johnhale
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Post by johnhale on Jun 4, 2021 4:11:27 GMT
Excellent work as always
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Post by Roger on Aug 7, 2021 19:32:32 GMT
It's been a while since I've done anything towards the Locomotive, and to be honest I needed a break after 7 years of near daily updates. The Milling machine is still a work in progress, so at the moment I'm back with Mach4 while I sort out the issues I caused when shorting out the new controller. However, today I've picked up and outstanding job that needed making, namely the Lubricator boxes on the Valve Crosshead. Here's a reminder of what those look like. If you recall, I experimented with the plumbing to make sure I could make viable connections to these. 20180110_134225 by Georgia Montgomery, on Flickr The boxes are being made from Colphos since the originals would probably have been Bronze. Brass can look a bit too yellow in my opinion for this sort of thing. The key to CNC machining something like this is an accurate setup. The spindle needs to be on the centre of rotation of the 4th axis else it's going to end up with an offset between the sides when I machine them. The first operation creates the general shape, including the fillet where the lug meets the body. That's done with 3D parallel finishing. The fixing holes are added at this stage too. 20210807_124159 by Georgia Montgomery, on Flickr Then it's flipped over on its side for the inside operations. This is where the dead stops come in handy. This type of tilting rotary table doesn't have them, so you normally have to clock it up each time you move it. 20210807_125914 by Georgia Montgomery, on Flickr The inside is rouged out with a 3mm cutter... 20210807_144959 by Georgia Montgomery, on Flickr ... then finished with a 1mm PCB burr. PCB cutters always have long flute lengths, usually 10mm, so they can reach through a stack of 4 x 1.6mm FR4 PCBs. I think this is likely to change at some point, because the reduced sizes of holes mean that most manufacturers only run three boards high. That's because the flute length on small drill sizes isn't sufficient to reach through four boards. 20210807_150007 by Georgia Montgomery, on Flickr Fortunately the M2.5 exit holes can be drilled and tapped from the top. 20210807_153032 by Georgia Montgomery, on Flickr The 4th axis was then set over to 90 degrees and the 0.6mm pivot hole drilled. It's not possible to reach right through, so the 4th axis was turned to -90 degrees to do the other one. This is where you see if you've set it up accurately enough! 20210807_153743 by Georgia Montgomery, on Flickr Then it was just a matter of parting it off a little over length and tidying up the back with a file. 20210807_154527 by Georgia Montgomery, on Flickr Here's the second one getting the tool set up to the correct depth. I've turned the OD to make it easier to clock it true on the 4th Axis and to find the centre. I just measure the diameter of the turned part and halve it. That becomes the Z-axis DRO setting. The job has be defined in the CAM so that the centre of rotation of the 4th axis is X0Y0 in one plane and the end of job is zero in the orientation shown below. 20210807_182410 by Georgia Montgomery, on Flickr So here are the first two, I'll make the others before machining the lids. 20210807_195947 by Georgia Montgomery, on Flickr They aren't very big, but will still hold a useful amount of oil to lubricate the crosshead. 20210807_200026 by Georgia Montgomery, on Flickr
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Post by jon38r80 on Aug 7, 2021 21:05:53 GMT
Good to see you back at work on something I can understand. More like fine jewelery than engineering.
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Gary L
Elder Statesman
Posts: 1,208
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Post by Gary L on Aug 8, 2021 0:40:28 GMT
Good to see you back at work on something I can understand. More like fine jewelery than engineering. It is true they are very small, but they are quite prominent and distinctive, so well done Roger! A real achievement in 5" gauge! On Paddington I had to make do with pipes that were overscale (1/16"), which isn't a big issue visually (well, I don't think so) but it made it very hard to make the bends to the necessary intricate shapes. The oil flows fine though; maybe too well. I have played with using wicks ('trimmings') for a slower feed (in Bridget), but without seeing much improvement. The real stumbling block is that you need to know in advance how you are going to arrange the trimmings, and that is the one thing you can't know without a lot of experimentation. Gary
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Post by Roger on Aug 8, 2021 7:16:05 GMT
Good to see you back at work on something I can understand. More like fine jewelery than engineering. It is true they are very small, but they are quite prominent and distinctive, so well done Roger! A real achievement in 5" gauge! On Paddington I had to make do with pipes that were overscale (1/16"), which isn't a big issue visually (well, I don't think so) but it made it very hard to make the bends to the necessary intricate shapes. The oil flows fine though; maybe too well. I have played with using wicks ('trimmings') for a slower feed (in Bridget), but without seeing much improvement. The real stumbling block is that you need to know in advance how you are going to arrange the trimmings, and that is the one thing you can't know without a lot of experimentation. Gary Hi Gary, Thanks for that, I think the pipes will be over scale. I'll try it with the 680 oil, and if that's too thin, I'll use something thicker. I can't see it being a huge problem, I'd rather avoid wicks if I can.
