7mm At the Western End of F7

[adrian]

The clearance of the brake block is set at this stage by defecting the wheel to mid position, moving the brake block and suspension arms to the required position and then supergluing the block, pin and arms together to lock the position. I used a medium CA. Again no swearing, etc!

Thanks for the update - that looks a very neat arrangement for springing. Are those brake blocks from your printer? The quality looks impressive - I was going to make a subtle joke about Russian engineering but not everyone appreciates my sense of humour (defecting vs. deflecting) and I'm always conscious of Muphry's Law.

 

[SimonT]

Thank you Adrian, the brake blocks are from the printer. More picies to follow. The joy of the speel checker! One of my colleagues had a piece of doggerel on his office door where every word passes the spell checker but is totally wrong in language and context. While Murphy can raise his head, more often than not it is my brain-finger interface that is at fault.
Simon

 

[daifly]

Something like this?

Eye halve a spelling chequer
It came with my pea sea
It plainly marques four my revue
Miss steaks eye kin knot sea.

Eye strike a key and type a word
And weight four it two say
Weather eye am wrong oar write
It shows me strait a weigh.

As soon as a mist ache is maid
It nose bee fore two long
And eye can put the error rite
Its rare lea ever wrong.

Eye have run this poem threw it
I am shore your pleased two no
Its letter perfect awl the weigh
My chequer tolled me sew.

 

[SimonT]

Absolutely! We had a 4 layer QA system that made you want to weep when a document, that had taken many months work, came back covered in stickits and comments. Later you got to QA others work and saw that they were just the same as you. Despite the QA effort there were still mistakes in mature 15 year old manuals, that had been amended and QA'ed twice a year, which had been there since the first edition. Put a human with a computer and ...watch the mistakes roll.

 

[adrian]

While Murphy can raise his head, more often than not it is my brain-finger interface that is at fault.
Simon

I blame my parents for my affliction - they were both teachers and I was very careful to link to Muphry's Law

Muphry's law is an adage that states that "If you write anything criticising editing or proofreading, there will be a fault of some kind in what you have written." The name is a deliberate misspelling of Murphy's law.

 

[SimonT]

And I have just proved that people read what they expect to read on a computer screen!

 

[OzzyO]

And I have just proved that people read what they expect to read on a computer screen!

Pardon, if something is wrong why not let us all know what is wrong?

Question .

OzzyO.

 

[adrian]

Pardon, if something is wrong why not let us all know what is wrong?

Not sure what you're referring to?

As far as I'm aware nothing is wrong, I made a comment about Muphry's law, a lot of people would read that as Murphy's Law, which is what happened here. Note the difference in spelling. That's all that Simon was referring to.

 

[SimonT]

New toy time

The post man has just delivered the latest bit of NS from PPD. These are S7 frame spacers for the David Andrews 42/52XX. I produced the first set the old fashioned way but decided that as both the Welsh Wizard and I needed a set that I might as well produce the artwork. The frames will have the prototypical joggle that allows the rear wheel set to get around the odd sharp corner or two found in these parts.



Simon

 

[SimonT]

Ignoring the new toys I thought I ought to push the Blue Peter 42Xx through to the finish. Trial fit of my printed brake shoes and arms showed a problem....


The cylinders sit 2mm too high because ......

They are resting on the brake arms (they have flopped open in taking the photographs). Now the brake bits fit exactly over the GA drawing, so there has to be something else wrong. Thanks to the GA I now know that the cylinders are just over 1mm too far back. If I move the cylinders forward the cross head will be outside the slide bars when at the rear. Alternatively should I carve a large chunk out of the back of the cylinders to house the brake arms?

Any bright ideas?

Simon

 

[Dikitriki]

If it were me, I would relieve the back of the hanger a little, and thin the brake shoes as necessary - assuming that gives you the right angles etc.

Oh, the joys of not quite right kits, of whatever manufacture

Richard

 

[SimonT]

Richard,
a fine idea only spoilt by my having just printed two loco sets of brake gear, all the arms and shoes would need to be adjusted and reprinted as the pull rod and equaliser beams are etched as one piece. I failed to spot the problem at a more convenient time by trying the prototype arm and shoe on a different wheel.

