buying v getting cast blocks

[92220]

Just to show how a lot of silversolder joints can be made, these are some photos of the making of my cylinders. All joints were silversoldered using Easyflo No.2 and in a number of consecutive heatings.

cylinder parts 003 by Robert Shephard, on Flickr


cylinder assembly 006 by Robert Shephard, on Flickr


cylinder assembly with rear steamchest cover 001 by Robert Shephard, on Flickr


Bob.

[Roger]

Jul 1, 2022 8:32:28 GMT 92220 said:

Jun 30, 2022 19:35:09 GMT silverfox said:

Update


Bob Getting the steam passages from bore to valve looks like a problem or do you have athick piece of bms at each ens say 3/4 in
Would yo then have a larger bore at each end to take the CI and then open out that to finished size?

Pieces of pipe can be silversoldered in for the passageways, or any other method of connection that suits. Multiple silversolderings can be done because when silversolder gets melted, it's melting point goes up, so an adjacent silversoldered joint can be done without re-melting the previous joint. When I made my scale shape cylinders, I did 25 or 30 separate joints for each cylinder. When I fabricated the underframe for the cab, there were 32 separate silversoldred joints, and none remelted when the next joint was made. The construction was all in 20swg steel sheet. If worried about re-melting, CUP can supply various melting point silversolders. Oxy propane or oxy acetylene, rather than overall heating helps with multi joint assemblies too, because the heat is much more concentrated. I did show the cylinder construction on my Evening Star thread (page 1)

Bob.

Hi Bob,
I don't think you're right about the progressive raising of the melting point. That's only true of copper because it alloys with the silver solder, increasing the copper content of the alloyed joint material. That can't happen when the material you're silver soldering is steel.
I think you can get away with consecutive silver soldering steps only because you aren't completely re-melting the whole of any of the preceding joints. Personally, I'd use different higher temperature silver solders for the first operations.

[melaser]

UCB Ferrocast in Chesterfield you want for iron, they supply pretty much everyone else so cut out the middleman

[johnd]

Dan,
Excuse my cynicism but could it be that most people purchase the gunmetal set of castings therefore they put a premium on popularity.
In my case i have always shied away from cast iron, like a lot of friends,as i use my locos only a couple of times a year and i have always worried about corrosion gumming up the cylinders, ports etc.
Therefore i have always purchased gunmetal casting kits, but i am taking a leap, for me, of using cast iron solid blocks this tim. Will report back when i start to machine, with a few photos if possible.

[Roger]

Jul 3, 2022 17:37:42 GMT johnd said:

Dan,
Excuse my cynicism but could it be that most people purchase the gunmetal set of castings therefore they put a premium on popularity.
In my case i have always shied away from cast iron, like a lot of friends,as i use my locos only a couple of times a year and i have always worried about corrosion gumming up the cylinders, ports etc.
Therefore i have always purchased gunmetal casting kits, but i am taking a leap, for me, of using cast iron solid blocks this tim. Will report back when i start to machine, with a few photos if possible.

Corrosion is the biggest issue with CI, and that also put me off using it.
Take a look at the price of SAE660 Leaded Bronze. I machined my cylinders from a piece of round bar from Leeds Bronze, and it was very reasonable.

[92220]

Hi Roger.

I wondered if I had got it wrong, so I put the question to CUP Alloys. This is what I got back from them, which confirms what I had thought I had read on another website....I think it was the Johnson Matthey website some years ago, though am not sure:-

.....................

Hi Mr Shephard.

In a correctly formed joint with full capillary penetration the brazing alloy ‘mixes’ with the parent metal at the joint interface. So yes it’s remelt temperature is slightly higher than it’s original melting temperature.
It is therefor theoretically possible to to produce joints in close proximity to each other with the same brazing alloy once the previous joint has fully cooled.
However, the heating must be controlled as we are only talking perhaps 20-30 degrees and so for very close joints we would recommend step brazing with different temperature brazing alloys.

Kind regards.

.......................

I put the question, for use with both copper and steel, of whether silversolder melting temp increases after melting. I didn't remelt the original joints. That was the whole idea behind the raising of the melting point. As Shaun said, you do have to be careful though because it isn't a great rise in temp.

Bob

[silverfox]

Bob

If i could produce a cylinder like that i wouldn't put any cladding around it

Ron

[millman]

I will go a bit further, if I made a cylinder like that it would go in a glass case on the mantelpiece.

