Adventures in kit and scratch-building.

[sej]

My PMs?

[ozzyo]

My PMs?

 

Hello Simon,

 

on the top line above the blue line that says RMweb, you have a black line that your RMweb name on it, the one that you can click for your content. If you look to the left there is an envelope. if you have any PMs. (personal messages) it should have a red envelope with the number of them showing.

 

OzzyO.

[sej]

 

Hello Simon,

 

on the top line above the blue line that says RMweb, you have a black line that your RMweb name on it, the one that you can click for your content. If you look to the left there is an envelope. if you have any PMs. (personal messages) it should have a red envelope with the number of them showing.

 

OzzyO.

Oh gosh! Thanks ever so much for directing me to the PM function and my profound apologies to those people who left messages and got no replies! I'll try and be alert to them from now on.

 

Simon

[sej]

Made a start on the Armstrong today while a blizzard raged outside.

I'm keeping track of how long I take by marking the timings on the instruction booklet as I go.

Page 1 includes the building of the ashpan with a sliding claw device that engages with the motor/gearbox. Also, various chassis stretchers. Everything is etched in beautifully thin, springy nickel-silver. There is an element of 3D jigsaw building involved and you do have to look carefully at the photos and work out how the tabs align. Also the fit of the parts is so good that care is needed when removing the parts from the fret so as not to distort the tabs. Removing the etching cusp ensures everything goes together sweetly. My "Hold and Fold" device helps to produce nice crisp 90' folds.

Here are the bits so far.

[3 link]

 

Hello Simon,

 

on the top line above the blue line that says RMweb, you have a black line that your RMweb name on it, the one that you can click for your content. If you look to the left there is an envelope. if you have any PMs. (personal messages) it should have a red envelope with the number of them showing.

 

OzzyO.

 

Yes Ozzyo,

 

Totally agree, have you looked in yours lately ? sent you a pm about 4 days ago .

 

ATB, Martyn.

[sej]

After the ashpan and some of the frame stretchers the instructions move on to the main chassis frames. Four hornguides are folded up and fitted and specific bearings (thin for the leading axle and standard for the trailing) slide in with barely a fettle. You do need to tap the guides for 14BA and it's a good idea to make sure you've got 14, 12, 8, and 6BA taps. Eileens do them!

You also need to think very carefully about the orientation and handedness of the components. The slot/tab and bolt style of construction helps you to check everything before you solder up. MOK are great at replying to any queries you might have, I emailed with a question about the wheels I'm using (there are different components for Slaters or AH) and received a helpful and friendly answer on the same day.

The balance beam compensation(?) system is lovely. You have to tap a small bush to 6BA and the easiest way I found to do this was to hold the bush in the collett of my powerdrill and carefully hand-tap with the tap held in a small drill (see picture).

The chassis goes together beautifully using slots and tabs and I found it to be completely square and accurate, (checking with my Master Chassis jig.) There is a fantastic set of castings for the motion bracket and side arms which needed to be soldered carefully and tapped to be bolted to the chassis, the most difficult part of the build so far, and really, a doddle. In fact the most arduous task is to file all the tabs off everything once you've soldered up, (which explains the masking tape preventing filings getting into the bearing surfaces.

14.5 hours so far!

[sej]

Here is the cleaned up chassis with the footplate strengthening brackets attached (top of p4 in the instruction booklet); it has a certain raffish Star Trek look to it!

[jazz]

Very nice watching a master builder at work here.

[sej]

Thanks Ken and a Happy New Year to everyone, particularly those at RMWeb for the continuing good job they do for us!

Since Christmas I've put together the front bogie of the Armstrong and as ever haven't been able to avoid the temptation of putting all of the wheels on prematurely to see what it looks like. It runs along beautifully. I spent plenty of time fettling the bearing surfaces of the bogie so that everything ticks along nicely. My father alerted me to series of articles in the "Model Engineer" magazine by a gentleman called Peter Rich. He describes the building of 5 inch gauge models of both Dean Armstrong and Single locomotives. There are plenty of excellent drawings and prototype details and his models look fantastic. He plays the bagpipes too!

Working inside valve gear next!

[buffalo]

That bogie looks wonderful, though what confuses me is how it works. Is it sprung or compensated? The photo you posted on the previous page shows part of the instructions and, as far as I can make out, it says "tags act as stops to assist beam from rocking", so it's not really clear whether they prevent the beam from rocking or just act as limit stops when it does rock.

 

Nick

[sej]

Hi Nick, the bogie is beam compensated with the wheels running in outside bearings. The tabs are limit stops as you suspected. Here's a picture of the bogie before the beams went in. They're basically thin rectangles that slide into the deep slot at either side in the centre and locate at either end in some more tabs. They also have the rest of the cosmetic bogie spring gear attached to them and are held in place by 10 BA bolts. I think I've got some more pictures somewhere...

[buffalo]

Thanks, much clearer now.

 

Nick

[Rob Pulham]

Lovely work Simon. I am really enjoying this one.

[sej]

Thankyou Rob, the kit is a joy to build!

I've reached the inside valve gear and managed a test fit of some of the bits. Since taking these photos I've used a brass wire brush in the mini-drill to polish stuff up, making sure I wear goggles as bits of the brush fly about the room. I find blu-tak very useful to hold fast some of the more fiddly bits as I screw them together. I've done quite a bit of filing and very careful drilling to get the eccentric sheaves fitting nicely around the crank webs (I've learnt the words, I hope I'm using them correctly; there's an excellent drawing in the July 2011 edition of Model Engineer.)

What I'm interested in is how much clearance to give them. There seems to be a lot of metal to metal surface contact with a great deal of friction to be overcome, but I'm not keen on too much slop. Any tips or advice would be very welcome!

