99 3462 Build diary

[mbrown]

After completing my fabricated cylinders (see the separate thread) I said I would start a new thread for the loco build itself. Although I have already introduced the project, this new thread is likely to run for some time, so maybe a more detailed description is in order at this stage.

All my models are built for 2.5" gauge and represent 2' gauge prototypes. The reason for this is largely accidental - I started model engineering at the age of 13 when someone gave me drawings for LBSC's Southern Maid in 2.5"g, and eventually a model emerged, rather unlike Southern Maid, which managed to stagger up and down a short end to end track. Then came university, various jobs and further training until, at the end of the 1970s, I at last had a house and enough money to resume model engineering. I only had a very small lathe (a Centrix Micro - about the size of an Adept - later upgraded to a 2.5" EW) but I did have a spare set of 2.5" g cylinders and a strong enthusiasm for the narrow gauge, so a loco duly took shape and went very well indeed. Two others followed over the years, culminating in my Burma Mines loco in the avatar picture, completed in 2018.

My new project is a 600mm gauge 0-8-0 built in 1934 by Orenstein and Koppel for the Mecklenburg Pommersche Schmalspurbahn. It was one of three, but two were sent to the USSR after the War as reparations and promptly disappeared. The survivor became 99 3462 of the Deutsche Reichsbahn (E Germany) and remained in service until the line closed in 1969. She was then bought for possible use on the Vale of Rheidol and was stored for some years at Boston Lodge on the Ffestiniog. But eventually, she returned to Germany as part of the collection of Herr Walter Seidensticker who financed a major rebuild for service, initially, on the Kleinbahn Muhlenstroth at Gutersloh. Indeed, she is back there now, having had about 10 years on the German-Polish border at the Waldeisenbahn Muskau where she could get a decent run on a very fine railway. Apparently the boiler is now near the end of its ticket and so her future is uncertain. I visited the WEM last June to see her and take measurements and photos from which I am attempting to build the model.

Anyway, here she is in DR times.

99 3462 (3) by malcolm brown, on Flickr

The rebuild simplified a lot of the pipework and valves fitted by the DR, and a later overhaul certainly changed some of the boiler fittings, so I have an interesting task ahead to decide which era to model.... Here she is outside the shed at Weiswasser on the WEM, decked out for a special occasion.

ok_12518_60 by malcolm brown, on Flickr


That is probably enough introduction.

Now that the rather complicated cylinders have been completed, the next stages of construction are pretty conventional. I got to grips with 2D CAD over Christmas and have already received the frames and many other components from Malcolm High at Model Engineer's Laser, with another batch of drawings about to be sent off to him. This is the first time I have used CAD and laser cutting on a model and, having decried it as "cheating" in the days when I couldn't hack it myself, I am definitely coming round to the idea!

The first serious work, however, has been on the wheels. Last weekend, I did the tender wheels from some old disc wheel castings I had lying around for years. Unfortunately, one of the flanges has been fettled very aggressively, meaning that the overall diameter had to be a bit under size. But the wheels on the prototype are turned regularly, as the photo below proves, and will by now be somewhat down on the designed diameter, so I am content with "turned" wheels!

1509215_480148415423528_1924396876_n by malcolm brown, on Flickr

The small hole in the disc wheel is interesting. It may be there to stop the wheel "ringing", which is sometimes done on disc wheels, but I suspect it may have been done to enable a sling to be used to hoist the wheel set onto the lathe (etc.) when necessary. Anyway, I put holes in mine. Here they are, with one set mounted on a temporary axle.

IMG_20200503_180343 by malcolm brown, on Flickr

Underneath is the only drawing I have been able to find of 99 3462. I blew it up on a copier to A3 size from a small version in a book. It is not reliable as the dimensions include one of 600mm (gauge) and one of 1800mm (width over cab and tender) but the latter is definitely not three times the former when one puts a rule to the page. So useless for measuring off it - which is bad practice anyway - but it does give a general idea of shapes and proportions.

The wheel castings only had a very shallow recess on back and front faces. Real disc wheels are quite "thin" between the rim and the boss, so I have turned a much deeper recess either side. They are still over scale thickness but look much better.


