MJLogo Building an MJ Model Hints & Tips


These pages have been put together from information gathered from people who have built or are building an MJ model. They contain useful building instructions, drawing error corrections and other information.

It is by no means a complete list of modifications but should be of use to an MJ builder. I will update this section when I get more mods.

As far as possible the information is checked before adding to this section but no responsibilty can be accepted for any consequenses arising from use of this information.

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2" Burrell Gold Medal Tractor

2" Fowler A7 Agricultural Engine

Notes from Clive Manser - 10th March 2010

1. Smokebox Door Hinge.
The pitch of the rivets, as shown on the drawing, for the smoke box door ring is incompatible with the positioning of the smoke box door hinge. The drawing shows the hinges to be fastened to the side of the smoke box at one-inch centres, whereas, in practice I found 0.875" centres allowed the hinges to just clear the door ring rivets.

2. Valve Rods
The drawing for the valve rods will drive you crazy. The centre lines are confusing but after much thought I came to the conclusion that the 7/32" dimension for the number 2 Forward Rod should in fact be 15/64". In any event you may have to bend the rods very slightly to obtain a perfect fit to the expansion link.

2" Fowler A7 Road Loco

3" Fowler A7 Agricultural Engine

Drawing 0905 - Gearing

2nd Shaft
The dimension for the keyway on the right hand end should read 1 13/32".

Drawing 0907 - Cylinder

Cylinder Liner
A major change is that we have decided that the flanged head on the liner is not really necessary and the cast iron bar that we supply for the liner has been reduced in size accordingly. This means that you do not have to machine the counterbore in the front end of the cylinder bore to accommodate this flange. All other details of the liner remain unchanged.

Rear Cylinder Cover
The dimension for the slidebars to fit in was 11/16" should be 5/8" the size of the slidebars.

Drawing 0909 - Motion

Weighshaft Bracket
The measurement for the slide bars to fit into was 2 13/16" it should be 2 3/4". If you add up the two slide bars, the crosshead and the crosshead slippers, i.e. 5/8" + 5/8" + 1 3/8" + 1/16" + 1/16" = 2 3/4".

Drawing 0910 - Brake Gear etc

Bottom Brake Band Fixing Position
Fred Nightingale has pointed out that there are three dimensions missing that are on the 2" drawing which help to position the bottom brake band fixing. The 2" values are shown with Fred's 3" dimensions hand drawn.
Bottom brake Band Fixing

3" Wallis & Steevens

Ariel - 5" Gauge Rebuilt Merchantd Navy Loco

General Drawing Errors

There are quite a few errors in the drawings by Keith Wilson. I was given a list of some when I took over MJ. Download Error List

Rob Speare, one of my customers, has put together a very comprehensive web site about Bulleid Locos and there derivatives. Also some notes on building the models from a number of other builders. Well worth a look if you are building the Ariel or are thinking about a new project.

The website is here Bulleid Locos

7 1/4" Gauge Bagnall Loco

Banall Price Valve Gear

One of my customers has identified an error in the dimensions of the Bagnall Price Valve Gear.

Using an on-line Valve Gear analysis program by Charlie Dockstaders, he has drawn up a list of the relevant dimensions.

If the program dimensions (highlighed in green) are used then it works better.

Program DescriptionDrawing DescriptionDrawing DimensionProgram Dimension
DriverWheel Dia6.3256.325
StrokeCrankpin Rotation Radias3.253.25
Main RodConnecting Rod14.7514.75
Motion Connect Rod lengthPendulum Lever connecting link6.8756.875
Vertical 00
From Crosshead 1.3751.375
Fulcrum lever upper 0.340.38
Fulcrum lever backset 00
Fulcrum lever lower 2.5632.546
Fulcrum diameter 1.1251.125
Radias Rod lengthRadial Rod9.8139.813
Radias Rod extension 00
Link Radias 9.8139.813
Link Rocking Lever lengthRocking Shaft Lever1.251.25
Link Rocking Lever angle 75 deg75 deg
Eccentric Rod length 7.1187.286
Eccentric circle dia 1.0001.000
Eccentric diameter 2.52.5
Eccentric angle 129.10129.10
Reversing Arm verticalWeighshaft Lever height1.3131.313
Reversing Arm backset 00
Lifting Arm lengthWeighshaft Lever length22
Lifting LinkSuspension Link2.8752.875
Reverse Arm pivot verticalAxle to weighshaft centre vertical6.0635.269
Reverse Arm pivot horizontalAxle to weighshaft centre horizontal8.258.821
Fulcrum centre pivot verticalAxle to Rocking Shaft centre vertical3.02.335
Fulcrum centre pivot horizontalAxle to Rocking Shaft centre horizontal6.56.768
Reverse Arm to centre normal 0.80.8