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Post by andyhigham on May 18, 2019 16:46:31 GMT
I was thinking about the safety valve bonnet you printed, tell me if I am talking out of my a**e here. There are metal filled filaments available, are these conductive? If so a negative of the bonnet could be printed, like a mould. The outside coated with a non conductive layer then the mould electroplated to the required thickness. after plating the plastic print could be burnt off or dissolved in a suitable solvent
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stevep
Elder Statesman
Posts: 1,070
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Post by stevep on May 18, 2019 16:59:29 GMT
Are you going to fit working test cocks in the other two positions? No, they are just going to be dummies. I don't really want water on the cab floor if I can avoid it. I think Andy had his tongue firmly planted in his cheek!
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Post by Roger on May 18, 2019 17:21:55 GMT
I was thinking about the safety valve bonnet you printed, tell me if I am talking out of my a**e here. There are metal filled filaments available, are these conductive? If so a negative of the bonnet could be printed, like a mould. The outside coated with a non conductive layer then the mould electroplated to the required thickness. after plating the plastic print could be burnt off or dissolved in a suitable solvent That's an interesting proposition, but you don't actually need anything to be conductive to plate it. In the PCB industry it's used all the time to connect the different copper layers. Electroless plated holes are then thickened by electroplating to the desired thickness. This is all copper of course. I don't know if you could add a brass or bronze layer to it though. It wouldn't be difficult to melt out PLA and dissolve the rest with IPA
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Post by 92220 on May 18, 2019 17:38:38 GMT
Hi Andy.
It's a nice idea but electroplating is so thin it would take many days, possibly weeks, to reach a workable thickness.
Bob.
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Post by Roger on May 18, 2019 18:03:53 GMT
Hi Andy. It's a nice idea but electroplating is so thin it would take many days, possibly weeks, to reach a workable thickness. Bob. I think you would be surprised at how quickly you can lay down copper. All PCBs are made with initially thin copper bonded layers. That's because you want to etch away most of it,leaving just the tracks. The bulk of the copper thickness, including that down the holes, is added by electro plating. Another even thicker plating application is in the armature of a very high speed spindle. The squirrel cage is entirely made by electro plating copper into semi circular grooves machined in a magnetic stainless steel shaft. That plating is over a millimeter thick.
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kipford
Statesman
Building a Don Young 5" Gauge Aspinall Class 27
Posts: 566
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Post by kipford on May 18, 2019 19:11:07 GMT
Model Engineer ran a series about a year ago on the manufacture of an ENV aeroengine. In this series the guy building it made the external water jackets of the cylinders by electo plating copper. The issue with the main bulk of the text about the electroplating is vol 220 no 4581. The picture show the water jackets on some of the cylinders. A stunning piece of modelling. Electroplate by Dave Smith, on Flickr
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Post by andyhigham on May 18, 2019 19:40:13 GMT
I guess I wasn't talking out of my a**e then. If copper can be plated easily to the required thickness, then a thin layer of brass can be plated on top Copper plating is relatively easy and safe to do at home
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nonort
Part of the e-furniture
If all the worlds a Stage someone's nicked the Horses
Posts: 277
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Post by nonort on May 18, 2019 20:37:39 GMT
I've got a scrap part made from PLA immersed in water which has been there for two weeks to far. I'll be seeing if that changes in size or goes soft. So far it seems unaffected so that's promising. [/quote]
PLA is hydroscopic and will take up moisture quite quickly. I double bag my stock reels in zip bags with silica between each bag. If left out in the open for long periods it will spoil prints by blow seam fissures in the walls of thin dimensions. Great to see engineering being used instead of blacksmithing.
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jma1009
Elder Statesman
Posts: 5,901
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Post by jma1009 on May 18, 2019 21:29:20 GMT
Many years ago, Jack Poyner gave us a talk in the IWMES on electro plating. He did a book on the subject in the ME Series. He handed round an Isle of Wight 5"g O2 boiler shell to Don Young's design electro plated over polystyrene (subsequently removed). It was pretty much 3mm thickness in copper and quite heavy. It had been done by him in Plessey Radar's chemists section of which he was in charge.
