Kerr Stewart 4420 - Live steam and 3D printing
- -steves-
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Re: Kerr Stewart 4420 - Live steam and 3D printing
Trevor, are you using different temp solder for each stage to stop the pervious solder melting? If so what are you using and where from? If not, how do you do it without the previous solder work just falling apart??
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Re: Kerr Stewart 4420 - Live steam and 3D printing
Glad you like it! That encourages me to keep going!-steves- wrote: ↑Sun Jan 23, 2022 11:22 am Trevor, I am loving these "moving shots" where you show the work being done and give an idea of how these things are made rather than just producing a picture of the part finished, great stuff, keep up the good work.
I often read your posts but don't respond often, but please don't think it's going unnoticed as I look forward to seeing your threads updated
Trevor
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Re: Kerr Stewart 4420 - Live steam and 3D printing
That was what I was expecting!SimonWood wrote: ↑Mon Jan 24, 2022 9:09 am Didn't quite get what you meant about the slots from your post on Thurs, but seeing the pics from yesterday that does look like a really good solution.
Clearly the soldering on this is advanced stuff! When I get to this stage I think I will be knocking on your door for some help
Trevor
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Re: Kerr Stewart 4420 - Live steam and 3D printing
No I am not using different temperature solders - that is a technique which could be used - but I don't find it necessary.
I suppose a bit more detailed explanation is in order:
When a joint has been silver soldered then the combined materials seem to need a higher temperature for the solder to reflow. I seem to remember reading that somewhere in the distant past. In this case, just to make sure I placed the bare barrel on its side so one flat plate was uppermost. The idea was that if the plate came free I hoped it would stay where it was. I thought the lower plate was unlikely to get hot enough to have any chance of the solder melting. The stays, 3mm diameter, were a reasonably tight fit in the 3mm diameter holes. Sufficiently tight that I hoped they would stay in place. So I tried to concentrate the heat on one stay end at a time - not easy with a huge flame roaring away. Perhaps I should mention that this requires a high pressure torch connected to a calor gas propane cylinder. Such a torch does not have a normal pressure regulator like you get for a BBQ - but something which can be varied - and it really is high pressure. The big cylinder is also necessary because its the only way to provide gas at the required rate for this length of time. Perhaps I should try to get a photo of this for the next stage.
Anyway back to the main point - when it is eventually hot enough - the stays can be soldered one at a time. A matter of getting the solder to flow around the one stay - while the rest isn't quite hot enough. Then move to the next, taking advantage of the whole thing being almost red hot. Then when they have all been soldered, let it cool a little, to make sure nothing is close to the melting temperature, turn it over with tongues, and solder the stays on the other side, trying to take advantage of the whole thing still being pretty hot.
The challenge will be to get the end plates hot enough to solder. Not fear of the rest becoming unsoldered - just straight forward can I get it hot enough!
I am using the silver solder which is sold by Mac Models, they only have the one type on their website, and easy flow flux which they also sell.
By the way, I find the above much more difficult to do with ordinary solder - the type you would use for plumbing joints. A gas torch gets things too hot too readily, and it all falls apart. That is much easier with some form of hot bit.
So for both types of soldering I think it is really about balancing the rate that heat is entering the job, and the rate heat is leaving, so that you can just get it hot enough for the solder to flow, and when you remove the heat it solidifies quickly.
Trevor
- -steves-
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Re: Kerr Stewart 4420 - Live steam and 3D printing
Thanks Trevor, just the answer I was looking forTrevor Thompson wrote: ↑Mon Jan 24, 2022 7:38 pmNo I am not using different temperature solders - that is a technique which could be used - but I don't find it necessary.
