0-4-0STs

andrewnummelin
Posts: 374
Joined: Mon Jul 21, 2008 9:43 am

0-4-0STs

Postby andrewnummelin » Mon Mar 02, 2020 11:03 am

Having got into difficulties with a couple of projects I decided to try something simple and build a couple of kits of simple locos so I started in the autumn in Great Missenden and all went well to start with. I found some problems with the design of one kit and subsequently I realised that I'd also made a couple of serious mistakes which have resulted in me completely taking the chassis to pieces - I'm expecting to be able to re-use the side frames and motor and I'm keeping my fingers crossed about the wheels and gearbox. A second attempt at my first split-frame CSB chassis is next but one on the workbench.
So onto the second kit, a K's white metal one I've had in the cupboard for well over 30 years. To keep things simple I opted for a rigid driving axel and a compensated front one and to use an Ambis etched chassis in place of the K's OO one. Eventually the little thing is complete and just needs running in.
TVR267.jpg

One new thing I tried with success, thanks to help and encouragement from Ian MacCormac, was making ink-jet printed transfers for the numbers on the buffer beams. However things were not all plain sailing - the first serious problem was that the crank throw is so small that the wheels don't fit the GW wheel press, and with such small wheels and relatively deep frames sighting of the spokes to aid quartering was something I thought I would not be able to manage. So I made my own quartering jig.
jig.jpg

I used the largest piece of brass I had but ideally it should have been bigger so that it would have fitted outside the motor. Still, it did the job I needed.
The intention of Ambis was that the K's coupling and connecting rods and slide bars should be used and I went down this route, aiming to keep things simple rather than try to make new parts with a more prototype appearance. This was probably not a good idea as the resulting fiddling to get things to work may have taken more time than would have been spent on making things from scratch. The problems arose from the design of the original kit being for OO with the Ambis chassis appearing to have the cylinders at the prototypical distance apart - clearance behind crossheads are often a problem but having the connecting rod offset to the inside of the piston rods, thicker than scale wheels and, I think, a less than optimal crankpin bush resulted in "good fun"!
Then despite the chassis having run fine before fixing the gear wheel to the axel the final set up would hardly run at all. It appeared that the main problem was that the worm was too tight against the gear wheel: the bodge was to insert a shim between the motor and gearbox. There is still some problem in that the loco runs much better in one direction than the other - hopefully running in will improve this.
The final problem was with the pick-ups as there is almost no space for them and I fear any slight bump may cause problems with them touching either the frames or the brake rods. I had hoped to fit a stay-alive capacitor with a DCC chip but it proved impossible to squeeze one in. Wish me luck when I get back to working on the chassis for Trojan!
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Regards,

Andrew Nummelin

Enigma
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Joined: Tue Aug 13, 2013 2:49 pm

Re: 0-4-0STs

Postby Enigma » Mon Mar 02, 2020 2:11 pm

Interesting 'crankpin jig'. Could you provide some more details? I also found the same problem with small wheels' crank throw - but I can't remember how I got over it!

I've always fancied one of these K's kits but they go for silly money these days - and as you've noted, there's a lot of work to be done for a P4 version.

Stuart Firth
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Re: 0-4-0STs

Postby Stuart Firth » Tue Mar 03, 2020 1:26 pm

Very interesting and it looks great. I'm just building one of these myself, also with an Ambis chassis. At the Stevenage show I saw that Alan's latest version of that chassis kit is now in Nickel Silver and does include rods, so even more of a bargain!
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andrewnummelin
Posts: 374
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Re: 0-4-0STs

Postby andrewnummelin » Thu Mar 05, 2020 4:13 pm

Stuart Firth wrote:Very interesting and it looks great. I'm just building one of these myself, also with an Ambis chassis. At the Stevenage show I saw that Alan's latest version of that chassis kit is now in Nickel Silver and does include rods, so even more of a bargain!

Looking very nice Stuart. Are you finishing it in GW livery and with the cab side sheets? (I noticed the tool box rather than chain dogs.) Unless the back is not yet fixed I think you will have fun finishing the cab interior!

I don't know how you are going to arrange pick-ups, but here are a couple of shots of my effort. Each side is a single bit of phosphorbronze wire coiled round the screws and soldered to pcb. I added tiny bits of wire insulation to go between the brake pull rod and the chassis but on one I found this restricted the movement of the wire so I pulled it off - I hope it doesn't now occasionally make contact with the chassis. Rather fiddly - I'm sure there must be a better way!

DSC04818.JPG

DSC04817.JPG
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Regards,

Andrew Nummelin

andrewnummelin
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Re: 0-4-0STs

Postby andrewnummelin » Thu Mar 05, 2020 7:11 pm

Enigma wrote:Interesting 'crankpin jig'. Could you provide some more details? ...


The idea is a variation on the GW Models concept. I felt that I did not have the skills to modify the GW one for small crankpin throws.

