Member postings for Will Robertson

Hi Clive and Hansrudolf,

Thank you for correcting me. My guess at ASB was only a guess. I've had a look for EDS but I'm maybe using the http://www.brw.ch catalogue wrongly. I can find ECS and EDK but not EDS. Any help greatfully appreciated!

Thanks for the explaination on coarse and fine threads. So for a steam model am I right in thinking that there's general agreement that if metric threads are used then fine metric threads should be used for all threads on the model?

(Maybe I'm failing to understand the difference between fastners and fittings?)

Will

Hi Clive and Hansrudolf,

Now for that boring tool...

The rebuilt S50 will have a cylinder of c. 16mm diamiter and my engine a cylinder of c. 20mm diamiter and c.30mm long. Then I guessed that a boring bar with a V shaped point would be best for a cylinder so that lead me to

Ausbohrstahl IFANGER ASB Standard, Kobalt 2

at the bottom of this page

**LINK**

Is that the right guess or have I got things wrong?

Will

Hi Clive and Hansrudolf,

Looks like a bit of a controversy - Imech insist that if metric threads are used for steam models fine metric threads should be used but Clive uses standard threads. I don't have a good enough understanding to have an informed view on the subject so I'm just confused.

Thanks for the offer of the 20mm reamer. There seems to be a significant debate in the steam community about whether cylinders should be reamed or bored. I eventually guessed that I should go for boring rather than reaming but that decision was the result of guesswork rather than informed consideration.

Will

Hi Clive,

Sorry I've been a bit quiet for a few days.

The lump of brass a friend gave me is 30mm diameter so after a bit of thought and discussion guessed at a 20mm diameter bore with a 30mm stroke. I think I can visualise the tool I need to buy but I'm just a little uncertain about the exact part number. I'll maybe look up some possible part numbers and post them before I buy.

The glass sounds an interresting way to help reduce the hornet problem. Hopefully they won't come to the UK though.

I used to think that rouge only worked on soft metals but over the last few days I've learned otherwise.

Hansrudolf very kindly showed me his workshop and took a lot of time explaining an enormous amount.

One thing I forgot to ask: If a metric thread is used for medels is a coarse or a fine metric thread usually used?

Will

Edited By Will Robertson on 04/09/2012 21:14:06

Hi Clive,

What did you think of my proposed choice of tools? Let me know if I've got everything right and correctly understood your advice on the Chrome boring (oops - "internal turning" tools. Also let me know if my guess re. endmills is right - I've never had access to a milling machine before so I'm guessing.

I'm not enjoying this choosing-of-tools-and-stock very much - it's too much like work! - but I know that I have to get it right before I can start the enjoyable part. Thank you very much for all your help and advice.

Knee has healed enough for me to walk with one crutch and walk short distances without crutches so I reckoned that it was safe for me to set foot in a machine shop again. (I reckoned that trying to hobble about a busy machine shop on crutches would have affected the safety of others.) I faced off that random lump of scrap brass and it turns beautifully - very confident that I can turn it to high precision and a good surface finish

Hi Hansrudolf

Thank you very much for the link. It's really good to know that there's a company like this nearby, I'll visit them as soon as I can.

Will

Hi Clive,

Worried to hear about the proximity of the hornets. How destructive are they to the bees?

Now that the metal stock is decided on I reckoned I'd start on the tooling. Please let me know if I've got anything wrong:

For milling the valve faces of the slide valve of the S50 and other general milling I reckoned a handful of HSS end mills **LINK** rather than the carbide end mills (10 times more expensive) **LINK**

For milling the block of scrap cast iron for the base plate will the HSS endmills be tough enough or should I fork out the extra cash for carbide? (Guessing that carbide endmills may be difficult to sharpen without a specialist stone.)

I'll just hold the endmills in the existing ER collets and collet chuck on the milling machine - that should easily be strong enough for light cuts (correct me if I'm wrong about any of this...).