For the driving wheels, I found some slabs cut from steel bar which, again, have been under the workbench for many years, I like steel for driving wheels, so these are being turned up to suit. By close of play this weekend, I had faced both sides and turned up the front face on three wheels, with five more to go followed by the treads and rear faces. As with the tender wheels, I am recessing both sides quite deeply. It is making a very large pile of steel swarf....

On the prototype, all the wheels are hidden from view. But the driving wheels have balance weights and appear to have holes through the web of the disc. When I visited, the loco was only moved over a pit at the very end of the day when the staff were keen to get home, so my time down there was limited and I didn't get any decent photos or dimensions. The shot below, from the internet, is the best view of the wheels I have. It also shows how the frames are plated over at footplate level so the wheels are invisible from on top, Nevertheless, I intend to add balance weights and some sort of holes in the web. Then at least I will know it is more or less right....

934742_651518544953180_2769740261498220148_n (1) by malcolm brown, on Flickr


Here is where the driving wheels are up to - three done on the front face, one in the lathe, and four blanks lined up behind.

IMG_20200503_165712 by malcolm brown, on Flickr


As I said, nothing very exciting at this stage of construction, but there are some interesting features yet to come. More another day....

Malcolm

[steamer5]

Hi Malcolm,
This is going to be a fun build if the cylinders are anything to go by!

On the drawing front if you can save your drawing as a PDF you should be able to import it into your drawing program, I could in Draftsite, from there you can then, using the right command, select a known dimension & the program remembers what it is & you can use that to find other dimensions. You need to do a vertical & horizontal dimension as the coping can stretch the drawing. My youngest son gave me a how to over the internet on doing this, sorry I would have to retrain so can’t give you a real how too. If you don’t already know this then I’m sure somebody here will be able to help you out. If not let me know & I’ll get the info for you.

Cheers Kerrin

[rwilliams]

Another recent trick I've found that works - in part to deal with proportionally incorrect drawings uses MS Word - or similar word processing application. Basic manipulation of a drawing (JPG or similar) can be one in one of the menus there.
I recently needed to 'scale' some photos of a loco for model railway purposes, as I had a nice side elevation (works photo) and a couple of known dimensions.

So..

1) Import photo into Word - I found it best to set the page to landscape format first
2) Crop the photo to the known dimension - eg 'length over buffers' or 'Rail to cab roof'
3) Determine the scale dimension of the known length
4) Set the image dimension to the scaled size. You may have to click the button that delinks the x/y axis if you want to adjust one more axis more than the other.
5) Save your work!

It's not going to generate super accurate works drawings for you, but you'll end up with a proportionally correct picture which may be of some use.

[mbrown]

Thanks both.

My CAD skills are about as basic as they come - as rwilliams knows perfectly well as he taught me what I know in about 3 hours flat! I may try to extend my skills base sometime, but I need to establish basic competence first.

I took a lot of dimensions from the loco itself (and ones I missed, like the wheels, are not critical) and I also have hundreds of photos which give details, like rivet positions, that you don't get on a GA. From these, I can position everything that matters - and extrapolate positions of other parts like frame stretchers.

I built LYN from the Baldwin Erecting Diagram which was basically an outline and a few key dimensions. It's only on the Burma Mines loco that I had the luxury of a comprehensive GA.

Compared to others' work, this is more about muddling through than real engineering, but it can still be fun!

Malcolm

[mbrown]

Since my last post I have been busy trying to finish off the wheels, but work came to a stand this lunchtime and it might be a while before I start again, so here's an update to keep the thread active....

All eight wheels are now turned from the steel blanks. I don't know what sort of steel it is - the blanks came from Whistons many years ago and all I remember is that they aren't EN1 or EN8... whatever they are they were pretty tough to turn. The 75mm dia blanks were roughly 3/4" thick whereas the wheels are 9/16" over the boss and 1/2" thick over the treads, with the web recessed both sides to be about 3/16" thick, so that was quite a bit of work. Here is a wheel having the front face recessed using a home made HSS tool.

