7mm Buckjumper's Workbench - Latest: GCR D8 open wagons

Discussion in 'Area 51' started by Buckjumper, 5 July 2012.

  1. 28ten

    28ten Guv'nor

    It might be a long shot, but I have just replenished my stock of mylar to cut Grahams wheel mask, and it might be possible to laser a mask for GC so you could try spraying the letters. I have successfully done 5 inch gauge LMS, but I'm not sure of the practicalities in 7mm
     
  2. Buckjumper

    Buckjumper Flying Squad

    I'd like to give that a go. I'll see what I can sort out for you later today with regard to size and shape. Even if the paint creeps under the mask I could cut it back in the same way excess lining from a bow pen is cleaned up.
     
  3. 28ten

    28ten Guv'nor

    What I need is a clean outline of the letters. In theory it should allow some interesting weathering effects for faded lettering.
     
  4. Buckjumper

    Buckjumper Flying Squad

    OK will do. Can you remind me again the file formats you're happy to work from. Cheers.
     
  5. 28ten

    28ten Guv'nor

    A .dxf is best of all, both illustrator and corel will export to .dxf but I can work with jpg and png. You can scan a good photo and trace it with splines, which is what I did for Western plates.
    If you ever want anything engraved (like a pub window!) then a .bmp is best. A current and slightly loony idea is to combine both for a broken window pane ;)
     
  6. Buckjumper

    Buckjumper Flying Squad

    My wife uses Illustrator all the time on her Mac, so that's fine.

    Pub window...I hear you!:thumbs:
     
  7. Tony West

    Tony West Western Thunderer

    Adrian, is this of any use ???.
    Cheers Tony.
     

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  8. Dog Star

    Dog Star Western Thunderer

    Tony - how much of the wagon is shown on the original source?
     
  9. Buckjumper

    Buckjumper Flying Squad

    Thanks Tony, but that's looking upwards so the lettering has a slight distortion. I've got a photo which has been taken almost perfectly square on to the wagon side which is a better starting point.
     
  10. Buckjumper

    Buckjumper Flying Squad

    Erm...once?
     
  11. Tony West

    Tony West Western Thunderer

    Graham, that is the whole photo !!....that implies that you havent yet built the D8 wagon(s) that you purchased back in 2005 !!!!....just cant get the staff !!!.
    Cheers (!!) Tony.
     
  12. Buckjumper

    Buckjumper Flying Squad

    gc_irons.jpg

    With the axle guards fitted it was time to look at the compensation units. As Tony has pointed out, the WEP units are only one of various kinds on the market, but for commissions which would normally require a solid chassis I find the WEP units are unobtrusive and go together with a minimum of fuss; simply fold up, and using an engineer's square to keep everything as it should be, a couple of dabs of solder from a hot iron fixes everything in place.

    gc_inside_bearings.jpg

    The bearings fit in the etched holes without the latter needing to be opened out, so once the solder's flashed around the edges a quick clean to neutralise the flux and the rocking units can be assembled by opening the holes to 0.9mm and pushing the supplied brass wire through, securing it in place by bending the ends to 90 degrees.


    I rub the backs of the wheels on some 180 grit wet & dry in a circular motion to remove any casting pips and ensure the backs are flat and true, then give the tyre fronts, treads, backs and axles a rub over with a Garryflex block (grey - medium grade), finally degreasing the wheels and axles with cellulose thinners before chemically blackening them.

    There's often a lot of hand-wringing about this process, but it's really very simple. Chemically blackening really is a misnomer (or should be) because that's not what we should be trying to achieve. How many prototype wheel treads are black? Exactly. What we should be aiming for is to tone down the bright shiny chrome steel of the wheels as supplied to a scale sheen appropriate for our models. I've a bit of a thing against using unadulterated real things on our models without knocking their colour and sheen back a little; coal, brass, copper, steel...how often do we read that nothing looks more like real coal than coal on a model? In reality real coal sitting in a tender or wagon looks nothing like a scaled down version of itself and looks much better for a little waft over with a matt black/leather/gunmetal mix from the airbrush to control the sheen.

    But I digress...I dilute Birchwood Casey Super Blue with water in a container to make a 10% solution and have some clean water in another container ready on the side. I lay out some paper towel and drop the axles into the solution leaving each one in there for 20 seconds. Then transfer the 'blackened' axle to the clean water and leave that for 20 seconds before fishing it out and drying it thoroughly on the paper. I then repeat the process with the wheels.

