Hi and Andrew Barclay model engine

[mbrown]

I think it was Chris Rayward.

His LNWR wheels are complex - involving a basic casting and then two laser cut discs fitted either side of the casting so that the H shaped spokes are, in effect, made up of three parts.

They look great but it must involve a lot of work..

Malcolm

[don9f]

Yes....here it is and if you zoom in on the photo of the Coal Tank, you can see the wheels as described above by ettingtonliam and Malcolm.

Don

[Kevan]

Jun 22, 2020 19:18:06 GMT don9f said:

Yes....here it is and if you zoom in on the photo of the Coal Tank, you can see the wheels as described above by ettingtonliam and Malcolm.

Don

Yes that is a similar pattern. I can’t see how this was done with sand casting though.

On the Rob Roy there has been less progress than I hoped. I started on brake gear but ran into problems. First is that the holes in the frame drawing are tapping for 2BA not 4BA as described in the book. Second issue is that the rear brake hanger will foul the ash pan drop pin despite the holes in the frames matching the drawing in the book!

This is the set up for cutting the clearance slot in the back of the shoe


Not great as the iron is nasty with hard bits.

I realised I needed to re mount the cylinders to accurately determine clearances. So these went back on yesterday and some de-bodging is required. There were spacers between the cylinders and frames when I got it and putting it back that way looked like problems with the valve cross head fouling the axel box so I tried without the spacers which results in zero clearance between the left cross head and leading crank pin! Out came the callipers and it seems the left leading wheel is about 25 thou wider than the others! I thought I was done with the wheels but I suspect I need to pull them apart and thin that one down on the tyre and the boss.

A general issue is the previous builder has drilled all the suppposedly tapped holes in the frames and used nuts and bolts. I haven’t found anywhere yet where this will be an insurmountable problem but it makes some assembly fiddly and very tricky once the boiler is in.

Next issue is cross heads and slide bars. These were all a rattle fit including an 8BA nut and bolt holding the piton rod loosely in the cross head replacing that with a pin has locked the thing up quite badly. In the book it only mentions fixing the slide bars to the back covers nothing about how they should be fixed to the motion plates. The previous builder has brazed them on. There has been further bodging here as the top edges of the motion plates has been roughly machined off to get them below the line of the footplate. I am really not sure how to proceed with this as it seems the dimensions in the book don’t quite work and I am not sure how the slide bars are supposed to be fixed, any suggestions gratefully received!

Kevan🤔

[stevep]

The slide bars on my Rob Roy are secured at the rear cover, and sit in recesses in the motion plate. They are not fixed at that end.

As far as I remember, I built mine to the drawings, and had no problems, although I didn't fit brakes. The only exception were the steam chest dimensions, as the valve rod doesn't line up with the valve gear as drawn. (In the book, there are photos of engines with off-set connectors between the valve gear and valve rod). I think the off-set was 1/8", and I left my valve face 1/16" further from the bolting face, and put the valve rod through the steam chest 1/16" higher. The only drawback is that it makes the space between the steam chest covers a bit tight to get the pipework in.

[Kevan]

Steve

Thanks I pulled the slide bars off one of the motion brackets and that resolved some issues but highlighted others! All the bolt holes in the covers are a bit oversize which results in piston binding between the cylinder bore and the piston gland depending on how the cover is bolted up. I am just trying to figure a solution that does not require new back covers!

Kevan😟

[smallbrother]

Hi Kevan.

Been following this project as you seem to be picking up many problems that are similar to things i have got wrong myself.

Have to say I admire what you are doing. I would much sooner sort out my own mess (of which there is plenty!) than try and clear up someone else's!

Good luck with it all!

Pete.

[Kevan]

Pete

Thanks! This is a learning project for me and started out cheaper than buying castings and materials for a Rob Roy chassis. Money is being spent on tools and sundries like nuts bolts taps dies packing and gasket material not to mention chemicals cleaners and paint! These things will be used for other projects as well I guess!

I am also doing knowledge transfer from other activities to do things in a most un model engineering way! Today included wielding my 5 1/2” angle grinder for rough shaping the brake shoes from a ring cut from a scrap 4” pipe flange 😃 no time for photos today but will post some later in the week!

Kevan

[Kevan]

As promised here are brake blocks and hangers carved out of scrap with judicious use of 125mm angle grinder



I am now waiting for the Royal Mail to deliver some more material to make the rest of the brake gear.

Kevan

[Kevan]

A bit of an update and sad story! I have progressed the brake gear a fair bit with hangers pins links a la Barclay not Evans and this weekend completer the cross shaft. Sunday afternoon was spent not making the brake column. Well started to make it but set out wrong from the start. I had a suitable lump of brass that we had used for parallel turning tests setting up the lathe. So I started by using the parting tool I had in the tool holder to put grooves In to define the length. I then set about turning the taper with the top slide something I had never done before so it took a couple of tries to get the correct angle as the top slide handle kept hitting the tailstock! Quite pleased with myself I then embarked on an operation I should have done first, that is boring the hole down the middle ! As it was too long for the drill I moved the column into the 3 jaw holding by the spare end material on the bar and drilled in the full length of the drill. I then reversed the column in the chuck grabbing the other gash end but the drill sheared the bit between the gash end and the column which I had turned too narrow with the parting tool and befor I could stop the lathe the column slipped between the chuck jaws and hit the tool holder bending itself!

