Myers Model engine works Murdoch single cylinder

[Jasonb]

I think one needs to bear in mind a few things.

Many of these kits are quite old and date from a time when the average hobby machinist had just a steel rule and firm leg calliper which was set from the rule to do their measuring with. Not much point in giving them tolerances to 1/10ths when all they can really go by is feel. I would not mind betting that Keeley originally built that to fractional sizes rather than to the many two decimal place dimensions shown on the drawing.

Even today what people have in their home shops varies. Again why give an internal bore to 1/10ths tolerance when all they may have is a digital calliper that is not going to be able to measure as well as an internal bore mic that many won't have. Same with external diameters, the digi calliper is a bit better on external but will only read to 0.0005". Not everyone has a set of 10ths reading micrometers, I only have external micrometers thet go upto 1" and no internal ones but I get on and make engines.

The engines are built by one person, no need for part A and part B to fit if made in separate workshops or for spare parts to fit in the future so the old art of "fitting" is used. Spotting through holes from one part to another was common so no need to detail the positions on more than one part. This is becoming less common with more workshops having mills and DROs

Many kits started as a personal project, possibly someone had a full size engine and took measurements off that to make a model for themselves, may have done some form of drawings or could just be scribbled notes and fag packet sketches. Later someone sees the model and wants to build one so asks for a set of castings. Original builder may try to do better drawings or may leave it to a third party to come up with somethng. I have had several kits which came to me as just castings and there were never any drawings and maybe only one or two other completed models. They have built up into good working engines but someone who has not built a model before would find it difficult. So some drawings however poor are better than none at all.

I mentioned a few posts back about costs. There is not much money to be made from supplying model kits. What would be the cost of producing a commercial quality set of drawings all fully toleranced, etc? A fully working model (from current castings) would need to be disassembled, measured, fits worked out and then drawings produced. What payback period should the supplier aim to get their costs back, spread it over the next 5 casting sets or the next 20 but that could take 10 years or more. Even then would that address things like shafts running in aluminium? However it would not hurt to hand amend master drawings if errors were reported or include an A4 or Letter size sheet listing errors.

[Chipswitheverything]

That seems like an excellent summary of the situation that may reveal itself when working on older designs of models : as you say, very many of the designs have been around for ages, and have been bounced around between different suppliers and different foundries .  Probably no one has been making much profit out of a lot of it as sales trickle in.

 A good many sets of castings and drawings never make it to completion, may just sit on a shelf under a bench for years, so feedback on problems could be patchy. An experienced worker will perhaps just spot a mistake or snag and get on with their own solution, thinking that most will do some similar work-around.  Or a builder may have their own limitations over and above snags with the drawings and supplied components, vide the rather sad ST triple that was rescued by Jo, where all sorts of things had gone wrong despite undoubted high hopes of the optimistic first builder. There could be a few more of these stories out there than one tends to think, kits of all varieties appear to have a very high tendency to not reach completion ... 

Looking through various model build series of articles in , say 1950's or sixties Model Engineer magazines , bears out entirely what Jason is saying about measurement and fitting, and limitations of the workshop equipment in most home 'shops of the time. A lot of the model engineers would have been familiar with fitting skills and hand work from their training back in the day.  Being able to use a "tenth" reading DRO in their wooden shed garden workshop would have left them slightly mind-blown!  Dave

[CI]

Until AutoCad and similar programs, the manual drawings were totally non-associated in every way.
With AutoCad, you could at least draw a shape to some given size, and then copy that to some mating equipment or feature, so associative in that if you got the dimensions correct on the first use of an item, and copied the item, the copies were also correct.

We kept the highlighter people in business for many years.
We would mark up a blueline print using red fine-tipped pens.
When the redline came back from the drafting person, we used a highlighter to check every line.
The drafting people often used their own colored highlighter, different from the color the engineers used.

The system we adopted was I think one used by the Navy, which as I recall was called the "Redi-Check program".
The redi-check system made logical comparisions across multiple disciplines, to find conflicts, errors, etc.
One started with a single discipline, and checked values, such as fuse and breaker sizes against wire sizes, conduit sizes, bus sized, equipment sizes, etc.
Then one overlayed other diciplines to find out if ductwork, piping, and various equipment clashed.
Again, lots of highlighting as one went through projects.
The Navy paid us to redi-check other people's projects, and it was very cost effective to have an unfamiliar set of eyes take an objective and unattached look at a project.  Change orders during construction are generally very expensive.