I think there are enough parallels, mounting bolts, etc for the milling machine.

For boring Reboring tool IFANGER ASB Standard, cobalt **LINK** (let me know if this is appropriate or not - I may have misunderstood your recommendation)

Will

Hi Jason,

Thank you very much - that's exactly what I'm after.

Hi Michael,

Thank you very much as well. That is a very good point. I'll think it over in detail.

I know I must come across as someone who hates imperial. I've got a collection of farm engines (Lister D Type, Stuart Turner, Petter) which are all imperial and I love them to bits but I come from the metric generation so it's more intuitive for me for anything small and precise. Metric also keeps the number of taps and dies to a minimum (I can borrow more exotic ones when needed).

Will

Hi Clive and Alan,

I tried Reves but their pipe unions seem to be all imperial. After a bit of searching, metric pipe unions do seem to be available from http://www.dampfmodellbau-keifler.de/

I think you're maybe right re. the pipe threads. I don't mind the steam pipes being imperial but I'm trying to avoid taping imperial threads anywhere on the engine. Maybe I'm using the wrong approach?

Not many dragonfly here compared to last summer.

Will

One part I forgot to mention. To get the steam into the valve block I was planning to simply thread a hole in the valve block then connect the piping using a Single Pipe Union (or similar). Seemed really simple, easy and flexible. Unfortunately I'm having problems finding metric Single Pipe Unions in model sises (imperial are easy but not metric). Does anyone have any suggestions?

Edited By Will Robertson on 26/08/2012 22:39:40

Hi Hansrudolf,

>but Search.ch knows you nonetheless

I suppose since they've put my telephone number online I should get a telephone...

It's been interesting living next door to these two legendary mechanical geniuses - and helping out on tasks that need an extra pair of hands. Come over and visit any time. Everything (garage, house, et all) is due to be demolished next year to build concrete flats. (I think the plan is to gradually demolish the entire canton and cover it in concrete.)

Hi Clive,

Many thanks - I'll get some WD40 and use that - nice and simple. (You're right - all those sticky long chain molecules in the semi-synthetic do make a bit of a mess.)

The Cobalt tools seem a world away from HSS

Will

Hi Clive,

So for the cobalt tools am I right in thinking just a stroke on the fine diamond stone to shapen (no need for oil or water stones). (These seem like high quality tools so I want to be sure that I know exactly how to care for them - I hate seeing tools being attacked by people who are ignorant of how to use them - **LINK** .)

Yes - the 10w30 is part-synthetic. Based on your advice I'll use it. 200 litre drum next door so no shortage of it

Should I try to use this oil as cutting oil or should I look for something more appropriate?

Thank you very much for the information about the piston and piston rod - I'll bear that in mind as I plan mine.

Very interesting to hear more about the bees. I'd never thought about how plants time their flowering in that way.

Today 150 years of steam navigation on Waldstattensee were celebrated with an illumination of the fleet. I can try to upload some (very badly made) videos if anyone is interested. It's amazing to see 150 year old steam engines still in daily use - especially given that most mechanisms made now are designed to disintegrate irreparably after a year or two at substantial environmental and financial cost.

Will

Hi Clive,

Congratulations on the honey and the health of the hives - a great outcome in such a poor summer!

You mentioned that you sharpened your Cobalt boring tools using diamond stones. After sharpening, do you finish honing the edge using the fine diamond stone or using an oil stone or water stone?

What were your thoughts about lubricating oil for a model engine? Can I use the 10w-30 I use for my turbo diesel or is another oil more appropriate?

Hi Michael,

Thanks for the link to United Cast Bar Limited - interrestign to find out more about cast iron. A lot I wasn't aware of.

Hi Hansrudolf,

I live at the North end of canton Schwytz - near kussnacht am Rigi and Luzern. I'm new to buying stock - when I was younger I just grabbed a lump of the right sort of metal from a box in the corner of the workshop - if it wasn't there I went to be grumbled at by the storeman and maybe get a lump of something which was hopefully suitable thrown at me. I never had to know how to specify exactly which alloy or where to buy it from.