IMG-20200508-WA0000 by malcolm brown, on Flickr

In the first operation, with the blank in the church, the face was cut back to leave the boss standing proud, the bore was drilled and reamed and the tread was roughed out up to the chuck jaws. Then the front face recessed by about 3/16". The wheel was then held by the rough-turned tread while the back was also recessed. Then in the third operation, the wheel was mounted on a spigot in the usual way and the tread turned. Here are all eight done.

IMG_20200510_121555 by malcolm brown, on Flickr

So how to do the balance weights? I thought of doing them from sheet but I didn't have any thick enough. However I did have two further billets of steel, also from Whistons, which at 55mm dia were just the right OD. here they are after facing and drilling through 1/2".

IMG_20200510_121506 by malcolm brown, on Flickr


The idea is to bore them out to the diameter of the wheel boss, part off discs of the right thickness and cut each into segments making three sectors out of each disc. If I can get three discs out of each blank I will have 18 balance weights - two per wheel and two spares. Then they will be screwed onto the wheels, probably bedded in a layer of Araldite to keep them firm and form a little fillet where needed.


However, at this stage I heard an odd clicking from the drive on the Myford and a few seconds later the main motor-to-countershaft belt parted. No idea how old it is - it was on the lathe when I got it 13 years ago - and because of the belt cover I confess I hadn't examined it for ages.

So the weights will have to wait, so to speak.... I have ordered a new belt but in the current circumstances it may take a while to arrive. I shall have to think what else I can make that doesn't require the lathe. But, to be honest, I am finding working from home during lockdown, managing the normal work as well as the crisis response, is pretty exhausting and it may be a good idea to spend what is left of the weekend with a book and one of Jim's soothing ales....

Anyway, my swarf bin is full - a lot of material came off those wheels!

IMG_20200510_124515 by malcolm brown, on Flickr

Best wishes all.

Malcolm

[timb]

Good work Malcolm, not a bad idea to have a break! After all...
Confucious say
"When it is obvious that the goals cannot be reached, don't adjust the goals, adjust the action steps."

Enjoy the beer!

Tim

[mbrown]

The replacement primary drive belt for the ML7 arrived on Thursday which, as I only ordered it on Sunday night, is excellent service. Unfortunately, though, it's not right - turns out it's for an ML7R which is the same as a Super 7 in most respects. Labelling a de-tuned Super 7 as an ML7R was about the daftest thing Myfords ever did, as the parts are almost all incompatible with the ML7. Not sure if it was my fault for ordering on-line without looking closely enough, or if they sent the wrong part, but I have ordered another with great care to see that it is as specified for an ML7.

Nevertheless, although the one received is a bit too short, it is just about OK and enabled me to use the lathe this weekend to finish off the balance weights for the coupled wheels.

I ended the last post with the two steel blanks faced up. I then drilled them 1/2" and mounted them on a bolt supported by a center so that I could cut deep grooves to make three discs out of each blank. I couldn't do this in the chuck as the jaws fouled the parting tool. By taking it gently, I was able to turn two deep grooves in each, leaving the core diameter at fractionally under 1".


IMG_20200516_153858 by malcolm brown, on Flickr

One side of each disc was chamfered so that each weight would sit nicely in the recessed face of the wheel. Then lines were scribed on the face at 120 degrees (I used the chuck jaws as a guide) to mark out the three weights per disc. I used a slitting saw in the mill to cut part way down to the core.

IMG_20200516_170157 by malcolm brown, on Flickr

Each blank then went back in the lathe and was bored out until the centre was 1" diameter to match the boss on the centre of the wheels. As the core diameter under each groove was a little under 1", each disc just dropped off as the boring tool got to it, with each segment part-separated.

IMG_20200516_175851 by malcolm brown, on Flickr

While each was still a disc, I used the rotary table to drill the fixing holes so that they all matched up.