I started with the largest diameter brass bar that I had and turned the two major components of the jig, drilling & reaming them 1/8" for an axle.
DSC04819.JPG


These were then clamped together with an axle in place and 4 holes drilled and reamed for alignment rods based on what I had in stock. The drilling was done on my mill.
DSC04820.JPG


The two parts were marked at as close as I could get to 90° to set the quartering. Each one was then had a slot cut with an end mill down till the axle hole. The cut (to the right) being long enough to take the crankpin: the limit on the left was set to leave around 1mm thickness in the end. This stage was included as I was not confident of being able to cut a 1mm slot deep enough for the crankpin through the full thickness of the part.
DSC04821.JPG


The parts were then remounted and a 1mm end mill used to cut the slots for the crankpin.
DSC04825.JPG


Lengths of axle were then cut to just under the lengths of the main bits and small stops turned to go in the ends to force the axle to just protrude from the jig.
DSC04822.JPG


To assemble the wheels and axle, everything was mounted and the lot clamped in a vice so forcing the main axle to just enter the wheels. The set up was removed from the vice, the stops removed and in the vice the wheels were pushed home against a back-to-back gauge.
DSC04823.JPG


The only critical dimensions were the holes for the axle and alignment rods and the width of the slot for the crankpin.

What would I suggest doing differently?
1. Use a much thicker bar to start with so that the jig would extend well beyond the model.
2. Use thicker alignment rods that the above would allow. This would increase accuracy.
3. Think about matching the face of the jig to the profile of the wheel face. I included a small ridge to ensure the wheels were pressed on by the centre boss rather than the rim to avoid any risk of pushing the tyre off the centre. Ideally one would push at the centre while supporting the tyre. Perhaps a recess in the jig with a variety of inserts for different types/sizes of wheel.
4. Think about making the bits of axle and stops accurately enough to ensure that wheel pair would centre on their axle even if the axle was not exactly the right length.
5. Use separate bearings and hornblocks rather than try to assemble things round the chassis with bearings fixed in the frames. Trying to get motor, gearbox, frames, wheels, axels, quartering jig and back-to-back gauge all together was not fun! Perhaps CSBs would be easier with this type of loco.
6. Pick a different prototype!
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Andrew Nummelin

Stuart Firth
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Re: 0-4-0STs

Postby Stuart Firth » Fri Mar 06, 2020 8:31 am

That's a serious piece of kit - you are obviously a very capable engineer. I'm not..... which is perhaps why I've always taken a rather 'slapdash' approach to quartering. I just set a datum axle then grip the wheels on the other with thumb and forefinger of each hand and twist. Check both crankpins on one side are facing directly downwards, then check to see if the pins on the other side are at 90 degrees and facing exactly the same way. If not, twist a bit more. It does work, the eye is surprisingly good at spotting tiny errors, at least if I'm wearing my reading glasses, and if they are less than tiny they don't matter. I did actually buy a secondhand quartering jig at Scaleforum but I've managed for 35 years without one until now.

Will post pick up pics. at the weekend. Nothing very high tech there either !

I love the character you have put into that loco - the paintwork, the pipework, it just looks the part. I'm an industrial modeller so mine will be a generic Hudswell Clarke and Rodgers from the late 1870's, in my fictional company's livery, which is actually GW green..

Enigma
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Joined: Tue Aug 13, 2013 2:49 pm

Re: 0-4-0STs

Postby Enigma » Fri Mar 06, 2020 12:08 pm

Many thanks Andrew, a very interesting idea. I've always thought that milling with a 1mm cutter could be a bit fraught! Plenty of light cuts I suppose.

Stuart Firth
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Re: 0-4-0STs

Postby Stuart Firth » Sat Mar 07, 2020 9:23 am

No pick ups yet but I think they will look very like the similar Manning wardle 'F' - backscratchers of brass wire soldered to PCB araldited inside the frames:
WP_20200307_08_47_38_Pro.jpg

WP_20200307_08_50_40_Pro.jpg
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Clive Impey
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Re: 0-4-0STs

Postby Clive Impey » Sun Mar 08, 2020 6:10 pm

I set up the fixed axles on my compensated locos so that they can be removed if required. I use High Level axlebox and hornguide units installed as per instructions. The axle box has a block of brasss soldered to the top which is filed down so that when the box is in the hornguide the hole in the box is in line with the axle datum line. Another piece of brass is soldered to the bottom of the box and is filed untill the retaining wire in the base of the hornguide holds the box firmly in place. Removal of the wires allows the wheelset to be dropped out of the chassis. Doing this really does make tuning the chassis so much easier.

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Andy W
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Re: 0-4-0STs

Postby Andy W » Sat Mar 14, 2020 8:19 am

I’ve made “rigid” axles with HL hornblocks removable by simply using wire that’s too thick to allow any springing and just serves to hold the block in place. The wheels can then be dropped out when needed.
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Enigma
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Re: 0-4-0STs

Postby Enigma » Sun Mar 15, 2020 1:21 pm

My take on simple compensation 0-4-0 chassis (or even 0-6-0) with a 'fixed' but removable axle. The axle hole is reamed to a good fit for a top-hat bush. The hole is extended downwards to become a slot taking care to make it just wide enough to slide in the bush. A length of small bore brass tube is soldered across the bottom of the bush (which is pushed up to the top of the slot) and the sides of the slot. the tube is cut with a razor/piercing saw either side of the bush. An 'L' shape piece of good fitting brass wire is slid into the now 3 sections of tube so retaining the bush - and therefore the axle - in the slot in it's 'fixed' position.

IMG_9743.JPG


Here a longer piece of wire is used to retain both axles, omitting the centre section on the pivoted axle for rocking clearance. Other locos have a short piece just for the 'fixed' axle with some other method (eg keeper-plate style copperclad for mounting pickup wires) for the rocking one/s.
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