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Martin Finney Hall in P4


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Guest Lyonesse

I would seriously urge you to follow Gordon's advice on this. The Gibson crank pin bush should fit over the Chassis Squared jig pins. Are there any burrs in the hole that prevent fitting? I had no trouble with mine in this respect but I have found that Gibson stuff can be a bit variable. Does the bush fit over the crank pin without a problem? Try gently running a 0.9mm drill through the hole to clear any swarf or burrs and gradually increase it to 1mm. Also worth measuring your drill bits before doing this as the cheaper ones are often under sized.

 

Regards

 

Mark Humphrys

Not sure of the current situation, now that AG himself has been retired for some years, but Alan Gibson turnings were always made with a very generous tolerance.  Indeed, AG said as much when he was interviewed in MRJ many years ago.  Bearings in particular, are very sloppy.  Which is why I stopped using Alan Gibson 2mm and 1/8in plain bearings.

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I have found that there has been a general improvement in quality under the new ownership;

Crank pin screws are now rounded off on the ends, no loose or distorted tyres on the wheels, and the crank pin bushes are a good fit on the crank pins.

 

Gordon A

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The bogie is now all assembled the forming the guard irons was tricky as well as pinning them in place with 0.45mm wire before soldering it all up. I like the control spring idea with the control wire going across the locating washer with the centre of the wire removed. Today I set up the Avonside Jig and using suitable long Gibson washers which would fit over the pegs I made up the Connecting rods and Coupling rods. I must say that the Crankpin fork joint was challenging to say the least. My method was just prior to soldering one end of the pin to soak the rest of the assembly in oil which did it job not allowing the solder to go and gum it all up. So the upshot is now I have two coupling rod sets which are to the correct size and pivot nicely about the fork joint.

All I have to do now is open out the holes for the Gibson Plunger Pick-ups and fit the rear step brackets to the chassis and then I will be ready to start the Cylinder Assembly. This I know will take some time as I have already build a Martin Finney Large Prairie.

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I have now done most of the assembly of the cylinders as well as the cross-head and connecting rod assemblies. Getting a nice sliding fit did take some time but should prove worth it. Now this brings me on to a potential mistake I may have made on the assembly of this unit. I am suspicious that I have managed to fit the slide bar brackets up side down as when I trial fitted the cylinder assembly to the main chassis I noticed that even though they slotted very nicely in to the slot on the front frame extension overlay the top of the slide bar bracket was not level with the cut out in the frames in fact it was about 0.5 to1 mm above it. So is there some one to inform me if I have managed to get it wrong even though my excuse is that in the instructions there is not mention of orientation and no diagrams showing the correct alignment. My problem being I have otherwise got the cross heads a very nice slide fit in the slide bars and trying to reposition the bracket will mean a lot more re fettling work as when I first fitted them I did notice a slight change in the quality if fit between the cross head and slide bars.

Otherwise I have also fitted the rear step brackets to the rear of the main frames and also opened out the holes for the Gibson plunger pick ups.

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In the photo showing the cylinders and slide bars in place, it looks to me as if the latter slope slightly upwards to their rear ends whereas the cylinders look parallel with the top edge of the frames. It may be an optical illusion, but if they do, that would explain why the support brackets seem too high.

Dave.

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Thanks for the feed back that has put my mind at ease. Next thing for me to do is add all the detail to the cylinder assembly this time using low melt solder cream. Then add the balance weights to the driving wheels ready for painting them prior to assembly and that lovely job the brake gear and then try out the triple lamination of the springs which if I understand the instructions correctly will hold the wheel sets in place.

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I have now finished fitting the cylinder drain cock linage and drain cocks. Regarding the drain cock levers they are too small for me to fit as if you try to drill out the etched holed at the end of them even a 0.35 drill is too big in diameter so I am going to leave them off. For the time being I have done nothing regarding the valve spindles as I am planing to fit working inside valve gear so soon some serious bed time reading of the instructions as how to fit the valve gear and get it working.

The brake gear I have made up so that it clips on to the brake cross shafts as a separate sub assembly. In order to do this I ordered a extra set of driving wheels form Alan Gibson which I have assembled and I use this set as a gauge to check not only clearances for the brake blocks but also side play as well as when I finally fit the other 3 sets I want them to go on only once as I feel that it is important to have a tight fit between the axle and wheel. By using what I call the sacrificial wheel set I found that the side play on the 2 rearmost was fine but for the front axle tight so I may have to carefully thin the horn blocks on the wheel face for this axle so as to get it free running. This has also proved the value of my idea of having a spare set to use for gauging.

I have made up the springs as per the instructions as a triple lamination and as far as I can see they will have to be either soldered or glued in place as by then self s they will not retain the horn blocks. So my idea at the moment will be to finish any detailing such as sanding gear on the chassis then paint most of it including red for the inside of the frames place the horn blocks in and solder the springs in clean up and paint them black. After this fit the pick ups wheels and inside valve gear.

