Another Stuart Major Beam Engine ( some comments and photos)

[Mcgyver]

I've always thought that Stuart M.B.E. was a particularly great looking model...and you've done a first class job on the build. 

I was looking the other day at the 1959 ME build, or rather it's a revisit of George Gentry's design published in the early twentieth century.  I believe that is loosely what the Stuart design follows?  Looking a bit further, I found compete 3d cad models for it on grabcad.  Amazing, people who's hobby it is to do 3d cad models have chosen some of these great old engines.   Project number 648 in the queue is to take some hunks of cast iron, a 3d model, a cnc machine and see if I can wittle one of these without castings

[Chipswitheverything]

Jo, having got some idea of your casting stock whilst looking back through ( some of !) your very many, and very interesting posts, I have no doubt at all that a set of these beam engine castings will be joining them....

  Mr Mcgyver, the Stuart Major does take some of its parentage from the old Geo. Gentry design, but by way of the Championship cup winning model that Mr H A Taylor made and exhibited at the Model Engineer exhibition circa 1967.
  H A Taylor did a useful illustrated write up of aspects of his engine build in two issues of Model Engineer magazine during 1968. ( Late June/ early July issues ). His beautiful award winning engine followed the Gentry design in many respects, but where some patterns had been lost, Mr Taylor redesigned the components to his own specification.
 Such patterns as survived had belonged to the SMEE, and they were sent to Stuart turner to be cast.   Some of the other components were made by constructing them from the solid, and a lot of free machining stainless steel was used.  So when Stuart decided to market the Major, they must have had to make up various patterns to supplement whatever was there from the original set.  H A Taylor made his connecting rod from an 18" length of stainless steel bar!, forging the "U" end, so Stuart has at least saved lesser mortals from that operation by producing a nice casting.

I've read that the 1959 write up and drawings for the 1" scale engine is full of dimensional mistakes, whether these were ever corrected in the marketed drawings, perhaps another member with experience of this 1" engine can tell us.

Yours, Dave

[JR72]

Hi David
What else would I expect? Great pictures model engineering at it`s very best, and to see it on your bench as I have done well it`s just awesome.
John

[derekwarner]

Dave....these tapers as shown, do they act in the same manner as a Morse taper ie., self locking with minimal engagement force and a similar light force for disengagement?...[7 - degrees comes to mind?]

From memory, in older  lathes, the Morse taper in the tailstock did actually deform after thousands of engagement impacts from the hardened sleeves and sometimes required a piece of cigarette paper to take up the  slack.....

So I would assume the same would not apply here as the tapers locking these engine components would not be an often disengaged part

Is the straightness, flatness & surface finish of the tapers still a required or attained constant in model engineering......are they blued & scraped as in full size similar applications in industry?

Derek

[Chipswitheverything]

"Is the straightness, flatness & surface finish of the tapers still a required or attained constant in model engineering......are they blued & scraped as in full size similar applications in industry?"

Hi Derek, I made the tapered cotters and gib pieces to the Stuart drawings and they lock very well on assembly. A tap with a little brass block will free them easily enough.
 These components are pretty small, only about an inch long for the cotter.  I doubt that I did more than draw file the edges by running them along a fine Swiss pillar file. On the real engines I can imagine that the fitting of a foot long by inch thick cotter and gib did involve blue and a careful process.
 The main difficulty with these parallel motion links over the (too ) many years of the Major build has been ensuring that all the separate bits are kept with the applicable link, and all taken apart and reassembled - on such occasions as have been needed - in the right orientation. The pieces are a bit too small to be able to mark effectively. As far as I can, I don't dismantle them at all!
 
John, thanks for your kind comment.    Cheers, Dave

[Mcgyver]

I've read that the 1959 write up and drawings for the 1" scale engine is full of dimensional mistakes, whether these were ever corrected in the marketed drawings, perhaps another member with experience of this 1" engine can tell us.

Hi Dave,

Thanks for the information.  On drawing errors, the 3D modelling should catch errors before the turn into parts.  As I mentioned there are a couple of models of the '59 engine on grabcad, free for the taking.  These let one inspect part by part how it comes together and spot inadvertent interferences.  It would be interested to connect with the cad modeller and hear his take on drawing errors -  at least one of them modeled from the '59 drawings. 

[Chipswitheverything]

Hi Guys,
While I should have been busy with the filling, priming and painting of some more beam engine bits, for some reason I have been mucking about with the Stuart steam hammer bits and pieces that I've mentioned before. I've only had them since 1979, so you can imagine the sense of urgency...

 Yesterday I did a "fer instance" bunging together of the bits of the thing, so that I could make a list of jobs still to attend to on the hammer. The list took up most of an A4 sheet, so there is a little way to go.  But though the hammer is just crudely chucked together with missing bolts, gaskets, and various bits skew-whiff, it was quite exciting to me to get a glimpse of its what may be its potential once it's all eventually sorted out.   ( Not to say, painted...!)  Treat these photos very much in the spirit of a work in progress.

Got the base casting set up on the mill again, for trimming the column plinth with a radiusing cutter, so better go and do that!

Cheers, Dave

[Chipswitheverything]

Just reviving if only slightly, this antiquated post of mine about the Stuart Major beam engine.  The dismantled engine is still in the filled and primed state. Ridiculous, but in the mean time some years have been mostly taken up with totally unrelated things necessary to deal with, and the Stuart steam hammer and the Quorn tool grinder have been much worked upon and now finished.
 I was lucky to see the very fine example of a Major Beam which won a Gold Medal at Sandown Exh. some years ago, and I was taken with the way the builder had designed the plinth , which let about a quarter of the flywheel down into a well, and made the main rather massive plinth for the bedplate lower.  Thought the proportions and general appearance were improved by the change.
 
The casting as supplied to support the outer crankshaft bearing is about 6" high, and it needed a cut and shut modification to about half height to appear like the one on the Sandown engine. There is not a lot of spare iron in the legs of the casting, so I did the drilling for 4BA capscrews and some 3/32" dowel pins in the mill to be sure of the positioning.
 The match of the cast struts with big sections cut out, and the faces milled off, was pretty good;  a spot of filing and rubbing down with primer will fair the bits in and hopefully not show at all .
 Not the most exciting update!, but I'm scheming out some ideas of how to make the base and looking for materials, the project might lurch back into life...  Dave