Simplex Build August 2023

[philh1aa]

I received advice from more than one of my local club members to consider building something heavier than my current Rob Roy project.  Apparently, my local track has a relatively steep incline that light engines (typically in 3 1/2" gauge) struggle with unless they are fitted with large amounts of lead.  

I decided to build Simplex (the original blend) but with an eye on some of the Super Simplex modifications and comments/ suggestions that I have seen on this forum and other sites.

Progress so far;

I had two sections of 1/8" thick sheared steel plate just over 29" long (original Simplex size) that I have polished to remove the rust and milled to the correct width.  The milling operation was a bit of a challenge on my Chester 16V but it worked very nicely.  I now have surprisingly straight, parallel strips within 0.002" of the finished size.  I will try to post some pictures because the milling operation looks quite silly on my small mill.

I bought an old rusty, battered, bent, twisted chassis at least 3rd hand to scavenge some of the parts.  So far, I have salvaged;

1. A full set of the drawings in excellent condition along with the original photocopied simplex articles.

1. 6 off wheels.  They need to be cleaned up and probably skimmed, at least to define the 'tyre' but I will also check the runouts and crankpin centres.  They appear to be parallel treads - so I will ask my club which way to go i.e., stick with clean parallel or cone them?

2. 3 of the big heavy stretchers that have been very accurately cut.  They are nice and square and within 0.001" from the correct sizing.  Not very high value but it saves a little bit of time.  I will use the old frames as a drilling jig for the screws.

3. 6 cast iron axleboxes, springs and horn stretchers.  They are a really nice running fit on the axles so I will check their hole spacings and lightly skim if they are not central or at least the same position for the pairs.  Again, not high value but saves time.  I might also consider needle roller bearings?

4. An original gunmetal pump, eccentric and eccentric strap.  I know that the pump is a debatable design so Im looking for advice on what to do with it i.e., convert, scrap, modify etc?

5. A brass smokebox tube, nicely machined gunmetal rings at both ends and a very nice gunmetal smokebox door.  The gunmetal saddle appears to be fine but will definitely need some machining to match the tube and cosmetically clean the sides and front.  These are expensive items if I bought them new.

6.  I did start to cry when I examined the cast iron cylinders.  These need photos to make everyone else cry.  The actual cylinders are very nicely machined.  They are accurate with parallel bores, nicely fitted pistons each with 2 piston rings.  The outside surfaces of the steam chests are again, nicely machined with nice cylinder and steam chest covers.  Sounds great until you look at the stud drilling.  |Perhaps a different person took charge?  The whole set might be a right off.  When I looked at one of the steam chests, I thought - ahh re drill and blank the old positions until I turned it over.  Somebody had already blanked and filled old stud holes.   

[davewoo]

Hi Phil
A couple of things from running a Simplex to the original design for many years, the pump as designed I found to be a bit over the top, closing the bypass could definitely be felt to be putting the engine under a heavy load, and it filled the boiler in a very short time. I took mine off and have relied on a single injector, which has been ok but has caused some anxiety on very hot days! The pump as designesd is double acting, if you already have a machined pump perhaps you could convert it to single acting and if it still pumps too much sleeve the bore down a bit. My engine does go very well even though it is now very worn and due a rebuild, but has always steamed fine for a hour or so and then the smokebox fills with ash and needs clearing out, once this is done it goes fine again, this is when public running and working hard. I know there have been several posts on various sites about rectifying this, but I've just lived with it. Apart from that Simplex seems a tough old design capable of really hard work.
I've had many happy hours with mine, I'm sure you will too, but don't neglect Rob Roy I absolutely loved running mine, now waiting for a new boiler.
Dave

[simon6200]

I’ve also been running a Simplex on a single injector for over 10 years on public running days. I have water in the riding truck as the side tanks quickly get too hot. I fill them for added weight though. Great loco.

