Stuart victoria

Back in from the shed and I've looked a bit deeper, there are also differences in the bed, figures are conrod length followed by guide bar ctr to crank ctr

1976 drawing 6.25" and 6.156"

1993 Drawing 6 1/32" and 6 1/32"

Princess Roya; 6 5/32" and 6 5/32"

Only the last two will give equal travel 1" either side of the guides mid point, if positions have been tweaked to get the parts to sit nicely on the cast bosses then crank will need the same adjustments.

Hi

Thanks for your comments.

Will phone stuarts on Mon to verify the correct distance between centers

Regards

Hi Arthur - just come in from the shid and seen your PM. Some others may benefit from these thoughts

I would agree with others but looking at the images it's likely to be one of several things.

Not in any order specific order.

The piston rod is too long - cross head hits rear post before piston is at bottom of stroke

Con Rod is too short (likely) or Crank throw is too big but if the latter the slide should move the same distance in the opposite direction (unlikely)

Main bearing position is wrong relative to length of con rod.

Cross Head slide is wrongly positioned.

Looking at your images you do not appear to have anything positioned wrong and you say you have checked the dimensions. Given that all is correct in layout dimensions - you need to evaluate what is causing the problem.

Ignore for the moment any drawing dimension of parts.

Concentrate first on being able to get equal movement of piston and cross head.

With the piston at mid stroke so should the crosshead be. If you can set the piston and cross slide in such an equal set up then you have the piston rod the right length - ie equal movement either side of mid stroke gives an equal gap between piston and cover and between cross head and end post. If you can't obtain that equal movement then the piston rod requires to be modified to give that situation. Once that is correct the rod length can then be looked at. Bear in mind at mid stroke the crank will be at an angle relative to the perpendicular position.

Always happy to add more if required but if you begin with trying this first I think you will soon see where the error lies.

Regards - Tug

Arthur, did your drawings and the castings all come from Stuarts as one or have you bought drawings to complete an old casting set? The reason I ask is that from the photos your main bearing is overhanging the cast pad of the base front & back. The old drawings had a narrower bearing or at least the hole spacing is less no actual dims on the overall bearing size. So could it be you have a casting that needs the old drawings?

Jason has pointed out that there are 2 standards of drawing so presumably there are 2 standards of bedplate too. Perhaps Arthur has mismatched drawings and castings. If so and if bought new from Stuarts a replacement con rod would appear to be merited. Some practice at making con rods would also be included.

Jim

I don't think this is a question of 2 standards of drawing per se Jason as unless the design has fundamentally changed in conrod length or base length the error is far too great. That said 'stranger things 'ave 'appened at sea'

To my mind this is a more question of geometry due to an error in dimension. Looking at the images the slide is touching the upright at rear most stroke (BDC) and well short on the fore stroke (TDC). As that stands, as has been said, the con rod requires lengthening to create an equal gap at each end of the stroke. One still needs to know where the piston is relative to the slide however, so personally I would establish that fact first - from the model - then check the rod length and ammend or remake as required to give equal movent of crosshead from TDC to BDC.

Tug

Edited By Ramon Wilson on 06/02/2021 18:53:09

Ramon, Arthur has zero gap at one end and says there is 7/16" gap at the other, Could well be the 7/32" difference in conrod lengths shown on the two drawings. Increasing his rod length by 7/32" would put it in the middle and make it the same length as Bill's (br) which he says runs fine and is bang on ctr.

Edited By JasonB on 06/02/2021 19:04:36

Just looked back and see Arthur has the book on building the Victoria, any chance the drawings in the book may be different to the paper plan and some dimensions from each used?

Anyone got the book who could confirm conrod length?

Well that would make sense Jason but that's a huge difference between original and updated 'versions'. A change as big as that, unless a typo, could be considered a 'change of design'

As you say the book dimensions may be at fault and if Arthur is working to them then that could be where the fault lay.

I would still start at the mid point - the symmetry of that has to be correct whatever dimensional error is at fault. Working from that as a base point will quickly show where that error lies - If that proves the rod is wrong then a new rod it is

In the Victoria book the dimensions are as Jason quoted for the Princess Royal.

Thanks Gordon.

To further muddy the water the '76 and '93 drawings both have hole spacings for the cylinder mounting that don't tie in with the length between the holes in the feet, one puts the cylinder off ctr too being different each side of the cylinder ctr line!. Though it is possible they have made an allowance for thick gasket paper. As already mentioned bearing length and hole spacing is different too.

The only constant is the 3 3/16" for the guide posts so suggest the conrod length altered to give equal throw of the cross head either side of guide ctr .Then cylinder is moved to get piston movement equal checking piston rod length at the same time.

Maybe nothing but from the photos the main bearing is not centralised on the pad. Seem to remember the bearing casting was changed at some time. How about contacting Keith Appleton as he has You Tube series on building this engine?

