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[IanJ]

Now for the piston group; pistons, crossheads & piston rods. Pistons & crossheads are both 7/16" dia in brass. Pistons have 1/8" x 1/8" grove to take the piston seal. I propose to try 1/8 square graphite yarn. Pistons are drilled & tapped 5BA to take the stainless steal rod.
The crossheads are drill & slotted to accommodate the little end of the con-rod & then cross drilled to take the little end pin. I first drill a hole in the lathe then extended the hole to form the opening with a slot drill. The crosshead is also tapped 5BA to connect it to the lower end of the piston rod. The individual components were then tried for fit.


Before moving on to the valve gear I intend to assemble all of the components machined so far in order to achieve good fit &  rotation without tight spots or looseness.

[bfgstew]

QUALITY.


Are you going to polish all machining marks out and Brasso it to within an inch of its life as becomes of these elegant engines?


Stewart

[derekwarner]

Thanks for sharing Ian .....on October 17th you showed and mentioned reaming the Trunk Guide bores to 7/16"

Was this to provide trueness and parallelism, or to provide a desired surface finish?......the reason I ask is you have mentioned the good quality of the 'bronze' castings....and so to intentionally leave a tooling pattern in the bores to aid with retention of lubricity? as opposed to the benefit of a higher surface finish in the cylinder bores

I have also checked the Reeves WEB pages, & couldn't see an all up kit price.....or a listing of material to complete the kit?

Looking forward to the build progressing

Derek   

[IanJ]

Stewart,


Definitely not going to paint. Polishing has begun, easy to start, the difficulty is knowing when to stop!


Derek,


The trunk guides, along with other components, were bored were ever possible using a boring  bar in the lathe. The aim is to achieve concentricity without any tappers as the lathe is best suited for this. Regards the surface finish; the aim is always to try for the finest finish possible by a combination of a suitable tool profile & cutting speed/feed rates. Using the reamer was an additional process that further improve the finish. Many will go that little further (if size & equipment permits) & use spring loaded hones & oils to 'polish' the bore further.
With respect to lubrication; my view, based upon experience with full-size practice going back some 40 years ago was always to look to achieve the finest finish possible, (as mentioned above). Then, ensure that lubrication is delivered to all mating surfaces, either rotating or sliding by the use of Pressurised systems (oil pumps) or Non-pressurised systems such as drip feeders/oil cups etc., or a combination of both. In addition, pipes, drillings/passages are employed to distribute the oil through out the components. In order to ensure that mating surfaces are coated with a film of lubricant, oil-ways are often cut into one of the mating surfaces. I have no experience of ever relying on tooling marks (i.e. poor surface finish) to aid the distribution of lubricant as it would be so difficult to control & predict its effectiveness. An exception is the mating surfaces found on some machine tool slides that, as final operation of hand scrapping the surface is left with a pattern of marks comprising of very, shallow depressions (often referred to as "seagulls") to help with oil retention. But, that aspect of engineering is an altogether different story.
Returning to "model engineering" from "full-size" practice. I am sure there are many skilful people who fit complex lubrication system to their models, Steam Locomotion builders for one. Given the size of the "Marcher" I plan to add oil cups with associated fine drillings were I can & rely upon the frequent use of the oilcan.


Regards Reeves castings:-


On their web-site under "Stationary Engines" you will find reference to the Marcher. There you find various items listed. It is possible to buy just the drawings, the individual castings or a "casing set". No bar material or fixings are listed. Many, as I did will invest in the drawings before committing themselves to purchasing other individual castings or the complete casting set. Some prefer to obtain just a few castings machine other parts from bar stock. Such items are the trunk guides, although I machined them from the castings supplied they could easily be machined from a suitable piece of bar stock. It comes down to personal preference/cost. In my case, I initially purchased the drawings & successfully made the crankshaft at very small cost as I had piece of steel. I then purchased the casting set. Regards the Quality, I have found quality to be very good; no blow holes, hard spots & dimensionally correct.


