Lisa
Statesman
Posts: 806
|
Post by Lisa on Oct 31, 2015 5:04:38 GMT
Go metric, I swapped all the BSF threads for metric and will stick with metric except for boiler fittings which are BSP or ME. This is what I'm leaning towards, metric for everything except boiler fittings, simply because I don't think it's worth losing the interchangeability with commercial fittings. Roger, that is an extraordinarily useful chart, and Knupfer seem to have a good range, so thanks. Not quite as easy as the overnight delivery I can get with BA fasteners locally; but I'd imagine that the more of us that use metric, the easier it will be to get a hold of.
|
|
Lisa
Statesman
Posts: 806
|
Post by Lisa on Oct 30, 2015 15:30:28 GMT
So I'm having to restock/refit parts of my workshop as I get back into model engineering, and in the process I've left myself wondering about BA threads. Back before my dad sold off a large chunk of the tools, we had been in the process of switching to an entirely (or mostly) metric workshop; metal stocks, drills, taps, dies, etc. Of course it never would have been entirely metric, as most (older at least) designs are drawn in imperial, and most fittings are ME threads; but new machine tools are metric, as are most metal sizes. Thus things like axles are 20mm instead of 3/4", use a M5 tap instead of 3/16" and so on, with imperial dimensions used only where necessary.
This brings me to where I am now, and particularly in replacing smaller taps and dies.
The smallest tap/die I currently have is 3mm, below that I need to buy new as the old sets got sold off (or were claimed by my brother, and thus either lost or broken by now). So I'm wondering if I should get new BA taps/dies, or switch to the metric equivalents.
Going all metric would simplify some things such as identifying a thread, and the idea of a "standard" thread type feels somewhat more organised to me. Anytime a BA (or other) thread is specified on a drawing, I'd just use the nearest metric equivalent, as there's metric thread at 0.2mm (or less) intervals in the smallest sizes, down to 1mm; equivalents to 0-14BA, plus some in between. But, smaller metric fasteners are not necessarily easy to get hold of, so I'd likely end up having to make a lot of nuts and bolts myself.
On the other hand if I stick with BA for small threads then fasteners are easier to get hold of, compared to the smaller metric sizes. Plus there's no need to deviate from the design. But there'd also likely be a crossover point, either in the case of a project having larger threads in metric, and smaller in BA; or in having both metric and BA tools and fasteners on hand, and choosing one or the other depending on the project.
I've been dithering on what to do for a while, but I'm going to need to buy one or the other (or both) soon, so I thought I'd share my indecision with you all.
Basically this is my chance to go all metric, if I want to, which I'm not sure if I do.
Any thoughts?
|
|
Lisa
Statesman
Posts: 806
|
Post by Lisa on Oct 30, 2015 5:14:04 GMT
That's quite brilliant Roger, I probably would've just use round wire, so nicely done.
|
|
Lisa
Statesman
Posts: 806
|
Post by Lisa on Oct 29, 2015 9:51:14 GMT
Biggest possible lathe I could manage on the budget, bought the table for a milling machine (a big one) and some how attached it. That way it would have XYZ movement, tons of head room, it would just be.... totally sideways. It could do the precision work like that a normal mill could- right? As I said back at the beginning of the thread: You might be able to get by without a mill if you have a vertical slide for the lathe; this will allow you to do milling in the lathe. This would give less for you to move, so you could probably offset it by having a slightly larger lathe. I generally consider a mill to be somewhat of a luxury item; it's nice to have, it makes some jobs easier and quicker, but it's not essential. You can do most - if not all - milling operations in the lathe, either with a vertical slide, or by clamping the job to the cross slide. In the unlikely event that you manage to find something that can't (with a little planning) be done in the lathe, then as you have access to a mill at your club it's not an issue anyway. If you can afford - and are able to move - a mill along with a lathe then by all means get both. But a decent lathe and a bit of ingenuity will be enough to build your loco otherwise.
|
|
Lisa
Statesman
Posts: 806
|
Post by Lisa on Oct 25, 2015 8:30:40 GMT
You might be able to get by without a mill if you have a vertical slide for the lathe; this will allow you to do milling in the lathe. This would give less for you to move, so you could probably offset it by having a slightly larger lathe.
