7mm David Andrews Princess - 6206 Princess Marie Louise

Dave Holt

Dave Holt

Western Thunderer
Rob.
The ball race eccentric rod bearings were grease lubricated and had no visible "oil corks". The small end of the rod, where it attached to the expansion link had a grease lubricated needle roller bearing with no oil pot or cork. I presume these bearings had a grease nipple somewhere, but it's not clear in photos where these were.
Dave.
 
Rob Pulham

Rob Pulham

Western Thunderer
Dave Holt said:
Rob.
The ball race eccentric rod bearings were grease lubricated and had no visible "oil corks". The small end of the rod, where it attached to the expansion link had a grease lubricated needle roller bearing with no oil pot or cork. I presume these bearings had a grease nipple somewhere, but it's not clear in photos where these were.
Dave.
Click to expand...
Brilliant,
That saves me a job.

Thanks again Dave.
 
bambuko

bambuko

Western Thunderer
Rob Pulham

Rob Pulham

Western Thunderer
Still beavering away at the chassis. I had it running with just the inside motion for test today. Actually I had it running last night but then I realised that I had one of the insulated wheels on the wrong side so had to strip the rods off to swap it around.


As an aside I have reversed the front crankpin bushes to look more like the prototype and to give additional clearance for the motion. I was wondering about how to tighten the reversed bushes and remembered the late David Smith talking about making peg spanners as he called them. I chose a similar route but instead of pegs I used the same approach as the 4mm scale Romford screwdriver (I still have one in my modelling toolbox).

For those who haven’t a clue what I am talking about this is a Romford screwdriver

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Original Romford Screwdriver

This is the leading crankpin bush that I am talking about

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Front crank pin nut

This is the custom big boy’s ‘Romford’ Screwdriver that I made to tighten them. The business end is 3/16 silver steel and the end was shaped with a 3mm end mill with the rod held in a square collet block so that I could keep flipping it over to take the same amount off each side.

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8BA Romford Screwdriver

Continuing my current ‘Dremel’ tool theme I used a ball burr in the mill to make the grip.

Previously I have used the ball burr in a similar manner to an end mill by cutting into the top of the work piece. This time I did it differently and side milled it. This gave a much better finish and was easier to do. I milled the grooves before turning the taper.
 
Rob Pulham

Rob Pulham

Western Thunderer
michael mott said:
Nice work on the screwdriver Rob. Sometimes you just have to make your own tools.
Michael
Click to expand...
Thanks Michael,
I do like making tools, and I enjoy using them even more.
I still have a couple of tools that I made in metalwork class at school in the 1970's which I use whenever possible.
 
Rob Pulham

Rob Pulham

Western Thunderer
The last couple of weeks have been steadily working towards getting the outside motion working as smoothly as the inside motion. It has fought me much of the way.

Some of the issues have been of my making, mostly due to my clumsiness in dropping bits on the floor which subsequently disappeared into the black hole in the workshop floor.

As I was working my way through the motion and I got to the motion bracket, I discovered that he support rod for the reversing mechanism wouldn't go through the chassis due to it hitting the middle wheel set.

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Initially, I wondered if the cast wheels were slightly oversized but they aren't and a bit of further investigation got me to the support brackets which are too long when compared to the GA drawings in the Wild Swan book. I wonder if other people who have built the DA kit have experienced the same issue?

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Rob Pulham

Rob Pulham

Western Thunderer
chigley said:
are the lifting arms to long as well Rob

Ken
Click to expand...
I don't know yet Ken. I am in the middle of making replacements for the support arms.

It seems that there is an error in the etches as John Dale has experienced the same issue with his build. Which at least gives me the comfort of knowing that it's not as a result of some error that I have made.
 
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adrian

adrian

Flying Squad
Sorry to throw another small spanner in the works but the expansion link doesn't look quite right either, specifically the bottom link for the eccentric rod. On the kit the bush centre is almost inline with the curved outline of the expansion link whereas on the prototype photo there is quite a marked kick back to the bush. On the kit I don't think you'll get the expansion link to the same position as shown in the prototype photo as I suspect the eccentric rod bush will strike the motion plate.
 
mickoo

mickoo

Western Thunderer
The radius rod isn't right at all, look at the front end and the valve die block is almost out of the slides, the hole for the pin in the middle of the expansion link is too far away from the slot.

That still doesn't solve the overly long bracket holding the lifting link bearing (but then this is something quite common on DA kits, the 7F was all over the place) or as Adrian has noted, the incorrect profile of the expansion link.
 
Bodger Bill

Bodger Bill

Member
Rob,

I agree with all the above, but I also wonder about the ride height.

To my eyes, the drivers look to be set too high up in the frames. If you look at the actual loco, the cylinders incline downwards towards the rear. Taking a line along the piston rod, through the cross head, this line would meet the middle driver axle centre. This puts the line, and hence the pivot in the crosshead, slightly above the centre of the leading driver axle.

On the model, the cross head pivot appears to be below the crosshead pivot (trying to allow for and possibly fooled by the camera angle).

If they are too high then this would contribute to the centre drivers fouling the lifting link pivot stub.

Keep up the excellent work.

Ian M.
 
Rob Pulham

Rob Pulham

Western Thunderer
Thanks for the observations Gents, they are appreciated.

Some dismantling and measuring later, has determined that the Radius rod is actually slightly short rather than being too long. but Adrian is correct in that the hole for the pin is 1mm too far away from the slot. That should be a simple fix but I am not sure what I can do about the kick back on the bottom of the expansion link. I have some cast examples in my spares box that are labelled LMS but they are pretty much the same as the ones fitted.

As Ian observes, I haven't sent the final ride height yet. All I have done is ensure that the chassis is level so far. Unfortunately, lowering the ride height isn't going to give me the clearance that I need for the reversing support rod.
 
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