Gary L
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Post by Gary L on Dec 14, 2021 17:32:43 GMT
I've also made a small modification to the wheels and axles. Quite a few times I've read of others having the occasional wheel come loose and have decided to use locking screws to keep mine in place. In the back of the wheels, I have drilled a twenty degree hole using the tilting vice. These have been tapped M4 and cup-point stainless steel grub screws will be used. [Snip] Wheels can come loose obviously, but this is where coning is important. It allows the wheelset to compensate for the extra distance run by the outer wheel on a curve. This should eliminate any wringing strains on the axle joint. By contrast, parallel treads have no such relief mechanism, so when heavily loaded they are very prone to coming loose. Your wheels look to be correctly coned, so with your precautionary grub screw as well you shouldn’t have any problems! Gary
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Post by Jock McFarlane on Dec 14, 2021 19:54:56 GMT
I've also made a small modification to the wheels and axles. Quite a few times I've read of others having the occasional wheel come loose and have decided to use locking screws to keep mine in place. In the back of the wheels, I have drilled a twenty degree hole using the tilting vice. These have been tapped M4 and cup-point stainless steel grub screws will be used. [Snip] Wheels can come loose obviously, but this is where coning is important. It allows the wheelset to compensate for the extra distance run by the outer wheel on a curve. This should eliminate any wringing strains on the axle joint. By contrast, parallel treads have no such relief mechanism, so when heavily loaded they are very prone to coming loose. Your wheels look to be correctly coned, so with your precautionary grub screw as well you shouldn’t have any problems! Gary I had always understood that coning helped keep the wheels centred on the track so that flange contact with the rail was minimised and that coning has little to with the rail length differential . Coning at 3% has virtually no effect on the compensation of the outer rail to inner rail differential on curves. Assume a 50 foot radius curve in 7 & 1/4" and a 90 degree turn. The outer rail is 942.60 inches and the inner rail is 931.21 inches - a difference of 11.39 inches. This means that on a 6 coupled loco only 3 wheels are gripping and the other 3 wheels are sliding or slipping. Assume a 3% cone on a 10" wheel and that the wheels can move over by 1/4" due to track widening. This compensates only 0.45 inches out of the 11.39 inches of track length differential. Coning certainly looks better and is more authentic but I cannot imagine it helps stops the wheels from coming loose. Regards JM
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Gary L
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Post by Gary L on Dec 16, 2021 1:17:37 GMT
[Snip] Wheels can come loose obviously, but this is where coning is important. It allows the wheelset to compensate for the extra distance run by the outer wheel on a curve. This should eliminate any wringing strains on the axle joint. By contrast, parallel treads have no such relief mechanism, so when heavily loaded they are very prone to coming loose. Your wheels look to be correctly coned, so with your precautionary grub screw as well you shouldn’t have any problems! Gary I had always understood that coning helped keep the wheels centred on the track so that flange contact with the rail was minimised and that coning has little to with the rail length differential . Coning at 3% has virtually no effect on the compensation of the outer rail to inner rail differential on curves. Assume a 50 foot radius curve in 7 & 1/4" and a 90 degree turn. The outer rail is 942.60 inches and the inner rail is 931.21 inches - a difference of 11.39 inches. This means that on a 6 coupled loco only 3 wheels are gripping and the other 3 wheels are sliding or slipping. Assume a 3% cone on a 10" wheel and that the wheels can move over by 1/4" due to track widening. This compensates only 0.45 inches out of the 11.39 inches of track length differential. Coning certainly looks better and is more authentic but I cannot imagine it helps stops the wheels from coming loose. Regards JM Hi JM I'm the last person to take issue with someone else's maths, but I make the difference in circumference from 3 degree coning over .25" of tread to be 0.16465". Double it, because as one wheel moves out the other moves in, = 0.3293" difference over just one revolution of a 10" wheel. It takes approx 30 revolutions to cover the mean distance you quote. 30 x .16465" = 4.9 inches, before you come up against the all-important flange root radius which exponentially increases the difference. In practice, your assumption of only ¼" lateral movement might be questionable too. I wouldn't go to the stake over these figures, but I think there is enough to indicate that something might be adrift in your calculation. But computing to several places of decimals might obscure the empirical fact that coned wheels don't slip on normal curves. If they did, on grown-up railways, the wheel wear and strain on the axle joints and/or tyres would be unsustainable. On very tight curves, where normal coning is insufficient, there is "slipping and sliding" to be sure, and the squealing it generates can be heard for miles- thus the exception proves the rule. As an aside, I would add that the centralising effect of coning is not exactly as it seems either. There are plenty of demonstrations available on the net to prove it happens, but the truth is more complex. The demos rely on a single unconstrained axle which is free to find its own alignment radial to the curve. The reality is that in conventional (i.e. not self-steering) railway chassis, the axles are constrained, and can never adopt this radial posture,* which complicates the theory considerably. But the essential truth remains. Best wishes Gary * discounting the central axles of a fixed wheelbase of more than 2 axles, but these have no influence on curving.
