PhilMortimer Posted March 16, 2018 Author Share Posted March 16, 2018 (edited) IT all sounds fantastic! I've never learnt CAD, so this is all fascinating to me. I understand about the radius ends to the slots, but that shouldn't be too much bother to square up. A few questions, 1) what is a 10% dogleg and how does it work? 2) Since this is now all in CAD, will you be doing the coupling rods to ensure they fit accurately? 3) Since you're on a roll, are you intending to model the rest of the loco and release it as an accurate kit! Started trial fitting the expansion links last night - picture to follow. trying to work out a method of fitting the link to allow it to be removed for painting. At the moment, it is all held together with a 14BA bolt through the entire link, which actually isn't that obvious, but annoys me,,,,,,,, Must try harder. But too damned knackered to progress it too far. However, I did confirm that I'm going to have to do something about the Radius rods, as they appear to be slightly too long and so are jamming the motion..... Edited March 16, 2018 by PhilMortimer Link to post Share on other sites More sharing options...
Simond Posted March 16, 2018 Share Posted March 16, 2018 Hi Phil, Giles’ dogleg is a Very Good Idea. Better even than a cunning plan. The cutters I have are 1mm, 39.35 thousandths of your bog standard imperial inch, and the brass I will have is 36 thou. So assuming the cutter cuts to size (and my guess is that it will be over, by a little bit, but I have no clear idea how big a little bit???) the slot will be 3-5 thou wider than the tab that goes in it, so sloppy. The idea is that instead of cutting a straight slot, I cut a slot with a kink (or multiple kinks) in it. The sides of the kink will then be tight on the tab that gets pushed in, and the assembly will be “snug” before I solder it up. A bit of trial slot milling will enable me tune the offset in the kink for that Goldilocks fit. Various designs of “kink” are possible, to push the tab to one side or the other. The free space between the tab & slot will allow the solder to flow, so it’s a win-win. Very helpful suggestion, and blindingly obvious, now . As Huxley remarked, how very stupid of me not to have thought of that. Thanks Giles! I’m copying this lot over to my loco loco thread to have the story in one place, Best Simon Link to post Share on other sites More sharing options...
PhilMortimer Posted March 16, 2018 Author Share Posted March 16, 2018 OK, now I get it. Very smart idea! Following this on both threads now! P Link to post Share on other sites More sharing options...
PhilMortimer Posted March 16, 2018 Author Share Posted March 16, 2018 And a picture of one of the power units with the first expansion link fitted. . by Phil Mortimer, on Flickr Pivot is temporary with a 14BA bolt passed through the trunions. Need to sort that out. Also, the radius rod is disconnected as detailed above to check the action of the expansion link, which waggles away quite satisfactorily. Link to post Share on other sites More sharing options...
PhilMortimer Posted March 21, 2018 Author Share Posted March 21, 2018 (edited) The first day of Spring arrived yesterday here in Maryland..... Spring_Snow1 by Phil Mortimer, on Flickr . by Phil Mortimer, on Flickr Spring_Snow3 by Phil Mortimer, on Flickr . by Phil Mortimer, on Flickr WE are expecting an additional foot today, so that means that I can probably expect to be exercising the snow thrower this evening... Whilst the roads are sort of passable, the snow has pretty much shut everything down and no-one is going anywhere for the duration. Even work has been closed for the past two days. This has its advantages as it means that I had a full day on the garratts yesterday, and all the expansion links are now fitted. The job involved carefully soldering a small nut tapped 14BA to the inside of the outer expansion link bracket in order to space the expansion link from the bracket and to retain the 14BA bolt used as the pivot. The soldering was quite involved and the preperation had to be done in the correct order, but otherwise, there was nothing special. The spacer was made from a 16BA nut, drilled out and tapped 14BA. This size nut was chosen for its small size to make it as unobtrusiveon the bracket as possible. At present, the pivot bolt goes right through the expansion link to the far side bracket, but eventually it will be cut back and the innerside will have a permanent pivot soldered to the expansion link trunnion. The screw in pivot ill just then support the outer side of the expansion link. It sounds complex, but makes sense when seen. One may ask why the complexity and yes, the VG could have been soldered and pinned together. But I want to be able to take down the motion for painting, and this is the best way I can figure on doing it. The last part of the main VG is now to connect the radius rods to the expansion link and check it all works smoothly. May be a job for today with this snow and my enforced day off....... Edited March 21, 2018 by PhilMortimer 4 Link to post Share on other sites More sharing options...