If unpainted, I think for 'Speedy' Roger ought to attempt a brass safety valve cover out of brass gilding metal which has that rather greenish tinge that the GWR safety valve 'bonnets' had, but a plain brass cover turned and machined out of a lump of good quality brass will do equally well.
I expect, as is Roger's habit, he will post his own CAD drawings first same as with the chimney and cap for all to see beforehand, and to comment on where appropriate.
The method of indicating the water level in the pannier tanks I now understand, and thanks to those who clarified this for me.
Cheers,
Julian
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Post by Roger on May 18, 2019 22:59:48 GMT
I've got a scrap part made from PLA immersed in water which has been there for two weeks to far. I'll be seeing if that changes in size or goes soft. So far it seems unaffected so that's promising. PLA is hydroscopic and will take up moisture quite quickly. I double bag my stock reels in zip bags with silica between each bag. If left out in the open for long periods it will spoil prints by blow seam fissures in the walls of thin dimensions. Great to see engineering being used instead of blacksmithing. I too treat my filaments this way, and it's true that they all take up moisture.... but.... it would appear that they don't seem to absorb much after they've been printed, at least PLA doesn't. I found this article is interesting and backs up the results of my albeit shorter experiment. I'm not sure why this should be so, but perhaps the extruding process changes something, it certainly reduces the surface area compared to that of a filament spool. I'll continue the experiment and see if there are any measurable effects in the longer term. For the moment, I'm not overly concerned. If it lasts for 5 years then I could live with that since it's so easy to make another. Ultimately, it could be machined from Brass or Bronze if necessary.
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Post by Roger on May 18, 2019 23:09:00 GMT
Now that the main indicator is finished, it's time to add the dummy test cocks, the first of which is on the removable plate. I want to attach them to the tank because on 1501 there's a hole in the cab and they clearly go through that. The problem is that the plate is only 1.5mm thick, so that's not really enough to attach it to. In the end I decided to make a little Phosphor Bronze blind bush with an M3 hole in it for the test cock to screw into. That requires an extra hole in the plate and a clearance on the 3D printed part to miss it. 20190518_222949 by Anne Froud, on Flickr The bush was made 0.2mm too long and the edges were riveted over into a shallow countersink.... 20190518_224751 by Anne Froud, on Flickr ... and then Soft Soldered with a tiny scrap of Electrical 60/40 solder. The other one was done with Jim Scott's high temperature Silver based Soft Solder so that didn't melt. 20190518_225540 by Anne Froud, on Flickr I used Tippex to stop it running and Comsol flux. A scalpel was used to encourage the solder to go right around. 20190518_225752 by Anne Froud, on Flickr The same was done on the back, you can see how little solder I'm using. 20190518_230259 by Anne Froud, on Flickr After a little attention with needle files, it looks like this. 20190518_231842 by Anne Froud, on Flickr 20190518_231851 by Anne Froud, on Flickr
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Post by 92220 on May 19, 2019 8:38:29 GMT
Hi Roger.
Sounds like processes have changed just a little since I worked in a plating shop in my apprenticeship!! How long would it take, nowadays, to lay down a thickness of 0.80mm? I would think that would be the minimum for a dome.
Bob.
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Post by Roger on May 19, 2019 9:10:57 GMT
Hi Roger. Sounds like processes have changed just a little since I worked in a plating shop in my apprenticeship!! How long would it take, nowadays, to lay down a thickness of 0.80mm? I would think that would be the minimum for a dome. Bob. Hi Bob, That's a good question. I don't really know, I guess it's all down to the current density you can create. I've got a unit from a PCB shop that will deliver 100 amps at 3 volts. I don't know if you can plate Brass though, I'd have to look into that.
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Post by 92220 on May 19, 2019 10:04:18 GMT
All this talk about electroplating has got me investigating the 'net! I have found some very interesting articles which describe thick copper plating...apparently generally referred to as 'electroforming'. There are a number of sites describing 3D electroforming as a parallel to 3D printing. How handy would that be in model engineering!! The one drawback I found to thick electroplating (electroforming) is that the thicker the coating the more chance that the layer can become porous, though there are ways of preventing this. I also found one site that was able to quote a possible deposit time of 40 seconds per millimetre thickness!! That shows how out of touch I got with plating!!!
Bob.