I have to guess the designer for Murdoch engine sketched things out with a marking pen, and the drafting person translated that to drawings.
What did not seem to happen is the highlighting process, where either the drafting person made errors that the designer did not catch, or the designer made errors, and did not self-error-check.
Sometimes one can get so familiar with one's own drawings that it can be difficult to spot errors; the forest all starts to look like a bunch of trees.
There is a methodical process you can use to check engine drawings though, using highlighters.
If the designer created engine designs on a casual basis, then he may not have been familiar with adhering to normal engineering rigors.

2D CAD can be helpful as mentioned above, but even then, the drawings will only be as good as the person designing/drawing/checking them.


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[55fairlane]

The engine will go on a brief holiday, a friend is going to try and clean up the drawings a bit....while this happens I am going to re design the upper breaking blocks....they aren't visually pleasing. 

Lots of things I still can do to the engine.  

I did finish up the one bearing pillar,  not sure I'm happy how it turned out, but I'm going have to live with it.

Pictures of finishing one side, I don't use my deapth mic often anymore.  Purchased a very nice brown and sharpe set in my apprenticeship....don't use them much anymore. 

Picture of the pillar sitting on the base, pictured with my 0-1, 1-2 & 2-3 mics for scale....

[55fairlane]

I think one needs to bear in mind a few things.

Many of these kits are quite old and date from a time when the average hobby machinist had just a steel rule and firm leg calliper which was set from the rule to do their measuring with. Not much point in giving them tolerances to 1/10ths when all they can really go by is feel. I would not mind betting that Keeley originally built that to fractional sizes rather than to the many two decimal place dimensions shown on the drawing.

Even today what people have in their home shops varies. Again why give an internal bore to 1/10ths tolerance when all they may have is a digital calliper that is not going to be able to measure as well as an internal bore mic that many won't have. Same with external diameters, the digi calliper is a bit better on external but will only read to 0.0005". Not everyone has a set of 10ths reading micrometers, I only have external micrometers thet go upto 1" and no internal ones but I get on and make engines.

These are both valid and interesting points.....and that makes much sense........however I will say this.....with many missing dimensions & combined dimensions not adding up to the mating part, it makes this a very difficult undertaking......as a professional machinist i guess I expect much higher standards

And just for you, I did a picture of my engine with my 0-1 , 1-2 & 2-3 mics......🤣 🤣 🤣 🤣

[Jasonb]

It must be nice to have those larger clamps mics Though they look mor elike 5-6" to me

Ah the bearing pedestals, they were one of the items that I felt were rather chunky. I think the castings could still be used if you wanted to do so. Just reduce the overall size so the foot is smaller and then step in again to further reduce the upper body. Easier if the protruding round bosses are done away with and preferably changed to flanged split bronze bushes but you could stick with the aluminium and use a rotary table or similar when reducing the thickness to leave a boss standing proud. Radius corner mill will leave a nice fillet for that cast look.

It is very likely that the model was inspired by the B Hick & Sons engine, if you click the image in this link it comes up a lot larger and you can see the much less bulky bearing pedestalls

https://www.gracesguide.co.uk/File:Im1851Cat287b.jpg

I would also make the smaller cylinder pivot bearing pedestal a bit nicer, a smaller version of the main one at the front.

[Jasonb]

Something like this looks more like the engraving. The green represents the top of the standard so you can see the "foot" has been reduced and also the further reduction of the main body. You could arch the top if you wanted to make it match the bearing ones but I have gone for similar to the engraving but put 4 external fixings rather than having to use the cap retaining studs right through.

Would need slight work to the crank arm and crank shaft so that the shaft can be located without moving axially but quite simple to do unless you want excessively thick flanges on the bronze bearing.

[55fairlane]

It must be nice to have those larger clamps mics Though they look mor elike 5-6" to me

Ah the bearing pedestals, they were one of the items that I felt were rather chunky. I think the castings could still be used if you wanted to do so. Just reduce the overall size so the foot is smaller and then step in again to further reduce the upper body. Easier if the protruding round bosses are done away with and preferably changed to flanged split bronze bushes but you could stick with the aluminium and use a rotary table or similar when reducing the thickness to leave a boss standing proud. Radius corner mill will leave a nice fillet for that cast look.