Simond Posted March 21, 2018 Share Posted March 21, 2018 I’m not seeing a huge sympathy vote... Link to post Share on other sites More sharing options...
PhilMortimer Posted March 21, 2018 Author Share Posted March 21, 2018 That's ok. It was an unexpected benefit and unexpected progress on the Garratts! Work gets enough unpaid overtime out if me anyhow, so I don't feel particularly bad about it! Link to post Share on other sites More sharing options...
PhilMortimer Posted March 23, 2018 Author Share Posted March 23, 2018 Back to it. Started amending the radius rod, so that it doesen't jam when in motion. Removed the rod from the combination lever and reformed the yoke at that end - much more U shaped now. Did the same thing at the expansion link end, but it is far too wide. Even then, the rod is still too long and the whole lot jams when in motion. Will probably need to shorten the rods slightly, but want to mull this over a bit more first on best how to do so. The rods are tapered, and also have a kink in them at the expansion link end between the pivot from the drop link and the expansion link joint.So any modifications need to be done carefully in order to keep the geometry correct and avoid moving things too much. Need some thinking time. Link to post Share on other sites More sharing options...
PhilMortimer Posted March 26, 2018 Author Share Posted March 26, 2018 (edited) Quick update. I lost a little bit of my Mojo over the past few days, due to the difficulties with making the valve gear work without jamming. The problem was trhat the rod was too long and jamming against the end of the valve guides at some point in the stroke. In the end I left everything for a few days and dealt with other matters unrelated to railways, garratts, or such like. As it turned out, this helped and last night I got back to it. To cut a long story short, I concluded that the only way to proceed would be to shorten the radius rod by a couple of mils. However, this would be a point of no return and I made up a test rod from some scrap etch to check the new dimensions would work, which they do. That done, I used this to set up a jig (a couple of pins knocked into some wood to set the correct pivot spacing),then removed the fork at the valve end of the rod. The now blind end of the rodf was drilled (carefully) and reshaped to make a new fork, and the fork pivots resoldered onto the outside of the new fork and blended in. This re-inforces the new pivots, as there ins't a lot of metal present in the rod at that point. test fitting shows that everything works. I now need to re-attach the rod permernantly to the combination lever and clean everything up. And then amend the remaining rods. Photo's to follow, but we're on a roll again! Edited March 27, 2018 by PhilMortimer 3 Link to post Share on other sites More sharing options...
PhilMortimer Posted March 27, 2018 Author Share Posted March 27, 2018 (edited) Yesterday evening was one step back before one step forward again. Having adjusted the radius rod and gottten everything working, I then proceeded to completely solder everything solid when re-pinning it to the combination lever. Lots of blue language and several hours later, after taking everything apart and cleaning it all up, everything works fine now, But I wasn't happy with myself. So I didn't get any others done last night. I don't think the shorter rod is going to be significantly noticable. It is a nessecary compromise to get a smoothly working loco and I can live with it. I'm not sure why the original length rod jams - it an al the other rods match the dimensions in the GA. I think it might be something to do with the relative position of the motion vs the axle positions of the kit (I had to adjust the inner axle positions slightly when using the coupling rods to install the axle bearings. However, now I know what I need to do, hopefully the remainder will get done much faster. P Edited March 27, 2018 by PhilMortimer Link to post Share on other sites More sharing options...
PhilMortimer Posted March 29, 2018 Author Share Posted March 29, 2018 Getting in the swing of things now - so much so, that I've just made a replacement rod to replace the first one I did, which is a little short for my liking! Link to post Share on other sites More sharing options...