For loco's, the simplest conversion for 7¼" -> 7½" gauge would likely be something with inside cylinders and valve gear; you could then simply build to plan but with longer axles and a spacer bush between the back of the wheels and the axle boxes.
|
|
Lisa
Statesman
Posts: 806
|
Post by Lisa on Oct 23, 2015 17:23:41 GMT
We used to follow a simple rule of thumb: fixed wheelbase in inches = minimum radius in feet. Add an extra 50% to that for curves you don't have to take overly slowly.
|
|
Lisa
Statesman
Posts: 806
|
Post by Lisa on Oct 22, 2015 5:03:31 GMT
Julian, I suspect that's why it was suggested as a first injector.
|
|
Lisa
Statesman
Posts: 806
|
Post by Lisa on Oct 21, 2015 16:21:38 GMT
|
|
Lisa
Statesman
Posts: 806
|
Post by Lisa on Oct 21, 2015 12:06:12 GMT
I was just flicking through some old issues of Australian Model Engineering, and came across an article by Ted Crawford on Making Injectors which was serialised in the May-June, July-August, and September-October 2002 editions. Of note is a design for a solid mixing cone, which apparently is a drop-in replacement for the split cone used in the example 60oz design mentioned throughout the series. Thought some here may be interested.
|
|
Lisa
Statesman
Posts: 806
|
Post by Lisa on Oct 20, 2015 14:56:12 GMT
Have just bored out the crankpin hole on one of the front coupling rod bosses. This took a couple of hours as the little Taig II lathe can't drill bigger than 10mm, so a great many 5 thou cuts followed to bring it out to 16mm for the bush, then a 2mm deep 20mm counterbore for the retaining collar to fit in.
|
|
Lisa
Statesman
Posts: 806
|
Post by Lisa on Oct 20, 2015 6:27:51 GMT
Hi, for our 5" gauge portable ground-level line we used to use 1"x3/8" rail, welded to 3/4"x3/16" ties at 12" spacing, with 12" long 2"x1" wooden sleepers screwed to those. You'd probably want to opt for something like 2"x3/8" rail with supports at 36"-48" or so for an elevated track.
This is based off experience of commercially operated lines, you may be able to get away with less for a home track. Just remember that the heaviest thing on the track is likely to be the driver/passengers, so build according to what you think would safely hold several people standing on it. Also, adding a 3rd rail to give 5" (or 4.75") gauge for the riding car(s) isn't unusual for an elevated line.
|
|
Lisa
Statesman
Posts: 806
|
Post by Lisa on Oct 19, 2015 8:02:52 GMT
Michael, "The 4mm Coach" by Stephen Williams, and published by Wild Swan has a chapter dedicated to the Ratio kits for these, with some prototype photo's, and a few drawings. "Historic Carriage Drawings" by David Jenkinson and Nicholas Campling, and published by Ian Allan apparently has full drawings for them.
Also, if you use Firefox as your browser, it has a built-in PDF reader with search function.
|
|
Lisa
Statesman
Posts: 806
|
Post by Lisa on Oct 17, 2015 10:21:43 GMT
I was just doing one of my occasional-semi-regular check ups on some of the preserved lines around here, and found some photo's I thought some here might be interested in. The Australian Narrow Gauge Railway Museum Society had a loco donated to them last year by the Dreamworld theme park, who now diesel haul their train(s). The loco, a Perry 2' gauge 0-6-2T was/is in need of quite a bit of work after being run into the ground by the theme park, and ANGRMS' July/August Bulletin has an update of the progress, along with some pictures such as reprofiling the pony truck wheels, and some shots of inside the steam chest of one cylinder, both with and without the slide valve. It's toward the end of this: www.angrms.org.au/drb/drb_334.pdf
|
|
Lisa
Statesman
Posts: 806
|
Post by Lisa on Oct 16, 2015 7:02:06 GMT
Joan, Not sure if these will be of use to you or not, but I thought I'd put the links up in case you're interested. The Australian boiler codes include a section for stainless steel boilers, and a code of practice for gas firing. The duplex stainless boiler code is just the index, you need to buy the actual code if you're interested. www.aals.asn.au/AMBSC/AMBSC_Code4.htmThis is the full code of practice document for gas firing. www.aals.asn.au/Resources/CoP%20Gas.pdfHope there's something in there of use to you.
