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Member postings for David Wasson

Here is a list of all the postings David Wasson has made in our forums. Click on a thread name to jump to the thread.

Thread: Beginner's engine build. Simplex 5"g.
09/06/2020 17:05:52

Perhaps distortion has happened to those that had frames that were particularly narrow. These frames are pretty wide. I certainly had no problem with distortion. Hopefully, it was not just luck!

09/06/2020 14:37:50

Yes, sometimes BMS will distort when you stress relieve it, like cutting out the space for the axle boxes. I used 1/8" BMS, and it did not distort. Although, I did make sure that the material was as flat as possible before cutting. Also, to a certain degree, the frame spacers and front and rear beams will keep the frames straight. Make sure everything is perfectly square when you clamp and drill for the screws that hold everything together.

09/06/2020 10:36:39

No problem, happens to everyone.

09/06/2020 10:36:24

No problem, happens to everyone.

08/06/2020 17:04:10

The eccentric is mounted on the front axle. There is plenty of room for the eccentric strap.

30/05/2020 19:06:56


Congratulations on getting a mill! It will really make short work of things that you might otherwise be using a file. I assume you already have a lathe?


29/05/2020 10:50:10

Iain, check your Private Messages, I have some additional build information you may be interested in.


28/05/2020 23:56:21

Having built a Super Simplex, it is not perhaps a "beginners" locomotive, but, it certainly can be treated as a first locomotive for a model engineer with some experience. I would probably never recommend building a locomotive as a way to learn model engineering, the learning curve would be pretty steep this way. An easier way to start would be to build a stationary engine before moving on to a locomotive.

The "simple" thing about Simplex, is that it is devoid of all the detail components that can make a locomotive build seem to go on and on forever. It is designed to get you on the track in the least amount of time with a locomotive that has a real locomotive style boiler and valve gear that operates much like the full size and can be notched up. Six driver wheels for plenty of traction, and no tender to build. A freelance design that can be made as detailed as the builder chooses, or, just as drawn. Yes, there are problems with the original Simplex, and some of the issues were addressed with the Super Simplex.

I got my chassis running on air in 9 months and running on it's own steam on my club track in 23 months.

As for getting oil to the main bearings, yes, there is nothing about this in the drawings, only the oil holes in the axle blocks and in the horn block castings as shown in the Super Simplex drawings. I created mounting blocks for oil cups and made 3/32" pipes to connect the oil cups to the horn blocks to allow the oil to drip in to the cup on the top of each of the axle blocks. I added a small wool punching in the oil cup so all the oil would not run out. The forward, center axle and eccentric strap for the axle pump have an oil cup mounted on a little block tucked under each side of the boiler. The aft axle has oil cups mounted on blocks inside the cab. A long spout oil can and a stick to open the lid of the oil cup makes it actually easy to oil all the main bearings and the axle pump strap.

This oiling system I installed a year after the locomotive was built. Not hard to retro-fit. The first year, I simply oiled up in the steaming bay from below with a long spout oil can.


dscn1816 - reduced 3.jpg




Edited By David Wasson on 28/05/2020 23:57:00

28/05/2020 23:01:54

The "draughtsmans smudge" is clearly the end of the valve rod. The upper drawing shows the rod in place and the rod terminates inside the boss with a little space between the ebd of the rod and the bottom of the blind hole in the boss.

In the lower drawing, the "draughtsmans smudge" dissappears because the drawing does not show the valve rod in place, or the slide valve, or the packing nut.

27/05/2020 22:33:33
Posted by Simon Collier on 27/05/2020 22:21:18:

Iain, there is a lot of stuff on Simplex over on MECH forum,

and build logs on the net generally. My Simplex was built by a sheet metal worker and the plate work is lovely. One thing that makes life difficult is that the whole superstructure is one piece. I want to take the turret off to fit a new one with more valves, but I first have to remove the whole cab and tanks assembly.

Yes, having the tanks and the cab in one piece makes things difficult to be sure. I made my tanks separate from the running boards and the cab.dscn1861.jpg

27/05/2020 01:19:09

This dimension is confirmed in ME Dec 1968 for cast horn blocks also. The opening should be 1-5/8" by 1-1/4".

27/05/2020 00:20:41

The horn blocks should be made to match the frames. Hornblocks should be 1-5/8" , not 1-1/2".

23/05/2020 15:02:42

I don't know how deep you are into your project, but, you might consider the Super Simplex. Evans corrected a few design errors on the Simplex and created the Super Simplex later on. Either design is a great first time locomotive and fun to drive. I have created a website dedicated just to the Super Simplex and has manys things in common with the Simplex. If you are building a "regular" Simplex you might still find some of the information useful.



Thread: Eagle 4-4-0 Main Horn Drawing Question
25/04/2020 13:49:49

The horn blocks are usually made from a casting with the webbing already in position, that's why there is not really any dimensions . The position of the holes for the rivets is also not critical. Just position the holes between the webbing and make them all look the same.

I have not built an Eagle, but, I have completed a Super Simplex by Evans. The horn blocks are pretty much the same as those on the Eagle.

Thread: Toilet roll hanging
29/03/2020 19:20:02

Live steam locomotives???

29/03/2020 14:03:48

Live steam locomotives???

Thread: Water pump
02/11/2019 20:05:09

Thanks John,

If you are interested in drawings for this pump I can probably help you out. Send me a PM if you are interested.

I changed which end the pump discharges from. I also made the intake holes in the bottom closer to the pump  body.  I also added a packing nut to the pump ram.  I usually use drawings like these as a point of departure and modify things as needed. 

Here's a link to a few photos of the construction of this pump:


Edited By David Wasson on 02/11/2019 20:09:01

Edited By David Wasson on 02/11/2019 20:11:40

01/11/2019 20:33:56

The hand pump for a Super Simplex by Martin Evans is pretty nice. Here's the one I made for my loco. It would work fine for a stationary boiler as well. This was all made from bar stock. It moves a lot of water and is easy to pump even against 100 psi. The handle on this one is removable, it's a stainless steel tube about 8 inches long.dscn1592 - resized 4.jpg

dscn1593 - resized 5.jpg

Thread: Making High Speed Steel Injector D Bits
16/06/2019 04:25:36

Excellent idea! Injector D bits from solid HSS.

Thread: boiler parts
09/06/2019 13:58:38

Yes, the two fittings at the top of the photo are for a water gauge. The two fittings in the lower half of the photo, I am not sure what they are. If they are injectors, they are unlike any that I have seen. No doubt someone else will be able to identify these.

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