I suppose a bit more detailed explanation is in order:
When a joint has been silver soldered then the combined materials seem to need a higher temperature for the solder to reflow. I seem to remember reading that somewhere in the distant past. In this case, just to make sure I placed the bare barrel on its side so one flat plate was uppermost. The idea was that if the plate came free I hoped it would stay where it was. I thought the lower plate was unlikely to get hot enough to have any chance of the solder melting. The stays, 3mm diameter, were a reasonably tight fit in the 3mm diameter holes. Sufficiently tight that I hoped they would stay in place. So I tried to concentrate the heat on one stay end at a time - not easy with a huge flame roaring away. Perhaps I should mention that this requires a high pressure torch connected to a calor gas propane cylinder. Such a torch does not have a normal pressure regulator like you get for a BBQ - but something which can be varied - and it really is high pressure. The big cylinder is also necessary because its the only way to provide gas at the required rate for this length of time. Perhaps I should try to get a photo of this for the next stage.
Anyway back to the main point - when it is eventually hot enough - the stays can be soldered one at a time. A matter of getting the solder to flow around the one stay - while the rest isn't quite hot enough. Then move to the next, taking advantage of the whole thing being almost red hot. Then when they have all been soldered, let it cool a little, to make sure nothing is close to the melting temperature, turn it over with tongues, and solder the stays on the other side, trying to take advantage of the whole thing still being pretty hot.
The challenge will be to get the end plates hot enough to solder. Not fear of the rest becoming unsoldered - just straight forward can I get it hot enough!
I am using the silver solder which is sold by Mac Models, they only have the one type on their website, and easy flow flux which they also sell.
By the way, I find the above much more difficult to do with ordinary solder - the type you would use for plumbing joints. A gas torch gets things too hot too readily, and it all falls apart. That is much easier with some form of hot bit.
So for both types of soldering I think it is really about balancing the rate that heat is entering the job, and the rate heat is leaving, so that you can just get it hot enough for the solder to flow, and when you remove the heat it solidifies quickly.
Trevor
I have done lots of silver soldering and have a couple of Sievert torches and a couple of 25kg gas bottles too which I use. I have never silver soldered a boiler, but I do have a couple to do in 3 1/2" gauge, so any advise is more than welcome
The buck stops here .......
Ditton Meadow Light Railway (DMLR)
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Re: Kerr Stewart 4420 - Live steam and 3D printing
I will be interested to hear how you get on with the 31/2 inch gauge boiler.
That is beyond my experience!
There are lots of people in the model engineering world who would be much better placed to offer advice for that. However one of the best things is to have a go. It is only by overcoming problems that our skills get better.
Trevor
That is beyond my experience!
There are lots of people in the model engineering world who would be much better placed to offer advice for that. However one of the best things is to have a go. It is only by overcoming problems that our skills get better.
Trevor
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Re: Kerr Stewart 4420 - Live steam and 3D printing
I am dreading starting that boiler, I have looked at it loads of times and then just put it back in the box. It's to go in one of these, a nice little Canterbury Lamb "Invicta"Trevor Thompson wrote: ↑Tue Jan 25, 2022 9:45 am I will be interested to hear how you get on with the 31/2 inch gauge boiler.
That is beyond my experience!
There are lots of people in the model engineering world who would be much better placed to offer advice for that. However one of the best things is to have a go. It is only by overcoming problems that our skills get better.
Trevor
The buck stops here .......
Ditton Meadow Light Railway (DMLR)
Member of Peterborough and District Association
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Re: Kerr Stewart 4420 - Live steam and 3D printing
Wow, I am still looking for one of those.
I already have a Rainhill and two Tiches.
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Re: Kerr Stewart 4420 - Live steam and 3D printing
I understand the feeling.
You have a suitable torch - just go for it!!!!
Trevor
You have a suitable torch - just go for it!!!!
Trevor
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Re: Kerr Stewart 4420 - Live steam and 3D printing
I have made some slight progress on the boiler.
I made a wooden former for the end caps. It consists of a rectangular block and a circular block cut in half and each half glued onto the ends of the block. It has worked so far - but I really need to remake it from a solid offcut of hardwood which I found in the workshop.
