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Post by David on Dec 8, 2019 22:46:03 GMT
I always thought heating a plate of metal red hot would make it distort. I guess it still might but won't distort as much during later machining due to what you say about the changes to the internal structure.
If you stick the plate down on the magnetic vise after heating will the vise hold it flat while you fly cut it and then it gets its little undulations back when you let off the magnetic field?
I tried to make my slidebars from BMS because it would have meant much less surface finishing. I knew they'd likely bend - and they did - but it was good to see it first hand to see how much it can distort.
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Post by Roger on Dec 8, 2019 23:36:03 GMT
I always thought heating a plate of metal red hot would make it distort. I guess it still might but won't distort as much during later machining due to what you say about the changes to the internal structure. If you stick the plate down on the magnetic vise after heating will the vise hold it flat while you fly cut it and then it gets its little undulations back when you let off the magnetic field? I tried to make my slidebars from BMS because it would have meant much less surface finishing. I knew they'd likely bend - and they did - but it was good to see it first hand to see how much it can distort. It's certainly possible that heating it might distort the plate, but as yet I've not found that to be a problem with Steel. Heat a piece of Brass plate and it will probably be a very different matter. You don't want to hold anything down that's distorted, either with a magnetic chuck or clamps. If it's warped, it needs to be bent back so it at least sits down without rocking. That usually means choosing to place it with the hump in the middle away from the chuck. The idea is to hold it without bending it, else it's going to be bent when you release the clamp or magnetic chuck. Once you've machined that reference surface, you can then clamp it down tightly on that face. You can get undulations with conventional magnetic chucks on thin parts, and this is why I bought a fine pole chuck. We used to have issues with this in Air Bearing Thrust Plates, but after switching to this type of chuck the problem was solved. I think you have to view any Cold Rolled plate or bar with suspicion if you're going to machine a precision part. You really need to Normalise it to be sure it's not going to move. In my opinion, short cuts just waste time and materials in the long run.
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jma1009
Elder Statesman
Posts: 5,901
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Post by jma1009 on Dec 8, 2019 23:50:27 GMT
As an alternative to Roger's method for the cab base plate, I would have hacksawed out the base from steel sheet, then filed up to size, then silver soldered on the steel strips on the sides. I would probably do the cab base in 3 or more sections as the middle section might require removal to get to what is underneath, and without disturbing the rear bunker.
If I wanted to add more weight to the rear, other considerations would apply, and I vaguely recall adding a nice fitting bit of 1/4" plate to underneath the cab plate/footplate of my first loco.
Cheers, Julian
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stevep
Elder Statesman
Posts: 1,070
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Post by stevep on Dec 9, 2019 9:03:16 GMT
Roger, you say that you have machined all the pieces with no clearance.
Is the cut-out at the top of your last picture behind the back-head of the boiler? You ought to leave some clearance for expansion - assuming you are following the normal path of having the front of the boiler rigidly connected to the smokebox, and allowing the boiler to expand to the rear of the locomotive.
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Post by Roger on Dec 9, 2019 9:11:16 GMT
Roger, you say that you have machined all the pieces with no clearance. Is the cut-out at the top of your last picture behind the back-head of the boiler? You ought to leave some clearance for expansion - assuming you are following the normal path of having the front of the boiler rigidly connected to the smokebox, and allowing the boiler to expand to the rear of the locomotive. Hi Steve, There's a lot of clearance behind the backhead, it's only the chequer plates that are size for size at the moment. The cab base is going to be painted, but I thought I'd Black the plates and use a rust preventative product I've got on top of that.
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Post by Roger on Dec 9, 2019 9:22:36 GMT
As an alternative to Roger's method for the cab base plate, I would have hacksawed out the base from steel sheet, then filed up to size, then silver soldered on the steel strips on the sides. I would probably do the cab base in 3 or more sections as the middle section might require removal to get to what is underneath, and without disturbing the rear bunker. If I wanted to add more weight to the rear, other considerations would apply, and I vaguely recall adding a nice fitting bit of 1/4" plate to underneath the cab plate/footplate of my first loco. Cheers, Julian Hi Julian, I certainly wouldn't recommend my solution unless you've got a chunky CNC machine. The weight of the cab floor is no more than it would be if made from plate as you describe, that wasn't the reason for doing it. The main motivation was to make the vertical edges very strong and to get that reduced thickness on the edge. It does end up very stiff too, which is useful since the reverser is bolted to the cab floor, not the frames, it's too far outboard for that. The substantial bracket for the steps and the one at the front conventiently line up with the two end bolts of the reverser though, so it's pretty strong. If I was fabricating the edge pieces, I think I'd make them oversize and screw them down with very small bolts before Silver Soldering. Then I'd machine them on the outside to get it all square and true. How flat it would all end up is hard to say. It would probably be a good idea to Normalise the plate before Silver Soldering and making sure it was flat before adding the edge pieces. Once they were on, it would hard to straighten it out. It did consider fabricating this, but to be honest I don't think it would have been much quicker. I've got a massive 20mm thick stretcher under the cab floor for additional weight.