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Post by Roger on Aug 8, 2021 16:16:08 GMT
I'd forgotten that there are another two oilers which are the same as the ones on the Crosshead. These ones are mounted such that one outlet goes inside the Gear Frame while the other goes on the outside. These appear to feed the main pivots for the expansion link. Since these are pretty visible, I ought to fit those too. These are welded onto the Gear Frame, but I'll bolt them on since the Gear Frame is already painted. DSCN5692 by Georgia Montgomery, on Flickr This is where all of these Lubricator boxes fit. Gear frame oiler rear by Georgia Montgomery, on Flickr The bracket has an angled edge to let it overhang the gear frame which will allow the pipes to go one either side. This doesn't look exactly like it is on 1501, I think the box is slightly further inboard on that. However, there's no way to do that with the over scale pipes I'll be using. These may as well be functional, the pivot gets a hard time. Gear frame oiler by Georgia Montgomery, on Flickr
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Post by Roger on Aug 9, 2021 20:58:22 GMT
I've made the six Oilbox bodies, so now it's time to make the lids. The first attempt 3D machined the curved top of the hinge lug and flat top, leaving a ring of scrap. 20210809_115329 by Georgia Montgomery, on Flickr I sawed off the scrap and machined the back of the hinge... 20210809_122910 by Georgia Montgomery, on Flickr ... then drilled the 0.6mm hole which broke because I was a bit clumsy with it. 20210809_123640 by Georgia Montgomery, on Flickr I parted off, adjusting the thickness of the cover. 20210809_124300 by Georgia Montgomery, on Flickr I found that I'd forgotten to finish cut the gap for the hinge, so that was 0.6mm too narrow. Here I'm correcting that on each one. 20210809_142000 by Georgia Montgomery, on Flickr The program was modified to remove the scrap, and the 0.6mm hole was peck drilled using the machine's canned cycle to make sure I didn't break the drill. 20210809_161348 by Georgia Montgomery, on Flickr That all worked a treat, so that the first one fitted nicely. 20210809_172412 by Georgia Montgomery, on Flickr 20210809_172426 by Georgia Montgomery, on Flickr It still needs a little bit of finishing, and of course a hinge rod. Then the M2.5 output pipes need to be made.
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Post by Roger on Aug 10, 2021 20:24:57 GMT
Ok, that was a bit tedious, but six boxes and lids are now finished. They came out really well, accurate enough so that the lids are actually interchangeable. That was a surprise. I now need to sort out the unions and nuts for the outlets. 20210810_211439 by Georgia Montgomery, on Flickr
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Post by keith1500 on Aug 10, 2021 20:49:46 GMT
Not engineering in miniature. Engineering in micro!
Inspiring stuff Roger.
Keith
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Post by chris vine on Aug 10, 2021 20:57:19 GMT
Roger,
Why are you surprised that they are interchangeable? None of us are!!
Chris.
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Post by Roger on Aug 10, 2021 21:14:00 GMT
Roger, Why are you surprised that they are interchangeable? None of us are!! Chris. Hi Chris, Well, the setup is absolutely critical when you're machining something relative to the centre of rotation of a rotary table or 4th axis. You have to be very fussy about how you clock it all up, because any errors are doubled when you turn it over and machine from both sides. Also, that 0.6mm diameter hole is drilled from opposite sides on the body, and it's over 4mm deep on the lid. Getting that all straight is a tall order. I suppose half the battle is realising this, usually from not paying enough attention to these details in the past and finding out the hard way!
