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Post by Roger on Jan 27, 2022 11:51:59 GMT
Superb Roger a carefully thought out way of doing things. A long list of your hints and tips growing by the day. Just think of the curved steam pipe covers for the Locomotive at the front of the train done the same way. Just imagine being at Paddington for this. CNC solves just so many problems. David and Lily. Thanks David. CNC certainly makes life a lot easier, but you could still use this same method without. It would just take a lot longer. I'm just showing how I choose to do things, not suggesting that anyone should do the same. My tool set lends itself to sculpting metal, rather than having to make things using circles and straight lines that you're limited to with manual machines. It opens up a whole new set of solutions that aren't really viable using traditional methods.
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Post by Roger on Jan 27, 2022 20:32:23 GMT
Unfortunately, I didn't stop the parting off soon enough, and the part fell down and clouted the chuck jaw. It looks like it actually got between the Cross Slide and the Jaw because there's a ding in both ends. Anyway, you can see the mark on the left where the join is, so that needs addressing. I hate using filler because it doesn't really stick that well, and any polishing is going to wear that away rather than the surrounding metal. 20220127_111534 by Timothy Froud, on Flickr It looks worse from the inside. 20220127_111554 by Timothy Froud, on Flickr I decided to add a blob of Silver Solder so that I can fill it in a more robust way. Here I've used a scrap of Boiler Insulation to grip it in the vice. I've smothered it in flux after painting around the area with Tippex so the Silver Solder doesn't run everywhere and the dreaded Black Curse is kept to a minimum. You can just see that I've also made a little loop of Silver Solder wire which will obviously melt before the metal gets Red hot. However, I thought it was a good idea to get some Silver Solder on the job to help draw any extra in. I've got some chunky Silver Solder rod, so I ground that to a point to add more when it was hot enough. 20220127_113500 by Timothy Froud, on Flickr That seemed to turn out ok 20220127_114349 by Timothy Froud, on Flickr This is how that looked after 30 minutes in the Ultrasonic Tank. 20220127_135658 by Timothy Froud, on Flickr 20220127_135715 by Timothy Froud, on Flickr That cleaned up nicely with needle files. 20220127_142636 by Timothy Froud, on Flickr 20220127_142817 by Timothy Froud, on Flickr So here are all the various handed components, all of them are different! It's handy to have the 3D model on the screen next to it when you're machining so you can check the orientation and where the various holes and chamfers are. 20220127_171809 by Timothy Froud, on Flickr Here's that one with the notch filled in, it doesn't show any more. 20220127_172011 by Timothy Froud, on Flickr 20220127_172208 by Timothy Froud, on Flickr The Snifting Valve flange will be Silver Soldered to the top part, providing a convenient handle to get hold of it. I've increased the size of the chamfers on the magnet pockets so that it's easier to line up. It drops in with a reassuring snap and stays together really well. Up next are the Collar pieces. I think I can machine the bottom part as one piece, cutting it in half with a Vee notch in the back since it's pretty thin there. We'll see.