[sej]

While I'm having a think about the valve-gear (I like to take time off to have a think...swimming is very good for it!) I've decided to crack on with the parallel project of building "Earl Cawdor." I made up the inside side-frames about two years ago. I'd been to Didcot and seen the frames of, I think, their KIng, and was impressed by how thin they were and the fact that they were able to flex as the loco negotiated curves.

So, I cut these frames, in response, out of unfeasibly thin brass. Nickel-silver would have been better as it doesn't kink so easily, as of course thin sheet brass at 7mm scale doesn't act in any way comparably to inches thick steel! Curses! They took me some time to fret out so I've decided to soldier on with them, strengthening them as much as is possible. Compared to the Armstrong kit, I've also made them too shallow, so can't fit hornblocks in without severing them twice on both sides. In go a couple of nice thick compensation beams instead. I've posed the result with the intended tender.

Now, back to the Armstrong's valve gear...

[sej]

Doesn't work get in the way of the important things in life? Still, we've had beautiful frosty weather to cycle through in the mornings and the evenings are gradually getting lighter. I helped load and unload the crush barriers for the St Albans Exhibition last weekend and very much enjoyed some excellent layouts. The show seemed well attended and there were lots of kids, which is encouraging. The organisers thoughtfully provide rather cool periscopes too!

 

Back to the inside valve gear of the Armstrong, I used a hand vice and mini-drill with a dental burr/grinder to open out the eccentrics to a touch over 10mm inside diameter, taking care to keep everything circular. I finished off by polishing with a cylindrical stone in the mini-drill and checked for circularity against a 10mm drill bit. All now revolves smoothly and the next job is to solder the axle into the crankshaft and remove the unwanted bits of axle.

 

I've also added an ash-pan to "Earl Cawdor" which has fleshed out the inner frames a bit.

[sej]

On to soldering the Armstrong's leading driving axle into the crankshaft. I got everything central and square using graph paper, wood blocks and blu-tack. I really like graph paper, everything's already squared and measured for you! (It does burn though....)

I tacked the axle in place with as much power as the soldering iron could muster and then brought out the big guns! The mini-blow torch is wonderfully exciting and very, very hot. The flux disappeared in milli-seconds and the 179' solder with 2% silver nipped into the joints. Then a clean up with a steel brush in the mini-drill and a wee bit of fire fighting and all is set to remove the unwanted bits of axle with the piercing saw...

[3 link]

Hi Simon,

 

Thanks once again for an enjoyable episode, is there a method you use or are there instructions included as to the placing of the crank webs on the axle, I just wondered if it's an exact science with this kit.

 

ATB, Martyn.

[sej]

Thankyou Martyn, the instructions say that you should "centre the crankshaft accurately on the axle" and as I am a bit obsessive about these things I used the graph paper. However hard I try to mark out measurements I always seem to have to make adjustments after the event and there didn't seem to be any second chances with this one! The kit is so well designed that almost everything goes together beautifully first time and you do have to take care to make sure your concentration and understanding of the instructions matches the quality of design. Not too much whiskey then, particularly when wielding the blow-torch!

[sej]

Right, after a number of distractions, including a stand-up gig last night from which I'm pretty sure I'm now barred, (involved a kilt, a table and a mask of David Cameron...) I've got on with finishing the crankshaft. The instructions advise fitting the bearings and wheels before sawing away the unwanted axle portions, as pushing the wheels on afterwards could distort the crankshaft. I decided to support the webs with balsa wedges as I wanted to get at everything freely. I'll wedge it again when I come to put the wheels on for good. Although starting off with the razor saw I switched to a very fine blade in the coping saw for finer control. The result was suprisingly easy and very satisfying. A bit like magic in fact!

I'm not quite sure how to secure the wheels to the axles, they're a push fit with no mechanical attachment. Loctite? Super-glue? If any -one has some useful advice/ideas I'd very much appreciate it!

 

Next, putting everything back together and seeing if it all runs sweetly.

[N15class]

Hi

Could you not use loctite and then drill and pin. I am sure a nickel silver wire would hold things at the correct quartering.

[ozzyo]

Hello SEJ,

 

just check and see if theres a very slight taper on the axle just before the part where the bearing fits. It looks like there is in the above photos. If the axle has tapers you should not need any Loctite, but you will need something more sturdy than balsa wood, brass would be OK. The axle is looking good.

 

OzzyO.

[sej]

Hi OzzyO, very sharp-eyed of you, my trusty micrometer shows a taper on the axle; I might add a tiny dot of Loctite as belt and braces. I've just read your ideas on crank-pins in Sandy's thread, very helpful indeed! And I'll definately use some brass wedges when I fit the wheels. Cheers.

 

And thankyou too Peter, I hadn't considered the quartering; luckily, as they're outside framed wheels the quartering happens at the outside cranks which screw onto the squared ends of the axle. Very nice little machined ones are supplied with the kit.

[ozzyo]

Hello Simon,

 

you shouldn't need any Loctite on the taper to lock the wheels in place, the taper will do the job. If you use Loctite in this area you may get some in to the inside bearings (not that good).

 

When I did my first loco with outside cranks using Slater's wheels I turned up a pair of "pusher" bushes that would be a nice fit over the extended end of the axle and be long enough to make sure that the axle ends did not stop the vice jaws pushing the wheels to the correct B2B.

 

Or as I did on my next one make two more, and mount one in the headstock and one in the tail-stock of the lathe and use the tail-stock to push them onto the taper.

 

If you would like a sketch of them let me know.

 

OzzyO.

[Western Star]

Or as I did on my next one make two more, and mount one in the headstock and one in the tail-stock of the lathe and use the tail-stock to push them onto the taper.

 

If you would like a sketch of them let me know.

 

 

Yes please Paul, regards, Graham