Hope this answers your questions.


Ian

[IanJ]

All components machined so far have been assembled to check fit. The exception is the fitting of the pistons & rods down through the bore that are then screwed into the crossheads as I yet to make a tool as per George's design.


Prior to assembly I drilled oil passages/pockets in eccentric straps & added oil cups to the main bearings for the supply of oil.
By fitting a drill chuck on to the shaft to gain purchase the engine turns nicely although it's a little tight. However, there are no tight spots. Need to fit the fly wheel & dispense with the chuck, then ensuring it is always oiled just keep tuning it over as you walk past to "run-it-in".


Staring on the piston valve next, considering how best to hold it & the best machining sequence.

[Jerry C]

Keeping it well oiled, run it slowly with the drill. When the oil stops turning black it’s run in.
Jerry.

[ooyah/2]

`Ian,
 You are making a super job of the Marcher engine and I am glad that you decided not to paint it.
I was reflecting on a Borderer Engine that I made some years ago which was a piston valve and to stop steam leakage at the bottom of the valve box I made a seal which I can't remember how I did it, knowing that you are making your Marcher a piston valve and the dimensions of the valve box is clear I thought that I would suggest a method to stop steam leaks, my engines cylinder block and valve boxes were made from a lump of square cast iron window sash weight
.
So rather than trying to describe my method here is a free hand sketch of a possible way to seal the piston valve bottom.
My Marcher has Stevenson reverse and my drawing doesn't show all the dimensions  for the piston valve so I hope that I am not too far out with my guesses but you could alter to suit your valve rod.
 
George.

[ooyah/2]

Ian,


Just thought on a very simple seal with a bit of graphite packing, a Hex or a knurled nut is all that would be required as it only needs to be finger  tight if there is a small steam leak at the bottom of the valve.


George..
This suggestion means that you don't have to drill down and flat bottom the 1/4" reamed hole and instal an "O" ring

[IanJ]

Hi George,


Thanks for the comments & the suggestion of sealing the lower end of the valve. I am continuing with the machining of the piston valve bodies as per the Reeves drawing. The main bore is 1/4" through out its length except for the threaded portion at the top end to take the sealing plug. Your sketch shows a gland arrangement which would require the bottom end of mine to be reworked in someway. You mentioned the difficulties of achieving a seal on such a small piston valve earlier & the possibilities of adding a '0' ring if space & travel of the valve piston/spool permits. At the moment that's the way I am planning to go, although I may substitute the '0' ring for graphite string. I can try various arrangements on the spool without altering the valve body, that way the option of adding a gland as you suggest remains.
I envisage two issues; (1) getting all of the dimensions right that achieves the right "porting' as the drawings call for a 0.005" (0.15mm) overlap. (2) Sealing issues still persist.


The steam passages on both the piston valve body & the matching one in the cylinder head differ to that of the slide valve version. For that reason I have not yet drilled the steam passages in the head, just incase I need to abandon the piston option & revert to the slide valve version. I hope to complete piston valves & get them to stage were I can try them on "live" steam in order to test both function & seal before I commit to adding steam passages to the head. Any views on such an approach?


Ian

[IanJ]

Hi George,


Just seen your latest post. I like you alternative arrangement as it avoids the need to put a grove in the piston/spool & allows for adjustment.


Looking to post photos of the work done to date soon.


Ian

[ooyah/2]

Hi Ian,


My alternative suggestion I think is the simple solution and there will be enough metal to thread the bottom 3/8 x 32.
Try it out on steam and see how it goes and if there is a leak you can always reduce and thread the end as there looks to be enough metal to do so.


George.