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Post by springcrocus on Dec 18, 2021 8:50:12 GMT
Slide valvesI have made the valves and valve buckles from Pumphouse bronze and the valve spindles from stainless steel. After cleaning up all round, I formed the pocket on the underside of the valves with a small end mill. Once most of the material was cleared away, I crept up carefully to finished width, just a couple of thou per pass, because I wanted the size as accurate as possible. The length of the port is not important but the width is accurate to within a thou. The buckle was made next and this needed a little planning because the spindle is not central to the workpiece, being offset by 1/16". The blank was machined to 1/4" thick and a centre drill used to mark the spindle position. The work was then loaded to the independent 4-jaw on the lathe, trued up and the valve spindle boss machined to 1/4" diameter by 3/16" long. I then drilled and tapped it M4. Back on the mill, the material was cleared away from the middle using a 1/8" diameter end mill to get reasonably sharp corners before filing square. Then the thickness of the buckle was reduced to 3/16", all the material coming off one side. The parts were paired up and numbered so that I could get a good fit between the buckle and the valve. The outside of the valves were roughed out all round, then the longest dimension finished with about five thou clearance. Floating up and down doesn't matter and it will help to keep the valve free in the buckle. Next, the longer sides were milled to be a very precise but not sticky fit to the buckle. Having no play in this direction should help to keep the timing accurate. One of the club loco's had a problem with the valves. Both John the Pump and Wilf told me it appeared that the valve wasn't seating properly because there wasn't enough clearance behind it for steam pressure to push it down and effect a seal. With this in mind, I decided to mill some channels on the backs of the valves to try and overcome any Casimir-effect that might happen between the two valves. Angled at thirty degrees, they are 2mm wide and 2mm apart. I made a crosshatch on one of them but decided not to do that on the second, settling for a single direction only. Putting the valves back-to-back, they slide over each other without snagging so that appears to have worked. That's as far as I can go with these for now and they can go in the storage box until assembly time. The bench is getting a little cluttered at present so I'm going to put Calbourne aside for a while and concentrate on completing the Allchin. Regards, Steve
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jma1009
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Post by jma1009 on Dec 19, 2021 22:39:02 GMT
"One of the club loco's had a problem with the valves. Both John the Pump and Wilf told me it appeared that the valve wasn't seating properly because there wasn't enough clearance behind it for steam pressure to push it down and effect a seal."
Hi Steve,
I am not aware of any IWMES club loco with inside cylinders. 'Fishbourne' does not have the backs of slide valves sliding against each other. I would suggest there is some faulty logic at play here!
Cheers,
Julian
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Post by craigr on Jan 8, 2022 22:02:09 GMT
Hi Steve and fellow model engineers
I’ve been following along with your posts from your build of the Don Young designed Adams 02 and have found it fascinating. So much so that I have just bought a set of the plans for myself from reeves. I am 33 year old, and an aircraft engineer by trade but I have no machining training so will basically be buying a lathe and a mill and learning as I go so your photos and posts will be invaluable, and thank you for taking all the time to document what you are doing to help all the people our there like myself.
I have been studying the drawings for the 02 and it’s quite possible that I have missed it some where but I can’t seem to find the drawing of the regulator mechanism. I have found the handle and attachments to the rear firebox plate but the parts that are internal to the boiler and steam dome seem to be missing. Could you or anyone else that may know the answers please point me in the right direction.
Again I might be showing my inexperience but I can also not find anything on the drawings for a mechanical lubricator or axle driven water pump so wondered if you have any knowledge that you could share regarding these items on this type of loco. I have found some notes regarding all parts but on my copies most of the note is not readable other than hinting that the drawing for these parts can be found in a book or other documentation but I’m at a loss as to how to locate them
Kind regards
Craig
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Post by springcrocus on Jan 8, 2022 22:29:55 GMT
Hello Craig and welcome to the forum, I'm afraid I can't help you with your queries at present as I haven't got that far in my build. Unlike many others, I don't look too far ahead in the build process so haven't yet looked at the regulator or water feeding mechanisms. My pleasure is in making the parts. If they're wrong I just remake them. For me, it's all about the journey, not the destination. Normally, I would wander off to the workshop and get the drawings out, have a look and share what I've found but, as some on the forum will tell you, I usually lock up the workshop after Christmas and come indoors to enjoy my other hobby ("OO" gauge loft layout) until around Easter. Now that the weather has turned colder, that is what I've done and won't be going back to the workshop until it warms up a little. Hopefully, one of our others colleagues will reply, maybe Julian or Nigel Bennett. Nigel has nearly finished his one and has kindly sent me much valuable information, especially regarding the springing of the loco. Julian abandoned his model after finding discrepancies in the scale but is extremely knowledgeable regarding Don Young designs in particular, and miniature locos in general.
