7mm Rob Pulham's Work Bench - Back (again) to the LNER 06 (MOK 8F)

[Rob Pulham]

Well the bit that many have been waiting for the A3 is almost there!!!

I got the body back on this afternoon but despite running fine on the rolling road, put her on the track and she just died. I have to admit to being almost at the point of throwing the towel in and putting her in a cupboard to rot...

Chris came to the rescue and after 3 hours of frustrating diagnostics we (she) narrowed the problem down to dodgy connection in the plugs that joint the loco and tender (I am using the american pick up method).

These will be replaced tomorrow and hopefully there might be video in the offing. The eagle eyed among you will not the absence of a few bits - the revering rod which still needs cutting to length and the angled rod that goes under the right hand side of the cab which I seem to have misplaced. I still need to work out how the front buffers fit too but at first glance it looks like I have lost two of the springs for them too....

On to the photos:



What appears to be a rod under the draw bar is the connecting wire (the one with the faulty plugs....) which I haven secured yet.

 

[john lewsey]

Rob that's lovely

 

[Ressaldar]

well done Rob, award yourself a CDM Easter egg - but wipe your hands before handling the A3

cheers

Mike

 

[Rob Pulham]

Thanks Gents, I am really pleased with how she looks I just need to get performance to match then I will feel better about getting on with the 06.
Although painting the 06 should be easy now that I have perfected muck and rust

 

[Rob Pulham]

She's alive!!!

A couple of dodgy videos showing that she does move after all - after removing the offending plugs I still had issues which were narrowed down to one of the rear drivers shorting all sorted.

Apologies if anyone doesn't like Harry Potter the sound track was on the radio in the background

 

[Rob Pulham]

I mentioned above that I was missing the lever that is mounted under the cab on the fireman's side (ash pan lever?). I recall the original was a single etch that was a bit one dimensional with a couple of pins to locate it in the footplate.

Shamefully plagiarizing Richard's photo of DJ that he posted on Brian's A3 thread I made up this as a replacement from some scrap etch - it's not as elegant as the one on DJ but it's infinitely better than a missing etch



I still need to file the uprights down to allow them to be fitted to the footplate.

I am also still having problems with the wheels touching the underside of the body which are caused by the hobby holidays hornblocks. So I have decided to keep my eye out for a spare partworks chassis (they come up on ebay from time to time) and rebuild the chassis but only springing the centre drivers.

 

[mickoo]

Rob,

I'm presuming the hobby holidays horn blocks are sprung?, can you not just insert stronger springs?

 

[Rob Pulham]

Unfortunately not or to qualify, not on the rear ones which are causing the problem - they are sat under the rear frame spacer. I have already had to drill a hole in the spacer to tighten up the screw which helped but it's still seems to be causing a problem.

The new chassis is the last resort (I have to find one at the right price first) and while it seems like a major retrograde step. I now believe that I was too adventurous with what was my first tender loco in 7mm (and only my 3rd loco build in total) and that the issues are down to my inexperience - for example I should have cut the rear frame spacer and mounted the motor on the rear axle which would have solved some of my problems.

In the meantime I will persevere with what I have in the hope that I can solve the problems without building a new chassis.

It has knocked my confidence a bit and at the moment I am having a bit of a rethink about buying any more loco kits going forward (or in reality what I offer to Chris as potential birthday/Christmas gifts) until I have some of those I already have built and running successfully.

 

[mickoo]

Rob,

Before you get too dispondant have you got any photos of that area/problem, there may be an easier solution but I can't visualize where the short would occur unless it's on the firebox/rear splashers?

If you need to move the rear axle down a bit and can't get any more with the set screw, then you only need to take that screw out and add one with a longer thread, failing that, keep the existing screw but add a shim of brass to the top of the axle box, solder or some strong adhesive should suffice, start with 10 Thou shim and see how you get on.

Hope that helps

 

[richard carr]

Rob

Tell us more about the chassis as I find it very hard to believe that the hornblocks are the cause of the problem. Mick's advice above is good and would be the first thing I would try. Remember on a sprung chassis the loco rides on the ends of the screws, the springs should be fully compressed and are there to push the wheels down into any dips in the track.
How are the pick ups arranged ?

Poor running of a model is the most annoying thing going those 31s almost drove me mad.

