Lisa
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Posts: 806
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Post by Lisa on Dec 21, 2018 21:51:14 GMT
That's the left side done, and the valves set, I just need to pull it apart and do the other side. The valve timing was a long-term worry, as the eccentrics and collars were done by 'impatient younger me'... but once I got the timing right in forward motion, slipping her into reverse showed that was spot on too, with the ports just cracking open at the dead centres, so that's a relief. Now I just need to repeat it all on the right side, and sort out that motion bracket. Then solder a 1/4BSP thread onto the main steam pipe so I can connect it all the the compressor.
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Lisa
Statesman
Posts: 806
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Post by Lisa on Dec 21, 2018 6:45:37 GMT
Good on you Lisa for having a go at finishing the Blowie.Just try to keep in mind that simple locos like this are very forgiving and will work ok without being a precision job. you are going great and i am sure that the finished engine will run well. Don't try to make everything to tight a fit as it is a recipricating engine with a floating crankshaft.a few thou clearance here and there works wonders. I have made 14 of them so am not totally inexperienced.I have seen one built by a bricklayer and it was built with the same tollerances that he lays briks and it was abit rough but ran OK. My general aim is to be as accurate as I can where I can, and just make it work where I can't. Mostly this just involves working with younger me's impatience. But as you say, she should run well enough once done. Anyway, I did a bit this morning, and one piston rod is now the right length. It occurred to me that I need to shorten it by 6mm, and the thread in the piston is 6mm long; so I just unscrewed the piston, chopped the threaded bit off, and cut a new thread on the lathe. Once the piston was back on it all went fine, and one side is now able to turn a full revolution without banging against the cylinder ends, so I'll do the other side the same way. No pic's, as I was racing the heat this morning (39°C today!); but if all goes well I should be setting the valves soon.
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Lisa
Statesman
Posts: 806
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Post by Lisa on Dec 20, 2018 11:42:25 GMT
My brother and I were always at complete opposite ends of the spectrum (in life as well as driving, but never mind).
He would keep the fire stacked to the bottom of the door, maybe a bit higher. Always used the axlepump, or hand pump, and practically never used the injector. Would not get underway till the safeties had lifted, and always ran in full gear. He only fired when stopped at the station; he'd rake the fire half to death then pile more coal in.
On the other hand, I kept the fire thin (and on some occasions deliberately fired a hole in the fire, so as to keep the safeties from lifting). Used the injector almost exclusively, usually on the run (likewise, usually firing on the run). I'd be happy with anything over 60 on the clock and would bring the reverser back two notches once underway.
Taking over from my brother it could be 15 minutes or so before I'd even touch the fire sometimes, just letting it burn down. Meanwhile he'd get in a grumpy panic if I handed over to him with anything less than 90psi.
Dad though was somewhere in the middle; he ran a light fire like me, but preferred the safeties to lift before getting underway. He'd use the axle pump, but top up with the injector when needed. Sometime he'd notch up, sometimes he wouldn't.
We were a mixed trio, but while I'd grump at dad and my brother for wasting water with the safeties blowing off, dad'd grump at my brother about the cost of coal, and my brother would grump at us for the fire being almost out(!?), ultimately we all got the job done, and with our little loco's there isn't that much difference in coal and water usage.
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Lisa
Statesman
Posts: 806
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Post by Lisa on Dec 18, 2018 22:01:16 GMT
Nice loco, shame about the racetrack speeds.
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Lisa
Statesman
Posts: 806
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Post by Lisa on Dec 17, 2018 23:29:55 GMT
I finished putting the printer together last night, and after a bit of frustration trying to get Cura to work I eventually discovered I'm not the only one having problems with that program (unusable was mentioned by some) and got a test print running using Pronterface. There was a guide wheel missing from my kit, but rather than chasing one down through distributors etc. I just bought a pack of 10 off ebay for a few dollars; so I now have a heap of spares. Other than that though, it all went together well, a few fiddly bits, but all of the parts fitted as they should. So having discovered that Cura pretty much doesn't work at all over USB at present, I switched to Pronterface and things worked much smoother. Ultimately the print failed, but I learnt a lot in the process, and I'm sure subsequent prints will go much better. The test print I used was a small box not much bigger than a business card; it's one of the files that came with the printer. I only got as far as printing the bottom of it, before the whole thing came unstuck from the print bed; which was unsurprising given how poor the print quality was at the beginning. Here's the bottom of the bit I got done, showing how things started out. It's Bad. Individual lines of PLA that aren't stuck together, and weren't sticking to the bed either. Fortunately, Pronterface let me adjust setting while the print was running, which is perfect for experimenting. So after a bit of messing about, I increased the extrusion speed, slowed down the movement of the print head, and increased the bed temperature a little. The results were much better: You can see here the point at which it came unstuck from the bed, and the job moved, at which point I canceled the print. However the quality of the print is significantly improved over the first photo', with good solid extrusions, and everything connected together as a single piece as it should be. So this is looking good for future experiments.