Before I do this I am going to get the basic footplate assembled so as to check that it is a nice fit to the chassis before I paint it and that there are no issues there it also gives me more time to have fun working out the inside valve gear.

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The inside Stephenson's motion is actually quite straightforward to assemble. You only have to mount eccentrics on the axle, so no cutting required. Shouldn't take you long at all.

I made a set a while ago, intended for a Modified Hall. Took me under two hours.

 

EDIT: I should add that, if you are careful about spreading the rivets, you can get away with not using any solder at all, apart from the stuff you use for assembling the rods, eccentrics / dieblocks.

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Edited by Horsetan
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  • 2 weeks later...

First off thank you Horse Tan for the photos of the Stephenson link valve gear they will come in very useful. Anyway I have done the basic assembly on the footplate and it did require a little bit of fettling so that it fitted the chassis. The chassis is now in the paint shop and next time to get on with finishing the footplate and I must not put off getting on with building the inside valve gear. Lastly a question which some one may be able to answer for me would the eccentric rods and other parts of the motion be painted red .

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As you can see I have now done the basic painting of the chassis and fitted the bearings and soldered the springs on. Next I will paint the springs black and then on to fitting the driving wheels. Also I have managed to assemble the Stephenson valve gear and I am also painting as much of the links red as I can with out gumming it up. Once again thank you Horse Tan the photos were very useful indeed.
The footplate now has the splashers all fitted. The splasher tops did require a little bit of fettling as they were slightly too long to fit over the curves. Also I have made up and fitted the smoke box and boiler supports as well.
So I intend to fit the centre driving wheels and the valve gear as well as the front driving wheels. Then I will use the spare set of unpainted wheels temporarily at the rear with the motor and High level Gear box mounted and then check once I have the firebox assembled that there is enough clearance.

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  • 2 weeks later...

I have successfully fitted the inside valve gear and it all seems to work i.e. I can turn the centre driving wheels around with no jerkiness or binding allowing for the fact that I am using Alan Gibson plunger pick up which do produce drag as well as the valve gear it self with not only all the links in it there are the 4 eccentrics as well. So overall I am well pleased so far. When fitting the inside valve gear I had to cutaway the wire for the brake hangers which on most chassis I build I leave in place if possible and only normally remove inside if I want a motor or gear box to go in to that area as I find it adds to the strength of the chassis. I used Loctite 601 to secure the eccentrics in place and that was a bit nerve racking as I find that it does have a knack of going where you do not want it but at the end of the day it has worked out fine.

I then went and fitted the front driving wheels again I used the GW tool press to fit them. I also did a trail fit using the grey unpainted set I have just to check the side clearances and I found that I had to carefully rub the outside faces of the bearings down with 400 grit paper so as to stop the wheel set binding. Lastly regarding the Alan Gibson Pick-ups as I had to remove the shoulders of the pick-up housings I cut down the springs by about 1 to 1.5 mm so as to ensure that the plunger would go all the way in to the housing if required as there is very little clearance between the back of the wheels and the frame sides.

I then assembled the trail wheel set in unpainted grey with my proposed motor and gear box and found out that I had forgotten about the compensation beam cross shaft. Yes it clashes so back to the drawing board with a suitable High Level Gear box and motor. I am thinking of using a High Level High Flyer with a 14/26 motor this will also give more power than my original proposed set up. Before I order a new motor and gear box I am going to build the fire box boiler and smoke box first just to make sure I am going in the right direction. With that in mind I made a start on the firebox and according to the instructions I have to space out the firebox front and rear to a outside distance of 32.5mm using suitable spacers and then solder on the outer wrapper after folding bending etc.. My solution to this is to use suitable studding my first choice of suppler Eileens Emporium were out of stock so I am awaiting this studding from another supplier according to there website it has been dispatched to within a few days time I should have it.

Lastly a question the front plate of the firebox has what I would call a key hole slot at the top on one side what is it for and what is the correct orientation for it on the RHS or LHS? Any one got any ideas?

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I have successfully fitted the inside valve gear and it all seems to work i.e. I can turn the centre driving wheels around with no jerkiness or binding ..... I used Loctite 601 to secure the eccentrics in place and that was a bit nerve racking as I find that it does have a knack of going where you do not want it ....

 

The use of Loctite 601/603 is probably the lesser of three evils. I got away with a force-fit of the eccentrics on the axle (evil two). If you've got the right technique, you can solder them to the axle (evil three).

 

If I remember correctly, the notch or keyway in the firebox former can be used as a channel to thread the motor cables through to your pickups, especially if you are using the RG4.

