Polar Star Posted December 4, 2009 Share Posted December 4, 2009 Finney A4 - S7, 7mm scale 33mm gauge - A rivetting problem by polar star original page on Old RMweb __________________________________________ Comment posted by Horsetan on Thu Sep 24, 2009 4:23 pm alcazar wrote: I have to admit that I've never understood that part of the MRJ article, either. Also, there seems to be a circuit diagram, mentioned in the text for the reverser, missing from the article .............. I'll have to look into my copy of the said article. I don't remember seeing a diagram either. Maybe there wasn't enough space in the magazine issue. __________________________________________ ??? posted on Thu Sep 24, 2009 4:50 pm Horsetan wrote: alcazar wrote: I have to admit that I've never understood that part of the MRJ article. I'll have to look into my copy of the said article. Since posing the question some weeks back I have had the opportunity to see Bittern and take appropriate photographs. If you look at the first photo on the second page of this thread you can see the front face of the slidebar bracket... and the Ogee curve around the front bolt which secures the top slidebar. regards, Peter __________________________________________ Comment posted by PhilH on Thu Sep 24, 2009 8:48 pm One crank pin leads t'other pin by 120 degrees on each axle (an A4 has three cylinders) You might be interested to know that Gresley Pacific cranks are set at 120-113-127 deg. __________________________________________ Comment posted by Western Star on Thu Sep 24, 2009 9:02 pm PhilH wrote: One crank pin leads t'other pin by 120 degrees on each axle (an A4 has three cylinders) You might be interested to know that Gresley Pacific cranks are set at 120-113-127 deg. Thank you for this insight into the settings of the cranks on an A4, I hope that you do not mind my asking some questions about the settings. If we ignore the centre engine for the moment, what is the lead of the right hand crank pin over the left hand crank pin? How is the centre crank placed in relation to the right hand crank pin? I have not had the opportunity to look at the inside motion of Bittern as yet - might I assume that an A4 has divided drive and that feature leads to the requirement of unequal crank settings? Thank you, __________________________________________ Comment posted by alcazar on Thu Sep 24, 2009 10:03 pm Here's another question for the "techies" on here: can the 120 degree lead of crankpins be EASILY replicated with Slater's wheelsets, or are we stuck with non-prototypical 90 degrees? __________________________________________ Comment posted by dikitriki on Fri Sep 25, 2009 5:48 am alcazar wrote: Here's another question for the "techies" on here: can the 120 degree lead of crankpins be EASILY replicated with Slater's wheelsets, or are we stuck with non-prototypical 90 degrees? Hi Alcazar Very easily - you ask Slater's for a set of A3/A4 axles with 120 degree crank setting A word of warning though. If you have a fixed chassis they will work fine; I have found the running to be slightly less smooth on a fully compensated chassis. In fact I started off with 120 degree crank axles on my A3 and replaced them later with 'normal' Slater's axles. I must say, the Harris ones look magnificent though. Richard __________________________________________ Comment posted by Western Star on Fri Sep 25, 2009 7:59 am dikitriki wrote: A word of warning though. If you have a fixed chassis they will work fine; I have found the running to be slightly less smooth on a fully compensated chassis. In fact I started off with 120 degree crank axles on my A3 and replaced them later with 'normal' Slater's axles. Richard Hi Richard, I have often wondered if the use of a "normal / 90 degree" Slater's axle has any effect on the running of an A3 / A4 / V2 where the kit includes a working representation of the Gresley 2:1 lever arrangement. You are in a position to tell us... thanks Graham __________________________________________ Comment posted by Locomodels on Fri Sep 25, 2009 8:00 pm PhilH wrote: One crank pin leads t'other pin by 120 degrees on each axle (an A4 has three cylinders) You might be interested to know that Gresley Pacific cranks are set at 120-113-127 deg. However it is only the inner crank that is leading by 7 degrees. The wheels are set at 120 degrees with the right wheel leading.There is a really good set of photos of the wheels and crank axle on the Bittern web site. __________________________________________ Comment posted by PhilH on Sat Sep 26, 2009 11:57 am However it is only the inner crank that is leading by 7 degrees I think you'll find its set back by 7 degrees (isn't pedantry boring - I'll shut up now...) __________________________________________ Comment posted by Horsetan on Sat Sep 26, 2009 12:11 pm PhilH wrote: (isn't pedantry boring - I'll shut up now...) __________________________________________ Comment posted by dikitriki on Sat Sep 26, 2009 9:01 pm Western Star wrote: I have often wondered if the use of a "normal / 90 degree" Slater's axle has any effect on the running of an A3 / A4 / V2 where the kit includes a working representation of the Gresley 2:1 lever arrangement. You are in a position to tell us... Hi Graham I find that a difficult question to answer. Running, no, it runs fine whether you use 90 degree or 120 degree. If you mean visually, I haven't a clue. The movement of the outer valve spindles is of course exactly the same, and since you can't see both sides at once....... The inner valve spindle isn't that visible, but the movement in relation to the left hand side spindle (the more visible side) will be slightly different. I don't think I could tell the difference, but whether someone who knows the locomotive intimately could, I just don't know. I'm still impressed that it works nicely, at whatever setting! Regards Richard __________________________________________ ??? posted on Sun Sep 27, 2009 9:02 am alcazar wrote: Wow! How do you get the quartering spot on? Here are two photographs of the crank pin jig which was used for setting the crank pins on Merlin's wheels. The jig was made by Mr. Penn-Sayer, he retains the jig for use with his own wheels (he is a S7 modeller) and for wheels which he turns on commission. The first photo shows the jig arranged for wheels where the crank pins are at 90 degrees, as for two cylinder and most four cylinder engines. The steel / brass wedge on the desk is not required when the jig is setting crank pins at 90 degrees. This photo shows the jig arranged for wheels where the outside cranks are at 120-240 degrees, as for A3 and A4 engines. The wedges bolt onto the side plates to convert the jig for setting outside crank pins at 120 degrees. The jig can be used with 7mm wheelsets for either 32mm or 33mm track gauges. A wheelset can have either left or right leading crankpin with 90' or 120' setting. The flat plate on the top of the jig is used to drill the pilot hole, through the axle, for the taper pin which secures the two halves of the telescopic axle. The jig caters for different taper pin positions on the axle, for example:- gearboxes of different configuration/width, split insulation axles. The wheels in the pictures are for an Admas LSWR X6 4-4-0 which is being scratch built by Mr. Penn-Sayer. If you have any questions I shall try to provide answers. regards, Peter __________________________________________ Comment posted by alcazar on Sun Sep 27, 2009 9:36 am Many thanks for that, interesting pics. So, reading that, are you saying that Mr. Penn-Sayer sets the crankpins for you? If so, what do you do about removal/refitting of wheels, should it become necessary? Or do you then keep the wheelsets as pairs, and remove/refit the whole assembly, like the real railways did? And how easy are the wheels to push fit, given that the insulation material appears to be Tufnol, not exactly easily deformed, like, say, Nylon, as used on other push-fit wheels? __________________________________________ ??? posted on Sun Sep 27, 2009 11:40 am alcazar wrote: So, reading that, are you saying that Mr. Penn-Sayer sets the crankpins for you? If so, what do you do about removal/refitting of wheels, should it become necessary? Or do you then keep the wheelsets as pairs, and remove/refit the whole assembly, like the real railways did? And how easy are the wheels to push fit, given that the insulation material appears to be Tufnol, not exactly easily deformed, like, say, Nylon, as used on other push-fit wheels? Each wheel - bogie, coupled and Cartazzi - is on a separate stub axle. In the case of the bogie and Cartazzi wheels the stub axles are threaded and so bogie and Cartazzi wheel/stub axles are fitted / removed by a simple screw action. The driving axles are telescopic and the two parts are retained by a taper pin. The taper pins and associated reamer come from AGH - a taper pin can be seen on the desk in one of the photographs (as can a couple of crank pin screw caps). I do not need or wish to remove the wheels from the axles for each wheelset is made as an unit and when assembled gives accurate back-to-back measurement. This method of assembly has a bonus in that there is no "screw" visible in the wheel boss. __________________________________________ Comment posted by alcazar on Sun Sep 27, 2009 3:16 pm I see. What happens should you need to remove the driving wheels? __________________________________________ ??? posted on Sun Sep 27, 2009 3:43 pm alcazar wrote: What happens should you need to remove the driving wheels? Two options:- [1] draw the taper pin from the axle and remove each wheel sideways (where the axle runs in a bush soldered to the frames, this is as per the kit); [2] take down the break gear / springs, remove the hornstays and drop the wheelset / axleboxes (where the axle runs in