I am going to go with the hack at the back of the cylinder as I have already removed some metal. There will be too many pieces of metal in a confined space to see what I have done. Just don't tell anyone!

The next question is what to do on the next loco?

Simon

 

[SimonT]

Mick,
good idea but the dimensions of both the slide bars and the crank pin throw are correct to the frame plan. My brake arms are, if anything, inside the position of the brake arm on the drawing. I think that the brake pivots are too high compared with the drawing, although the drawing is very congested in this area. I may have to make a compromised brake arm to adjust out the error. The next one can have to brake pivots dropped as it is still in the flat.

Simon

 

[OzzyO]

Mick,
good idea but the dimensions of both the slide bars and the crank pin throw are correct to the frame plan. My brake arms are, if anything, inside the position of the brake arm on the drawing. I think that the brake pivots are too high compared with the drawing, although the drawing is very congested in this area. I may have to make a compromised brake arm to adjust out the error. The next one can have to brake pivots dropped as it is still in the flat.

Simon

Hello Simon,
if the slide bars and the crank-pin throw are correct but the cylinders are 1mm to far back, then by the sound of it the connecting rod centres may be out. That would explain why if you moved the cylinders forward the cross-head would come off the slide-bars.

OzzyO.

 

[SimonT]

Ozzy,
interesting idea. Frame plan measures 47.5mm. model connecting rod measures 48.5mm.
Good spot, now to work out a way out of here!

Simon

 

[adrian]

Puzzled of Preston here. Shouldn't the connecting rod be too short by 1mm, i.e if the cylinder needs moving forward by 1mm and thus the conn rod lengthened by 1mm to match the frame plan?

 

[SimonT]

Dear Puzzled of Preston,
you would should be correct. At the moment I don't know which dimensions are right.
Yours,
Equally Puzzled of Wiltshire (now back to 'Quins v Saracens)

 

[OzzyO]

Very confused of 11B? I would say the next job is to check the wheelbase to the drive axle, as if the con rod is 1mm long and the cylinders 1mm back there is 2mm that is going somewhere!

OzzyO.

 

[SimonT]

Fellow Puzzlers,
I may have found the answer.
Firstly connecting rod. The rod lies over the paper fold of the GWJ. Very careful flattening of the paper brought the length up by .5mm and using a digital caliper brought the length of the model rod to within .2mm, so acceptable.

Second is the essential measurement of the centre line of the cylinders to the centre of the leading axle. The drawing has a measurement of 5ft, so 35mm. The model cylinders sit between two etched slots front and rear. I measured the distance over the outer faces of the slots and this was 25mm, so a line was scribed at 12.5mm. Now accepting that the wheels and rods will make establishing the centre of the axle a little iffy, I measured the distance and came up with 34mm. So this confirms that the cylinders are about 1mm to close to the leading wheels and explains why the cylinders clout the brakes and thus the wheels.

Simples? Thanks chaps

Not Quite So Puzzled of Wiltshire

 

[SimonT]

Rather than post the promised pictures of the Peak bogie on Richard's thread, I have decided to place them here.

Firstly a view of the completed bogie. The inner and outer are joined by the rear cross member and the by the front croos beam which has been reversed so that the former front face is now the top face. Three bolts keep everything in place, unlike the JLTRT arrangement where the vertical slots which the bolts go through ensure that you spend half an hour bolting all together. There is no rocking pivot to the bolster but there is a small amount of movement allowed by a compression spring under the retaining nut; this is needed to get the bolts in that hold the chassis to the body. One of the pick ups has slipped off the wheel and this has been corrected.


A view of the swing link for the leading wheel. The lead sits on the flat top of the bogie and clears all the other gubbins. The truck can float up and down by about 1mm, which is more than enough.


A view of the compensation beam with the axle bearings fixed to the beam. The beam pivot is a 2.5mm tube on the main frames and a larger tube on the beam that fits over the main frame tube. A 6BA bolt through the middle keeps everything together.


Overall I am satisfied by the result and the loco runs everywhere on the layout that it did before. Best of all is that it now goes into new bits and it is currently sat in the yard, a place of former falling off.

Simon