[Neale]

Our club loco is a Simplex. I would also comment on the axle pump - it's definitely too high a capacity! Gets difficult to adjust the bypass to get a sensible rate of feed and making it single-acting makes sense. We also have problems with sticking clack valves. That's another issue but it does raise the point that the pump is a bit of a nightmare to remove for maintenance. It would be easy if you could remove the frame stretcher underneath it - but one of the stretcher fixing screws each side is behind a wheel. On ours, it is just possible to waggle a spanner around the stretcher to remove the feed pipes. Otherwise it would be boiler off or drop the wheels... A bit of redesign around this area would make sense.

[philh1aa]

Great comments from all. At least converting the pump to single acting sounds the way to go and is probably quite straightforward. It saves time and wasted material because the pump looks like it has been quite nicely made.

I am also aware of the maintenance issue with inaccessible fixings. Perhaps use a much longer stretcher (lengthwise) with accessible fixings in front of the driving wheel?

I also plan to add brakes (cosmetic) on 4 wheels and cylinder drain cocks.

How about needle roller bearings versus plain cast iron axleboxes. Is it worth the extra work because the current ones appear to be nicely machined and bored?

Oh another cosmetic/ practical change is to make the buffer beams a bit wider - perhaps 10 1/4" wide. When I look at the end view of the engine, it almost looks like the buffer beams are 'just' too short because the cylinders stick out a bit. That would also allow for slightly wider tanks and or lead as Simon seems to suggest.

Phil H

[davewoo]

I've got oilite bushes in my simplex axleboxes which are milled from mild steel bar running on plain mild steel axles, which was a poor choice as the oilites in the trailing axleboxes have picked up ash made it into a fine grinding paste and worn themselves and the axle to an amazing extent ( still goes though!). The material choices were not made through scientific experiment or design knowledge but what could be found in the scrap pile at work as I was skint with two small kids during construction. John Baguley has experimented with needle rollers in axleboxes, you can find it on his excellent website under the "Helen Longish" build. If the cast iron axleboxes you have are ok I'd use them as cast iron seems to wear exceptionally well for axleboxes, my friends Springbok has run many miles with C.I axleboxes on ordinary mild steel axles with no apparent wear.I think you would have to be very careful to keep ash and grit away from needle rollers, possibly cannon axleboxes if you don't mind the extra work.
Dave

[ettingtonliam]

If the cast iron axleboxes and their axles look to be well made, then I'd go with them. Fitting needle rollers aren't worth the trouble IMHO.

[philh1aa]

Ok, thanks you very much for the additional comments. I will try to use the iron axleboxes provided they are the same in pairs and or correctable.

I put all the axles between centres to measure the wheel run outs etc. The worst wheel was 0.020" smaller than its partner on the same axle combined with a runout of 0.030". The high runout was due to a casting defect for about 1/3 of its periphery. The other wheels were not as bad but not far off.
Correcting the worst wheel would need a steel tyre rather than a skim so I lay down in a dark room for a while and remembered how fortunate I am to have a scrap yard about 1 mile away.

By the way, I am not proud of my inspection process when I bought this chassis but it is a harsh lesson. I guess that you are lucky sometimes but not all the time?

Phil H

[philh1aa]

The cleaned up frames for my new Simplex.

[philh1aa]

[philh1aa]

The plates had been nicely sheared so they could be mounted directly onto the table top.

[philh1aa]

This is one of the damaged cylinders. The poorly machined ports could have been corrected with a new, bronze port face but add the stud drilling issues and I think it starts to get easier to buy a new rectangular block of cast iron and start from scratch.

[philh1aa]

And the damaged wheel. Once the tyre has been defined properly on the inside edge of the rim plus the runout and casting defects machined away, I don't think there would be much rim left over. This is the worst wheel but the others are not brilliant. New wheels!

[flyingfox]

Greetings Phil, you seem to be a busy bee indeed. Although I have never built a Simplex, I have driven many, and always found them to be good performers.

looking at the frames, had you not considered a pair of laser cut frames, which do save a lot of work.

The cylinder could have those two poorly drilled holes plugged, covered by your new Bronze port face, and a new pair of holes redrilled in a slightly different position.

The wheel could be fitted with new steel rims, shrunk on, which would save a lot of work.

