For my next trick

How complicated could it be? It's just a large basic 0-6-0 loco design with a bogie added on at the front. The more experience one gains the easier kits are to build - except one starts to want all and any information available about the prototype and a photo of each side taken on the same day before starting assembly

Greg.P.

That depends on the designer :-) Bought a beautifully built but unpainted Patriot, could haul huge quantities of coaches, had to look closely to see any solder - so well made. However it didnt go round curves. Had axle washers to make sure it didnt go round curves - including on front bogie. Wheels are out, rods are off, most brake gear removed, b*gger will go round curves when I've finished with it.

Information on prototype, reach for book - 'Toms and Essery, Claughtons and Patriot 4-6-0s' - Drawings, photos and descriptions galore. Still got to look at it though.

Cheers, Simon

Cheers, Simon

Here in NZ we have kit makers and 4-8-4 locos. The locos are designed to go around infinite radius curves (on HO track) but can easily be loosened up to go around about 6' radius. Of course not everyone has 6' radius so I sometines get people asking how to get them around 2' radius. (Not easily)

You really want to get the side movement into the center driven axle, unless of course you've got worm drive there.I always minimise wheel side play within the bogies so that the bogie block has to move. That way it's easier to add side control. Became somewhat knowledgeable on the subject because I started scratch-building locos about 1970 and my HO minimum radius was and still is 360mm/15". It atakes a lot of though to get some locos around that radius!

Sure - my problem is I model locos from when cameras weren't so common and photographers generally photographed the latest, largest and fastest.

Greg.P.

SNIP....

interesting, instinct says should be side play on front and rear drive wheels, could do a scale drawing and confirm but worm already on rear axle. Might swap motor (X04) and gear anyway so could move it if wanted to. There was zero side play on any axles, even had rubber or fibre washers to ensure that. Removed from front bogie but was hitting cylinders so moved on to driving wheels. After bit of filing they have enough sideplay but problem with clearence for rods. Dont know who manufacturer was but width of coupling rods huge so not sure if was designed for curves. Filed those down at ends, filed crankpins to just enough and now putting rest of valve gear back in place. Should be ready for trial soon, if not right then maybe consigned to waiting list for a while ;-)

Takes me enough time to kit build so scratch building quite a way off (if ever) yet.

cheers, Simon

The ideal position(s) for fixed (no sideways movement) axles is around 70% of length from center point to end of the unit. Picture a bogie carriage - about where the bogie pivots fall. That puts the "offset" or overhang even at each end and center. Of course the "ideal" positions rarely work out on a steam loco. You probably want a bit less overhang to match the cab to the tender. (lose a bit there and it reappears at the other end or middle) the bogie has to swing on a 4-6-0 and generally that limit comes when the second axle/wheels) meets the valve gear. You can limit both the bogie movement and the leading driver side movement if wheel/valve gear contact becomes a problem.

My first action before building a loco (after scale drawing) is to lay a minimum radius curve line on paper (CAD these days and overlay a loco center-line with buffers and axle spacing on it. The driven axle has to be fixed on the curve, so the loco line is swung around that point until acceptable side movement compromise is found. For 0-4-4s and 4-4-0s there miight well not be an acceptable compromise.

0-4-4t I made the mechanisim as a bogie so it's like a coach. 4-4-0 I made the second bogie axle fixed in the frame, basically making it a 2-6-0 without drive on the second axle. 4-6-4 is my worst/unsolvable as it sits rigidly on the two outer driving axles and the ends wander all over the scenery.

Rod width is worst mechanically when outside cylinders are near to scale width. If your wheels are going to move sideways then you have to have clearance. With 3 axles coupled straight rods will force the axles to stay in line so you really need them in two parts. The easiest way to do that is to use two sets and cut them for two axles each. That might require you to file the overlaps down to

2/3 - 1/2 thickness. Easiest way to get two sets is to buy an extra set from the makers :-)

I learned scratch building from K's kits - by the time I finished my first one I'd scratch built everything other than the wheels. (bought those)

Greg.P.

SNIP>

Very useful - although certainly at the moment much is beyond my patience/capability, have to hope the designer has thought of these points :-) When it comes to rods in NS then theres some luck involved with the care to solder them in line and not to file too much off. However these were solid brass. This looks a very well made kit, but at least 30 years old so original manufacturer may not be around now. Replace bits of K's kit - but the 2 have done look fine to me. recently bought another - black 5 - valve gear looks a bit chunky but not sure can safely replace even if wanted to.

One question - is it possible to straighten a white metal piston rod ?

cheers, Simon

"simon" wrote

Bought a beautifully built but unpainted

I remember (some years ago) being offered a beautifully built O-gauge 9F

2-10-0 - it look absolutely stunning. However, the first thing I did was to turn it upside down to check the free side-movement on the driving wheels - there was none whatsoever!

I told the seller there was no way it would go round any model curves, but he claimed it would do 4'0" radius, so we set up a simple rig - one Peco point and two yard lengths of flexi-track. Guess what - it wouldn't negotiate the curved road of the turnout.

The lying scumbag of a seller was given short shrift and to go forth and multiply!

John.

On 08/06/2010 02:57, simon wrote: [...]

If it's a slight bend, I wouldn't risk it, esp on an old kit. The white metal may have begun to crystallise. Might be better to just enlarge the hole in the cylinder casting enough for smooth operation. You'll have to judge whether the resulting slop in the motion is acceptable. Don't do it if the resulting sideways motion of the crosshead is sideways, as it will likely interfere with the valve motion.

OTOH, if straightening the part works, OK. If it doesn't, look for a new part, or make one from NS. ;-) I've corrected _slight_ bends in white metal parts by gently tapping the part with a small hammer while the part rested on a piece of wood.

cheers, wolf k.

