K's GWR 63xx - New P4 chassis options, suggestions

[Craigw]

1 hour ago, Mark said:

Is that taken from Ponsondane level crossing?

 

Regards

 

Mark Humphrys

 

Mark,

 

I am not sure where it was taken! I posted this and another in the GWR rolling stock special interest group. I won them both on Ebay a few years ago but no information is available on location. From the loco condition I think mid 1920s.

 

Regards,

 

Craig

[melmoth]

10 hours ago, Craigw said:

 

Mark,

 

I am not sure where it was taken! I posted this and another in the GWR rolling stock special interest group. I won them both on Ebay a few years ago but no information is available on location. From the loco condition I think mid 1920s.

 

Regards,

 

Craig

 

I think @Mark might be right. Link below to an image from the opposite side of the line at the same location at roughly the same date. The telegraph wires, pointwork and fencing would all seem to correspond.

 

http://www.cornwallrailwaysociety.org.uk/uploads/7/6/8/3/7683812/1121656_orig.jpg

[Jeff Smith]

On 02/01/2019 at 07:46, Miss Prism said:

Partially compressed.
 

The link above details the use of the Comet sprung hornblocks.

 

I have progressed with this model to the level shown in the attached photos.  The body was built enough to figure out the motor g/b space.  The M1024 motor and Branchlines Multibox and extender have been assembled with the extender unlocked at present pending final configuration, also final drive gear not fitted.  The chassis has been assembled with the centre sprung hornblocks installed.  New dummy spring etches were supplied as keepers but I just bent the attached springs enough to get the brass hornblocks in.  I opened up the slots in the hornblocks enough to get a slight rocking of the axle from side to side;  also filed the top of the chassis slots to give about a mm of additional upward movement.  The exact fore and aft location of the chassis to the body has not yet been finalised so the axles do not exactly align with the splashers in the photos.

 

I am concerned that the K's body will ride higher than the Bachmann body which the chassis is designed for but I'll have to do more work to evaluate this.

 

[DCB]

The firebox looks to be leaning back a bit, the boiler bands obviously should be vertical. Most drawings show the std 4 boiler with a horizontal top to the firebox though many models, K's 42XX for one have it sloping towards the back.  Likewise the Std 1 most drawings show the top Horizontal yet the K's 28XX slopes noticeably towards the back on most peoples models.

The GWR moved from wooden cab roofs covered in canvas(?) and tarred to sheet steel sometime during the 1920s.  The disappearance of the portholes may well date from this change which led to the "Rainstrips" als being moved

 

[Siberian Snooper]

Have you checked that the wheels will fit inside the splashers, I have expierienced problems in EM.

 

 

[Jeff Smith]

14 hours ago, DavidCBroad said:

The firebox looks to be leaning back a bit, the boiler bands obviously should be vertical. Most drawings show the std 4 boiler with a horizontal top to the firebox though many models, K's 42XX for one have it sloping towards the back.  Likewise the Std 1 most drawings show the top Horizontal yet the K's 28XX slopes noticeably towards the back on most peoples models.

The GWR moved from wooden cab roofs covered in canvas(?) and tarred to sheet steel sometime during the 1920s.  The disappearance of the portholes may well date from this change which led to the "Rainstrips" als being moved

 

 

The sloping firebox top and non-vertical boiler bands are unfortunately a 'feature' of the castings.  The right side bands look slightly better.  The lower rivet lines on both sides are actually pretty well parallel to the footplate.....  I had already decided to scrape off the bands and replace with something thinner but I might do a complete hatchet job and remove all the cast on features (except the rivet lines) and file the top horizontal - there's plenty of thickness - but it may then be too close to the top of the boiler.....

[Jeff Smith]

9 hours ago, Siberian Snooper said:

Have you checked that the wheels will fit inside the splashers, I have expierienced problems in EM.

 

 

 

There seems to be enough width, P4 wheels are narrower than EM although of course 0.83mm further apart...

[Miss Prism]

Mogul firebox tops do have a slope.

 

[Mark]

Using the GA in Great Western Journal it is about half an inch higher from front to rear. I have completely redrawn new boilers for my mitchell Moguls and spent quite a bit of effort puzzling over this but visually the new one looks correct.

 

Be careful of photos taken at rail level because the firebox is wider at the front than the rear and as such parallax can give some quite substantial visual errors.

 

Mark

[Guest Lyonesse]

18 hours ago, Mark said:

Using the GA in Great Western Journal it is about half an inch higher from front to rear. I have completely redrawn new boilers for my mitchell Moguls and spent quite a bit of effort puzzling over this but visually the new one looks correct.