Are we being a mite pedantic here Jason - thickness of a gasket paper. The offset seen in the images is considerable.

If the 3 3/16 is constant - and on Arthurs model - the slide isn't equal about the midstroke then I stand by my thought - set the slide central and ensure the piston is at mid stroke - shortening or lengthening the piston rod as neccessary and then deal with the con rod to suit. No need to move the cylinder at all unless you want to make this absolutely to print which at this point looks like two or more versions - one in conflict with the other.

To me the thing at the stage Arthur is at would be to accept the differences and make whats been done work. The thing to do is adjust the model to suit whats been machined - and that may mean making a new con rod

Theres been a degree of criticism of Stuart castings and drawings not matching at times which perhaps goes to show that the Stuart of today does not have the same volume of care that they did of old as when at Henley but that was a long time ago!

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Gordon yes that is one of the points I mentioned the two drawings have hole ctrs for mounting the bearings at different spacings one at 1 3/8" the other at 1 1/2" so could well be to suit different castings Or are they now an extrusion.

Ramon no pedantry. My comment was about the cylinder mounting dimensions also having anomolies, not enough to give the size of problem shown but will not help the situation. One drawing puts the cylinder central on the 10" engine ctrs (cylinder ctr to crank ctr) the other has it offset.

Combine these varying sizes with the distance between the piston rod end leg and the first post of the guide bars also being different by 1/8" and differen piston and piston rod dimensions between the two drawings (and maybe the book) then this too adds to the ambiguity of where the cylinder should go

Not totally sure what thickness Oakenstrong they supply but think it may be 1/64th so twice that will add a 1/32" to length of assembled cylinder, enough to make the holes not line up . But that's a consequence of them using the same cylinder casting on several engine sand having to fit the legs to the covers.

The beginner is more likely to build to drawings than "fit" the parts and as in this case only has problems as things are bolted together.

Edited By JasonB on 07/02/2021 10:42:39

Hi Jason

I guess then it remains to conclude then and not unreasonably, that Stuarts - as of now - have changed drawings and castings without giving due credit to that fact compared to old to new purchasers? The design has changed it should be clear to all.

We all know over the years that many drawings have mistakes in them - including my own - but the biggest 'crime' to my mind is when that mistake is allowed to perpetuate without alteration or at least an indication as to the anomalie.

Sometimes we have to accept the fact that we've made something wrong - either the wrong dimension firmly fixed in our heads - done that more than once!, sometimes it's because we read the drawing wrongly (definitely done that a time or two) or sometimes because the drawing is downright incorrect. It's the latter that is the most frustrating and particularly so to those early to machining who have just found that the part they have made is unfit for purpose and even more so to those of us who feel we 'should have seen it' but didn''t.

To have to make something over again is always a frustrating situation, especially if you think you are close to getting something ready to run. We are all different in our approach but we can - indeed should - learn from mistakes either by our own hand our that of others. Remaking a part is part of the process - annoying but a fact of machining life.

In this instance my view is to rectify what's wrong with the model as built - to me it doesn't look that far off so rather than focus on drawing dimensions which are conflicting and confusing it's to look at the situation and try to recover with as little input as possible. Getting the drawing dimensions 'correct' is for the next builder unless as already said it's Arthurs desire to get it absolutely correct to print - in which case which one and for which castings??

I well remember my early days with LBSC's Pansy 0-6-0. I took the frame drawing at face value and drilled all holes as called out. As other parts progressed it became apparent that all the brake hangar holes were incorrect. I borrowed a set of the relevant ME mags that covered it expecting to find an errata. Well it was there but only on the last paragraph of the last installment - something like " some may have found the brake hangar holes are in the wrong position but not to worry, just plug them and redrill in the correct place" I wouldn't mind betting those drawings still carry that mistake.

Arthur should do what he feels best - I know what I would be doing at this point

Regards - Ramon

Just watched Keith Appleton's video where he uses 6 5/32 inch centres for the con rod and says these dimensions are in an errata paper from Stuarts. Unfortunately he has not got to the assembly stage yet to check the fits.

No that throws another spanner in the works but does tie in with the book and Princess Royal and at least Stuarts have made the builder aware.

Until Arthur comes back to use with where he got the castings, drawings and book plus what response he gets from Stuarts it's all a bit up in the air.

I think both Conrod and piston will need to be remade, hopefully the piston rod may only need shortening though if it turns out the 6 5/32" is right then I think the piston rod will be too short

Well although he has blanked out the drawings it's possible to see that the errata sheets cover all the things I have been mentioning. Main Bearings, Bed plate, conrod, piston rod & piston

Edited By JasonB on 07/02/2021 12:31:09

This gets more confusing as there are 2 editions of the book on building the Victoria with different dimensions. Also my drawings from the kit I bought in early 1980s quote 6 5/32 in centres; the drawing is dated 13/4/76.

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