here's the chassis on test on a slight incline.

    It runs smoothly under its own weight,
    so I removed the wheels to add some details. The dummy etched hornblocks and some half etched overlays on the outside of the frames have been added. The centre bearing holes have been elongated so if it doesn't run smoothly when I put the wheels back on, I'll know I've cocked it up.

    I've also modified the lubricator bracket to clear the front wheel as suggested by Mick. It is actually mentioned in the instructions but i didn't spot it first time round.

    The cartazzi slider now moves smoothly in the rear frame. It just needed a little tweek to the folded bearing surfaces in the frame.
    Last edited: 14 February 2018 at 19:52
  5. P A D

    P A D Western Thunderer

    So here are the bearings after adding a "dimple" with an 0.8mm drill, and the wire springs made from 0.7mm ns wire. The longer bends are to ensure the locating spigots at the bearing ends are vertical when fixed to the inside of the frames.

    Here are the springs soldered in place.

    And with the bearings added.

    And with the wheels back on. I've tested the running again on the inclined track and it runs smoothly.


    Next the rear inner frame for the cartazzi truck has been added. 20180216_183909.jpg

    And with the truck in place.
    The truck is held in place by the 0.8mm ns wire which also offers some degree of side control.


    The bogie wheel splash guards, middle sand box filler pipes and front sandbox castings have also been fitted.


    Here are the outer rear frames and drag beam under preparation.

    The text part of the instructions is on A4 paper folded into a small booklet, so easy to handle. The assembly and fret diagrams are on A3 paper so less manageable on the workbench. To keep them out of the way but handy to view, I tape them to the wall as in this shot.