    The combination of chemically and mechanically cleaning the steel, followed by brief immersion in a weak solution will darken the steel perfectly without flaking. If things are a little patchy, it's simply down to that area not being clean or grease-free, so repeat the process! I've recently seen concerns written about inserts theoretically plasticising in the solution, but in 17+ years of blackening wheels like this have encountered no such problems. Incidentally, loco wheels treads can be blacked as the process doesn't interfere with electrical pickup.

    gc_wheels.jpg

    I give the axles and wheels a quick once-over with a hair dryer then fit a brass mop into the mini drill and buff the wheels and axles until they shine with a scaled down sheen. Some people like to coat them with light oil to keep rust at bay, but I rarely bother as next indignity the tyre faces and wheel backs suffer is a blast with black etch primer.
     
  13. iploffy

    iploffy OC Blue Brigade

    Question are there 2 rocker units per wagon or is it 3 point suspension
     
  14. Buckjumper

    Buckjumper Flying Squad

    Just the one rocker unit per wagon.
     
  15. Dog Star

    Dog Star Western Thunderer

    To avoid uncertainty - the wheels in the photo... before blackening?
     
  16. Buckjumper

    Buckjumper Flying Squad

    I think you've mis-quoted me there :))

    Nope, after.

    The tread of a prototype tyre is polished bright like chrome from contact with the railhead, but to my eyes that amount of shine looks wrong on a model. Likewise, a fully blackened tread looks wrong to me because they weren't black.

    What's needed is a shine that indicates the wheel is in frequent use, but scaled back in the same way we might scale paint . Here's a comparison shot:

    compare_wheels_blackened.jpg
     
  17. Buckjumper

    Buckjumper Flying Squad

    Pro tem the wheels have been put back onto their axles (which have been masked off with Tamiya tape) to aid the painting. I don't want primer or paint on the axles at this stage as they've yet to be fitted to the inside bearings. The plastic spokes have been cleaned up with a Swan Morton blade, files and wet & dry paper, but of course the camera sees all and in the enlargement they look pretty rough. C'est la vie.

    I then give the fronts and backs of the wheels a squirt with a black etch primer from an aerosol. My current lot is from ebay and the coverage is excellent. I find that with this primer I no longer need to bother with a top coat so that's a bonus.

    The solvent in the etch primer flashes off quickly leaving a very smooth slightly egg-shell finish with a nice dense colour, and within a few minutes the primer is dry enough to handle so the masking tape is peeled off and a cotton bud moistened with cellulose thinners is run over the tyre treads to remove the overspray, followed by a dry bud to mop up the remains.

    gc_wheels_primed.jpg

    One benefit of chemical blackening of the tyre treads is that it limits - even inhibits - the natural rusting process of the steel to a negligible manner, but another is that it it etches into the surface of the metal which means that the axles will not need priming before weathering. In fact, the only reason I prime the wheel faces and backs is because these areas tend to get some rough treatment and enamel weathering would ping off fairly quickly - the etch primer is far more tenacious, so it's simply a belt & braces approach.
     
    Brian Wainwright likes this.
  18. Dog Star

    Dog Star Western Thunderer

    Adrian - a thought for the next occupant on the bench. If the CPL crank pin nuts are not too tasteful for something to be found on the east side of the country... how about making a pattern and arranging a casting? Might even be a best seller here given the number of members who profess to have leanings towards BR(E) and its precursors.

    Could even make the item as per the prototype and fit a steel stud to a tapped hole in the casting - hence no need for a die which cuts to the underside of the nut.

    regards, Graham
     
  19. Rob Pulham

    Rob Pulham Western Thunderer

    You would find a home for some here.:thumbs:
     
  20. Buckjumper

    Buckjumper Flying Squad

    Cor, now there's an assumption! I had something else planned for here, but had to interleave two posts from elsewhere to enable the above comments to make sense :rolleyes:

    Wiseguys ;) :))

    As I said at the beginning, this isn't going to be the same as over there (a) , or even over there (b). Now if that ain't cryptic...

    Unhappy about the look of the standard crankpin retainers supplied with the AGH wheels, I bought some CPL replacements which are of the GWR pattern.

    r24_agh_crankpins.jpg

    However, my 10BA die wouldn't cut the threat up to the top, which meant the nuts (although physically they are bolts) stood proud. Instead I chopped the heads off, glued them to the stainless steel retainers and the improvement is immense.

    Funny pall on the photo though - possibly a combination of artificial light, and close photography causing strain on the sensor?

    r24_cpl_crankpins_fitted.jpg


    To be honest, the GW pattern is pretty close to that used on the GE, and I've no problem using the CPL ones again. Can't see it being a best seller either with the dearth of AGH wheels, so definitely on the "can't be bovvered" list!

    CPL crankpin nuts for Slater's wheels are completely different, in that they are proper nuts, not bolts masquerading as nuts. I'll have to see how they look after being tapped 10BA as they're cast with a 12BA thread, but again, the pattern is pretty close to the GE style, so...