Kind regards, Steve
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Post by springcrocus on Jan 24, 2022 17:37:43 GMT
Another wondeful example of "draughtsmanship". Does anyone know whether the left-hand or right-hand view of the steam chest is correct, please? (hint - steam port placement) Regards, Steve
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Post by fubar123 on Jan 24, 2022 18:52:35 GMT
Marvellous
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samc88
Active Member
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Post by samc88 on Jan 24, 2022 18:59:10 GMT
I cant make out the dimensions on my phone but are they handed so the drawing shows both left and right? Although Im not sure why that would happen
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Post by Nigel Bennett on Jan 25, 2022 14:47:32 GMT
Hi Steve and fellow model engineers I have been studying the drawings for the 02 and it’s quite possible that I have missed it some where but I can’t seem to find the drawing of the regulator mechanism. I have found the handle and attachments to the rear firebox plate but the parts that are internal to the boiler and steam dome seem to be missing. Could you or anyone else that may know the answers please point me in the right direction. Again I might be showing my inexperience but I can also not find anything on the drawings for a mechanical lubricator or axle driven water pump so wondered if you have any knowledge that you could share regarding these items on this type of loco. I have found some notes regarding all parts but on my copies most of the note is not readable other than hinting that the drawing for these parts can be found in a book or other documentation but I’m at a loss as to how to locate them Kind regards Craig You won't find regulator detail drawings, Craig, because there aren't any! There's a note on one of the drawing sheets saying "Use standard LBSC type" or some such wording. There are quite a few drawings of regulators around in other designs, so you can possibly blag those. Mine's a three-start screw thread of my own design; I can never get disc-in-the-tube or Stroudley ones to seal properly. Similarly the lubricator internals. Axle pump - there's not a lot of room to fit one; the full-sized ones didn't have them! The crank axle is full of valve gear eccentrics, and there's very little room on the front one either, but you might just squeeze one in if you mount it on the front of the motion cross-stay. You'll have to rely on two injectors and the hand pump. I have also re-purposed the Westinghouse pump on mine as a steam water pump. It works on air but no idea if it does the doings on steam yet. Good luck with it!
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uuu
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Post by uuu on Jan 25, 2022 16:25:36 GMT
.. Does anyone know whether the left-hand or right-hand view of the steam chest is correct, please? (hint - steam port placement) ... Regards, Steve I'm guessing here - with no knowledge of the loco at all. If the valves are driven from the back, and the exhausts (presumably from the cylinders) are in the middle, then having the steam inlet at the front might make plumbing up the smokebox easier. Wilf
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Post by Nigel Bennett on Jan 25, 2022 17:03:45 GMT
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Post by springcrocus on Jan 25, 2022 19:08:01 GMT
Cracking job, Nigel, many thanks. I will print that off for constant reference.
Regards, Steve
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jma1009
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Post by jma1009 on Jan 25, 2022 23:41:59 GMT
I didn't understand Steve's post on the steam port presumably the entry of steam into the steam chest which is in the way of the cylinder to steam chest studs? Am I correct in this assumption?
There is a hollowed block on top of the steam chest. You will have to go to the ME articles for this.
I don't recall the regulator being omitted, but I haven't gone back through the sheets of drawings or the construction series in ME, so my memory might be faulty.
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Post by coniston on Jan 26, 2022 23:02:46 GMT
I didn't understand Steve's post on the steam port presumably the entry of steam into the steam chest which is in the way of the cylinder to steam chest studs? Am I correct in this assumption? There is a hollowed block on top of the steam chest. You will have to go to the ME articles for this. I don't recall the regulator being omitted, but I haven't gone back through the sheets of drawings or the construction series in ME, so my memory might be faulty. I assumed Steve was referring to the position of the steam inlet fitting. The left view shows it a the same end as the valve spindle glands but the section view on the right shows it at the opposite end to the glands. Or maybe I'm wrong? Chris
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Post by ettingtonliam on Jan 27, 2022 9:03:39 GMT
Thats how I read it too. Nigel's drawing suggests that the correct answer is to have the inlet at the gland end. Without seeing the whole drawing, I can't give a reason why the original drawing is as it is.
