Garden Railway Forum

Trevor Thompson wrote: ↑Fri Jan 07, 2022 12:34 pm I now have a running chassis. The steam motor is easily removable by undoing two nuts and bolts, and the chains are all connected.

I have added video of it running on compressed air at 20psi. The reverser does allow good control of both direction and speed - and I am sure could be controlled by a servo.

SimonWood wrote: ↑Mon Jan 10, 2022 7:37 pm

Trevor Thompson wrote: ↑Fri Jan 07, 2022 12:34 pm I now have a running chassis. The steam motor is easily removable by undoing two nuts and bolts, and the chains are all connected.

I have added video of it running on compressed air at 20psi. The reverser does allow good control of both direction and speed - and I am sure could be controlled by a servo.

Terrific! Very controlled. This whole project just gets more and more exciting.

Trevor Thompson wrote: ↑Tue Jan 11, 2022 9:59 am How are you getting on with the chassis?

-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

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

-steves- wrote: ↑Mon Jan 24, 2022 1:12 pm 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??

Trevor Thompson wrote: ↑Mon Jan 24, 2022 7:38 pm

-steves- wrote: ↑Mon Jan 24, 2022 1:12 pm 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??

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

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

-steves- wrote: ↑Tue Jan 25, 2022 12:50 pm
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"

Canterbury_Lamb_001.jpg