My Best Christmas Present!

[Alan Worland 1Participant @alanworland1]

Way, way back in the late 70.s at a Model Engineer Exhibition (Wembly Conference Centre) I bought a set of castings for the Stuart Turner No 4 Engine with the reversing gear. It was all tucked away in the loft ‘for later’

I knew where it all was for years, but just didn’t have the time to start it – something else always came along – you know how it is!

Then 3 or 4 years ago a big loft clearout (read move around to house a new central heating boiler meant that my engine got ‘repositioned’ and I have never seen it since. The loft is pretty full of all ‘usefull’ stuff and I have spent a good deal of time looking for it over the last couple of years.

Anyway, today, we found it! Well my wife claims she found it!

Fantastic! The parts are still in their vacuum packed box with both drawings and parts lists.

Best Christmas I have had for a long time!

[Alan Worland 1Participant @alanworland1]

[Sub MandrelParticipant @submandrel]

Well? Have you started it yet?

 

Neil

[Alan Worland 1Participant @alanworland1]

Yes! I started with the box bed, tidied up the casting then took a skim off the base, then using the base as a datum I trued the top face to the base. I did this on a faceplate on the lathe (ML7) There is no dimension for the height of this part so I just took enough off to true it up.

I started off using a HSS bit which was not up to the job so I changed to a tipped tool which cut nicely. I don’t know what grade of tip it was, I just have a few tipped tools which I save for these sort of occasions.

My first question! I fettled the casting but have not removed enough material to obtain a ‘perfectly flat’ finish – do I continue with the files etc or give the low areas a skim of filler or build it up with a high solids primer?

Which would be the right way of proceeding?

[DoddyParticipant @doddy]

I found that the base plate of my Stuart Score was flat before machining. Took a 5thou skim, turn it over to skim the other face and found it had a 10thou twist! Not sure if it was due to “over clamping” or it stress relief ? So reclamped and took several lightcuts – as you say there’s no height measure, just don’t make the top section too thin!

[John OlsenParticipant @johnolsen79199]

That twist is not too unusual, and is why people talk about seasoning castings. As the molten metal cools, it sets up stresses in the body of the metal, depending on the local rate of cooling. So when you machine off the top layer, it changes the internal forces within the metal and it moves.  If it seriously mattered, you would take a first light skim to take the surface off, then let it sit for a year or two. If you are in more of a hurry, a bit of temperature cylcling will do the job faster.

 

Quite often with Stuart castings you will find they are pretty much at the nominal size before you even take a light skim. This does not tend to matter, so long as you adjust any other parts that might be affected by a minor change in size. Of course, most of the Stuart  castings I have worked with are likely to be from many years back, so current production may or may not be more generous with machining allowances. They do tend to be good quality material.

 

regards

John

[TerrydParticipant @terryd72465]

Hi Alan,

 

I have had almost exactly the same experience as yourself.  I bought a set of Stuart castings in the late 70’s and ‘stored’ it awaiting the chance to work on it.  When I divorced and moved, I carefully packed it and ‘stored’ it again, and repeated again at the following house move (18 years ago now) carefully storing it where I could find it.  However a loft reorganisation two or three years ago meant that I can not now find the damn thing. Your story gives me hope.

 

I bought another set at the Ally Pally last year, but then my workshop burnt down.  I think that I will be haunted by Stuart castings for the rest of my natural.

 

Regards,

 

Terry

[Alan Worland 1Participant @alanworland1]

I must say I have found the castings machine and file well. I have removed ‘spurs’ and try to make one surface flat enough to clamp to try and not introduce distorsion when clamping to machinie my first face.

Perhaps they machine ok because they have been hot/cold in the loft for 30 years? Don’t suppose that is really hot enough though.

Sorry to hear about the workshop Terry, are you out of action at the moment then?

If it’s any help – my castings were over the back between the water tank and the chimney!!!

 

Alan

[John OlsenParticipant @johnolsen79199]

They say that Gyms make their profit on the people who join up and then never find the time to go, and I suspect that Stuart Turner likewise make their profit on the people who buy castings and then never get around to machining them up. I have done quite well with partial sets from club auctions, I got a Double 10 and a Number 1 for $15 NZ at one auction, they both had lots of bits missing but ther was enough to work with. I also got the base of a triple for $1, and have machined the rest from solid. That one is about 80% done now.