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Post by ettingtonliam on Dec 9, 2019 16:49:28 GMT
As an alternative to Roger's method for the cab base plate, I would have hacksawed out the base from steel sheet, then filed up to size, then silver soldered on the steel strips on the sides. I would probably do the cab base in 3 or more sections as the middle section might require removal to get to what is underneath, and without disturbing the rear bunker. If I wanted to add more weight to the rear, other considerations would apply, and I vaguely recall adding a nice fitting bit of 1/4" plate to underneath the cab plate/footplate of my first loco. Cheers, Julian So would I Julian, but then I don't have Roger's CNC equipment and the expertise in using it, so there would be no choice really. Richard
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Post by Roger on Dec 9, 2019 22:02:15 GMT
It doesn't appear from this that much has moved forward, but the two plinths are now bolted in position from underneath. That required setting them up on the mill and then adjusting the edges so they didn't foul the side of the cab base on the left, and the reverser on the right. The middle section of wooden boarding has been trimmed so it fits, and the two plates nearest the camera have also been filed to fit. It's all still very close, so they might need a little more clearance but it's fine for now. The plates at the back need a little work to get them to fit. They've come out slightly over size. 20191209_214944 by Timothy Froud, on Flickr Soon I'll have to decide on how I'm going to attach the plates. There are 1mm holes for M1 bolts, so that's one possible way to stop them from sliding. I'll need to find or make some M1 reduced head Steel bolts though, at the moment I can only get Brass ones and they won't look right. I might embed magnets in the plates, you can get them down to 1mm thick so that might work. It might just be that adding location pins where the M1 bolts are is all it takes to keep them in place. I could put a liberal smear of Silicone Grease under them to keep out any moisture and that would keep them in place too. Some could be permanently bonded in place, but I'm not keen on that idea because rust could form between the plates and the cab under floor.
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don9f
Statesman
Les Warnett 9F, Martin Evans “Jinty”, a part built “Austin 7” and now a part built Springbok B1.
Posts: 960
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Post by don9f on Dec 9, 2019 22:43:43 GMT
Hi Roger, what about countersunk screws? That is how I recall that sort of chequerplate being fastened down in the enginerooms of the older types of diesel locos. I think they are available in 1.0mm size stainless from Knupfer.....if that’s what “VA (Niro / A2)” means! linkCheers Don
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Post by jon38r80 on Dec 9, 2019 22:47:36 GMT
This "because rust could form between the plates and the cab under floor." made me think once more that maybe it would have been better to machine those plates that dont need to come off as part of the cab floor but then the thought occurs to me that the run time on all the checquer plate pieces that might be fixed would be very long indeed. It would solve your dilemma though. Have you considered a high performance double sided tape? . I have used it (3M) to fix cover plates on aluminium cladding to hide fixings on a building over 50 stories high and its still there thirty four years later.It might mess up your total thicknesses too much to be acceptable.
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Post by Roger on Dec 9, 2019 22:54:42 GMT
Hi Roger, what about countersunk screws? That is how I recall that sort of chequerplate being fastened down in the enginerooms of the older types of diesel locos. I think they are available in 1.0mm size stainless from Knupfer.....if that’s what “VA (Niro / A2)” means! linkCheers Don Hi Don, Thanks for that. They're definitely hex head bolts on 1501 so I'd like to keep that look. However, it might be that I can machine down the heads of screw like those in the link to have a reduced hex head. There might be just enough height left when the screw driver slot has been machined away. There appear to be quite a few available on eBay too.
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Post by ettingtonliam on Dec 10, 2019 0:08:41 GMT
Might that be because the restorers had hex head bolts but no countersunk ones? We certainly used to use countersunk when fitting non slip plates to overhead walkways and gantries in the steelworks.
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Post by Roger on Dec 10, 2019 8:08:05 GMT
Might that be because the restorers had hex head bolts but no countersunk ones? We certainly used to use countersunk when fitting non slip plates to overhead walkways and gantries in the steelworks. Possibly, but I'd like to fit what's there now since I'm modelling it as it is in restoration. In reality, they don't have to be threaded at all, I can just have a plain shank with a hex head. I've ordered some Cheese head screws, but everything in this size is either Brass or Stainless. I really need High Tensile if it's going to be threaded and Blacked, or just make them from Mild Steel. I could try to make them from Silver Steel, but I think it would end up a mass of burrs.