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Post by Roger on Jan 28, 2022 23:20:42 GMT
This is one of the collars at the top of the Steam Pipe Cladding. It's a really tricky 3D shape, with a thin flange that fits against the Smokebox and also has a stepped and angled hole for the main tube Here I've roughed out the basic shape with a 5.5mm cutter and this is the parallel finishing cut to create the fine detail. 20220128_075149 by Timothy Froud, on Flickr The video below shows the Radial machining operation which does cuts that radiate from the middle. Unfortunately, I didn't leave enough material for this to clean up, so this one is scrap. 20220128_075201 by Timothy Froud, on Flickr I decided to press on to prove the other programs and methods before making a second one though. This is a bit tricky to set up. I've used the graduations on the side of the 4th axis to get it to 15 degrees. Then I've used the edge finder on the corner because I can find out from the 3D model how far that is from the centre. The hole details were copied from the 15 degree angled plane, and pasted onto the top of the 3D model as a separate sketch. The CAM package I've got doesn't allow you to align the machine axis to an arbitrary angle,, so I've had to get the sketch parallel to the table. 20220128_205708 by Timothy Froud, on Flickr Being on a slope means that I need to go 11.5mm deep . The 1mm finishing cutter only has 10mm of flute, but i can cheat by breaking the path into two halves. That way I can avoid having to go to the full depth on the side that's already fully cut to the centre line on that half. 20220128_220134 by Timothy Froud, on Flickr
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Post by Roger on Jan 29, 2022 22:45:44 GMT
Just a reminder of what I'm trying to make, here's the collar at the top where the Cosmetic Steam Cover meets the Smokebox. Snifting valve fitted to locomotive by Timothy Froud, on Flickr This time I've left enough material after roughing to get it cleaned up better with the finishing cut. It's still not quite right, but it's near enough to finish by hand. 20220129_170408 by Timothy Froud, on Flickr The main tube is at 15 degrees from the face, and you can see that this has been machined with the step in diameter for the two halves. The top half is slightly larger to make it look like it overlaps the bottom half. The was roughed out to 11.5mm deep with an 8mm cutter first. The 1mm PCB burr only has 10mm of flute, so I split this operation in half. That way the half that's highest can be machined to half the depth, and the other half doesn't need the cutter to go where it would run out of flute. Hopefully that makes sense. 20220129_214812 by Timothy Froud, on Flickr Anyway, that fits nicely without being tight. 20220129_214800 by Timothy Froud, on Flickr The next challenge is to see if the rivets around the flange are worth adding. 0.8mm rivets might be too big, I'll have to see. The only smaller rivets i've got are 0.5mm Brass ones, and they aren't that good. Brass is too soft for this really, they are really fiddly to fit without them getting mangled. After that, I've decided to slit this with the very fine slitting saw, rather than make six separate pieces.
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Post by 92220 on Jan 29, 2022 23:11:27 GMT
Hi Roger.
A super bit of work there. Very clever!! If the rivets are dummy, why can't you just drill holes for them and fit using Loctite Retaining?
Bob.
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Post by Roger on Jan 29, 2022 23:33:18 GMT
Hi Roger. A super bit of work there. Very clever!! If the rivets are dummy, why can't you just drill holes for them and fit using Loctite Retaining? Bob. Thanks Bob, Maybe that would work, it's a very thin flange though, and not much for them to adhere to. I'll have a closer look at this tomorrow when I have to make a decision.
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Post by Roger on Jan 30, 2022 21:37:35 GMT
The clearance over the bottom of the Smokebox Saddle is at yet another angle, so that's getting tidied up here. 20220130_111521 by Timothy Froud, on Flickr The smallest Slitting Saw I have is one with a 1/4" hole, so I had to make an arbor for that since I didn't have one. It's only 0.5mm thick, so it won't really show that the parts don't completely meet. With a coat of paint, that gap will be even smaller. The cut isn't across the centre line, it's 1.5mm below. I've gone 5mm deep with the cut in 0.5mm increments to make sure the cutter doesn't wander. That happens if you try to do it all in one pass. This is one of those rare cases where I commanded the machine with single line typed inputs rather than use a program. 20220130_163413 by Timothy Froud, on Flickr The first cut was right across, but this other one at the bottom just cuts the lower section in half. 20220130_170135 by Timothy Froud, on Flickr 20220130_171200 by Timothy Froud, on Flickr It furns out by good fortune, not design, that the whole thing stays together as one piece once parted off. That should help no end when trying to get this in the right place You can see the place where the two different radii meet bu the angled cut has left a wedge shaped piece that needs removing... 20220130_204422 by Timothy Froud, on Flickr ... something like this. 20220130_205813 by Timothy Froud, on Flickr I've tidied up most of the machining marks on the collar, and this is the first proper trial assembly to see if it's close. 20220130_210228 by Timothy Froud, on Flickr The real challenge is going to be getting this firmly attached in the right place and with the curve that exactly butts up against the outside of the Smokebox. 20220130_210239 by Timothy Froud, on Flickr