[92220]

Thanks guys, but it was just made as all the other bits for the loco. With an almost full set of works detail and assembly drawings (now around the 800 mark), I am making everything to scaled down drawings where possible within the limitations of scale. It is a very long job and to keep up the enthusiasm for the project, every part is treated as a separate job....small or large.

Bob.

[Roger]

Jul 4, 2022 7:29:41 GMT 92220 said:

Hi Roger.

I wondered if I had got it wrong, so I put the question to CUP Alloys. This is what I got back from them, which confirms what I had thought I had read on another website....I think it was the Johnson Matthey website some years ago, though am not sure:-

.....................

Hi Mr Shephard.

In a correctly formed joint with full capillary penetration the brazing alloy ‘mixes’ with the parent metal at the joint interface. So yes it’s remelt temperature is slightly higher than it’s original melting temperature.
It is therefor theoretically possible to to produce joints in close proximity to each other with the same brazing alloy once the previous joint has fully cooled.
However, the heating must be controlled as we are only talking perhaps 20-30 degrees and so for very close joints we would recommend step brazing with different temperature brazing alloys.

Kind regards.

.......................

I put the question, for use with both copper and steel, of whether silversolder melting temp increases after melting. I didn't remelt the original joints. That was the whole idea behind the raising of the melting point. As Shaun said, you do have to be careful though because it isn't a great rise in temp.

Bob

Hi Bob,
Interesting. Googling this further, it does appear that Iron will form an alloy with Silver, so this possibly does attract some of the Silver in the Silver Solder, raising the melting point. However, I can't find anything to give a measure of how much this actually happens, if at all.
The safest thing is to assume that it doesn't make any difference, and use different grades of Silver Solder in my opinion.

[Neale]

Didn't a recent Model Engineer article discuss this? I vaguely remember that it's all to do with (apart from the metal-in-metal solution at the surface molecular level) eutectic mixtures and things coming out of solution before others. Or something - it's all a bit complicated! In practice, though, the effect seems significant enough that it is well-used although my own experience of trying to manage silver-soldering temperatures would make me worry about remelting adjacent joints. On the other hand, my limited experience suggests that silver-soldering isn't quite as difficult or needing such extensive preparation as some people suggest, so maybe if I tried it, it would work!

[Roger]

Jul 4, 2022 16:35:50 GMT Neale said:

Didn't a recent Model Engineer article discuss this? I vaguely remember that it's all to do with (apart from the metal-in-metal solution at the surface molecular level) eutectic mixtures and things coming out of solution before others. Or something - it's all a bit complicated! In practice, though, the effect seems significant enough that it is well-used although my own experience of trying to manage silver-soldering temperatures would make me worry about remelting adjacent joints. On the other hand, my limited experience suggests that silver-soldering isn't quite as difficult or needing such extensive preparation as some people suggest, so maybe if I tried it, it would work!

When it comes to preparation for Silver Soldering, you can spend time and have very little to clean up afterwards, or not bother and spend the time afterwards removing the excess Solder and re-heat to get it where it didn't want to flow. Either way takes about the same amount of time in my experience, so the choice is yours. Personally, I like to do a lot of preparation and get the required amount of Solder exactly where I want it and nowhere else. It's not that it's difficult, it's just that it takes preparation to control where the Solder flows.

[Neale]

Roger - I think there's enough material here for another thread or two on silver-soldering techniques (although I'm sure it must have been done...)! Don't want to continue discussion on this one here as it's not directly relevant to OP. The original question was castings versus another subtractive machining technique - start with solid block and machine - but additive method of building up by silver-soldering clearly can give very nice results. Cost versus time argument here? And are material cost increases changing the balance?

[johnd]

“…………………Corrosion is the biggest issue with CI, and that also put me off using it.
Take a look at the price of SAE660 Leaded Bronze. I machined my cylinders from a piece of round bar from Leeds Bronze, and it was very reasonable.”

Roger,
Would you recommend Sae660 grade rather than LG2 for cylinders?

[Roger]

Jul 6, 2022 11:00:32 GMT johnd said:

“…………………Corrosion is the biggest issue with CI, and that also put me off using it.
Take a look at the price of SAE660 Leaded Bronze. I machined my cylinders from a piece of round bar from Leeds Bronze, and it was very reasonable.”