PhilMortimer Posted March 30, 2018 Author Share Posted March 30, 2018 Still working on it - replacement rod (the one i scratched up from scrap etch) fitted last night - looks (and works) much better. 3rd rod prepped and ready for install tonight. Other life things have been getting in the way. 2 Link to post Share on other sites More sharing options...
PhilMortimer Posted April 2, 2018 Author Share Posted April 2, 2018 (edited) I have now completed the radius rods for the four sets of valve gear on the front engine units and thus far all sets of VG operate smoothly. I ended up shortening the radius rods by a few mm so they would not jam in the motion cycle. This basically involved remaking the forks at making the expansion link end so that there was sufficient room for the expansion link to pivot unimpeded at the furthest end of its travel, and shortening the rods by removing the existing pivot points at the combination lever end and making new pivot points. Again, sufficient room must be present for the combination lever to move within the radius rod yoke during the oscillation cycle. A scrap piece of etch was used to test the new length between the radius rod pivots was correct when fitted to the valve gear, and that all functioned correctly. This is shown temporarily fitted in the picture below using brass wire pins. Everything worked just fine. . by Phil Mortimer, on Flickr To make sure everything worked, the valve gear was set at Full Gear for testing. This gives the maximum movement of the radius rod and the greatest chance of jamming. Reducing the cut off will give reduced radius rod and valve rod movement and so if the VG works in full gear, it will work at a lesser cut off. To hold the expansion link end of the radius rod in the Full Gear position, a small piece of tube is temporarily soldered into the expansion link to act as the pivot point, allowing a pin to be slipped through the rod and the tube and holding the rod at the correct full gear cut off position. This can be seen in the photo below, together with the modified radius rod and the temporary one used to check the pivot spacing, . by Phil Mortimer, on Flickr The expansion link tube will be removed once the lift and drop links are installed and a free floating piece of tube installed to act as the die block. However, at this stage, I wanted to get the VG working without worrying about the influence of the droplinks. This will also allow the VG to be positioned at a more appropriate cut-off. Once everything was checked with temporary pins and free-moving operation was achieved, a permernant soldered pinned joint was made to reconnect the radius rod to the combination lever. At this stage, I don't have a video of the full operation, but the following set of four picture should illustrate the full operation of the VG as the wheel rotates one full revolution. . by Phil Mortimer, on Flickr Crank at Bottom dead Centre - Valve rod forward. . by Phil Mortimer, on Flickr Crank at full rear position - Valve rod moving back . by Phil Mortimer, on Flickr Crank at Top Dead Center - Valve rod pulled back . by Phil Mortimer, on Flickr Crank in Forward position - valve rod moving forward again. Once I have the motors and gearboxes in, I will obtain some video of the operation of the valve gear. It is quite mesmersing and I'm pleased that it is finally coming together. Next up is fitting the radius rods to the rear units. In this case, these will be in the down position, as they will be operating in the opposite direction to the front units. Again, modification of the rods is going to be needed, so there will be some time-consuming work involved. I can't remember which way the up / down movement of the radius rods influences the direction of travel, but I think that the front units are currently set in reverse! Once all sets of VG (front and rear) are working, the lift and drop links will be re-installed, and the VG position adjusted to give a smaller more realistic movement. (Though as industrial locos with short journeys, often on steeply graded lines, it might be expected that these loco's probably spent much of their lives in full forward or full reverse gear!). Have to say, I feel pretty pleased with myself that it is starting to come together at last! Edited April 2, 2018 by PhilMortimer 2 Link to post Share on other sites More sharing options...
Giles Posted April 3, 2018 Share Posted April 3, 2018 Glad you've sorted it! Yes, that engine is in reverse as shown. Correct for fifty percent of the time! Link to post Share on other sites More sharing options...
Simond Posted April 3, 2018 Share Posted April 3, 2018 or fifty percent of the engines... Simon Link to post Share on other sites More sharing options...