Regards

Brian B

[mbrown]

I agree with Brian re the cylinders. Plug the extraneous holes (even use filler as they are not subject to pressure) then make a new steamchest and cover with the holes in the right place, or even plug the misplaced holes through the steam chest, re-drill them and use them to mark the position of new holes in the cylinder block.

Assuming the bores are OK, this would be a fraction of the work involved in machining new cylinder blocks, milling ports etc.

I guess it depends if you are a perfectionist or just want a working loco!

Malcolm.

[philh1aa]

Brian/ Malcolm,

Yes I did consider laser cut frames but Simplex looks, well erm simple. Yes it was a bit of fun on my small milling machine but the result was good. Plus, my dad who is no longer with us had the frame steel sheared for Simplex so it is nice to make use of it.

Perfectionist? I have absolutely no problem working with these old parts if they can be made good. Infact, it is nice to reuse or recycle parts but I wouldn't be happy leaving say the cylinder cover holes looking uneven as they are. Yes, I am sure they would be functional but there are limits.

However, now that two of you chaps have encouraged plugging and redrilling, I had another look and this is my conclusion after careful checks and measurements;

Every hole on 3 ends out of 4 for the cylinder covers need to be plugged and redrilled using new covers obviously. For example, one end has 10 holes instead of 12 and the future cylinder drain cocks have not been 'missed'

Every single steam chest stud hole would need to be plugged and redrilled. Some of them look ok in that picture but they are well off when the outside of the cylinder has been cleaned up.

[philh1aa]

Oh, what would you guys recommend for plugging if I go down that route. I obviously don't want corrosion problems or something else nasty. Would brass do the job?

[mbrown]

It's hard to judge from the photos how far out the holes are. Personally, if the holes in the ends are reasonably accurate in relation to the bore, I would stick with 10 studs and not bother with making it 12. 10 studs will be more than enough to hold the end covers.

For plugging the ones that can't be rescued, I think you have several options. If the portface is nicely smooth and flat, it would be good to keep it that way. You could try a filler such as Isopon or JB Weld - push it firmly into the holes and allow it to be a little bit proud of the surface, then bring it down flat and true to the portface by rubbing it on fine emery paper rested on a flat surface. I reckon that would be fine so long as the new holes were not too close to the filled ones.

As the rogue holes appear to be threaded, an alternative would be to use short lengths of screwed rod - I would use brass as it is softer than the iron - leaving them just proud of the surface, then smooth them down to the level of the portface starting with very very careful filing with a smooth file, and finishing dead flat with the same emery cloth on a flat surface technique. If you put a spot of high strength loctite on the threaded pieces when screwing them in, they would be there permanently and won't move when filing them down. The brass would also allow you to drill a hole part in the bock and part in the brass stud and then thread it, if that was needed to get the positions right.

Worth a go, anyway.

Good luck

Malcolm

[nonort]

If I were to be starting now I would certainly be fitting steel tyres shrunk on. My professional experience has proven that anaerobic adhesives are great for the jobs that they were intended for. The atmosphere that a steam engine works in are not very conducive to a long service life. I have fitted tyres to several engines using EN8 these after several hundred miles are showing no signs of ware. They have all been profiled to the standard not the LBSC profile.
All the best

[philh1aa]

Malcolm,

Thanks for the input regarding the brass and JB weld etc. I agree that the photo is bad for showing the true horror. If I used the current studs for the covers, I would have 1 cover with 12 fixings, 2 with 11 and 1 with 10. The ends closest to the front buffer beam at least need to be the same on both sides. I'd agree that the covers facing the valve gear etc are mainly hidden, so you would need to be looking very carefully to spot the problems.

The other thing I haven't added till now is that 2 of the port drillings start to enter the cylinders as much as 1/4" from the end.

I will have one more survey then take a decision because the survey time and trying to make a bad job work also takes quite a lot of time.

Nonort, thanks regarding the information on the wheels. I had a quick look on M Machine and there is a conveniently sized thick walled tube available.
But again, would you really do just one wheel when all wheels have their faults? Repairing them might be just as bad as machining new wheels because none of the wheels have the correct tread form - so they all need machining. Like the cylinders, one more careful survey and Ill make a decision.

Phil h