Will

Hi Neil,

Thank you very much. That definitely sounds like what I'm after. Am I right in thinking that Meehanite Spheroidal would translate to "Sphärogußrundstangen GGG 60 Stranggegosen, Gußeisen mit Kugelgraphit" not "Graugußrundstangen GG 25 Gußeisen mit Lamellengraphit, geschält"? I really struggle to understand the German descriptions of metals.

One component I forgot - the lubricating oil. Can I use the 10w-30 part synthetic engine oil I use for my turbo diesel or would another oil be more appropriate?

Will

Hi Hansrudolf,

>So you are somewhere in Switzerland, buying from Mr. Burkhard?

I think so - I get the impression that he supplies the kind of metal stock I'm after and that he doesn't mind handling relaitvely low-value orders. I've still got a lot to learn though. Thanks for the advice about avoiding St37.

Hi Neil and Clive,

Great to hear you've got some good weather. The weather has improved here as well, 27 degrees all night last night. In Scotland I reckoned that it was impossible to sleep above 20 degrees but the Alps forced me to change my views on that. I remember my great uncle's equipment for spinning honey - miss that a lot.

Thanks for the advice about surface finish - I'll give a lot of attention to that - I think it will take me a few attempts to get it right - any suggestions?

It sounds like a lot of work sorting out the wrongly united hives - hope the owner does leave them alone now - some people have a terrible urge to interfere with nature until they mess it up.

I might have a try with silicone hose for dairy systems - fairly resilient stuff to withstand sterilisation by hot water and aggressive chemicals - small diameters were used for the vacuum lines.

Will

Hi Clive and Neil,

Thank you very much. I don't fully understand Mehanite Spheroidal (Sphärogußrundstangen Kugelgraphit I think) - does this referr to the way the iron is cast and the resulting crystal structure of the graphite?

Will reply properly ASAP.

Will

Hi Clive and Michael,

I rattled through some equations and the result came out that the smaller a boiler is, the more important it is to insulate it. I'll try to post them on here so that you can check for errors in my working (not sure the best way to typeset equations in HTML). Lentz put a lot of insulation round the cylinders of his engines but I know nothing about boilers so I'm only guessing that they would have been well insulated as well. The heat loss from an uninsulated metal vessel filled with water is substantial - great for domestic central heating systems but a problem when trying to keep metal vessels filled with water or steam hot (I found this out the hard way on dairy equipment but a little insulation made an enormous difference).

What did you think of the choices I had to make re. what stock to buy to repair the Stuart S50 and build my own engine? I'm particularly confused by the different sorts of cast iron.

Hi Clive (any anyone else who's watching this thread),

Here's my first attempt to specify what metals to use for the bore, piston, etc. I'm probably wrong in several places so please correct me:

Metals bought locally from www.ateliermb.com to avoid high shipping costs from the UK.

First I need to rebuild the mangled-remains-of-a-Suart-S50 I bought on Ebay - a new piston will be needed so I'll try this brass

Messingrundstangen Ms 58 Bohr- und Drehqualität, Festigkeit: F45 - 50, sehr gut zerpanbar
Which I think means:
Brass Ms 58 Drilling and machining quality, strength: F45 - 50, very good machining properties

(I'm guessing that it's right to use brass rather than bronze in a cast iron bore? The oroginal Stuart parts list said brass.)

I'll make a new eccentric strap from the same stock (going to have to hunt for a tap for the BA threads Stewart use).

All the gaskets and gland packing mentioned in the Stuart parts list are missing - I'll phone Stuart and ask for replacements. (The poor engine is in a terrible mess - it looks like an encyclopaedia of bad machine technique.)

