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Post by ettingtonliam on Dec 9, 2020 0:31:13 GMT
They have also removed the vacuum brake gear (or at least the external piping) and steam heat. Not needed at the NCB! Malcolm So they have! And even more interesting, there are no visible scars on the buffer beam, so this loco has been specially ‘titivated’ for the new buyer! Gary Can't imagine any loco needing to be 'titivated' for the Coal Board. All they wanted was something that would steam and go.
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Post by Roger on Dec 9, 2020 23:10:15 GMT
Time to have a go at making the Injector Cones. This is the three in one Cone comprising the Condensing, Combining and Delivery Cones separated by radially drilled holes with diameters that give the required gaps. Here I'm using a 1mm PCB drill as a Centre Drill... 20201209_114415 by Roger Froud, on Flickr ... followed by a #74 Slow Helix drill for Brass. This is actually SAE660 Leaded Bronze though, but it machines pretty much the same. The O-ring grooves are dimensioned to only give 10% nip, so it's easier to insert them without snagging. More on that later. I need this hole to go right the way through, and that's a full 16mm. I did this 0.5mm at a time, fully withdrawing the drill on each bite. This was done with my chunky tailstock, there's no need to feel what's going on, you just have to watch the DRO and move gently. 20201209_120040 by Roger Froud, on Flickr Then it was on to the 4th Axis for drilling the holes. This needs to run dead true to the centre of rotation and the drill to be set up spot on so it intersects the middle exactly. 20201209_121501 by Roger Froud, on Flickr The Eagle eyed amongst you will notice that this has suddenly got shorter... because I referenced the holes from the wrong end on the first one and scrapped it. Doh! Here's a wobbly video of me doing just that. 20201209_123137 by Roger Froud, on Flickr This is the 0.85mm holes on 45 degree angles which creates the gap in the Mixing Cone section... 20201209_143001 by Roger Froud, on Flickr ... and this are the 1.1mm holes for the gap between the Mixing and Delivery Cones. 20201209_152849 by Roger Froud, on Flickr This is the way I'm setting the reference length for the DRO on the Condensing Cone end. 20201209_185453 by Roger Froud, on Flickr 20201209_185955 by Roger Froud, on Flickr 20201209_190005 by Roger Froud, on Flickr That was parted off and then trimmed to length and then reamed with the 7 degree reamer. 20201209_215506 by Roger Froud, on Flickr The Steam Cone is very simple, and the 9 degree reamer was again set up using the 25mm Slip Gauge. This works really well, you can feel it gently get nipped by the tailstock movement and it's easy to set the DRO to zero at that point. 20201209_153629 by Roger Froud, on Flickr 20201209_153945 by Roger Froud, on Flickr That was then parted off and left 0.3mm over size because I want to make sure this nips up against the retaining cap. I'll set the exact length when it's been tested. This is the 2.8mm drill being used to open out the back leading to the throat. There's no need for a fancy blended radius. 20201209_155410 by Roger Froud, on Flickr So far so good. In my opinion this is much easier to make than the traditional separate cones because the alignment between the cones is contained within the one unit and it doesn't need a press fit in the body. I think there's going to be an issue inserting these without damaging the O-rings, so I've designed a chamfering tool to add a lead in where the threads end on the body. I'll make that shortly and also the spacer. 20201209_215800 by Roger Froud, on Flickr
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dscott
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Post by dscott on Dec 10, 2020 0:38:55 GMT
Superb Roger. And they were done. None of this tiny bits that are an interference fit in a reamed hole way beyond looking down after pushing both of them in!!! Then the gap is wrong!!!
David and Lily.
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Post by Roger on Dec 10, 2020 8:12:11 GMT
Superb Roger. And they were done. None of this tiny bits that are an interference fit in a reamed hole way beyond looking down after pushing both of them in!!! Then the gap is wrong!!! David and Lily. Hi David, My thoughts exactly. The simpler it is to get the cone geometry right, the better. However, we don't know if this will work yet, so it's too early to celebrate. Watch this space!
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Post by 92220 on Dec 10, 2020 8:58:44 GMT
Brilliant job Roger!!! If that works, making all the cones as one will be a 'game changer' for injector making!!
Bob.
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Post by Roger on Dec 10, 2020 9:04:21 GMT
Brilliant job Roger!!! If that works, making all the cones as one will be a 'game changer' for injector making!! Bob. Thanks Bob, cross all your fingers and toes that it works!
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oldnorton
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Post by oldnorton on Dec 10, 2020 10:47:39 GMT
if [when ![:)](//storage.proboards.com/forum/images/smiley/smiley.png) ] this injector works on test it will be a remarkable, innovative outcome. It should be called the Froud Injector and will be worthy of a proper write up and publication. Norm
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Post by delaplume on Dec 10, 2020 12:30:26 GMT
if [when :) ] this injector works on test it will be a remarkable, innovative outcome. It should be called the Froud Injector and will be worthy of a proper write up and publication. Norm and hopefully someone will take up production as well ??..........
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Post by runner42 on Dec 10, 2020 22:08:12 GMT
Brilliant job Roger!!! If that works, making all the cones as one will be a 'game changer' for injector making!! Bob. Could this be a candidate for 3D printing? Brian
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Post by Roger on Dec 10, 2020 22:12:26 GMT
Brilliant job Roger!!! If that works, making all the cones as one will be a 'game changer' for injector making!! Bob. Could this be a candidate for 3D printing? Brian Hi Brian, I don't think you could 3D print an injector unless it was enormous. The surface finish you need in the cones is way beyond what you print. You could possibly 3D print the body though, but the problem is that the materials you can use are really difficult to machine, and that's not good. I think a lost wax casting is the way to go for the body. You could CNC machine the cones in quantity for a reasonable price, but in small numbers it's going to be expensive.