I should have quit at that point and started again but I knew I didn’t have enough time before I had to be home to make another from scratch. So with the vice and patent adjuster (also known as Glasgow Screwdriver in Edinburgh managed to get it straight, a job finished in the chuck lining it up with the centre. This allowed me to finish the drilling operation. I then thought I should try and take a very light cut to get rid of the scratches. Next stupid mistake was trying to do this without the centre so the tool dug in a bit. Try again with the centre but I couldn’t take enough off to fix the dig in and chatter marks, Emery paper didn’t manage either, however I parted it off and set to tap the bottom for the 2BA nut. 3 turns in and the bottom sheared off as there just wasn’t enough wall thickness as I had drilled through with a 3.5mm drill not 1/8” as intended so here is the last mortal remains of a 4” x 5/8” lump of brass and a Sunday afternoon:(

Kevan

[uuu]

Never buy a chainsaw!

Wilf

[Kevan]

Jul 27, 2020 18:22:39 GMT uuu said:

Never buy a chainsaw!

Wilf

I am actually quite OK with a chainsaw! I probably have more hours chopping fallen timber for firewood and slash and burn rhododendrons on a friend’s land up North than I have on my lathe🤣

[mbrown]

From the look of it, I doubt if that is irrecoverable. It may, of course, be worse than it looks, but I would be inclined to turn off the broken end, turn a new piece with a spigot to engage with the hole through the column and silver solder it in place. You can then turn its outside diameter before re-drilling to the correct size - and that will be easier if you have a small pilot hole through the new bit. Then you should be able to hold one end in a chuck with the other supported by a centre and (very gently!) turn down the diameter to get it true and smooth.

Frankly, the price of brass today, I would go to some lengths to rescue a bit this big!

Malcolm

[Kevan]

I did think about it however this bit of brass came from someone’s scrap bin and I am on the track of some more scrap 100mm brass billets that are bar ends from a CNC machine!

I should try doing it in the right order next time rather than be as gung-ho as last time! It’s a learning process and I learn by making errors.

Kevan

[Kevan]

So it has been a while, the Barclay had to take second place behind emptying my old workshop and store, selling my older Myford and generally trying to organise aspects of life.

Since last time I have acquired a boiler and the better part of another Rob Roy. The boiler is largely to Martin Evans’ design except for an extraordinarily large fire hole! I spoke to the club boiler tester and his view is test it to 2x pressure and see what happens! So I have started making blanking plates and plugs. Another variation I found is threads. The bottom gauge bush and washout bushes seem to be M6 and the studs for the dome and regulator M3. I rather hope the others are ME as I have now ordered taps and dies for these.



Today I had another crack at the brake standard. Sadly the promised bar ends turned out to be aluminium rather than brass or bronze apparently the brass had been used in the company since I was promised it. So I thought I would try the brake standard in aluminium as I have lots that cost nothing. This time a more considered order of operations has produced a better result. There are a few things I don’t get from the book though. The rod is called out as 1/8” but no mention of the thread. The nearest tap and die I have is 4ba which doesn’t form a complete thread any guess what it is supposed to be?

The next problem is finding 3/32” steel rod to make the handle. I have 1/16” and 1/8” neither will do and I can’t turn down the 1/8” I tried!

[stevep]

5 BA is very close to 1/8".

[JonL]

Looks like the sight glass is on the opposite side too.

An unusually square fire hole, I wonder if the "Comet Windows" issue will rear its ugly head?

[Kevan]

So it has been a while since I have posted here. The loco has been held up by a number of side projects including putting a DRO on the lathe and messing about with a boiler. Today I finished the brakes😃

The Martin Evans set up seemed a bit over complicated and puny compared to the set up on a Barclay so I have largely copied what was on the full scale loco with bigger shoes further down the wheels, no adjustment in the operating rods, split pins fixing the hangers to the frame mountings and end up with a prototypical rattly result when the brakes are off! The lack of adjustment in the rods has required a fair bit of remaking to take up variations in the brake block thickness and in hangers.

Next challenge is the drain cock operating bits! What is in the book collides with the reversing gear so trying to figure out some space and adjustments to allow both systems to clear each other🤔

[JonL]

I know its a minor detail at this stage but I like the painting of the wheels and rods. The whole thing is coming together nicely.

[Kevan]

Yes I probably did get a bit ahead of myself with the painting! At least one wheel needs taking off and more machining as there is insufficient clearance between the crank pins and cross heads. The previous builder fixed this by shims between the cylinder blocks and frames rather than by machining the wheels to all the same thickness! The problem is extracting the crankpin from the wheel as I loctited it in before I realised the clearance problem!

[Kevan]

Here’s a question. I need to make some links with bosses for the drain cock gear. The ones for the brakes I largely filed out of bar stock and they don’t really have a machined look.

Today I saw an Enterprise with links like this machined to visual perfection. Is there an order of operations in a lathe that will do a good job of these? I do have a vertical slide so can do limited milling operations.

Thanks for advice on this!