Stuart victoria

[Former MemberParticipant @formermember12892]

[This posting has been removed]

[Howard LewisParticipant @howardlewis46836]

Ignoring, for the moment, the various Design Changes to components, and working from basics..

ASSUMING that the cylinder centreline is the same height from the bedplate as the Crankshaft centreline, the piston stroke will be twice the throw of the crankshaft ( [Crankpin center to Crankshaft centre] x 2 )

To allow the engine to rotate, the distance between the standards for the Slide Bars must be greater than the Stroke. This difference will be twice the design clearance between Crosshead and Slide Bar standards.

The Con Rod Centres should be Crank Pin Centre to Gudgeon Pin centre, with the Cross Head clear of the Slide bar Standards by the designed Crosshead to Standard clearance, at Inner and Outer Dead Centres.

The Piston Rod length should be such that at Inner or Outer Dead Centre, the Centre of the Gudgeon Pin bore just provides the clearance at each end of the cylinder.

Some designs might attempt to cater for the difference in effective Piston area, on each side, by allowing more clearance on the Piston Head side than on the Rod side. The rights and wrongs of this approach should not enter into this discussion, unless the basic design dimensions suggests that this is the case here.

Far easier, (but theoretically wrong, perhaps ), to aim for equal clearance at both ends.

Having taken some dimensions, it should be possible to find the dimensions for Con Rod Centres, and Piston Rod length, for THAT particular engine, which may differ from the dimension shown on a drawing, especially if the drawings are at different Design Change levels.

HTH

Howard

[Ramon WilsonParticipant @ramonwilson3]

Posted by Howard Lewis on 08/02/2021 16:05:10:

Ignoring, for the moment, the various Design Changes to components, and working from basics……

…. Having taken some dimensions, it should be possible to find the dimensions for Con Rod Centres, and Piston Rod length, for THAT particular engine, which may differ from the dimension shown on a drawing, especially if the drawings are at different Design Change levels.

Well I never Howard – who would have thought it could be so fundamentally straight forward

Sorry Howard – could stop myself

Best regards – Ramon (Tug)

[Howard LewisParticipant @howardlewis46836]

Well Tug,

There has been a lot of toing and froing about the dimensions on drawings, which seem to take little account of what mixture of parts are actually in THIS particular engine.

The lack of errata for the drawings (ie documenting Design Changes ) is NO help, and may well account for the problems.

I have seen a LOT of Design Changes and keeping all the parts compatible can be quite daunting.

I have come across some right hybrids; Bolts with A/F heads and Whitworth threads was one, liable to result in damage to one or other of the mating parts.

An engine that failed despite everything being correct to drawing; until it was pointed out that two parts of an assembly have moved relative to each other!.

Hence my suggestion to start measuring to find out what dimensions the parts should be.

The problem really seems to be to arrive at a set of components that actually allow THIS particular engine to function.

If all else fails, go back to first principles. Fine tuning can vastly improve function

Howard

[Former MemberParticipant @formermember12892]

[This posting has been removed]

[JasonBModerator @jasonb]

Howard. I think Ramon's comment was based on the fact we have been saying to make the piston rod and conrod length to suit what has been built for the last 3 pages of this thread.

The discussion of drawing is to try and see where the error may have come from in the first place so that others can avoid the same problem..

Even with the correction sheets I have found errors that they don't seem to cover, anyone able to make this to the sizes shown?

Edited By JasonB on 09/02/2021 18:38:01

[Howard LewisParticipant @howardlewis46836]

Jason,

Coming from a high volume manufacturing background, it saddens me that there seem to be so many comments about inaccuracies in model engineering drawings (Almost as many as my typos )

No wonder that so many models, supposedly made to the same plans, differ, apart from the modeller putting his or her particular shine upon it as well.

I can understand someone not familiar with caucasian numerals confusing a badly written 0 for a 6 or vice versa (Am sure that accounts for some of the errors in the chart that came with my HV6 )

Howard

[JasonBModerator @jasonb]

So far it's the only error that has jumped out at me having started to draw up the parts from the more recent drawings though I have yet to assemble it on screen.

 

Biggest problem will be deciding do I make it with parts as per Stuarts, make small alterations for what I would prefer to see or do a lot more extensive reworking. Either way I think I will stick with imperial as most builders buying a kit will be loath to put all the stock and fixings into the come in handy box. If Stuarts were able to offer a "castings only" it then that would be a different matter. I must say although I'm happy to work in both trying to sort these drawings out with all there fractions would have ben a lot easier if it were metric as it's easier to do a lot of it in your head.