Thanks for that, afraid that was the case. Will try replace with brass rod, then try replacement part - bought a couple of comet xheads just in case.

cheers, Simon

Method 2. Presumably the piston rod is round :-) I would try rolling the rod between two pieces of flat metal. Waaaaay back I picked up a piece of 1/4" steel plate, about 2" x 5" with nice square edges. It's amazing the number of jobs it gets used for, anvil, square, surface plate, flattening xyzs, press ... I try not to hammer it and I know it's not a precision tool. (sorry, wandered a bit there) Old whitemetal may have deteriorated, particularly anything as small a cross-section as a piston rod. It's also soft, more suited to bearing surfaces than working parts.

Greg.P.

Thanks - now that one I do know about - regularly use to straighten wire, however it would require removing it - still before trying to replace .....

Cheers, Simon

Would annealing white metal reverse this process and make it less likely to break? I came across the following:

"White metal 92% Tin SN, 8% Antimony Sb no copper is annealed at

200'C-225'C or 392-427'F"

at

Alan

Well, they appear to know what they are talking about. ;-) Is it=20 relevant to this thread? I have my doubts.

Basically, we don't know what alloy was used to make the bent piston=20 rod. So there's a real risk attempting to anneal a casting. Most alloys=20 have a melting range, that is, they soften and turn into mush as they=20 approach the liquid temperature. But alloys suitable for casting are=20 selected to have a melting point, at which they liquefy almost=20 instantly. An attempt to anneal the piston rod may produce a nice little =

puddle of liquid metal.

Related problem: "white metal" is a vague term. From Wikipedia:

"The white metals are any of several light-colored alloys used as a base =

for plated silverware, ornaments or novelties, as well as any of several =

lead-base or tin-base alloys used for things like bearings, jewellery,=20 miniature figures, fusible plugs, some medals and metal type.

Some of the metals that make up a white metal alloy are antimony, tin,=20 lead, cadmium, bismuth, and zinc. Not all of these metals are found in=20 all white metal alloys but are mixed to achieve a desired goal or need.=20 As an example, a base metal for jewelry needs to be castable,=20 polishable, have good flow characteristics, have the ability to cast=20 fine detail without an excessive amount of porosity and cast at between=20

230 =B0C and 300 =B0C (450 =B0F and 575 =B0F)."

In addition, alloys made for pressure-casting may contain aluminum=20 and/or copper. Model railway parts are often made from these alloys. The =

zinc-bearing alloys are most prone to crystallising. AFAIK, once a=20 zinc-bearing alloy begins to crystallise, the process cannot be=20 reversed. It is caused by impurities in the alloy reacting with the zinc.=

"It's all rather confusing, really."

cheers, wolf k.

Any moment now you're going to find that scratch-building is quicker than kit assembly ;-)

Regards, Greg.P.

Well there are a couple of chassis that would like to make and have got the metal....;-)

DJH kit arrived - wow its got instuctions with excellent looking diagrams !

Cheers, Simon

I started making chassis on the kitchen table with a Black and Decker in one of their $5- drill press stands.(plus school ruler, engineers square and a school compass for a scriber. I soon added an old flat file and a nasty grind stone for the B&D. Main problem was finding times when my wife didn't want the table.

DJH kits are pretty good - needed to make a new chassis for the 2-12-0 but otherwise most of mine are as DJH intended.

Greg.P.

Using Opera's revolutionary e-mail client:

Thanks for the information. So it's not possible to reverse the crystallising and the annealing temperature is likely to be so close to the temperature when it starts to melt or go "pasty" that damage to the casting is likely to be the result. My interest in this is that I have an old unmade K's Duke kit which has a distorted boiler due to something heavy being stored on top of it and was hoping there was some way of making the quite thick white metal more easily worked to press out the dent without cracking it. I think it will go back into store to be discovered in hopefully many years time when my heirs dispose of my "estate".

Alan

Ever hopeful, i wopuld plan to find a piece of copper pipe of the approximate diameter. have read one or 2 articles where theyre scratchbuilding and done this - luck or what ? Of course if its taper boiler then not so easy, but with Swindon standardisation isnt there a similar size/shape old Hornby model that can donate one. Also if its that useless, would try straightening it (curving it) as its useless as it is but if you can get the general shape back cracks/breaks missing pieces can be filled/filed or soldered.

cheers, Simon

Will just nip back in time and answer part of this ;-)

Thanks for info, have assembled valve gear and chassis still runs ! Castings - white metal and lost wax - are bit rough in my opinion compared to K's or GEM ! Lots of big stuff needs filing and (ok limited knowledge bit) channels seem large and badly positioned - have to file out at corners some of which are on outside. Etch fine. Instructions - well main diags good but otherwise its mostly fit parts X and Y together, good luck. Trouble is having now assembled everything have found chassis dont fit body. Cylinders bit wide - ok theyre white metal so can file easily but hate filing when such delicate parts nearby. Motion bracket is fraction too wide. Now this I folded where marked (couple of dimples, not fine half etch fine line), need to fold bit more. What fun with assemb....oh said that before.

It could be said this is my own fault for tackling it as first valve gear (experience limited to fiddling with prev assembled stuff), but am not so sure. A warning in the instructions at the relevent place would be better. There is an extra section on valve gear which maybe has been inserted to make up for previously noted shortage. Dont think experience is supposed to be a panacea for lack of instructions or poor castings !

Would I recommend this kit to someone with my ability before started it - well yes with qualifier to warn about above. Whilst this may be a friday afternoon job in terms of castings, the instructions are sadly lacking.

Cheers, Simon