 

I also got given a Henry Greenly Uniflow engine set of castings that had been sitting unsold in a model shop since the 50s. By the time they gave them to me they had been on the shelf over thirty years. The original blueprint drawing is dated 1922, the castings were by the Jackson-Rigby company. That has made up into a nice little engine, I suppose I should paint it!

 

The time in the loft will certainly have helped. It doesn’t need a big range of temperature change, although the stress releiving will happen faster if it is big. So long as you don’t raise and lower  the temperature so fast as to introduce new stresses!

 

regards

John

[Ramon WilsonParticipant @ramonwilson3]

Hi Alan

How are you – good to see you are into another project.

 

If I read your comment correctly are you actually refering to the cast surfaces that need smoothing prior to painting rather than those you have machined?

 

If so take the worst off with a file then degease it and lay an epoxy based filler into the pores –  a product called JB Weld which is readilly avaliable is excellent for this. It takes

much longer to cure than say P38 filler but is ready for filing – you can even machine it – after leaving overnight. It’s capable of standing up to quite high temperatures, very resilient and is oil proof – paint over with grey primer after its been smoothed (but leave that until after you have most of the engine assembled ie strip it down for painting) as the primer will absorb oil as you go. If you find it a little runny a drop of talc mixed in will improve things without any detrimental effect as a filler

 

Regarding twisting of bedplates and similar parts – even if of fairly substantial size. You are obviously aware of the problem of distortion but this more likely to be the culprit than locked in stresses I f feel. Cast iron is normally quite dead in comparison to say bright mild steel and locked in stresses are not  usually as evident. It’s quite surprising how little it has to be out for the clamping to sometimes enhance it.

 

Careful packing under any low spots on the intial clamping surface followed by a light cut just sufficient to clean up should produce a flat surface which can then be used as a reference face to get the other finished. Reverse and bring the first face to final size. An extra op but one which allows stress and/or distortion to be slowy dissapated.

 

Basic stress relieving of CI would require a fairly high temperature – much higher than you’d find in a loft I suspect – and slow cooling. Annealing of any hard spots would require the whole casting to be taken to a red heat, held for a few mins and similarly very slow cooling.

 

My previous experience with Stuart castings has been without problems and have found them a joy to machine but they were from when ST was at Henley – what the new ones are like I have no idea the ony thing I find irritating is those cast in steam passages – they can be a real pain.

 

Good luck with your engine Alan

 

Regards – Ramon

[TerrydParticipant @terryd72465]

Hi Ramon,

 

You mention JB Weld as a filler. have you tried Milliput?  It is used a lot by railway and military modellers etc.  It is an epoxy based putty type filler which has all the properties you mention but has a putty like  consistency and can be used with water to smooth and thin it for use when kneading.  A little goes a very long way and is available in several grades from model and handicraft shops in small handy amounts.  I have used one pack over the last 4 years, a little goes a long way! It’s worth a try.  It is also great for modelling small items and accessories for dioramas.

 

Best regards

 

Terry

[Nicholas FarrParticipant @nicholasfarr14254]

Hi, I always understood that cast iron castings were left out in the elements for a year or so before machining,  like John has said to season, and to releave all the casting stresses. Is there any truth in this, or is it just a myth?

 

Regards Nick.

[Ramon WilsonParticipant @ramonwilson3]

Hi Terry,

 

Yes I’ve used Milliput for years now certainly since the late seventies – mainly back then in plastic modelling. I still use it too as it does have good properties as you rightly say but personally, for this application, I would prefer to use JB Weld. It is a very strong product, much finer grain than Milli I would say though a little thinner. It’s big virtue is the higher temperature rating. I have a table engine progressing slowly (far too slowly)  – all from solid with the casting effect gained by JB Weld. JB can be laid into the surface with a pallet knife so easilly. Tougher to sand -oops emery – than Milli but it doesnt clog files near half as much.

 

There are lots of varying but similar ‘epoxy based’ products available – ‘Duro Putty’ for one – this can be rolled out to 3-5 thou thick and once cured is totally flexible unlike Milli (and probably JB) which goes brittle quite quickly once cured.

 

Milliput comes in three grades I believe – the white ‘superfine’ is not a patch on the original

 

 I’ve just noticed the time – I’m off

 

Regards – Ramon

 

 

Edited By Ramon Wilson on 12/01/2011 00:11:56

[DustyParticipant @dusty]

Hi Nick

      No it is not a myth. I can remember visiting relatives in Ipswich in the 60’s, travelling by train. Just outside Colchester was the Colchester lathe company. Between the railway and the factory were row upon row of lathe bed castings. They had been there for some time as they were all red rusty. I mentioned this to my boss at the time, an engineer of some repute, he told me that they left them like that for about 18months after they had had a light skim on a couple of faces.