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Post by Roger on Aug 12, 2021 12:02:51 GMT
I now need to make at least 16 nuts for the Lubricator Boxes, twelve for these and the rest for the other types that are fitted elsewhere. The undercut at the base of the thread is to make sure the fitting will screw up as far as it needs. It also gives the swaged end of the pipe somewhere to go if I form it over a little more on the inside. There's not much room in there, so every little helps. You can see that I've created a milling tool path for this, assuming it will be done with a T-slot type of cutter rather than a micro boring bar on the Lathe. I can do this in a much more controlled and consistent way on the Mill. Nut undercut by Georgia Montgomery, on Flickr This is the setup, using the 4th axis as a convenient way to hold and set up the ER32 collet. 20210812_094756 by Georgia Montgomery, on Flickr I'm using 1/4" Colphos for these, turned down to 4mm to give the milling cutter less to do. That's a 1.5mm diameter 3-flute. I've chosen that size of cutter so that I can machine all of it in one operation, including the 1.7mm diameter through hole for the pipe as well as the outside 3mm AF hex. 20210812_094809 by Georgia Montgomery, on Flickr I decided to use a 2-flute Carbide PCB cutter that's 2mm diameter for the T cutter. Here I'm setting the inside of the wheel to be level with the end of the cutter on a green grit grinding wheel on the Jones & Shipman Tool and cutter grinder. 20210812_111532 by Georgia Montgomery, on Flickr I fitter this with a rudimentary DRO, using Mitutoyo 1um resolution plunger clocks. Yes, you can get really accurate ones if you look on eBay and they don't cost the Earth. 20210812_112045 by Georgia Montgomery, on Flickr I set this up to give a 0.7mm section at the end, and ground it 0.4mm deep to give plenty of clearance. I'm only undercutting by 0.3mm 20210812_114222 by Georgia Montgomery, on Flickr Here's a wobbly video of the last couple of cuts as it finishes. I had to be careful to make sure the plunge and finish were on the centre line, there's not much room since the tapping size is 2.05mm, and the cuttere is 2mm! 20210812_120142 by Georgia Montgomery, on Flickr And here's the first one, tapped M2.5, chamfered with a needle file and parted off. I'd better make more than I need, I'm sure to lose at least one! 20210812_124217 by Georgia Montgomery, on Flickr And here are the rest of the batch, enough for all of the oilers and a spare. 20210812_225119 by Georgia Montgomery, on Flickr
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Post by Roger on Aug 15, 2021 21:52:03 GMT
The Oil boxes are attached to the Gear Frames with brackets that are welded onto the inside of the rear angle. I've already painted that part, else I'd probably have riveted it on. I don't have any pictures that show the extent of the bracket, but since you can't really see it, it's not important. I've opted to bolt it onto the angle with M1.4 bolts that are close to the back of the Gear Frame so they won't be easily visible. I'll probably try to patch up the paint where the bolt ends up flush on the side where it can be seen. I'm not aware of seeing this detail on any locomotive other than that amazing Glass Case model that came up for sale on Station Road Steam some time ago. I don't think it's on Paddington, but I might be mistaken. Anyway, it's not a perfect reproduction, but it's close enough. DSCN5692 by Georgia Montgomery, on Flickr The bracket for the Valve Crosshead looks like this. 20180110_134225 by Georgia Montgomery, on Flickr These are made from 0.6mm thick Mild Steel. I'm using the High Speed Spindle for this, just to save running the main spindle very fast. 20210815_212441 by Georgia Montgomery, on Flickr The holes were drilled with PCB Carbide ones of course, and the profiles were cut with a 2mm Carbide 2-flute. I've defined the tool path to be the exact depth of the material, but I've included four shallow sloping nibs that are 0.3mm high to keep them in place. The roughing cut leaves 0.2mm, cutting in two passes, and the finishing cut cleans that up in one pass. I do it this way to make sure the nibs don't get torn. Slowly and gently saves having to start again when it breaks loose. 20210815_212448 by Georgia Montgomery, on Flickr These cleaned up nicely with needle files, I just need to bend the ones for the Crosshead lubricators. 20210815_222537 by Georgia Montgomery, on Flickr
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Post by Roger on Aug 21, 2021 22:25:16 GMT
I decided to make the outlets for the pipe unions from Phosphor Bronze so that there's no danger of stripping the threads or them shearing off when I tighten the nuts. The arrangement below is me hedging my bets on what's going to work with regard to feeding the oil. I'm using 680 grade oil, so I think this ought to work ok with the 0.6mm diameter outlet hole and 0.7mm tube bore. If that's not enough delivery, I'll switch to a slightly lighter oil. If it's too much, I'll insert a piece of copper pipe into the clearance hole and use a wick. One way or another, I'm sure it can be made to work. Sectioned oil box assembly by Georgia Montgomery, on Flickr However, this does present some Engineering challenges, because I need a clean thread at both ends and I need to also drill it from both ends. I could potentially drill both the holes from the back, but it's fiddly setting it up where there's no surface to set it to. I could use a feeler gauge, but I thought I'd just turn it round. The first one was threaded and then the chamfer added before drilling on the mill. In the end, I've opted for drilling the hole first, then chamfering and finally threading. I'm doing this on the mill for three reasons. Firstly I have a high speed spindle more suited to small diameters. Secondly, there's no issue with runout like there is on a Lathe, where the drill might be slightly off the centre of the work. Thirdly, I can control the speeds, feeds and pecking operation more precisely than I can drill it by hand, and that will save breaking drills. 20210821_165401 by Georgia Montgomery, on Flickr Here's a trial fitting on a piece of pipe I flanged earlier. 20210821_170708 by Georgia Montgomery, on Flickr The back is recessed on the Mill, using the M2.4 fixture and a locking screw in the back. I've also added a nut on the front on the second one, which helps hold if more securely. 20210821_180237 by Georgia Montgomery, on Flickr Anyway, that's one pair done. I need to Silver Solder those in to see how that needs to be done. I'll protect the threads, but doubtless one or more will need cleaning up. I'm anticipating having to make a tiny hardened nut runner to do that... we'll see. 20210821_230723 by Georgia Montgomery, on Flickr
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Post by terrier060 on Aug 22, 2021 13:56:16 GMT
Bill used wick feeds with worstedtrimmings in his Speedy which worked well. The wicks were held on very fine wire.