Roger,
Would you recommend Sae660 grade rather than LG2 for cylinders?

I don't know if one is peferable to the other to be honest. I don't know if you can get bar stock of LG2, but you definitely can get SAE660. Since I haven't run my locomotive on Steam, I can't say how good or bad it is compared to anything else. The price is good if you shop around. I'd definitely get three quotes before buying because they vary a lot. It seems like a perfectly reasonable choice to me, but others may have a different opinion. I've used this material for Air Bearings for decades, and it's used because of its ability to take light metal to metal contact with the Stainless Steel shaft in those without siezing. It's easy to work with and is much less 'grumbly' than CI which is easy to strip threads in.

[silverfox]

John

SAE660..
Every site i have looked a\,willing to be proved wrong, doesn't give sizes or prices, just specs

Any hints on who may be more user friendly?

Ron

[johnd]

Rodger,

Thanks for your info, I have used SAE660 and its great to work with.

Ron,

M-Machine metals online has a downloadable lists showing round in SAE660 & LG2 also Square in LG2 with prices per inch.

[Roger]

Check out Leeds Bronze, just email them with your bar diameter and length for a quote.  You almost certainly won't find a list of prices for this sort of item.

also see 

East Midland Alloys & Metals 

[e-mail] 

Bronze SAE660

102mm dia x 170mm long £101.00

carriage £18.00

It turns out I used these, not Leeds Bronze. This was back in July 2017

[jasonb]

Don't forget you can also get SA660 in hollow section, why pay for the bit you are going to bore out the middle. Depending on how you are going to proceed a thicker wall one will suit carving the outside, thinner wall if soldering on pieces for flanges and valve block.

I've used 660 on several engines using the built up method, tend to use CI for ones I cut from solid as it's easier to join the 660 than it is CI. This is the great advantage of using bronze, even if you carve most of teh cylinder from solid it is a lot easier to solder on small features such as webs or drain cock bosses then trying to mill them.

Another option is to pick up odd cylinder castings cheaply and chop them about to suite, this cylinder casting cost me £5 (4 for £20) at a show



and gave me this



No castings on this one

[Gary L]

Jul 6, 2022 11:00:32 GMT johnd said:

“…………………Corrosion is the biggest issue with CI, and that also put me off using it.
Take a look at the price of SAE660 Leaded Bronze. I machined my cylinders from a piece of round bar from Leeds Bronze, and it was very reasonable.”

Roger,
Would you recommend Sae660 grade rather than LG2 for cylinders?

More by luck than planning, all the steam engine cylinders (5 sets) I have ever owned have been CI. I’ve never had a problem with corrosion of the CI. I don’t steam regularly, they are often left standing for months at a time. So I think the issue is very much overrated, YMMV. The (graphite?) ‘pores’ in it mean CI is a first-class bearing material. It has been used in literally innumerable cylinders, steam and otherwise, for centuries, and is still the material of choice. I think the pores must mean it also retains enough cylinder oil to keep corrosion at bay. Yes, I know that if I get water on my CI mill table I quickly get rust, but it doesn’t seem to happen inside cylinders; I leave it to someone else to explain why.

I’m not very convinced by the various alternatives put forward for piston rings in bronze cylinders. I daresay some will be OK (I’ve not been interested enough to investigate) but it is very hard to imagine any will have the empirically proven long term durability of CI rings in CI cylinders.

Two caveats. Of late I always give a squirt of WD40 up the draincocks after running, followed by a few yards pushing with drains open to help the WD40 disperse the water. Plainly it hasn’t done any harm, but one account I’ve read suggests it may not help a lot either, because there is already enough steam oil in the CI to do the job. I don’t know. A D10 I made at school hasn’t been steamed in years, and it never had any WD40 squirts either, but it still turns over as smoothly as ever.

Secondly, this only applies to CI not steel. I did have the steel valve bobbins seize in a Speedy, a result of a hydraulic test with no subsequent precautions before I bought it. Investigation showed the CI bores were fine, but the bobbins had to be replaced (I used bronze and PTFE since the porting did not allow CI rings). I wouldn’t use anything other than CI and CI rings for pistons in CI cylinders.

Other respected people obviously have different opinions, but starting from scratch I wouldn’t personally entertain the enormous cost of bronze for benefits that are unclear.

HTH

Gary