axleboxes/hornguides, available as an option from Martin Finney). The Martin Finney design for the cylinders / slidebars / motion / reversing gear is such that those items can be removed as a single entity from the frames hence removal of wheels from axles (eg. Slater's wheels on square-ended axles) is possible. See the thread by Harrier-mate for relevant photographs. At this time I am building the engine with solid bushes and I shall replace those bushes with axleboxes / hornguides / hornstays at a later date. I just need to think through how to assemble the break gear and axlebox springs so that wheelsets can be dropped as per prototype. regards, Peter __________________________________________ Comment posted by 3 link on Sun Sep 27, 2009 3:55 pm alcazar wrote: I see. What happens should you need to remove the driving wheels? You find you have a lot of work ahead of you . Sorry I couldn't help myself Interesting thread by the way very detailed to say the least Regards, Martyn. __________________________________________ Comment posted by alcazar on Sun Sep 27, 2009 7:00 pm Peter: thanks for the informative responses. Please excuse my constant questions __________________________________________ ??? posted on Sun Sep 27, 2009 7:06 pm alcazar wrote: Peter: thanks for the informative responses. Please excuse my constant questions If you ask, we try to answer. Thinking about your questions of earlier today, I shall try to photograph a bogie wheelset and a driving wheelset so as to show how the axles are constructed. regards, Peter __________________________________________ ??? posted on Mon Sep 28, 2009 9:11 am Alcazar's questions about the wheels for my A4 lead me to think that RM Webbers might like to see how AGH wheels are assembled with telescopic axles, so here are some photographs. AGH wheels are supplied as "rough" castings and with a "solid" back, that solid back is removed in the turning process to leave separate spokes. A feature of turning the back away is that the spokes are left with a rag on the rear corners and that rag can be removed with files / emery boards. So far I have fettled the four bogie wheels and I am summoning the courage (nee effort) to start on the six driving wheels. In a previous post I mentioned that the wheels have some rust spots which is probably a consequence of the flux fumes, this is visible in these photos. The current condition of the wheels is my fault and not that of Mr. Penn-Sayer. The wheels were nice and shiny when I received them and I had them on the shelf, above the soldering iron station, so that I could admire the appearance. The first photograph shows a complete and assembled wheelset, the taper pin is as supplied by AGH and shall be trimmed after Merlin has moved under its own power. For those who cannot spot the join between the stubs, the join is adjacent to the Tufnol bush on the RHS wheel. Also visible in this photo are the crank pins which are supplied by AGH (fitted during the wheel turning process so as to provide the necessary registers for setting the crank pins - please see the posting on the crank pin setting jig). The next photo shows a wheel and stub, actually the male stub axle. The orange material is Tufnol, supplied by AGH, and provides the insulation between the wheels. VIsible in this photo is the rag on the rear of the spokes. You may be able to see that the rag is only on one corner of each spoke, that is the edge where the cutting tip leaves the spoke. In fettling the spokes I shall round of the rear corners of the spokes and blend the spokes into the boss and rim. This photo shows the three separate parts of a wheelset. The axle is made in two parts with a telescopic joint between the two parts, the axle is held together by a taper pin (lying between the wheels). The wheel on the left has the female stub axle and the wheel on the right has the male stub axle. The holes for the taper pin are visible - as is the taper on the pin - which requires a taper reamer for the correct fit of pin in the hole (AGH supplied the taper reamer and the taper pins). The production of these wheelsets was not done by me - I am grateful for the contribution of my friend, Paul. regards, Peter __________________________________________ Comment posted by OgaugeJB on Mon Sep 28, 2009 10:22 am S7 - 33mm gauge! Good man! Are you going to Wells this weekend ? JB. __________________________________________ Comment posted by alcazar on Mon Sep 28, 2009 10:52 am Thanks again Peter, all is now clear. Am I right in thinking that Mr.Penn-Sayer also makes the axles, sets the crankpins to your choice of lead angle and drills for the rollpin?Or do you have to borrow the jig and do that bit yourself? Do you want to say how much his services cost?? It may have occurred to you that I'm slowly but surely working out the price differential between Slater's and AGH, so I can see a) if I think it's worth it, and B) if