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Post by Roger on Feb 3, 2022 21:06:04 GMT
The Silicone Rubber bungs arrived early from China, so I made a punch from 8mm Silver Steel to put the hole through to top for the Steam Pipe. I did the first one this way... 20220203_203653 by Timothy Froud, on Flickr ... but decided that it wasn't as close to the middle as I'd have liked. So this is a little pocket arrangement to hold the head truly central and a shortened punch to reduce the error there too. 20220203_204810 by Timothy Froud, on Flickr Yes, I know it's probably over the top, but it took 5 minutes. This is likely to be a consumable item, so being able to quickly knock out a batch might be handy. 20220203_205303 by Timothy Froud, on Flickr These were slit with a fresh Scalpel, and they fit a treat. Remember, this is just a dust cover to keep the worst of the Ash out of the Spherical Metal seal. So I'm really pleased with this solution, and it's all thanks to Kerrin's brainwave! Thanks for that! 20220203_205652 by Timothy Froud, on Flickr
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Post by Roger on Feb 4, 2022 22:51:24 GMT
This is going to be a pair of tapered spacers that hold the flange in place while it's being tack welded . 20220204_094344 by Timothy Froud, on Flickr I've added a small flat so I know exactly where to part it off. It's not easy to measure the exact distance from a corner. 20220204_101910 by Timothy Froud, on Flickr The tube was then slit in two to make a pair of clam shells... 20220204_105500 by Timothy Froud, on Flickr ... which look like this after parting off and tidying up with a file. 20220204_110858 by Timothy Froud, on Flickr This is a wobbly video of the Snifting Valve flange being roughed out at the full depth in one operation, using 0.1mm cuts. 20220204_212940 by Timothy Froud, on Flickr The flange has two M1.6 tapped holes to attach the Snifting Valve. 20220204_215801 by Timothy Froud, on Flickr A quick sanity check to see if it fits. 20220204_215740 by Timothy Froud, on Flickr That was parted off and faced off to look like this. I bought a few lengths of 10mm Silver Steel, one being handy for keeping this all together and concentric to the middle. There's a 0.5mm shim between the bottom halves which is being pinched by the magnets. The assemblies still fit inside the collars, so we're fast approaching the point where they are going to be tacked on. I just need to do a few more checks and try the clam shell registration pieces. 20220204_221811 by Timothy Froud, on Flickr
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Post by Roger on Feb 5, 2022 20:44:15 GMT
The two clam shell tapered spacers are held on with Florist's wire and the blob of Blu Tack just stops it from spining round while the first tack weld is done. 20220205_181550 by Timothy Froud, on Flickr The 10mm Silver Steel is bearing on the reamed holes on the separate segments, and there are 0.5mm shims in the bottom where there's a gap for the paint. The two parallel clam shells are different diameters to suit the different radii of the two halves. 20220205_181608 by Timothy Froud, on Flickr This is how it looks when tacked with the TIG welder... 20220205_183835 by Timothy Froud, on Flickr ... which is much prettier than the back! 20220205_183849 by Timothy Froud, on Flickr You can see that there's still a sliver of Steel holding this all together, and those were cut away with a Junior hackaw to separate the segments... 20220205_183904 by Timothy Froud, on Flickr ... like this. 20220205_184858 by Timothy Froud, on Flickr The area immediately next to the joint was protected with Tippex and piece of Silver Solder was formed to fit into the corner. That's held on by being wrapped around the back. 20220205_185907 by Timothy Froud, on Flickr The whole thing was then smothered with flux and heated to form the joints. 20220205_191851 by Timothy Froud, on Flickr 20220205_191859 by Timothy Froud, on Flickr 20220205_192734 by Timothy Froud, on Flickr This is the second one getting ready for the same process. 20220205_194439 by Timothy Froud, on Flickr There isn't really enough Silver Solder to completely fill the joint and make a fillet, and that's exactly what I want because this collar is supposed to be a separate piece. 20220205_200212 by Timothy Froud, on Flickr
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Post by keith1500 on Feb 6, 2022 9:24:02 GMT
May be finish the fillet off with soft solder…. Edit May be finish the fillet off with soft solder…. I don't think it needs a fillet to be honest, there isn't one one the full sized locomotive. Sorry miss read what you said. You don’t want a fillet.