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Lisa
Statesman
Posts: 806
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Post by Lisa on Dec 17, 2018 2:23:18 GMT
Hello everyone, I've just been chatting with some auld pharty bagz I met down the Pub called "4930Hagley" and he tells me that when he haunted these hallowed threads you could change the Green wallpaper to a light Blue and with that came Black characters on a white desktop.....Much easier on the eye, allegedly !! But time and age have taken their toll and he can't remember how it's done !!... (or afford a pint either ) Anyone know how it's done ?? If you click on 'Profile' at the top of the page, then 'Edit Profile' on the right, then 'Settings' on the left, you'll see a little drop-down box labelled 'Forum Theme'; you can change the way the forum displays there, there's a few options.
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Lisa
Statesman
Posts: 806
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Post by Lisa on Dec 16, 2018 9:52:18 GMT
Nothing, too wet, too cold, too horrible, hybernated! D Come to Oz, too hot, too dry, too dusty and now too windy. Jim.
It's been that "delightful" mix of both warm and raining here, have had the air conditioner running in dehumidifier mode to make the house livable.
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Lisa
Statesman
Posts: 806
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Post by Lisa on Dec 14, 2018 12:29:48 GMT
Hi Brian, pretty sure the piston rod length is just me miscalculating things when I changed the way the piston rod is fitted to the crosshead. The cylinder cutouts in the frames - which are the likely cause of one motion bracket being higher than the other - were not entirely done as a matched pair, so therein lies the problem. As I said, impatient teenage me not making the best of decisions.
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Lisa
Statesman
Posts: 806
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Post by Lisa on Dec 14, 2018 7:13:15 GMT
One would hope those holes in the piston are blind!
That's quite a neat sounding arrangement Adam, I'll have a look into it, ta.
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Lisa
Statesman
Posts: 806
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Post by Lisa on Dec 14, 2018 3:06:31 GMT
We tried this a while back; the result was that while the tread and flanges will wear with fixed wheels, with one loose you end up with worn treads, flanges, axles, and axle holes! Which makes for considerably more maintenance than just fixing both wheels to the axle, as you can't just do a quick reprofile.
However, on passenger carrying stock we ended up going with rigid axles locked to the bogie frames, with each wheel having its own roller bearing(s) and rotating around the fixed axle. This did give a significant reduction in wear.
So, if you want the wheels loose on the axle, design it that way from the beginning and use roller bearings, don't just leave a wheel loose; unless you particularly want a maintenance headache.
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Lisa
Statesman
Posts: 806
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Post by Lisa on Dec 14, 2018 2:52:51 GMT
If it's only 2mm, could you recess the end of the Piston or undercut the end of the thread? Maybe you don't need the thread to be that long? It needs to be shortened by 6mm, then there'll be 2mm of clearance at each end. The piston is already only threaded for half its length, the other half being a tight sliding fit on the piston rod, so there's not enough thread there to do this at the piston end. Could you bore the crosshead 2mm or so for the Dia of the piston rod itself? that way you aren't weakening the piston rod removing the thread and can screw up hard on a shoulder with support around it? I could, but I'd wanted to make a thin nut to go on the piston rod; which would both act as a lock nut, and would simplify pulling things apart without having to clamp onto the rod itself. Also, as mention above, it needs to move by 6mm (which would still leave a good 14mm or more of thread in the crosshead), 2mm is just the clearance at each end of stroke once it's in the right place. If I skip the nut I could certainly do this though. Looking forward to seeing this turn a wheel Lisa! As am I! Though I was rather pleased that turning them by hand as far as they go, it all had a rather nice 'tight but smooth' feel to it. At least it should be easy to measure how much you need to shorten the rod by. Unless you were trying to get it spot on by measuring beforehand I think a long piston rod is pretty normal. It's about 6mm, give or take a half. Certainly better long than short I'd say! What did you do about the crosshead bracket being out of place? At the moment, nothing. I'll probably just make a new motion bracket that's a little shorter, and put up with things not being the same each side; I suspect this is a remnant of the impatient teenage me that put the frames together. One cylinder is just a little higher, and more angled, than the other. It's not like it'll have any knock-on effects to the valve gear, slip eccentrics are rather forgiving. If I wanted to get it right, I'd likely end up replacing the frames (and wow would I do those differently to the plans if I went down that path!). Thanks.
