Errors on drawings

[JonL]

What gauge is it, 5"? I'm trying to compile drawing errors on another site but don't have anything on the Wessie.

[William A]

I would like to build a Maid of Kent with the platework cosmetically altered a little around the splashers and cab to represent an earlier SECR 4-4-0. The E-class is close enough for rock and roll, visually: i.imgur.com/T1aB64H.png

I have been pointed to this forum to ask you kind people to give me a hand with establishing which set of drawings to use to get an inside-cylinder, Stephenson valve-gear version working. Does anyone have any strong opinion? This would be my first loco build so something which is workable but simple would be preferred over complex-but-perfect. Any ideas?

[JonL]

Might be worth starting a seperate thread on the main board to give your request visibility. I'm still a novice too, People have been very helpful here.

[pete3417]

I am just trying to restart on the Rob Roy I started many years ago and have come across various mentions of errors on the drawings - I started this in the late 70s so apparently have early incorrect drawings. I had noticed that there was a problem with fouling of the valve links and now understand that this wasn't my fault. There is, or was a website set up by Alan Stepney listing much of the errata in published drawings but this no longer seems valid. Can anyone advise if this has moved or where this information may be found. 
Thank you in anticipation. Pete

[gwrfan]

Feb 5, 2021 19:44:19 GMT pete3417 said:

I am just trying to restart on the Rob Roy I started many years ago and have come across various mentions of errors on the drawings - I started this in the late 70s so apparently have early incorrect drawings. I had noticed that there was a problem with fouling of the valve links and now understand that this wasn't my fault. There is, or was a website set up by Alan Stepney listing much of the errata in published drawings but this no longer seems valid. Can anyone advise if this has moved or where this information may be found. 
Thank you in anticipation. Pete

Hi Pete,

Try here:

web.archive.org/web/20080821135852/http://www.alanstepney.info/page43.html

Geoff

[gwrfan]

Feb 5, 2021 19:44:19 GMT pete3417 said:

I am just trying to restart on the Rob Roy I started many years ago and have come across various mentions of errors on the drawings - I started this in the late 70s so apparently have early incorrect drawings. I had noticed that there was a problem with fouling of the valve links and now understand that this wasn't my fault. There is, or was a website set up by Alan Stepney listing much of the errata in published drawings but this no longer seems valid. Can anyone advise if this has moved or where this information may be found. 
Thank you in anticipation. Pete

Hi Pete,

I tried pasting the link, but it failed to work, so here, hopefully, is the text:

Rob Roy. 0-6-0T in 3½" gauge by Martin Evans.

If built to the drawings (and I don't think they have been corrected yet), the valve gear and the valve
spindles don't line up. The difference is 1/8" (?), and the solution is either to make a stepped valve crosshead, or to make the valve face 1/16" further out from the cylinder, and the valve spindle 1/16" higher in the steam chest. (Thanks, to Steve Papworth.)

Change the pitch of the thread on one end of the valve spindle, to allow the setting of the valves to be more easily modified.

Fit thin locknuts to both valve and piston glands.

The bottom section of the crosshead pump is too close to the cylinders.

The blast pipe is in the wrong position.
Increasing the height of the blast pipe by about 3/8" seems to improve draughting.

The dome bushing on the boiler should be 3/4" diameter bore!

Geoff

[pete3417]

Thank you for the links. I will study with great interest! Very helpful.

[stevep]

Another little error on LBSC's Pansy drawings. The brake hangers are threaded 1/4" x 40T to screw into the frames. The frames are 1/8", and the dimension on the brake hangers gives the thread at 3/16" long. That doesn't matter on the driving wheel, as there is plenty of clearance. On the leading wheel, provided you have drilled and tapped the cylinder block as well, it again doesn't matter. But the trailing ones would pass through the frames where the boiler is.

Best to make the thread only 1/8" long.