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Guest Lyonesse

The eccentrics can be force-fitted to the axle, with care. This eliminates the need to solder them to the axle.

 

I have successfully fitted the inside valve gear and it all seems to work i.e. I can turn the centre driving wheels around with no jerkiness or binding allowing for the fact that I am using Alan Gibson plunger pick up which do produce drag as well as the valve gear it self with not only all the links in it there are the 4 eccentrics as well. So overall I am well pleased so far. When fitting the inside valve gear I had to cutaway the wire for the brake hangers which on most chassis I build I leave in place if possible and only normally remove inside if I want a motor or gear box to go in to that area as I find it adds to the strength of the chassis. I used Loctite 601 to secure the eccentrics in place and that was a bit nerve racking as I find that it does have a knack of going where you do not want it but at the end of the day it has worked out fine.

I then went and fitted the front driving wheels again I used the GW tool press to fit them. I also did a trail fit using the grey unpainted set I have just to check the side clearances and I found that I had to carefully rub the outside faces of the bearings down with 400 grit paper so as to stop the wheel set binding. Lastly regarding the Alan Gibson Pick-ups as I had to remove the shoulders of the pick-up housings I cut down the springs by about 1 to 1.5 mm so as to ensure that the plunger would go all the way in to the housing if required as there is very little clearance between the back of the wheels and the frame sides.

I then assembled the trail wheel set in unpainted grey with my proposed motor and gear box and found out that I had forgotten about the compensation beam cross shaft. Yes it clashes so back to the drawing board with a suitable High Level Gear box and motor. I am thinking of using a High Level High Flyer with a 14/26 motor this will also give more power than my original proposed set up. Before I order a new motor and gear box I am going to build the fire box boiler and smoke box first just to make sure I am going in the right direction. With that in mind I made a start on the firebox and according to the instructions I have to space out the firebox front and rear to a outside distance of 32.5mm using suitable spacers and then solder on the outer wrapper after folding bending etc.. My solution to this is to use suitable studding my first choice of suppler Eileens Emporium were out of stock so I am awaiting this studding from another supplier according to there website it has been dispatched to within a few days time I should have it.

Lastly a question the front plate of the firebox has what I would call a key hole slot at the top on one side what is it for and what is the correct orientation for it on the RHS or LHS? Any one got any ideas?

As Horse says, the keyway is for the power leads to the motor.  You get to chose which side to put it on.

 

For the 'suitable spacers' to join the firebox ends I use long L-shaped tinplate spacers, soldered in place.  Careful work with vernier calipers, a flat surface and an engineer's square is needed to get the sizes right and to get everything soldered up square.  The spacers can be easily folded in on themselves and pulled out once the wrapper is soldered on.

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Remembering the AGW driving wheels, these are more or less correct for the pre-1930 6ft wheel. The post-1930 wheel had webbing reinforcement adjacent to the crankpin, which is what Ultrascale makes.

 

In service, of course, it wasn't unknown for the two types to be mixed on the same engine.

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  • 2 weeks later...

At last got the 8BA studding. Using this I cut two lengths about 70mm long and then using plenty of 8BA nuts set up the firebox formers 32.5mm apart. Then using a 6mm diameter rod I very carefully bent the firebox wrapper so that it was a reasonable fit to the formers and then soldered it up. I used the notched on the formers so as to get everything central. However I noticed that after I had done the basic soldering that I had not got the front former correctly positioned It was out by only 0.25mm but enough to be irritating so I undid it and re soldered it in to what I felt was more accurate.. Then I carefully rounded the front of the firebox as best I could so as to get something which is close to prototype shape. Then I had to do some fettling so as to get a nice fit between the firebox and footplate after I had soldered on the cab front plate. Once I was happy I soldered it on to the footplate in some areas the solder on the joins between the bottom of the firebox sides helped to fill any slight gaps caused by my fettling to get the sub assembly to fit on to the footplate.

Regarding the 4 mud holes which go on the top of the firebox on the corners how do I get a good fit as they have a flat bottom and they should ideally go on to a curved surface on the firebox side top corners. Anyway I have also finished the sanding gear and the reversing lever.

I have not got any photos yet but I have built up the boiler and smoke box s well as a High Level High-flyer gear box so soon I will post some more photos showing further progress.

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Guest Lyonesse

> Regarding the 4 mud holes which go on the top of the firebox on the corners how do I get a good fit as they have a flat bottom and they should ideally go on to a curved surface on the firebox side top corners.

 

Just press them round a suitable former --- I think I used the end of an 1/8 drill.  For something Like this I place the cover across the slightly open jaws of the vice and gently press the drill, parallel to the vice jaws, into the gap.  If you see what I mean.  It's surprisingly easy to get them to shape.  You'll probably want to clean up the ragged edge of the cover while its still flat, by rubbing it across a fine file or some emery paper.

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