The eccentric like it may have to be re-made - for this and for the valve spools of my own engine a steel with good machining properties - I think I've 3 choices:

Edelstahlrundstangen 1.4305 Blankgezogen, Automatenqualität, Festigkeit: 60, gut zerspanbar
1.4305 stainless steel round bars Drawn Blank, machine quality, strength: 60, good machinability

Stahlrundstangen 9SMn 28 K Blankgezogen, Automatenstahl, (teilweise auch 9SMnPb 28K), sehr gut zerspanbar
Steel rods 9SMn 28 K Drawn Blank, mild steel, (partially 9SMnPb 28K), very good machining properties

Stahlrundstangen St 37k Blankgezogen, Festigkeit: F40 - 45, gut zerspanbar, gut schweißbar
Steel rods St 37k Drawn Blank, strength: F40 - 45, good machinability, good weldability

Which one should I go for? The second one would maybe make my life easiest (a nice free-cutting leaded steel) but first might give best corrosion resistance.

Now for my own engine:

For the piston:

Graugußrundstangen GG 25 Gußeisen mit Lamellengraphit, geschält
Cast iron rods GG 25 cast iron with lamellar graphite, peeled

Sphärogußrundstangen GGG 60 Stranggegosen, Gußeisen mit Kugelgraphit
GGG 60 ductile iron rods contunuously case, ductile iron

Not sure which of the above I should use.

Cylinder: Random lump of scrap brass supplied by a friend.

For the base plate a cast iron cooking plate from scrap catering equipment - hacked into shape with a circular saw then milling machine to tidy the edges.

Flywheel: bought as casting.

All other parts from the metals listed above if precision is required, otherwise from random scrap.

Can you suggest flexible piping that's safe for use with steam while I experiment with different valve designs, etc.?
(I want to experiment a little with rotating valves (similar to Corliss valves) and piston valves before deciding what type of valve to use.)

Will

Hi Michael and Clive,

Thank you very much for such a detailed explanation. I think Corliss would definitely have agreed with you - he tried to keep the volume between valve and cylinder to a minimum. (He also had separate passageways for incoming and outgoing steam to minimise heat transfer from hot incoming to cooler outgoing steam). I think André Chapelon also put emphasis on the design of the steam passages.

Lentz certainly seemed to feel that cladding the cylinder was important - photographs of Lentz Paxman engines show thick insulation round the cylinder

**LINK**

Will

Hi Clive and NJH,

Thanks for the information about and photo of the hawk Moth - it must be too cold for them in the Northern half of Scotland. Did some background reading and interesting that some types of hawk moth pollinate orchids - interesting that such a beautiful pollinator works with such beautiful plants. (I've a collection of less specialised orchids - just simple Phalenopsis but still beautiful.)

Hope the Bees' move goes well.

I was thinking about bringing the steam in via the cylinder heads so that clearance coul.d be minimised - I was trying to work out how it would affect performance - theoretically I think it should give an improvement.

Cardboard prototype is probably a good idea to make sure that everything fits together.

Will

Hi Clive,

Good to hear that the bees are doing well with the better weather.

We have wonderful creatures in France and Switzerland that oscillate their wings like a bees but look more like a giant moth. They don't land on flowers but hover in front of them to suck the nectar out - like a miniature humming bird. Probably very different from bees in their lifecycle but amazingly beautiful so I thought they merited a mention. Wish they lived in Scotland.

I hate paperwork so I'll try to get enough stock that I don't have to order again soon. I'm also expecting to have to make two or three attempts at many of the components (more for some) as I refine design and technique. Then there's the next engine to think about...

The diamond stones will go on my first order to Arc Eurotrade

One odd question came into my mind. How close should the piston come to the end of the cylinder? Trying to work it out from first principles I reckoned that the piston should come as close as possible to the ends of the cylinder but many designs seem to leave a fairly large clearance.

How should I work out the sise of flywheel to use? I vaguely remember the calculus to work out the moment of inertia of a a flywheel but I've no idea how to relate this to a steam engine so I thought I'd guess the sise of flywheel based on roughly the the relative sises of flywheels and cylinders used in horizontal mill engines.

Will