[Nicholas FarrParticipant @nicholasfarr14254]

Hi Dusty, I didn’t think it was, as I seem to recall my farther telling me once many many moons ago, that when he worked for Cooper Roller Bearings, thats what they used to do with thier cast housings. Don’t know if they still do.

 

Regards Nick.

[Alan Worland 1Participant @alanworland1]

Hi Ramon,

Thanks for your input – very quiet on the work front so rather than waste my time (as if) I though I would get on with something constructive! Your keeping busy I see judging by your posts!

Your correct it is the cast surfaces I was referring to, I have put various files over them but there are still surface imperfections, nothing major but they would take a good deal of more filing to remove so JB Weld sounds worth a go (would this be used to smooth large machine castings as well?)

I have been taking a ‘cleanup  cut first as you suggest after finding the most true surface – seems ok so far

John my castings have been hot and cold in the loft for the last 30 years and guess they could be better aged, but they machine a treat!

[TerrydParticipant @terryd72465]

Hi Ramon,

 

I’ve always used Milliput ‘original’ (I also think it is best) previously as it is an epoxy and can be used with water to help manipulation, I’ve not used JB Weld but note that they claim that one tube contains hardener and the other contains ‘liquid steel’ and epoxy resin.  What do they mean by ‘liquid steel’?  Does it mix like normal epoxy adhesives and is it runny like Araldite or have a putty like consistency like Milliput and can it be used with water?  I note that JB has a temperature resistance of 260 deg. C as opposed to Milliput’s 130 deg C so I might give it a try.  Sorry for so many questions but I am quite interested in trying the product.

 

Hi Alan, 

 

I’m not sure about other manufacturers but Boxford used to use ordinary cellulose knifing putty for dressing their castings (I suspect ordinary auto stuff from the discussions I’ve had with the older employees of Boxford) .

 

Regards

 

Terry

Edited By Terryd on 12/01/2011 22:30:58

Edited By Terryd on 12/01/2011 22:49:10

[Alan Worland 1Participant @alanworland1]

I must admit JB Weld sounds good, I think it must be an araldite type product with solids for ‘body’

I think when I got my Myford, before I refurbished it, where the paint was chipped there was quite a depth to the chip which appeared to have a whiteish undercoat/primer/filler base to it.

[Ramon WilsonParticipant @ramonwilson3]

Hi Alan and Terry,

 

I came across JB weld in the early nineties I think. I was making silencers for my aerobatic models/engines when I read about it’s properties. All the silencer parts made prior were held by a long through bolt but after using JB Weld this was dispensed with the parts just held by the JBW alone. Glow motor exhausts get very hot but I never had a failure so it was very much a case of  ‘impressed satisfaction’ – I have sworn by it ever since.

 

The term ‘Liquid Steel’ refers more to the fact that this part of the product has a steel powder filler –  possibly it could be iron as its very black – it is certainly not ‘liquid’ however.

Quite a bit thicker than standard Araldite but not as ‘stodgy’ as Milli. Once mixed its quite thick but unlike Milliputs consistency will ‘slump’ slightly if in thick layers. It will fillet quite well in corners however. I have not tried water to aid shaping as you can with Milliput other than a wet finger so can’t really say. It does spread easily onto surfaces though and ‘feathers’ well. It has extremely good adhesion and will ceratinly fill and smooth cast surfaces.

Loctite ‘Metal Set’ is similar (quite a bit more expensive too) as well as Devcon ‘Plastic Steel. Both of these are excellent as well, very tenatious and tough once cured but are more similar to Miliput in consistency

It mixes just like all the others ie equal parts and can be handled in about 8 hours but is best left overnight / 24 hours for best results if working it after.

 

BTW when I said in my previous post about Milliput and JB Weld being brittle I was meaning if thinned out as described for the Duro Putty.

 

I know for some this will be ‘plastic’ and should have no place in engineering – well each to his own – I will give something a try if it works then so be it but if it doesn’t just forget about it ……

 

Hope this is of further help to you both.

 

Nicholas/Dusty – all the castings made on the shipyard where I began work were always left to ‘cure’ It was always said they were improved by peeing on them too but I don’t think many will want to do that with their nice new Stuart parts

 

Regards – Ramon

 

 

 

 

 

 

 

Edited By Ramon Wilson on 12/01/2011 23:35:28

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