|
|
Lisa
Statesman
Posts: 806
|
Post by Lisa on Oct 15, 2015 15:26:17 GMT
what you are proposing is similar to the conn rod and coupling rods on the Ffestiniog Railway George England 0-4-0 locos. cheers, julian The QR A10 (which I have 5" gauge drawings for) was where I got the main inspiration from, but yes looking at the few semi-decent rod close ups I could find of the George England loco's they're about the same; though I'm just going for a round bush in a hole rather than what looks to be split bushes in a slot on those?
|
|
Lisa
Statesman
Posts: 806
|
Post by Lisa on Oct 15, 2015 15:15:56 GMT
Just to show I am actually doing stuff, here's the coupling/connecting rod bosses (as per earlier drawing) getting machined to size in the lathe. The close up makes the bench look messier than I thought it was. The lathe is a Taig II (Peatol), which is the only lathe I have at present, while small, it's had quite a bit of use, and will do just about everything except the cylinders; to give some idea of size, that chuck is 4" diameter. The other 5 bosses are sitting on the cross slide for the photo. All have been machined to length, currently machining to height, next machine to width. Then I'll bore the holes for the crankpins and bushes (on one 'end' anyway, will drill the other crankpin hole once the rod is assembled so I don't end up with the wrong dimensions), and then drill the holes for connecting them together into a finished rod.
|
|
Lisa
Statesman
Posts: 806
|
Post by Lisa on Oct 6, 2015 8:26:51 GMT
Ian, Sweet Pea is pretty much where I got the idea from. I've got a GA from the original EiM(?) series that we had photocopied and enlarged to actual size. Pretty sure the magazines were sold with the loco though (my dad's last loco was a heavily modified Sweet Pea - 0-4-2+T, briggs steel boiler, walschaerts valve gear). However as I recall Sweet Pea's coupling rods are marine style, with 8mm steel rod threaded and silver soldered to a small plate, with the bronze crankpin brasses bolted to that. Which is similar to what I'm proposing here, but with flat instead of rod between the bosses, and with bushed steel bosses instead of bolted on brasses.
|
|
Lisa
Statesman
Posts: 806
|
Post by Lisa on Oct 6, 2015 4:47:01 GMT
The last tender I built was a fairly large 7¼" gauge tender (sit in style), it was all steel construction and sealed with bituminous paint as sold for sealing old water tanks. That worked quite well. Not sure yet how it'll be on a smaller loco/tank, but I intend to use it for my Blowfly's side tanks.
|
|
Lisa
Statesman
Posts: 806
|
Post by Lisa on Oct 5, 2015 17:13:53 GMT
Up late (not unusual for me, especially in the warmer months) and doing some scribbling. Putting some thought into the coupling rods, and considering a bit of deviation from the original design for various reasons. The standard Blowfly design calls for 25x7mm steel, shaped into a dogbone (rounded ends, thin centre), the bushes are then wider than the rods/bosses, but not centred in them. I'm thinking of using 2 pieces of 25x10mm for the bosses/rod ends, joined by a length of 12x6mm which would be threaded and silver soldered into the bosses. The benefits would be: Less work with the hacksaw, and thus not wearing my arm out. What to me is a more pleasing shape. Centring the bushes on the rods would also centre the forces applied to the rods on the bearing surfaces, which could (maybe?) reduce wear; and would also centre the oil hole in the bush, thus better lubrication. Here's a quick workshop drawing I made of what I'm thinking:
|
|
Lisa
Statesman
Posts: 806
|
Post by Lisa on Sept 29, 2015 6:22:15 GMT
I know in these parts there's very few 3½" (or 2½") gauge tracks around; within a 3 hour drive of home there's one at QSMEE and that's it. On the other hand there's a dozen or more 5" and 7¼" gauge tracks.
Of course whether there's less loco's because there's less tracks, or less tracks because there's less loco's is unknown (and arguable).
I'm currently building in 5" gauge as when I started this loco my dad also had a (or several) 5" loco(s), and we had a track around the house. Plus I grew up with 5" gauge. On the other hand I'd quite like to build a LBSC Molly (3½" gauge LMS Jinty) at some point - and the first loco I ever drove, at 5 years old, was 3½" gauge - so make of that what you will.
I think 5" gauge is about as big as you can get while still being able to lift (at least to some extent) a loco on your own, which is probably part of it's appeal.
|
|