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timb
Statesman
Posts: 512
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Post by timb on May 19, 2019 13:19:36 GMT
All this talk about electroplating has got me investigating the 'net! I have found some very interesting articles which describe thick copper plating...apparently generally referred to as 'electroforming'. There are a number of sites describing 3D electroforming as a parallel to 3D printing. How handy would that be in model engineering!! The one drawback I found to thick electroplating (electroforming) is that the thicker the coating the more chance that the layer can become porous, though there are ways of preventing this. I also found one site that was able to quote a possible deposit time of 40 seconds per millimetre thickness!! That shows how out of touch I got with plating!!! Bob. Geoff Croker On You Tube does some excellent explaining of electroplating and some good 'How To' vids as well!
Tim
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Post by 92220 on May 19, 2019 17:15:27 GMT
Thanks Tim. Very interesting to see his results,
Bob.
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Post by Roger on May 19, 2019 19:20:14 GMT
My instinct is that electroplating a safety valve cover in brass is probably not a good idea. If the shape was more complex and difficult to make another way, it might make sense though. I think it's probably best to make it from two parts Silver Soldered together.
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Post by Roger on May 20, 2019 21:23:48 GMT
Yet another iteration of the water level arm, this time I've had to add a joggle to the arm because it was too close to the inner wrapper. 3D printing using supports for a flat surface leaves a horrible mess where the last layer of the support attaches. This needs to be removed so I've opted to machine it. PLA melts extremely easily, so I've used a new cutter with very slow RPM indeed and only 5mm/min feed rate. 20190520_095309 by Anne Froud, on Flickr I made some more modifications to the end plate design to add a bigger clearance for the bevel gear on the inside and a blind threaded hole for the bottom dummy test cock. The inner wrapper has been trimmed back to allow the 6mm thick end plate to sit further in. 20190520_161659 by Anne Froud, on Flickr If you peer deep into the bottom of the tank you can see how tight this all is. The LH side of the quadrant only just misses the inner wrapper in this position because I've filed it away at that point. 20190520_161834 by Anne Froud, on Flickr This is it in the other position, you can see why the joggle was necessary because it would hit the inner wrapper. You may be wondering why I didn't just move the whole thing further away from the inside. Even as it is, the test cocks are slightly too far inboard so I didn't want to have them even further out. The gear has to be this side because otherwise it won't rotate in the clockwise direction as it fills up, which is how it logically would work to my mind. 20190520_162010 by Anne Froud, on Flickr I cut a piece of Expanded Polystyrene as a test float and tried it in the sink to see if it was enough to lift the arm. That didn't work, the arm was too heavy for the size of the float. There was room for a bigger float, so for an experiment I decided to 3D print one that would have a slot through it for the arm. That was sufficient to lift the arm, but I think it could use a little more buoyancy so I'm printing one that's 6mm longer. The float is printed with a 5% fill and two perimeters with 0.2mm layer height so it's pretty light but plenty strong enough. During the experiments it didn't take on enough water to hear it if I shook the float, so I think it's going to be possible to make it water tight. It may be good enough as it is, but I might have to paint it to make sure. I could weight it, then completely submerge it for a week and then weigh it again. Anyway, this is how it looks when the tank is full... 20190520_200416 by Anne Froud, on Flickr ... and when it's empty. 20190520_200433 by Anne Froud, on Flickr The arm is quite heavy, so I'm pretty confident that this is going to provide enough force to ensure it will continue to work even when it's been in service for some time. The axial position of the arm is now set more closely so that the amount the gears engage is more closely controlled. They can't mesh too deeply and snag, they also can't wander too far out of mesh. I need to make the 3mm square Brass curved piece to hold the 6mm thick end plate in position next. Once that's done, there's only the end plate to machine when the Brass arrives and then I can assemble it all.
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Post by chris vine on May 21, 2019 15:36:17 GMT
Hi Roger,
I love your level indicator. Very cute.
My only thought is that your indicator pointer looks like a small handle on a valve. I am pretty sure that someone (in ignorance) will try to turn it!!
Chris.
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Post by andyhigham on May 21, 2019 16:07:52 GMT
Hi Roger, I love your level indicator. Very cute. My only thought is that your indicator pointer looks like a small handle on a valve. I am pretty sure that someone (in ignorance) will try to turn it!! Chris. Not a problem with the magnetic coupling
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