[IanJ]

The photos show the machining sequence for piston valve bodies. Set up in the 4 jaw chuck & centred around the rough casting the first step was to drill & ream the  1/4"bore. The important dimensions are the face of the valve to the centre of the bore & the location/size of the ports as all other are in "fresh air". I nevertheless decided to clean-up the outside diameters where possible to improve the look & to help with holding.
[/color]
[/color]Using a piece of precision ground bar (that will be subsequently become the pistons), the body was set-up on "V" blocks that allowed the marking out of the various ports etc. from the bores axis. Using this datum it indicated how far out some of the cast lugs can be, although this is not major consequence. This axis was also used to directly measure the distance to the valve face when in the mill. Subsequent photos show the steam passages drilled then plugged. The final photos show cleaned up pair of valves & their associated end caps (not yet sure if the size of hex's look right).
[/color]
[/color]Ports in the valve faces need to drilled & piston made.

[ooyah/2]

Hi Ian,


I read that you are going to make the Piston Valves from ground steel ,  ground steel is  mild steel, I don't know what grade, and the valves made from this material will rust rapidly so I suggest that you make the valves from St/Steel, once made and installed you can forget about them.


ST/steel from most of the suppliers is usually .0005" undersize so this may account for the leakage at the valve bottom but if you use as suggested with graphite packing it only requires the gland to be finger tight to stop any leaks.


George.

[IanJ]

Hi George,


The precision ground steel is: EN1A, free machining mild steel. I am away at the moment, so do not have access to the drawings but I am sure that they did not specify stainless steel. I was intending to feed oil through the engine following a run to prevent rusting, in fact by removing the screwed plugs from the valves you can easily squirt oil in directly. Unlike many other engines having cast iron comments the 'Marcher" has only one internal steel part; the piston valve spool. So the point you make is very valid one.


Although I have made 1 spool already, which appears to function well, I can easily make additional ones out of stainless steel, once I get some.


Ian

[IanJ]

The "Marcher" drawings do not specify the material for the valve spool. Interestingly, the drawings for "Borderer", which is virtually a bigger version of the "Marcher" does however specify stainless steel. George is correct, stainless is the way to go, there is no value in making them out of anything else.
I have completed the valve bodies by drilling the ports. As the dimensions are critical I used a DTI in order to get the spacings right.
I went on to complete one set of the connecting rods/adjusting yokes. With a valve body and connecting rod components set-up with a gap between it and the cylinder head I intend to try it on "live steam" not only to check its function but more importantly see how good or bad seal is before I try seal options.


On a more general note. The "Marcher" is quite a small engine, which is its appeal, however it's also very heavy for its size. I estimate it will come in at some 840g. Of that, the fly-wheel is 185g. That's over 20% of the total weight. In my mind that's lot of mass revolving on what is small shaft of 1/4". I have Stuart Compound Twin; bores of:- 1-1/4" & 3/4" and its fly wheel is only 1g. heavier than that of the "Marcher"l. Any observations would be most welcome.

[frazer heslop]

Hi Ian, once she has freed up simply do away with the flywheel
I ran my engine with no flywheel fitted in a Thames style launch with no ill effect on performance . I think it was more responsive
cheers

[ooyah/2]

Hi Ian,


Very neat work and the engine is coming along fine.


What is the reason for the spacers between the Cylinder block and the piston valve casting ?


Regarding the Marcher's weight mine comes in at 2 lbs including the boiler feed pump and I agree that it's a heavy little beast but like you I really like it.


The flywheel on mine is 1. 325" dia with the centre heavily milled out  , another attempt to keep the weight down, had I known the eventual weight outcome I would have made the base plate in Ali rather than 10 SWG brass. but it's a fine little runner.


George.

[IanJ]

Hi George,


I have not yet drilled the corresponding steam passages in the cylinder head that match the piston valve. The steam passages are located at different centres depending on the type of valve body chosen. I thought if I packed the valve body a little distance from the cylinder head it would allow steam to flow whilst still maintaining the relationship with the eccentric etc for testing . If I can not achieve a seal on the piston valve, I will abandon the idea & build the slide valve version and commit to adding steam passages to the head. It will mean machining alternative eccentrics & linkages etc but as you have pointed out before steam leakages will not be an issue. I will of course, also need to add reversing gear.