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Post by springcrocus on Jan 27, 2022 9:12:02 GMT
I didn't understand Steve's post on the steam port presumably the entry of steam into the steam chest which is in the way of the cylinder to steam chest studs? Am I correct in this assumption? There is a hollowed block on top of the steam chest. You will have to go to the ME articles for this. I don't recall the regulator being omitted, but I haven't gone back through the sheets of drawings or the construction series in ME, so my memory might be faulty. I assumed Steve was referring to the position of the steam inlet fitting. The left view shows it a the same end as the valve spindle glands but the section view on the right shows it at the opposite end to the glands. Or maybe I'm wrong? Chris Bang on, Chris! Wilf and (the other) Chris also spotted it straight away. Thankfully, Nigel's excellent GA drawing shows it to be positioned at the valve spindle end. It annoys me that the copyright holders of these drawings still peddle them whilst steadfastly refusing to update any errors noted to them. Basically, we model engineers are paying good money for s**t. Anyway, rant over.
The wife wanted me out from underfoot for a few days and shooed me out of the house so the heat was turned on in the workshop and I've used the time to complete the steam chest. Update tonight. Regards, Steve
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Post by springcrocus on Jan 27, 2022 19:09:43 GMT
Steam chestThe draughtsman suggests making the steam chest from a 3/4" thick block of gunmetal and brazing the upper steam chamber and it's connection point on the top. I've chosen to make it differently, using a couple of pieces of the 1/2" thick Pumphouse bronze plate. Starting point, as always, was to square up the two billets to the maximum dimensions, then remove the waste from the centre of each. Once again, I've used a 4mm carbide slot drill to track round in a rectangle using plus and minus co-ordinates on the DRO. I also pre-drill four corner holes 4mm diameter so that the slot drill doesn't need to plunge-cut unneccessarily. I prefer this method to stitch-drilling because the resulting billets are perfectly square and ready to be used on another job. This was followed by facing both sides was my large flycutter. With the billets cleaned up all round, the upper steam chamber was milled out next to a depth of 3/16". The fixing holes were drilled next so that I could position the steam slots, then realised that I didn't need to make them as per drawing and just milled them 5/16" wide by 3/16" deep. To assist with location, I also drilled a pair of 3/32" dia dowel holes at two corners. I painted the insides of the fixing holes with correction fluid to stop the solder running away and then the two billets were given a light rub over some fine emery cloth. The faces were fluxed, a ring of 1mm dia silver solder shaped to fit all round and rest in between, the upper one placed on top and a weight above that to help gravity do it's thing. Unfortunately, I forgot to take a picture at this point. It took a few minutes to get up to temperature because of the mass but, eventually, the top section settled down on the lower part and heat was removed. The photo taken afterwards shows the two corner dowels in position. I've definitely had a good melt because solder has wicked up the dowels even though they weren't fluxed because they will be milled away. The next couple of ops were about getting the outside shape. First was to mill all round the upper steam chamber... ... followed by facing the inboard end to length and forming the valve spindle ports. I'm using 4mm dia stainless for the spindles and have also changed the gland-fixing screws to 8BA rather than 7BA. 5/32" x 5/16" "O" rings will be used as packing. The surplus material was then cleared away from the face, ready for shaping the dual spindle boss. Following some sound advice from Nigel, I also drilled and tapped a couple of 4BA holes at top of the front face to assist with valve-setting. A couple of cap screws will seal them on completion. Final job was to create the steam inlet port and I'm making a change here. The drawing shows a threaded tube soldered to the top of the steam chamber but I don't want to do any further soldering to this and am making a screwed flange fitting instead. A 5/16" dia was drilled through which was spot-faced with a 7/16" dia slot drill to take another "O" ring. Four 10BA holes were drilled and tapped, taking care not to break into the steam chamber. The fitting for the top was turned from 3/4" dia Colphos and threaded 1/2" x 40 because I have a matching tap and die but not a 1/2" x 32 as drawn. I've also formed a small undercut at the root because, otherwise, it will be a bit tight to get a spanner on. After parting off with a 1/8" thick flange, it was screwed into a mandrel (actually, my thread gauge) and loaded into a chuck on the mill. After seeing Nigel's drawing, it seemed sensible to have the steam pipe vertical but the cylinders are inclined by about six degrees so I set the tilting table to compensate. The flange was milled to leave 1/16" on the thinnest section, then the centre of the hole found and four 1.9mm holes drilled at +/- 0.218" for 10BA mounting screws. The fitting was then screwed to the top with the "O" ring in place. This shot shows the fitting inclined towards the front of the steam chest which will be vertical when all is mounted in place. And to finish off, here is a picture of the steam chest mounted between the cylinders with a couple of temporary studs and nuts. And this one shows the slide bars fitted to the top of the cylinder covers, making quite a nice, rigid assembly. That's it for now, back in the loft tomorrow. Regards, Steve
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uuu
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Post by uuu on Jan 27, 2022 19:32:36 GMT
I had wondered why you'd written on the drawing that you were going to make in two parts - now answered. But, forgive me for asking, I've a new question brewing: The drawing shows the clamping holes top and bottom, but none in the top-middle. I'd imagined this was because of the exhausts - but you have a hole in the middle. And yet your final picture shows exhausts - so why the holes?
Wilf
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