[andyhigham]

I have just bought the drawings and book(let) for Martin Evans "Caribou". I could fill another 14 pages with errors and omissions.
The kindest thing I can say about the book is "vague".

[firebird]

Hi

I'm a bit late joining in this discussion but here goes.

My first loco build is Conway by Martin Evans. Its 95% complete now and just waiting for its second hydraulic test once our club is fully open again. As a total newby to live steam loco building I relied entirely on the plans (purchased from one of the well known suppliers) and with hind sight foolishly trusted that they were correct. I didn't follow any set procedure but made parts as and when time permitted and materials/castings were available. The frames were made early on as I figured since everything else bolts to them it would be a good place start. Many parts were made and bagged and tagged. One of the first things I made were the valve rod guides.



I made these from bronze castings. It wasn't until I tried to bolt them to the stretcher that things went wrong



Hmmmmm. 4 holes in the stretcher and 6 holes in the guides. I tried re drilling but made a mess of them so 2 bronze castings relegated to the scrap bin!

I encountered many errors rom thereon in but unfortunately I didn't record them all but here's just a few.

The blast nozzle



Which is made from a not too cheap piece of bronze has the wrong total measurement on it of 11/16" resulting in yet another item launched into the scrap bin.

The main error I came across was the length of the boiler tube, a very expensive piece of copper tube. Quite by chance I came across an article written by the designer himself Mr Martin Evans. It was the construction article published in 1980 in Model Engineer magazine. A bout 3/4 way through the article tis was in the text



Had I not read that a very expensive mistake was about to made.

Many more errors were encountered and had to be overcome including a complete strip down of the frames to re drill holes that were in the wrong place!

I think the point I would like to make is that some of these errors can be costly if not noticed in time. A lot of time can be wasted making parts that simply won't work or fit. As a novice engine builder its impossible to find them all but certainly things like the boiler tube shown as the wrong length should be corrected. The designer himself made reference to it 40 years ago but the plans still show the same error.

Cheers

Rich

[andyhigham]

My Conway has 6 bolts on the guides

[andyhigham]

The Caribou drawings and book are appalling
No drawing or description for :-
The smokebox door
The dome cover and sandbox
The cab!!!!
The running boards
The bell
and a multitude of other parts
Dimension missing for height of tender water tank

There is a detailed description of a hand pump though

[firebird]

Hi Andy

I made my valve guides with 6 holes but the motion plate already in the frames only had 4 holes. All as per the plans!

Cheers

Rich

[andyhigham]

Please don't make the cab to the drawing, it is way to squat.
Open suits the loco well
20191231_165208 by Sigma Projects, on Flickr

[cplmickey]

Jul 9, 2021 20:31:37 GMT firebird said:

Hi Andy

I made my valve guides with 6 holes but the motion plate already in the frames only had 4 holes. All as per the plans!

Cheers

Rich

Except the plans say to mark off from the VR guide so if you had done this you would have ended up with 6 holes in the motion plate surely? Ian

[uuu]

Jul 12, 2021 15:50:33 GMT cplmickey said:

.....Except the plans say to mark off from the VR guide so if you had done this you would have ended up with 6 holes in the motion plate surely? Ian

And, although you can guess the PCD of the ring of holes on the pump is half-way across the flange (dimension not shown) , the frame stay drawing has no dimension either, so you'd have to refer to the pump to figure it out.

Wilf

[JonL]

I've added these to the SmallLiveSteamEngines wiki to hopefully save some other poor soul.

[andyhigham]

Spot the glaring mistake
20210719_193322 by Sigma Projects, on Flickr

[mbrown]

".... and then drill through the nipple into the chamber"!

Malcolm

[andyhigham]

Two other things strike me on that drawing.
The knife edge seat for the ball will be very difficult to machine. Probably unnecessary too, I have never had a problem with a tapered seat with the ball sitting on the taper.
How do you machine the "rad to suit smokebox" without CNC?