Regards the weight, I am also planning to loose some more mass from the fly wheel, but it still seems heavy in proportional terms to the engine.


Frazer, you make an interesting point re value of fly wheels at all. I suppose a coupling disc is the minimum that is needed and a selection of discs can easily made for trials.

[frazer heslop]

Hi Ian, dont forget the prop should and I believe does give some flywheel effect
The Mb22 has no flywheel although it has some larger webs in the crank design
Good luck with the piston valves for some reason they gave me a lot of grief getting a running fit without leakage.
cheers

[IanJ]

One of the piston valves now tested with live steam. Steam (or a lot of water vapour) issued forth from the ports as the engine was turned over and condensed on the various parts. There was however, no leaks from the bottom of the spool.


Not sure what it proved as the valve body was set a little distance from the cylinder head & the steam could easily flow through the valve, so it must be assumed there was not much pressure within the valve body. I intend to repeat the test with the valve body fitted to the cylinder head and see what degree of leakage there is then.
 

[IanJ]

Having been away, then Christmas, plus other distractions its been some time since I last posted on Marcher Build. Following Georges advice regards using stainless steel for the valve spools I ordered various diameters. Whilst waiting for delivery I made up a piston fitting tool (again thanks to George) to assist with the assembly of the engine & subsequent maintenance operations.


On the piston valve version reversing is achieved byway of 4 port valve i.e. : Steam. in/out & forward/reverse. The valve body is in two parts, between them is a valve disc mounted on a spindle. Again, with the stainless steel still a day away I made a start on the valve.


Two things then occurred that has prompted me to abandon the piston valve version and instead make the slide valve version with Stevenson reversing gear:-


(1) I feel that the completed reversing valve will be just to big in relation to the engine and will lack elegance alongside the engine, see photo of valve alongside that of the cylinder head. Also, it's heavy and adds more weight to what is already heavy little engine.


&


(2) I snapped off a HSS drill in one of the valve ports that is well and truly embedded resulting in ruined component.


Work will now commence on the side valve version. I now need a further two more eccentric straps, four new eccentrics as the 'throw' is different to that of the side valve engine. I will now need some form of throttle valve, but this can be more elegant and I feel more in keeping the with the size of the engine.


Ian

[Moxis]

Very interesting build blog indeed Ian. When thinking what to build next, I have considered a lot about this Marcher engine and some nice wooden open sloop project.
But in the beginning you said that your engine is intended to power a relatively small boat. Could you explain, what would be the correct size of the boat which would suit Marcher engine? And how big boiler would be needed to supply the Marcher? I am not very keen to fabricate the boiler too because I lack the eguipment & skills to do proper silver soldering, so my intention is to purchase it from a suitable source and that's why I am asking.

[IanJ]

Hi Moxis,


I feel that there are many others that are better qualified to comment on engine/boiler/hull size combination. Nevertheless, my view is that although the Marcher is relatively heavy for its size the bores are only 7/16" (12mm) diameter. So I believe that the steam consumption will not be that great and that a boiler of 3 1/2" (90mm) diameter would be suitable. In fact, a 2 1/2" (65mm) may do. I also do not have the desire, skill or the equipment to make a boiler so will purchase one when the time comes. Boilers made by Pendle  Steam have a good reputation as testified by many contributors to this forum.


Regards the hull size; I am looking at an open hull of something less than 900mm.


I would welcome the views of others.


Regards


Ian

[rhavrane]

Bonjour Ian,
A friend has ordered a 4,5" horizontal boiler for a D10 and I have ordered a Kingdon one to Nigel (Pendlesteam). They will arrive soon. I will be happy to share our experience with you. First feeling, Nigel is really listening to his customers, he has made special adjustements for my requirements, he gives pictures of his progress and his prices are "reasonable", despite a pound high compared to €uro. 

[IanJ]

Hi Raphael,


Look forward to hearing about your experience of your new boilers.


ian