Maybe a metric version will be the reserve of the fabricate and cut from solid brigade

Edited By JasonB on 09/02/2021 19:41:29

[Former MemberParticipant @formermember12892]

[This posting has been removed]

[Andy_CParticipant @andy_c]

Jason, the size shown on my set of drawings is very clear and reads 1 9/32 and 1 9/16 respectively referring to your highlighted dimensions.

[Former MemberParticipant @formermember12892]

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[David CauntParticipant @davidcaunt67674]

Jason,

The 1/32" would hardly take the 7BA clearance holes. Not looking for anything else.

Dave.

[Ramon WilsonParticipant @ramonwilson3]

Hello Howard,

Yes Jason is right – that was very tongue in cheek and irresistable I'm afraid but no offence was meant I assure you.

From the outset I saw this as fixable as is without recourse to sorting out the errors in the drawings.

I do agree though, and it has not been only my thoughts on the matter over the years, that the drawings we find ourselves with are at time less than favourable to say the least. Possibly an acceptable irritation for those with the skill and knowledge to see the errors but many have been caught by mistakes – but, 'tis a true old saying if you haven't made a mistake you haven't made anything and drawings do have mistakes despite the best will of the designer at times.

The finest drawings I have worked to from a ME point of view were those provided for the Lang Bridge engine by Helix Engineering – absolutely faultless. I won't comment on the most frustrating but theres certainly been a few to fit that bill.

Hopefully Arthur will get his Victoria running which is to me the main aim – irrespective of dimensional accuracy – which for me is far more important than knowing that everything is as designed to the 'n'th degree.

I think we are all singing from the same hymn sheet on Arthur's behalf for that.

Regards – Ramon (Tug)

[JasonBModerator @jasonb]

Andy, Br, David. The valve chest cover drawing is correct on the older version being 1 9/32" rather than 1 19/32" which allows the holes to be drilled within the plate rather than outside it!

[JasonBModerator @jasonb]

Well thanks to a very generous forum member I have been able to get my grubby little mitts on a set of Victoria castings and model it in 3D using Alibre. I'll post a few dimensioned drawings of the base, conrod and piston rod assembly in the next few days as that is what this thread is concerned with then post some more once the new forum software is up and running. here is a little of what's to come.

[JasonBModerator @jasonb]

Well I decided to prove my drawings before posting and as the Change in software is imminent will probably hold off until then.

Looking at the dates on my photos I first started on the main bed casting on 26th of Feb and today had enough done to see if the engine ran. There was some work already done but I have reworked quite a bit and also had to make a few missing bits from scratch so probably a similar amount of work to starting with a virgin kit.

In the video it is just running as a quick trial so no rings, gland packing or gaskets and the outrigger bearing is not held down so it starts to move about a bit at speed and knock but who wants to run them like that anyway when a slow tickover is as nice to watch as any clock or pendulum.

[Ron LadenParticipant @ronladen17547]

Lovely Jason and I agree much nicer at tickover something very satisfying about it.

Ron

[JasonBModerator @jasonb]

Thanks Ron

[Roderick JenkinsParticipant @roderickjenkins93242]

Sweet

Rod

[mechman48Participant @mechman48]

I like it, smooth running.. not the Jamaican bob sleigh team… or was that 'cool running'?..

George.

[Ron LadenParticipant @ronladen17547]

Jason, would it be considered as a long stroke engine it seems to have a fair length of stroke and the cylinder looks a decent length to, just wondered.

Ron

[JasonBModerator @jasonb]

The majority of "mill" engines were quite slow running and always tend to have a long stroke in relation to the bore, in this case it's double with a 2" stroke and 1" bore. The one that is just about to start being serialised in ME is 46mm stroke x 24mm bore so again similar long stroke.

The higher revving engines would tend to be very close or even square with equal bore and stroke

[JasonBModerator @jasonb]

Well I had a change of plan on the colour as the cream I had thought of using is no longer available so found a tin of something suitable in the back of a draw and sprayed that on then stuck it on a base.

The eagle eyed will see that I have added a bit of extra detail to the cylinder and valve chest as well as getting rid of the bolt together eccentric rod, apart from that it's fairly stock except for the corrected dimensions which will hopefully follow soon.

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