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Post by delaplume on Dec 10, 2020 22:21:43 GMT
Just as an aside}---- try using Black, felt tip marker pen on a light coloured 3D printed plastic and see what happens......most odd !!
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Post by Roger on Dec 10, 2020 22:33:20 GMT
This is the spacer for the Steam Cone that sets the Regulation Gap. However, it does have to allow the water from the inlet to get through, and that's what the gap is for. This is made from Phosphor Bronze because it's very thin and it needs to be strong. 20201210_145615 by Roger Froud, on Flickr I've left the small bridging piece to give it a little more strength. I've left it slightly long because I can shorten it if the Regulation Gap is too large. 20201210_153810 by Roger Froud, on Flickr I tried to bend the old Pressure Gauge pipe into a bit more of a 'U' shape, but that was too stiff and sheared off the end. So here's a new one that gives a slight 'U' that will fill with water. 20201210_220428 by Roger Froud, on Flickr 20201210_221645 by Roger Froud, on Flickr The Silicone wire arrived today, so I've finished wiring it all up. However, it's too late to fire this up tonight, but I'll give it a go tomorrow. 20201210_222044 by Roger Froud, on Flickr
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Post by David on Dec 10, 2020 23:01:35 GMT
Love the injector cones.
It's getting quite exciting now. Where did you get that fancy number drill from? I've never heard of one esp for brass. I was talking to a friend this morning who said number drills were used for carb jets, so perhaps they were made for that?
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Post by Roger on Dec 10, 2020 23:39:05 GMT
Love the injector cones. It's getting quite exciting now. Where did you get that fancy number drill from? I've never heard of one esp for brass. I was talking to a friend this morning who said number drills were used for carb jets, so perhaps they were made for that? Hi David, I use Drill Service in Horley who stock just about everything under the Sun when it comes to drills, reamers and taps. I don't know what the history of Number or Letter drills was, but they were a widespread standard both in the UK and US. You see them mentioned a lot by LBSC, and I suppose there's a better choice of drill sizes at small increments compared to fractional sizes. Now you can get Metric drills in increments down to 0.05mm there isn't a problem. I think it pre-dates the internal combustion engine. It's an obsolete system now, but in this case it came in handy because a number drill happened to be available just under the size I needed for the One Piece Cone. You can buy slow helix drills in any size, they're used commercially where the material is brittle such as with Brass, Bronze or Cast Iron. The slow helix is the equivalent of having less top rake on a Lathe tool. It encourages the material to shear rather than dig in. For larger sizes you can manually add a flat to achieve the same thing, but not on something this small. I just thought it would make drilling the Bronze easier since the hole is so deep.
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Post by coniston on Dec 11, 2020 8:37:34 GMT
Thanks for the link Roger, not heard of them before and a quick scan of their range is most impressive, will definitely use them for special drills etc. Look forward to seeing the injector progress.
Chris D
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Post by 92220 on Dec 11, 2020 8:56:11 GMT
Number drills were an early equivalent of metric sizes, under the British Standards system. They lost favour, when engineering in the UK, changed over to the Metric measuring system. They are still available, and if you have a set, very handy when one of your metric drills goes walkabout!!
Bob.
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Post by Roger on Dec 11, 2020 10:03:57 GMT
Thanks for the link Roger, not heard of them before and a quick scan of their range is most impressive, will definitely use them for special drills etc. Look forward to seeing the injector progress. Chris D Hi Chris, They also source special taps and dies, I've had some oddball ones made in the past for our Spindle Repair business. They're not the cheapest, but they only supply industrial quality products. They're usually pretty quick to ship, or source the items if they're out of stock. I've just ordered some M7 x 0.5 (fine) taps from them which are not a preferred Metric Fine size, but are going to make the end caps of the injectors easier to make and will provide more clearance for the O-rings and allow a larger chamfer on the bore.
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Post by delaplume on Dec 11, 2020 10:47:46 GMT
Thanks for the link Roger, not heard of them before and a quick scan of their range is most impressive, will definitely use them for special drills etc. Look forward to seeing the injector progress. Chris D Make that 2 !!.......have just added their link to my desktop array........... So there IS life after Tracy tools then ??---LoL !! Thanks Roger..
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Post by Roger on Dec 11, 2020 11:54:15 GMT
That's a bit blurred, but it's showing 90PSI. I've just set the Safety Valves which pop nicely and seat quickly, so that's good news. No weeps on the fittings too so that's also pleasing. However, it's not controlling to a temperature as far as I can see, so I need to fire the controller up on the bench and investigate what's going on. I can run a lamp load and maybe even use that to feed back heat into the thermistor. I suppose it's also possible that the feedback is just not quick enough. Anyway, so far so good, at a pinch I could use it like this but I'd rather get it right. If I can't make the feedback behave, I'll just make the output of the element follow the position of the potentiometer. 20201211_105000 by Roger Froud, on Flickr At least I can see the pressure climbing quickly as soon as the power is applied.
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Post by JonL on Dec 11, 2020 14:30:37 GMT
Is the element switched on and off to control the temperature or voltage controlled (via PWM or similar)? By the first option I mean like a conventional immersion heater.
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