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Post by Roger on Feb 6, 2022 11:35:50 GMT
May be finish the fillet off with soft solder…. I don't think it needs a fillet to be honest, there isn't one one the full sized locomotive.
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Post by Roger on Feb 6, 2022 23:36:19 GMT
I thought I might just rely on strong tack welds to hold the Snifting Valve Flanges in place. However, I nipped the first one in the vice, and that ended up not being square. So I had to grind away and break one of the tacks so that it could be bent back true. This is a much better setup that holds the parts square... 20220206_223619 by Timothy Froud, on Flickr ... however I couldn't get in there with the torch so moved it around a bit like this... 20220206_224028 by Timothy Froud, on Flickr ... and then I didn't quite bridge the joint. 20220206_224318 by Timothy Froud, on Flickr So that was set up again, and this time it's definitely got it. 20220206_225455 by Timothy Froud, on Flickr Everything looks to be true now, so I've bent up some Silver Solder and added Tippex to the area around the joint in preparation for Silver Soldering them in place. 20220206_232014 by Timothy Froud, on Flickr
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Post by Roger on Feb 7, 2022 22:18:22 GMT
It's messy, but it's not black, so this is easy to clean up. 20220207_161922 by Timothy Froud, on Flickr 20220207_200818 by Timothy Froud, on Flickr The bottom mating part for the Snifting Valve flange prevented the two halves from coming together when the magnets were in place. That's because the angle on the flange is just off the vertical. That was fixed by filing the opening so that it's now square. Fortunately, it doesn't really show that much. 20220207_214420 by Timothy Froud, on Flickr 20220207_214500 by Timothy Froud, on Flickr This is almost ready for machining the curve where it mates with the Smokebox. i'm not sure how I'm going to to that yet, but i'd made some clam shells to hold the outside in the 4-Jaw on the 4th axis.
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Post by Roger on Feb 10, 2022 22:55:38 GMT
Finally it's time to figure out how to machine the curve where the Cosmetic Steam tube cover mates with the Smokebox. This is a bit tricky because there are no readily available things to set up to. However, I've copied the basic 2D geometry to a separate 3D model so I can extract the key dimensions and create a tool path that relates to those. So this is set on the centre line of the assembly, and the reference line at 6.754 is to the edge of the cosmetic collar. Smokebox curve geometry by Timothy Froud, on Flickr I need to machine this in another plane, but it's easier to clock this way. I'm using the exposed ends of the top part to adjust the 4th axis to that it's level. I'm using the two Clam Shells with different radii to hold this together as well as the magnets. 20220210_212941 by Timothy Froud, on Flickr It turns out that the reamed hole is still a precision fit on a piece of 10mm Silver Steel, so that's what I'm using to find the centre. 20220210_213655 by Timothy Froud, on Flickr One of the tapered Clam Shells was used to locate the edge of the cosmetic collar. The Silver Steel is 5mm, so the X-axis was first moved 2.5mm left and zeroed. Then it was moved a further 6.754mm left and zeroed so that the Zero for the CAM program matches where I am on the job... hopefully! 20220210_215126 by Timothy Froud, on Flickr It's too late to start machining this tonight, and I also need to very gingerly discover how much material needs to be removed. I don't want any dramas at this stage! I'll do a 'sanity check' on the final position of the cutter to see if that's plausible, and I'll probably aim to be at least 1mm away from the final position for roughing. It does feel like a pretty solid setup though, so there shouldn't be any issues as long as I'm careful and take it slowly. This is definitely not a job for beginners.