IMG_20200516_182440 by malcolm brown, on Flickr

It was then straightforward to separate each segment with a hacksaw as the cut had been started in line with the slitting saw. A few stokes with a file smoothed the ends and took the sharp edges off the corners. One segment was tapped 6 BA and the other used to drill the wheel before being deeply countersunk for the fixing screws. Here is the first wheel - back and front:

IMG_20200516_210130 by malcolm brown, on Flickr

IMG_20200516_210145 by malcolm brown, on Flickr

The screws need to be countersunk a little deeper, and when the weights have been set in a bit of Araldite, they will be turned on the faces to remove the protruding bits of the screws. I only managed to assemble one tonight - with luck, I will get all eight done tomorrow

Best wishes all.

Malcolm

[mbrown]

A few hours in the workshop today saw the driving and coupled wheels finished. The balance weight segments were screwed in place permanently with a smear of Araldite to bed into and to give a tiny fillet to resemble a casting. Then they were faced back to the correct thickness at which point the screw heads and points disappeared. The driving wheels have slightly thicker balance weights than the coupled wheels, as on the real machine.

The prototype clearly has holes through the web of the wheel but none of my photos show them properly. My notes, from the short time I was able to go underneath, just say "two holes", and the one photo I have suggests that they come quite close to the balance weights. I have a slight suspicion that they are actually ovals, but reproducing that was a step too far for me. So I put them in at 90 degrees to the balance weight and I think they look OK.

Here is one pair after a coat of primer to prevent rusting - it will be some time before the rest of the loco is built around them.... The other six were waiting to have excess paint taken off the tyres.

As with the cylinders, I have made a lot of swarf, and it took a lot longer than if I had had castings made. But eight wheels in tough steel, close to the prototype in style, is a good outcome, even though they won't be seen when it is finished.



IMG_20200517_201825 by malcolm brown, on Flickr


I am expecting a parcel of laser cut parts from Malcolm High later this week, so I will then have to decide what to make next. Possibly the tender frames, stretchers, buffer beams etc.

After next weekend I have several days' leave. No volunteering on the Talyllyn Railway, no chance of visiting the grandchildren... just workshop (and slobbing out...) time!

Malcolm

[mbrown]

Here's a question about leaf springs as I am starting to think about how to do them on 99 3462.

The prototype springs are outside the frame and very visible. They have surprisingly few leaves. This is the tender spring - the loco ones are bigger but similar -- and there are four leaves, each 1 cm think. That scales to about 18g or 1.2 mm for my model.

DSC00447 by malcolm brown, on Flickr

I don't much like Tufnol springs - the ones on Lyn have started to lose their camber. And, if possible, I would like to use the correct number of leaves of the right thickness - although I appreciate this might not be possible.

I have seen examples where people have cut out the centre of the leaves to make a more flexible spring. But I can't find any guide to how much to cut out or how to calculate the flexibility. The only formulae I have seen require one to know the weight of the loco, and I won't know that for a long time.

Does anyone have a rule of thumb for leaf springs of this kind?

I have also heard of people using bronze strip successfully. Again, does anyone have any direct experience they could share?

Many thanks

Malcolm

[miketaylor]

Hi Malcolm,

As no one else seems to have responded I will have a go. Theoretical rather than practical experience I’m afraid.

Firstly, you haven’t given either the length or the width of the springs. Both of these contribute to the spring characteristics.

Secondly, you can’t reasonably try to design a spring without knowing what load it has to carry.

Thirdly you will have to decide what deflection you want to achieve under a given load. Perhaps something like 3 or 5 mm under the nominal wheel loading?

That said, for a given set of geometrical characteristics/dimensions, the strength/rate of a spring will be governed by the modulus of elasticity (Young’s Modulus) of the material from which it is made.

Steel has a YM of around 200 Gpa
Stainless Steel 180 GPa
Bronzes 96 -120 Gpa (Aluminium Bronze 120; Phosphor Bronze 116)
Aluminium and aluminium alloys around 70 Gpa
Titanium alloys 105-120 GPA
Copper around 120 Gpa
Brasses 100-125 Gpa
Monel and Nickel around 170 Gpa
Nickel Silver around 125 Gpa

You will see from this that for a given spring geometry you can have quite a wide variation in spring characteristics simply by choice of materials.

Once you start messing about adjusting the strength of each leaf by machining out the centre the calculation of strength/defection gets more complicated and, I suspect, less accurate.