A piece of copper sheet, cut oversize, has been repeatedly annealed and bent to get to the point where it is almost the right shape:
It needs trimming to size and a final few attempts so get the curved ends just right.
Trevor
I made a wooden former for the end caps. It consists of a rectangular block and a circular block cut in half and each half glued onto the ends of the block. It has worked so far - but I really need to remake it from a solid offcut of hardwood which I found in the workshop.
A piece of copper sheet, cut oversize, has been repeatedly annealed and bent to get to the point where it is almost the right shape:
It needs trimming to size and a final few attempts so get the curved ends just right.
Trevor
- -steves-
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Re: Kerr Stewart 4420 - Live steam and 3D printing
Someone has been very busy with all these updates to 3 projects, love it
The buck stops here .......
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Re: Kerr Stewart 4420 - Live steam and 3D printing
It is good to have something to do when the weather is as bad is it has been the last week or so. We were lucky not to lose power or phone on a number of occasions!
Trevor
Trevor
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Re: Kerr Stewart 4420 - Live steam and 3D printing
Unfortunately we did lose power on Friday... all day and evening, so no chance of any modelling then... (sorry for thread drift)Trevor Thompson wrote: ↑Mon Feb 21, 2022 8:20 pm It is good to have something to do when the weather is as bad is it has been the last week or so. We were lucky not to lose power or phone on a number of occasions!
Trevor
The best things in life are free.... so why am I doing this?
Re: Kerr Stewart 4420 - Live steam and 3D printing
I did lose power daytime on Friday - ended up working in the shed. And I don't mean working on the railway which I might normally do in the shed, I mean the what-they-pay-you-for work, i.e. trying to use MS Teams on my phone because the shed was the only place with a mobile signal when the wifi was off...
When power came back I was cocky enough to assume it was back for good - and started printing some wheels! Only just completed before the power cut out again for the rest of the evening. With cuts all weekend, I didn't try printing again until things died down on Monday!
(Also I still haven't assembled my 4420 chassis, the ABS rafts either stick to the bed or the the model, either way it takes a long time to separate and sometimes the process is so destructive I have to reprint! Should probably have gone for PLA, printing ABS is particularly difficult when the weather is cold. Nearly there though...)
When power came back I was cocky enough to assume it was back for good - and started printing some wheels! Only just completed before the power cut out again for the rest of the evening. With cuts all weekend, I didn't try printing again until things died down on Monday!
(Also I still haven't assembled my 4420 chassis, the ABS rafts either stick to the bed or the the model, either way it takes a long time to separate and sometimes the process is so destructive I have to reprint! Should probably have gone for PLA, printing ABS is particularly difficult when the weather is cold. Nearly there though...)
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Re: Kerr Stewart 4420 - Live steam and 3D printing
Simon
A tip.
Always lift the model 1 mm off the bed before adding supports.
Then when the print is finished you can separate the model from the raft easily. Then you can carefully remove the raft from the bed. This way you don't have to try to avoid damaging the bed and the model at the same time.
Stick with ABS. Its a better quality plastic.
I have solved another problem with printing in ABS which I will describe later.
Trevor
A tip.
Always lift the model 1 mm off the bed before adding supports.
Then when the print is finished you can separate the model from the raft easily. Then you can carefully remove the raft from the bed. This way you don't have to try to avoid damaging the bed and the model at the same time.
Stick with ABS. Its a better quality plastic.
I have solved another problem with printing in ABS which I will describe later.
Trevor
Re: Kerr Stewart 4420 - Live steam and 3D printing
Thank you - I have reprinted the inner frame using this tip and the damage is much more minimal (and easily repairable).Trevor Thompson wrote: ↑Thu Feb 24, 2022 9:38 am Always lift the model 1 mm off the bed before adding supports.
Then when the print is finished you can separate the model from the raft easily. Then you can carefully remove the raft from the bed. This way you don't have to try to avoid damaging the bed and the model at the same time.