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Post by Roger on Aug 22, 2021 20:59:08 GMT
Bill used wick feeds with worstedtrimmings in his Speedy which worked well. The wicks were held on very fine wire. Hi Ed, I think he was probably using much thinner oil than I'm proposing. I'm not sure if this will work with wicks at all. It will need a bit of experimentation to see what works best. Ideally I'd like to stick with the 680 grade if possible so it stays in the bearings longer.
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Post by Roger on Aug 22, 2021 21:06:34 GMT
I've spent much of the day machining the M2.5 outlets for all of the Oil Boxes. It's fiddly and time consuming, but it's finally done. Here are all of the parts required for them, I'll probably Silver Solder them next. 20210822_215454 by Georgia Montgomery, on Flickr I printed out four spray mounts for the brackets yesterday while I was printing the cable tidy. I've got a standard model for the M8 thread and a flange, so all I need to do is to change the shape of the flange and add the fixing holes. It only took a couple of minutes. They're a bit stringy, so I'll pull most of that off and run the hot air gun over them to tidy them up. 20210822_220215 by Georgia Montgomery, on Flickr
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Gary L
Elder Statesman
Posts: 1,208
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Post by Gary L on Aug 23, 2021 18:46:10 GMT
Bill used wick feeds with worstedtrimmings in his Speedy which worked well. The wicks were held on very fine wire. Hi Ed, I think he was probably using much thinner oil than I'm proposing. I'm not sure if this will work with wicks at all. It will need a bit of experimentation to see what works best. Ideally I'd like to stick with the 680 grade if possible so it stays in the bearings longer. Yes indeed. Different grades of oil for different oilers? That way madness lies! I think your 680 grade will be fine, especially as the loco warms up. Oil seems happy to run anywhere it can find a hole, the only difference is how fast. On my Bridget the oil cups empty quite fast; too fast really, but I don’t mind, because on these small components thick oil stays around a long time. I expect I use too much, but unlike in full size, I don’t earn a bonus for saving oil! Gary
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Post by Roger on Aug 23, 2021 20:22:34 GMT
Hi Ed, I think he was probably using much thinner oil than I'm proposing. I'm not sure if this will work with wicks at all. It will need a bit of experimentation to see what works best. Ideally I'd like to stick with the 680 grade if possible so it stays in the bearings longer. Yes indeed. Different grades of oil for different oilers? That way madness lies! I think your 680 grade will be fine, especially as the loco warms up. Oil seems happy to run anywhere it can find a hole, the only difference is how fast. On my Bridget the oil cups empty quite fast; too fast really, but I don’t mind, because on these small components thick oil stays around a long time. I expect I use too much, but unlike in full size, I don’t earn a bonus for saving oil! Gary I suspect I'll find the same over oiling, and I agree that too much is much better than too little. It ought to be easty enough to put a wire in the hole to restrict the flow, assuming that does actually help of course.
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Post by Roger on Aug 23, 2021 22:08:00 GMT
The Phosphor Bronze threaded outlets need to be Silver Soldered to make them strong and oil tight, so that's being prepared here. I used Tippex on the threads, being careful not to get it up against the bottom of the box. I don't want it wicking into the thread, preventing it from Soldering. 20210823_113147 by Georgia Montgomery, on Flickr The inside has a 6mm long piece of 1mm diameter Silver Solder dropped into the pocket, and flux added. I've also carefully dropped a blob of Tippex into the hole, in case some Silver Solder goes astray. Heating this up obviously moves the Silver Solder around, I used a piece of Titanium Welding rod ground to a point to poke it into the right place when the flux went clear. 20210823_111602 by Georgia Montgomery, on Flickr All six done. I should have smothered it in flux like I usually do, but I forgot to do that. Now I've got a lot more cleaning up to do. 20210823_113935 by Georgia Montgomery, on Flickr I first used the Ultrasonic Tank, and then some Sodium Hydroxide solution in a jar in the Ultrasonic Tank. That got some of it off and softened the rest to the point where I could get it off with needle files and emery paper. 20210823_122903 by Georgia Montgomery, on Flickr Anyway, here's the first one. You can see that the Silver Solder stayed inside the threads. There was only just enough to go around them all, I didn't want it running everywhere. 20210823_222044 by Georgia Montgomery, on Flickr
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