You will presumably want to maintain the solid appearance of the upper surface of the top leaf so you will only be able to reduce that leaf by machining a groove in the underside, perhaps half the width by half the thickness.

Fortunately, your springs are beautifuly simple and you can easily set out to design on a suck it and see basis.

Make a sample spring out of steel, right number of leaves at the right size. Load it and check the deflection. You don’t have to bother about curvature. This sample can just be made from flat strips.

Depending on the results of the first test you can modify the sample spring by machining out centres. You will be looking for a final spring which is either satisfactory in itself, or which will be satisfactory when it is made in an alternative material and its rate increased in inverse proportion to the Yms of the materials used.

For example, if you manage to create an acceptable looking steel spring which only deflects half the required amount then a similar spring made in bronze should work fine.

Hope this helps

Mike

[mbrown]

Thanks Mike,

I find that much more helpful than the even more theoretical articles by Tubal Cain and others on the subject. Although I can't yet work out the finished weight of the model, I have several models of around the same size from which I might be able to extrapolate a rough weight. I like your approach of making a trial spring and then comparing it with what is needed - I can get my head around that!

I will report on my findings when I have had a chance to try this out!

I do recall someone else on this forum who made beautiful springs of spring steel strip with "hollowed out" centres - if he is watching, maybe he could explain how he did the calculations or whether it was a similar case of practical experiment

Thanks again - much appreciated.

Malcolm

[don9f]

Hi Malcolm, “44767” described hollowed out springs for his Class 3 tank.....try page 10 of his thread.

Don

[mbrown]

Many thanks Don - that rings a bell. I will see if I can track it down.

Malcolm

[mbrown]

A bit more progress this weekend - nothing spectacular. I have made a start on the loco front and tender rear buffer beams. The main plates were my first venture into CAD and came out nicely when sent to MEL. The doubler plates are straight forward and the angle on the top of the loco front beam was cut from square steel tube. The latter was milled down a little on all four sides to get the thickness right and sharpen the angles, then I used a slitting saw in the mill to cut the angles at the correct depth. By leaving the square tube uncut at each end, it was possible to do this with very little distortion and the last bits were cut through with a junior hacksaw.

IMG_20200524_193919 by malcolm brown, on Flickr

The holes were all drilled in the mill using the simple DROs I fitted to each axis a while back to get the spacings right. The bits are fixed with temporary screws as the final rivets or screws will also connect to angles and stays on the other side - the construction between the frames is quite complex. Some of them will be 2 mm rivets and others 8 BA roundheaded screws without slots which are almost exactly the same size as the rivets.

Next jobs are likely to be all the bits that bolt onto the outside of the frames - spring hanger brackets, horn cheeks, equaliser pivots..... on this loco, all the bits are on the outside, unlike most UK practice.


Malcolm

[mbrown]

A couple of days off from the "virtual office" has allowed some time to make progress on the buffer beams. The deep beams illustrated earlier are at the front of the loco and rear of the tender - between the loco and tender the beams are shallower with a buffer between them and the drawbar running beneath the beams plus safety chains.

DSC00487 by malcolm brown, on Flickr

The buffer has a fairly thick face, curved horizontally and with the ends "domed". I puzzled for a while about how to get the curve on such thick material (about 3/16") but then almost literally stumbled over an answer... Among the bits and bobs "liberated" from various scrap bins over the years, I had a short length of 4.5" steel pipe with walls about 1/4" thick. I originally had it earmarked as a smokebox, but it was useless for such purposes as someone had made an erratic saw cut through about a third of the diameter. It had lain under the workbench for some years but when I saw it an idea formed.... thanks to the saw cut already there, a couple more simple cuts gave me a piece big enough for the buffer head. First, though I chucked the tube and bored it out to 3/16" thick part way so it was the correct thickness. I didn't photograph this process, but here's the tube after the segment had been cut out.

IMG_20200528_122339 by malcolm brown, on Flickr

Careful filing gave me the domed effect I was after. The guide through which the buffer shank runs was easily fabricated, as was the housing behind the beam for the spring. This latter piece is something I had to guess at because on the prototype it is hidden behind a horizontal stretcher, but I worked out that this was the likely arrangement from the position of the bolt heads on the buffer beam and the relatively few alternatives I could imagine. Here are all the bits before silver soldering.