 

Be careful of photos taken at rail level because the firebox is wider at the front than the rear and as such parallax can give some quite substantial visual errors.

 

Mark

Very impressive.  Doesn't seem to be much of the original kit left there.  Still, I'm as guilty as anyone of replacing boilers and fireboxes in MM kits.

[Jeff Smith]

On 24/07/2019 at 14:04, Miss Prism said:

Mogul firebox tops do have a slope.

 

Yes, it seems so from photos of the real thing and official GWR drawings.

 

Now to progress with the chassis.  The etched axle bearing 'holes' have been removed and the new sprung axle blocks and springs installed.  The block slots were opened up slightly with a triangular swiss file  to allow the slight side to side axle tilt required.  The etched dummy springs were bent aside to allow the axle blocks to be slid into place.  Prior to all this the etched axle location was marked on the sideframes to ensure that the sprung blocks covered the right range.  Height measurement of the footplate and smoke box when sitting on three wheels as indicates that the smoke box centre is about right but the buffer beam a bit low.

[Mark]

16 hours ago, Jeff Smith said:

Yes, it seems so from photos of the real thing and official GWR drawings.

 

Now to progress with the chassis.  The etched axle bearing 'holes' have been removed and the new sprung axle blocks and springs installed.  The block slots were opened up slightly with a triangular swiss file  to allow the slight side to side axle tilt required.  The etched dummy springs were bent aside to allow the axle blocks to be slid into place.  Prior to all this the etched axle location was marked on the sideframes to ensure that the sprung blocks covered the right range.  Height measurement of the footplate and smoke box when sitting on three wheels as indicates that the smoke box centre is about right but the buffer beam a bit low.

Yes the drawing you have shown is an official GWR drawing but it is a weight diagram and these are notorious for their inaccuracies. The drawing I referred to in my post is the frame diagram published in Great Western Journal and also an official Great Western document and generally far more representative than weight diagrams which are really only intended for axle loadings.

 

Regards

 

Mark Humphrys

Edited August 4, 2019 by Mark

[Jeff Smith]

23 hours ago, Mark said:

Yes the drawing you have shown is an official GWR drawing but it is a weight diagram and these are notorious for their inaccuracies. The drawing I referred to in my post is the frame diagram published in Great Western Journal and also an official Great Western document and generally far more representative than weight diagrams which are really only intended for axle loadings.

 

Regards

 

Mark Humphrys

Mark, which issue number of GWJ?

[melmoth]

32 minutes ago, Jeff Smith said:

Mark, which issue number of GWJ?

 

No. 19 possibly

[Jeff Smith]

1 hour ago, melmoth said:

 

No. 19 possibly

Thanks

[Jeff Smith]

I am assembling the Comet GWR 2-6-0 etched chassis.  The chassis fret LF29 includes a set of laminated coupling rods.  The motion fret LM20 also includes laminated coupling rods.  However the two sets are different with the LF29 rods much finer with smaller bosses.  Just wondered which might be the more appropriate size?

[Miss Prism]

What crankpin bushes are you using on your wheels?

 

[Jeff Smith]

Gibson

[Jeff Smith]

Not the best of photos but here are the two Comet frets.  Motion at the top, chassis below.  The size difference is evident but looking at lots of photos of 43xx class locos I can't tell which would be more appropriate.

 

Or perhaps there were two different standards fitted?

 

[Miss Prism]

If your Gibson crankpin bushes are 1.5mm od, then you can use the more modern skinnier coupling rod etches.

 

[Jeff Smith]

Thanks, are these closer to scale?

[Miss Prism]

Yes.

 

[Jeff Smith]

Ok, have now checked the frame plan in GWJ #19, which very conveniently is reproduced at a scale of 1mm to 1" , the coupling rods are 6" wide .  This means the wider rods as supplied on the motion etch at 2mm wide are correct......interesting!

[Miss Prism]

Don't forget to allow for cusp filing.

 

[Jeff Smith]

Just an update.  The firebox has been disassembled adjusted and rebuilt to get the top approximately horizontal, photo distortion makes it look as though it slopes forward but it actually doesn't!  The footplate/chassis relationship has been established to centre the wheels in the splashers and the chassis attachment points completed.  The Comet cylinders and slide bars have been assembled and attached by nut and bolt to the chassis.  The pony truck has been assembled and a pivot bolt soldered to the chassis.  A washer will be soldered to the slot on the pony truck to finalise the location at the correct wheelbase.  The drastic modification to the second to rear chassis spacer is to accommodate one of the gears.  The connecting rods and coupling rods have been assembled and drilled to accommodate the Gibson crank pin sleeves.  The Comet brass crossheads have been filed to fit the slidebars.