It is very likely that the model was inspired by the B Hick & Sons engine, if you click the image in this link it comes up a lot larger and you can see the much less bulky bearing pedestalls

https://www.gracesguide.co.uk/File:Im1851Cat287b.jpg

I would also make the smaller cylinder pivot bearing pedestal a bit nicer, a smaller version of the main one at the front.

Thank you for the picture....any pics of actual engine?

Those mics are 4-5 , 5-6  & 6-7 .....

[55fairlane]

Something like this looks more like the engraving. The green represents the top of the standard so you can see the "foot" has been reduced and also the further reduction of the main body. You could arch the top if you wanted to make it match the bearing ones but I have gone for similar to the engraving but put 4 external fixings rather than having to use the cap retaining studs right through.

Would need slight work to the crank arm and crank shaft so that the shaft can be located without moving axially but quite simple to do unless you want excessively thick flanges on the bronze bearing.

I'm thinking very similar to you....on the splits (that retain  the bearing) I may bring the screws in from the bottom just to hide them.....I have a bunch of square cast iron & leaded bronze I may make square bearing blocks.....I'm gonna need to do something to keep the crank/flywheel from moving, at present the upper bearing blocks give it .100 or so of float and the cylinder retains the entire reciprocal assembly......

[Jasonb]

I don't know of an existing engine.

Many engines of this time would have had a reduced diameter where they ran in the bearings and that would give axial location. You can do it by turning the smaller diameters or a simpler way would be to use 0.500" ground material and then turn up some sleeves that could just be slipped on or held with Loctite., though they could be left loose. I would probably make the boss longer on the crank arm so it bears against the bearing and then use the sleeves between bearings and possibly one on the far end. Similar to the attached which I did on one of my engines. I tend to fully retain crankshafts and if some float is needed have the crank pin longer than the big end bearing that way you do not get side loads on the piston& rod, The loose sleeves can be adjusted for length at final assembly to get the required "fit"

Regarding how to fit the bearing caps. You have to be a bit careful with old engraving sas they often leave bits off or use artistic license for others. If you think how the engine would have been erected back in the day it is very unlikely they would have had fixings coming up from below, even sharing studs to hold the bearing pedestal and cap is not the common. More likely the pedestalls were held on studs and their positions adjusted and separate studs for the cap as you don't want to muck up the alignment of the pedestals if you just want to make adjustments to the bearings. The exception would be where the pedestalls were part of the upright standard casting in which case hidden screws could be used join the separate castings together and a bead of filler to form a fillet so it looks like a single casting

Same applies to that inlet/exhaust block, one single fixing from below is very unlikely both for the practicality of fitting it on a full size engine and not the best to keep things lined up as it could swivel on the single screw. There are other things that could do with altering on that block too.

[Sanjay F]

Not sure if this is a help or a hinderance but these drawings are great for the details https://www.modelengineeringwebsite.com/Hick_oscillator.html

[Jasonb]

They are basically an enlarged version of the King design that Hemminingway  and now Reeves sell. The King one was a lot closer to the engraving and better detailed than the  Keeley, and as the keeley is bigger the lack of detail and chunky parts is even more obvious

[55fairlane]

Sorry I have responded to anything as of the hour, my Friday was dealing with the insurance company of the kid who rear ended my wife's car & my yesterday was spent at a rifle match.....I faired well at the match, until 16 year old Jenna showed up....she is really good.... my 581-27X (600 point max) wasn't good enough, but still fun!

Lots to respond to.....when I started this engine I honestly had no idea it modeled on a past design.....I am going to be taking some "artistic license " as I build an engine that works and has the basic look of the Hicks unit......

The crank shaft design is very interesting....after i get the upper bearing blocks sorted out (at least on paper)  brain power is needed for the crank....lots to think about....

As far as the screws (fixings, to you tea drinkers) , all items such as bearing pillars, bearing blocks, ect will be located with a dowl pin and screws, I'm not after a perfectly correct model of an engine, just a good runner

Thank you all for the historic information,  as I think about all the things that need sorted out.

Lots to digest

[55fairlane]

Got back on the engine, Sunday I pulled the vise, cleaned the table, clamped the work down & squared it up.....Monday I did some math......tonight I cut bottom, both sides (top & bottom) to finish, and cleaned up the top surface ( .025 still on it for finish) actual machine time, 31 mins start to finish....one more feature to do, it can wait until tomorrow. Or the next day
My plan is to drill/tap the bottoms, install the pillars on the base, true up the tops while installed on the base....this should keep things very true, flat & square

[propforward]

Great progress, and top attention to detail as usual.