IMG_20200528_132637 by malcolm brown, on Flickr

And finally, here it is assembled. The loco beam has a rubbing plate to bear against the buffer head.

IMG_20200528_164701 by malcolm brown, on Flickr

IMG_20200528_164733 by malcolm brown, on Flickr

There are still a fair number of angles to fit to the beams, and there are horizontal stays at various points which bind together the frames and the beams. That will have to wait until I have made more progress with the frames. But meanwhile, I have a spring buffer to play with (I call it an "executive toy"!).

Best wishes

Malcolm

[don9f]

Hi Malcolm, excellent....

That arrangement of the safety chains could have been “pinched” for use on the BR Standards!

Cheers Don

[mbrown]

I am waiting for materials for things like spring hangers which need to go on the tender frames before I assemble them to the buffer beams and stretchers, so made some progress today with some of the smaller details. The photo here, taken from the pit under the loco, shows the bracket which carries the drawbar. This is the one on the loco and the shot is looking back under the rear buffer beam to the front of the tender. The other end of the drawbar is carried in an identical bracket on the tender.


DSC00508 by malcolm brown, on Flickr

Looking at the shape of the bracket, and comparing it to a length of rather heavy 3/4" (nominal) square steel tubing, I realised how I could make the main U shaped part. Here is a length of the tubing, roughly faced off, and with two slots milled down opposite sides - these will locate the ribs.

IMG_20200530_161141 by malcolm brown, on Flickr

This was then split in two, holes drilled and bushes turned, and small bits of scrap wedged in place to be the ribs - the whole lot resting on a base plate. Here is one of them after silver soldering. This one floated about on the flux so it is a bit skew whiff - but I left plenty of extra material on the base and it all cleaned up OK.

IMG_20200530_190837 by malcolm brown, on Flickr

After the usual age spent cleaning up, here they are - along with today's other products, the brackets which carry the safety chains. These were simply bits of 12 mm steel angle, milled down to thin them out, soldered to each end of a length of flat material. The latter was then cut down, drilled and shaped. The light isn't flattering o the finish - a coat of matt primer would show that they are pretty smooth.

IMG_20200530_201031 by malcolm brown, on Flickr

So I have one drawbar socket and two safety chain brackets for the tender and ditto for the loco - I must remember where I put the ones for the loco as they won't be needed for some time....

Malcolm

[mbrown]

A few more small fabrications for the tender completed this weekend - this time, the spring hanger pockets as seen below. There are eight on the tender and another eight on the loco, so I set out to make 16.


DSC00503 by malcolm brown, on Flickr



I started with two lengths of 10 mm square BMS which were milled down the right section and then a slot put down each length.


IMG_20200607_131906 by malcolm brown, on Flickr


These were then run under a slitting saw to part off 16 pieces each 5/16" long. Each was then drilled with a simple jig and mounted on a piece of 3 mm x 12 mm strip as the backplate. Unfortunately, I ran out of the 3 mm strip so juts concentrated on finishing the tender sockets - most of the bits for the ones on the loco are to hand. Here are four screwed together temporarily for silver soldering and another four already done.


IMG_20200607_161257 by malcolm brown, on Flickr

Then they were all cleaned up, fixing holes drilled with another small jig and are ready for fitting when I have done some other bits and bobs.

IMG_20200607_184724 by malcolm brown, on Flickr

The backplates may need thinning down a wee bit, but that can wait until I see how they line up with the springs.

None of this is terribly exciting but it is all progress (albeit slow....)

Malcolm

[springcrocus]

Jun 7, 2020 18:59:12 GMT mbrown said:

... None of this is terribly exciting ....

Malcolm

I disagree, making anything is exciting. It is only an armchair- or cheque-book-engineer who may not understand the pleasure of making something from nothing. If you doubt me, just look at procreation. 

Regards, Steve

[mbrown]

Hmm.... model engineering is probably cheaper in the long run. And certainly these days I spend longer in the workshop than in the boudoir... MUCH longer!

Malcolm