I can afford it. __________________________________________ Comment posted by OgaugeJB on Mon Sep 28, 2009 11:14 am alcazar wrote: It may have occurred to you that I'm slowly but surely working out the price differential between Slater's and AGH, so I can see a) if I think it's worth it, and B) if I can afford it. It IS worth it I think, although you will need to re-mortgage the family home and wait a while to get them ! I use re-profiled slaters wheels and then with a very sharp scalpel take down the corners on the rear of the spokes. Although they won't look quite as nice as the AGH because of the dirty great screw in the middle, they do look a lot better and far more delicate than if you slap the slaters wheels on straight from the packet... JB. __________________________________________ ??? posted on Mon Sep 28, 2009 12:13 pm alcazar wrote: Am I right in thinking that Mr.Penn-Sayer also makes the axles, sets the crankpins to your choice of lead angle and drills for the rollpin?Or do you have to borrow the jig and do that bit yourself? Do you want to say how much his services cost?? It may have occurred to you that I'm slowly but surely working out the price differential between Slater's and AGH, so I can see a) if I think it's worth it, and B) if I can afford it. The wheels for Merlin were done at the same time as several other engines, for example the LSWR X6 which is shown in one of the photos that I posted yesterday. Hence the "order" to AGH included AGH crank pins, Tufnol rod, steel stock for axles and taper pins to cover several engines - all of which were supplied by AGH to Mr. Penn-Sayer. The work to produce a wheelset included:- * turning the castings to the required tyre profile; * insulating all wheels at the boss and driving wheels at the crankpins; * fitting crank pins, (note AGH supplies crank pins in two lengths); * making the axles (telescopic or screw as appropriate); * mounting each wheel on the respective stub axle and setting the wheelset to gauge (for 32mm or 33mm track as required); * setting crank pins at required lead and then drilling axles for taper pin. I did not need to use the jig for Merlin's wheels were supplied complete and fully finished - ready to fit into Merlin's frame. You made mention of roll pins in connection with the telescopic axles. A roll pin is like a split tube and might work, I suspect that such a pin would be difficult to fit and even more difficult to remove. Paul drills the hole in a "assembled" axle using his jig (see previous post) and then reams the hole to the correct taper for the AGH taper pin (probably 1:48 taper) - when a taper pin is inserted into the axle hole the pin is loose up to the moment when the surface of the taper pin touches the internal surface of the axle hole throughout the depth of the hole where upon the pin goes tight. The pin is removed from the axle by a light tap on the small end of the pin where upon the pin comes clean from the internal surface of the axle hole and drops out. By the way, this is how railway companies dealt with the pins in the motion work for their 12" to 1' modelling. Please understand if I do not comment on the matter of price here. I am pleased with the result and I shall use the service for my next engine. I can provide contact details via PM if you wish. The question as to whether or not to use AGH is a personal choice and must take price / availability / appearance into account. There are some people who say that AGH wheels improve running and I have yet to decide on that matter. Wheels for an A4 can be obtained from several suppliers, be that finished as per Slater's products or castings as per AGH and possibly Walsall. My choice was driven by appearance of the spokes and boss. In passing, I am building some other 7mm engines and those have Slater's wheels (tyres reduced in width and reprofiled to S7 standard), in those cases the Slater's wheels have an acceptable appearance. You might like to ask Richard Lambert for his opinion of AGH versus Slater's wheels for his FInney A3 as I understand he is demonstrating at the Peterborough show in October. regards, Peter __________________________________________ ??? posted on Mon Sep 28, 2009 12:28 pm OgaugeJB wrote: S7 - 33mm gauge! Good man! I use re-profiled slaters wheels... Although they won't look quite as nice as the AGH because of the dirty great screw in the middle... JB. How polite of you to not comment until I changed the title of the thread. You did, of course, recognise the S7 profile of the wheels when posted earlier and the delicate appearance of the S7 GWR track panels... or was the mention of the GWR too much? Here is the photo again... Yes that screw, one of the major reasons why I have used AGH for Merlin. regards, Peter __________________________________________ Link to comment Share on other sites More sharing options...
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