PhilMortimer Posted April 3, 2018 Author Share Posted April 3, 2018 (edited) I might switch them around at the point of final assembly, whereby the front engine is set in the forward direction and the hind unit is set for rearwards movement. There is no eartly reason to do this, since as Giles points out, these loco;s are likely to be going backwards as much as forwards. However, I like the idea of a loco set in the forward direction, even though there is no reason for it! Of course, that might change by the time we (eventually) get to finishing them!. Or I could revisit that idea of fitting the servo's to actibate the reverser..... Edited April 3, 2018 by PhilMortimer Link to post Share on other sites More sharing options...
PhilMortimer Posted April 6, 2018 Author Share Posted April 6, 2018 Sorry for the lack of updates - my feline assitant / co-conspiritor has been very sick, having had to have emergency surgery last Saturday, and the evenings have been spent visiting him. First night home last night, so hopefully improvements will follow and we can get back to normal. Link to post Share on other sites More sharing options...
Simond Posted April 6, 2018 Share Posted April 6, 2018 Sorry to hear about the cat. Wish him/her a speedy & full recovery! Engines are looking good. My CAD is coming along glacially at the moment, but the Duchess is progressing. Best Simon Link to post Share on other sites More sharing options...
Giles Posted April 6, 2018 Share Posted April 6, 2018 Extremely sorry to hear that - I do hope that he gets better quickly- we list our (feline) girl to cancer last year, and we were devastated, so I sympathise greatly. Best wishes G Link to post Share on other sites More sharing options...
PhilMortimer Posted April 9, 2018 Author Share Posted April 9, 2018 (edited) Thank you both for your kind thoughts. Stew is still in recovery and not out of the woods yet. But this morning's checkup was positive. He spends his day recovering as seen below.... Sleepy Sewart by Phil Mortimer, on Flickr In the meantime, since he can't get to my workbench to wreck it, I have been using the quiet time to carry on working with the hind unit valve gear. I just have two more radius rods to modify now. I have discovered that Gibson 4mm scale small valve gear bushes are almost a direct fit in the expansion link slot, so may well act as the die block. Work continues. Simon, I'm envious of that Duchess..... Edited April 9, 2018 by PhilMortimer 3 Link to post Share on other sites More sharing options...
PhilMortimer Posted April 12, 2018 Author Share Posted April 12, 2018 All radius rods are now modified. I am at present working on the rather complex task of determining and marking out where the lifting link weigh-shaft passes through the frames, so that I can fit the lifting and drop links. There is no marking on the frames for this and determining a fixed reference point is proving to be a bit tricky. It would of course have helped if I'd thought of this earlier whilst the frames were still in the flat. A case of the 5 P's (Proper Planning Prevents Poor Performance!) Much studying of the GA plans is currently being undertaken, Stewart continues to improve. 1 Link to post Share on other sites More sharing options...
Simond Posted April 12, 2018 Share Posted April 12, 2018 Phil, I might be able to help as I’ve copied the GA into TurboCAD, and scaled it to known measurements. It’s on my work computer, so it’ll have to be tomorrow. Best Simon Link to post Share on other sites More sharing options...
PhilMortimer Posted April 12, 2018 Author Share Posted April 12, 2018 Thanks Simon, I was just too tired to do it last night - the risk of getting it wrong was too high. Hopefully, tonight, i can get a better look at things. However, I may well avail myself of your measurements as a double check. Many Thanks, P Link to post Share on other sites More sharing options...
Simond Posted April 12, 2018 Share Posted April 12, 2018 Hoping I get 5 minutes as I can’t hang around after, booked in for new tyres... on the car! Will try, promise! S Link to post Share on other sites More sharing options...
Simond Posted April 13, 2018 Share Posted April 13, 2018 (edited) can't copy past a jpg into the thread... hope this attaches ok - I measure 5.56 down from the frame top, and 20.27 back from the front axle have emailed myself the TCW so I can open it at home over the weekend if you want to check anything else best Simon Edited April 13, 2018 by Simond Link to post Share on other sites More sharing options...
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