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Re: Kerr Stewart 4420 - Live steam and 3D printing
I have done some more on the boiler.
The inside parts of the two tubes have been ground down to allow the flanged end plate to slot in:
The flanged end plate is finished, and drilled and it fits (where it touches):
The large hole is for the burner tube, the small one for a stay, and the other for the steam take off. Yes there are gaps at the sides - but the curved parts which fit properly were silver soldered. Then it was pickled to clean the flux off and the gap gently closed up with a hammer. The sides were then silver soldered:
I think that looks like a good soldered joint. So on to making the front flanged plate.
Trevor
The inside parts of the two tubes have been ground down to allow the flanged end plate to slot in:
The flanged end plate is finished, and drilled and it fits (where it touches):
The large hole is for the burner tube, the small one for a stay, and the other for the steam take off. Yes there are gaps at the sides - but the curved parts which fit properly were silver soldered. Then it was pickled to clean the flux off and the gap gently closed up with a hammer. The sides were then silver soldered:
I think that looks like a good soldered joint. So on to making the front flanged plate.
Trevor
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Re: Kerr Stewart 4420 - Live steam and 3D printing
Beautiful work as always, Trevor!
This loco really is something special.
This loco really is something special.
Regards,
Aaron - Scum Class Works
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Re: Kerr Stewart 4420 - Live steam and 3D printing
I'm back to working on this one again. I think it is time to see if it can be made to work.
The boiler is finished, a second flanged plate for the front end, the tube for the burner inserted, the stay in, and the bronze bushes in place. I have made up feet to support the boiler clear of the plastic footplate. All soldered up ready to pressurise it to see if it holds water:
You can see the PTFE top hat bushes between the boiler feet and the footplate in the first photo. I am hoping that there will be enough room between the motor and the boiler to get the jet out when it gets blocked.
I have drawn up the bodywork and printed out the parts. It is s strange looking beast for a steam locomotive!
The body is just sitting there loose at the moment. I wanted to get some sort of attempt at the bodywork so I could make sure that I was fixing the boiler in the right place. I think some adjustments will be needed for the smokebox end of the body to make sufficient clearance for the flue.
And that is 4415 sitting in the background - which shows the similarities and differences between the two locomotives.
Trevor
The boiler is finished, a second flanged plate for the front end, the tube for the burner inserted, the stay in, and the bronze bushes in place. I have made up feet to support the boiler clear of the plastic footplate. All soldered up ready to pressurise it to see if it holds water:
You can see the PTFE top hat bushes between the boiler feet and the footplate in the first photo. I am hoping that there will be enough room between the motor and the boiler to get the jet out when it gets blocked.
I have drawn up the bodywork and printed out the parts. It is s strange looking beast for a steam locomotive!
The body is just sitting there loose at the moment. I wanted to get some sort of attempt at the bodywork so I could make sure that I was fixing the boiler in the right place. I think some adjustments will be needed for the smokebox end of the body to make sufficient clearance for the flue.
And that is 4415 sitting in the background - which shows the similarities and differences between the two locomotives.
Trevor
Re: Kerr Stewart 4420 - Live steam and 3D printing
Fantastic.
How did you make the PTFE boiler feet? Turned on the lathe?
Really interesting to see the bodywork. It is a strange looking loco, but while it's hard to deny it looks like it's had an encounter with the ugly stick, it's actually far more appealing to my eye than drawings suggested to me.
I know it's not your plan to, but looks like there's lots of room in the tanks if one were to R/C it (reverser linkage running under the cab floor perhaps?)
How did you make the PTFE boiler feet? Turned on the lathe?
Really interesting to see the bodywork. It is a strange looking loco, but while it's hard to deny it looks like it's had an encounter with the ugly stick, it's actually far more appealing to my eye than drawings suggested to me.
I know it's not your plan to, but looks like there's lots of room in the tanks if one were to R/C it (reverser linkage running under the cab floor perhaps?)
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