Richard

 

[Rob Pulham]

Hi Richard,

Pick up is by the american method - drivers on one side shorted out and the opposite side on the tender with a paxolin drawbar.

After having a chat to Graham earlier today I am going to try lining the underside of the body with tape to hopefully prove one way or another where the short is.
Unfortunately because of the way the hobby holidays hornblocks are designed and the fact that the rear ones are under the frame spacer, it makes it very difficult to see how the springs are adjusted without stripping off the wheels.

My biggest problem is I suspect, in my head - I have been on with it for so long now that I struggle to raise enthusiasm especially when faced with problems.

 

[7mmMick]

Hi Rob,

I totally understand where you're coming from with this. I had a test run of my J73 (my first S7 Build) at Brightwell and it wouldn't run through the points I was totally gutted after all the work i've put in. I had just washered the wheels out too far and there was literally no movement. Also I had wound the centre axle screws down too far to the frames rocked over the centre axle. So with several on lookers my engine let me down and ran terribly.

A week away and with the screws adjusted properly and washers removed all seems fine. needless to say, I know the feeling well but with a short break onto something else then your mojo will be rekindled and the mountain won't seem as steep. You'll sort it pal, I'm sure of it,

ATB Mick

 

[alcazar]

Hmmmmm, what will it take to get mine back?

 

[Dog Star]

Hmmmmm, what will it take to get mine back?

A Heljan 7mm model... or maybe a JLTRT kit... for D1200.

 

[OzzyO]

Hello Rob,

at £16 (and that's the cheap ones) a pop per axle, don't give up. First take the body off and see if you can see any wipe marks (scratches through the paint), you should only have to look on one side of the loco. But if you can see wipe marks on both sides of the loco that's where you have the problem.

One thing that I'd check as well is that you have got the top of the frames parallel to the track (don't check this from the flanges do it from the wheel treads).

The big question is why have you only found this after you have done all of the paint work?

OzzyO.

PS. have you insulated the fall-plate between the loco and the tender?

 

[mickoo]

..... So with several on lookers my engine let me down and ran terribly.....

I think your being a little harsh on yourself, it was a sighting test and it did what it's supposed to do; it showed where the issues where and the spectators gave their advice, which it would appear, worked

Everyones a winner in my books.

 

[Rob Pulham]

The big question is why have you only found this after you have done all of the paint work?

That is indeed a good question - it ran fine (or seeemed to) before I stripped it down for painting......

PS. have you insulated the fall-plate between the loco and the tender?

Not yet, but I know that it's to do - so far I have been doing all my testing it with the tender in the last hole that I made in the draw bar which doesn't allow the fall plate to touch the tender.

I didn't touch anything yesterday but I feel a bit more like having another go to get it sorted today.

 

[OzzyO]

Hello Rob,

playing hunt the short is one of the most fun parts of loco building (not), a tip that I got off a friend and loco builder is to run the loco in the dark to help see the short.
These are not H.H. horn guides but I would expect them to look something like this.


When you have them in the frames, they should look like this. If the screws have a lock nut on them make sure that it's not hard down on the top of the horn guide, if it is turn the screw back to help unlock it.


When I'm setting up a set of sprung frames this is how I tend to do them (there are other ways), the weight at the front is only there to compress the front spring. In this photo I'm setting the middle axle, note the use of a shim (25thou.) to make sure that the middle axle can move upwards as well as down.


When I'm happy that the setting screws are in the correct position I lock them in place using Loctite 290.
I've had to drill some frame spacers to make sure that I could get to the setting screws, it's a bit of a PITA but sometimes you have to do it.

One thing I will say is don't give up and start thinking about building a new set of frames. Once you have sorted these out (and you will) you'll think what was all the fuss about. The main thing is you have a set of running frames.

ATB

OzzyO.

PS. if you want to have a chat about it drop me a PM with your phone No. land line only please.

 

[Rob Pulham]

Hi Paul,

Thanks a lot for taking the time to post the photo's above.

The hobby Holidays horn blocks look like this (sorry this was the biggest photo I could find).


I plan to have another look at it this afternoon but if I am still struggling then, I would appreciate the chat and I will PM my phone number.

thanks again.

 

[richard carr]

Rob

Why are you so sure it's the drivers ? Have you looked at the tender wheels it can be pretty tight in there too.

Richard