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Post by Roger on Dec 10, 2019 16:41:04 GMT
This "because rust could form between the plates and the cab under floor." made me think once more that maybe it would have been better to machine those plates that dont need to come off as part of the cab floor but then the thought occurs to me that the run time on all the checquer plate pieces that might be fixed would be very long indeed. It would solve your dilemma though. Have you considered a high performance double sided tape? . I have used it (3M) to fix cover plates on aluminium cladding to hide fixings on a building over 50 stories high and its still there thirty four years later.It might mess up your total thicknesses too much to be acceptable.
Hi Jon, I do need to be able to take off some of them to gain access to the bolts under them so I can't stick them all down. I certainly could do that with the others though. You're absolutely right about the run time for the chequer plate, and the other issue is holding it down flat enough over such a large area. In the end, as long as they're not bouncing around loose, I don't think it's going to be a problem keeping them in position. The plinths and inside of the raised edges keep some control over them, and if I use the bolt holes as locations then they can't slide around. I think I'd like to keep it so they can be removed, even if a little prying is required to get them out.
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Post by chris vine on Dec 10, 2019 16:49:19 GMT
Hi Roger,
Just thought for you. Your locomotive is going to be around for a long time. I am certain that it will be around long after you are gone. Maybe that sounds sad, but you have created something wonderful and it will last.
Maybe future generations will put it in a glass case, but maybe they will want to operate it as you intended it should be used. Bearing this in mind, I think you should provide some means of telling future owners/restorers which bolts are dummies and which are real. This will make dismantling much easier in the future, maybe even for yourself. Maybe you could put a mark on the heads to denote dummies?
For Bongo, I have written a set of notes describing which oils to use, the sequence to dismantle certain parts. EG brake valve which is difficult to remove from the engine.
Hoping you have a very long life!! Chris.
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Post by Cro on Dec 10, 2019 16:55:17 GMT
Hi Roger, Just thought for you. Your locomotive is going to be around for a long time. I am certain that it will be around long after you are gone. Maybe that sounds sad, but you have created something wonderful and it will last. Maybe future generations will put it in a glass case - I don't plan on it!, but maybe they will want to operate it as you intended it should be used. Bearing this in mind, I think you should provide some means of telling future owners/restorers which bolts are dummies and which are real. This will make dismantling much easier in the future, maybe even for yourself. Maybe you could put a mark on the heads to denote dummies? For Bongo, I have written a set of notes describing which oils to use, the sequence to dismantle certain parts. EG brake valve which is difficult to remove from the engine. - I look forward to reading the notes one day! Hoping you have a very long life!! Chris. Hopefully one day Roger will be able to turn this log into something tangible for the future as It's a gold mine of information on the loco itself and how it all goes together. Adam
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stevep
Elder Statesman
Posts: 1,070
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Post by stevep on Dec 10, 2019 17:09:44 GMT
I did a set of assembly/dismantling instructions for my Rob Roy. As it was over 30 years before I stripped some of it down, it was invaluable.
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Post by Roger on Dec 10, 2019 17:40:58 GMT
Hi Roger, Just thought for you. Your locomotive is going to be around for a long time. I am certain that it will be around long after you are gone. Maybe that sounds sad, but you have created something wonderful and it will last. Maybe future generations will put it in a glass case, but maybe they will want to operate it as you intended it should be used. Bearing this in mind, I think you should provide some means of telling future owners/restorers which bolts are dummies and which are real. This will make dismantling much easier in the future, maybe even for yourself. Maybe you could put a mark on the heads to denote dummies? For Bongo, I have written a set of notes describing which oils to use, the sequence to dismantle certain parts. EG brake valve which is difficult to remove from the engine. Hoping you have a very long life!! Chris. Hi Chris, This is something I've been pondering over for some time, because it really isn't obvious how some things come apart. My intention is to go back through all of the 3D mo del and create dimensioned drawings for everything. Much of that has already been done along the way, but not all of it. Obsolescence is a problem, so I thought I'd convert them to PDFs and maybe even print them out. That would be a big task though. I also want to document the special tools and also write some procedures for taking various pieces apart. This could take some time! In the end, I'd like it to be used and for whoever is the custodian should have as much information about it as possible to make life easy.
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JonL
Elder Statesman
WWSME (Wiltshire)
Posts: 2,907
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Post by JonL on Dec 10, 2019 20:58:56 GMT
There really is a book in all of this...I can put you in touch with a publisher, as I'm sure could Chris.... :-)
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Post by Roger on Dec 10, 2019 22:42:53 GMT
Here are the joining plates that attach the cab roof to the Spectacle Plate, Side Plates and Bunker Side Plates. I've made these from 1mm plate as they are structural parts. The side ones will be riveted on one half and filed flush. On 1501 these are welded in place. The other side is held with M1 bolts. The ones on the Spectacle Plate are held on by bolts only. That allows the plate to be removed completely. I think it's done like that so that the studs could be welded in place on the top and bottom halves of the Spectacle Plate because you can't get to the back of them to unscrew and remove them as the Pannier Tank butts up against them. 20191210_223452 by Timothy Froud, on Flickr
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