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Gary L
Elder Statesman
Posts: 1,208
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Post by Gary L on Feb 11, 2022 0:13:26 GMT
Wow!
This is a manufacturing tour de force, with Roger displaying incredible skill! These humble items probably require more geometrical bravura than those memorable injectors!
Lest it is discouraging to the less accomplished engineers amongst us, it is worth saying that there are other ways of doing it. The Paddington drawings for example, indicate a miniature replica of how the covers are made in full-size. Once I had tracked down some brass tube of the right diameter, it was not to difficult to cut it into four half-segments, with longitudinal lap joints and a collar lap joint at mid-height. (Remember you need twice as much length as you think, because you can only get half a circumference each time, as the longitudinal cuts steal so much material). It sounds a bit intricate, and it is, but it doesn’t require Roger-levels of skill. This is 1.5” scale of course, it would be more delicate in Speedy size. I recall my Speedy had just clip-on covers; they were open at the back, but this liberty was barely perceptible.
Gary
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Post by Roger on Feb 11, 2022 7:34:28 GMT
Wow! This is a manufacturing tour de force, with Roger displaying incredible skill! These humble items probably require more geometrical bravura than those memorable injectors! Lest it is discouraging to the less accomplished engineers amongst us, it is worth saying that there are other ways of doing it. The Paddington drawings for example, indicate a miniature replica of how the covers are made in full-size. Once I had tracked down some brass tube of the right diameter, it was not to difficult to cut it into four half-segments, with longitudinal lap joints and a collar lap joint at mid-height. (Remember you need twice as much length as you think, because you can only get half a circumference each time, as the longitudinal cuts steal so much material). It sounds a bit intricate, and it is, but it doesn’t require Roger-levels of skill. This is 1.5” scale of course, it would be more delicate in Speedy size. I recall my Speedy had just clip-on covers; they were open at the back, but this liberty was barely perceptible. Gary Thanks Gary, I certainly wouldn't recommend anyone to copy what I've done, it's a lot of work and pretty fiddly. However, it's the sort of thing I enjoy, and it does result in something that is easily serviced. That was the primary goal. In reality, you could make them as you suggest, leaving a slot in the back to get them off. You definitely need some way of doing that. All good fun!
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Post by Roger on Feb 11, 2022 18:09:57 GMT
Originally I was going to use this 16mm cutter, here being set to the right height... 20220211_083400 by Timothy Froud, on Flickr ... and a first roughing cut move to see how close I could start to the stock. 20220211_084054 by Timothy Froud, on Flickr In the end, I decided to use the 16mm Indexable 2-flute with polished inserts, a 2mm depth of cut and 0.12mm per pass to leave 0.5mm extra on the flange. Here's a wobbly video of that in progress. 20220211_085828 by Timothy Froud, on Flickr 20220211_091520 by Timothy Froud, on Flickr 20220211_091542 by Timothy Froud, on Flickr It took a couple of hours, but it's a fairly gentle way of removing the material. 20220211_103043 by Timothy Froud, on Flickr I have to decide whether to bore out the middle and finish this by hand, or go a bit further. 20220211_144233 by Timothy Froud, on Flickr
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Post by Roger on Feb 12, 2022 18:14:20 GMT
I didn't want to go too far with the machining of the flange in case it didn't mate that well with the Smokebox curve. Instead, I decided to bore out the end, and then finish the curve by hand to suit. Here I'm using the 10mm Silver Steel support so I can clock it centrally. Then it's pushed back clear of the end. 20220212_101156 by Timothy Froud, on Flickr 20220212_105032 by Timothy Froud, on Flickr That was pretty close, so I just tidied it up with files. The flange is a little thick, so I might file that down a little more. We'll see. 20220212_162808 by Timothy Froud, on Flickr You'll notice that I've decided not to add the dummy screws to the flange. They're too small for my liking, and just not worth the effort.
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Post by Roger on Feb 13, 2022 12:37:39 GMT
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