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Lisa
Statesman
Posts: 806
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Post by Lisa on Dec 13, 2018 15:12:17 GMT
I have, yes; there should be about 2mm clearance at each end once it's in the right spot. I'm going to need that M8F die now though, as I don't fancy trying to extend a thread with screwcutting on the lathe!
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Lisa
Statesman
Posts: 806
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Post by Lisa on Dec 13, 2018 12:11:53 GMT
Next on the 'oh bugger' list, it seems I need to shorten the piston rods:
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Lisa
Statesman
Posts: 806
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Post by Lisa on Dec 12, 2018 14:32:59 GMT
If you look back in my Blowfly thread (the first few pages), you'll see how I made my coupling and connecting rods; in 3 pieces silver soldered together, which greatly reduces the amount of work when you don't have a mill (or, for that matter, even if you do!). There's also some pic's of my rather rough but functional adjustable coupling rods, for getting the centres right and drilling the crankpin holes.
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Lisa
Statesman
Posts: 806
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Post by Lisa on Dec 12, 2018 13:37:21 GMT
Well, if we're posting pic's to show we've done it, here's one of 7 year old me in the back yard: And about 10 years later: Not particularly good photo's, and there's nothing more recent; both because I'm good at hiding from the camera, and because it's been a while.
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Lisa
Statesman
Posts: 806
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Post by Lisa on Dec 12, 2018 10:35:11 GMT
Lifting the frames up did the job on the tricky hole, though I also had to use the collet chuck to get few extra millimetres of height. The base of the mill is slightly tapered, so lifting the frames up meant I could move them over just a little further, which was just enough to get the hole under the drill. The other side wasn't a problem, as the handedness put the hole at the back rather than the front, and I could just turn the frames to an angle across the x/z axis that gave the few extra millimetres without needing the packing.
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Lisa
Statesman
Posts: 806
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Post by Lisa on Dec 12, 2018 3:02:59 GMT
If you hold control and press F5 it will clear your browser's cached version of the page and force a reload, doing that when you have issues should clear them up.
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Lisa
Statesman
Posts: 806
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Post by Lisa on Dec 11, 2018 11:46:56 GMT
Ah, I assumed that lifting the buffer beam up onto the mill base meant that you ran out of height with the chuck you've got and that you might still be able to do it if that was shorter. I hadn't thought of lifting the frames up as there's not a lot of height to spare as it is; but while lifting the buffer beam up on top of the mill table won't work (even with a completely flush collet, there's not enough room there to have the cylinder in place to spot the hole through), it might be possible to lift the frames maybe 20-30mm which, given the shape of the mill base, might gain the few extra millimetres of table travel needed. Or maybe even spot the hole with a punch, then drill it with the frames lifted and no cylinder restricting the height. I'll do the other side while I ponder that, ta.
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Lisa
Statesman
Posts: 806
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Post by Lisa on Dec 11, 2018 9:32:34 GMT
The length is fine Roger, I just can't move the table over to align the drill with the hole as the bufferbeam's up against the base of the mill.
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Lisa
Statesman
Posts: 806
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Post by Lisa on Dec 11, 2018 8:09:50 GMT
By the time I'd thought of (or heard of!) clupet rings I'd already bought the regular type, but they're certainly something I'd consider in the future. Meanwhile, I've drilled and tapped four of the five bolting holes for the left cylinder, but this one isn't going to happen as the buffer beam is now hard against the mill base... I'll see if I can wangle it in under the bench drill somehow, otherwise it'll have to be done with the pistol drill. It might be possible to spot through with the pistol drill then drill properly on the bench drill with the cylinder out of the way... we shall see. I'll do the other side first.
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